“On-off” switchable electrochemical affinity nanobiosensor based on graphene oxide for ultrasensitive glucose sensing

► A “smart” pH-switchable electrochemical glucose nanobiosensor ConA-DexP/GO is designed by employing the glucose-ConA-dextran competitive system on a GO-based sensing platform. ► Upon addition of glucose to the ConA-DexP/GO sensing surface, the interfacial electron transfer kinetics between the redox probe and the electrode is enhanced due to the displacement-induced charge evolution of the platform, making the sensor from “off” state to “on” state simultaneously. ► This ultrasensitive glucose nanobiosensor had a broad linearity over a range of 5.0 μM-9.0 mM with a detection limit as low as 0.34 μM and performed excellent selectivity for glucose over other sugars. ► This novel sensing strategy is promising for the preparation of high performance biosensors for other small molecules.