Bimetallic synergy and aggregation-induced emission enhanced electrochemiluminescence aptasensor for detection of aflatoxin B1.

Aflatoxin B1 (AFB1), a highly carcinogenic mycotoxin widely contaminating agricultural products, poses a severe threat to food safety and human health, thereby necessitating the development of detection methods. Electrochemiluminescence (ECL) has emerged as an ideal analytical technique due to its near-zero background and exceptional sensitivity. However, traditional monometallic gold nanoclusters (Au NCs) suffer from inherently low ECL efficiency and poor stability. Herein, this work proposes a dual-enhancement strategy to construct a robust "signal-off-on" ECL biosensing platform for the detection of AFB1. Specifically, silver (Ag) is co-doped to synthesize GSH-Au/Ag NCs, significantly boosting the intrinsic ECL intensity via a bimetallic synergistic effect. Subsequently, these bimetallic NCs are in situ encapsulated within a metal-organic framework (ZIF-8). The rigid spatial confinement of ZIF-8 strictly triggers the restriction of intramolecular motions (RIM), thereby activating aggregation-induced emission (AIE) for secondary ECL signal amplification while endowing the GSH-Au/Ag NCs@ZIF-8 composite with outstanding structural stability. Integrating the intensely luminescent GSH-Au/Ag NCs@ZIF-8 emitter with the highly efficient Cu2O@PDA quencher, the developed ECL sensor exhibits a broad linear range from 0.001 to 100 ng/mL with a remarkable limit of detection (LOD) of 0.1186 pg/mL. This work not only provides profound insights into the synergistic ECL enhancement mechanisms driven by bimetallic doping and spatial confinement but also offers a promising paradigm for the precise quantification of trace mycotoxins in food safety monitoring.