Electronic Supplementary Material
A disposable electrochemical immunosensor for myeloperoxidase based on a
indium tin oxide electrode modified with a ionic liquid composite film
composed of gold nanoparticles, poly(o-phenylenediamine) and carbon
nanotubes
Bei Liu·Lingsong Lu·Qiong Li·Guoming Xie *
Key Laboratory of Medical Diagnostics of Ministry of Education，Department of
Laboratory Medicine, Chongqing Medical University, Chongqing 400016, P. R.
China.
*Corresponding author: Tel: +86 23 68485388, Fax: +86 23 68485005,
E-mail:guomingxie@cqmu.edu.cn
Optimization of experimental parameters
Effect of pH of the working buffer
The immunosensor performance was studied in 0.1M PBS with the pH value between
5.0 and 8.0. The results are shown in Fig. S1. As can be seen, the change of peak
currents (ΔI) before and after being incubated with MPO antigen increased with the
increase of the solution pH from 5.0 to 7.0 and reached to the maximum, then
decreased when the pH value of the solution further increases. So pH 7.0 was chosen
throughout the experiments.
Influence of incubation temperature and time
Incubation temperature may have effect on the activity and reaction rate of antibody
and antigen. Fig. S2 reveals the influence of incubation temperature in the range of
20-45°C on the behavior of the immunosensor. As shown in Fig. S2, the
1
immunosensor exhibited a maximum value of ΔI at 35°C. Therefore, we used the
optimized incubation temperature of 35°C for further analysis.
Incubation time also influenced the behavior of the electrochemical
immunosensors. The effect of the incubation time on the peak current of the
immunosensor was investigated from 6 to 25 minutes. Seen from Fig. S3, the current
decreased with the increase of incubation time, and came to the minimum current at
20 min, and then longer incubation time could not reduce the response. As a result, 20
min of incubation time was employed for the detection of MPO.
20
ΔI/μA
15
10
5
0
5.0
5.5
6.0
6.5
7.0
7.5
8.0
pH
Fig. S1 Influence of pH on the current response of the immunosensor after being
incubated with 50 ng.mL-1 MPO in 0.1 M PBS (pH 7.0) containing 1 mM
[Fe(CN)6]3-/4- and 0.1 M KCl at 50 mV.s-1
19
18
17
ΔI/μA
16
15
14
13
12
11
10
20
25
30
35
40
45
T/℃
Fig. S2 Influence of incubation tempreture on the current response of the
immunosensor after being incubated with 50 ng.mL-1 MPO in 0.1 M PBS (pH 7.0)
containing 1 mM [Fe(CN) 6]3-/4- and 0.1 M KCl at 50 mV.s-1
2
100
95
I/μA
90
85
80
75
70
65
5
10
15
20
25
t/min
Fig. S3 Influence of incubation time on the current response of the immunosensor
after being incubated with 50 ng.mL-1 MPO in 0.1 M PBS (pH 7.0) containing 1 mM
[Fe(CN)6]3-/4- and 0.1 M KCl at 50 mV.s-1
3