Detection of Extracellular H₂O₂ Released from Human Liver Cancer Cells Based on TiO₂ Nanoneedles with Enhanced Electron Transfer of Cytochrome c

Abstract

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.

Bio-inspired porous antenna-like nanocube/nanowire heterostructure as ultra-sensitive cellular interfaces

“…This phenomenon is attributed to the effect of PMA for inducing H 2 O 2 production from the cells. 10 An anodic current increase of B32.5 mA is obtained in 15 s, which is similar to the time scale reported previously. 38 No response is observed at the bare TiO 2 NWs with the same addition of PMA.…”

“…In addition, the injection of the catalase solution (300 U ml À1 in PBS) reduces the current level to almost the background current level; catalase is known to inhibit the PMA function. 10 Accordingly, the increase in cathodic current at the PB-TiO 2 antenna NW biointerface located near the cells is ascribed to the enzymatic reduction of H 2 O 2 , which is effectively mediated by the PB nanocubes grown on the TiO 2 NWs interface.…”

“…Among them, H 2 O 2 is an important reactive oxygen species that can diffuse across cell membranes and lead to oxidative protein modification. 10 Prussian blue (PB) is known as an artificial enzyme peroxidase with porous frameworks, which can efficiently reduce H 2 O 2 at extremely rapid catalytic rates with low overpotentials. 11 For example, molecularly imprinted PB films 12 and PB/carbon nanotubes 13 have been used for biosensing because their low overpotentials can exclude interferences from coexisting substances, such as ascorbic acid (AA), uric acid and glucose.…”

TiO2-graphene nanocomposite for electrochemical sensing of adenine and guanine

“…Due to its good biocompatibility, high conductivity and low cost, TiO 2 in various forms such as nanoparticles, nanoneedles and nanotubes, has become an attractive electrode material for electrochemical sensors and biosensors applications [17][18][19][20][21][22][23][24]. Recently, Liu et al fabricated the electrochemical sensor by casting TiO 2 nanotubes film onto glassy carbon electrode (GCE) surface.…”

Nanostructured metal oxide-based biosensors

“…Such biosensors exhibit a linear range of 2.0-580 μM for α-MnO 2 nanoparticles and 1.0-790 μM for β-MnO 2 nanowires with detection limits of 1.0 and 0.3 μM, respectively [48]. Luo et al [49] fabricated a highly conductive TiO 2 -nanoneedle fi lm as a support for the immobilization of cytochrome c to facilitate electron transfer between redox enzymes and electrodes. In this system, they found inherent enzymatic activity towards H 2 O 2 released from human liver cancer cells.…”