Electrodeposition of Co Nanoparticles on the Carbon Ionic Liquid Electrode as a Platform for Myoglobin Electrochemical Biosensor

The electrochemical deposition of Co nanoparticles on carbon ionic liquid electrode (CILE) was described and further used as the platform to construct a myoglobin (Mb) electrochemical biosensor. CILE was prepared by mixing a certain ratio of carbon powder, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4), and liquid paraffin together. The presence of ionic liquid on the electrode surface facilitated the formation of Co nanoparticles, and a layer of Co nanoparticles was deposited on the surface of CILE with the average diameter of 300 nm after the cyclic voltammetic scan in the CoCl2 solution. The formed Co/CILE was used as a new basal electrode for the investigation on the direct electrochemistry of protein. Mb molecules were further cast on the surface of Co/CILE and immobilized with Nafion film. The fabricated Nafion/Mb/Co/CILE showed good electrochemical behaviors with a pair of well-defined quasi-reversible redox peaks of Mb obtained, which was attributed to the electrochemical reaction of heme Fe(III)/Fe(II) redox couples. The results indicated that the presence of Co nanoparticles exhibited great promotion to the direct electron transfer of Mb. The Mb electrochemical biosensor showed good electrocatalytic activity to the reduction of hydrogen peroxide and trichloroacetic acid (TCA). The modified electrodes showed good stability and reproducibility, which had potential application in third generation biosensor.