An aptamer-MIP dual-recognition electrochemical sensor utilizing Au-Pt bimetallic nanoflowers and CMCS@COF-300 nanocomposites for the ultrasensitive detection of aflatoxin B1.

BACKGROUND: Aflatoxin B1 (AFB1), as a Group 1 carcinogen designated by IARC, poses severe threats to global food safety due to its extreme toxicity and widespread contamination in crops like corn, peanuts, and cereals. Current detection technologies, including ELISA and strips, face critical limitations, such as insufficient sensitivity and weak anti-interference ability. The existing sensors with a single recognition mechanism are prone to producing false positive signals in complex food matrices, so the development of new detection methods with high selectivity and stability has become an urgent need in the field of food safety monitoring.

RESULTS: This sensor is based on a dual recognition mechanism that employs molecularly imprinted polymer (MIP) and aptamer (Apt). The sensor utilizes carboxymethyl chitosan covalent organic framework material (CMCS@COF-300), which is further functionalized with Au-Pt bimetallic nanoflowers (Au-PtNFs) to enhance conductivity. By combining density functional theory-optimized MIP with specific Apt, a novel "Apt-MIP hybrid recognition interface" is established. This interface maximizes the advantages of the ordered porous structure of COF-300 and the interface stability of CMCS, while taking advantage of the high conductivity of Au-PtNFs and the directional immobilization effect of Au-S bonds, thereby achieving effective capture and signal transduction of AFB1. Experimental results show that the sensor has excellent analytical performance, with a detection range of 10-3 to 103 ng/mL and a detection limit as low as 2.31 × 10-4 ng/mL.

SIGNIFICANCE AND NOVELTY: The composite structure of functional monomers optimized by DFT and AFB1 has been developed, optimizing the binding ratio; The Au-PtNFs bimetallic nanoflower interface developed achieves both conductivity enhancement and targeted fixation of biomolecules; The Apt-MIP collaborative recognition strategy establishes a new detection paradigm of "pre enrichment precise recognition signal amplification" through spatial hindrance regulation, providing a universal technical platform for multi toxin synchronous detection.