Electronic Supplementary Material
Colorimetric determination of melamine based on the reversal of the mercury(II)
induced inhibition of the light-triggered oxidase-like activity of gold nanoclusters
Gen-Xia Cao, Xiu-Ming Wu, Yu-Ming Dong, Zai-Jun Li, Guang-Li Wang*
The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education,
School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, P.
R. China
* Corresponding author. Tel.: +86 510 85917090; Fax: +86 510 85917763.
E-mail address: glwang@jiangnan.edu.cn. (G. L.Wang)
1
0.4
Abs(a.u.)
0.3
0.2
0.1
0.0
300
400
500
600
Wavelength(nm)
700
Fig. S1 The oxidation of TMB by 0.1 mg·mL-1 HRP under visible light irradiation.
Inset image is the corresponding colour of the solution
Absorbance(a.u.)
0.5
0.4
0.3
a
0.2
b
0.1
0.0
400
500
600
700
Wavelength(nm)
800
Fig. S2 The oxidation of TMB was conducted with air saturated solution (a), and after
bubbling the solution with high purity nitrogen to remove dissolved oxygen for
twenty minutes (b)
2
B
A
HRP-AuNCs
HRP
100
HRP-AuNCs
HRP
80
Relative Activity
Relative Activity(%)
100
60
40
20
0
80
60
40
20
0
20
0
100
80
60
40
Temperature(℃)
10
8
6
pH
4
2
Fig. S3 The relative catalytic activities of HRP-Au NCs under visible light irradiation
for ten minutes ( ) and HRP using 5 mmol·L-1 H2O2 as an oxidant ( ) at different
temperature (a) and solution pH (b). Reaction conditions: 500 µmol·L-1 TMB, 30 μL
HRP-Au NCs, irradiation time: 10 min
B
Off
20
-10.0 nA
Current(μA)
On
Photocurrent(nA)
A
15
10
5
0
-5
-10
-15
0
10
20
30
40
50
60
-1.5
Time(s)
-1.0
-0.5
0.0
0.5
1.0
1.5
Potential/V
Fig. S4 (A) Photocurrent-time performances of HRP-Au NCs modified electrodes in
0.1 mol·L-1 Na2SO4 aqueous solutions under visible light irradiation (λ≥ 400 nm). (B)
Cyclic voltammogram (CV) of HRP-Au NCs (scan rate: 100 mV·s-1, at room
temperature)
3
0.6
Absorbance(a.u.)
0.5
0.4
0.3
c
0.2
0.1
b
a
0.0
250
300
350
Wavelength(nm)
400
Fig. S5 (a) UV−vis spectra of Hg2+, (b) melamine, and (c) the mixture of Hg2+ and
melamine in aqueous solution
Table S1 Comparison of some existing methods for the determination of melamine
Method
Linear range
（μmol·L-1）
Detection limit
（μmol·L-1）
Reference
Fluorescence method
7.93-47.6
6.35
Nascimento et al. [1]
Fluorescence method
0.15-20
0.12
Li et al. [2]
Fluorescence method
1.59-630
0.951
Zeng et al. [3]
Flight mass spectrometry
0.793-79.3
0.793
Su et al. [4]
HPLC
6.34-634
0.634
Wen et al. [5]
Colorimetric method
0.2-24
0.08
Wang et al. [6]
Colorimetric method
7.94-1590
7.94
Liang et al. [7]
Colorimetric method
0.2-15
0.072
This work
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