Direct electrochemistry and electrocatalysis of myoglobin immobilized in hyaluronic acid and room temperature ionic liquids composite film

A novel biocomposite film based on hyaluronic acid (HA) and hydrophilic room temperature ionic liquid 1-ethyl-3-methyl-imidazolium tetrafluoroborate ([EMIM][BF4]) was explored. Here, HA was used as a binder to form [EMIM][BF4]-HA composite film and help [EMIM][BF4] to attaching on glass carbon electrode (GCE) surface, while doping [EMIM][BF4] in HA can effectively reduce the electron transfer resistance of HA. The composite film can be readily used as an immobilization matrix to entrap myoglobin (Mb). A pair of well-defined and quasi-reversible redox peaks of Mb was obtained at the Mb-[EMIM][BF4]-HA composite film modified GCE (Mb-[EMIM][BF4]-HA/GCE) through direct electron transfer between Mb and the underlying electrode. The Mb-[EMIM][BF4]-HA/GCE showed an excellent electrocatalytic activity toward the reduction of H2O2. Based on the [EMIM][BF4]-HA biocomposite film, a third-generation reagentless biosensor could be constructed for the determination of H2O2.