A photoelectrochemical sensing strategy based on single-layer MoS modified electrode for methionine detection.

MoS, a typical transition metal disulfide, is widely used in the photoelectrochemical (PEC) sensor construction. In general, MoS based PEC sensor are "signal-on" strategies. Surprisingly, we discovered that the PEC response of MoS was quenched by methionine greatly. Based on this discovery, a reduction PEC sensing strategy utilized MoS modified electrode for methionine detection was fabricated for the first time. Experimental factors, such as, bias potential, volume of MoS and pH were studied. Under optimized conditions, the decreased intensity of the photocurrent signal was proportional to the logarithmic value of methionine concentrations from 0.1 nM to 1 μM with the detection limit of 0.03 nM. Moreover, this method exhibited good performance of excellent selectivity. And it showed potential applications in the practical determination of methionine in real-life sample. This strategy not only expands the PEC detection method but also provides a simple, rapid response, good selectivity and high sensitivity way to detect methionine.