Direct electrochemistry and electrocatalysis of myoglobin based on silica-coated gold nanorods/room temperature ionic liquid/silica sol–gel composite film

Abstract

A novel biosensor based on the silica-coated gold nanorods (GNRs@SiO 2) and hydrophilic room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium tetrafluroborate ([bmim][BF 4]) was fabricated for the determination of hydrogen peroxide (H 2O 2) and nitrite. GNRs@SiO 2 can not only act as a binder to hinder [bmim][BF 4] (RTIL) leaking from the electrode surface, but also provide a favorable microenvironment for direct electrochemistry of myoglobin (Mb). A pair of well-defined and quasi-reversible redox peaks of Mb was obtained at the GNRs@SiO 2–Mb/RTIL–sol–gel composite film modified GCE (GNRs@SiO 2–Mb/RTIL–sol–gel/GCE) through direct electron transfer between Mb and the underlying electrode. This biosensor showed an excellent electrocatalytic activity towards hydrogen peroxide and nitrite. The linear range for the determination of H 2O 2 was from 0.2 to 180 μM with a detection limit of 0.12 μM based on the signal-to-noise ratio of 3. In addition, the biosensor also exhibited high selectivity, good reproducibility, and long-term stability. Therefore, this kind of composite film can provide an ideal matrix for protein immobilization and biosensor fabrication.