A label-free electrochemical aptasensor based on NH₂-MIL-235(Fe) for the sensitive detection of citrinin

This study successfully developed a simple, specific, and ultrasensitive electrochemical aptasensor based on a label-free strategy for detecting citrinin (CIT). The NH₂-Fe-MOF nanomaterial has a large specific surface area, good biocompatibility, a simple preparation method, and low synthesis cost, so it was chosen as the aptamer's loading platform to improve the detection performance of the sensor. When CIT is present, the aptamer will specifically bind to it with a conformational change that prevents electron transfer to the electrode surface. Based on this, CIT could be quantitatively detected by measuring the change of differential pulse voltammetric (DPV) responses of the [Fe(CN)₆]^3-/4- peak current. Under optimized experimental conditions, the proposed aptasensor showed a low detection limit of 4.52 × 10^-11 g mL^-1 and a wide linear range of 0.1 to 1 × 10⁴ ng mL^-1. Furthermore, the proposed aptasensor shows excellent selectivity, reliable stability, and significant potential for the ultrasensitive detection of CIT in practical applications.