Perylene derivative and persulfate as highly efficient electrochemical system for constructing sensitive amperometric aptasensor.

To design highly efficient electrochemistry system was important for construct simple and sensitive biosensors, which was crucial in clinical diagnosis and therapy. In this work, a novel electrochemistry probe N,N'-di (1-hydroxyethyl dimethylaminoethyl) perylene diimide (HDPDI) with positive charges was reported to show two-electron redox behavior in neutral phosphate buffer solution between 0 and -1.0 V. And K ₂ S ₂ O ₈ in solution could significantly increase the reduction current of HDPDI at -0.29 V, which was interpreted with cyclic catalysis mechanism of K ₂ S ₂ O ₈ . Moreover, HDPDI as electrochemical probe and K ₂ S ₂ O ₈ as signal enhancer was used to design aptasensors for protein detection. Thrombin was used as target model protein. Thiolate ssDNA with thrombin-binding sequence was immobilized on gold electrode to selectively capture thrombin and adsorb HDPDI. The thiolate ssDNA without binding with thrombin was with random coil structure and could adsorb HDPDI through electrostatic attraction interaction. However, the thiolate ssDNA binding with thrombin became G-quadruplex structure and hardly adsorbed HDPDI. Thus, with increasing the concentration of thrombin, the current signal stepwisely decreased and was taken as detection signal. Compared with other aptasensors based on electrochemistry molecules without signal enhancer, the proposed aptasensors exhibited wider linear response for thrombin between 1 pg mL ^-1 and 100 ng mL ^-1 with lower detection limit 0.13 pg mL ^-1 . In addition, the proposed aptasensor showed good feasibility in human serum samples.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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