Rapid and sensitive aptamer-linked immunosorbent assay with aptamer-templated silver nanoparticles for detection of aflatoxin B1 in medicinal and edible food

Aflatoxin B1 (AFB1) is a potent carcinogenic mycotoxin commonly found in various medicinal and edible foods (MEFs). AFB1 in MEFs poses an inevitable threat to human health. High-performance analytical techniques are required for AFB1 detection in the quality assessment of MEFs. This work reports a novel aptamer-linked immunosorbent assay (ALISA) using aptamer-templated silver nanoparticles (AgNPs) as signal transducers for AFB1 detection. The effect of aptamer on the morphology and properties of AgNPs was systematically investigated. Aptamers with lower concentrations can induce the aggregation of AgNPs, thereby exhibiting excellent photothermal effects. Whereas, aptamers with higher concentrations mediate small-sized AgNPs' generation, demonstrating outstanding extinction coefficients. Accordingly, the effect of aptamer on the properties of AgNPs was used to construct a novel ALISA. Specifically, AFB1 aptamers were immobilized on 96-well plates via AFB1 and antibodies. In the presence of sodium borohydride (NaBH4) and silver nitrate (AgNO3), AgNPs were synthesized in a one-pot manner using the free aptamer as a template. The concentration of free aptamer can regulate AgNP morphology, affecting extinction coefficient and photothermal effect, enabling visual colorimetric and portable photothermal signal readout. When employed for AFB1 detection in MEFs, the proposed ALISA demonstrated rapid detection speed and high sensitivity, with a response time of 8 minutes and a colorimetric signal detection limit of 0.33 pg/mL. We expect that this ALISA not only enables rapid and cost-effective AFB1 detection but also offers a universal, user-friendly, and highly sensitive method for detecting other MEF hazards.