Recei ed: 3 Ma ch 2025
Re ised: 25 Ma ch 2025
Accep ed: 28 Ma ch 2025
Published: 3 Ap il 2025
Ci a ion: González-A jona, D.;
López-Pé ez, G. De elopmen o a
Reliable De ice o ‘Fluo okine ic’
Analysis Based on a Po able Diode
A ay MEMS Fluo ime e . Chemosenso s
2025,13, 128. h ps://doi.o g/
10.3390/chemosenso s13040128
Copy igh : © 2025 by he au ho s.
Licensee MDPI, Basel, Swi ze land.
This a icle is an open access a icle
dis ibu ed unde he e ms and
condi ions o he C ea i e Commons
A ibu ion (CC BY) license
(h ps://c ea i ecommons.o g/
licenses/by/4.0/).
A icle
De elopmen o a Reliable De ice o ‘Fluo okine ic’ Analysis
Based on a Po able Diode A ay MEMS Fluo ime e
Domingo González-A jona * and Ge mán López-Pé ez
Depa men o Physical Chemis y, Facul y o Chemis y, Uni e si y o Se illa, C/P o . Ga cía González 1,
E-41012 Se illa, Spain; [email p o ec ed]
*Co espondence: [email p o ec ed]; Tel.: +34-954557175
Abs ac : A de ice was de eloped o s udy he e olu ion o luo escence spec a as a unc-
ion o ime. A p e iously designed luo ime e based on he diode a ay mini-spec ome e
CM12880MA was used. The con ol and measu emen we e ca ied ou by p og amming a
SAM21D mic ocon olle . Conside a ions ega ding he op imiza ion o acquisi ion speed,
memo y, and compu e in e ace ha e been analyzed and op imized. As a esul , a e y
e sa ile de ice wi h g ea adap abili y, educed dimensions, po abili y, and a low budge
(unde EUR 500) has been buil . The sensi i i y, con olled by he in eg a ion ime o he
pho odiodes, can be adjus ed be ween 10
µ
s and 20 s, hus allowing sampling imes anging
om 10 ms o mo e han 10 h. Unde hese condi ions, chemical a e cons an s om 20 s
−1
o 10
−8
s
−1
can be expe imen ally de e mined. I has a e y wide ope a ing ange o he
kine ic a e cons an de e mina ion, o e six o de s o magni ude. As p oo o he sys em
pe o mance, he oxida ion eac ion o Thiamine in a basic medium o o m luo escen
Thioch ome has been employed. The e olu ion o he emission spec um has been ollowed,
and he decomposi ion a e cons an has been measu ed a 2.1
×
10
−3
s
−1
, a alue which
ma ches hose alues epo ed in he li e a u e o his sys em. A Thioch ome calib a-
ion cu e has also been pe o med, ob aining a de ec ion limi o 13 nM, consis en wi h
li e a u e da a. Addi ionally, he s abili y o Thioch ome has been es ed, being he pho o-
decomposi ion a e cons an s 1.8
×
10
−4
s
−1
and 3.0
×
10
−7
s
−1
, in he p esence and absence
o UV ligh (365 nm), espec i ely. Finally, expe imen s ha e been designed o ob ain, in
a single measu emen , he alues o bo h a e cons an s: he o ma ion o Thioch ome
om Thiamine and i s pho o-decomposi ion unde UV ligh o a non- luo escen p oduc .
The a e cons an alues ob ained a e in good ag eemen wi h hose p e iously ob ained
h ough independen expe imen s unde he same expe imen al condi ions. These esul s
show ha , unde hese condi ions, Thioch ome can be conside ed an uns able in e media e
in a chemical eac ion wi h successi e s ages.
Keywo ds: luo escence; chemical kine ic; MEMS spec ome e ; po able de ice;
mic ocon olle
;
Thiamine; Thioch ome; cos e ec i e
1. In oduc ion
This s udy ocusses on he de elopmen o a sys em capable o pe o ming luo okine -
ics analysis by using a Mic o-Elec o-Mechanical Sys em (MEMS)-based mini-spec ome e ,
adap ed as a luo ime e , con olled and ope a ed by a mic ocon olle . The de ice is p o-
g ammed unde he open-sou ce so wa e decla a ion (FOSS) [
1
]. As an ini ial applica ion,
a kine ic s udy o he e olu ion o he luo escen p oduc p oduced in he oxida ion o
Thiamine (TA) has been ca ied ou .
Chemosenso s 2025,13, 128 h ps://doi.o g/10.3390/chemosenso s13040128
Chemosenso s 2025,13, 128 2 o 16
The applica ion o he phenomenon o luo escence con inues o be a subjec o cu en
in e es in scien i ic publica ions. The e a e nume ous applica ions in he li e a u e o he
de elopmen o luo escen ma ke s, which ha e applica ions in di e se ields, anging om
he de elopmen o luo escen p o ein-based biosenso s ha allow o he moni o ing o
physiological p ocesses [
2
–
4
] o he moni o ing and de ec ion o con amina ion in en i onmen al
wa e , ood samples, and pes icide esidues [
5
–
7
]. Some o hese applica ions use luo okine ics
me hods combined wi h chemome ics o he de ec ion o cance oxins [
8
]. The wo ldwide
economic impac ela i e o luo escen de ec ion de ices is eally impo an in many indus ial
applica ions. Thus, he ood indus y is p ojec ed o each EUR 20 billion in 2025 [
9
], pes icide
and wa e pollu an analyses a e es ima ed o be wo h abou EUR 1.5 billion annually [
10
], and
wa e managemen is expec ed o each app oxima ely EUR 4.5 billion in 2027 [11,12].
Kine ic luo ome y is also used in he s udy o pho osyn hesis using a echnique called
delayed luo escence using a - ed ligh o exci a ion. Response imes ypically ange om
milliseconds o se e al minu es [
13
]. Recen ly, s a egies ha e been de eloped o imaging
applica ions o luo escen p obes o ATP [
14
], which use longe exci a ion and emission
wa eleng hs ha allow o de ec ion in deep biological samples. In his ield, a e y p omising
luo escen p obe (Bio-SiR) has been p esen ed o he eal- ime imaging o ATP in cance cells,
which is a si- hodamine-based luo opho e [
15
]. I is p esen ed as he i s umo - a ge ing (nea
IR) molecule luo escen p obe o endogenous ATP imaging in eal ime o umo -bea ing mice.
The basic ins umen (ha dwa e) and a p oposed p og am (so wa e) o kine ic measu e-
men s o luo escence spec a a e discussed in his wo k. The de elopmen is ounded mainly
on s udies [
16
,
17
] and he e e ences he ein. Bo h pape s cons i u e he undamen als o he
p oposed sys em, he o me ocusing mainly on ha dwa e equi emen s and he la e on
so wa e basics. The ini ial ad an ages a e ob iously he high ep oducibili y and sensi i i y
al eady demons a ed, he low budge , and po abili y. A new s ep has been aken o de elop
an inexpensi e, po able, and simple diode a ay kine ic luo ime e . Thus, i is possible o
ake ad an age o he bene i s and minimize he d awbacks poin ed ou in he bibliog aphy
(open sou ce, s abili y, sensi i i y, eliabili y, cos , e c.). Mo e speci ically, i is necessa y o
de elop a sys em capable o eco ding luo escence spec a wi h an acquisi ion equency as
wide as possible, minimizing di icul ies de i ed om he slowness in ob aining and s o ing
he measu ed spec a. The p e ious pape p oposes he use o a de elopmen boa d based
on he ATSAMD21G18 [
18
] mic ocon olle o he acquisi ion and con ol o he Hamama su
CA12880MA [
19
] diode a ay spec ome e . The de eloped so wa e was applied o s a iona y
measu emen s o luo escen samples, spec a, and s a ic quan i a i e de e mina ions. The ime
a iable is only employed o he con ol o he spec ome e lines and he ime ha exci a ion
ligh is on, allowing a e y la ge sensi i i y ange. The second pape es ablished he basis o
bo h he ex e nal pa ame e e i ica ion (con olled by using a sp eadshee ) and o he p ecise
ime con ol du ing he measu emen . The add-on mac o so wa e embedded in he sp eadshee
o he con ol o he sys em has been kep and is based on Pa allax Da a Acquisi ion Tools
Release 2B [20] bu using a newe , mo e e sa ile and use - iendly e sion [21].
To e i y he use ulness and eliabili y o he p oposed de ice, i amin B1 o Thia-mine
(TM) has been chosen as a s a ing compound ac ing as a luo escen p ecu so . TM is an
essen ial i amin o human beings, he de iciency o which p oduces he well-known “be ibe i”
synd ome. I mainly a ec s he ne ous and ca dio ascula sys ems when blood le els a e in
he ange o 9–14 nmol/L [
22
]. In he li e a u e, many analy ical me hods can be employed
o TM in es iga ions, such as colo ime ic, luo escence, elec ochemical, chemiluminescence,
elec ochemiluminescence, HPLC, op ical de ec ion by using nanopa icle me hods, e c. [
23
].
The de e mina ion o TM and ela ed compounds ia luo escence has been widely desc ibed
in he li e a u e o mo e han 80 yea s [
24
]. I s sensi i i y and speci ici y ha e been used o
de elop me hods o he de e mina ion o o he compounds ha eac wi h Thiamine [
25
], and
Chemosenso s 2025,13, 128 3 o 16
e en speci ic de ec o s ha e been de eloped o i s de e mina ion [
26
,
27
]. Ryan e al. [
28
,
29
]
de eloped and exhaus i ely desc ibed a kine ic me hod o he analy ical de e mina ion o TM,
which is he me hodological basis o he p esen wo k. Thei me hodology is so well ounded
ha i has been he subjec o unde g adua e eaching ma e ial [
30
]. E en mo e ecen ly, he e
has been some in e es in he s udy o he oxida ion o TM o o m luo escen compounds,
such as Thioch ome (TC) [
23
,
31
,
32
]. The kine ic beha io o hese compounds p o ides a
sui able amewo k o es ing he e sa ili y and limi s o he luo okine ic de ice p esen ed
in his s udy. I o e s many ad an ages in his ield, such as a high sensi i i y o luo escence
measu emen s, as acquisi ion imes, low cos , g ea po abili y, and ull sp eadshee in eg a ion
o expe imen al da a analysis. The esul s a e compa ed wi h hose published in he li e a u e
o e alua e he sys em’s o e all pe o mance.
2. Ma e ials and Me hods
2.1. Expe imen al
Analy ical-g ade chemicals we e pu chased om Sigma Ald ich: Thiamine hyd ochlo-
ide (CAS 67-03-8), Na
3
PO
4·
12H
2
O (CAS 10101-89-0), Na
2
HPO
4
(CAS 7558-79-4), sodium
hyd oxide (CAS 1310-73-2), hyd ochlo ic acid (CAS 7647-01-0) and me cu y (II) chlo ide
(CAS 7487-94-7). Wa e was pu i ied using a Millipo e sys em (Milli-Q Re e ence model),
and all measu emen s we e pe o med a 22
±
2
◦
C. Hellma Sup asil p ecision qua z cells
( ype 101-QS) wi h a ligh pa h o 10 mm we e used o expe imen al measu emen s.
Figu e 1shows a pic u e o he p oposed de ice wi h he main componen s o he sys em.
As can be no ed, i is a po able de ice wi h small dimensions (120 mm
×
80 mm
×
60 mm),
wi h an o e all weigh o 0.4 Kg. As exci a ion sou ces, i con ains an LED (365 nm) and a lase
diode (405 nm), which is included in he G oupGe s boa d 1. The Hamma su C12880MA
has 15 nm o spec al esolu ion and a wa eleng h ange om 340 o 850 nm, allowing one o
acqui e 288 spec um poin s. The cell compa men has a s anda d size o 10 mm wide.
Figu e 1. Image o he p oposed de ice showing he main componen s o he sys em: (a) luo ime e
box, (b) cell and mi o s compa men , (c) cell cap, (d) USB connec ion cable, (e) G oupGe s b eakou
( .1), Hamama su C12880MA spec ome e and ( ) mic ocon olle ATSAMD21G18 boa d. The Eu o
coin is included o size e e ence.
Chemosenso s 2025,13, 128 4 o 16
2.2. ATSAMD21G18 Mic ocon olle Ha dwa e
The cha ac e is ics o he mic ocon olle selec ed in e ms o p ocessing speed,
clock equency (CLK), and in e nal 32 kB SRAM memo y a e in e es ing. Howe e , wo
majo di icul ies we e encoun e ed a he beginning. Fi s ly, he p ocess o ob ain he
in e nally s o ed da a, using he common ead mode, was pa icula ly slow. Secondly,
he a ailable mic ocon olle memo y is limi ed o s o ing he di e en spec a o a
kine ic p ocess. Fu he mo e, in he measu emen p ocess, he e was no possibili y
o educe he noise le el by a e aging wi hou sac i icing i s speed. S a egies o
accele a ing da a acquisi ion, a e aging, and memo y op imiza ion will be explained
in he ollowing sec ions.
Mo e de ailed in o ma ion on hese aspec s can be ound in he Supplemen a y Ma e ials.
2.3. Speeding up he So wa e Code o “analogRead”
Despi e all he ad an ages men ioned in ela ion o he selec ed mic ocon olle ,
he e was an added di icul y wi h he speed o p ocessing he “analogRead” ins uc-
ion, when he de aul compila ion o he high-le el language is employed. This
ins uc ion uses he mic ocon olle analog- o-digi al con e e (ADC) and is essen ial
o eading/s o ing he ligh in ensi y alues o each wa eleng h. A compa a i e
speed s udy o he h ee mic ocon olle s (UNO, 2560, and ZERO) using he compiled
ins uc ion was pe o med o ob ain a comple e spec um o 288 wa eleng h (WL) da a.
The ime equi ed o he i s wo boa ds was abou 37 ms, bu , inc edibly, o he
ZERO boa d, i was abou 250 ms. Undoub edly, he compile used o ansla e he
ins uc ion o his boa d was ine icien and, wi h his iming, he use o he di ec
compiled ins uc ion o ZERO makes i useless o kine ics pu poses. Fo una ely, his
speed issue was poin ed ou on di e en in e ne o ums. On he A duino o um, an
example code o “speeding-up” he analog- o-digi al con e e (ADC) compila ion
was p esen ed [
33
]. This code in ol ed speci ic po con ol o he SAM21D analog- o-
digi al con e e (mo e in o ma ion is a ailable in he Supplemen a y Ma e ials). The
ime equi ed o e ie ing a whole spec um a ies om 8 ms o an a e age o wo
samples o 89 ms o an a e age o 64 samples. A s udy o he e o associa ed wi h he
numbe o a e ages shows ha he s anda d de ia ion is lowe , and he absolu e e o
changes i s sign o an a e age be ween 32 and 64 samples.
2.4. Timing Con ol
One o he mos impo an ad an ages o mic ocon olle s is he p ecise and as
ime con ol. In e nal ime s can be se up o ob ain he numbe o mic oseconds o
milliseconds elapsed since hey we e igge ed. The ime equi ed o pe o m a mea-
su emen p ocess in ol es di e en asks, and each one has i s own ime consump ion.
To pe o m one single measu emen and con ol he lines o he C12880MA, his p ocess
is ully desc ibed in he p e ious pape . The main di e ence is he as e p ocedu e
desc ibed in Sec ion 2.3. Nex , he selec ed numbe o da a poin s mus be s o ed in
he da a ma ix. To ead a new measu emen , he p og am checks whe he he selec ed
sample ime is o e . I he gap ime is la ge enough, he p og am w i es in o Excel and
plo s one WL selec ed alue o check he measu emen e olu ion. Once he gap ime is
o e , he sequence is epea ed un il i eaches he numbe o measu emen s selec ed.
Fo checking pu poses, hose ime alues can be expo ed o Excel by checking he
‘Debug mode’ box in he PLX-DAQ con olle add-on.
A de ailed desc ip ion o he iming p ocess can be ound in he Supplemen a y Ma e ials.
Chemosenso s 2025,13, 128 5 o 16
2.5. Memo y Op imiza ion
Flash EPROM and SRAM memo y ypes a e implemen ed in mic ocon olle s, each
one o hem depending on i s cha ac e is ics, and a e usually assigned a speci ic ask. Thei
o ganiza ion and uses a e widely discussed in he A duino Memo y Guide [
34
]. Di e en
al e na i es o he s o age o kine ic da a ha e been conside ed, especially aking in o
accoun wo undamen al issues: he ime equi ed o hei s o age and he amoun o da a
o be s o ed. The e a e also o he colla e al conside a ions such as minimizing he cos and
complexi y o implemen a ion. Al hough i migh be hough ha he amoun o memo y
a ailable in he mic ocon olle is sca ce, wi h some op imiza ion, i is possible o s o e a
comple e spec um e e y 10 ms, using jus 0.5 kB. In his way, abou 50 comple e spec a
could be s o ed, wi hou consuming he en i e a ailable SRAM memo y. None heless, in
luo escence measu emen s, he a ea o he spec um co esponding o he exci a ion sou ce
can be neglec ed. This ac allows a la ge numbe o spec a o be s o ed in memo y. On
he o he hand, i is possible o s o e mo e han 10,000 poin s i a single WL is selec ed (a
maximum emission). Wi h hese numbe s, he decision was made o use he bes op ion
o e ed by ATSAMD21G18, which implies an easie , cheape , and as e de elopmen , since
i has a solid base in i s ha dwa e, ega ding he spec opho ome e and he de elopmen
o i s so wa e.
In addi ion, he op imiza ion o he a ailable SRAM p o ides a highe s o age speed
wi h a easonable so wa e modi ica ion e o o im and o ganize he measu ed da a spec-
a. Thus, a single a ay a iable is used o s o e he succession o clipped spec a du ing a
kine ic expe imen , once he numbe o wa eleng hs and he o al numbe o wa eleng hs
o be s o ed a e known. This a ay o clipped spec a o di e en acquisi ion imes can
be expo ed as a wo-dimensional able wi h wo ou pu modes: columns con aining he
selec ed WL and ows o he selec ed ime, o he ansposed mode wi h ime in cols/ ows
and WL.
Mo e de ailed in o ma ion abou memo y op imiza ion and o ganiza ion can be ound
in he Supplemen a y Ma e ials.
2.6. Acquisi ion So wa e PLX_DAQ
As desc ibed in p e ious pape s, he main ad an age o using PLX-DAQ so wa e
Release 2B wi h Excel is o ead and w i e speci ic pa ame e s ia USB wi hou ha ing o
eload he code in o he mic ocon olle e e y ime a pa ame e changes. I also allows o
he s o age o he esul s and hei g aphing du ing he measu emen . Mo eo e , using
he di e en checkboxes included in he PLX-DAQ, he p og am low and he pa ame e
e i ica ion and alida ion can be pe o med easily.
One possible d awback is ha he use o an Excel sp eadshee is manda o y, because
his sp eadshee p og am has undamen al RS232 inpu /ou pu con ol p ocedu es,
compa ible wi h USB. Howe e , i s use has been de eloped by PLX-DAQ wi h open
sou ce. Ve sion 2.11 [
21
] has some addi ional imp o emen s, such as he selec ion o
he sp eadshee ha in e ac s wi h he USB in e ace and a debug ou pu ha allows
o sc u inizing possible communica ion p oblems. Howe e , he main d awback is
he s ic language equi ed o build he message syn ax. Special cha ac e s, usually
employed o con ol in he Se ial communica ion in e ace, can in e e e wi h Excel:
comma, spaces, line eed, and ca iage e u n cha ac e s. Thus, i is highly ecommended
o ca e ully ead he use guide.
Figu e 2shows an Excel sc eensho o he con ol da ashee and he PLX-DAQ add-on
(o ange amed) o a dummy expe imen .
Chemosenso s 2025,13, 128 6 o 16
Figu e 2. Sp eadshee sc eensho o he luo okine ics con ol, showing inpu pa ame e s ( ed ame),
debugging in o ma ion abou he iming (g een ame), PLX-DAQ add-on o Excel (o ange ame),
es ima ed pa ame e s (blue ame) and ac ual kine ic da a (cyan ame). See ex o a de ailed desc ip ion.
2.7. Inpu Pa ame e s
The a iables which con ol he luo okine ics expe imen s a e ela ed o he spec o-
scopic and kine ic imes. In he ed ame shown in Figu e 2, he i s column con ains
a b ie desc ip ion o he measu ed pa ame e and employed uni s, i applicable; he second
column con ains in o ma ion abou hei alid ange. The hi d column is used o w i e
he desi ed ac ual alues, and he ou h column con ains hei es ima ion om he ac ual
alues. The ime alue (in
µ
s) o debugging is displayed in he g een ame. Thei alues
a e use ul o addi ional es ing and alida ion o he kine ic measu emen p ocess.
The e a e some in e ela ionships be ween some inpu pa ame e s, and e o s ha e
been made o main ain he maximum pe o mance o he de ice (memo y, ime, WL). Thus,
he numbe o kine ics poin s is limi ed by he numbe o WLs s o ed up o a maximum
o 25kB. The minimum kine ic ime in e al is limi ed by he ime equi ed o ope a e
he CA12880MA. The e o e, once he inpu pa ame e s a e yped in he Excel cells, i is
necessa y o echeck hei alues o e i y ha all de ice limi s a e ma ched (blue ame in
Figu e 2). Thus, he numbe o WLs o be s o ed is es ima ed om he a ailable memo y.
The minimum sampling ime (in milliseconds) is es ima ed om he in e nal ime alues
(in mic oseconds) wi h a 5% inc emen o sa e y. The exac ime a which he i s spec um
is eco ded co esponds o hal he in eg a ion ime o he i s measu emen (see a de ailed
desc ip ion in Supplemen a y Ma e ials).
The ime be ween measu emen s mus be g ea e han he minimum sampling ime. I
he di e ence be ween he sampling ime and he in eg a ion ime is la ge enough (abou
100 ms), i is possible o expo and plo he ac ual kine ic da a du ing he measu emen
p ocess o a single selec ed WL (cyan ame in Figu e 2). In his case, i is highly ecom-
mended no o ope a e he add-on and/o Excel du ing he measu emen p ocess (see
Supplemen a y Ma e ials o mo e in o ma ion). Once he inpu pa ame e s a e se , hey
a e checked and, i necessa y, ecalcula ed. I no e o s a e de ec ed, hey can be alida ed
by ma king he ‘Check_pa ame e ’ checkbox on he add-on o p oceed.
As he comple e da a ma ix o a kine ic expe imen could be e y la ge, PLX-DAQ
2.11 allows one o selec mo e han one da ashee o expo da a. Thus, one da ashee
Chemosenso s 2025,13, 128 7 o 16
con ains he con ol pa ame e s, debugging, and he ADC da a co esponding o he WLs se-
lec ed o plo ing. O he da ashee s can s o e he en i e ou pu ma ix o selec ed ime/WL
da a o di e en expe imen s. This p ocedu e can be a bi icky ini ially, and special ca e
has o be aken o a oid w i ing he ou pu ma ix on he con ol shee o ying o ead he
inpu pa ame e s om he da a ma ix shee . Ano he checkbox, ‘Expo _Da a_ma ix’, is
used o minimize he possible e o o w i ing in o he w ong da ashee .
2.8. Measu emen Rou ines
In addi ion o he usual code o mic ocon olle p og amming, se up and loop,
se e al ou ines ha e been de eloped o e icien ly pe o m each expe imen . The
mos impo an ones a e lis ed he e (mo e de ailed in o ma ion can be ound in he
Supplemen a y Ma e ials).
•Boos ing analogRead p ocedu e: AdcBoos e (A _le el ).
•Gene a e nCLK pulses: F_pulse_clk3MHz(n).
•Managemen o he CA12880MA con ol lines o a single spec um:
F_ eadSpec ome e (Ex_L ).
•Es ima ion o he wa eleng h associa ed om he manu ac u e da a:
Wa eleng h(o de ).
•Compu es he associa ed indexes acco ding o he WL calib a ion da a:
WL_Index_Da a(&w_H, &w_L, &index_H, &index_L ).
•Ou pu ma ix spec a gene a ion by ow:
c ea e_selec ed_ma ix_by_ ow(&Row_Index_L, &Row_Index_H,
&ac ual_col, *ma ix).
•T immed selec ion o he whole da a ma ix, including acquisi ion ime:
p in Da aMa ixExcel(mode, &Row_Index_L, &Row_Index_H, &N_poin s,
&Del a_ms, o _ _ms, *Da a_Ma ix).
•Clean up in Excel da ashee o he pa ame e es ima ion:
Clean_es ima ed_pa am().
2.9. So wa e Flowcha
A e y simpli ied lowcha o he measu emen p ocess is desc ibed in Figu e 3(mo e
de ailed in o ma ion can be ound in he Supplemen a y Ma e ials).
Figu e 3. Simpli ied scheme o he measu emen p ocess. The sequen ial p ocedu e is ope a ed by
p essing he bu on on he luo ime e , ollowing he ex messages om he add-on.
Chemosenso s 2025,13, 128 8 o 16
The de ice is connec ed ia a USB po o a known COM po numbe . The Excel
sp eadshee con aining he enabled PLX_DAQ mac o mus use he same po alue. The INIT
and SETUP p ocesses a e execu ed only once, by w i ing he in o ma ion in he Excel con ol
shee . The p ocedu e is hen con olled by p essing he de ice bu on b ie ly and ollowing
he ins uc ions in he PLX-DAQ ex messages. Once he measu emen has been comple ed,
special ca e should be aken o selec he Excel shee o da a expo . A e expo ing, selec
he con ol shee again o be able o modi y he pa ame e s o a new measu emen . This
p ocedu e is simila o he one al eady explained in he p e ious documen [
16
,
17
]. The
comple e luo okine ics sou ce p og am, wi h mul iple commen a ies, can be ob ained om
he au ho s, upon eques .
3. Resul s and Discussion
As a es o he e sa ili y, capabili y, and accu acy o he designed luo okine ics de ice,
he a e o TC gene a ion om he oxida ion o TM in a basic medium has been s udied.
3.1. TC Fo ma ion om TM E olu ion
As men ioned in he In oduc ion, he eac ion kine ics a e e y well known in he
li e a u e and a e e en used as an example a he highe educa ional le el [
30
]. The
au ho s ecommend using Hg(II) as he oxidan agen in basic media, despi e o he possible
indica ions [
28
,
29
]. TC has an emission maximum a 450 nm when exci ed wi h UV ligh
(365 nm). Figu e 4shows he TC clipped spec um ob ained wi h he luo ime e a e
comple e oxida ion o a 5 ppm TM solu ion in phospha e bu e (pH 12).
Figu e 4. (A) Sc eensho o he pa ame e s employed o ob ain he emission spec um o TC.
(B) Emission spec um ob ained by Hg(II) oxida ion o a 5 ppm TM solu ion a pH 12. O dina e
co esponds o he ADC alues. No blank co ec ion is pe o med.
Figu e 5shows he p og ess o he TM oxida ion wi h he e olu ion o he TC emission
spec um. These plo s can be easily ob ained om he expo ed ma ix o he adia ion
in ensi y da a a he selec ed WLs and imes du ing he cou se o he TC o ma ion eac ion.
The 3D iew is a s iking example o he isualiza ion o luo okine ics measu emen s
ob ained by he designed de ice.
Chemosenso s 2025,13, 128 9 o 16
Figu e 5. Th ee-dimensional e olu ion o TC o ma ion du ing Thiamine oxida ion. Readings o
he ADC con e e o he mic ocon olle a di e en wa eleng hs. Expe imen al condi ions a e
analogous o hose desc ibed in Figu e 4.
When he kine ics a e ela i ely slow (sampling ime abo e 2.0 s), measu emen s can
be made by swi ching o he exci a ion ligh be ween poin s. Howe e , i i is desi ed o
ob ain he a e cons an a ze o ime, measu emen s ha e o be made a he mixing eac an
ea ly s ages wi h sho sampling imes o ob ain a good esolu ion.
Figu e 6shows he e olu ion o he loga i hm alue o he ADC eading a he wa eleng h
o he emission maximum (450 nm). The acquisi ion was ca ied ou o abou hal an hou .
The oxida ion eac ion ends o be a limi ing alue co esponding o he amoun o ini ial TM.
Figu e 6. E olu ion o he na u al loga i hm o he ADC a he wa eleng h o he emission maximum
(450 nm), un il TM deple ion (blue do s). Pseudo- i s -o de analysis o ini ial eac ion imes ( ed
do s and line) and he expe imen al condi ions a e he same as Figu e 4.
Chemosenso s 2025,13, 128 16 o 16
25.
Holzbeche , J.; Ryan, D.E. The luo ime ic de e mina ion o phospha e wi h hiamine. Anal. Chim. Ac a 1973,64, 147–150.
[C ossRe ]
26.
Kusube, K.; Abe, K.; Hi oshima, O.; Ishigu o, Y.; Ishikawa, S.; Hoshida, H. Elec ochemical De i a iza ion o Thiamine in Flow
Injec ion Sys em. Applica ion o Thiamine Analysis. Chem. Pha m. Bull. 1983,31, 3589–3594. [C ossRe ]
27.
Kusube, K.; Abe, K.; Hi oshima, O.; Ishigu o, Y.; Ishikawa, S.; Hoshida, H. De e mina ion o Vi amin K Analogues by High
Pe o mance Liquid Ch oma og aphy wi h Elec ochemical De i a iza ion. Chem. Pha m. Bull. 1984,32, 179–184. [C ossRe ]
28.
Ryan, M.A.; Mille , R.J.; Ingle, J.D., J . In ensi ied Diode A ay De ec o o Molecula Fluo escence and Chemiluminescence
Measu emen s. Anal. Chem. 1978,50, 1772–1777. [C ossRe ]
29.
Ryan, M.A.; Ingle, J.D., J . Fluo ome ic Reac ion Ra e Me hod o he De e mina ion o Thiamine. Anal. Chem. 1980,52, 2177–2184.
[C ossRe ] [PubMed]
30. Bowe , N.W. Kine ic Fluo escence Expe imen o he De e mina ion o Thiamine. J. Chem. Edu. 1982,59, 975–977. [C ossRe ]
31. S epu o, I.I. Thiamine and asculopa hies. P os aglandins. Leuko . Essen . Fa y. Acids. 2005,72, 115–127. [C ossRe ]
32.
Bubeshko, N.N.; S siapu a, V.I.; S epu o, I.I. Fluo escen P ope ies o Thioch ome in Sol en s o Di e en Pola i y. J. Appl.
Spec osc. 2011,78, 337–343. [C ossRe ]
33.
Speeding up Analog ead() a he A duino Ze o. A ailable online: h ps:// o um.a duino.cc/ /speeding-up-analog ead-a - he-
a duino-ze o/426099/1 (accessed on 27 Janua y 2025).
34.
A duino Memo y Guide. A ailable online: h ps://docs.a duino.cc/lea n/p og amming/memo y-guide (accessed on
26 Janua y 2025).
35. Mille , J.; Mille , J. S a is ics and Chemome ics o Analy ical Chemis y, 6 h ed.; P en ice Hall: London, UK, 2010; ISBN 978-0-273-73042-2.
36.
Anwa , Z.; She az, M.A.; Ahmed, S.; Mus aan, N.; Khu shid, A.; Gul, W.; Kha ak, S.-U.-R.; Ahmad, I. Pho olysis o Thioch ome
in Aqueous Solu ion: A kine ic s udy. J. Pho ochem. Pho obiol. B Biol. 2020,203, 111766–111775. [C ossRe ]
37.
Ahmad, I.; Abbas, S.H.; Anwa , Z.; She az, M.A.; Ahmed, S.; Mobeen, M.F.; Mus aan, N.; Gul, W. S abili y-Indica ing Pho ochemi-
cal Me hod o he Assay o Thiamine by Spec opho ome y. J. Spec osc. 2018,2018, 3178518. [C ossRe ]
38.
De ine and Sol e a P oblem by Using Sol e . A ailable online: h ps://suppo .mic oso .com/en-us/o ice/de ine-and-sol e-a-
p oblem-by-using-sol e -5d1a388 -079d-43ac-a7eb- 63e45925040 (accessed on 26 Janua y 2025).
Disclaime /Publishe ’s No e: The s a emen s, opinions and da a con ained in all publica ions a e solely hose o he indi idual
au ho (s) and con ibu o (s) and no o MDPI and/o he edi o (s). MDPI and/o he edi o (s) disclaim esponsibili y o any inju y o
people o p ope y esul ing om any ideas, me hods, ins uc ions o p oduc s e e ed o in he con en .
