A ratiometric fluorescent biosensing platform based on CDs and AuNCs@CGO for patulin detection

Background: Patulin (PAT) is a mycotoxin, usually found in fruit and their products, that can potentially be harmful to human health. In order to achieve rapid detection of mycotoxins and ensure the safety of food. This study reported a novel ratiometric fluorescent aptasensor for PAT detection. In this study, we used aptamer as the recognition element, Hybrid double stranded modified with fluorescent substances as the fluorescent donor, and AuNCs@CGO as the fluorescent acceptor. After the addition of PAT, the ratiometric fluorescence "turn on" response was exhibited. Results: The AuNCs@CGO are obtained by amide reaction between BSA-AuNCs and carboxylated graphene oxide (CGO). The prepared AuNCs@CGO can shorten the time of FRET effect and exhibit highly efficient quenching ability by adsorption effects (it-it stacking and electrostatic gravity) on the Aptamer-modified CDs. When the target PAT bound specifically to the CDs-apt, the fluorescence of the CDs-apt would recover, while the fluorescence of ROX modified cDNA remained unchanged. This ratiometric fluorescence response improved the accuracy of PAT detection. In addition, the proposed had good linearity for PAT in the range of 0.1-50 ng/mL with a limit of detection 0.16 ng/mL. The recovery of standard addition in grapes were 95.9%-105.4 %. Significance: An effective fluorescent detection method for PAT was constructed based on aptamer and nanomaterials. This new fluorescent biosensor has the characteristics of simple synthesis, easy operation, high sensitivity, strong selectivity and a low LOD, which may be a promising idea and platform for the detection of food safety hazard factors.