Antifouling electrochemical aptasensor based on a polyzwitterion copolymer for analyzing aflatoxin B1 in food

Minimizing sample pretreatment while maintaining specific analyte binding and eliminating non-target interference from food matrices remains challenging in food safety analysis. Here, we fabricated an antifouling surface using a dopamine-triggered polyzwitterion copolymer, polydopamine-poly(carboxybetaine methacrylate-co-N-(2-aminoethyl) methacrylamide hydrochloride) [pDA-p(CBMA90-co-AEMA10)], via in-situ polymerization and the Michael addition reaction. Compared with homopolymers that were prepared using a single carboxybetaine methacrylate (CBMA), the copolymer formed by regulating the proportions of CBMA and (2-aminoethyl)methacrylamide hydrochloride monomers outperformed in terms of antifouling ability. Thiol-modified aptamers were subsequently immobilized on the polydopamine layer via Michael addition to construct an electrochemical sensor for aflatoxin B1 (AFB1). The sensor exhibited strong antifouling performance in various simulated and real food matrices, with signal suppression as low as 0.54 %. It also achieved a low detection limit of 0.19 pg mL^-1 and enabled sensitive AFB1 detection using a simple sample pretreatment method, with recovery rates ranging from 94.6 % to 105.8 %.