An RNA aptamer-based electrochemical biosensor for sensitive detection of malachite green

Abstract

An RNA aptamer-based electrochemical biosensing strategy has been developed for sensitive and selective detection of malachite green (MG). This biosensor is fabricated by the self-assembly of a thiolated MG aptamer (MGA) on AuNPs/graphene–chitosan nanocomposite modified glass carbon electrode. In addition, a short alkanethiol is further assembled on the AuNPs surface to generate uniform packing and reduce nonspecific adsorption. When the modified electrode is incubated in the presence of MG, MGA combines specifically with MG, which causes the horseradish peroxidase (HRP)-labelled MG antibody close to the electrode surfaces. As a result, MG detection is realized by outputting a redox current from electro-reduction of the hydrogen peroxide reaction catalyzed by HRP. Differential pulse voltammetry (DPV) is performed to record the signal responses. The results reveal the biosensor displays a very low detection limit as low as 16.3 pg mL⁻¹ and a wide linear range from 1 × 10⁻⁴ to 10 μg mL⁻¹ of MG. Hence, this proposed RNA aptamer-based electrochemical strategy may offer a simple, rapid, cost-effective, highly selective and sensitive method for the quantification of MG.