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Colloidal s abili y
o phy osyn hesised gold
nanopa icles and hei ca aly ic
e ec s o ne e agen deg ada ion
Ve onika Holišo á1*, Ma in U ban2, Zuzana Kon ičko á1,3, Ma ek Kolenčík1,4,
Pa el Mančík1, Jiří Slabo inský2, Gab iela K a ošo á1 & Daniela Plachá1,3*
He ein, Tilia sp. b ac leacha e was used as he educing agen o Au nanopa icles (Au NPs)
phy osyn hesis. The colloidal p ope ies o he p epa ed Au NPs we e de e mined o con i m
hei s abili y o e ime, and he NPs we e hen used as ac i e ca alys s in soman ne e agen
deg ada ion. The Au NPs cha ac e isa ion, ep oducibili y and s abili y s udies we e pe o med unde
ansmission elec on mic oscopy, ul a iole isible spec oscopy and wi h ζ-po en ial measu emen s.
The eac ion kine ics was de ec ed by gas ch oma og aphy coupled wi h mass spec ome y de ec o
and solid-phase mic o-ex ac ion o con i m he Au NPs applicabili y in soman hyd olysis. The
‘g een’ phy osyn he ic o ma ion o colloidal c ys alline Au NPs wi h dominan quasi-sphe ical shape
and 55 ± 10 nm diame e was success ully achie ed, and he e we e no signi ican di e ences in
mo phology, ζ-po en ial o abso bance alues obse ed du ing he 5-week pe iod. This e i ied he
p epa ed colloids’ long- e m s abili y. The soman ne e agen was deg aded o non- oxic subs ances
wi hin 24 h, wi h 0.2156 h−1 eac ion a e cons an . These esul s con i med bio-nano echnology’s
g ea po en ial in p epa a ion o s able and unc ional nanoca alys s o deg ada ion o haza dous
subs ances, including chemical wa a e agen s.
Chemical wa a e agen (CWA) decon amina ion has a e y high p io i y in mili a y de ence and especially in
he cu en igh agains e o ism. The Soman (O-Pinacolyl me hyl-phosphono luo ida e) examined in his
a icle is a CWA wi h ex eme oxici y o bio a. This o ganophospha e is a ne e agen (NA) which comp omises
he no mal ne ous sys em unc ioning by inhibi ing ace ylcholines e ase ca aly ic b eakdown o ace ylcholine
and o he choline es e neu o ansmi e s1,2. Soman causes dea h wi hin a ew minu es o a ew hou s a e
exposu e, dependen on he dose and ou e o exposu e, bu i can be deg aded by hyd oly ic clea age o i s P–F
bonding1. Some oxicology s udies show ha pinacolylme hylphosphonic acid (PMPA) is o med as an in e -
media e subs a e and ha he me hylphosphonic acid (MPA) usually o med as a inal deg ada ion p oduc o
soman hyd olysis is conside ed non- oxic2.Se e al s udies ha e also ocused on he deg ada ion o CWAs and
hei simulan s using di e en kinds o NPs. The Fe, Zn and Al me al nano-dispe sed oxides o oxo-hyd oxides
ha e been p epa ed by homogeneous hyd olysis o sulpha es, ni a es and chlo ides and es ed o hei abili y
o con e ne e-agen s o non- oxic p oduc s a 25°C3.
Chemical p epa a ion o Au NPs suppo ed on mesopo ous TiO2 achie ed e ec i e soman pho oca aly ic
decon amina ion4. The nanocomposi e was p epa ed by biosyn hesis using he Mallomonas kalinae b own algae
wi h SiO2 on i s su ace5, and soman deg ada ion was con i med by he nanogold embedded on his su ace.
Nanogold is a well-known ca aly ic nanoma e ial, and Au NPs exhibi he he modynamic s abili y, ine ness,
elec ic and op ic conduc i i y applicable in a wide a ie y o ca alysis. Au NP’s ca alysis is gene ally possible
because o hei la ge a ea and dec easing pa icle size dis ibu ion6–8, and he ca aly ic e ec is signi ican ly
enhanced a highe nanogold c ys allini y, by ce ain mo phology ypes and unco e ed g ain bounda ies. In
addi ion, collec i e oscilla ion o conduc i e elec ons be ween he dielec ic and me al–su ace plasmon eso-
nance (SPR) occu s unde an ex e nal op ical ield6,7, and he combina ion o hese cha ac e is ics can lead o
OPEN
1Nano echnology Cen e, CEET, VŠB – Technical Uni e si y o Os a a, 17. lis opadu 2172/15, 708 00 Os a a,
Czech Republic. 2Na ional Ins i u e o Nuclea , Biological and Chemical P o ec ion, . .i., Kamenná 71, 262
31 Milín, Czech Republic. 3ENET Cen e, CEET, VŠB – Technical Uni e si y o Os a a, 17. lis opadu 2172/15, 708
00 Os a a, Czech Republic. 4Depa men o Soil Science and Geology, Slo ak Uni e si y o Ag icul u e in Ni a,
T . A. Hlinku 2, 949 76 Ni a, Slo ak Republic. *email: [email p o ec ed]; [email p o ec ed]
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he dis up ion o ac i e bonds and g oups o a oms in he o ganophospha e molecule9. Mos impo an ly, Au
NPs ha e no disce nible oxic e ec s on li ing o ganisms10.
NPs can be p epa ed by biosyn hesis as well as chemical and physical me hods, and his p o ides an ecologi-
cal app oach o bo om-up syn hesis11 whe e ino ganic co es wi h unc ional o ganic packaging a e o med.
Rela i ely long- e m s abili y and a iabili y o e a wide applica ion ange ha e ecen ly p o ed su p ising11,
and Au NP biosyn hesis has been con i med in bac e ia12, cyanobac e ia13, algae8, mic oscopic ungi14 and di -
e en plan ex ac s15–17. The cu en use o plan s o plan pa s leacha es and/o ex ac s o NPs biosyn hesis
is simple and a ac i e. This phy osyn he ic me hod uses soluble plan subs ances such as alkaloids o simple
phenolic compounds which possess bo h educ ion and s abilisa ion e ec s17,18.
NPs s abili y is one o he mos impo an p ope ies in nanoma e ial applica ion15,16,19, and his is based on:
(i) NP size, su ace o olume a io, c ys allini y and mo phology20; (ii) NP exposed su ace cha ged wi h speci ic
ions and an elec ic double-laye s uc u e wi h speci ic capaci y21 and (iii) he ionic s eng h and pH, and o he
c i ical ac o s including empe a u e21.
Nanogold’s ema kable p ope ies make i one o he mos ca aly ically ac i e elemen s. S able biosyn hesised
sphe ical Au NPs ancho ed on a silica su ace ha e been employed in CO con e sion8, and phy osyn hesised
nanogold was used o ni ophenol and o ganic dye deg ada ion in he p esence o NaBH411,19. These e ec s
inspi ed us o conduc he Au NPs phy osyn hesis wi h Tilia sp. linden b ac aqueous leacha e in o de o e i y
he NPs s abili y and expe imen ep oducibili y. Finally, he Au NPs we e used o soman deg ada ion wi h
subsequen e alua ion by gas ch oma og aphy coupled wi h mass spec ome y and solid-phase mic o-ex ac ion.
Resul s and discussion
UV–VIS measu emen . Suspension colou change om yellow o da k pu ple was obse ed a e mix-
ing he Au p ecu so and plan leacha e o 15min (Fig.1). The nanogold ba ch phy osyn hesis in all Au1-Au5
samples indica es he linden b ac s leacha e educing po en ial, whe e he Au(III) ions a e educed o Au0 by
phy ochemicals p esen in he leacha e11. S udies sugges ha biomolecules such as p o eins, enzymes and la-
onoids can educe Au(III) ions du ing phy osyn hesis o o m Au NPs and s abilise hem di ec ly in a one-s ep
p ocess22,23.
The Au samples’ abso p ion spec a we e measu ed in he 490 o 600nm ange and he cha ac e is ic abso p-
ion peaks we e egula ly de e mined o e 5weeks. The linden leacha e and Au p ecu so mix u es exhibi ed one
abso bance peak a 540–548nm in he Au1-Au5 samples. This iden i ied he Au NPs’ SPR phenomenon24. Fig-
u e2 depic s he Au1 sample which was selec ed o soman deg ada ion es ing as a ep esen a i e o all analyses.
NPs UV–VIS abso p ion is mainly in luenced by size, shape, concen a ion, agglome a ion capaci y and he
e ac i e index o he NP su ace20,25. I NPs des abilise o e ime, he o iginal abso p ion peak will dec ease
in in ensi y due o deple ion o s able NPs. The peak is hen b oadened, o a seconda y peak is o med a longe
wa eleng h because o he o ma ion o agg ega es o agglome a es. Thei o ma ion also leads o changes in
band posi ion o e olu ion o a new SPR peak a highe wa eleng h20.
The e was no change in he abso p ion maxima wa eleng h (λmax) obse ed o he Au1 sample a 540nm
o e he 5-week expe imen (Fig.2). In ensi y did no change signi ican ly du ing measu emen , and no NP
agg ega ion occu ed in his pe iod. Figu e2 also enables he p edic ion ha he colloid con ains NPs wi h a
wide dis ibu ion o pa icle size and shape20,25. Table1 p esen s he a i hme ic mean and s anda d de ia ion o
abso p ion in ensi y (A) and abso bance maxima (λmax) o he i e Au NPs p epa a ion epe i ions.
The UV–VIS spec oscopy gene ally con i med mino changes in abso bance and abso p ion maxima o he
Au1-Au5 samples du ing he expe imen al pe iod (Table1) and he Au NPs in he colloid dispe sion we e s able.
Mo eo e , no signi ican agg ega ion was obse ed in any p epa ed colloid and no isible colloid colou change
occu ed du ing s o age. These esul s a e u he s eng hened by he ζ-po en ial measu emen s.
Figu e1. Ba ch phy osyn hesis o Au NPs using linden b ac s leacha e.
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Size and mo phology o phy osyn hesised Au NPs. The size, mo phology, and c ys al s uc u e o
syn he ised Au NPs we e cha ac e ised by TEM. Figu e3 shows hei a ied shape in he illus a ed Au1 sample
which has quasi-sphe ical and iangula nanopla es and hexagonal Au NPs. The Au1 sample size o quasi-
sphe ical NPs was 51 ± 11nm, and 184 ± 46nm o iangula and hexagonal nanopla es. No signi ican changes
in NP size we e obse ed in hese pa ame e s wi hin 5weeks; wi h 46 ± 14nm and 180 ± 50nm obse ed in he
5 h week. The e was also a mo e s abilised and less con as ing phy ochemical coa ing a ound he NPs.
S a is ical analysis o he Au1-5 samples es ablished ha he dominan NP shape was quasi-sphe ical wi h
a e age 55 ± 10nm size, and he iangula and hexagonal-shaped Au NPs’ size dis ibu ion was 199 ± 55nm.
The mean quasi-sphe ical and non-sphe ical NP sizes we e e alua ed 5weeks a e ini ial obse a ion, wi h he
ollowing esul s; quasi-sphe ical NPs measu ed 55 ± 12nm and non-sphe ical NPs 194 ± 54nm.
P e ious UV–VIS spec a p o ided no e idence o di e en abso p ion peaks o smalle and la ge Au NPs.
This may ha e been due o he highe concen a ion o Au NPs wi h size a ound 60nm which co esponds o
abso p ion maxima o app oxima ely 540 nm26. Howe e , TEM cha ac e isa ion con i med he p esence o NPs
c ys alline s uc u e wi h b oade pa icle size and shape dis ibu ion.
While ou phy osyn he ic me hod has es ablished ep oducible esul s, mino di e ences a e no iceable in
he obse ed samples. This is mos likely due o he amoun and con en o phy ochemicals in he applied plan
biomass. Howe e , u he imposed condi ions, such as he sou ce o bio- educ an s and bio-s abilise s, he ype
o me al p ecu so and i s concen a ion and he con ac ime be ween biomass and p ecu so may enhance he
ep oducibili y o Au NPs p oduc ion wi h g een syn hesis emphasis.
In addi ion, he o ma ion o Au NPs wi h di e en sizes and shapes he ein was mos likely associa ed wi h
he wide ange o biomolecules in linden b ac leacha e such as gallic acid, ca echin and que ce in27,28. Fo exam-
ple, he que ce in p esence could be esponsible o o ma ion o sphe ical Au NPs in he size ange om 20 o
45nm16. Choi e al. and Ga ade e al. also desc ibed he biosyn hesis and s abilisa ion o sphe ical nanopa icles
and iangula and hexagonal Au NPs wi h he size ange om 17 o 80nm media ed by ca echin and gallic
acid22,29. In addi ion, he linden b ac s in ou expe imen s con ain he p e iously men ioned phy ochemicals
which a e app o ed as sui able biomass o Au NP educ ion and s abilisa ion30,31.
ζ-po en ial measu emen . The ζ-po en ial deno es a double-laye elec os a ic su ace po en ial which is
highly dependen on he immedia e en i onmen , and i s alue adequa ely de e mines NPs s abili y. The con en-
ional heo e ical bounda y be ween NP s abili y and ins abili y lies be ween − 30 and + 30mV; and lowe and
highe alues han hese bounda ies es ablish colloidal s abili y s a us21. Table2 he ein highligh s he es ablished
mode a ely s able Au1 colloidal pH and ζ-po en ial alues.
Figu e2. UV–VIS spec a o Au1 sample measu ed o e 5weeks.
Table 1. The a i hme ic mean and s anda d de ia ion o abso p ion in ensi y (A) and abso bance maxima λmax
Au colloids p epa ed in pa allel.
Week A λmax [nm]
11.63 ± 0.15 543.40 ± 3.13
21.60 ± 0.12 543.20 ± 3.27
31.57 ± 0.16 542.40 ± 3.29
41.70 ± 0.10 542.40 ± 3.21
51.66 ± 0.11 543.20 ± 3.27
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The ζ-po en ial was egula ly measu ed o all samples, and Fig.4 shows he sligh al e a ion in ζ-po en ial
a i hme ic mean o e he expe imen al pe iod. The phy osyn hesised Au NPs we e classi ied as mode a ely
s able because he measu ed alues did no each he es ima ed s abili y bounda y. The nega i e ζ-po en ial
alues we e de ec ed he e because he capping agen s comp ised ac i e bioo ganic compounds wi h long- e m
change e ec s32. We hen conside ed he s abilisa ion p ocess comple e because no signi ican change was no ed
in ζ-po en ial alue.
The Au NPs samples’ pH alue was con inuously moni o ed because he ζ-po en ial alue undamen ally
depends on pH and empe a u e change. Figu e5 he ein shows ha he pH o all Au NPs samples was cons an
h oughou he expe imen al pe iod a app oxima ely pH 2 a cons an labo a o y empe a u e.
Soman deg ada ion. Hyd oly ic deg ada ion o soman was pe o med in he p esence o h ee ma e ials:
(i) pu e linden b ac s leacha e (C1); (ii) HAuCl4 Au p ecu so and (iii) colloidal Au NPs (Au1).
Figu e3. TEM analysis e eals phy osyn hesised Au1 NPs shape and size he e ogenei y. C ys alline Au NPs
we e con i med by SAED. (A) The majo i y a e quasi-sphe ical wi h some p esence o iangula (B) and
hexagonal (C) pa icles e iden . Au NPs we e de ec ed bo h isola ed and in g oups (D).
Table 2. ζ-po en ial and pH alues o Au1 samples o e he i e-week expe imen al pe iod.
Week ζ –po en ial [mV] pH
1− 24.1 ± 0.5 2.19
2− 21.9 ± 1.7 2.15
3− 20.8 ± 0.6 1.77
4− 20.2 ± 1.4 2.03
5− 19.9 ± 1.4 2.01
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Figu e6 shows he hyd olysis cou se ca alysed by colloidal Au NPs wi h 2.5mmol.dm−3 Au compa ed o
soman deg ada ion wi h Au p ecu so con aining he same Au concen a ion and he Cl con ol sample. The Au
NPs achie ed 99.38% soman con e sion in 24h wi h 0.2156h−1 deg ada ion a e cons an , and he phy osyn he-
sised Au NPs can in luence soman hyd olysis h ough he quan um-size e ec s gene a ed by elec ons con ined
in a small olume. The li e a u e s a es ha a basic en i onmen o pH 8–14 shi s he eac ion equilib ium o
deg ada ion p oduc s. Howe e , he Au NP ca aly ic e ec has been con i med in he pH 2.2 acidic en i onmen ,
and his is much be e han li e a u e epo s o hyd olysis p oceeding a neu al pH5.
The esul an con e sion o soman in he p esence o he pH 4 Au p ecu so was 97.77% a e 24h wi h
a endan eac ion a e cons an o 0.1614h−1. The di e ing Au(I) and Au(III)) oxida ion s a es pa icipa e as
ca alys s in o ganic syn hesis. Fo example, he HAuCl4 Au p ecu so used as a ca alys deg aded soman due o
i s oxida ion po en ial33.
Al hough hepH 5.1 linden leacha e exhibi ed no deg ada ion e ec on he soman ne e agen and he phy-
ochemicals in he wa e ex ac did no in luence soman decomposi ion, soman con e sion by linden leacha e
p oceeded in a simila manne o he simple soman hyd olysis5.
The deg ada ion p oduc s we e de e mined by SPME and GC/MS sc eening analysis. The amoun o MPA
s anda d solu ion, as he inal deg ada ion p oduc , was 100ng, and Table3 highligh s iden i ica ion o he ol-
lowing compounds by mass spec a: e hylace a e (E -Ac, CAS: 141-78-6), pinacolylalcohol (P-ol, CAS: 464-07-3),
dipinacolylme hyl phosphona e (DPMP, CAS: 7040-58-6), soman (CAS: 96-64-0).
The ollowing we e also p esen in he mass spec um (1) Si-pinacolylme hylphosphonic acid PMPA— he Si
de i a i e o med a e hyd olysis o he P-F bond and (2) Si-me hyl phosphonic acid MPA— he Si de i a i e
o med a e hyd olysis o he P-F and P-O bonds. Figu e7 shows ha PMPA was he p oduc mos o med in
he i s s age o he samples’ soman hyd olysis, and Table4 depic s ha MPA was de ec ed as a inal non- oxic
deg ada ion p oduc 34,35.
Soman hyd olysis was ca alysed mo e e ec i ely wi h Au NPs han wi h HAuCl4 Au(III) ions. The soman
deg ada ion mechanism was mos likely di e en in he p esence o Au(III) ions o he Au NPs ac ion. We
Figu e4. A i hme ic mean and s anda d de ia ion o ζ-po en ial alues o he measu ed samples, including
Au1.
Figu e5. A i hme ic mean and s anda d de ia ion o pH alues o measu ed samples including Au1.

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Figu e6. Kine ic deg ada ion o soman hyd olysis in he p esence o linden leacha e, gold p ecu so and Au
NPs.
Table 3. SPME moni o ing o hyd olysis p oduc s a e 24h.
Samples
Moni o ed analy es (Peak a ea)
E -Ac P-ol DPMP Soman
Linden leacha e – 688, 457 1,345,668 38,689,503
HAuCl4 (2.5mmol·dm−3) 847,594 1,719,116 5,953,960 1,297,049
Au NPs (2.5mmol·dm−3) – 1,995,211 1,043,776 336,166
Figu e7. Hyd olysis o soman34,35.
Table 4. P oduc s o soman deg ada ion a e 24h de ec ed by GC/MS sc eening analyses.
Samples
Moni o ed analy es (Peak a ea)
Soman PMPA-Si MPA-Si
S anda d solu ion o soman (100ng) 11,391,354 – –
S anda d solu ion o MPA-Si (100ng) – – 44,622,216
Linden leacha e 35,872,335 738,678 745,057
HAuCl4 (2.5mmol·dm−3) – 1,874,961 134,487
Au NPs (2.5mmol·dm−3) – 23,369,827 501,546
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obse ed ha e hyl ace a e and he highes concen a ion o DPMP we e de ec ed in he sample only when
HAuCl4 was p esen , because he PMPA-OH g oup was hen p e e en ially es e i ied o o m DPMP. The e o e,
he concen a ion o he low-molecula PMPA and MPA inal p oduc s in he Au NPs’ sample was 12.5 and 3.7
imes highe , espec i ely, han in he eac ion whe e HAuCl4 was mixed wi h soman.
Finally, al hough samples wi h nanogold had lowe pH alue, he Au NPs p o ided be e ca aly ic ac i i y o
soman hyd olysis han HAuCl4 a e 24h. In addi ion, oxicology s udies eco d ha pinacolylme hylphosphonic
acid is o med as an in e media e and me hylphosphonic acid is usually o med as a inal deg ada ion p oduc
o soman hyd olysis and is conside ed non- oxic2.
Me hods
Au nanopa icle phy osyn hesis. Tilia sp. b ac s we e collec ed in he No á Ves a ea o F ýdlan nad
Os a icí in The Czech Republic. He e, 2g o he d ied biomass and 50mL o 80°C Milli-Q wa e we e mixed
o 15min a s a ic condi ion. The leacha e was il e ed h ough a 0.22µm sy inge il e (MCE, Millex-GS, Me ck
Millipo e, Ge many) and 5mmol·dm−3 aqueous solu ion o HAuCl4 (Sigma-Ald ich, USA) was used as ini ial
p ecu so o AuNP gene a ion. The leacha e and p ecu so we e mixed in 1:1 / a io o 15min and he inal
colloid was main ained in he da k a 5°C.
The Au NPs and linden b ac s leacha es p epa a ions we e epea ed i e imes o con ol phy osyn he ic
ep oducibili y. The inal AuNP samples we e deno ed Au1, Au2, Au3, Au4 and Au5, and he C1, C2, C3, C4 and
C5 linden b ac s leacha es o each sample we e s o ed as con ols. Finally, he colloidal solu ions we e b ough
o 25°C o subsequen expe imen s and measu emen s.
Physical–chemical p ope ies o colloidal Au nanopa icles. S udy o Au colloidal s abili y and phy-
osyn he ic ep oducibili y. Au NP s abili y and phy osyn hesis ep oducibili y we e s udied by egula ly meas-
u ing UV–VIS abso p ion maxima, ζ-po en ial and colloid pH alues each week o 5weeks o all Au1-Au5
samples. The cha ac e is ic Au NPs abso p ion peaks we e measu ed by UV–VIS spec opho ome e (LAMBDA
11, Pe kin Elme Ins umen s, USA) wi h 0.5nm uni s ep in he 450-600nm wa eleng h ange. The ζ-po en ial
was pe iodically con olled by Ze aSize Nano–ZS (ZEN 3600; Mal e n Ins umen s L d., UK), and solu ions
we e e alua ed on sys em acid–base equilib ium by measu ing pH alues by EUTECH pH 5 + me e (Eu ech
Ins umen s, USA).
NPs size dis ibu ion, mo phology and c ys al s uc u e de e mina ion. NP mo phology and size dis ibu ion
we e cha ac e ised by ansmission elec on mic oscopy (TEM) a 80kV using JEOL 1200 EX (JEOL, Japan),
and he c ys al s uc u e was moni o ed by selec ed a ea elec on di ac ion (SAED). The 2μL liquid sample was
placed on a coppe g id coa ed wi h ca bon and d ied unde labo a o y condi ions, and he NPs size dis ibu ion
was e alua ed by JMic oVision p og amme wi h app oxima ely 150 NPs analysed pe sample. (www.jmic o isi
on.com).
Soman deg ada ion. The soman deg ada ion expe imen s we e pe o med a he Na ional Ins i u e o
Nuclea , Biological and Chemical P o ec ion a Kamenná in The Czech Republic. The GC–MS sys em (GC7890A/
MSD5975 C, ine XL, Agilen Technologies, USA) equipped wi h au oma ic solid phase mic o-ex ac ion (CTC
PAL, The mo Scien i ic, USA) and HP-5MS silica column (30m × 0.25mm × 0.25µm ilm hickness) moni-
o ed soman deg ada ion. Solid phase mic o-ex ac ion (SPME) de ice wi h 65-mic on polydime hylsiloxane/
di inylbenzene (PDMS/DVB) S able lex Supelco ib e was u ilised o soman ans e and injec ion in o he
GC injec ion po . Bo h so p ion and consequen deso p ion ime was 300s in bo h cases a 30°C and 250°C,
espec i ely. Agi a ion a 500 pm o 180s hen homogenised he sample wi h he ollowing GC empe a u e
p og am was as ollows: 45°C (1min), 15°C/min, 80°C (1min), 25°C /min up o 280°C (5min). The 99.9%
pu e Helium ca ie gas had 1mLmin−1 low a e, and he deg ada ion p oduc s we e de ec ed and de e mined
u ilising MSD ChemS a ion so wa e E.02.02.1431 wi h he NIST 08lib a y o mass spec a.
Th ee di e en samples we e es ed o soman deg ada ion. Thei injec ions in o he GC column was pe -
o med a hou ly in e als o 24h as ollows: 5µl o soman (pu i y > 95%, concen a ion in he esul ing solu ion
was 341µgcm−3) was mixed wi h 15ml o (i) linden leacha e C1 as he con ol expe imen , (ii) HAuCl4 p ecu so
(2.5mmoldm−3 o Au) and (iii) Au1 an aqueous solu ion o linden leacha e con aining Au NPs (2.5mmoldm−3
o Au). Residual concen a ions o soman a e deg ada ion moni o ed o 24h we e i ed using pseudo- i s
o de kine ics and he a e cons an (k) was calcula ed by Eq.(1):
whe e c and c0 desc ibe he pe cen age con en o soman a gi en ime and ime ze o, espec i ely, and is
eac ion ime (h). Soman con e sion was hen calcula ed by Eq.(2).
whe e Xsoman is he pe cen age o soman con e sion and c pe cen age is he con en o soman in ime . The
deg ada ion o soman using sample Au1 was epea ed wo imes.
Analysis o deg ada ion p oduc s. Dec eased soman concen a ion o e ime was obse ed in he samples
desc ibed abo e. All h ee samples we e indi idually ex ac ed a e 24-h soman deg ada ion in o 2 × 3mL
CH2Cl2/MeOH (9:1) o de e mina ion o o med deg ada ion p oduc s. The o ganic ex ac s we e d ied by
Na2SO4 and 1mL aliquo s o each ex ac s we e de i a ised by adding 25µL o BSTFA de i a i e agen (N,O-Bis
(1)
ln
(
c
/
c0
)=−
k
(2)
Xsoman
=
c0
−
c
8
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( ime hylsilyl) i luo oace amide). The eac ion mix u e was shaken by hand and his was ollowed by de i a i-
sa ion o 2h a 40–50°C. Finally, 1µL was aken om each eac ion mix u e o GC/MS sc eening analysis and
mass spec a we e e alua ed by NIST08 da abase.
S a is ical analysis. All g aphs we e c ea ed in MATLAB so wa e (Ma hWo ks, USA). The a i hme ic
mean and s anda d de ia ion o UV–VIS da a, NPs size, ζ-po en ial and he pH alues o Au1-Au5 colloids we e
p ocessed by s anda d o mulae in MATLAB so wa e (Ma hWo ks, USA).
Conclusions
Colloidal nanopa icle p ope ies ensu e ha hey a e e y p omising ca aly ic agen s. Howe e , in addi ion o
he necessi y ha NPs p epa a ion me hods and echniques a e bo h economically and en i onmen ally sus ain-
able, inc easing a en ion in indus ial chemis y now ocuses on ‘g een chemis y’ whe e syn hesis is inspi ed by
p ocesses close o na u e. The e o e, ou Au NPs we e p epa ed and s abilised by eco- iendly phy osyn hesis.
Linden b ac s wa e leacha e was used as he educing and capping agen , and he p epa a ion o Au NPs was
epea ed i e imes o con ol phy osyn hesis ep oducibili y.He e, he phy osyn hesised Au colloid ζ-po en ial
alues mo ed a ound.
-20mV wi h app oxima ely 540nm Au NP abso p ion maxima. The a e age Au NP sizes we e 55 ± 10nm o
quasi-sphe ical NPs and 199 ± 55nm o polygonals. Impo an ly, he phy osyn hesised NPs p epa a ion me hod
was p o en ep oducible, and accep able colloid was con i med in he 5-week pe iod.
In addi ion, he phy osyn hesised Au NPs’ ca aly ic ac i i y was es ablished by soman deg ada ion wi hin
24h. While i was in e es ing o no e ha he HAuCl4 Au NPs p ecu so also p o ed able o deg ade soman,
he Au NPs p o ided much be e ca aly ic ac i i y. This was due o he p e iously men ioned peak a ea o he
PMPA and MPA low-molecula inal p oduc s in he sample, wi h he Au NPs being 12.5 and 3.7 imes highe ,
espec i ely, han soman deg ada ion induced solely by HAuCl4.
In conclusion, his esea ch con i med he high po en ial o bio-nano echnology o ep oducible p epa a-
ion o s able and unc ional nanoca alys s o deg ada ion o haza dous subs ances, and mos impo an ly, hese
ca aly ically ac i e nanoma e ials can be p epa ed by g een bio echnology.
Recei ed: 22 Sep embe 2020; Accep ed: 3 Feb ua y 2021
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Acknowledgemen s
We hank Jay Da is and Ray J. Ma shall o language e iew. This wo k was kindly suppo ed by SGS SP2019/23,
SP2020/70 and SP2020/74. Fu he , he wo k was suppo ed by he Minis y o Educa ion o he Czech Republic
in Scien i ic, G an Agency o he Minis y o Educa ion, Science, Resea ch and Spo s o he Slo ak Republic
and he Slo ak Academy o Sciences ia G an s VEGA 1/0164/17, VEGA 1/0146/18, KEGA 013SPU-4/2019 and
he G an Numbe ed CZ.02.1.01/0.0/0.0/16_019/0000753 unde OP RDE.
Au ho con ibu ions
V.H. p epa ed Au nanopa icles, was esponsible o UV–VIS and pH analysis, managed expe imen al sec ion,
p ocessed measu ed da a and w o e he main manusc ip ex . M.U. and D.P. ocused on he GC analysis o soman
deg ada ion and hei in e p e a ion, P.M. guided ζ-po en ial, G.K., V.H. and Z.K. ocused on he in e p e a ion
o he TEM analysis. All au ho s e iewed he manusc ip .
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