Photo-driven self-powered biosensors for ultrasensitive microRNA detection based on metal–organic framework-controlled release behavior

“Signal-on” photoelectrochemical biofuel cell-based self-powered biosensors based on metal–organic framework-controlled release behavior were constructed for ultrasensitive microRNA detection.

A photoelectrochemical biofuel cell based on a TiO2 nanotube array fluorine-doped tin oxide photoanode

Photoelectrochemical biofuel cells can convert light and chemical energy into electrical energy using a dye-sensitized titania (TiO2) fluorine-doped tin oxide photoanode and a platinum-coated fluorine-doped tin oxide cathode. TiO2 of the photoanode serves both as a support for dyes and as an electron-transporting medium, the structure of which can limit electron trapping and charge transporting and then affect the performance of the photoelectrochemical biofuel cells. TiO2 nanotube array films have been shown to enhance the efficiencies of both charge collection and electron injection, and hence a vertically aligned TiO2 nanotube array is investigated as a conductor for the tetrakis(4-carboxyphenyl)porphyrin dye to construct a new two-compartment photoelectrochemical biofuel cell. The photoelectrochemical biofuel cell containing the TiO2 nanotube array photoanode yields a short-circuit (Isc) current of 110 μA and an open-circuit (Voc) potential of 1010 mV. In contrast, the photovoltaic parameters, Isc and Voc of the photoelectrochemical biofuel cell with the mesoporous TiO2 nanocrystal fluorine-doped tin oxide photoanode, are 96.96 μA and 740 mV, respectively. Photovoltaic measurements show that the maximum incident photon-to-collected electron conversion efficiency was 58% at 430 nm through the spectral range (400–800 nm) for the photoelectrochemical biofuel cell with the TiO2 nanotube array fluorine-doped tin oxide photoanode. These results revealed that the TiO2 nanotube array had great potential for the photoelectrochemical biofuel cells.

Photoanode of Photoelectrochemical Biofuel Cell Sensitized by Magnesium Tetraphenylporphyrin

Magnesium tetraphenylporphyrin (MgTPP) had been synthesized with tetraphenylporphyrin (TPP) and magnesium acetate according to reported paper. The photoanode of photoelectrochemical biofuel cell (PEBFC) was constructed including TiO2 conductive film and photosensitizer Magnesium Tetraphenylporphyrin. The interaction between MgTPP sensitizer and TiO2 was evaluated by X-ray photoelectron spectra, indicating that the MgTPP adsorbed on TiO2 was easier to accept electrons compared with synthesized MgTPP itself. The spectroscopic properties of synthesized MgTPP and MgTPP-sensitization TiO2 in dichloromethane solution were obtained by Uv-vis absorption spectra, demonstrating that the characteristic absorption peaks of MgTPP on TiO2 displayed slight red shift compared with synthesized MgTPP. The photocurrent action spectrum evidenced that current of the PEBFC originated from MgTPP-sensitization TiO2 photoanode.