RESUMO
Hierarchical porous titanium dioxide (hp-TiO2) was prepared using natural magnolia grandiflora petals as templates and was further employed for the immobilization of horseradish peroxidase (HRP). Scanning electron microscopy (SEM) and nitrogen adsorption-desorption measurement revealed the wrinkled and porous structure of the obtained hp-TiO2. Fourier transform infrared spectroscopy (FT-IR) indicated the effective immobilization and conformation retention of HRP on hp-TiO2. HRP immobilized on hp-TiO2 exhibited direct, reversible, and surface-controlled redox reaction with the electron transfer rate constant of 5.46 s(-1). Furthermore, the immobilized HRP exhibited a wide linear detection range from 1.0 to 524.0 µM. The detection limit, based on a signal-to-noise ratio of 3, was down to 0.87 µM. The apparent Michaelis-Menten constant (Km(app)) of the immobilized HRP was 0.223 mM. In addition, the sensor possessed appreciable repeatability, reproducibility and remarkable stability for the sensitive determination of H2O2. Thus, this kind of hp-TiO2 can be used as an attractive material for immobilizing proteins and constructing biosensors.
