Au-Ag NFs@Pt NCs nanozymes-driven aptasensor for sensitive visual detection of aflatoxin B1 in peanut

Nanozyme-based aptasensors still face challenges, including low catalytic activity and inverse signal correlation, which hinder their advancement in the field of food safety. To address these issues, this study developed a novel nanozyme-based colorimetric aptasensor for the high-performance detection of AFB1. Initially, a gold-silver alloy nanoframework (Au-Ag NFs) was synthesized using liposomes as a template, followed by the deposition of platinum nanoclusters on its surface, resulting in the successful preparation of the Au-Ag NFs@Pt NCs nanozyme. This nanozyme exhibited outstanding oxidase-like activity, efficiently catalyzing the oxidation of TMB, leading to a significant increase in absorbance at 652 nm and a visually observable blue color. The AFB1-specific aptamer was covalently immobilized onto the nanozyme surface through Au-S bonds, forming the Au-Ag NFs@Pt NCs@apt complex and enabling the construction of an integrated "recognition-catalysis" sensing system. Upon target recognition by the aptamer, conformational changes in the Au-Ag NFs@Pt NCs @apt-target complex reduced the masking effect of the aptamer on the surface of the nanoenzyme, thereby enhancing oxidase-like activity. Ultimately, this colorimetric aptasensor achieved an enzyme-like "turn-on" detection of AFB1. The aptasensor achieved a detection limit as low as 22.3 pg/mL, and demonstrated excellent selectivity, stability, and satisfactory recovery in spiked peanut samples. This work not only provides a promising new approach for on-site rapid screening of AFB1, but also offers novel composite material insights for designing high-performance nanozyme sensing platforms targeting other analytes.