Vitamin B1 sensor at neutral pH and improvement by cucurbit[7]uril

Article abstract of DOI:10.1246/bcsj.20190043

Thiamine deficiency is an important issue for many diseases and thus a facile method of detection is clinically important to improve the health of humans. For that purpose, we have developed a new thiamine sensor using starch stabilized copper nanoparticles (CSNP) at neutral pH and also improved the sensitivity of the sensor using cucurbit[7]uril (CB[7]) through host-guest chemistry. Often thiamine is not detected directly, but through the oxidation of thiamine to thiochrome (TC); TC is a fluorescent emitting molecule, through which thiamine has been measured indirectly. Here, we have demonstrated a new approach for a thiamine sensor, based on the formation of TC by the addition of hydrogen peroxide and CSNP. Unlike the other reported thiamine sensors, our method works advantageously at physiological pH conditions (pH 7, 27 °C). Furthermore, addition of CB[7] to TC, increased the sensitivity of the sensor approximately one order magnitude, through encapsulation; which can be reversed upon addition of a stronger competitive guest such as adamantylamine to confirm the encapsulation of TC. Thus, this new thiamine sensor not only performed well under physiological pH conditions, but also improved the fluorescence of TC, when encapsulated by CB[7].

Full text of DOI:10.1246/bcsj.20190043

Advance Publication Cover Page
Vitamin B1 Sensor at Neutral pH and Improvement by Cucurbit[7]uril
Ramesh Prakash, Govindaraj Usha, Karuppasamy Karpagalakshmi, Sundaram Ramalakshmi,
Lakshminarayanan Piramuthu, Cheng Yang, and Narayanan Selvapalam*
Advance Publication on the web June 15, 2019
doi:10.1246/bcsj.20190043
© 2019 The Chemical Society of Japan
Advance Publication is a service for online publication of manuscripts prior to releasing fully edited, printed versions. Entire
manuscripts and a portion of the graphical abstract can be released on the web as soon as the submission is accepted. Note that the
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Publication manuscripts.

Vitamin B1 Sensor at Neutral pH and Improvement by Cucurbit[7]uril
Ramesh Prakash,1 Govindaraj Usha,1 Karuppasamy Karpagalakshmi,1
Lakshminarayanan Piramuthu,1 Cheng Yang,2 and Narayanan Selvapalam 1*
1Center for Supramolecular Chemistry and Department of Chemistry, International Research Center, Kalasalingam Academy of Research and
Education (Kalasalingam University), Krishnankoil, , Tamil Nadu State, India 626-126
Sundaram Ramalakshmi,1
2Key Laboratory of Green Chemistry & Technology of Ministry of Education, College of Chemistry, State Key Laboratory of Biotherapy, and
Healthy Food Evaluation Research Center, Sichuan University, Chengdu, China 610-064.
E-mail: < n.selvapalam@klu.ac.in >
Narayanan Selvapalam
Narayanan Selvapalam received his M.S. and Ph.D. degrees from Mysore University and IIT Delhi, respectively. He is
presently working as Associate Professor at the Kalasalingam Academy of Research and Education (Kalasalingam
University). His research interests include supramolecular chemistry, Chemistry of cucurbiturils and cyclodextrins,
organic synthesis and sensors.
Abstract
Thiamine deficiency is an important issue for many diseases and
thus a facile method of detection is clinically important to
improve the health of humans. For that purpose, we have
developed a new thiamine sensor using starch stabilized copper
nanoparticles (CSNP) at neutral pH and also improved the
sensitivity of the sensor using cucurbit[7]uril (CB[7]) through
host-guest chemistry. Often thiamine has not been detected
directly, but through the oxidation of thiamine to thiochrome
(TC); because TC is a fluorescent emitting molecule, through
which thiamine has been measured indirectly. Here, we have
demonstrated a new approach for thiamine sensor, based on the
formation of TC by the addition of hydrogen peroxide and CSNP.
Unlike the other reported thiamine sensors, our method
superiorly works at physiological pH condition (pH 7, 27º C).
Furthermore, addition of CB[7] to TC, increased the sensitivity
Scheme 1: Thiamine sensor at neutral pH and improvement
by CB[7]
of the sensor approximately one order magnitude, through
encapsulation; which can be reversed upon addition of a stronger
competitive guest such as adamantylamine to confirm the
encapsulation of TC. Thus, this new thiamine sensor not only
performed well at physiological pH condition, but also improved
the fluorescence of TC, when encapsulated by CB[7].
for thiamine have been explored using various methods that
include
HPLC,4
Resonance
Rayleigh
Scattering,5
electrophorosis,6 chemiluminescent,7 electrochemical,8,9 and
fluorescence10,11 methods. Among them, fluorescence method
mostly depends on the conversion of thiamine to TC, because
TC is a fluorescent compound. For example, Cu2+ and Au3+ have
been utilized for the generation of TC from thiamine and
quantified by fluorescence method.12,13 Both Cu2+ and Au3+
could have reacted with thiamine under basic condition, to
generate the S- ion for the cyclization to generate the
thiochrome.2,12,14 Besides, polyphenol capped gold nanoparticles
have converted thiamine to TC under neutral pH, while bare
gold nanoparticles failed to achieve the same.15 On the other
hand, combination of FeSO4 and t-butyl hydroperoxide also
oxidized thiamine to TC, without utilization of NaOH.16 In
contrast to this, glutathione decorated copper nanoparticles were
used as a fluorescent probe for thiamine, in which thiamine was
quenched by the fluorescent copper nanoparticles and no
conversion of thiamine to TC involved.17 Besides, no report was
found in literature utilizing copper nanoparticles for the
conversion of thiamine to TC, especially at neutral pH condition.
At basic pH, many of the proteins and enzymes are not stable
Keywords:Thiamine sensor, Cucurbituril, Thiochrome
1. Introduction
Thiamine deficiency is a major cause for the deadly disease,
beriberi, which causes nausea and discomfort in pregnant
women, AIDS patients, and induces sudden heart failure at
severe conditions.1 Thus, people at risk of thiamine deficiency
should be monitored with the help of a facile thiamine sensor
and such a sensor can be utilized for food and other related
analyses.2 Indeed, thiamine has been measured clinically
through the formation of thiochrome (TC), by the oxidation of
thiamine under alkali conditions.2 Among the various oxidation
agents, ammonium ferricyanide has been widely employed for
the conversion of thiamine to TC.3 In biochemical analyses,
fluorescence measurement has been considered preferably in
comparison to absorbance to avoid the signals of proteins, as
proteins and DNA absorb in the UV range. Until now, sensors

and thus a sensor at physiological pH is highly beneficial for the
direct biochemical analysis of thiamine.
3 mL of DI water and added to 97 mL of 1 % starch solution and
the pH of the solution was adjusted to 10 by the addition of
ammonia solution, which rendered a dark precipitate. To that
10% ascorbic acid (6 mL) was added, which act as a reducing
agent and changed the solution color to yellow and also the pH
of the solution changed to pH 3. After stirring at room
temperature for a few hours, it changed to colorless at first and
then changed to yellowish brown solution. Upon treatment in a
microwave oven for 8 minutes, the solution changed to wine red,
which is found to be very stable for several weeks, without
having any suspension of particles (no precipitate) and rendered
the expected CSNP as wine red colored solution. Finally, it was
centrifuged at 3500 rpm and washed twice with DI water. This
starch decorated nanoparticles are well dispersed in water.
On the other hand, Cucurbit[n]uril (CB[n]; n = 5–14) played a
major role in supramolecular chemistry as they have contributed
in various fields that include drug delivery, transport, sensors,
lasers and many others.18 Among the CB[n] members, CB[7]
holds the optimum size for the encapsulation of many interesting
molecules that include drugs, saccharides, amino acids, peptides,
proteins and many others.19 Another interesting feature of CB[7]
is its excellent water solubility; through which it can enhance the
water solubility of drugs and dyes by the supramolecular
interactions such as encapsulation and hydrogen bonding.20,21
Interestingly, the photo-physical properties of several
fluorescent dyes have been improved drastically by the
encapsulation of CB[7].22,23 Upon encapsulation, the intensity of
fluorescence dyes has enhanced several folds due to the
hydrophobic environment offered by the cavity of CB[7].24
Several applications have been explored with fluorescent dyes
and CB[7] that include live cell imaging, laser applications,
stabilizing the unstable species and many others.25 Recently,
CB[7] encapsulation studies with thiamine (vitamin B1),26
vitamin B6,27 and vitamin B12,28 have been reported by
Macartney et.al. According to them, thiamine has formed 1:1
complex with CB[7] with the binding affinity of 6.5 x 105 M-1.26
In a similar way, we anticipated that the CB[7] may encapsulate
TC, the oxidized product of thiamine, which may help to
improve the sensitivity of thiamine sensor as the encapsulation
tend to enhance the fluorescence intensity of the encapsulated
molecule. When we examined such a hypothesis using thiamine
with starch decorated copper nanoparticles (CSNP), it produced
the fluorescent TC upon addition of H2O2 and addition of CB[7]
to TC, gave an enhanced fluorescence as anticipated (Scheme 1).
Based on these observations, here, we report a new thiamine
sensor with the improved sensitivity through the supramolecular
interaction of CB[7], which will complement the present clinical
analytical methods of thiamine, because the classical method of
thiamine to TC by ferricyanide is still in practice. However, such
oxidation of thiamine to TC has been performed under strongly
alkali conditions.2 Therefore, this CB[7] improved thiamine
sensor will offer a new approach with enhanced fluorescence
intensity for thiamine detection through the encapsulation of TC
by CB[7] and furthermore, it can be measured at physiological
pH condition. We presume that the combination of CSNP and
hydrogen peroxide might have produced free radicals and
hydroperoxides for the effective conversion of thiamine to TC.16
This was confirmed by the utilization of t-butyl hydroperoxide
with CSNP also produced TC. We anticipate that our method
may trigger to explore several new thiamine sensors from the
mixtures of various hydroperoxides and metal nanoparticles or
metal salts.
2.2 General procedure of thiamine sensor using CSNP
Unless and otherwise mentioned in the text, in general,
thiamine (1 mL) and H2O2 (30% solution, 2 mL) were added to
the 300 µL solution of CSNP in water and the pH solutions were
monitored by a pH meter and adjusted it using 0.1 M sodium
hydroxide solution. All the fluorescence spectra were recorded
after 45 min time interval to get the optimum results.
2.3. Materials and Characterization
Shimadzu RF-5301- PC spectrofluorophotometer has been
utilized for the measurement of fluorescence spectra. SEM and
TEM were recorded using EVO18 (CARL ZEISS) and Jeol-
JEM 2100 respectively. Shimadzu IR Tracer-100 IR Tracer has
been utilized for recording the FT-IR spectra. Micromeritics
NanoPlus DLS Nano Particle Size analyzer helped to measure
the size of the nanoparticles (Dynamic Light Scattering
measurement). FESEM was recorded in Carl Zeiss microscopy
Ltd, UK & SIGMA. CB[7] was prepared and isolated according
29,30
to the reported procedure.
Thiamine was purchased from
Sisco Research Laboratories Pvt. Ltd., Mumbai, India.
Thiochrome was synthesized based on the reported procedure31
and purified by silica gel chromatography.
3. Results and Discussion
Our initial interest was to explore water soluble CSNP for
the purpose to carry out azide-alkyne cycloaddition reactions.
Based on the reported literature,32 CSNP has been synthesized
conveniently using low cost materials such as copper nitrate and
soluble starch. We have modified the reported procedure of
Thakore et. al. to prepare the well dispersed water soluble
CSNP.32 According to the reported procedure, CSNP at the last
stage was treated in a microwave oven for 45 seconds; but, we
treated it for a longer duration (8 min). Finally, the CSNP was
isolated by centrifugation and washed twice with DI water and
adjusted to the final volume of 15 mL and used it for the analysis
of thiamine (see experimental section). CSNP is stable, when
stored in a closed container in dark and the product is well
dispersed in water upon dilution.
2. Experimental
2.1 Synthesis of CSNP
Copper nitrate 0.1 M (Cu(NO3)2.3H2O, (72 mg) was dissolved in

CSNP was characterized by SEM, TEM, FTIR and particle
size analyser (DLS). According to the TEM (Fig. 1a and 1c), the
particle size of the material could be close to 2–3 nm along with
some larger particles distribution with an average diameter of
120 nm, which were confirmed by the DLS analysis (Fig. 1d)
and more particularly using FESEM (Fig. 1b). Recently, we
have re-examined the CSNP using FESEM, which revealed
precise particle size distributions of these nanoparticles.
However, at higher concentrations, they also again assembled
and appeared like a gel like structure (S1). We presume that the
presence of starch moieties at the surfaces of nanoparticles led to
form different sized nanoparticles through hydrogen bonding as
revealed by FESEM. Furthermore, FTIR also revealed the
presence of starch as confirmed from the significant peak values
of FTIR such as 3400 cm-1 (str of OH) and 1647 cm-1 (bending
of OH), along with fingerprint regions peaks gathered close to
1100 cm-1 (Fig. 1e). Overall, the SEM, TEM, DLS and FTIR
analyses confirmed the formation of CSNP (Fig. 1).32
peroxide (2 mL, 30% H2O2 solution in water) was added to each
vial and collected the fluorescence data after 45 min by exciting
at 356 nm. For that, thiamine hydrochloride of 10-1, 10-2, 10-3,
10-4, 10-5 and 10-6 M were prepared in DI water and the pH of
solutions were adjusted to neutral by adding 0.1 M sodium
hydroxide solution. From the measured fluorescence intensity of
TC that emerged from these concentrations indicated that the
lowest sensitivity for thiamine by this method could be close to
10-5 M concentration (S2).
Based on that, we could also get the calibration curve for
thiamine for the quantification of thiamine in food and
pharmaceutical products. For accurate concentration
measurement, we need to prepare the calibration curve within
the specific range; from which, we can find the exact
concentration of thiamine of unknown sample. To demonstrate
that, we have prepared calibration curve for the thiamine
samples prepared at various concentrations falling in the range
of 10-3 to 10-4 M (Fig. 2). From the λmax (452 nm) of emitted
fluorescence intensities of TC, we prepared the calibration curve,
which provided a liner curve (Fig. 2). From the calibration curve,
thiamine concentration of unknown sample can be estimated.
Thiamine is attracted to us because it is an integral part of the
carbohydrate metabolism, which affects the neural activity of
human body and thus early detection may be useful to avoid
health problems. Thiamine can be oxidised to TC by several
reagents that include hexacyanoferrate, mercury and copper ions
and also by hydrogen peroxide in combination with enzymes33
or crude extract of Kohlrabi.34 At initial stage, we examined the
oxidation of thiamine using hydrogen peroxide alone, which
gave no fluorescent compound, as no formation of TC occurred
with H2O2 alone. Nevertheless, oxidation reaction became
successful, when we used the combination of hydrogen peroxide
with CSNP. More precisely, CSNP (300 µL, stock solution) was
added to the solution of thiamine (1 mL) solutions of various
concentrations that were prepared in water and to that hydrogen
Figure 2. Calibration curve for thiamine (10-4 to 10-3 M, R2 =
0.9969)
Surprisingly, the sensitivity of the sensor is time dependant
and observed the maximum sensitivity at 45 min and thereafter it
displayed only a minor variation as shown in fig. 3. We carried
out the time dependant study of thiamine to TC under various
conditions such as long duration (120 min) (S3) and at lower
concentration of thiamine (S4), showed no variation.
Furthermore, addition of host (CB[7]) also not altered the
catalytic duration (S5). We presume that no further thiamine is
available for oxidation at the end of this catalytic reaction by 45
min. To confirm that we compared the fluorescence intensity of
pure TC with that of the TC that got converted from thiamine
under identical concentrations (S6). Both pure TC (10-3 M) and
TC that was converted from thiamine rendered well matched
fluorescence spectrum indicating that the conversion of thiamine
to TC was quantitative. Therefore, all the experiments were
recorded after 45 min, by which it reached the maximum
intensity (Fig. 3). Fragoso et. al. have studied the kinetics of
thiamine to TC conversion and that also revealed a similar time
interval when treated with Hg2+ under basic conditions.35 Many
of the thiamine sensors can work only at basic pH conditions.2,36
Perez-Ruiz et.al. have studied extensively the thiamine sensor
with copper ions, which works effectively under extremely basic
conditions.36 Similarly, other oxidation agents such as
ferricyanide also excelled only in basic conditions, which
intrigued us to examine the effectiveness of our system under
various pH conditions. Thus, we have examined the sensing
potential of CSNP at various pH conditions using 10-1 M of
thiamine. Surprisingly, unlike other reported thiamine sensors,
CSNP displayed the best performance only at neutral pH (pH 7.0,
27º C) (Fig. 4), which is a marked difference from other
Figure 1. TEM (a and c), SEM (b), DLS (d) and FTIR (e) of
CSNP

thiamine sensors reported. As it worked at physiological pH
condition, it could be an added advantage compared to other
reported thiamine sensors. When compared with the other TC
based system, the present system furnished worst results at basic
pH and worked better at acidic pH conditions and offered best at
the intensity of the fluorescence, which helped to study many
applications that include label free enzyme analysis and many
others. In that way, we decided to examine the interaction of TC
with CB[7]. For that reason, we added 1 mL of 10-3
M
concentration of CB[7] to the mixture of thiamine (1 mL), CSNP
(300 µL) and hydrogen peroxide (2 mL) . Addition of CB[7] (1
mL of 10-3 M) to the solutions of thiamine containing CSNP (all
concentrations), exhibited an enhanced fluorescence and
reached to the maximum sensitivity level of 10-6
M
concentration of thiamine in water (Fig. 5), which is one order
magnitude superior than the sensor prepared without CB[7] (S2,
Figure 3. Time dependant fluorescence emission of thiamine
sensor by the addition of CSNP and H2O2
neutral pH. This is quite unique and the mechanism of the action
is not fully understood and we presume that copper
nanoparticles in combination with hydrogen peroxide could
have generated the free radicals such as hydroperoxides, which
helped for the oxidation of thiamine. Thiamine is stable in
neutral and acidic pH, however the formation of an intermediate
compound having sulfide ion (S-) and aldehyde is the key
intermediate for the cyclization of thiamine, which required the
Figure 5. Improved sensitivity of thiamine sensor by the
addition of CB[7] (constant volume, 1 mL,1 x 10-3 M) to the
solutions of thiamine (10-1 to 10-6 M)
basic conditions.2,14
. Although, polyphenol capped gold
S8). In order to understand the precise encapsulation effect, we
used identical concentration of thiamine and CB[7]. For
example, the intensity of the spectrum obtained by the addition
of CB[7] (10-3 M) to thiamine (10-3 M) equalled to the spectrum
obtained from the higher concentration of thiamine (10-2 M),
indicating that CB[7] can improve the sensitivity of thiamine
sensor (S7) by at least one order magnitude (Fig. 6)
nanoparticles exhibited the conversion of thiamine to TC at
neutral pH, however, no peroxide has been used.15 Similarly, the
mixture of FeSO4 and t-butyl hydroperoxide also converted
thiamine to TC.16 We presume that the CSNP may follow the
mechanism of FeSO4 for the oxidative preparation of TC as both
involved peroxides. Hydroperoxides are known to oxidize
thiamine to TC under neutral condition.16 To confirm this fact,
we examined the combination t-butyl hydroperoxide and CSNP
for the oxidation of thiamine. Surprisingly, this combination also
produced the TC, which affirmed the involvement of
hydroperoxide during the oxidation of thamine (S7).
Since thiamine can be encapsulated by CB[7],23 we
anticipated that TC, an intramolecular cyclised product, may
also preferred by CB[7], and if encapsulation occurs, that can be
observed explicitly from the enhancement of fluorescence
originated from TC. As CB[7] is a water soluble host molecule,
it can attract drugs and dyes into the hydrophobic cavity of
CB[7] and that will provide stability and improvement in
photo-physical properties of dyes. More specifically,
encapsulation of fluorescent molecules by CB[7] would enhance
The host molecule, CB[7] has the potential to encapsulate
the thiamine as well as the oxidized product of thiamine (TC)
inside the hydrophobic cavity of the host, which often evidenced
by the enhancement of the fluorescent signal. On the other hand,
if we add a competitive guest such as adamantylamine, to the
guest (TC) encapsulated CB[7] solution, which may end up with
the elimination of TC from the cavity of CB[7] and that will
reduce the intensity of TC from the original intensity due to the
lack of inclusion.19,20 To demonstrate this inclusion and
exclusion phenomena of TC, with CB[7], we have employed the
identical concentrations of 10-3 M thiamine, CB[7] and
adamantylamine. As shown in Fig. 6, addition of CB[7] to the
TC containing solution, resulted an enhancement of
fluorescence due to the encapsulation of TC by the host CB[7].
Figure 4. Effect of pH on the conversion of thiamine to TC using
Figure 6. Confirmation of TC encapsulation by CB[7] using the
CSNP (10-1 M of thiamine)
competitive guest (adamantylamine)

Figure 7. Estimation of thiamine using commercial
pharmaceutical sample from the calibration curve of
thiamine (10-4 to 10-3 M)
Figure 8. Naked eye detection of thiamine sensor: Thiamine
sensor without CB[7] (a and c); thiamine sensor with CB[7] (b
and d).
On the other hand, addition of adamantylamine to the solution
containing TC and CB[7], reduced the intensity of the solution
back to the original due to the exclusion of TC from the cavity of
CB[7]. Besides, addition of 1,4, diaminobutane to the mixture of
TC and CB[7] did not affect the intensity, because 1,4,
diaminobutane guest cannot form a good inclusion complex
with CB[7] (S9) due to the size mismatch of the host and guest.
We presume that the role of CB[7] can be implemented in other
reported thiamine sensors, where TC is involved to enhance the
sensitivity of the sensor.
product is a blue fluorescent compound (TC). As displayed in
fig. 8a, thiamine did not produce the TC, when it was treated
only with H2O2. Similarly, CSNP did not produce any
fluorescent compound when it was treated only with H2O2;
however, the combination of CSNP, thiamine and H2O2 rendered
the fluorescent compound (TC). Addition of CB[7] to it also
improved the fluorescence intensity of the solution (Fig. 8b).
However, without CB[7] the detection range of thiamine reached
to the maximum of
10-3
M concentration (Fig. 8c).
The encapsulation of TC by CB[7] was further evidenced
from 1H NMR experiments. For that purpose, we have
synthesized TC by the reported procedure28 and recorded the
NMR after the addition of CB[7], which revealed a weak
complexation of TC with CB[7] (S10, S11). The peaks of CB[7]
were disturbed by the encapsulation of TC and the methyl
protons of the 5 membered ring of TC has shifted downfield as
they are now located near to the portals of CB[7]. We presume
that unlike thiamine, TC can be bulkier for the hydrophobic
cavity of CB[7] and thus formed a weak complex with CB[7].
This was further supported by the spectroscopic measurement of
binding constant for encapsulation of TC and CB[7] (S12). The
binding constant was found to be 7.7 x 103 M (S13). A detailed
study is required to understand the complexation nature of TC
with CB[7], that include X-ray crystallography and ITC
experiments. Indeed, X-ray crystallography studies may give us
a clear picture of such encapsulation phenomenon.
Nevertheless, addition of CB[7] to the mixture of CSNP,
thiamine, H2O2, helped to visualize thiamine to the maximum of
10-4 M concentration as shown in fig. 8d. Overall, we could
demonstrate the utility of CB[7] in thiamine sensor, as it
improved the sensitivity of thiamine sensor at least one order
magnitude higher than the routine method. We believe that these
results may be extendable to the other vitamin sensors and
similar works are in progress.
4. Conclusion
In conclusion, a new approach for thiamine sensor based
on the oxidation of thiamine using hydrogen peroxide and water
soluble CSNP has been reported here. The oxidative product, TC
is a fluorescent compound, which can be monitored by
spectrofluorometer. Unlike the other reported thiamine sensors,
which worked only under basic conditions; our system worked
efficiently at physiological pH condition (pH 7). Furthermore,
addition of CB[7] also improved the sensitivity of the sensor
approximately one order magnitude, by the effect of
encapsulation. The encapsulation of TC has been proved by the
addition of a stronger competitive guest such as adamantylamine.
This methodology can be extendable to other thiamine sensors,
in which the sensitivity can be redefined. We believe that these
results may be extendable to the other vitamin sensors and
similar works are in progress.
In order to know the practicability of the thiamine sensor,
we have quantified the commercial capsules of thiamine sold in
the drug store. For that, 100 mg thiamine hydrochloride capsules
were digested in water (10 mL) and removed the insoluble
sediments by centrifugation. Water soluble portion was further
diluted (1 mL to 40 mL), which rendered 7.4 x 10-4 M solution.
We also prepared the thiamine concentrations in the range of 10-3
to 10-4 M. Using those solutions, we obtained calibration curve
as shown in Fig.7. Subsequently, we measured the intensity of
the commercial tablet solution after the addition of CSNP,
hydrogen peroxide and CB[7]. For example, the intensity of the
commercial thiamine sample (7.4 x 10-4 M) rendered the
concentration of 6.2 0.5 x 10-4 M, which is much closer to the
expected concentration range considering the errors involved in
manufacturing/ handling/dilution (Fig.7). To reaffirm the results,
we prepared two different solutions of identical concentrations
from the sources of pure thiamine and commercial tablets and
compared their fluorescence spectrum, which also revealed the
loss of intensity for the sources of commercial pharmaceutical
capsules (S14)
Acknowledgement
This work is financially supported by DST- SERB, India under
Early Career Research Award (ECR/2015/000318). R. P thanks
to the KARE for University PhD fellowship. G. U. thanks to the
SERB for Project Assistant fellowship. The authors thank Dr.
Shasi Anand, the Vice President of KARE, for the research
support and encouragement.
The catalytic activity of CSNP on thiamine can be
visualized by naked eye under UV light (365 nm), since the final
References

1.
2.
H-S. Lee, S-A. Lee, H-S. Shin, H-M. Choi, S-J. Kim, H-K.
Kim, Y-B. Park, Korean Circ. J. 2013, 43, 569
K. A. Edwards, N. Tu‐Maung, K. Cheng, B. Wang, A. J.
Baeumner, C. E. Kraft, Chemistry Open. 2017, 6, 178.
N. Grekas, A. C. Calokerinos, Talanta 1990, 37, 1043.
A. Schmidt, H. Pratsch, M. G. Schreiner, H. K. Mayer,
Food Chem. 2017, 229, 452.
27. W. Li, S. Li, I. W. Wyman, D. H. Macartney, Q. Zhang, Y.
Zheng, R. Wang, J. Nanomater., 2015, 574013,
DOI:10.1155/2015/574013.
28. R. Wang, B. C. MacGillivraya, D. H. Macartney, Dalton
Trans. 2009, 18, 3584.
3.
4.
29. J. Kim, I.-S. Jung, S.-Y. Kim, E. Lee, J.-K. Kang, S.
Sakamoto, K. Yamaguchi, K. Kim, J. Am. Chem. Soc.
2000, 122, 540.
5.
6.
7.
8.
9.
Q. Wang, Z. F. Liu, L. Kong, S. P. Liu, Chin. J. Anal. Chem.
2007, 35, 365.
30. A. I. Day, A. P. Arnold, R. J. Blanch and B. Snushall, J.
Org. Chem. 2001, 66, 8094.
J. Bai, X. Hun, Q. Liu, J. C. Chen, L. Bai, Microchim. Acta.
2016, 160, 165.
31. G. E. Risinger, P. N. Parker, Experientia, 1965, 21, 305
32. M. Valodkar, P. S. Rathore, R. N. Jadeja, M. Thounaojam,
R. V. Devkar , S. Thakore, J. Hazard. Mater. 2012, 201,
244.
M. Kamruzzamana, A. M. Alama, S. H. Leea, T. D. Dang,
Sens. Actuators B
Z. Zhou, C. L. Tan, Y. H. Zheng, Q. M. Wang, Sens.
Actuators B Chem. 2013, 188, 1176.
AA. Ciszewski, J. Wang, Analyst, 1992, 117, 985.
‐Chem. 2013, 185, 301.
‐
33. M. A. Khan, S. O. Jin, S. H. Lee, H. Y. Chung.
Luminescence 2009, 24, 73.
10. M. Zeeb, M. R. Ganjali, P. Norouzi, Microchim. Acta.
2010, 168, 317.
34. M, Amjadi, J. L. Manzoori, M. Orooji, Bull. Korean Chem.
Soc. 2007, 28, 246.
11. G. D. Tarigh, F. Shemirani, Talanta 2014, 123, 71.
12. Y. Yu, Y. J. Ching and Y. N. Tan, Austin. J. Biosens. and
Bioelectron. 2015, 1, 1004
35. W. D. Fragoso, A. C. Olivieri, Microchem. J., 2016, 128,
42
36. T. Perez-Ruiz, C. Martinez-Lozano, V. Tomas, I. Ibarra
Talanta, 1992, 39, 907.
13. T. Perez-Ruiz, C. Martinez-Lozano, V. Tomas, I. Ibarra,
Talanta 1992, 39, 907.
.
14. G. Perez-Caballero, J. F. Perez-Arevalo, E. A.
.
Morales-Hipolito,
M.
E.
Carbajal-Arenas,
A.
Rojas-Hernandez, J. Mex. Chem. Soc. 2011, 55, 126.
15. K. J. Rao, S. Paria, RSC Adv., 2014, 4, 28645.
16. P. I. Lukienko, N. G. Mel'nichenko, I. V. Zverinskii, S. V.
Zabrodskaya, B. Exp. Biol. Med. 2000, 130, 874.
17. Y. Luo, H. Miao, Yang, Talanta 2015, 144, 488.
18. (a) K. Kim, J. Murray, N. Selvapalam, Y. H. Ko, I. Hwang
(2018), World Scientific. Singapore: Cucurbiturils:
Chemistry, supramolecular chemistry and applications;
(b) J. W. Lee, S. Samal, N. Selvapalam, H.-J. Kim, K. Kim,
Acc. Chem. Res. 2003, 36, 621; (c) S. J. Barrow, S. Kasera,
M. J. Rowland, J. D. Barrio, O. A. Scherman, Chem. Rev.
2015, 115, 12320; (d) K. I. Assaf, W. M. Nau., Chem. Soc.
Rev. 2015, 44, 394; (e) V. Montes-Garc´ıa, J. Perez-Juste, I.
Pastoriza-Santos, L. M. Liz-Marzán, Chem. Eur. J. 2014,
20, 10874; (f) Y. Shen, L. Zou, Q. Wang, New J. Chem.
2017, 41, 7857; (g) S. Pan, S. Mondala, P. K. Chattaraj,
New J. Chem. 2013, 37, 2492; (h) M. Junpei, C. Yoshiki,
Chem. Lett. 2008, 37, 312; (i) K. M. Park , J. Kim, Y. H.
Ko , Y. Ahn , J. Murray , M. Li , A. Shrinidhi, K. Kim, Bull.
Chem. Soc. Jpn. 2018, 91, 95.
19. a) E. Masson,
X. Ling,
R. Joseph, L.
Kyeremeh-Mensaha, X. Lua, RSC Adv. 2012, 2, 1213; b)
H. Yin, R. Wang, Isr. J. Chem. 2018, 58, 188; c) G. Ghale,
W. M. Nau, Acc. Chem. Res. 2014, 47, 2150.
20. M. J. Webber, R. Langer, Chem. Soc. Rev. 2017, 46, 6600.
21. K. I. Kuok, S. Li, I. W. Wyman, R. Wang, Ann. N. Y. Acad.
Sci. 2017, 1398, 108.
22. R. Prakash, G. Usha, L. Piramuthu, N. Selvapalam, Chem.
Lett. 2017, 46, 1300; b) Y. Xia, S. Chen, X-L. Ni, ACS
Appl. Mater. Interfaces 2018, 10, 13048.
23. R. Prakash, G. Usha, P. Sivaranjana, K. Karpagalakshmi,
L. Piramuthu, N. Selvapalam, New J. Chem. 2018, 42,
13038; b) H. Yin , F. Dumur, Y. Niu, M. M. Ayhan, O.
Grauby, W. Liu, C. Wang, D. Siri, R. Rosas, A. Tonetto, D.
Gigmes, R. Wang, D. Bardelang, O. Ouari, ACS Appl.
Mater. Interfaces 2017, 9, 33220.
24. W. M. Nau, J. Mohanty, Int. J. Photoenergy. 2005, 7, 133.
25. R. N. Dsouza, U. Pischel, W. M. Nau, Chem. Rev. 2011,
111, 7941.
26. S. Li, H. Yin, I. W. Wyman, Q. Zhang, D. H. Macartney, R.
Wang, J. Org. Chem. 2016, 81, 1300