β-AgVO3 Nanorods as Peroxidase Mimetic for Colorimetric Determination of Glucose

Article abstract of DOI:10.1002/jccs.201700031

β-AgVO₃ nanorods have been demonstrated to exhibit intrinsic peroxidase-like activity. The oxidation of glucose can be catalyzed by glucose oxidase (GOx) to generate H₂O₂ in the presence of O₂. The β-AgVO₃ nanorods can catalytically oxidize peroxidase substrates including o-phenylenediamine (OPD), 3,3′,5,5′-tetramethylbenzidine (TMB), and diammonium 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) by H₂O₂ to produce typical color reactions: OPD from colorless to orange, TMB from colorless to blue, and ABTS from colorless to green. The catalyzed reaction by the β-AgVO₃ nanorods was found to follow the characteristic Michaelis–Menten kinetics. Compared with horseradish peroxidase and AgVO₃ nanobelts, β-AgVO₃ nanorods showed a higher affinity for TMB with a lower Michaelis–Menten constant (K_m) value (0.04118 mM) at the optimal condition. Taking advantage of their high catalytic activity, the as-synthesized β-AgVO₃ nanorods were utilized to develop a colorimetric sensor for the determination of glucose. The linear range for glucose was 1.25–60 μM with the lower detection limit of 0.5 μM. The simple and sensitive GOx-β–AgVO₃ nanorods–TMB sensing system shows great promise for applications in the pharmaceutical, clinical, and biosensor detection of glucose.

Full text of DOI:10.1002/jccs.201700031

JOURNAL OF THE CHINESE
CHEMICAL SOCIETY
Article
β-AgVO3 Nanorods as Peroxidase Mimetic for Colorimetric Determination of Glucose
*
*
Junyu Lu, Lianqiang Wei, Dongmei Yao, Xiuju Yin, Hongfang Lai and Xiuxiang Huang
College of Chemistry and Biology Engineering, Hechi University, Yizhou 546300, China
(Received: January 22, 2017; Accepted: April 5, 2017; DOI: 10.1002/jccs.201700031)
β-AgVO3 nanorods have been demonstrated to exhibit intrinsic peroxidase-like activity. The oxi-
dation of glucose can be catalyzed by glucose oxidase (GOx) to generate H2O2 in the presence of
O2. The β-AgVO3 nanorods can catalytically oxidize peroxidase substrates including o-
phenylenediamine (OPD), 3,30,5,50-tetramethylbenzidine (TMB), and diammonium 2,20-azino-bis
(3-ethylbenzothiazoline-6-sulfonate) (ABTS) by H2O2 to produce typical color reactions: OPD
from colorless to orange, TMB from colorless to blue, and ABTS from colorless to green. The cat-
alyzed reaction by the β-AgVO3 nanorods was found to follow the characteristic Michaelis–
Menten kinetics. Compared with horseradish peroxidase and AgVO3 nanobelts, β-AgVO3 nanor-
ods showed a higher affinity for TMB with a lower Michaelis–Menten constant (Km) value
(0.04118 mM) at the optimal condition. Taking advantage of their high catalytic activity, the as-
synthesized β-AgVO3 nanorods were utilized to develop a colorimetric sensor for the determina-
tion of glucose. The linear range for glucose was 1.25–60 μM with the lower detection limit of 0.5
μM. The simple and sensitive GOx-β–AgVO3 nanorods–TMB sensing system shows great promise
for applications in the pharmaceutical, clinical, and biosensor detection of glucose.
Keywords: β-AgVO3 nanorods; Peroxidase-like activity; Colorimetric assays; Glucose detection.
INTRODUCTION
Because of its low cost, simplicity, and fast detec-
In recent years, a number of nanomaterials have
emerged owing to the widespread development of
nanoscience and technology. They have been widely
applied in various fields because of their intrinsic
advantages such as low cost, easy preparation and puri-
fication, good stability, and stable storage. Some of
nanomaterials have shown potential for colorimetric
sensing.5 Hupp et al.6 used an Au-nanoparticle-based
colorimetric sensor for the determination of heavy
metal ions. However, the change of color based on Au
nanoparticles was dependent on their size, capping
agents, and shape.7 These drawbacks limit their appli-
cation. To overcome these shortcomings, many
attempts have been made to develop peroxides
mimetics. Since Yan’ group8 showed that inorganic
materials of Fe3O4 magnetic nanoparticles possess
intrinsic peroxidase-like activity, a number of the inor-
ganic materials were found to possess enzyme-like
activity. Such materials include metallic oxide nanopar-
ticles (CeO2,9 Co3O4,10 V2O5,11 CuO,12 and MnO2,13),
metallic and bimetallic nanostructures (Au,14 Ag,15
Pt,16 AFt-Fe-Pt,17and Au@PtAg18), carbon-based
tion, colorimetric sensing is considered a very important
method in analytical chemistry. Significantly, it can be
employed during field analysis using only naked eyes.
Colorimetric sensing does not demand any expensive or
complicated instrumentation because the changes of
color can be directly visualized.1 However, this analyti-
cal method also faces some challenges, including how
to turn the detection events into obvious color
changes.2 Today, peroxidase working as colorimetric
sensing agent has been extensively approved in many
fields. It can catalytically oxidize substrates including o-
phenylenediamine (OPD), 3,30,5,50-tetramethylbenzidine
(TMB), and diammonium 2,20-azino-bis(3-ethylben-
zothiazoline-6-sulfonate) (ABTS) to generate color
changes.3 Unfortunately, the natural enzyme suffers
from some intrinsic disadvantages, for example, lack of
stability, tedious preparation and purification processes,
and inactivity under harsh conditions. In order to over-
come these shortcomings, many efforts have been made
to develop peroxidase mimetics.4
*Corresponding authors. Email: laihongfang263@163.com; hxx1372@sina.com
J. Chin. Chem. Soc. 2017
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Article
Lu et al.
nanomaterials (graphene oxide,19 carbon nanotubes,20
carbon dots21), and bimetallic oxide nanoparticles
(ZnFe2O4,22 CoFe2O4,23 FeWO4,24 and NiFe2O425),
which have been applied in colorimetric sensing based
on their peroxides-like activity. Among them, the bime-
tallic oxide alum was not included until Zhang et al.26
reported that AgVO3 nanobelts exhibited intrinsic
peroxidase-like activity. However, AgVO3 nanobelts
had a large size, which affected its catalytic activity.
Yan et al.8 found that the smaller the size of a nano-
zyme, the higher its catalytic activity due to the larger
surface area for interaction with substrates. Therefore,
developing smaller alum bimetallic oxides with
peroxidase-like activity still remains a challenge.
In this work, a simple and easy hydrothermal
method was used for the preparation of small β-AgVO3
nanorods. The catalytic activity of these nanorods was
investigated by the catalytic oxidation of TMB to pro-
duce a typical blue color reaction in the presence of
H2O2. Glucose oxidase (GOx) could catalyze the oxida-
tion of glucose to generate H2O2 (Scheme 1). Based on
these findings, a simple and quick colorimetric method
was developed to determine glucose in serum samples.
from Shantou Xilong Chemical Factory (Guangdong,
China). TMB, ABTS, and OPD were purchased from
TCI (Shanghai, China). Silver nitrate (AgNO3), partial
ammonium vanadate (NH4VO3), glucose, lactose, fruc-
tose, ascorbic acid (AA), and tert-butyl alcohol were
purchased from Aladdin Chemistry Co. Ltd (Shanghai,
China). GOx, horse radish peroxidase (HRP), and glu-
tathione (GSH) were obtained from Sigma-Aldrich
(St. Louis, MO, USA). Ultrapure water was produced
by a Millipore purification system (Bedford, MA, USA)
and used to prepare all aqueous solutions. Human
serum samples were obtained from the Five People’s
Hospital of Guilin (Guilin, China). All experiments
were performed in compliance with the relevant laws
and institutional guidelines of the ethics committee of
the hospital, and informed consent was obtained from
the patients who provided the human samples.
Apparatus
Absorption spectra were obtained on a Cary
60 model spectrophotometer (Agilent, Santa Clara, CA,
USA). The powder X-ray diffraction (XRD) patterns of
β-AgVO3 were recorded on a D/max 2550 VB/PC dif-
fractometer (Rigaku,Tokyo, Japan) with Cu Kα radia-
tion (λ = 0.15418 nm). Scanning electron microscopy
(SEM) was carried out on an FEI Quanta 200 FEG
SEM instrument (Philips, Amsterdam, Netherlands).
Inductively coupled plasma mass spectrometry (ICP-
MS) was carried out on a Flexar/NexlON300X appa-
ratus (PerkinElmer, Waltham, MA, USA).
EXPERIMENTAL
Chemicals and materials
All chemicals in this work were obtained from
commercial sources and used as received without fur-
ther purification. Unless otherwise stated, all the chemi-
cals were analytical grade. Acetic acid (HAc), calcium
chloride (CaCl2), potassium carbonate (K2CO3), H2O2
(30 wt %), and sodium acetate (NaAc) were obtained
Synthesis of β-AgVO3 nanorods
The β-AgVO3 nanorods were prepared according
to the literature27 with some modification. Typically,
0.170 g of AgNO3 was added to 30 mL ultrapure water
with magnetic stirring. Then, 0.085 g of NH4VO3 was
added to this solution. The mixed solution was continu-
ously stirred for 2 h. The solution was transferred to a
Teflon-lined stainless steel autoclave and heated for
24 h at 180ꢀC. After cooling to room temperature, the
yellow product was isolated by centrifugation and was
washed several times with ultrapure water and ethanol
in order to remove the superfluous reactants. Finally,
the β-AgVO3 nanorods were dried in a vacuum oven
for 6 h at 60ꢀC.
Scheme 1. Schematic illustration of colorimetric
determination of glucose using GOx–β-
AgVO3 nanorod-catalyzed reactions.
2
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Colorimetric Sensing; Glucose Detection
Mimetic peroxidase activity assays
For glucose detection in real samples, the human
serum samples were diluted 20-fold with ultrapure
water. A certain amount of the diluted solution was
added to 10 mM PBS (pH 6.9) and 50 μL of GOx
(1 mg/mL), and various concentrations of the glucose
solutions were spiked. The mixed solution was dealt
with in the same way as the glucose standard. The
mixed solutions were analyzed with the proposed
method, and the percent recovery values were obtained.
In the selectivity experiments, 600 μM AA, 600 μM
fructose, 600 μM K2CO3, 600 μM CaCl2, 600 μM lac-
tose, and 600 μM glutathione were used to replace
60 μM glucose.
All the reactions were monitored in the time-scan
mode at 652 nm using the Cary 60 spectrophotometer.
Kinetic measurements were carried out by monitoring
the absorbance change at 652 nm. A typical catalytic
experiment was as follows: 4.5 μg/mL β-AgVO3 nanor-
ods or 0.3 ng/mL HRP, 0.1 mM TMB, and 8 mM
H2O2 were taken as the substrates in a reaction volume
of 2 mL. The kinetic constants were calculated by
employing the Lineweaver–Burk plots of the double
reciprocal of the Michaelis–Menten equation: 1/ν =
Vmax × [S]/(Km + [S]), where the ν is the initial velocity,
Vmax is the maximum reaction velocity, [S] is the con-
centration of the substrate, and Km is the Michaelis
constant8.
RESULTS AND DISCUSSION
Characterization of β-AgVO3 nanorods
Colorimetric detection of glucose
The β-AgVO3 nanorods were synthesized by a
hydrothermal method. The morphology and structure
of the as-synthesized β-AgVO3 nanorods were identified
by XRD, SEM, and ICP-MS. Figure 1 shows the XRD
patterns of as-synthesized β-AgVO3 nanorods before
and after the catalytic reaction. The diffraction peak
positions coincided with those of the standard cards
(JCPDS 29–1154), which indicated that the prepared
β-AgVO3 nanorods had a well-crystallized structure. At
the same time, it also demonstrated that the as-
synthesized β-AgVO3 nanorods had good stability in
this sensing system. The SEM images showed that the
prepared β-AgVO3 exhibit nanorod-like morphology.
The nanorod diameter was 28–80 nm and the length
was 0.4–1.2 μm (Figure 2). The obtained β-AgVO3
nanorods were smaller than the AgVO3 nanobelts,26
which indicated that the catalytic activity of β-AgVO3
nanorods should be higher than that of the AgVO3
nanobelts. The as-prepared sample was investigated
using ICP-MS (Table 1). This analysis indicated that
the compositions of Ag and V were close to the theoret-
ically calculated values, suggesting that β-AgVO3
nanorods were successfully synthesized.
Colorimetric detection of glucose was carried out
as follows: (a) 50 μL of GOx (1 mg/mL) and 50 μL of
glucose at various concentrations in phosphate buffered
saline (PBS) (10 mM, pH 6.9) were incubated at 37ꢀC
for 30 min; (b) 25 μL of TMB (4 mM), 90 μL of
β-AgVO3 nanorods (0.05 mg/mL), and 585 μL of
0.2 M NaAc–HAc buffer (pH 4.0) were successively
added into the above 300 μL glucose reaction solution;
(c) the mixed solution was incubated at room tempera-
ture for 25 min; and (d) the absorption spectrum of
mixed
solution
was
determined
by
the
spectrophotometer.
Peroxidase-like activity of β-AgVO3 nanorods
The β-AgVO3 nanorods are a kind of inorganic
material with expected enzyme-like activity. The
peroxidase-like activity of β-AgVO3 nanorods was stud-
ied by the catalytic oxidation a typical peroxidase sub-
strate (TMB) via H2O2. As shown in Figure 3(a),
β-AgVO3 nanorods, TMB + β-AgVO3 nanorods,
10
20
30
40
50
60
70
80
2 θ (degree)
Fig. 1. XRD pattern of the β-AgVO3 nanorods
before (black line) and after a catalytic reac-
tion (blue line).
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Article
Lu et al.
a 1.6
b
A
B
D
C
E
1.2
0.8
0.4
0.0
1.2
0.8
0.4
0.0
TMB
OPD
ABTS
E
C
A
B
D
C
B
A
400
600
800
300
400
500
600
700
Wavelength (nm)
Wavelength (nm)
Fig. 3. (a) UV–vis spectra of (A) β-AgVO3 nanorod
solution, (B) TMB + β-AgVO3 nanorods,
(C) TMB–H2O2, (D) H2O2 + β-AgVO3
nanorods, and (E) TMB–H2O2–β-AgVO3
nanorod solution at pH 4.0 HAc–NaAc
buffer at 25ꢀC. ([TMB]: 0.1 mM, [H2O2]:
8 mM, [β-AgVO3]: 4.5 μg/mL). (b) The
β-AgVO3 naonorod-catalyzed oxidation of
diverse substrates to produce various color
reactions. (A) TMB, (B) OPD, (C) ABTS.
Inset: (a) photographs of aqueous solution of
β-AgVO3 nanorods (A), TMB + β-AgVO3
nanorods (B), TMB–H2O2 (C), H2O2 + β-
AgVO3 nanorods (D), and TMB–H2O2–β-
AgVO3 nanorods (E). (b) The corresponding
photograph of these samples.
Fig. 2. SEM images of the as-prepared β-AgVO3
nanorods.
TMB–H2O2, or H2O2+β-AgVO3 nanorod system did
not produce a typical blue color reaction. However, the
TMB–H2O2–β-AgVO3 nanorod system could produce a
color reaction. Meanwhile, two remarkable absorbance
peaks could be observed at 370 and 652 nm, which
were caused by the oxidation product of TMB. In order
to demonstrate the peroxidase-like catalytic ability of
β-AgVO3 nanorods further, two other typical peroxi-
dase substrates (OPD, ABTS) were also studied
(Figure 3(b)). These results showed that β-AgVO3
nanorods exhibited an intrinsic peroxidase-like catalytic
activity and could catalyze the oxidation of TMB in the
presence of H2O2.
intermediate radicals.28 The experimental results
showed that the absorbance gradually decreased with
increasing tert-butyl alcohol concentration from 0 to
350 mg/mL, which indicated that the peroxidase-like
activity of β-AgVO3 nanorods for catalytic oxidation of
TMB in the presence of H2O2 originates from H2O2
decomposition to generate ꢁOH radicals.
The absorbance changes of oxidized TMB at
652 nm depend on the concentration of β-AgVO3
nanorods and reaction time (Figure 4). The absorbance
gradually increased with increasing β-AgVO3 nanorod
concentration, which further confirmed that β-AgVO3
nanorods exhibited peroxidase-like ability for the cata-
lytic oxidation of TMB to produce a typical color reac-
tion. In order to prove the catalytic mechanism of
β-AgVO3 nanorods, tert-butyl alcohol was applied as a
Optimization of experimental conditions
Similar
to
nanomaterial-based
peroxidase
mimetics and the natural enzyme (HRP), the catalytic
activity of β-AgVO3 nanorods was also dependent on
the pH of the reaction buffer, incubation temperature,
and H2O2 concentration. Therefore, various pH values
(from 2.5 to 6.5), reaction temperatures (from 20 to
70ꢀC), and H2O2 concentrations (from 0.1 to
1000 mM) were investigated. At the same time, the
reaction pH, temperature, and H2O2 concentrations of
HRP were also studied under the same conditions to
compare their catalytic activity. The relative activity of
β-AgVO3 nanorods was higher in a weakly acidic
(pH 4.0–5.0) solution than in a strongly acidic or neu-
tral solution. Therefore, pH 4.0 was selected as the con-
dition for subsequent experiments. With the
.
typical OH radical capture reagent in the β-AgVO3
nanorods+TMB+ H2O2 reaction system (Figure 5).
tert-Butyl alcohol could rapidly react with OH and ter-
minate radical chain reactions by generating inert
Table 1. Elemental analysis of β-AgVO3 nanorods by ICP-
MS compared with the theoretical calculation
Ag element quality
percentage (%)
V element quality
percentage (%)
Methods
ICP-MS
Theoretical
calculation
53.93
52.17
22.88
24.64
4
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Colorimetric Sensing; Glucose Detection
reaction time up to 25 min, at which it reached a maxi-
mum. The catalytic activity of β-AgVO3 nanorods grad-
ually increased with increasing concentration of
β-AgVO3 nanorods. After the concentration reached
4.5 μg/mL, the relative activity changed very little
(Figure 6(e)). Hence, 25 min of reaction time and
4.5 μg/mL of β-AgVO3 nanorods were used for subse-
quent studies.
0 μ g/mL β -AgVO3
0.8
10 μ g/mL β -AgVO3
30 μ g/mL β -AgVO3
50 μ g/mL β-AgVO3
0.6
0.4
0.2
0.0
Kinetic analysis of β-AgVO3 nanorods as peroxidase
mimics
The catalytic activity of β-AgVO3 nanorods was
investigated under the enzyme kinetics theory and
methods using TMB and H2O2 as substrates under the
optimal conditions (Figure 7(a) and (b)). HRP was also
studied under the same conditions (Figure 7(c) and (d)).
Typical Michaelis–Menten kinetic curves of the reac-
tions were obtained by the changes of the respective
substrate concentration in the catalytic system. The
basic parameters could be calculated by using
Lineweaver–Burk equation 1/v = (Km/Vmax) × (1/[S]) +
1/Vmax (v is the initial velocity, Km is the Michaelis con-
stant, Vmax is the maximum reaction velocity, and [S] is
the concentration of the substrate). The Michaelis–
Menten constant (Km) and the maximum initial velocity
(Vmax) of β-AgVO3 nanorod peroxidase mimics and
HRP are listed in Table 2. Km is a measure of the
enzyme affinity for a substrate. A smaller value of Km
indicates a stronger affinity between the enzyme and the
substrate, and a more efficient catalysis. It could be seen
that the Km value of β-AgVO3 nanorods with TMB as
the substrate was lower than that of HRP and AgVO3
nanobelts, which suggested that the β-AgVO3 nanorods
had higher affinity to TMB than HRP and AgVO3
nanobelts.
0
50
100
150
200
250
300
350
Time (s)
Fig. 4. Absorbance change at 652 nm versus time in
the presence of 0 μg/mL (black), 10 μg/mL
(red), 30 μg/mL (blue), and 50 μg/mL (green)
β-AgVO3 nanorods in the HAc–NaAc buffer
(pH 4.0, 0.2 M) at room temperature.
temperature increasing from 20 to 70ꢀC, the catalytic
activity of β-AgVO3 nanorods first increased and then
decreased. Hence, room temperature (25ꢀC) was taken
as the optimum temperature. The optimal H2O2 con-
centration was found to be 8 mM. There values were
very similar to those of HRP (Figure 6(a)–(c)). In addi-
tion, the effects of reaction time and concentration on
the catalytic activity of β-AgVO3 nanorods were also
investigated. As shown in Figure 6(d), the relative activ-
ity of β-AgVO3 nanorods gradually increased until
350 mg/mL
1.2
300 mg/mL
250 mg/mL
1.0
200 mg/mL
100 mg/mL
0.8
Determination of glucose
0 mg/mL
Under the optimum conditions, a simple colori-
metric determination method of glucose was developed
combined with GOx. H2O2 could be produced by GOx
catalytic oxidation of glucose solution; then ꢁOH gener-
ated by H2O2 decomposed. Finally, β-AgVO3 nanorods
could effect catalytic oxidation of TMB and produce a
typical color reaction in the presence of H2O2. Based
on this phenomenon, the changes of the absorbance at
652 nm with various concentrations of glucose were
investigated. As shown in Figure 8(a), the color of the
0.6
0.4
0.2
500
600
700
Wavelength (nm)
Fig. 5. Effect of different concentrations of tert-butyl
alcohol on the oxidation of TMB.
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Article
Lu et al.
a
b
b
d
β
-AgVO3
a
β
-AgVO3
0.0045
0.0036
0.0027
0.0018
120
HRP
β-AgVO3
0.0032
0.0024
0.0016
HPR
β-AgVO3
750
600
450
300
80
40
0
800
80
40
0
600
400
0.00
0.15
1/C
0.30
(mM
0.45
0.000
0.015
1/C
0.030
0.045
-1)
H2O2
(μ M)
TMB
0
15
30
CH (mM)
45
0
100
200
300
CTMB (μM)
2
O
2
20
30
40
50
60
70
2
3
4
5
6
7
pH
Temperature (°C)
c
d
HRP
c
HRP
0.0045
0.0030
0.0015
0.0018
0.0012
0.0006
100
80
60
40
20
0
2000
1500
1000
HRP
β-AgVO3
1.2
0.8
0.4
0.0
1200
900
600
300
500
0
1
2
3
4
5
-1)
(mM
H O2
2
0.015
0.030
TMB
0.045
1/C
1/C
(μ M)
0
2
4
6
8
0
80
160
CTMB (μM)
240
CH (mM)
O
2 2
0
200 400 600 800 1000
[H2O2] (mM)
0
8
16
24
32
Time (min)
Fig. 7. Steady-state kinetic analyses using Michaelis–
Menten model and Lineweaver–Burk model
(insets) for β-AgVO3 nanorods and by (a,c)
varying the concentration of TMB with fixed
H2O2 concentration and (b,d) varying the
concentration of H2O2 with fixed TMB
concentration.
e
100
80
60
40
20
01
2
3
4
5
[β-AgVO3] (μg/mL)
substances. As shown in Figure 9, these coexisting sub-
stances did not influence the detection of glucose and
revealed the high selectivity of the β-AgVO3 nanorods–
TMB–H2O2 system for glucose detection. Thus, this
system can be applied to glucose determination in real
samples.
Fig. 6. Effect of pH (a), temperature (b), H2O2 con-
centration (c), reaction time (d), and
β-AgVO3 concentrations (e) on the catalytic
reaction.
In order to verify the feasibility of the proposed
colorimetric method, experiments using five human
serum samples were conducted. The diluted serum sam-
ple solutions were detected under the same conditions
as the standard for glucose determination. As can be
seen, the results of the proposed colorimetric method
solution changed deeper and deeper; at the same time,
the absorbance at 652 nm increased gradually when the
concentration of glucose ranged from 1.25 to 80 μM. A
good linear relationship was found between the absorb-
ance and the concentration of glucose from 1.25 to
60 μM (R2 = 0.995) (Figure 8(b)), and the limit of
detection of glucose was estimated to be 0.5 μM. When
compared with other nanomaterial-based colorimetric
sensors, the detection limit of the proposed colorimetric
method is also comparable (Table 3). In addition, the
proposed detection limit was evaluated by the formula
S/N = ((averagesample – averageblank)/SDblank). And the
sample concentration consistent with 3 < S/N < 5 was
defined as the limit of detection.33
Table 2. Comparison the Michaelis–Menten constant (Km)
and the maximum reaction rate (Vmax) of β-AgVO3
nanorods with HRP and AgVO3 nanobelts
Km
Vmax
Catalyst
Substance [mM]
[10−4 s−1
]
β-AgVO3
TMB
H2O2
TMB
H2O2
TMB
H2O2
0.04118
37.97
53.09
104.01
25.65
—
nanorods
5.291
0.2422
1.018
8.03
HRP
Selectivity of the method
The selectivity for the detection of glucose was
studied. The experiments, under the same conditions,
were conducted to study the effects of the other foreign
AgVO3
nanobelts26
14
—
6
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JOURNAL OF THE CHINESE
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Colorimetric Sensing; Glucose Detection
Table 3. Comparison of various nanomaterial-based
colorimetric sensing for glucose determination
a
[glucose]
Linear
range
(μM)
Detection
limit
(μM)
0.3
0.2
0.1
80 μm
0 μm
Catalyst
References
15
29
30
Ag nanoparticles
Ceria nanoparticles
Co3O4/rGO
nanocomposites
H2TCPP – Fe3O4
Pt–DNA complexes
β-AgVO3 nanorods
5–200
6.6–130
1–100
0.1
3
1
31
32
5–25
0.1–1000
1.25–80
2.21
0.1
0.5
This work
550
600
650
700
750
Wavelength (nm)
CONCLUSION
In summary, β-AgVO3 nanorods were shown to
possess intrinsic peroxidase-like activity. The β-AgVO3
nanorods could catalyze the oxidation of several sub-
strates and generate a typical color reaction in the pres-
ence of H2O2. With O2, GOx could catalyze the
oxidation of glucose and then produce H2O2. The
β-AgVO3 nanorods had a higher affinity to TMB and a
lower affinity to H2O2 compared to HRP. A simple,
cheap, and selective colorimetric method was developed
for glucose detection based on the above principles. In
addition, this method was also tested in the detection of
glucose in human serum samples. Furthermore, this
b
0.2
0.1
0.0
y=0.00771+0.00354x
0.2
0.1
0.0
2
R =0.995
0
15 30 45 60
The concentration of glucose (μM)
0
20
40
60
80
The concentration of glucose (μM)
Fig. 8. (a) Effect of glucose on the absorption spectra
in the GOx–β-AgVO3 nanorods–TMB sys-
tem. (b) Curve of glucose detection from
100
75
50
25
0
1.25 to 80 μM, where ΔA = A(glucose,652nm)
−
A(blank,652nm). Inset: (a) Color changes of the
GOx–β-AgVO3 nanorod–TMB system with
different concentrations of glucose (from left
to right: 0 to 80 μM), (b) Line calibration plot
of the glucose determination.
were similar to those using the hospital’s assay kit
(Table 4). In addition, to demonstrate the reliability
and precision of this colorimetric method further, the
spiked recoveries of glucose in two serum samples were
studied, and the results are listed in Table 5. The recov-
ery values of these two serum samples range from 99.40
to 105.45%. These results show that the colorimetric
method based on the peroxidase-like catalytic ability of
β-AgVO3 nanorods can applied to detect glucose in real
samples.
Fig. 9. Selectivity of the test using GOx and β-AgVO3
nanorods for the determination of glucose.
Insert: the corresponding color change of dif-
ferent samples. The concentrations of glucose
and the other coexisting substances are 60 and
600 μM, respectively.
J. Chin. Chem. Soc. 2017
© 2017 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.jccs.wiley-vch.de
7

Article
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Table 4. Results of glucose detection in the real serum
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(mM, n = 3)
Glucose assay
kit (mM)
1
2
3
4
5
13.16 ꢂ 0.045
10.46 ꢂ 0.040
8.74 ꢂ 0.089
12.62 ꢂ 0.078
8.36 ꢂ 0.15
13.27
11.15
9.34
13.30
9.50
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RSD
Original
amount (μM)
Added
(μM)
Found
(μM)
Recovery
(%)
(%,
n = 3)
13.16
5
20
40
5
20
40
18.35
34.25
54.80
15.43
30.85
52.06
103.80
105.45
104.10
99.40
101.95
104.00
1.41
1.35
0.46
0.39
1.42
2.03
10.46
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This work was supported by the Guangxi Natural
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Science
Foundation
of
China
(Nos.
2014GXNSFBA118045, 2014GXNSFBA118062 and
2015GXNSFAA139030), the scientific research project
of Hechi University (No. XJ2015ZD004), and the scien-
tific research project of the education department of
Guangxi Zhuang Autonomous Region (Nos.
YB2014331 and ZD2014113).
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