An CuInS2 photocathode for the sensitive photoelectrochemical determination of microRNA-21 based on DNA–protein interaction and exonuclease III assisted target recycling amplification

A photocathode is described for the determination of microRNA-21 by using CuInS 2 as an active photocathode material. Exonuclease III assisted target recycling amplification was employed to enhance the detection sensitivity. The TATA-binding protein (TBP) was applied to enhance steric hindrance which decreases the photoelectrochemical intensity. This strategy is designed by combining the anti-interference photocathode material, enzyme assisted target recycling amplification and TBP induced signal off, showing remarkable amplification efficiency. Under the optimized conditions, the detection limit for microRNA-21 is as low as 0.47 fM, and a linear range was got from 1.0 × 10 −15  M to 1.0 × 10 −6  M. Schematic representation of sensitive photoelectrochemical detection of microRNA-21.CuInS 2 is used as an active photocathode material. Combined Exonuclease III assisted target recycling amplification and TATA-binding protein decreased of photoelectrochemical intensity, the detection limit was 0.47 fM with good selectivity. (miR-21: microRNA-21; CS: chitosan).