Colorimetric aptasensor for fumonisin B1 detection by regulating the amount of bubbles in closed bipolar platform

Abstract

A novel electrochromic biosensor has been developed by coupling the chemical sensing reactions at closed bipolar electrode (BPE) to the electrochemical reactions at the driving electrode for colorimetric detection of fumonisin B1 (FB1). Here, BPE is not only served as the sensing electrode, but also acted as a vital bridge to form electric connection between sensing and reporting solution. The conductive bridge was formed by connecting glassy carbon electrode (GCE) in sensing cell to Pt wire in reporting cell with electric wire. In order to achieve FB1 detection, a recognition probe was prepared by conjugating Au nanoparticles (NPs) labeled FB1 aptamer to capture DNA-Fe3O4 NPs surface. After the chemical reduction of silver ion on Au NPs, the prepared probes were introduced to GCE surface to catalyze the decomposition of H2O2 to oxygen bubbles by silver particles. The accumulation of numerous bubbles led to a significant decrement of the effective area of GCE cathode and current flow through the electric bridge which was reported by the inhibited electro-deposition of Prussian blue (PB) at ITO driving electrode in sensing cell. After adding FB1, Au NPs –aptamer was liberated from Fe3O4 NPs –capture DNA surface, resulting in a decreased amount of silver particles assembled on GCE and an increased amount of PB deposited at ITO electrode. This indirect colorimetric strategy provides a simple and portable for bioanalysis.