Customisation of PVD coatings for biomedical devices

Cus omisa ion o PVD coa ings o biomedical de ices
☆
Daniela San o
a,*
, Jos´
e D. Cas o
a
, Sand a C uz
a,b
, Isabel Ca alho
c,d
, Albano Ca alei o
a,b
,
Sand a Ca alho
a,b
a
CEMMPRE, Depa men o Mechanical Enginee ing, Uni e si y o Coimb a, 3030-788 Coimb a, Po ugal
b
IPN - LED&MAT - Ins i u o Ped o Nunes, Labo a ´
o io de Ensaios, Desgas e e Ma e iais, Rua Ped o Nunes, 3030-199 Coimb a, Po ugal
c
CEB, Cen e o Biological Enginee ing, LIBRO—Labo a ´
o io de In es igaç˜
ao em Bio ilmes Ros´
a io Oli ei a, Uni e si y o Minho, Campus o Gual a , 4710-057 B aga,
Po ugal
d
LABBELS–Associa e Labo a o y, B aga/Guima ˜
aes, Po ugal
ARTICLE INFO
Keywo ds:
PVD coa ings
Magne on spu e ing
Biocompa ibili y
Osseoin eg a ion
An imic obial ac i i y
ABSTRACT
In ecen yea s, physical apo deposi ion (PVD) has eme ged as a powe ul echnique o su ace modi ica ion,
o e ing a wide ange o possibili ies o imp o e he p ope ies o medical de ices. This e iew explo es he
undamen als and e sa ili y o PVD coa ings in biomedical applica ions, highligh ing hei po en ial o e o-
lu ionise he ield. Biocompa ibili y is c ucial in success ully in eg a ing medical de ices wi h he human body.
The p ecise modi ica ion o hin ilms o imp o e biocompa ibili y, educe ad e se eac ions, and p omo e be e
issue in eg a ion is discussed. Osseoin eg a ion, ano he c i ical ac o o he success o o hopaedic and den al
implan s, is also explo ed in he con ex o magne on spu e ing coa ings. The abili y o hese coa ings o p o ide
a bioac i e su ace ha p omo es bone cell adhesion and g ow h is analyzed, shedding ligh on he po en ial o
ailo -made coa ings in imp o ing implan success a es. In ec ions associa ed wi h medical de ices pose a sig-
ni ican challenge in heal hca e se ings. S a egies, such as he inco po a ion o an imic obial agen s and su ace
modi ica ions, a e discussed, highligh ing he po en ial o his was e-ze o echnique in e ec i ely add essing his
c i ical issue. O e all, he e sa ili y, coupled wi h he abili y o enhance co osion esis ance, mechanical
p ope ies, ibological pe o mance, biocompa ibili y, osseoin eg a ion, and an imic obial ac i i y, makes PVD
coa ings highly p omising o imp o ing he pe o mance and unc ionali y o medical de ices. Con inued
esea ch and de elopmen in his ield will undoub edly lead o u he ad ancemen s in PVD coa ings, e o-
lu ionising he biomedical indus y.
1. In oduc ion
In ecen yea s, medical de ices (MDs) ha e become inc easingly
c i ical in add essing he complex challenges aced by mode n heal h-
ca e sys ems. Wi h an aging global popula ion seeking o main ain ac i e
li es yles, he demand o ad anced medical echnologies, such as join
eplacemen s, s en s, and ca he e s, con inues o ise [1–3]. These de-
ices play a i al ole in enhancing pa ien ou comes; howe e , hei
de elopmen and u iliza ion p esen a hos o challenges. Among hese
a e he g owing p e alence o bac e ial esis ance, which educes he
e ec i eness o con en ional an ibio ics, and he need o ma e ials wi h
enhanced biocompa ibili y, ex ended bioac i i y li e imes, and obus
esis ance o in ec ions [4–6].
Implan able de ices used in o hopaedic, den al, and ca dio ascula
applica ions a e p edominan ly made om me als, polyme s, and ce-
amics, wi h me als such as i anium (Ti) alloys, s ainless s eel (SS),
cobal -ch ome (Co
–
C ) alloys, zi conium-niobium (Z
–
Nb) alloys, and
magnesium (Mg) alloys being he mos common [3,7]. These ma e ials
a e alued o hei du abili y, biocompa ibili y, and mechanical p op-
e ies, including high s eng h, low modulus o elas ici y, and excellen
wea esis ance [3,8,9]. Howe e , despi e hei widesp ead use, hese
ma e ials ace limi a ions ela ed o co osion, wea , and bio ilm o -
ma ion [10,11]. Fo example, co osion by-p oduc s can leach in o
su ounding issues, causing in lamma ion and sys emic oxici y [7,12],
while ibological wea and deb is can lead o ad e se complica ions,
including implan loosening, ch onic in lamma ion, and e en de ice
ailu e [13–15]. Ca dio ascula de ices ace addi ional challenges, such
as hemolysis, h ombus o ma ion, and excessi e ic ion, all o which
☆
This a icle is pa o a Special issue en i led: ‘2IESSE-24’ published in Su ace & Coa ings Technology.
* Co esponding au ho a : Uni e si y o Coimb a, Depa men o Mechanical Enginee ing, 3030-788 Coimb a, Po ugal
E-mail add ess: [email p o ec ed] (D. San o).
Con en s lis s a ailable a ScienceDi ec
Su ace & Coa ings Technology
jou nal homepage: www.else ie .com/loca e/su coa
h ps://doi.o g/10.1016/j.su coa .2025.132277
Recei ed 29 Janua y 2025; Recei ed in e ised o m 5 May 2025; Accep ed 14 May 2025
Su ace & Coa ings Technology 512 (2025) 132277
A ailable online 21 May 2025
0257-8972/© 2025 The Au ho s. Published by Else ie B.V. This is an open access a icle unde he CC BY license ( h p://c ea i ecommons.o g/licenses/by/4.0/ ).
comp omise de ice unc ionali y and longe i y [16,17].
Following he implan a ion o medical de ices, a o eign body
esponse (FBR) is igge ed as pa o he body's de ense mechanism.
While his esponse is na u al, i o en leads o ch onic in lamma ion,
posing a se ious isk o long- e m de ice success. Ch onic in lamma ion
in e e es wi h he in eg a ion o he de ice in o su ounding issues,
pa icula ly in o hopaedic implan s whe e osseoin e-
g a ion—mechanical and biological s abili y achie ed h ough bone
adhesion—is c i ical o unc ionali y. The na u e o he bioma e ials
used plays a key ole in in luencing FBR. Ma e ials ha exhibi cy o-
oxici y, o en due o he elease o oxic ions o deg ada ion p oduc s,
exace ba e he immune esponse, leading o issue damage and p o-
longed in lamma ion [18,19]. Con e sely biologically ine ma e ials
may also hinde osseoin eg a ion, as hey ail o p omo e cellula
adhesion, p oli e a ion, and di e en ia ion—essen ial s eps o e ec i e
in eg a ion wi h bone issue. This lack o bioac i i y leads o he o -
ma ion o ib ous issue a he in e ace, educing mechanical s abili y
and inc easing he likelihood o de ice loosening and ailu e [20,21].
Simila ly, heal hca e-associa ed in ec ions ep esen a signi ican chal-
lenge o in asi e de ices such as ca he e s, whe e bio ilm o ma ion on
ma e ial su aces is a common cause o in ec ion [4]. Con en ional so-
lu ions, such as he inco po a ion o an ibio ics, a e becoming less
e ec i e due o he eme gence o esis an bac e ial s ains, necessi-
a ing he de elopmen o al e na i e s a egies [4–6]. Fu he mo e,
single-use MDs, while e ec i e in educing c oss-con amina ion and
in ec ion isks, pose ano he dilemma: hei en i onmen al impac
[22,23]. Classi ied as in ec ious was e, hese de ices o en equi e
incine a ion, con ibu ing o g eenhouse gas emissions and pollu ion
[22]. This ension be ween public heal h bene i s and en i onmen al
sus ainabili y unde sco es he u gency o de eloping eco- iendly
al e na i es.
To add ess hese mul i ace ed challenges, ad ancemen s in ma e ials
science and su ace enginee ing ha e eme ged as key solu ions. Ma e ial
modi ica ions, such as me al injec ion molding [24] and addi i e
manu ac u ing [25,26], combined wi h inno a i e bioma e ials like
collagen [27] and hyalu onic acid [28], a e ans o ming he landscape
o MDs. Addi ionally, su ace enginee ing echniques, including plasma
sp aying, elec opla ing, physical apo deposi ion (PVD) [8], and lase
ea men s, o e signi ican imp o emen s in co osion esis ance,
biocompa ibili y, bioac i i y, and an imic obial p ope ies [8,29–32].
Among hese, PVD—pa icula ly magne on spu e ing—has demon-
s a ed excep ional po en ial in ailo ing ma e ial su aces o be e
mimic biological sys ems, ex end de ice li espan, and enhance clinical
ou comes (Fig. 1) [32,33].
This e iew ocuses on coa ings p oduced by magne on spu e ing,
emphasizing ad ancemen s achie ed o e he pas i e yea s in he ield
o biomedical de ices. To he bes o ou knowledge, his is he i s ime
a de ailed analysis has been conduc ed on how his echnique can be
ailo ed o op imize c ucial ilm cha ac e is ics—such as composi ion,
hickness, adhesion, mo phology, and c ys alline s uc u e enabling he
ine- uning o physical, chemical, mechanical, and biological p ope ies
o hin ilms o mee speci ic medical applica ion equi emen s. The
discussion explo es how PVD enhances key su ace p ope ies o medical
de ices. I add esses imp o emen s in co osion esis ance o p e en
ma e ial deg ada ion in physiological en i onmen s, upg ades o me-
chanical p ope ies and ibological pe o mance o enhanced du a-
bili y, and modi ica ions o biocompa ibili y o imp o ed issue
in eg a ion. Addi ionally, i e alua es PVD's ole in os e ing osseoin e-
g a ion o o hopaedic applica ions and boos ing an imic obial ac i i y
o comba bio ilm o ma ion and heal hca e-associa ed in ec ions. The
main limi a ions o commonly used subs a e ma e ials a e add essed,
alongside an analysis o he mos e ec i e coa ings designed o o e -
come hese challenges. This comp ehensi e app oach p o ides a
de ailed unde s anding o how magne on spu e ing no only add esses
he limi a ions o adi ional ma e ials bu also enhances he pe o -
mance, eliabili y, and du abili y o medical de ices, pa ing he way o
nex -gene a ion biomedical applica ions.
2. Why PVD as su ace enginee ing me hod o biomedical
applica ions?
Su ace enginee ing s a egies o e p omising solu ions o enhance
he unc ionali ies o biomedical de ices. These s a egies in ol e
a ious deposi ion echniques, which can be b oadly classi ied in o
Fig. 1. O e iew o medical de ices and ma e ials challenges, emphasizing he need o enhanced pe o mance h ough ailo ed coa ings. PVD highligh ed as a
p ecise and eco- iendly me hod o imp o e mechanical and biological p ope ies o medical de ices. C ea ed in h ps://BioRende .com.
D. San o e al.
Su ace & Coa ings Technology 512 (2025) 132277
2
hose in ol ing chemical eac ions, such as elec ochemical deposi ion,
sol-gel echniques, and chemical apo deposi ion, and hose in ol ing
physics concep s such as cas ing, sp aying, and PVD [8]. Among hese
echniques, PVD s ands ou wi h i s unique ad an ages, pa icula ly in
he ield o biomedical de ices. This echnique in ol es physical p o-
cesses, educing chemical was e, and minimizing en i onmen al impac .
I o e s excep ional e sa ili y, enabling he deposi ion o almos any
ma e ial on o biomedical de ices. One o he key s eng hs o PVD lies
on i s abili y o achie e p ecise con ol o e su ace p ope ies a he
a omic le el, encompassing ac o s such as ilm hickness and chemical
composi ion. The e o e, coa ings wi h hicknesses ha can a y om a
ew nanome e s o se e al housand nanome e s, wi h he mos di e se
chemical composi ion, can be deposi ed [34]. Addi ionally, PVD ensu es
excellen adhesion, p omo ing long- e m s abili y and pe o mance o
biomedical de ices. The echnique also enables he deposi ion o ho-
mogeneous laye s wi h high pu i y, designed s uc u es, g aded p op-
e ies, and con olled mo phology. This le el o con ol o e ilm
p ope ies is highly ad an ageous o biomedical applica ions, whe e
speci ic unc ionali ies and pe o mance cha ac e is ics a e desi ed [35].
Howe e , i is impo an o acknowledge ce ain limi a ions o PVD
[36]. Coa ing la ge o complex-shaped objec s can pose challenges due
o limi a ions in he size o he acuum chambe o he uni o mi y o he
coa ing ac oss he en i e su ace. The line-o -sigh na u e o PVD depo-
si ion can lead o une en o incomple e co e age on in ica e su aces.
Addi ionally, PVD sys ems can be cos ly o acqui e and main ain. To
mi iga e hese limi a ions, esea che s ha e implemen ed mul iple
s a egies. Fo example, ine- uning deposi ion pa ame e s helps
imp o e coa ing uni o mi y, while subs a e manipula ion echniques
like o a ion, il ing, o in oducing a biased subs a e holde can
enhance coa ing uni o mi y on complex su aces. The de eloping o new
echnologies also has con ibu ed o o e come his si ua ion. High-
powe impulse powe sou ces ha e been employed in magne on spu -
e ing o achie e a uni o m coa ing in complex su aces [37]. In addi-
ion, ad anced chambe designs ha e been de eloped o o e come he
line-o -sigh deposi ion limi a ion, allowing o mo e uni o m
co e age. Finally, combining PVD wi h o he deposi ion echniques
p o ides addi ional con ol and lexibili y in he deposi ion p ocess
[38,39]. By conside ing hese limi a ions and employing app op ia e
s a egies, esea che s can op imize PVD o biomedical applica ions
and unlock i s ull po en ial in enhancing he pe o mance and unc-
ionali y o medical de ices.
PVD is based on he deposi ion o hin ilms ia ei he e apo a ion o
spu e ing o a ge ma e ials in a high- acuum en i onmen , ensu ing
ilm pu i y and p ecise con ol o e composi ion [40]. While e apo a-
ion equi es high empe a u es and is hus limi ed in coa ing hea -
sensi i e subs a es, spu e ing—pa icula ly magne on spu e ing
(MS)—can be pe o med a lowe empe a u es, making i sui able o
applica ions such as medical de ices. Common spu e ing echniques
include DC, RF, eac i e spu e ing, and HiPIMS, each o e ing speci ic
ad an ages in ailo ing ilm p ope ies such as densi y, composi ion, and
mechanical s eng h o mee di e se pe o mance equi emen s [41].
2.1. Magne on spu e ing: a PVD p ocess o ine- uning hin ilm
p ope ies
In he con ex o medical de ices, achie ing p ecise con ol o e he
coa ing cha ac e is ics deposi ed by magne on spu e ing is c ucial.
This enables he cus omiza ion o coa ings o mee speci ic e-
qui emen s, such as co osion and wea esis ance, low ic ion,
biocompa ibili y, and an imic obial ac i i y, he eby enhancing hei
pe o mance in medical applica ions. The e a e se e al e ec i e ap-
p oaches o ine- uning he chemical composi ion o coa ings deposi ed
by MS. The p ima y de e minan o he coa ing's chemical composi ion
is he choice o a ge ma e ial. By selec ing a ge ma e ials wi h
a ying elemen al composi ions o combining, di e en elemen al
a ge ma e ials, coa ings wi h complex chemical composi ions can be
achie ed [42]. Mo eo e , he addi ion o alloying elemen s o dopan s
can u he add new p ope ies o he ilm. Fo ins ance, by inco po-
a ing sil e (Ag) [2,43–46], coppe oxide (CuO, Cu
2
O) [47], o zinc
oxide (ZnO) [48–50] in o a base-coa ing ma ix, an imic obial p ope -
ies can be acqui ed. Simila ly, he inco po a ion o an alum (Ta) can
enhance he osseoin eg a ion o den al implan s [51–54] and imp o e
he subs a e's esis ance o wea and co osion [55,56]. Ano he
app oach is o use mul iple a ge s simul aneously o sequen ially [57].
This echnique allows o he c ea ion o mul i-laye ed coa ings o he
inco po a ion o speci ic elemen s o compounds in o he ilm s uc u e,
he eby enhancing hei e ec i eness in a ious applica ions [58–60].
Fo ins ance, i anium-coppe (TiCu) coa ings we e ob ained employing
a co-spu e ing sys em, deposi ing a he same ime he men ioned ele-
men s. The ob ained coa ings ha e been p o en o signi ican ly enhance
he co osion esis ance o s ainless s eel subs a es wi h he Ti inco -
po a ion [61]. In ano he example, he sequen ial deposi ion o silicon/
diamond-like ca bon (Si/DLC) nanolaye s has demons a ed i s abili y o
imp o e he biocompa ibili y o he coa ing [62]. Fu he mo e, he use
o sil e /mon mo illoni e biocomposi e mul ilaye s showed p omise in
p o iding e ec i e an i ungal ac i i y [63]. In addi ion o combining
a ge ma e ials, he in oduc ion o eac i e gases du ing spu e ing is
ano he e ec i e me hod o al e ing he chemical composi ion o
deposi ed ilms. Fo ins ance, by spu e ing a i anium a ge wi h sil e
pins in an A /O
2
/N
2
a mosphe e, TiO
2
:Ag,N coa ings we e p oduced,
o e ing unique p ope ies and unc ionali ies [64]. In ano he example,
Z
–
C coa ings we e deposi ed on 304 L s eel using a zi conium (Z )
a ge in an A -C
2
H
2
a mosphe e [65] o enhance he ha dness and wea
esis ance o he s eel subs a e. Fu he mo e, a i anium-coppe oxide
(TiCuO) coa ing was deposi ed on Ti6Al4V discs, esul ing in an
enhanced an imic obial ac i i y [66]. By adjus ing he low a es o
eac i e gases in PVD, he ex en o chemical eac ion wi h he spu e ed
a oms can be con olled, enabling he cus omiza ion o he composi ion
o he deposi ed ilm [65,66]. Fo example, he manipula ion o he on-
o low sequence o spu e ing gas allows o con ol o e he oxygen
con en and mo phology o ZnO hin ilms [67]. The use o eac i e gas-
iming du ing deposi ion leads o he o ma ion o g ainy nanopo ous
s uc u es in he hin ilms. On he o he hand, he deposi ion p ocess
con ibu ed o he inc ease o Zn
–
O bonding p esence in he coa ings,
which is c i ical o de elop he eac i e oxygen species (ROS) an ibac-
e ial mechanism. A mixed ac ion o mo phology and ROS induced a
highe an i ungal ac i i y in he ZnO coa ings han uncoa ed Ti. Mo e-
o e , he ine- uning o he chemical composi ion can be achie ed by
adjus ing a ious p ocess pa ame e s, namely spu e ing powe , gas
p essu e and deposi ion. Fo ins ance, when a nano-laye o gallium
oxide (Ga
2
O
3
) was deposi ed on o i anium dioxide nano ube a ays
using a 50 W powe , i exhibi ed lowe le els o Ga
3+
ions elease
compa ed o he same coa ing p oduced a 100 W. This can be explained
by he mo phological change in he samples. As he powe inc eased, he
nano ube a ays we e mo e co e ed by he coa ing, which makes mo e
ma e ial a ailable o eac wi h he su ounding media and hence,
elease mo e Ga
3+
ions [68]. This esul ed in coa ings ha demons a ed
an ibac e ial and os eogenic p ope ies wi hou inducing cy o oxici y,
making hem highly p omising o den al implan applica ions. By
me iculously conside ing and ine- uning hese ac o s, magne on
spu e ing o e s a highly e sa ile pla o m ha allows o p ecise
con ol o e he chemical composi ion o coa ings.
The mo phology o hin ilms is ano he c i ical ac o ha signi i-
can ly impac s hei chemical, physical, mechanical, and biological
p ope ies. By adjus ing magne on spu e ing condi ions, i is possible
o ailo he mo phology o hese ilms o mee speci ic equi emen s.
Highe spu e ing powe , o example, can lead o inc eased kine ic
ene gy upon deposi ion, causing su ace di usion and ea angemen o
a oms, esul ing in a smoo he and dense ilm mo phology. Fo
ins ance, El-Hossa y and co-wo ke s employed DC pulsed magne on
spu e ing o deposi a Ti-Al-N hin ilm on AISI 316, a ying he pulsed
plasma powe s be ween 100 and 175 W [69]. Among he di e en
D. San o e al.
Su ace & Coa ings Technology 512 (2025) 132277
3
powe se ings, he Ti-Al-N hin ilm deposi ed a a pulsed powe o 150
W exhibi ed he highes cell p oli e a ion a e. This posi i e e ec was
a ibu ed o a highe su ace ene gy and educed su ace oughness o
he ilm. The bias applied du ing MS deposi ion can also ha e signi ican
e ec s on he mo phology o he deposi ed hin ilms. In a s udy con-
duc ed by Bai e al., he impac o ion bomba dmen , by applying a
ange o nega i e bias ol ages om 0 o 100 V o he subs a e, on he
g ow h o TiO
2
ilms was in es iga ed [70]. The bomba dmen esul ed
in enhanced nuclea ion, leading o smalle g ain size and highe packing
densi y o he TiO
2
ilms. Mo eo e , he inc ease in bias ol age also had
posi i e e ec s on se e al mechanical and chemical p ope ies,
including ha dness and wea and co osion esis ances [62,70]. The
mo phology o hin ilms has a p o ound impac on cell adhesion, p o-
li e a ion, and di e en ia ion [71]. Su ace oughness and opog aphical
ea u es a e pa icula ly in luen ial p omo ing cell a achmen and
educing bac e ia adhesion. In a s udy conduc ed by Wang e al. in es-
iga ed he e ec s o oxygen con en on he s uc u e, composi ion,
su ace oughness, and we abili y o TiO
2
-CuO composi e spu e ed
coa ings [72]. As he oxygen con en inc eased, he coa ing composi ion
shi ed om TiO
2
-Cu o TiO
2
-Cu
2
O and TiO
2
-CuO
2
. Among he h ee
coa ings, he one con aining Cu
2
O exhibi ed he bes mul i unc ional
pe o mance, displaying he highes an ibac e ial a e, cy ocompa i-
bili y, and co osion esis ance. This ou s anding pe o mance can be
a ibu ed o he highe su ace oughness and good su ace we abili y.
These cha ac e is ics (i) acili a e he imp o ed con ac wi h cell g ow h
medium, (ii) p omo e he elease o Cu ions, and consequen ly (iii)
enhance he coa ings' an ibac e ial p ope ies and biocompa ibili y.
Simila ly, Ja id e al. conduc ed a s udy whe e hey a ied he wo king
p essu e and powe densi y o a Cu a ge [73]. This manipula ion
allowed con ol o e he mo phology o he hin ilms as well as he
amoun o Cu ions eleased, pe mi ing o op imize he an ibac e ial
ac i i y.
The c ys alline s uc u e o hin ilms also plays a signi ican ole on
hei p ope ies. The p esence o some c ys al phases can in luence o e
he ilm's ha dness, Young's modulus, and s eng h [74–76]. Mo eo e ,
he c ys alline s uc u e a ec s he su ace oughness and opog aphical
ea u es o hin ilms and can impac biocompa ibili y and in e ac ions
wi h biological sys ems, in luencing cell adhesion, p oli e a ion, and
di e en ia ion. Ruan e al. deposi ed i e di e en i ania ilms
(including one u ile, wo ana ase, and wo amo phous i ania), wi h
a ying le els o oughness, on polished i anium using RFMS [76]. The
esul s demons a ed ha he p esence o he ana ase phase wi h an
inc eased oughness e ec i ely enhanced he biocompa ibili y o he
coa ings. By manipula ing he magne on spu e ing pa ame e s, e-
sea che s can op imize he mic os uc u es and c ys alline a angemen s
in hin ilms. Fo ins ance, o in es iga e he po en ial di e ences in
pho oca aly ic and an ibac e ial ac i i ies associa ed wi h di e en
c ys alline phases o TiO
2
, Pa a on o e al. deposi ed ana ase, u ile, and
mix u e phases ilms on o comme cially pu e i anium (cpTi) [74,75].
The u ile-TiO
2
ilm had no an ibac e ial e ec , whe eas bo h ana ase
and mix u e-TiO
2
ilms demons a ed s a is ically signi ican educ ions
in bio ilm o ma ion.
O e all, by ca e ully conside ing and op imizing all he ac o s
men ioned, MS p o ides a e sa ile pla o m ha allows o p ecise
con ol o e coa ing p ope ies. This le el o con ol enables he c ea ion
o ailo ed coa ings wi h speci ic cha ac e is ics, g ea ly enhancing
c ucial aspec s such as co osion esis ance, biocompa ibili y, osseoin-
eg a ion, o an imic obial ac i i y o medical de ices.
3. How can PVD enhance he su ace p ope ies o medical
de ices?
The human body is a e y complex and dynamic en i onmen o
ino ganic ma e ials exposed o i . O e he yea s, many ials ha e been
documen ed o c ea e a solid da abase o biocompa ible ma e ials
ailo ed o speci ic body pa s and hei espec i e unc ions. Cu en ly,
a wide ange o medical de ices, such as ee h, hips, and suppo ing
sc ews, a e eadily a ailable o use by medical p o essionals, and he
esea ch eams a e ying o expand he op ions. Alloys such as Ti-6Al-4
V, AZ-se ies Mg o SS316L a e conside ed biocompa ible wi h he
human body [77,78]. Howe e , he used alloys can elease oxic ions
du ing hei in e ac ion wi h he biological en i onmen s, p esen ing
c ucial unc ional p oblems such as osseoin eg a ion inhibi ion [79–81]
o poo co osion esis ance [82–84].
Coa ings ha e been sui able o enla ging subs a e unc ionali ies in
se e al ields, and biomedical de ices a e no excep ion. O e passing he
men ioned d awbacks and addi ional bene i s can be add essed when
he su ace ea men is ailo ed o b ing he bes ea men o he human
body while a oiding possible complica ions. Coa ings applied by PVD
ha e been ab oad since supplying a s able and eliable pe o mance in
any subs a e. Co osion esis ance, mechanical p ope ies, ibological
pe o mance, and biocompa ibili y a e some p ope ies ha can be
imp o ed in biomedical de ices h ough PVD coa ings. Examples o
coa ings de eloped by ou esea ch g oup a e shown in Fig. 2. In he
ollowing sec ions, we a emp o summa ise how PVD coa ings ha e
been applied o inc ease he base pe o mance o di e en biocompa -
ible subs a es and enla ge hei wo king bene i s.
3.1. Imp o ing co osion esis ance in MDs
One o he signi ican issues o applying me allic implan s in o he
human body is he g ade o deg ada ion p esen ed wi h he exposu e
ime, c ea ing addi ional heal h p oblems o he pa ien s, as men ioned.
Co osion is a qui e s udied phenomenon ha is ans e sal o all in-
dus ies. Speci ic ma e ials a e commonly employed acco ding o he
wo king egime o speci ic solu ions/en i onmen s hey mus deal wi h.
Fo ins ance, s ainless s eel is a e sa ile ma e ial used o igh agains
his issue. Some me als can eac wi h hei su oundings, o ming an
addi ional laye o e hemsel es, like a sel -p o ec i e mechanism,
which s ops he ex e nal agen 's ac ion. This con o med laye is
commonly known as he passi e laye . Howe e , he men ioned laye
can also be a ec ed by ex e nal agen s (agg essi e solu ions) and ac ions
(wea , e osion), which cause a co osion e en o happen.
In MDs, exis wo common co osion mechanisms epo ed in PVD
coa ings: (1) Pi ing, which is he o ma ion o pi s p o oked by speci ic
b eakdowns in a passi e su ace; (2) gal anic, which happens due o he
dissimila i y o he me als in con ac unde he p esence o an elec o-
ly e, and co oding he mo e ac i e ma e ial. Expe imen al es s such as
po en iodynamic pola isa ion a e sui able o p o oking co osion
e en s in an accele a ed way, and mic og aphic es s help o es ablish
he ype o co osion p esen ed. Fig. 3a exhibi s he ypical po en io-
dynamic pola isa ion plo , commonly named he Ta el plo . I con ains
se e al egions desc ibing phenomena p oduced by he po en ial inpu
in he sample. F om nega i e o posi i e po en ials, he plo is di ided
in o a ious a eas: ca hodic eac ion, anodic eac ion, and passi e e-
gion. Addi ional phenomena in his kind o plo a e desc ibed elsewhe e.
The b eakdown o he passi e laye is a clea sign o co osion ac ion.
The sudden cu en densi y inc eases and quickly dec eases (see he
egion named “B eakdown o passi e laye ” in Fig. 2, is he s anda d
signal when pi ing happens du ing he pola isa ion es . Mic og aphy
assesses and shows he co osion ac ion on he specimens (example
shown in Fig. 3b). In he ollowing sec ions, we explo e how common
MD subs a es we e coa ed by o he ma e ials ia PVD echnologies,
such as alloys (based in Ti o Mg), s ainless s eel o o he biocompa ible
ma e ials (polyme s), and hei impac on imp o ing co osion p o ec-
ion o e biological en i onmen s, mainly ocused on he human body
condi ions.
3.1.1. S ainless s eels
Despi e s ainless s eel being one o he mos used alloys o MDs
[90,91], eleasing o oxic ions in o he bloods eam, such as Ni
2+
and
C
3+
, is a big issue o o e come. Besides co osion, which p o okes he
D. San o e al.
Su ace & Coa ings Technology 512 (2025) 132277
4
educ ion o MD li espan and unc ionali y jeopa dizes, he e is he
po en ial o cause p oblems such as bone e osion o asep ic loosening o
he implan , which can ha e signi ican consequences on he pa ien 's
well-being and he success o he implan [91]. This si ua ion compels
he esea ch eams o achie e su aces wi h highe co osion esis ance
in ha sh biological en i onmen s. Di e en ypes o mix be ween
me allic and ce amics ha e been used o coa his ma e ial and ha e
been es ed, as shown in he ollowing able.
S ainless s eel is well-known as a ma e ial wi h sel -healing p ope -
ies when exposed o oxidising agen s as human body luids (Fig. 4). I is
capable o o m a passi e laye composed by C
2
O
3
o co e i sel and
s op co osion. Howe e , he passi e laye is mechanically poo , hence i
could be emo ed by ex e nal ac ion easily, and consequen ly, c ea es
some unp o ec ed zones. He e, coa ings a e c i ical o ein o ce he
Fig. 2. Schema ic o e iew o he main unc ional applica ions o PVD coa ings o medical de ices, illus a ed by SEM mic og aphs and schema ic diag ams.
Co osion- esis an Z N coa ings ea u e dense, de ec - ee s uc u es ha enhance p o ec ion in physiological en i onmen s [85]. a-C and a-C/Ag coa ings imp o e
mechanical pe o mance h ough nanos uc u ed, columna g ow h [86]. TaCaP-Zn coa ings p omo e biocompa ibili y by o e ing a a o able su ace o cell
adhesion [39]. CaP-AgO coa ings suppo osseoin eg a ion h ough nano- ough, po ous su aces ha encou age bone a achmen [87]. TiN-Ag and TaCaP-Zn2C
coa ings enhance an imic obial ac i i y ia sil e and zinc nanopa icle inco po a ion [49,88].
Fig. 3. Schema o a po en iodynamic pola isa ion plo (a) and SEM mic og aph o SS316L coupon a e pola isa ion es (b), which e idences he pi ing co osion.
Image (b) was adap ed om [89].
D. San o e al.
Su ace & Coa ings Technology 512 (2025) 132277
5

an ico osion ac ion in ha sh en i onmen s such as human body. Table 1
exposes he main s a egy in PVD coa ings o MDs, which is employing
passi e ma e ials such as C o Z O
2
, commonly used o inhibi co osion
o o he pu poses due o hei high chemical s abili y in se e e wo king
condi ions. Acco ding o he summa ised e e ences in Table 1, passi -
a ion was he mos common p o ec ion mechanism agains co osion
unde simula ed biological condi ions. I s a s wi h ionising he su ace
me al a oms, which in e ac wi h he solu ion, ini ialising he elec o-
chemical eac ions wi h he elease o elec ons. La e , he me al ions
eac wi h he solu ion (commonly O and OH ions) o con o m oxides
and hyd oxides ha con igu e an ou e mos laye , which can ac as a
p o ec i e ba ie .
On he o he hand, o he coa ings in Table 1 shown pi ing, which is
explained o o he possible easons causing his beha io ( o ins ance,
su pe icial de ec s o he e ogeneous chemical species) and no he
in e ac ion o he applied coa ing wi h he bio-liquid i sel . Kao e al.
[92] desc ibed ha he de ec s (pinholes) ound in TiN ilm ac ed as a
s a ing poin o co osion, and Cubillos e al. [91] he impe ec ions in
he ‘as-deposi ed’ condi ion ilm mo phology. Besides, Qin e al. [61]
jus i y he educ ion o pi s a e annealing he dense TiCu coa ings by
he une en elemen al dis ibu ion along he ilm su ace. This could be
ano he c i ical cha ac e is ic o explain he pi ing p ocess in compac
su aces. F ee-de ec su aces wi h a uni o m passi e coa ing could
p e en co osion in coa ed s ainless s eel MDs.
In spi e o he capaci y o s ainless s eel o sel -heal is ou s anding,
s opping he ac ion o he ex e nal agen s can comp ise i s in eg i y and
p o ec ion pe o mance. Especially, solu ions ha simula e body luids,
such as SBF and PBS, con ain o he ions, such as Na
+
, K
+
, Ca
2+
, Mg
2+
o
Cl
-
, being highly agg essi e o s ainless s eel MDs. PVD coa ings ha e
demons a ed o be e ec i e o enhance he p o ec ion o his ma e ial in
biological en i onmen s, hence hei applica ion can be a sui able op-
ion o o e come co osion in MDs.
3.1.2. Ti-based alloys
Ti anium is p obably he mos used biocompa ible ma e ial in human
body implan s because o i s high oughness, easy machinabili y, and
high co osion esis ance [77]. Simila ly o s ainless s eel, Ti-based al-
loys o en p esen a mechanically poo TiO
2
laye due o i s sel -healing/
Fig. 4. Schema o a passi e laye o s ainless s eel exposed o he ai .
Table 1
Co osion/p o ec ion mechanisms o coa ings used o unc ionalise s ainless s eels o biomedical de ices.
Subs a e/ ilm Applied echnologies Co osion
es s
Elec oly e P o ec ion/co osion
mechanism
Po en ial applica ion Re .
SS316L/TiN DCMS PP 0.9 w % NaCl
solu ion
Pi ing O hopaedic, ca dio ascula and
den al de ices
[92]
SS304/calcium phospha e and
calcium i ana e
RFMS PP Hank's solu ion (@
37 ◦C)
Passi e laye Femo al s em implan s [93]
SS420/TiAlN(Ag,Cu) DCMS EIS
b
& PP 1 w % NaCl
solu ion
Passi e laye Su gical and den al
ins umen a ion
[90]
SS316L/(Ag, Ag-Au)a:C DCMS EIS & PP A i icial u ine (@
37 ◦C)
Passi e laye U e e al s en s [94]
SS316L/TiCu DCMS & HiPIMS +annealing
(up o 500 ◦C)
PP PBS Pi ing No in o med [61]
SS304L/Z C Pulsed-DCMS PP A i icial sali a Passi e laye O hodon ic wi es [65]
SS316L and SS304/Z O
x
N
y
DCMS EIS & PP 3.5 w % NaCl
solu ion
Pi ing Implan s [91]
SS316L/H C RFMS EIS & PP PBS (@ 37 ◦C) No in o med Ca dio ascula implan s [95]
SS316L/C
2
O
3
RFMS PP 0.9 w % NaCl
solu ion
Passi e laye O hopaedic implan s [96]
SS316L/Nb
2
O
5
-TiO
2
RFMS EIS & PP Ringe 's solu ion Passi e laye O hopaedic implan s (join s) [97]
SS316L/Z O
2
DCMS EIS & PP Hank's solu ion (@
37 ◦C)
Passi e laye O hopaedic implan s (join s) [98]
SS316L/a:C DCMS Imme sion A i icial sali a (@
37 ◦C)
Passi e laye O hodon ic implan s [99]
a
Po en iodynamic pola isa ion.
b
Elec ochemical impedance spec oscopy.
D. San o e al.
Su ace & Coa ings Technology 512 (2025) 132277
6
p o ec ion mechanism when is exposed o oxidising agen s [80,81]. In
ecen yea s, comme cial pu e Ti (cp-Ti) o indus ial-g ade pu e Ti
(TA2) ha e gained a en ion due o hei lowe p ice han o he Ti alloys
( o ins ance, Ti-6Al-4 V) and o he bioma e ials.
Acco ding o Table 2, he coa ings employed o a oid co osion in Ti-
based alloys ha e also been employed o enla ge he unc ionali y o he
MDs u he o p e en he elease o hea y me allic ions in o he body.
A la ge a ie y o ma e ials ha e been employed o coa Ti-based alloys
used in MDs: Pd/PdO [77], Z [100,101], Zn [101], C (i.e., diamond-like
ca bon o DLC) [157], Ag [102], hyd oxyapa i e (HAp) [103], Ta [55],
and Cu [104]. He e, magne on spu e ing e sa ili y is e iden o coa
MDs acco ding o he aimed p ope y o enhance. Ne e heless, some
coa ings shown in Table 2 ha e been ea ed a e deposi ion o ac i a e
some desi ed cha ac e is ics. Fo ins ance, Ra iee ad e al. deposi ed Pd
o e Ti-6Al-4 V subs a es h ough DCMS in an ine a mosphe e o
achie e app oxima ely 2.3
μ
m hickness ilms and a e wa ds, he
samples we e he mically ea ed employing di e en empe a u es
(450, 550 and 650 ◦C) o 1 h unde no mal a mosphe ic condi ions
[77]. This p ocessing was de e mined o p o oke he di usion om he
ilm o he subs a e, which con ibu es o ein o cing he subs a e/
coa ing adhesion and enhancing he coa ed alloy's co osion esis ance
and mechanical p ope ies. Wang e al. [101] used RF magne on
spu e ing wi h mic o-a c oxida ion o ob ain Zn-doped ilms o Z O
2
o e comme cially Ti-6Al-4 V disks, ob aining an an ibac e ial e ec
h ough his coa ing ea men , which is c i ical in a oiding implan i is
o ela ed diseases. Chen e al. [105] deposi ed an I laye o e cp-Ti,
and a e ha , his laye was ac i a ed in an elec ochemical way o
c ea e I O
x
species, inc easing i s co osion esis ance wi hou p o okes
cy o oxici y. He e al. [106] ob ained TiCu coa ing o e TA2 subs a es,
and la e , he samples we e annealed a 600 ◦C o 2 h o ge a TiO
2
/CuO
con igu a ion, showing an enhanced biocompa ibili y, high co osion
esis ance and an ibac e ial ac i i y. Thanga el e al. [102] deposi ed
NiTi wi h Ag o achie e good co osion esis ance and cy ocompa ibili y
su aces o e cp-Ti subs a es. Milan e al.[107] coa ed Ti-6Al-4 V cou-
pons using magne on spu e ing in a eac i e a mosphe e o a gon and
me hane, ob aining Cu/a-C:H (amo phous ca bon) ilms wi h enla ged
unc ionali es in e ms o an ibac e ial p ope ies, angiogenesis, and
os eogenesis. These enhancemen s a e undamen al o he long- e m
s abili y and success o he implan . These s udies showcase he po en-
ial o PVD coa ings o c ea e su aces wi h mul i unc ionali y and
enhanced p ope ies di ec ed o expanding he ange o op ions o MDs.
The coa ings employed o imp o e he co osion esis ance in Ti-
based alloys shown passi a ion as he mos common p o ec ion mech-
anism agains simula ed body luids acco ding o Table 2, which is ex-
pec ed when passi e ma e ials a e used. As men ioned in he las sec ion,
his phenomenon also wo ks as a sel -p o ec i e laye agains haza dous
agen s. Besides pi ing co osion, gal anic co osion also appea and
seem ac s o e wo speci ic coa ings: Si:N-DLC [157] and Cu-a-C:H
[107]. As explained, gal anic co osion appea s when dissimila ma e-
ials a e in con ac in o an elec oly e. Those wo coa ings con ain ca -
bon as cons i uen . Speci ically, g aphi e, a e y common phase in DLC
and a-C:H coa ings, is one o he mos noble ma e ial acco ding o he
gal anic se ies [108]. Hence, mos o he me als in con ac wi h his
ma e ial is p one o be co oded. Acco ding o Zhang [108], when he
gal anic co osion occu s, he anodic (o mo e ac i e) membe is
eleased in o de o p o ec he ca hodic (o mo e noble) one. This
pa icula dissolu ion could gene a e in eg i y p oblems in MDs as ex-
hibi s Fig. 5, educing d as ically in unc ionali y and li espan. To a oid
his co osion ype, a e commonly ecommended since a oid dissimila
conduc i e ma e ials con ac s, isola ion o he coupled ma e ials om
Table 2
Co osion/p o ec ion mechanisms o coa ings used o unc ionalise Ti-based ma e ials o biomedical de ices.
Subs a e/ ilm Applied echnologies Co osion es s Elec oly e P o ec ion/co osion mechanism Po en ial applica ion Re .
TA2/TiO
2
-CuO Pulsed-DCMS +annealing
(up o 600 ◦C)
EIS
a
& PP
b
(@
36.5 ◦C)
SBF
c
Passi e laye Implan s [106]
TA2/Si:N-DLC Hyb id ion beam sys em PP SBF Gal anic O hopaedic implan s [157]
Cp-Ti/Ag:NiTi RFMS EIS & PP SBF Passi e laye O hopaedic implan s [102]
Cp-Ti/I O
x
DCMS +elec ochemical
ac i a ion
EIS & CV
d
PBS
e
Passi e laye Neu al elec odes [105]
Cp-Ti/TiO
2
-CuO
x
DCMS +annealing (500 ◦C) EIS & PP SBF Passi e laye – Film densi ica ion O hopaedic and o hodon ic
implan s
[72]
Ti-6Al-7Nb/Pd-PdO DCMS +annealing (up o
650 ◦C)
PP PBS Passi e laye O hopaedic implan s
(join s)
[77]
Ti-6Al-4V/Zn:Z O
2
-
TiO
2
DCMS +mic o-a c oxida ion PP SBF Passi e laye O hopaedic and o hodon ic
implan s
[101]
Ti-6Al-4V/Z -Z O
2
DCMS +mic o-a c oxida ion PP PBS Passi e laye O hopaedic implan s [100]
Ti-6Al-4V/
Z CuFeAlAg
DCMS PP, PS
& EIS A i icial sali a Passi e laye O hodon ic implan s [109]
Ti-6Al-4V/TiSiN Pulsed-DCMS +DCMS PP & EIS SBF (@36.5 ◦C) Passi e laye O hopaedic implan s [110]
Ti-6Al-4V/Ti
x
N
y
DCMS EIS SBF Passi e laye - Film densi ica ion
and la ge g ain sizes
O hopaedic implan s and
neu al elec odes
[111]
Ti-6Al-4V/TiO
2
-
HAp-Al
2
O
3
RFMS +annealing (up o
600 ◦C)
EIS SBF Passi e laye O hopaedic and o hodon ic
implan s
[103]
Ti-6Al-4V/Cu-Ta
2
O
5
DCMS +RFMS PP SBF Passi e laye – Film densi ica ion Implan s [104]
Ti-6Al-4V/Cu-a-C:H DCMS EIS SBF Gal anic O hopaedic implan s [107]
Ti-6Al-4V/TiZ Nb DCMS PP & EIS SBF Passi e laye Implan s [80]
Ti-6Al-4V/Ta-Ti-Z DCMS PP SBF Passi e laye Implan s [81]
Ti-6Al-4V/a-C:H:
SiO
x
PACVD S a ic imme sion 0.9 w % NaCl
solu ion (@ 37 ◦C)
Passi e laye Ca dio ascula de ices
(s en s and al es)
[79]
Ti-6Al-4V/Ta
m
O
n
DCMS PP PBS Pi ing O hopaedic implan s [55]
Ti-6Al-4V/Ti-Z -Ta-
Nb-W +Ag
DCMS PP & EIS PBS (@ 37 ◦C) Passi e laye O hopaedic implan s [112]
Ti-6Al-4V/Ta DCMS PP & EIS SBF Passi e laye O hopaedic implan s [113]
a
Elec ochemical impedance spec oscopy.
b
Po en iodynamic pola isa ion.
c
Simula ed body luid.
d
Cyclic ol amme y.
e
Phospha e bu e solu ion.
Po en ios a ic pola isa ion.
D. San o e al.
Su ace & Coa ings Technology 512 (2025) 132277
7
he en i onmen , among o he s [108].
3.1.3. Mg-based alloys
Magnesium (Mg) and i s alloys a e p omising biodeg adable ma e-
ials o sho - e m medical de ices such as ca dio ascula s en s [115],
o hopaedic implan s [116,117], and empo a y sca olds [84], among
o he s [82]. Low densi y, high speci ic s eng h, and biodeg adabili y
a e desi able cha ac e is ics in a clinical se ing [83]. On he o he hand,
he p incipal d awback o Mg used in body MDs is i s low co osion
esis ance, associa ed wi h he H
2
e olu ion eac ion, causing se e e
medical p oblems in i o [82–84]. Reducing he co osion a e and
keeping he Mg cha ac e is ics would be c ucial o achie ing biocom-
pa ible implan s ha he human body can assimila e, educing he su -
gical p oceedings and, hence, he isks and medical cos s o he
pa ien s. Se e al esea ch eams ha e op ed o coa ings ha could in-
c ease he unc ionali y o Mg and Mg alloys, imp o ing hei essen ial
cha ac e is ics and educing co osion. Table 3 summa ises ecen wo ks
aiming o enhance Mg pe o mance.
Acco ding o Table 3, mos o he coa ings employed in Mg alloys
showed pi ing as he main co osion mechanism. Acco ding o he As-
socia ion o Ma e ials P o ec ion and Pe o mance - AMPP ( o me ly
NACE), his ype o co osion is ini ialised by damage (chemical o
mechanical), de icien o ma ion, o non-uni o mi ies in he su ace
[118]. The las scena io seemed mo e plausible acco ding o he e-
po ed li e a u e. Rough su aces ha m he deposi ed ilms' an ico osion
pe o mance, c ea ing de ec s ha se e as s a ing poin s o pi ing.
Co osion s udies o Mg poin o Mg(OH)
2
as he p ima y co osion
p oduc when in e ac ing wi h di e en simula ed body luids
[78,115,117]. This insoluble co osion p oduc does no ix on he
su ace as quickly as o he oxidised species p oduced du ing co osion in
o he me als. On he con a y, i helps o c ea e mic o-gal anic pai s,
which accele a e he co osion p ocess une enly along he su ace
[82,84]. In his line, a co ec su ace p epa a ion (i.e., polishing,
e ching, chemical cleansing, e ce e a) can help o educe he in luence
o he supe icial de ec s o e he coa ing he e ogenei ies. O he possible
s a egy o apply in MDs based on Mg-alloys could be he implemen a-
ion o dense coa ings applying HiPIMS echnology o inhibi co osion,
as we ha e epo ed in o he ypes o applica ions [85,119].
3.1.4. O he biocompa ible ma e ials
No only alloys based in Fe, Ti o Mg ha e been used as subs a es o
be unc ionalised and used pos e io ly in MDs. Coa ings applied o
polyme s such as UHMWPE (Ul a-high molecula weigh polye hylene)
[120] o polyamide [121] ha e been explo ed in medical applica ions.
Fu he mo e, me allic alloys such as FeMoTaTiZ [122] o CoC Mo
[123] ha e been demons a ed o be biocompa ible, which open he
possibili y o use hem in implan s. He e, coa ings can play an impo an
ole in enla ging hei unc ionalisa ion, simila o he exposed in coa ed
Ti-base alloys. Ano he epo ed ma e ial in biocompa ible applica ions
is Zn, conside ed a nex -gen biodeg adable bioma e ial [124]. P oblems
such as weak ibological pe o mance [120] o poo co osion esis-
ance [125] mus be o e come o conside hese ma e ials sa e o
medical de ices. Table 4 ecapi ula es he di e en ma e ials explo ed
ou o Fe-, Ti- o Mg-based alloys, and wi h he po en ial o become
iable MDs.
As exposed, he coa ings applied by di e en magne on spu e ing
echniques shown su ace passi a ion as he main p o ec ion mechanism
unde simula ed body luid condi ions. This cha ac e is ic is mo e
Fig. 5. Pho os (a and b) and SEM mic og aph (c) o CoC emo al head- ape unde gal anic co osion. The a ows ma k he selec i e dissolu ion, common in
gal anic co osion.
Adap ed om [114].
Table 3
Co osion/p o ec ion mechanisms o coa ings used o unc ionalise Mg-based ma e ials o biomedical de ices.
Subs a e/ ilm Applied echnologies Co osion
es s
Elec oly e P o ec ion/co osion
mechanism
Po en ial
applica ion
Re .
ZK60 alloy/Ta
2
O
5
DCMS EIS & PP SBF Passi e laye O hopaedic
implan s
[82]
AZ91D alloy/H -PLLA DCMS +czoch alski me hod EIS & PP Hank's solu ion (@
37 ◦C)
Pi ing Implan s [83]
MgCa
4
Zn
1
Gd
1
alloy/TiO
2
DCMS +spin coa ing +
annealing (@ 300 ◦C)
PP Ringe 's solu ion Pi ing O hopaedic
implan s
[84]
MgZn alloy/TiO
2
RFMS PP SBF (@ 37 ◦C) Pi ing Ca dio ascula
s en s
[115]
MgCa
2
Zn
1
and MgCa
2
Zn
1
Gd
3
alloys/TiO
2
DCMS PP Ringe 's solu ion (@
37 ◦C)
Pi ing O hopaedic
implan s
[117]
ZEWX and WJK Mg-based alloys (>97 w
%)/CaP and S CaP
RFMS Imme sion SBF (@ 37 ◦C) Pi ing O hopaedic
implan s
[116]
AZ31 alloy/Nb
2
O
5
RFMS EIS & PP SBF (@ 37 ◦C) Pi ing Implan s
( empo a y)
[78]
D. San o e al.
Su ace & Coa ings Technology 512 (2025) 132277
8
ela ed o he composi ion o he coa ings han he p ocessing i sel .
Howe e , magne on spu e ing demons a es i s capaci y o achie e
eliable and di e en high co osion esis an coa ings o di e se sub-
s a es explo ed in MDs. Despi e he ad an ages o his echnology, some
men ioned examples poin ed o he une en elemen al dis ibu ion in he
coa ing, which inc eases he isk o gal anic couples and consequen ly,
comp ises he in eg i y o he MDs [61,79,115]. Ano he impo an
ac o s such as supe icial de ec s, cleaning p ocess o su ace oughness,
can con ibu e o he coa ing e ec i eness in co osion p o ec ion
[84,104,112]. The nex -gen spu e ed coa ings o a oid co osion in
MDs should be ul a-dense, elemen ally uni o m, and chemically s able,
o be assimila ed o he hos wi hou any undesi ed e ec , p io i ising
biocompa ibili y abo e all. As men ioned, o he p oblems associa ed
wi h he subs a e p epa ing and he p ocess i sel mus also be o e -
come o help gain he desi ed cha ac e is ics. O cou se, achie ing all
hese cha ac e is ics is ha d and inding he co ec equilib ium among
hese would be he main challenge.
3.1.5. S a egies agains co osion in MDs
As exposed in he p e ious sec ion, a la ge a ie y o ma e ials ha e
been p o ed p e en co osion in MDs. Fig. 6 exhibi s he po en ial
applica ions o he explo ed op ions. The implan s a e he mos common
esea ch line whe e he coa ings ha e been in es iga ed. In ac , o -
hopaedic implan s ep esen ~53 % o he s udies in coa ings o
co osion inhibi ion in MDs and 1/3 o hese coa ing p esen passi a ion
as he p o ec ion mechanism agains simula ed body luids. Looking o
he coa ing ma e ials, mos o hem a e ansi ion me als oxides and
he e, i is possible o in e applying chemical ine ma e ials is he main
s a egy in coa ing o co osion inhibi ion in MDs. This is expec able
when he componen o be coa ed is exposed cons an ly o luids inside
he human body which a e ha sh o me als. Howe e , his is no he only
employed ac ic o inhibi co osion in MDs. Film densi ica ion
[72,111], po osi y educ ion [97], su pe icial oughness dec ease
[92,98], su ace de ec s diminu ion [98], o coa ing/subs a e adhe -
ence imp o emen [102] ha e been employed as s a egies o con ol
he some o he p oblems wi h co oded MDs. Acco ding o he epo ed
in he li e a u e, he con ol o some deposi ion pa ame e s such as bias
ol age, deposi ion empe a u e/p essu e o he implemen a ion o
echnologies which allow mo e inpu ene gy in he a ge s (i.e., HiPIMS
[123]), can help o imp o e he men ioned cha ac e is ics and b ings a
new ma gin o imp o emen s in coa ings o MDs. Howe e , hese un-
cha e ed app oaches mus be s udied deeply be o e a scale-up om low
Table 4
Co osion/p o ec ion mechanisms o coa ings used o unc ionalise di e en ma e ials o biomedical de ices.
Subs a e/ ilm Applied echnologies Co osion
es s
Elec oly e P o ec ion/
co osion
mechanism
Po en ial applica ion Re .
UHMWPE/Ti, Z & Ta DCMS EIS & PP SBF (@ 36.5 ±0.5 ◦C) Passi e laye O hopaedic implan s
(join s)
[120]
Al2O3, Ti oil, SS oil, Ni-based alloy oil,
P -10%I alloy and glossy ca bon/I O
2
Pulsed-DCMS CV PBS No in o med Neu al elec odes [126]
Glass/Ti-Ag RFMS PP Ringe 's solu ion Passi e laye O hopaedic implan s
(join s)
[127]
Zn/Ti DCMS PP PBS Passi e laye Implan s ( empo a y) [125]
Zn/DLC DCMS PP &
imme sion
PBS Gal anic O hopaedic and
ca dio ascula implan s
[124]
FeMoTaTiZ /HAp-Zn RFMS EIS & PP Fe al bo ine se um Pi ing Bone implan s [122]
CoC Mo/C N-NbN HiPIMS +plasma
glow discha ge
PP Hank's solu ion No in o med O hopaedic implan s [123]
Polyamide/Al:ZnO DCMS EIS & CV Deionised wa e
solu ion wi h DNA
p ime
Di usion Biosenso s [121]
Si/(Z -Ti)(Cu-Ag, Co-Ni) DCMS & RFMS PP & PS PBS Passi e laye Implan s [128]
Si/(TiTaNb, Ti-10Ta-6Nb) DCMS & RFMS PP & EIS SBF (@ 37 ◦C) Passi e laye O hopaedic implan s [129]
Si/NbTaTiVZ (O) RFMS PP 0.1 M HCl solu ion Passi e laye O hopaedic implan s and
su gical ins umen s
[130]
NiTi/Ta
x
O
y
DCMS PP & EIS SBF (@ 37 ◦C) Passi e laye S en s [131]
Fig. 6. Applica ion o spu e ed coa ings o a oid co osion in MDs (le ) and he in o med co osion mechanism o hese in he o hopaedic implan s ( igh ).
D. San o e al.
Su ace & Coa ings Technology 512 (2025) 132277
9
esponses a e no solely dependen on we abili y. Achie ing a delica e
equilib ium be ween he pola and dispe si e componen s o he SFE
becomes impe a i e o ensu e he a achmen o ex acellula ma ix
p o eins o he su ace. Failu e o s ike his balance may esul in he
p e e en ial a achmen o wa e o he su ace, he eby es ic ing he
adhesion o cells. To u he enhance Si-DLC coa ings, adop ing mul i-
laye pe iodic s uc u es wi h al e na ing DLC laye s and hin Si laye s
p esen s a p omising a enue. In compa ison o coa ings composed o a
single laye , o a nanocomposi e wi h andomly embedded addi i es, a
s uc u ed coa ing wi h mul iple laye s o dis inc ma e ials may o e
addi ional ad an ages h ough syne gis ic e ec s [150]. Penko e al.
demons a ed he e icacy o his app oach, e ealing ha a pe iodic
s uc u e comp ising al e na ing nanolaye s o Si and DLC enabled
p ecise con ol o mechanical p ope ies and enhanced biocompa ibili y
o he coa ings [62]. No ably, he s udy ound ha he bias mode and
ol age had negligible e ec s on cell adhesion, emphasizing he signi -
icance o indi idual laye hicknesses. The hickness o DLC laye s
played a pi o al ole, in luencing ha dness and cell adhesion in e sely. A
g ea e DLC hickness esul ed in highe ha dness bu lowe cell adhe-
sion. Con e sely, highe Si hickness imp o ed he cell adhesion bu
comp omised he ha dness, leading o a educed wea esis ance.
S iking a balance be ween hese ac o s, he au ho s de e mined ha
hicknesses o 0.5 nm o Si and 1 nm o DLC laye s we e op imal o
achie ing he desi ed combina ion o mechanical p ope ies and
biocompa ibili y.
In i o s udies ha e e ealed he bio oxici y o Al and V ions
eleased by he Ti-6Al-4 V alloy, which hampe s osseoin eg a ion [161].
To enhance he biological pe o mance o he Ti-6Al-4 V alloy, mono-
laye Ta coa ings, as well as mul i-laye Ti-Z -Ta and Z -Ti-Ta coa -
ings, we e p epa ed using magne on spu e ing on he alloy [81].
Rema kably, he d ople con ac angle on all sample su aces emained
below 90◦, indica ing he hyd ophilic na u e o he coa ings. The hy-
d ophilic su aces, when in con ac wi h blood and biological luids,
os e p o ein adso p ion ha exposes adhesion mo i s, he eby
p omo ing enhanced cell adhesion, p oli e a ion, and di e en ia ion.
This was subs an ia ed by li e/dead cell s aining images o os eoblas
p ecu so cells (MC3T3-E1) cul u ed on he samples o 24, 96, and 168
h, e ealing obus cell p oli e a ion o e ime wi h no obse ed cell
dea h [81]. Fu he mo e, DLC/DLC:Ti nanomul ilaye ilms demon-
s a ed a signi ican educ ion in he elease o ha m ul me als and he
in lamma o y esponse associa ed wi h medical Ti6Al4V p os heses
[114,162].
Z -based hin ilm me allic glasses (TFMGs) ha e ga ne ed signi i-
can a en ion in den al applica ions in ecen yea s. This is a ibu ed o
hei no able capaci y o enhance adhesion, esis e ing, mi iga e
bioco osion, and imp o e o e all biocompa ibili y o ma e ials. A
Z
60.14
Cu
22.31
Fe
4.85
Al
9.7
Ag
3
bulk me allic glass (BG) sys em, ee om
oxic elemen s such as Ni and Be, was deposi ed on o a Ti6Al4V sub-
s a e using a single- a ge magne ic spu e ing me hod [109]. In com-
pa ison o he Ti6Al4V alloy, he cell densi y on he TFMG emains
simila . Howe e , no ewo hy di e ences in cell adhesion mo phology
a e e iden , wi h he TFMG displaying a mo e la ened cell shape and
o e lapping o adjacen cells. This obse a ion sugges s supe io adhe-
sion and heal hy cell g ow h on he biocompa ible TFMG su ace as
opposed o he Ti6Al4V alloy.
3.3.2. S ainless s eels
S ainless s eel (SS) is ex ensi ely employed in he ab ica ion o
ca dio ascula s en s/ al es, o hopaedic p os heses, and a ious o he
biomedical de ices and implan s due o i s ema kable malleabili y and
esis ance o co osion and a igue. Despi e hese ad an ages, implan s
cons uc ed om his ma e ial ace a challenge o limi ed longe i y
unde human physiological condi ions, esul ing in he leaching o me al
ions.
In he ques o op imizing su ace cha ac e is ics, imp o ing esis-
ance agains wea and co osion, and heigh ening biocompa ibili y,
esea che s ha e explo ed he applica ion o ansi ion me al ilms
p o ec i e coa ings (Fig. 9). Examples include NbN [163,164], TiN
Fig. 9. Op imized coa ing s a egies o Ti-based subs a es and s ainless s eel implan s: Tailo ed solu ions o enhance biocompa ibili y, imp o e mechanical pe -
o mance, and mi iga e ad e se e ec s such as ion elease, s ess shielding, and h ombosis isk. C ea ed in h ps://BioRende .com.
D. San o e al.
Su ace & Coa ings Technology 512 (2025) 132277
16

[164], TiO
2
[70], Z O
2
[101], and TiON [165]. These hin ilms ha e
ga ne ed signi ican a en ion due o hei desi able p ope ies,
including high ha dness, good wea esis ance, excellen co osion
esis ance, and high chemical s abili y [91]. The biocompa ibili y, and
abili y o enhance cell p oli e a ion while educing ic ion make i a-
nium aluminum ni ide (Ti-Al-N) one o he mos a o able coa ings o
a ious biomedical applica ions [151]. Addi ionally, niobium oxyni ide
coa ings ha e demons a ed he capaci y o enhance he iabili y o
human ib oblas cells [166], whe eas me al-doped an alum coa ings
con ibu e o a mo e obus an imic obial and biocompa ible p o ile
[167–169]. Poladi e al. conduc ed a s udy o in es iga e he e ec o
a ious CH
4
concen a ions ( anging om 0 o 30 %) on he we abili y
and biocompa ibili y o TaCx ilms deposi ed on SS316L [152]. The
esul s showed ha an inc ease in ca bon con en , esul ing om highe
CH
4
concen a ions, caused phase changes in he coa ings. Ini ially, he
me allic phase ans o med in o a ce amic phase, and e en ually in o
amo phous ca bon. Addi ionally, he inco po a ion o ca bon in he
ilms led o a con inuous dec ease in oughness and we abili y. The
biocompa ibili y es and cell mo phology esul s indica ed ha su ace
modi ica ion signi ican ly imp o ed cell unc ionali y in e ms o cell
adhesion and sp eading. Fu he mo e, he ch omium oxide (C
2
O
3
)
coa ing signi ican ly imp o ed he co osion and wea esis ance,
educed ic ion coe icien , and enhanced biocompa ibili y o he SS.
This imp o emen was e iden as signi ican ly ewe ch omium ions
we e eleased a e imme sion in a saline solu ion [96].
As men ioned abo e, nume ous s udies ha e p o ided subs an ial
e idence ha long- e m implan a ion o SS316L ca dio ascula de ices,
such as s en s, esul s in he gene a ion o oxic me al ions such as Ni, C ,
and Mo wi hin he body. These ions ha e he po en ial o deg ade
cellula s uc u es, igge pla ele ac i a ion, and induce he elease o
pla ele g anules. This cascade o e en s can p omo e coagula ion, al e
pla ele mo phology, and lead o inc eased s ickiness, ul ima ely
con ibu ing o he agg ega ion o pla ele s and he occlusion o small
ascula openings. One p omising app oach o add ess his issue is he
de elopmen o coa ings wi h enhanced blood compa ibili y. As an
example, Pei e al. deposi ed ha nium ca bide (H C) coa ings on 316 L
s eel and subs an ia ed ha me iculous con ol o he bias ol age o e s
a iable pa hway o imp o e he mechanical p ope ies, co osion
esis ance, and hemocompa ibili y o he H C coa ings [95]. The
hemocompa ibili y es esul s un eiled a no ewo hy inding: H C
coa ings p epa ed a bo h -150 V and -200 V showcased supe io
hemocompa ibili y in compa ison o 316 L s eel and he o he wo
coa ings p oduced a bias ol ages o 0 V and -100 V. This ema kable
enhancemen can be linked o he p og essi e dec ease in su ace
oughness and su ace ene gy as he bias ol age exceeded -150 V.
Consequen ly, hese coa ings we e ende ed mo e sui able o in e ac-
ion wi h blood componen s. Fu he mo e, he H C coa ing gene a ed a
a bias ol age o -200 V exhibi ed ou s anding co osion esis ance,
a ibu ed o i s smoo he su ace, imp o ed adhesion, dense s uc u e,
and he lowes coe icien o ic ion agains phospha e bu e solu ion
(0.14).
3.3.3. Biodeg adable me al subs a es
Biodeg adable me als, such as magnesium, zinc, and i on, a e highly
ega ded as nex -gene a ion bioma e ials o a ious biomedical appli-
ca ions [170]. These me als possess desi able p ope ies ha make hem
sui able candida es o use in medical implan s and de ices. They exhibi
excellen biocompa ibili y, mechanical s eng h, and he abili y o
deg ade o e ime wi hin he physiological en i onmen . This biodeg-
ada ion p ocess elimina es he need o implan emo al su ge ies,
educing pa ien discom o and po en ial complica ions. Addi ionally,
hese me als ha e been shown o p omo e issue egene a ion and ha e
po en ial he apeu ic e ec s, making hem p omising ma e ials o
u u e biomedical ad ancemen s [171]. Ne e heless, i is impo an o
acknowledge ce ain limi a ions associa ed wi h hese ma e ials. Spe-
ci ically, hei s eng h and duc ili y migh all sho o mee ing he
demands o load-bea ing implan s, pa icula ly in applica ions such as
ca dio ascula and o hopaedic se ings. In addi ion, cells exhibi a
ela i ely low ole ance agains Zn ions and a Zn concen a ion o 6.5
ppm can do se e e damage o endo helial cells. To add ess his limi a-
ion and enhance he biomechanical pe o mance o zinc implan s,
su ace modi ica ions such as i anium coa ings [125], oxide laye s
[172], and i anium oxyni ide coa ings [117] ha e been s a egically
deposi ed. Fo ins ance, a smoo h-su aced i anium oxide coa ing,
measu ing 400 nm in hickness and composed o dense amo phous TiO
2
nanopa icles, was me iculously deposi ed on o he MgZn subs a e. The
applica ion o his coa ing no ably enhanced he co osion esis ance o
he MgZn alloy. A e a 14-day imme sion in simula ed body luid (SBF),
he TiO
2
-coa ed sample exhibi ed less co osion compa ed o he un-
coa ed subs a e. In e ms o blood compa ibili y, he uncoa ed Mg al-
loys induced se ious hemolysis and pla ele agg ega ion, while he TiO
2
-
coa ed sample demons a ed a hemolysis a io o <1 % and exhibi ed
supe io an i-pla ele adhesion. Fu he mo e, he TiO
2
-coa ed MgZn
alloy demons a ed lowe cy o oxici y, wi h endo helial cells a aching
well o he su ace, indica ing excellen cy ocompa ibili y [115].
3.3.4. O he biocompa ible ma e ials
In addi ion o he con en ional ma e ials commonly employed in
biomedical de ices, highligh ed ea lie , su ace enginee ing modi ica-
ions ha e also been ex ended o polyme ic subs a es, high-en opy
alloys, and bulk me allic glasses [128] o enhance hei
biocompa ibili y.
High-en opy alloys (HEA) ha e a isen as a key class o ad anced
ma e ials o bioma e ials applica ions. Cemin e al. use a nea -
equimola combina ion o Nb, Ta, Ti, V, and Z ansi ion me als o
design a high-en opy amo phous coa ing, demons a ing supe io in
i o biocompa ibili y wi h bone cells [130]. The ema kable in i o
biocompa ibili y o his coa ing, compa ed o i s polyc ys alline HEA
p o o ype and he Ti (con ol) coa ing, can be a ibu ed o ac o s such
as ma e ial su ace uni o mi y, smoo hness, a s able chemical s a e,
educed concen a ion o anadium, and enhanced co osion esis ance.
In con as o hei con en ional c ys alline me allic coun e pa s,
bulk me allic glasses (BMGs) ha e unique amo phous s uc u es,
esul ing in heigh ened s eng h, a lowe Young's modulus, imp o ed
wea esis ance, obus a igue endu ance, and excellen co osion
esis ance. These dis inc i e a ibu es ha e gene a ed conside able in-
e es in he biomedical ield, es ablishing BMGs as highly p omising
ma e ials wi h e sa ile applica ions [173]. To de e mine excellen
ea u es o Z -based me allic glasses o bioimplan s, no el qua e na y
sys ems, namely Z
40
Ti
37
Co
12
Ni
11
and Z
50
Ti
32
Cu
13
Ag
5
, we e ab ica ed
using he magne on co-spu e ing echnique [128]. Elec ochemical
e alua ions e ealed supe io co osion esis ance in Z
50
Ti
32
Cu
13
Ag
5
and Z
40
Ti
37
Co
12
Ni
11
me allic glasses, sugges ing hei e icacy in p e-
en ing ad e se biological eac ions. Fu he mo e, he qua e na y
me allic glasses exhibi ed subs an ial su ace ee ene gy, signi ying
enhanced cell in e ac ion wi h he implan su ace. Cy ocompa ibili y
assessmen s ia MTS assay e ealed minimal oxici y owa ds MC3T3-
E1 p eos eoblas cells.
In conclusion, PVD coa ings play a pi o al ole in enhancing he
biocompa ibili y o medical de ices by suppo ing cell adhesion, p o-
li e a ion, and di e en ia ion, while mi iga ing immune esponses and
limi ing ion elease. Applied o bo h con en ional subs a es like i a-
nium and s ainless s eel, as well as eme ging ma e ials such as biode-
g adable me als, high-en opy alloys, and me allic glasses, hese
coa ings o e e sa ile unc ionaliza ion. Tailo ed coa ings such as TiN,
TiO₂, and DLC signi ican ly imp o e hemocompa ibili y and supp ess
immune ac i a ion, whe eas mul ilaye sys ems like Z -Ti-Ta p omo e
os eoblas adhesion and minimize cy o oxic e ec s.
3.3.5. Ad ancing biocompa ibili y es ing: b idging he gap be ween in i o
and in i o models
To e alua e he biocompa ibili y o bioma e ials, i is essen ial o
D. San o e al.
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17
pe o m a se ies o es s ollowing he guidelines se by egula o y o -
ganiza ions. O e he yea s, he e ha e been adap a ions o he e-
qui emen s and es s ha de e mine he biocompa ibili y o ma e ials,
such as he ISO 10993-Pa 22: Edi ion 1 s anda d, which aligns wi h
FDA guidelines [174]. The limi a ions o se e al in i o me hods used o
es bioma e ials a e e iden as hey ail o accu a ely eplica e he dy-
namic and complex physiological condi ions ound in he human body.
The in i o en i onmen is cha ac e ized by cons an ly changing luids
and cellula in e ac ions, which canno be ully cap u ed in s a ic in
i o es s. As a esul , i is c ucial o acknowledge hese limi a ions and
explo e al e na i e app oaches ha can be e simula e he in i o
condi ions when e alua ing he biocompa ibili y o bioma e ials. 3D in
i o models a e eme ging as a mo e ealis ic ep esen a ion o issue, o
o gans compa ed o 2D models. These 3D models p o ide a mo e ac-
cu a e p edic ion o a ious p ocesses, such as cell p oli e a ion o
ib osis, in he p esence o implan s. Fu he mo e, he de elopmen o
bioin o ma ic models ha allows he compa ison be ween cy o oxici y
da a ob ained om di e en esea ch g oups i s c ucial [175].
3.4. Fos e ing osseoin eg a ion
Bioma e ials used in o hopaedic applica ions mus mee a ious
s uc u al, mechanical, and biological c i e ia because o hei essen ial
ole in he bone egene a ion p ocess [176].
.
Rega ding hei biological
cha ac e is ics, i is c ucial o conside he biocompa ibili y, os eo-
conduc i i y, and os eoinduc i i y. Biocompa ibili y, as men ioned
abo e, e e s o he ma e ial's abili y o elici an app op ia e hos
esponse wi hou any ad e se e ec s such as cy o oxici y, mu agenesis,
ca cinogenesis, immunogenici y, o geno oxici y. Os eoconduc i i y
ep esen s he bioma e ial's capaci y o p omo e cell adhesion, p oli -
e a ion, and he o ma ion o he bone ex acellula ma ix (ECM) by
os eoblas s, he eby suppo ing bone g ow h. Os eoinduc i e bio-
ma e ials a e highly desi able as hey can induce he di e en ia ion o
mesenchymal s em cells in o os eoblas s, which a e esponsible o bone
o ma ion. Al oge he , hese p ope ies indica e he ma e ial's bioac-
i i y and a e c i ical o success ul osseoin eg a ion o he implan wi h
he hos issue [177]. E ec i e osseoin eg a ion indica es he implan 's
capaci y o o m bone-like apa i e c ys als on hei su aces and es ablish
a di ec connec ion wi h he su ounding hos bone issue wi hou he
o ma ion o undesi able ib ous issue.
Bioma e ials used in bone issue enginee ing a e commonly ca ego-
ized in o polyme ic, ce amic, me allic, and composi e ma e ials.
Among hese, me allic bioma e ials such as i anium and i s alloys,
s ainless s eel, cobal , magnesium and i s alloys, nickel– i anium alloy
(ni inol), and an alum a e widely used in bone implan s. Despi e he
se e al ad an ages o me allic bioma e ials, hese ma e ials can be
cy o oxic due o co osion when exposed o complex physiological
condi ions wi hin he body and a e biologically ine . This inhe en
cha ac e is ic p esen s challenges o i s success ul in eg a ion wi h
bone issue ollowing implan a ion, esul ing in p olonged pos ope a i e
healing ime and po en ial complica ions, including implan loosening
and ailu e. These issues can signi ican ly impac he o e all success and
longe i y o he implan , emphasizing he need o imp o ed s a egies
o enhance he bioac i i y and osseoin eg a ion o implan s o imp o e
pa ien ou comes (Fig. 10).
3.4.1. Ti-based o alloyed subs a es
Calcium phospha e (CaP) bioma e ials sha e simila i ies wi h bone
Fig. 10. The osseoin eg a ion p ocess and i s challenges. The diag am illus a es he key s ages o osseoin eg a ion, s a ing wi h p o ein adso p ion (1), ollowed by
he in lamma o y esponse (2), os eogenic cell adhesion (3), and concluding wi h angiogenesis and os eogenesis. Common me allic bioma e ials such as i anium,
s ainless s eel, and magnesium alloys ace signi ican challenges, including co osion and biological ine ness. These limi a ions esul in p olonged healing, implan
loosening, and po en ial implan ailu e, unde sco ing he need o enhanced bioac i i y. Ad anced coa ing echnologies, such as calcium phospha e, an alum,
ca bon-based, and me al oxide coa ings, a e highligh ed as e ec i e solu ions. These coa ings imp o e bioac i i y, enhance cell adhesion and os eoblas di e en-
ia ion, p o ide an ibac e ial p ope ies, and inc ease co osion esis ance, ul ima ely suppo ing success ul osseoin eg a ion and imp o ing implan pe o mance.
C ea ed in h ps://BioRende .com.
D. San o e al.
Su ace & Coa ings Technology 512 (2025) 132277
18
mine als in e ms o biodeg adabili y, bioac i i y, and os eo-
conduc i i y. In addi ion, he applica ion o CaP-based coa ings on
me allic implan s p o ides enhanced co osion esis ance, minimizing
he elease o me al ions in o he implan a ion si e [178]. This u he
con ibu es o he o e all success o he implan by educing po en ial
ad e se e ec s and p omo ing a mo e a o able healing en i onmen .
The e o e, bioma e ials, pa icula ly me allic implan s, a e usually
coa ed wi h a laye o CaP such as hyd oxyapa i e (HAp),
Ca
10
(PO
4
)
6
(OH)
2
, icalcium phospha e (TCP), o CaP glass-ce amics o
enhance he osseoin eg a ion. Biphasic calcium phospha e (BCP), which
consis s o hyd oxyapa i e (HA) and be a- icalcium phospha e (β-TCP),
is mainly used in a i icial oo h and bone implan s due o highe p o ein
adso p ion and os eoinduc i i y compa ed o HA alone. To ob ain a
be e unde s anding and applica ions o BCP ilms, RF magne on
spu e ing was used o deposi BCP ilms on Ti-6Al-4 V.[179]. The in
i o bioac i i y esul s showed small globula and ellip ical like s uc-
u es on he su ace o all BCP ilms a e 14 days o SBF imme sion,
which indica es he coa ing ilms possess bioac i i y.
Tan alum has ga ne ed signi ican in e es as bo h a po ous bulk
ma e ial and a coa ing o implan s, pa icula ly in he ield o o ho-
pedics [180]. This me al possesses se e al p ope ies ha make i highly
appealing o such applica ions, including excep ional co osion esis-
ance in body luids, imp o ed os eoconduc i i y, and supe io esis-
ance o bac e ial adhe ence compa ed o i anium. Ba kowiak e al.
in es iga ed he con ibu ion o a p o ec i e an alum in e laye
deposi ed on i anium subs a es on he g ow h o HAp c ys als wi h
hyd o he mal syn hesis me hod [181]. The diame e o HAp c ys alli es
may be con olled and d i en by na u e o he in e laye ( an alum,
an alum oxide o i anium oxide) p e iously o med on he i anium
subs a e. Coa ings wi h smalle diame e s o HAp c ys als (be ween 0.3
μ
m and 0.6
μ
m) syn hesized on an alum-based ilms we e ound o be
mo e a o able o cell iabili y and a achmen . Simila ly, Cheon e al.
e ealed ha he in oduc ion o a Ta implan ed laye , app oxima ely
10 nm in hickness, on o he uppe mos su ace o poly(e he imide),
esul ed in sus ained su ace hyd ophilici y and c ea ed an ad an a-
geous en i onmen conduci e o he adhesion, p oli e a ion, and di -
e en ia ion o MC3T3-E1 p e-os eoblas s [182].
O e he las ew yea s, a wide a ay o ca bon-based composi es has
been ex ensi ely explo ed and esea ch has consis en ly shown ha he
inclusion o addi ional elemen s can ma kedly enhance hei o e all
mechanical and biological cha ac e is ics [183]. Milan e al. showed he
po en ial o Cu/a-C:H hin coa ings, pa icula ly hose wi h an op imal
combina ion o 36.8 w % coppe con en and a sp
2
/sp
3
a io o 4, as
p omising candida es o imp o e he mechanical and ibological
p ope ies and enhance osseoin eg a ion o Ti-6Al-4 V-based implan s
[107]. The e ec o DLC laye s wi h di e en con en o C on he
adhesion and os eogenic di e en ia ion o human os eoblas -like Saos-2
cells was also assessed in i o [184]. The au ho s conclude ha highe
concen a ions o ch omium suppo ed cell adhesion; howe e , DLC and
DLC doped wi h a lowe concen a ion o ch omium suppo ed os eo-
genic cell di e en ia ion. Simila ly, he inco po a ion o Ca nano-
pa icles no only enhanced he mechanical a ibu es o he a-C ilm bu
also no ably o i ied i s adhesion o os eoblas s [185]. In an al e na i e
app oach, g adien mul ilaye s composed o Ti and C we e deposi ed
on o a i anium alloy subs a e using MS [57]. The esul ing coa ing
demons a ed imp o ed we abili y o he Ti alloy su ace, leading o
enhanced p oli e a ion and adhe ence o os eoblas cells.
Silicon-con aining ma e ials ha e also ga ne ed a en ion o hei
abili y o s imula e he p oli e a ion and di e en ia ion o human
os eoblas -like cells. One no able example is he use o silica e-based
bioac i e glasses, which elease ionic dissolu ion p oduc s ha ha e
been shown o signi ican ly enhance cell p oli e a ion and os eogenic
di e en ia ion [186]. Ti anium silicon ni ide (TiSiN) hin ilms ha e
demons a ed hei po en ial in p omo ing he di e en ia ion o human
bone cells, su passing he pe o mance o he ba e con ol Ti alloy [110].
This was e idenced by he inc eased p oduc ion o alkaline phospha ase
and calcium. Mo eo e , TiSiN hin ilms o e imp o ed co osion
esis ance, e ec i ely p o ec ing he unde lying me al om he ha m ul
e ec s o he co osi e en i onmen .
Me al oxide coa ings, including TiO
2
, Z O
2
, Nb
2
O
5
, VO
2
and Ta
2
O
5
,
o e g ea po en ial as coa ings o o hopaedic and den al implan s
[187]. These coa ings possess nume ous bene icial p ope ies, such as
hei ema kable osseoin eg a ion abili y, abili y o enhance cell adhe-
sion and p oli e a ion, educe in lamma o y esponse, and exhibi
an ibac e ial p ope ies [189]. Addi ionally, hey demons a e excellen
co osion and wea esis ance [190]. Ho andghadim e al. es ablished a
no ewo hy co ela ion be ween he concen a ion o Ta
2
O
5
in HAp-
Ta
2
O
5
coa ings and wo i al ac o s in bone issue enginee ing:
os eoblas -like cell a achmen and he g ow h o bone-like apa i e
[191]. This in es iga ion unde sco es ha as he Ta
2
O
5
con en in-
c eases, so does he p opensi y o cellula adhesion and he o ma ion o
apa i e esembling na u al bone. Building upon hese indings, Wang
e al. ex ended he explo a ion o i anium nano ubes coa ed wi h Ta
2
O
5
,
e ealing subs an ial imp o emen s in cell adhesion, iabili y, enhanced
calcium deposi ion, and he exp ession o key os eogenic genes when
compa ed o uncoa ed nano ubes [192]. Consis en ly, ou g oup [193]
and Huang e al. [194] co obo a ed hese obse a ions by epo ing
heigh ened iabili y o MC3T3 cells, human skin ib oblas s, and human
os eosa coma MG-63 cells when cul u ed on Ta
2
O
5
-coa ed su aces in
compa ison o ba e i anium subs a es. Acco ding o Liz´
a aga e al.,
Z O
2
ep esen ed a po en ial al e na i e o TiO
2
, since Z O
2
ilms p o-
mo ed highe adhesion o MG63 cells, and had highe co osion esis-
ance due o hei highe elec ochemical s abili y and su ace in eg i y
compa ed o TiO
2
[195].
The applica ion o a s on ium i ana e (S TiO
3
) nanopa icles
coa ing on i anium su aces has shown ema kable po en ial in
enhancing adhesion, p oli e a ion, and os eogenic di e en ia ion o
MC3T3-E1 cells [196]. To enhance he os eogenesis and an ibac e ial
e iciency simul aneously, a new double-laye s a egy ( he p eceden
Ag nanopa icle laye and he o e laying S TiO3 laye ) h ough wo-s ep
magne on spu e ing was de eloped [197]. Ch is ensen e al. demon-
s a ed in a abbi model ha he elease o s on ium (S ) om a
Ti–S –O-coa ed implan di uses o e se e al hund ed mic ons in o he
su ounding bone issue [198]. This di usion was e iden h ough he
no iceable ele a ion in he S /Ca a io, and hese indings sugges he
po en ial o S TiO o enhance osseoin eg a ion. Simila ly, Li e al.
showed ha a subs an ial p opo ion o ilopodia and ac in ibe s dis-
played op imal os eogenic p ope ies among MC3T3-E1 cells cul u ed
on Z O
2
/S subs a es [199]. Fu he mo e, he Z O
2
/S coa ing exe ed a
signi ican up egula ion in he exp ession o mul iple os eogenic- ela ed
genes, including Runx2, COL-1, ALP, OPG, OPN, and OCN. These ind-
ings collec i ely es ablish highly a o able condi ions o he p oli e a-
ion and g ow h o os eoblas cells.
3.4.2. Mg-based subs a es
Magnesium (Mg) and i s alloys ha e a ac ed conside able esea ch
in e es as p omising ma e ials o egene a ion and suppo o unc-
ional bone issue due o hei ligh weigh na u e, in i o deg ada ion,
and mechanical p ope ies ha mimic na u al bone [200]. Fu he mo e,
Mg is an essen ial elemen o me abolic p ocesses in he human body
and is p edominan ly ound in bone issue. I s imula es he p oli e a ion
o bone cells and p omo es bone egene a ion. Despi e being a new class
o biodeg adable me allic ma e ials wi h po en ial o hopaedic appli-
ca ions, hei limi ed os eoinduc i e p ope ies ha e hinde ed hei
widesp ead use. The e o e, he su ace modi ica ion o Mg-based ma-
e ials plays a c ucial ole in imp o ing cellula esponse while p ese -
ing desi able mechanical p ope ies and enhancing os eogenic
p ope ies. In a s udy conduc ed by Cao e al., a composi e coa ing o
luo ina ed hyd oxyapa i e (FHA) and Ta was de eloped on he su ace
o a Mg alloy using he mal syn hesis and magne on spu e ing ech-
nologies [201]. The esul s o he s udy showed ha he nano-needle
s uc u e o he FHA coa ing signi ican ly inc eased he su ace
D. San o e al.
Su ace & Coa ings Technology 512 (2025) 132277
19
oughness o he Mg alloy, while he Ta coa ing dec eased he su ace
oughness and imp o ed hyd ophilici y. In i o biological analysis
con i med ha he FHA coa ing enhanced cell iabili y and p omo ed
os eogenic p ope ies on he Mg alloy su ace. The FHA coa ing acili-
a ed a o able in e ac ions wi h cells, suppo ing hei g ow h and
di e en ia ion. Fu he mo e, he elease o Ta ions om he coa ing
demons a ed an ibac e ial e ec s by educing bac e ial adhesion.
3.4.3. O he subs a es
Codescu e al. de ised a no el FeMoTaTiZ high-en opy alloy (HEA)
h ough a acuum a c emel ing p ocess. They subsequen ly applied a
zinc-doped HAp coa ing o i s su ace using MS. This inno a i e
app oach aimed o syne gize os eogenic and an imic obial p ope ies
wi hin he ma e ial [122]. Jang e al. coa ed polye he e he ke one
(PEEK) ilamen s ein o ced wi h in e nal TiO
2
nanopa icles wi h HAp
using RFMS [202]. The ha dness, ensile, comp ession s eng hs, and
sc a ch es esul s demons a ed a conside able enhancemen in he
mechanical s eng h o he hie a chical PEEK/TiO2/HAp hyb id com-
posi e s uc u e compa ed o ha o he con en ional 3D-p in ed PEEK.
In addi ion, his hyb id composi e s uc u e imp o ed he p oli e a ion
and di e en ia ion o MC3T3–E1 bone cells, whe eas he ex e nal HA
coa ing led o a mo e p e alen os eoblas abso p ion. Simila ly, Xin
e al. showed a mo e a o able cell adhesion and os eogenic di e en i-
a ion o PEEK su aces which we e encapsula ed wi h amo phous HAp.
[203] Fu he mo e, as a p oo o concep , he PEEK/TiO2/HAp hyb id
composi e was success ully inse ed in o he emu o abbi s in i o,
and new bone egene a ion wi hou in lamma ion o in ec ion in he
con ac a ea was egis e ed e en a e 1 mon h.
NiTi alloy s ands ou as a p e e ed choice o e con en ional implan
ma e ials such as s ainless s eel, cobal -based alloys, and i anium alloys
ac oss a b oad spec um o medical applica ions [204]. This p e e ence
a ises om he alloy's excep ional supe elas ic and shape memo y
p ope ies. Fo ins ance, i is widely used in den al a chwi es and ca -
dio ascula s en s, whe e i s capaci y o wi hs and de o ma ion and
p omp ly e e o i s o iginal shape is in aluable. Fu he mo e, i s
unique shape memo y p ope ies ind ex ensi e use as bone s aples o
apid ixa ion o ac u ed bones, he eby accele a ing he healing p o-
cess [205]. Mo eo e , NiTi alloy has ecen ly gained ecogni ion as a
p omising ma e ial o o hopaedic implan s and bone subs i u es [206].
This is p ima ily due o i s compa a i ely lowe elas ic modulus and
s i ness when compa ed o adi ional me allic bioma e ials. These a -
ibu es play a pi o al ole in minimizing s ess shielding e ec s,
educing bone eso p ion, and lowe ing he isk o b i le bone and
implan ailu e. None heless, he u iliza ion o NiTi alloy as a long- e m
implan emains a subjec o deba e, p ima ily a ibu ed o i s ele a ed
nickel (Ni) con en and he associa ed isk o alle gic and ad e se e-
ac ions s emming om he elease o nickel in o he su ounding en i-
onmen . To ackle his conce n, A. Mo allebzadeh deposi ed a
e ac o y high-en opy alloy (RHEA) ilm comp ised o TiZ TaNbH ,
wi h hicknesses measu ing 750 and 1500 nm, on o a NiTi alloy sub-
s a e [207]. Subsequen ly, an ex ensi e compa ison was conduc ed
be ween his RHEA ilm and a he mally g own TiO
2
ilm, ocusing on
hei mechanical p ope ies and in i o biocompa ibili y. The esul s
om he HAp o ma ion es s, conduc ed in simula ed body luid o e
a ying soaking ime pe iods, demons a ed a signi ican ly as e a e o
HAp o ma ion on he RHEA ilms in compa ison o bo h he he mally
g own TiO
2
and he uncoa ed NiTi subs a e. This enhanced bioac i i y
and he o ma ion o bone-like HAp on he RHEA ilm's su ace can be
a ibu ed o he p esence o oxides o cons i uen elemen s, especially
TiO
2
, Ta
2
O
5
, and Z O
2
[208]. Fu he mo e, he RHEA ilm-coa ed
specimens exhibi ed a oxic Ni ion elease ha was app oxima ely hal
an o de o magni ude lowe han ha o he he mally g own TiO
2
-
coa ed specimens, which can be pa ially explained by hei sc a ch
esis ance and high adhesion s eng h.
3.4.4. Rela ionship be ween osseoin eg a ion and su ace p ope ies o
coa ings
Os eogenic cell di e en ia ion can be in luenced no only by he
chemical composi ion o he ma e ial su ace, bu also by he su ace
mic o/nano- oughness, we abili y, s i ness, and elec ic conduc i i y
[209,210] (Fig. 11).
Cells a e highly esponsi e o mic o- opog aphy and can o ien and
mig a e based on he unde lying mic os uc u al ea u es. The ough-
ness o a su ace can impac cell a achmen , p oli e a ion, and di e -
en ia ion. A su ace ende ed wi h 25-
μ
m pa icles c ea es a oughness
ha is compa able o he size o he cells hemsel es. Con e sely, when
coa se pa icles a e assembled, he esul ing oughness is la ge enough
ha os eoblas cells do no pe cei e i as ough anymo e. Ins ead, hese
mac o- ough su aces appea locally smoo h o he cells. On such
smoo h su aces, cells can a ach and p oli e a e, bu hey end o exhibi
ela i ely low le els o di e en ia ion. In a s udy conduc ed by Sui e al.,
i was shown ha he 5-day cell adhesion densi y on a nano-s uc u ed
Ta laye was 1.26 imes highe han uncoa ed Ti6Al4V and 1.32 imes
highe han pu e an alum. The nano-s uc u ed Ta laye , wi h i s
inc eased su ace oughness compa ed o he uncoa ed subs a e, played
a signi ican ole in imp o ing he ini ial adhesion o MC3T3-E1 cells
[113]. Likewise, he c ys alline be a-Ta
x
O
5
coa ing, which exhibi ed he
highes oughness and su ace ene gy alues, posi i ely in luenced cell
sp eading and mo phology. These indings highligh he po en ial o
using such su ace ea men s o enhancing he pe o mance o
i anium-based implan s [54]. On he o he hand, su aces wi h mic o-
s uc u al oughness, ypically wi h an a e age oughness o 4-7
μ
m,
a e mo e a o able o cell di e en ia ion [212].
The in luence o su ace opog aphy on cell adhesion and mig a ion
has ga ne ed signi ican in e es a he in e sec ion o mic obiology,
su ace science, and ma e ial science. Ta
2
O
5
su aces ha e been de el-
oped wi h good biocompa ibili y, and hei nano- opog aphy plays a
c ucial ole in egula ing os eoblas adhesion. The su aces wi h con ex
nano-cu a u e a e c ea ed by applying eac i e magne on spu e ing
o an alum o e sub-monolaye s o hyd oca bon plasma polyme pa -
icles [213]. Subsequen ul asonica ion emo es he pa icles om he
coa ings, esul ing in su aces wi h conca e nano-cu a u e. P ima y
human os eoblas s ha e been ound o main ain iabili y and mine al-
iza ion abili y on all ypes o hese su aces. Howe e , Ta
2
O
5
su aces
wi h conca e opog aphy exhibi es ained adhesion o he cells. The
limi ed cell adhesion can be a ibu ed o he closed na u e o he
conca e ca i ies, which pose addi ional po en ial ba ie s o p o ein-
media ed cell-su ace in e ac ions. Zapa a e al. showed ha he
mouse mesenchymal s em cells adhesion o Ti6Al4V was a o ed bo h
by he inco po a ion o he HAp-Si mul ilaye coa ing and by he in-
c ease in he oughness o he subs a e (27 ±5 nm o 52 ±6 nm) [214].
Simila ly, HAp-coa ed TiO2 nano ubes showed signi ican ly inc eased
su ace oughness and dec eased wa e con ac angle, which p o ided
an enhanced cell a achmen and g ow h when compa ed o as-anodized
TiO
2
nano ubula and pu e CP-Ti su aces [211]. Nano opog aphy su -
ace modi ica ions ha e been employed in den al implan s o enhance
osseoin eg a ion immedia ely a e implan a ion. In a s udy compa ing
wo di e en nano opog aphy su ace implan s, he e ec s o osseoin-
eg a ion ollowing oo h ex ac ion we e e alua ed [215]. One implan
ea u ed TiO
2
nano ubes (NT-TiO
2
) c ea ed h ough anodiza ion, while
he o he had a nano opog aphy su ace wi h s on ium (NT-S ) depos-
i ed using magne on spu e ing echnology. Resul s demons a ed ha
he NT-TiO
2
su ace exhibi ed nano ubes wi h diame e s anging om
15 o 80 nm, whe eas he NT-S g oup displayed nanopa icles
measu ing 20 o 40 nm deposi ed on he su ace. The NT-S su ace
exhibi ed supe io in e acial bonding s eng h compa ed o he NT-TiO
2
g oup. Fu he mo e, he NT-S g oup displayed g ea e bone o ma ion,
highe bone- o-implan con ac , and maximum pull-ou o ce. These
indings sugges ha while he NT-TiO
2
su ace exhibi ed a o able in
i o bioac i i y, he NT-S su ace, wi h i s highe in e acial bonding
s eng h, demons a ed supe io in i o os eogenesis.
D. San o e al.
Su ace & Coa ings Technology 512 (2025) 132277
20
To enhance he e ec i eness o coa ings in p omo ing cell g ow h
and os eoin eg a ion, addi ional s a egies can be explo ed. One such
app oach is he inco po a ion o g ow h ac o s, such as bone mo pho-
gene ic p o eins, wi hin he coa ing. This can signi ican ly enhance cell
g ow h and di e en ia ion, leading o imp o ed ou comes in issue
in eg a ion [216], [217].
Concluding his sec ion, PVD coa ings en iched wi h bioac i e ma-
e ials and nano-s uc u ed su aces signi ican ly enhance osseoin e-
g a ion, especially in o hopaedic and den al implan s. While
con en ional me als like i anium and s ainless s eel a e mechanically
obus , hei bioine na u e can hinde bone healing. Coa ings such as
calcium phospha e, an alum, and TiO₂ imp o e os eoconduc i i y and
co osion esis ance. Addi i es like s on ium, luo ine, o g ow h ac-
o s u he boos bone egene a ion, ensu ing long- e m implan
s abili y.
3.5. Boos ing an imic obial ac i i y
Nosocomial in ec ions caused by mul id ug- esis an pa hogens a e a
signi ican conce n in public heal h se ings. The ise o mul id ug-
esis an bac e ia in communi y-acqui ed in ec ions is also ala ming.
Bio ilm o ma ion on bioma e ials con ibu es o ch onic in ec ions ha
a e di icul o e adica e and ha e led o inc eased mo ali y a es [60].
Immuno-comp omised hospi alized and elde ly pa ien s a e pa icula ly
ulne able, wi h implan -associa ed in ec ions (IAIs) accoun ing o
nea ly 60 % o hospi al-acqui ed in ec ions [218]. The inc easing a i-
e y and use o medical de ices, including u ina y and ascula ca he e s,
as well as o hopaedic de ices, ha e u he inc eased he isk o de ice-
associa ed in ec ions due o he physical and chemical s uc u e o
o eign bodies ha can acili a e mic obial adhe ence [219].
Bio ilms a e dynamic ecosys ems composed o a polyme ic ma ix
ha houses a di e se ange o species engaged in social in e ac ions.
Compa ed o plank onic bac e ia, bac e ia wi hin bio ilms a e inc edibly
esilien , being 1000 ime mo e esis an o an ibac e ial d ugs [220].
This no only makes an ibio ics less e ec i e in ea ing in ec ions
caused by bio ilms bu also con ibu es o he g owing p oblem o bac-
e ial esis ance. Among he pa hogenic bac e ia ha cause IAIs, he
G am-posi i e S aphylococcus au eus is he mos widely s udied [221].
O he pa hogenic bac e ia ha can cause IAIs include G am-nega i e
Pseudomonas ae uginosa, Po phy omonas gingi alis, and Esche ichia coli
and G am-posi i e S aphylococcus epide midis and S ep ococcus sangui-
nis. As a esul , he e has been a ecen emphasis on su ace modi ica ion
and he de elopmen o no el coa ings o comba bio ilm o ma ion,
educing he need o an ibio ics.
The bio ilm o ma ion p ocess begins wi h he a achmen o mi-
c oo ganisms o he su ace o he bioma e ial, ollowed by he accu-
mula ion o laye s and he subsequen g ow h and sp eading o
mic obial cells. I is impo an o no e ha only he ini ial a achmen o
bac e ia is e e sible du ing his p ocess. The e o e, he p e en ion o
ini ial bac e ial a achmen o he implan su ace is c ucial o inhib-
i ing bio ilm o ma ion. To add ess his challenge, he applica ion o
an imic obial coa ings on ma e ial su aces has eme ged as a signi ican
s a egy [222] (Fig. 12). The p ope ies o a su ace, including chemical
composi ion, oughness, and we abili y, play a pi o al ole in bac e ial
adhesion and agg ega ion. By ca e ully manipula ing hese su ace
cha ac e is ics, i becomes possible o in luence he a achmen beha io
o bac e ia and he subsequen o ma ion o bio ilms [223]. These ad-
ancemen s hold g ea po en ial o enhancing he pe o mance and
longe i y o implan s, he eby imp o ing pa ien ou comes in a ious
medical applica ions.
Hyd ophobic coa ings ha e been ound o be e ec i e in p e en ing
bac e ial adhesion ini ially, bu o e ime, hey can p omo e bac e ial
adhesion. Fo example, Z
–
C coa ings we e deposi ed on 304 L s eel
using eac i e magne on spu e ing in an A -C
2
H
2
a mosphe e wi h
a ying ace ylene low a es [65]. Di e en a omic ca bon concen a-
ions in he coa ings we e achie ed, anging om 21 o 79 a . %.
Fig. 11. Schema ic ep esen a ion o he ela ionship be ween osseoin eg a ion and su ace p ope ies o coa ings. Key su ace p ope ies include Su ace Chemical
Composi ion, Su ace Topog aphy and We abili y. As example, images on he igh illus a e nano- oughness e ec s, u he enhancing adhesion and os eogenic
di e en ia ion [211]. Saos-2 cells on he ba e CP-Ti exhibi ed a quasi- ound shape wi h small ilopodia, indica ing poo cell sp eading and adhesion. In con as , Saos-
2 cells on HA-coa ed su aces we e s ongly a ached, displaying a polygonal mo phology wi h abundan elonga ed ilopodia, highligh ing he enhanced biocom-
pa ibili y o he HA-coa ed su aces compa ed o he ba e CP-Ti. C ea ed in h ps://BioRende .com.
D. San o e al.
Su ace & Coa ings Technology 512 (2025) 132277
21

No ably, he coa ings wi h ca bon concen a ions abo e 50 a . % dis-
played a hyd ophobic na u e, as e idenced by he high con ac angles,
and demons a ed imp o ed an ibac e ial p ope ies compa ed o bo h
uncoa ed 304 L s eel su aces and hose coa ed solely wi h Z . Bismu h
oxide coa ings also o e he ad an age o hyd ophobic su aces ha
emain unchanged e en unde sub-band gap i adia ion [224]. These
coa ings educe he abili y o mic oo ganisms o adhe e o he su ace,
making hem mo e e ec i e han con en ional i anium dioxide-based
pho oca aly ic coa ings. In con as , supe hyd ophilic coa ings o m a
dense hyd a ion laye wi h su ounding wa e molecules, c ea ing a
weak adhesion be ween bac e ia and he su ace [225,72]. This e ec-
i ely p e en s bac e ia om app oaching he implan su ace and in-
hibi s bac e ial adhesion. Fo ins ance, he e ec i e inhibi ion o
bac e ial p oli e a ion by amo phous SiC
x
N
y
O
z
coa ings on i anium
su aces was a ibu ed o he p esence o hyd ophilic unc ional g oups
[143]. These unc ional g oups c ea e an elec os a ic epulsion o ce
be ween he su ace and bac e ial cells, e ec i ely p e en ing hei
a achmen and g ow h. Addi ionally, su aces wi h highe oughness,
such as SiC
x
N
y
O
z
coa ings, exhibi s onge an imic obial ac i i ies
compa ed o smoo he su aces like i anium subs a es [143]. The
opog aphy, high hyd ophilici y, and low su ace nano oughness (<20
nm) o TiN coa ing, commonly u ilized in hip join p os heses,
con ibu e o i s e ec i eness in educing bac e ial adhesion [226]. In
e ms o mic o oughness, he an imic obial p ope ies o Ag coa ings
applied on mic og oo e su aces a e enhanced by he inc eased su ace
a ea, which p omo es he elease o Ag
+
ions and inhibi s bac e ial
g ow h. Howe e , a s udy conduc ed by Vladko a e al. e ealed ha he
an imic obial ac i i y o TiO
2
/SiO
2
/Ag coa ings is no signi ican ly
in luenced by su ace we abili y, su ace ene gy, and opog aphy [227].
Despi e he hyd ophilic na u e o hese coa ings, he inhibi ion o E. coli
g ow h is p ima ily de e mined by he p esence o he an imic obial
agen Ag and i s concen a ion ( anging om 9.66 o 19.75 a . %). In
addi ion o he ac o s men ioned ea lie , he mic os uc u e o he
coa ing also plays a signi ican ole in p e en ing bac e ial adhesion. A
s udy conduc ed on niobium-oxyni ide-coa ed su aces demons a ed
ha bac e ial adhesion was lowe compa ed o uncoa ed s ainless s eel,
likely due o di e ences in su ace ene gy and nano-s uc u al su ace
opog aphy [166]. The esul s u he indica ed ha c ys alline
NbOxNy-coa ed su aces exhibi ed educed bac e ial di usion
compa ed o amo phous and mixed amo phous-c ys alline NbOxNy-
coa ed su aces. The polymo phic o m o i anium dioxide, he s uc u e
and size o columna c ys als and c ys alli es o ming he coa ing a e
also highly signi ican . TiO2:Ag,N coa ings we e p oduced by spu e ing
a i anium a ge wi h sil e pins in an A /O
2
/N
2
a mosphe e, wi h he
low a io o he eac i e gases being a ied [64]. Inc easing he low
a io o ni ogen and oxygen esul ed in he o ma ion o an amo phous
ma ix. Howe e , h ough annealing a 500 ◦C o 1 h, he amo phous
ma ix ans o med in o e ined c ys alline phases, namely Ti
2.85
O
4
N,
ana ase, u ile, and sil e . This combina ion o phases con ibu es o
enhanced an ibac e ial p ope ies ha can be ac i a ed by isible ligh .
In addi ion o passi e de ensi e su aces, he e ha e been nume ous
e o s o de elop ac i e-a ack an ibac e ial su aces h ough he
applica ion o a wide ange o coa ings (Fig. 12). Like an ibio ics, an i-
mic obial nanoma e ials ac h ough one o mo e mechanisms o inhibi
mic obial g ow h o kill he in ading o ganisms. An ibio ic he apy
ypically esol es he symp oms caused by plank onic bac e ia eleased
om he bio ilm bu ails o e adica e he bio ilm i sel . Me al nano-
ma e ials a e s a egically ad an ageous as ac i e an ibac e ial agen s
because hei su ace a eas a e exceedingly la ge ela i e o hei size
and can easily pene a e he bio ilm [137]. Fo bac e ia cell memb anes,
me allic ma e ials can des oy he no mal s uc u e o p o eins (en-
zymes) on he memb ane. Fo example, Ag nanopa icles smalle han 6
nm can pene a e he en i e dep h o a bio ilm [228].
Se e al s udies ha e consis en ly demons a ed ha he main
bac e icidal e ec o sil e is achie ed h ough he elease o Ag
+
ions
ia an oxida i e eac ion in aqueous solu ions o biological mediums
Fig. 12. Schema ic illus a ion o passi e and ac i e an imic obial coa ings on bioma e ials. Passi e mechanisms inhibi bac e ial adhesion h ough an i-adhesion
e ec s acili a ed by p ope ies such as enhanced hyd ophobici y, hyd ophilici y, and nano oughness. Ac i e ac ion e adica es bac e ia h ough mechanisms such
as he con olled elease o an imic obial agen s. C ea ed in h ps://BioRende .com.
D. San o e al.
Su ace & Coa ings Technology 512 (2025) 132277
22
[229]. Ag
+
is known o in e ac wi h cell hiol g oups, binding o he
p ima y unc ional g oups ound in ce ain componen s such as en-
zymes. This in e ac ion p e en s bac e ial di ision, leads o damage o
he cell en elope and dis up he cell memb ane, esul ing in bac e i-
cidal e ec s. The induc ion o oxida i e s ess, caused by he p oduc ion
o ROS, including pe oxides, supe oxides, and hyd oxyl adicals induces
mi ochond ial damage [230,231].
Wojcieszak e al. showed ha he Ti
–
Ag and Ti
–
Au coa ings dis-
played a biocidal e ec , which can be a ibu ed o he di ec con ac
be ween hei su aces and mic oo ganisms [232]. On he o he hand,
he an imic obial ac i i y o he Ti
–
Cu ilm had bo h di ec and indi ec
cha ac e is ics, owing o he e icien ion mig a ion p ocess om he
ilm su ace o he su ounding en i onmen . Some coa ings a e also
capable o killing bac e ia by p oduc ion o eac i e oxygen species
(ROS). ROS p oduced by me allic nanoma e ials can di ec ly damage he
cons i uen s wi hin he bac e ia cy oplasm. Ti anium dioxide, a well-
known non oxic pho oca aly ic ma e ial ha can be inco po a ed in o
an ibac e ial pain s o coa ings o hospi al ouch-su aces, when
exposed o UV ligh unde goes pho oca aly ic p ocesses on i s su ace,
ac ing as an an imic obial agen [233]. When exci ed by ul a iole
ligh , TiO
2
nanopa icles gene a e ROS ha can des oy many o ganic
molecules and can e ec i ely kill a ious classes o mic oo ganisms. Fo
ins ance, in he case o pa hogenic P. ae uginosa, pho oca alysis ig-
ge ed by TiO
2
nanopa icles can cause he down egula ion o bac e ial
genes and p o eins associa ed wi h egula o y, signaling, and g ow h
unc ions. Simila ly, N-doped TiO
2
coa ed o hodon ic b acke s ha e
shown s ong an imic obial p ope ies agains S. mu ans o e a pe iod o
90 days, p e en ing enamel decalci ica ion du ing o hodon ic he apy
[234]. Addi ionally, Au and Ag nanopa icles we e success ully o med
on amo phous and c ys alline TiO
2
hin ilms by deposi ing a hin ilm o
sil e and gold and annealing i . The TiO
2
su ace wi h Ag nanopa icles
exhibi ed highe an ibac e ial e iciency and s onge an ibac e ial ac-
i i y agains Veillonella pa ula and Neisse ia sicca species compa ed o
Au nanos uc u ed i anium oxide su aces [235]. To u he enhance
pho oca alysis unde isible ligh and p o ide an imic obial unc ion
e en in da k en i onmen s, Fukumu a e al. p epa ed a Cu/SnO
2
nano-
bilaye coa ing using a magne on spu e ing me hod. The nano‑coppe
laye had a hickness o app oxima ely 7 nm, comple ely co e ing he
SnO
2
laye and esul ing in anspa en bilaye ilms [236]. Pos -
annealing was conduc ed a 400 ◦C in ai o 1 h o achie e a c ys al-
line SnO
2
phase and simul aneously oxidize he coppe laye o CuO. In
da k condi ions, CuO/SnO
2
exhibi ed he same e ec as he Cu-annealed
ilm (CuO). Howe e , unde ligh condi ions, CuO/SnO
2
demons a ed
a wo o de s o magni ude highe ac i i y due o he ad an ageous
pho oca aly ic p ope ies ob ained om he CuO/SnO
2
nanocomposi e
bilaye coa ings. When he CuO/SnO
2
nanocomposi e bilaye was
exposed o ligh , elec ons om SnO
2
we e exci ed and ans e ed o he
conduc ion band o CuO h ough in e acial cha ge ans e be ween
bo h laye s. As a esul , he an imic obial unc ion was enhanced by he
pho oca aly ic ac i i y unde indoo ligh exposu e compa ed o he
unc ion o CuO alone. In he same end, he an imic obial ac i i y o
[Ca
24
Al
28
O
64
]
4+
(4e
−
) (C12A7:e−) nanopa icles was ound o be highe
han ha o C12A7 nanopa icles, possibly due o he gene a ion o ROS,
such as O
2−
and OH [237]. This inding is consis en wi h he e ec o
ee elec ons and ee oxygen ions in a C12A7 cemen s uc u e on
an imic obial ac i i y [238]. Fu he mo e, he enhancemen o he
hos 's inna e immune esponses also leads o a a o able an ibac e ial
e ec [239]. Fo ins ance, an alum (Ta) can enhance he phagocy osis
o bac e ia by polymo phonuclea neu ophils (PMNs o neu ophils),
while simul aneously educing neu ophil lysis. Addi ionally, Ta nano-
ilms p omo e he elease o p oin lamma o y cy okines by mac o-
phages, u he con ibu ing o he enhancemen o local hos de enses.
In ecen yea s, signi ican e o s ha e been dedica ed o he
de elopmen o no el an imic obial coa ings, wi h a pa icula ocus on
me al and me al oxide-based coa ings such as sil e , coppe , zinc, and
o he me alloid compounds [137]. These coa ings ha e shown
p omising an imic obial p ope ies and will be u he discussed.
3.5.1. Sil e -based coa ings
Sil e has ga ne ed signi ican a en ion due o i s po en an ibac-
e ial ac i i y agains a b oad spec um o mic oo ganisms. Addi ionally,
sil e demons a es a low suscep ibili y o bac e ial esis ance and
possesses he abili y o inhibi polymic obial coloniza ion. Sil e and
sil e oxide nanopa icles ha e di e se an ibac e ial applica ions in
den is y, as sca olds o issue enginee ing and as wound healing ma-
e ials [240]. They ha e also been used as an imic obial ma e ials in
o he indus ies including d inking wa e disin ec ion [241] and ex ile
manu ac u ing [242]. As an example, Ag nanopa icles doped Ti
1.5
Z -
Ta
0.5
Nb
0.5
W
0.5
e ac o y high-en opy alloy (wi h a 9 a omic % Ag
con en ) deposi ed on a Ti6Al4V subs a e educed he colony o ming
uni o P. ae uginosa and S. au eus bac e ia by 98.5 % and 90.9 %,
espec i ely [243]. To enhance he an ibac e ial p ope ies and p omo e
bone o ma ion on he su ace o i anium implan s, Ag and Ta co-doped
amo phous calcium phospha e coa ing ilms we e ab ica ed by RF
magne on spu e ing [244]. The inco po a ion o bo h Ag and Ta ele-
men s ensu es a sus ained elease o Ag
+
ions, p o iding long-las ing
an ibac e ial e ec s. Howe e , he con inuous elease o sil e ions e-
sul s in a g adual inc ease o he elemen 's concen a ion wi hin he
adjacen media in con ac wi h he ilm. This p og ession ul ima ely
igge s oxic e ec s agains mammalian cells. To add ess his challenge,
do s o Ag/Zn gal anic couple we e s a egically deposi ed using
empla e-assis ed magne on spu e ing on co on nonwo ens and a poly
(
ε
-cap olac one)/gela in sca old [225]. These Ag/Zn gal anic couples
exhibi ed po en an ibac e ial ac i i y agains S. au eus and E. coli,
elying on he syne gis ic in e play o mic oscale elec ic ields, me al
ions, and eac i e oxygen species. Mo eo e , he Ag/Zn composi e
demons a ed good cy ocompa ibili y, c edi ed o i s minimal me al
coa ing a ea pe cen age (17.5 %). Ag and sil e ‑gold clus e s we e
success ully inco po a ed in o an amo phous ca bon ma ix and depos-
i ed on o polyu e hane subs a es commonly used in u e e al s en s
[245,86]. The p ima y goal o his s udy was o achie e an ibac e ial
ac i i y, as mic obial coloniza ion is a majo cause o ailu e in hese
biode ices. The an ibac e ial ac i i y o he coa ings was ound o be
di ec ly in luenced by he sil e ioniza ion mechanisms. ICP-OES anal-
ysis e ealed ha he elease o sil e ions is p ima ily dependen on he
amoun o sil e inco po a ed in o he a:C ma ix. In e es ingly, he
o ma ion o a bime allic alloy esul ed in a educed elease o sil e
ions. To enhance he an ibac e ial p ope ies o medical de ices, Ag and
AgO
x
hin ilms we e deposi ed using pulsed DC magne on spu e ing
[246]. Ou g oup success ully deposi ed Ag and AgO hin ilms on
lea he subs a es h ough dc eac i e magne on spu e ing [247]. The
AgO
x
-modi ied lea he s no only exhibi ed enhanced ic ional cha ac-
e is ics, bu also demons a ed ema kable an imic obial ac i i y
agains S. au eus and C. pa apsilosis. These indings sugges he po en ial
applica ion o AgOx-modi ied lea he s in he de elopmen o specialized
oo wea o indi iduals wi h diabe es. Mo eo e , by combining bio-
mime ic deposi ion wi h DC magne on spu e ing, we c ea ed mul i-
unc ionalized alumina sca olds coa ed wi h calcium phospha e (CaP)
and sil e -based hin ilms o enhance bioac i i y and an imic obial
p ope ies [87]. The s udy highligh s ha CaP-AgO coa ings exhibi ed
g ea e su ace oughness and a mo e hyd ophobic cha ac e compa ed
o CaP-Ag coa ings. Impo an ly, bo h ypes o coa ings showed an i-
mic obial ac i i y agains S. au eus, wi h he CaP-AgO coa ing demon-
s a ing supe io e icacy due o highe sil e ion elease du ing he
ini ial h ee days o imme sion. This ele a ed elease con ibu ed o
enhanced an imic obial p ope ies while main aining bioac i e pe o -
mance. Fu he mo e, in a s udy conduc ed by Tsendzughul e al., an
op ically anspa en mixed-phase sil e oxide hin ilm bioma e ial was
success ully p epa ed by adjus ing wo deposi ion pa ame e s: he ox-
ygen low a e and o wa d powe , du ing eac i e magne on spu e
deposi ion [248]. This esea ch highligh s he excep ional ligh ans-
mission capabili ies o sil e oxide ilms, sugges ing hei po en ial
D. San o e al.
Su ace & Coa ings Technology 512 (2025) 132277
23
applica ions beyond an imic obial su aces in hospi als. These ilms hold
p omise o a ious ields, such as con ac lenses and o he a eas whe e
bo h op ical anspa ency and an imic obial ac i i y a e c ucial.
3.5.2. Coppe and coppe oxide
Among he a ious ino ganic bac e icides o medicinal in e es , he e
is a g owing ocus on coppe and i s oxide due o i s low cos and
e ec i e an imic obial p ope ies [249,250]. The an ibac e ial ac i i y
o coppe me allic su aces is belie ed o occu h ough wo comple-
men a y mechanisms: he su ace- o-su ace in e ac ion be ween coppe
and bac e ia (con ac killing) and/o he su ace oxida ion o coppe ,
leading o he elease o an ibac e ial cup ic ions [251,73]. Kim e al.
u ilized he magne on spu e ing me hod o di ec ly deposi nano-
s uc u ed coppe (Cu) coa ings on Si-TiO
2
and glass-TiO
2
subs a es,
allowing o con ol o e he ma e ial p ope ies [236]. By adjus ing he
a ge powe densi y du ing deposi ion, he ilm p ope ies we e op i-
mized, esul ing in high c ys allini y deg ee, low su ace oughness,
minimum su ace ene gy, and low elec ical esis i i y. The an ibac e ial
ac i i y o S. au eus on he Cu ilms was analyzed and e ealed ha
physical con ac be ween he bac e ia and he Cu ilm induced acu e
memb ane damage, acili a ed by e ec i e elec on ans e om he
bac e ia memb ane o he highly conduc i e Cu ilm. Addi ionally, i
was obse ed ha ilms wi h lowe esis i i y demons a ed he mos
e ec i e an ibac e ial ac i i y. TaN/Cu nanocomposi e coa ings we e
p epa ed on a i anium modi ied SS alloy subs a e (D-9) using pulsed
magne on spu e ing [252]. The Cu con en in he coa ing was a ied in
he ange o 1 o 35 a . %. Among all, TaN/Cu wi h 10.5 a . % exhibi ed
he lowes ic ion coe icien . The TaN/Cu coa ings exhibi ed signi i-
can ly highe an ibac e ial ac i i y han Cu- ee TaN agains Pseudo-
monas ae uginosa. Wojciesza e al. conduc ed a s udy o in es iga e he
in luence o ma e ial composi ion on he s uc u e su ace p ope ies o
bioac i e coa ings based on Cu and Ti [253]. The bioac i i y o he
coa ings was ound o be associa ed wi h he ion mig a ion p ocess and
he oxida ion s a e o coppe ions, speci ically he amoun o Cu
+
ions
p esen . A nanoc ys alline coa ing wi h a lowe coppe con en (25 a .
%) exhibi ed nea ly nine imes mo e Cu
0
and Cu
+
ions compa ed o
Cu
2+
, which a e less bioac i e. Impo an ly, he amoun o coppe was
ound o ha e an impac on he iabili y o he L929 cell line. In a simila
s udy, Bada ae e al. demons a ed ha su ace-modi ied poly(lac ide-
co-glycolide) sca olds wi h a medium and high amoun o coppe
exhibi ed s ong an ibac e ial p ope ies, bu also showed oxici y o-
wa ds human gingi al ib oblas s [254].
3.5.3. Zinc oxide
Zinc oxide nanos uc u es a e known o hei b oad-spec um an i-
mic obial p ope ies [255,67]. In a s udy conduc ed by Widyas u i e al.,
zinc oxide hin ilms we e c ea ed using he he mal oxida ion me hod
on zinc hin ilms ini ially g own h ough HiPIMS [256]. The esea ch
indings highligh he c ucial ole o spu e ing powe in achie ing high
le els o pho oca aly ic pe o mance and an imic obial ac i i y. Spe-
ci ically, a spu e ing powe o 500 W, combined wi h he mal oxida-
ion, esul ed in he o ma ion o a well-s uc u ed ZnO c ys al phase
hin ilm wi h excellen compac ness and enhanced an imic obial ac-
i i y. The an imic obial e ec o ZnO hin ilms agains a ious pa h-
ogenic mic obes can be a ibu ed o mul iple ac o s. Fi s ly, he
in insic an imic obial p ope ies o Zn
2+
ions eleased by ZnO
con ibu e signi ican ly o i s an imic obial ac i i y. Addi ionally, he
elec os a ic in e ac ion be ween ZnO and he mic obe cell wall leads o
he des abiliza ion o mic obial memb anes. Finally, he o ma ion o
ROS h ough UV ligh adia ion u he enhances he an imic obial e -
ec o he ZnO hin ilms. To enhance he an imic obial p ope ies o
ZnO hin ilms, ca bon and coppe we e inco po a ed [257]. The addi-
ion o ca bon in ZnO hin ilms inc eases hei hyd ophobic cha ac e ,
mainly due o he p esence o C
–
C sp
3
hyb idized bonds. This in e-
g a ion o ca bon allowed o he c ea ion o me al- ee su aces wi h
compa able esul s o hose achie ed wi h coppe -doped hin ilms. In
he p esence o hese modi ied hin ilms, Pseudomonas ae uginosa
expe ienced a loss o i s cha ac e is ic shape, and leakage o in acellula
media occu ed. This can be a ibu ed o he p oduc ion and elease o
ROS, which p omo e he oxida ion o cellula s uc u es, he eby
al e ing he pe meabili y o he bac e ia and ul ima ely leading o hei
disin eg a ion. To enhance he os eoblas ic cy ocompa ibili y and an i-
bac e ial ac i i y o an alum-based su aces, ou g oup de eloped a
su ace modi ica ion s a egy in which Zn/ZnO nanopa icles we e
deposi ed on o TaCaP samples p epa ed by mic o-a c oxida ion (MAO)
using DC magne on spu e ing [39]. Addi ionally, a ca bon laye was
deposi ed o e he nanopa icles, esul ing in TaCaP-ZnC. This ca bon
coa ing imp o ed cell adhesion and p oli e a ion by p o iding a
smoo he and mo e cell- iendly mo phology. Fu he mo e, he ca bon
laye helped modula e he in e acial cellula in e ac ions wi h he Zn/
ZnO nanopa icles laye , educing he oxici y caused by di ec con ac
wi h Zn
2+
.
3.5.4. O he me al o me haloid-based coa ings
In o de o add ess conce ns ega ding en i onmen al impac and
oxici y associa ed wi h con en ional me al-based coa ings, signi ican
e o s ha e been dedica ed o he de elopmen o no el coa ings. An
example o hese coa ings is he inco po a ion o lan hanide elemen
sama ium (Sm) in o he s uc u e o hyd oxyapa i e using RFMS ech-
nique [258]. This app oach has been ound o signi ican ly enhance he
an imic obial ac i i y o he coa ing agains bac e ia such as E. coli and
S. au eus, as well as agains ungi like C. albicans. Ce ium, a a e ea h
elemen , has been ound o ha e he abili y o s imula e he me abolic
ac i i y o o ganisms and possess an ibac e ial p ope ies. Ce ium-doped
hyd oxyapa i e coa ings we e success ully gene a ed on i anium sub-
s a es using plasma-assis ed RFMS [259]. These coa ings exhibi ed a
biocidal e ec agains E. coli and C. albicans mic obial s ains a e 72 h
o incuba ion. In a s udy conduc ed by And onic e al., anspa en CeO
2
hin ilms we e deposi ed on glass subs a es using eac i e MS [260].
These CeO
2
ilms we e ound o e icien ly inhibi S aphylococcus au eus
bio ilms and plank onic g ow h, esul ing in a signi ican educ ion in
bac e ial cell coun s by 2 o 8 logs. Ge manium, a me alloid wi h
chemical simila i ies o Si, has shown po en ial o applica ions in op ics,
senso s, ca alysis, and e en as an an imic obial agen . In a ecen s udy,
he combina ion o ungs en and Ge in a W
–
Ge alloy was in es iga ed as
a composi ion ma e ial. The esul s demons a ed a signi ican educ ion
in he adhe ence o S aphylococcus au eus and Pseudomonas ae uginosa
compa ed o con ol g oups [261]. Bo on exhibi s high biological ac-
i i y and plays a signi ican ole in a ious physiological p ocesses,
namely in he o ma ion and unc ioning o bone issue and in he
egula ion o he immune esponse [262]. Mo eo e , s udies ha e p o-
ided e idence ha B ions can inhibi he o ma ion o highly adhesi e
bio ilms. I has been obse ed ha bo on supp esses he sel -
o ganiza ion o bac e ia, p e en ing he bio ilm om es ablishing i -
sel and adhe ing s ongly o su aces. Fo example, Ponoma e e al.
p epa ed B-doped TiCaPCON ilms wi h a ying B concen a ions (8, 11,
and 15 a . %) by MS echnique using wo composi e a ge s (TiC-CaO-
Ti
3
PO
x
and TiB
2
) in a gaseous mix u e o A +15 % N
2
[60]. To assess he
an ibac e ial cha ac e is ics o he B-doped TiCaPCON samples, hey
compa ed hem wi h wo-laye BO
x
/TiCaPCON–B and TiO
x
/
TiCaPCON–B ilms ob ained h ough h ee di e en me hods: (i) depo-
si ion o a B
2
O
3
op laye , (ii) annealing, and (iii) elec ochemical
oxida ion o he as-deposi ed B-doped ilms. The esul s demons a ed
ha only he sample wi h a B
2
O
3
op laye was able o comple ely
inac i a e E. coli cells and p e en bio ilm o ma ion. No ably, he su -
ace o he wo-laye B
2
O
3
/TiCaPCON–11 % B ilm exhibi ed simul a-
neous bac e icidal p ope ies agains E. coli s ains while emaining non-
oxic o os eoblas ic cells. Mo eo e , he bio ilm inhibi o y p ope y o
coa ings con aining bo on can also be a ibu ed o he impac o su ace
oughness on su ace opog aphy and i s e ec on bio ilm o ma ion.
The nanome ic ange o he su ace opog aphic ea u es o bo on
ca bon ni ide (BCN) is much smalle han he size o mic obial cells,
D. San o e al.
Su ace & Coa ings Technology 512 (2025) 132277
24
esul ing in a subs an ial dec ease in he con ac a ea be ween he
bac e ial cells and he nanocoa ed su ace [263]. This educed con ac
a ea may in luence he ac i a ion o bac e ial adhesion genes and genes
in ol ed in he sec e ion o ex acellula ma ix, consequen ly a ec ing
cell a achmen and subsequen bio ilm o ma ion on BCN. These ind-
ings highligh he po en ial o bo on in comba ing bac e ial in ec ions.
Fu he esea ch in his a ea may p o ide aluable insigh s in o he
mechanisms unde lying bo on's an imic obial p ope ies and i s po en-
ial applica ions in biomedical ield.
Mo eo e , in ecen yea s, he e has been g owing in e es in mul i-
elemen hin ilms as a p omising ca ego y o nano-enginee ed su aces.
Among hese, Z -based ilms (such as Z
–
Cu, Z -Cu-Ag, Z CN, Z /Z CN
mul ilaye ) [59], as well as Ti-based ilms (including TiN, TiCu, Ti-Z -
Si), ha e demons a ed ema kable p ope ies, namely a supe io com-
bina ion o high mechanical s eng h, biocompa ibili y, and an ibac e-
ial ac i i y [264]. Addi ionally, he desi ed combina ion o mechanical
s eng h, biocompa ibili y, and an imic obial ac i i y can be achie ed
h ough he cons uc ion o mul i-laye s [63,64]. No ably, s udies ha e
e ealed he po en ial an ibac e ial beha io achie ed by inco po a ing
Au, Cu, Zn, and Ag in o Ti-based ilms. In a s udy conduc ed by Mina-
Aponza e al., Ti/Ag ilms we e ab ica ed using a ious con igu a-
ions (monolaye and mul ilaye ) ia magne on spu e ing. The an i-
mic obial ac i i y o hese ilms was assessed agains Pseudomonas
ae uginosa and Bacillus sub ilis bac e ia, as well as Candida k usei and
Candida albicans yeas s [265]. The indings indica ed ha he mul ilaye
coa ing exhibi ed enhanced TiO
2
laye o ma ion, esul ing in excellen
co osion p o ec ion. Fu he mo e, i demons a ed s onge inhibi ion
o colony- o ming uni s (CFUs) when es ed agains C. k usei and
C. albicans ungi. Howe e , i is impo an o no e ha SEM mic og aphs
o he ilm e ealed he de achmen o laye s on he su ace. This
de achmen p esen s a po en ial isk o he longe i y o biomedical de-
ices when implan ed wi hin a hos o ganism. As p e iously discussed,
nume ous coa ings ha e been de eloped o p e en bac e ial in ec ions
in implan s by eleasing an ibac e ial ions. Howe e , p ecise con ol
o e ion elease o e ec i ely elimina e bac e ia wi hou ha ming cells
emains a challenge. To add ess his, Tan e al. p opose an inno a i e
app oach: augmen ing su ace local alkalini y wi h a MgO ilm o
dis up bac e ial espi a ion [266]. Biodeg adable MgO ilms o a ying
hicknesses we e me iculously ab ica ed on i anium using RFMS. As
he ilm hickness inc eased, excep ional an ibac e ial e icacy agains
bo h E. coli and S. au eus was obse ed. The local alkaline mic oen i-
onmen on he MgO ilm su ace in e e es wi h bac e ial espi a ion by
a enua ing he ansmemb ane p o on concen a ion g adien , he eby
obs uc ing ene gy me abolism and inducing oxida i e s ess in bac e ia.
Fu he mo e, he MgO ilm exhibi ed a ema kable abili y o selec i ely
comba bac e ial g ow h e en in he simul aneous p esence o bac e ia
and os eoblas cells. This dual unc ionali y posi ions he MgO ilm as a
p omising candida e o enhancing implan sa e y and e icacy.
In summa y, PVD coa ings o e an e ec i e s a egy o p e en
bac e ial adhesion and bio ilm o ma ion on medical de ices h ough
bo h passi e and ac i e mechanisms. Passi e app oaches al e su ace
oughness, chemis y, o we abili y o de e mic obial a achmen ,
while ac i e coa ings inco po a e an imic obial agen s such as sil e ,
coppe , zinc, and magnesium o elimina e bac e ia. Mul ilaye and
doped ilms (e.g., Ti
–
Ag, Z -Cu-Ag, MgO, ZnO) p oduced ia magne on
spu e ing ha e shown s ong an ibac e ial e ec s and selec i e cy o-
compa ibili y. Eme ging inno a ions include sma su aces wi h
con olled ion elease, localized alkalini y, o ligh esponsi eness,
u he enhancing an imic obial e icacy and ensu ing long- e m de ice
sa e y.
4. Challenges o PVD coa ing o biomedical implan s
Recen li e a u e highligh s he signi ican po en ial o PVD—pa -
icula ly magne on spu e ing—as a su ace enginee ing echnique o
biomedical de ices. I s p o en abili y o deposi hin, adhe en , and
unc ional coa ings has led o an inc easing adop ion in comme cial
applica ions. Fo example, Ionbond o e s o hopaedic implan s—such
as spinal discs, pedicle sc ews, and guide ods—coa ed wi h TiN o C N,
which signi ican ly enhance wea esis ance and educe ion elease,
he eby imp o ing mechanical s abili y and biocompa ibili y [267].
Ad anced coa ings like AlTiN and TiAlN, p o ided by companies such as
S a A c and Ionbond, a e applied o su gical ins umen s o educe ligh
e lec ion du ing minimally in asi e p ocedu es, endu e agg essi e
s e iliza ion cycles, and p ese e cu ing pe o mance. Addi ionally,
composi e coa ings such as an alum (Ta) and i anium‑s on ium-oxide
(Ti-S -O), deposi ed ia magne on spu e ing, ha e demons a ed
excellen osseoin eg a ion and bone ancho age in den al and o ho-
paedic implan s [268,269]. Clinical ou comes om hese applica ions
epo ex ended implan longe i y, ein o cing he clinical ele ance o
spu e ed coa ings and suppo ing hei con inued ansla ion om
labo a o y esea ch o p ac ical heal hca e solu ions [268,269]. Despi e
hese ad an ages, magne on spu e ing p esen s no able challenges in
biomedical applica ions. A key limi a ion is i s line-o -sigh deposi ion,
which hinde s uni o m coa ing on complex o ecessed geome ies,
po en ially esul ing in inconsis en hickness, subop imal adhesion, and
comp omised unc ionali y [270]. Addi ionally, he high- acuum en i-
onmen equi ed o deposi ion en ails signi ican equipmen and
main enance cos s, which can hinde scalabili y. Residual s esses
induced du ing spu e ing may also a ec coa ing adhesion and me-
chanical in eg i y, issues pa icula ly ele an o load-bea ing implan s.
O he conce ns include elemen al inhomogenei y and pinhole de ec s,
which can unde mine he coa ing's ba ie p ope ies and lead o
localized co osion o ea ly de ice ailu e. To add ess hese limi a ions,
ad ancemen s in bo h equipmen and p ocessing echniques a e being
explo ed. App oaches such as subs a e o a ion, il ing, biasing, and
ad anced me hods like HiPIMS o hollow ca hode spu e ing ha e been
de eloped o enhance coa ing uni o mi y and plasma ioniza ion
[271,272]. Mo eo e , inno a ions in chambe design and hyb id depo-
si ion sys ems—combining PVD wi h non-line-o -sigh echniques—a e
unde in es iga ion o ensu e uni o m coa ing co e age on in ica e
geome ies. Con inued esea ch in p ocess op imiza ion, ma e ials
de elopmen , and su ace enginee ing is essen ial o ully ealize he
po en ial o PVD echnologies in he nex gene a ion o biomedical
implan s.
5. Fu u e di ec ions
While he sho - e m bene i s o PVD coa ings—such as enhanced
biocompa ibili y, co osion esis ance, and mechanical pe o m-
ance—a e well documen ed, hei long- e m clinical eliabili y emains
an impo an challenge. In i o, biomedical implan s a e subjec ed o
dynamic physiological condi ions, including luc ua ing pH, enzyma ic
ac i i y, mechanical a igue, and complex hos esponses. These ac o s
can comp omise he long- e m in eg i y and unc ionali y o coa ings,
emphasizing he need o comp ehensi e du abili y assessmen s.
Al hough magne on-spu e ed coa ings a e ecognized o hei dense,
adhe en , and s able cha ac e is ics, longi udinal clinical da a emain
limi ed. Fu u e esea ch should he e o e p io i ize accele a ed aging
p o ocols and in i o/in i o e alua ions ha closely mimic ealis ic
biological en i onmen s. Moni o ing ion elease, adhesion unde
cyclical mechanical s ess, and e olu ion o su ace mo phology and
bioac i i y will be key o ensu ing bo h sa e y and sus ained pe o -
mance in clinical use. In pa allel, he inco po a ion o machine lea ning
and AI-d i en p ocess op imiza ion can accele a e ma e ial design,
enabling he de elopmen o cus omized, adap i e coa ings. Fu u e in-
no a ions should also explo e he in eg a ion o bioac i e agen s (e.g.,
g ow h ac o s o an imic obial pep ides), he c ea ion o s imuli-
esponsi e sma su aces, and he ab ica ion o g adien o mul i-
unc ional coa ings ha simul aneously p omo e biocompa ibili y,
osseoin eg a ion, and an imic obial p o ec ion. Finally, he ansi ion
om labo a o y esea ch o clinical applica ion will equi e
D. San o e al.
Su ace & Coa ings Technology 512 (2025) 132277
25
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