Formation of BiMoO-BiS Heterostructure: A Proof-Of-Concept Study for Photoelectrochemical Bioassay of l-Cysteine.

A novel signal-increased photoelectrochemical (PEC) biosensor for l-cysteine (L-Cys) was proposed based on the BiMoO-BiS heterostructure formed on the indium-tin oxide (ITO) electrode. To fabricate the PEC biosensor, BiMoO nanoparticles were prepared by a hydrothermal method and coated on a bare ITO electrode. When L-Cys existed, BiS was formed on the interface of the BiMoO/ITO electrode by a chemical displacement reaction. Under the visible light irradiation, the BiMoO-BiS/ITO electrode exhibited evident enhancement in photocurrent response compared with the BiMoO/ITO electrode, owing to the signal-increased sensing system and the excellent property of the formed BiMoO-BiS heterostructure such as the widened light absorption range and efficient separation of photo-induced electron-hole pairs. Under the optimal conditions, the sensor for L-Cys detection has a linear range from 5.0 × 10 to 1.0 × 10 mol L and a detection limit of 5.0 × 10 mol L. The recoveries ranging from 90.0% to 110.0% for determining L-Cys in human serum samples validated the applicability of the biosensor. This strategy not only provides a method for L-Cys detection but also broadens the application of the PEC bioanalysis based on formation of photoactive materials.