Conformational switch for cisplatin with hemin/G-quadruplex DNAzyme supersandwich structure

Cisplatin is a representative of cytotoxic and antineoplastic metallodrugs used for the treatment of various malignancies. In this paper, an enzyme-free amplification platform involving an autonomous target triggered process that yields the formation of the hemin/G-quadruplex DNAzyme wires was designed for the detection of cisplatin. Given the virtue of hemin/G-quadruplex DNAzyme wires (supersandwich DNAzyme structure) containing many units of hemin/G-quadruplex DNAzyme, an amplified electrochemical signal was achieved. Based on the combination of cisplatin with the guanine of the designed hemin/G-quadruplex DNAzyme supersandwich DNA structure, changing this structure and decreasing its catalytic effect on H2O2, it was used for the study on the analysis of cisplatin. With the concentration of the cisplatin increasing, the conformational change of the supersandwich DNA structure changed gradually. Then a relationship between the concentration of the cisplatin and the obtained electrochemical signal can be established. The detection concentration range of cisplatin was from 0.05 to 5 mu M with a low detection limit of 20 nM using a signal three-fold the background noise and the correlation coefficient is 0.9993. The proposed approach is able to provide unique opportunities as simplicity in design and easy operations. Therefore, the proposed sensor presents remarkably high sensitivity and selectivity. (C) 2013 Elsevier B.V. All rights reserved.