Electrochemical myoglobin biosensor based on graphene–ionic liquid–chitosan bionanocomposites: Direct electrochemistry and electrocatalysis

A novel biocompatible sensing strategy based on a graphene (GR), ionic liquid (IL) 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4) and chitosan (CTS) composite film for the immobilization of myoglobin (Mb) was adopted in this paper. The UV–vis and FT-IR spectroscopic results demonstrate that the Mb in the composite film maintained its native structure. The direct electron transfer properties and the bioelectrocatalytic activity of the Mb in the nanocomposite film were further investigated. The cyclic voltammetric results indicate that a pair of quasi-reversible redox waves appeared, thereby signifying that the direct electrochemistry of the Mb was realized in the nanocomposite film. This result can be attributed to the specific properties of the material used, including the large surface-to-volume ratio and high conductivity of the GR, the high ionic conductivity of the IL, the interaction of the IL with the GR, and the high biocompatibility of the CTS, which enhanced the absorption of the Mb and promoted the direct electron transfer between the Mb and the substrate electrode. The CTS–Mb–GR–IL modified electrode exhibited a high electrochemical catalytic ability to reduce trichloroacetic acid, which demonstrates the material's potential application in third-generation biosensor.