Bioelectrocatalytic and biosensing properties of horseradish peroxidase covalently immobilized on (3-aminopropyl)trimethoxysilane-modified titanate nanotubes

摘要

Titanate nanotubes (TiNT) surface modified with (3-aminopropyl)trimethoxysilane were employed as a support for covalent immobilization of horseradish peroxidase (HRP) by using 1,4-benzoquinone as a coupling agent. Composite film-electrodes consisting of HRP-modified TiNT embedded into the porous carbon powder/Nafion matrix were fabricated and their applicability in direct bioelectrocatalytic reduction of H_2O_2 and H_2O_2 biosensing were investigated. An efficient direct electron transfer between the immobilized HRP molecules and the electrode was observed in the presence of H_2O_2 at potentials lower than 600mV (vs. Hg/Hg_2Cl_2/3.5 M KCl). For the HRP-TiNT-modified electrodes polarized at 0 mV, a linear dependence of the bioelectrocatalytic current on the concentration of H_2O_2 was observed up to the concentration of H_2O_2 equal to 10 μM, with the sensitivity of (1.10 ± 0.01) AM~(-1) cm~(-2) and the detection limit of 35 nM.