Signal-on fluorescent strategy for label-free detection of carbendazim based on gold nanoparticles quenching graphene quantum dots

A fluorescence biosensing method based on fluorescence resonance energy transfer between gold nanoparticles (AuNPs) and graphene quantum dots (GQDs) was developed for the rapid detection of carbendazim. Upon adding the aptamer to the AuNPs solution, the aptamer binds to the AuNPs, preventing their aggregation in a high-concentration NaCl solution. Therefore, the AuNPs retain their optical properties and can quench the fluorescence of GQDs. When carbendazim is introduced, it specifically binds to the aptamer on the AuNPs, forming a complex. This interaction causes the AuNPs to lose the protective effect of the aptamer and aggregate in the high-concentration NaCl solution, leading to a loss in their ability to quench GQDs fluorescence, which increases the fluorescence intensity of the solution. This method was applied to recover carbendazim from the leaves of Chinese herbal medicines, achieving recoveries of 90.68%-106.29%. The results demonstrate that the sensor is simple, convenient, and effective.