A biorecognition system for concanavalin a using a glassy carbon electrode modified with silver nanoparticles, dextran and glucose oxidase

Concanavalin A (Con A) was chosen as a model lectin protein for an electrochemical study on the interaction between lectins and carbohydrates. A composite prepared from reduced graphene oxide and silver nanoparticles (rGO-AgNPs) acted as a redox probe, and phenoxy-derivatized dextran (DexP) and glucose oxidase (GOx) acted as recognition elements. The rGO-AgNPs, DexP and GOx were deposited on the surface of a glassy carbon electrode. The immobilized DexP and GOx showed high affinity for the target lectin Con A. The surface-modified biosensor was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, UV-vis absorption spectra, cyclic voltammetry and electrochemical impedance spectroscopy. Due to the high affinity of Con A for both DexP and GOx, the biosensor displays a detection limit for Con A that is as low as 0.67 ng mL(-1) at a working voltage of 48 mV. The response is linear in the 2.0-322 ng mL(-1) concentration range, thus offering a sensitive means for the determination of Con A.