Direct electrochemistry and electrocatalysis of horseradish peroxidase with hyaluronic acid–ionic liquid–cadmium sulfide nanorod composite material

A new composite material consisted of hyaluronic acid (HA), ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) and cadmium sulfide (CdS) nanorod was fabricated and used for the immobilization of horseradish peroxidase (HRP) on the surface of a carbon ionic liquid electrode (CILE), which was prepared with 1-ethyl-3-methyl-imidazolium ethylsulphate ([EMIM]EtOSO3) as modifier. Spectroscopic results indicated that HRP remained its native structure in the composite film. Based on the synergistic effect of the materials used, an obvious promotion to the direct electron transfer efficient between HRP and CILE was achieved with a pair of well-defined redox peaks appeared in 0.1 mol L−1 phosphate buffer solution, indicating the realization of the direct electrochemistry of HRP. The immobilized HRP showed good electrocatalytic activity towards the reduction of trichloroacetic acid and H2O2 with the electrochemical parameters calculated. Based on the fabricated electrode, a new third-generation electrochemical biosensor was constructed with good stability and reproducibility.