Development of a molecularly imprinted photochemical sensor based on Bi2O3/TiO2 NTs heterojunction extended-gate field-effect transistor for the determination of trace neomycin

A novel extended-gate field-effect transistor based molecularly imprinted polymer photoelectrochemical (EGFET-MIP-PEC) sensor was constructed for the detection of neomycin in meat samples. Bi 2 O 3 /TiO 2 NTs heterojunction materials were synthesized by anodic oxidation and electrodeposition. With neomycin as the template and 3-aminophenylboronic acid as the functional monomer, a molecularly imprinted film was prepared on the Bi 2 O 3 /TiO 2 NTs electrode by electropolymerization. The MIP/Bi 2 O 3 /TiO 2 NTs electrode was connected to an extended-gate field-effect transistor. Under the irradiation of xenon lamp simulated visible light, the holes generated on the MIP/Bi 2 O 3 /TiO 2 NTs electrodes oxidize the neomycin adsorbed by the molecularly imprinted film, generating a photovoltage, which causes the gate voltage of the extended-gate field-effect transistor to change, thereby increasing the source-drain current. The sensor showed good linearity with the source-drain current in the neomycin concentration range of 5.0 × 10 −13 –5.0 × 10 −8 mol L −1 , with a detection limit of 1.0 × 10 −13 mol L −1 (3σ/S). Owing to the amplification of EGFET on photoelectrochemical signal produced by the Bi 2 O 3 /TiO 2 NTs heterojunction with high photoelectric conversion efficiency and wider wavelength range of optical response, the sensitivity of the sensor was significantly improved. The selectivity of the sensor was remarkably enhanced due to the MIP film.