Construction of a Concanavalin A electrochemical sensor base on a novel sandwich capture mode

- A novel sandwich configuration was introduced for determination of ConA.
- Chitosan functionalize graphene oxide was used as a substrate for immobilizing D-mannose.
- An electrochemical sensor with enzyme amplification effect was established with an excellent analytical performance.
- Ultratrace amount of ConA in nM level can be determined.

Herein, a concanavalin A (ConA) electrochemical sensor was constructed via a sandwich mode. Firstly chitosan functionalized graphene oxide (CS/GO) composite was introduced on the of glassy carbon electrode (GCE) as the substrate. D-mannose (D-man) was immobilized on the surface of CS/GO via Schiff base reaction. Due to the specific affinity between mannose and ConA, the prepared D-man/CS/GO sensing interface could specifically capture ConA which could further react with mannose residues of HRP and form a sandwich configuration. Based on the catalytic effect of horseradish peroxidase (HRP) to H2O2, a ConA electrochemical sensor with enzyme catalytic amplification was constructed by taking hydroquinone as electrical mediator. The morphology of CS/GO was investigated by transmission electron microscope and Fourier transform infrared spectroscopy. Electrochemical techniques including electrochemical impedance spectroscopy and differential pulse voltammogram (DPV) were used for reveal the characteristics of the sensing platform. Benefit from the high surface area of GO and enzyme catalytic amplification of HRP, the peak current from DPV is linearly dependent on the ConA concentration ranging from 5 × 10−9 to 5 × 10−7 mol/L with a detection limit of 1.24 × 10−9 mol/L. The results demonstrated that the proposed sensor might exploit a new direction for determination of ConA.

An electrochemical sensor with enzyme amplification effect was established for nM level ConA determination by immobilizing D-mannose chitosan on functionalize graphene oxide and then capture ConA to react with mannose residues of HRP to form a sandwich configuration.142