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i-Motif based pH induced electrochemical switches

2012; Elsevier BV; Volume: 24; Linguagem: Inglês

10.1016/j.elecom.2012.06.039

1873-1902

Xiaoyao Gao, Xianghui Li, Wenming Xiong, Huiming Huang, Zhenyu Lin, Bin Qiu, Guonan Chen,

DNA and Nucleic Acid Chemistry

Abstract Two C-rich DNA strands are employed to fabricate the intermolecular i-switch: strand 1 with thiol at the 5′-terminus immobilized on the gold electrode through the thiol–Au interaction, and ferrocene (Fc)-labeled strand 2 that hybridizes with strand 1 to form an i-switch nanostructure. In neutral or basic aqueous solution, the i-switch is present in the form of an extended duplex that makes Fc far away from the electrode; a weak faradaic current is obtained, so-called “OFF” state. While in the slight acidic condition, an obvious signal is detected from Fc which approaches the electrode due to the formation of the i-motif, so‐called “ON” state. The faradaic current has a linear relationship with the pH value in the range of 5.8–8.0.