Carboxyl porphyrin as signal molecule for sensitive fluorescent detection of aflatoxin B via ARGET-ATRP.

In this work, a novel fluorescent biosensor for sensitive detecting of aflatoxin B (AFB) was constructed through activators regenerated by electron transfer for atom transfer radical polymerization (ARGET-ATRP) for the first time. The AFB antigen was immobilized on the carboxy magnetic beads (MBs) by forming a sandwich-type "aptamer-antigen-antibody" immune system. Then, acrylamid (AM) was introduced through ARGET-ATRP to provide binding sites for the signaling molecules. Finally, carboxy porphyrins (TPP*) were connected with monomers through an amide bond and fixed on the MBs. Under the optimal experimental conditions, the fluorescence intensity and the logarithm of the concentration of AFB showed a good relationship from 100 fg mL to 100 ng mL, with the limit of detection (LOD) as low as 8.38 fg mL. In addition, the method shows good selectivity and excellent reproducibility. More importantly, the biosensor has applied to the quantitative analysis of AFB in four Chinese medicines, and this strategy could potentially serve as a novel means for sensitive detecting of AFB in complex matrices.