Nanozyme-assisted ratiometric photoelectrochemical aptasensor over CuO nanocubes mediated photocurrent-polarity-switching based on S-scheme FeCdS@FeInS heterostructure.

The controllable modulation of the response mode is highly attractive for the construction of photoelectrochemical (PEC) sensors with improved sensitivity and anti-interference ability in complex real samples matrix. Here, we present a charming proof-of-concept ratiometric PEC aptasensor of enrofloxacin (ENR) analysis via the controllable signal transduction. Different with the traditional sensing mechanism, this ratiometric PEC aptasensor integrates the anodic PEC signal induced by PtCuCo nanozyme-catalyzed precipitation reaction and the polarity-switching cathodic PEC response mediated by CuO nanocubes on S-scheme FeCdS@FeInS heterostructure. Taking advantages of the photocurrent-polarity-switching signal response model and the superior performance of the photoactive substrate material, the proposed ratiometric PEC aptasensor displays a good detection linear range for ENR analysis from 0.01 pg mL to 10 ng mL, with a detection limit of 3.3 fg mL. This study provides a general platform for detecting interested trace analytes in real samples and expands the diversity of sensing strategy design.