Electronic Supplementary Material
Enzyme-free electrochemical detection of microRNA via target-triggered
hybridization chain reaction amplification strategy
Hongying Liua,b*, Xiaoqiong Beia, Qiuting Xiaa, Yan Fua, Shi Zhanga, Maochuan Liua,
Kai Fana, Mingzhen Zhanga, Yong Yanga
a
College of Life Information Science & Instrument Engineering, Hangzhou Dianzi
University, Hangzhou 310018, China
b
State Key Lab of Analytical Chemistry for Life Science, Key Lab of Mesoscopic
Chemistry of the MOE, and School of Chemistry and Chemical Engineering, Nanjing
University, Nanjing 210093, China
*Corresponding author (H. Y. Liu), Tel & Fax: +86-571-87713533, E-mail address:
liuhongying@hdu.edu.cn
Optimization of the method
Some parameters such as addition of TCEP, time for DNA incubation, temperature
for DNA incubation, and concentration of DNA were optimized. At first, comparison
of the resistance with or without TCEP is shown in Figure S1A. As we predicted, in
the presence of TCEP, the resistance is 6 times larger than that in the absence of TECP,
confirming the activation of TCEP. Then, the effect of incubation time on the
resistance was investigated. As seen from Figure 1B, the largest value is achieved at
12 h among different incubation time. Thus, 12 h was selected as the best incubation
time. In addition, the effect of incubation temperature on the resistance was
investigated. In Figure 1C, a significant increase of peak current is observed between
4 and 37 °C. Further increasing will destroy the properties of DNA. Therefore, 37 °C
was used for the following experiment. The concentration of DNA also influenced the
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loading of DNA. To optimize the concentration of DNA, we recorded the resistance
with a series of different concentration of DNA. As shown in Figure 1D, the value
increased gradually with the concentration of DNA and then leveled off after 1 µM.
Thus, 1 µM was selected as the optimized concentration of DNA.
Figure S1. Effects of (A) TCEP, (B) incubation time of DNA, (C) temperature, and (D)
concentration of DNA on the normalized electrochemical signal.
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