Electrodeposited Graphene and Silver Nanoparticles Modified Electrode for Direct Electrochemistry and Electrocatalysis of Hemoglobin

By using a 1-butylpyridinium hexafluorophosphate based carbon ionic liquid electrode (CILE) as the working electrode, graphene (GR) nanosheets and silver nanoparticles (Ag NPs) were step by step electrodeposited on the surface of the CILE with potentiostatic method. The fabricated Ag/GR/CILE was used as a new platform for protein electrochemistry and hemoglobin (Hb) was immobilized on its surface with chitosan (CTS) as film forming material. In 0.1 mol/L phosphate buffer solution, a pair of well-defined and quasi-reversible redox peaks appeared on the CTS/Hb/Ag/GR/CILE with a formal peak potential of 0.202 V (vs. SCE) and a peak-to-peak separation (DEp) of 68 mV, which indicated that direct electrochemistry of Hb was realized on the modified electrode. The results could be attributed to the synergistic effects of Ag NPs and GR nanosheets on the electrode surface, which provided a specific three-dimensional structure with high conductivity and good biocompatibility. The Hb modified electrode showed excellent electrocatalysis to the reduction of trichloroacetic acid in the concentration range from 0.8 to 22.0 mmol/L with a detection limit of 0.42 mmol/L (3s). Moreover, the modified electrode exhibited favorable reproducibility, long term stability and accuracy, with potential applications in the third-generation electrochemical biosensor.