An “off-on” electrochemical luminescence biosensor with aggregation-induced emission for ultrasensitive detection of aflatoxin B1

This work describes a novel “off-on” biosensor for super-sensitive and selective detection of aflatoxin B1 (AFB1). In the biosensor, electrochemiluminescence (ECL) and aggregation-induced emission (AIE) work together to enhance ECL performance by a dibenzo-[b,d]thiophene sulfone-based conjugated microporous polymer, and hairpin DNA1 (H1) and ferrocene (Fc)-apt act as the switches for the "off-on" mode. In the absence of target AFB1, the ECL signal is inhibited because of the steric-hindrance effect, and the biosensor remains in the “off” state. In the presence of AFB1, ECL signal recovery is observed caused by the specific recognition between the AFB1 and Fc-apt, i.e., the biosensor changes to the “on” state. Under optimal experimental conditions, AFB1 can be quantified from 1 pg·mL−1 to 1 μg·mL−1 with an ultralow detection limit of 0.46 pg·mL−1 by the “off-on” biosensor. The biosensor exhibited good practicability for AFB1 assay in corn samples, thus providing a simple and sensitive method for monitoring food safety.