Electrochemiluminescence and Fluorescence Dual-Mode Monitoring of Aflatoxin B1 Production Based on Single Ru-MOF Particles and FITC Luminophores

Herein, an electrochemiluminescence (ECL) and fluorescence (FL) dual-mode imaging biosensing platform was developed for onsite and dynamic monitoring of aflatoxin B1 (AFB1) production in the corn molding process. Zinc metal organic framework structures encapsulated with Ru(bpy)₃²⁺ (Ru-MOF) were employed as ECL signal probes for single particle imaging with stable luminescent intensity and high emission efficiency. Fluorescein Isothiocyanate (FITC) luminophores, served as fluorescent probes, were conjugated with AFB1 aptamer modified on the electrode surface, which enabled the observation of green luminescent spots in FL mode. When exposed to target AFB1, FITC luminophores detached from the surface of electrode, leading to a notable decrease in the number of green luminescent spots. Single Ru-MOF particles were then immobilized onto the surface of electrode through DNA coupling and discernible luminescent spots could be watched in ECL mode. Under optimal circumstances, a dual-mode imaging platform was constructed for AFB1 determination with a linear relationship of 1.0 fg/mL to 1.0 pg/mL in both ECL and FL mode. The detection limit (LOD) was 0.89 fg/mL in FL mode and 0.84 fg/mL in ECL mode, which demonstrated superior sensitivity. The imaging biosensor was established for dynamic tracking of AFB1 production in corn molding process. The results showed that aflatoxin production occurred more rapidly at damaged areas of the corn compared to areas with intact surfaces. The intact corn got moldy on the third day and its surface AFB1 concentration was calculated as 14.16 fg/mL. Combining the ECL and FL imaging technology with dual-mode biosensing, this work achieves high sensitivity, accuracy and capability of dynamic monitoring for AFB1 sensing which provides innovative ideas for the rational design of aflatoxin sensors, and holds substantial promise in food safety.