Crystal violet as an i-motif structure probe for reversible and label-free pH-driven electrochemical switch.
A simple pH-induced electrochemical switch based on an i-motif structure is developed by using crystal violet as a selective electrochemical probe for the i-motif structure. Thiol-modified cytosine-rich single-strand oligonucleotide (C-rich ssDNA) can be self-assembled on the gold electrode surface via gold-sulfur interaction. Crystal violet is employed as an electrochemical probe for the i-motif structure because of its capability of binding with the i-motif structure through an end-stacking mode. In acidic aqueous solution, crystal violet may approach the electrode surface owing to the formation of the i-motif structure, resulting in an obvious signal, so-called "ON" state. Whereas in neutral or basic aqueous solution, the i-motif structure unfolds to dissociative single strand, which causes crystal violet to leave from the electrode surface, and a weak signal is obtained, so-called "OFF" state. In addition, in the range of pH 4.6-7.3, the increase in current has a good linear relationship (R=0.989) with pH value in the testing solutions. This pH-driven electrochemical switch has the advantages of simplicity, sensitivity, high selectivity, and good reversibility. Furthermore, it provides a possible platform for pH measurement.
Key Laboratory of Eco-environments in Three Gorges Reservoir Region (Ministry of Education), School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China.
Xi Yuan
XY
Zhang
Key Laboratory of Eco-environments in Three Gorges Reservoir Region (Ministry of Education), School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China. Electronic address: luohq@swu.edu.cn.
Hong Qun
HQ
Luo
Key Laboratory of Eco-environments in Three Gorges Reservoir Region (Ministry of Education), School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China. Electronic address: linb@swu.edu.cn.
Nian Bing
NB
Li
D002021:Buffers; D003596:Cytosine / Q000737:chemistry; D004277:DNA, Single-Stranded / Q000737:chemistry*; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods*; D005840:Gentian Violet / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D009690:Nucleic Acid Conformation; D013997:Time Factors
D002021:Buffers; D004277:DNA, Single-Stranded; D003596:Cytosine; D005840:Gentian Violet
Crystal violet; Electrochemical switch; i-Motif structure; pH