N-doped HOFs nanoenzymes enable dual-mode colorimetric/electrochemical aptasensing of AFB1

Aflatoxin B1 (AFB1), a highly toxic mycotoxin prevalent in agricultural products, poses severe health threats. Addressing the critical need to mitigate AFB1-induced food safety risks, the primary objective of this study was to develop an accurate and ultrasensitive colorimetric/electrochemical (CL/EC) dual-mode aptasensor for AFB1 detection. To achieve this aim, we employed 3,3′,5,5′-tetramethylbenzidine (TMB) as a dual-function indicator. The catalytic oxidation of TMB generated oxidized oxTMB, concurrently producing colorimetric and electrochemical signal. Central to realizing the sensor's dual functionality, BSA@HOF-101 nano-enzymes were generated by in situ encapsulation of bovine serum albumin (BSA) in hydrogen-bonded organic frameworks (HOFs), which were indispensable enzyme mediators for the dual function of TMB. To specifically detect AFB1, BSA@HOF-101 was coupled with aptamer (Apt). The CL/EC dual-mode aptamer sensor offered detection of AFB1 across a concentration range from 10 −11 to 10 −7  g/mL. In addition, the sensor was successfully applied to the detection of AFB1 in corn and peanut samples with recoveries as high as 97.4 %–104.0 %. Collectively, this work established a robust analytical strategy with a dual-mode readout, providing a promising solution for the rapid and precise on-site monitoring of AFB1 contamination.