Detection of Extracellular H_(2)O_(2) Released from Human Liver Cancer Cells Based on TiO_(2) Nanoneedles with Enhanced Electron Transfer of Cytochrome c

摘要

The high conductive TiO_(2) nanoneedles film is first employed as a support matrix for immobilizing model enzyme, cytochrome c (cyt c) to facilitate the electron transfer between redox enzymes and electrodes. Reversible and direct electron transfer of cyt c is successfully achieved at the nanostructured TiO_(2) surface with the redox formal potential (E~(0')) of 108.0 +- 1.9 mV versus Ag|AgCl and heterogeneous electron transfer rate constant (k_(s)) of 13.8 +- 2.1 s~(-1). Experimental data indicate that cyt c is stably immobilized onto the TiO_(2) nanoneedles film and maintains inherent enzymatic activity toward H_(2)O_(2). On the basis of these results, the cyt c-TiO_(2) nanocomposits film is capable of sensing H_(2)O_(2) at a suitable potential, 0.0 V (vs Ag|AgCl), where not only common anodic interferences like ascorbic acid, uric acid, 3,4-dihydroxyphenylacetic acid but also a cathodic interference, O_(2), are effectively avoided. Besides high selectivity, the present biosensor for H_(2)O_(2) shows broad dynamic range and low detection limit. These remarkable analytical advantages, as well as the characteristic of TiO_(2) nanoneedles film such as high conductivity, biocompatibility, and facile ability to miniaturize establishes a novel approach to detection of extracellular H_(2)O_(2) released from human liver cancer cells.