Aptamer-gated FRET nanosensor based on UCNPs-AuNSs for sensitive detection of methylmercury in seafood matrices

Methylmercury (CH₃Hg⁺) is the most toxic form of mercury found in fish, shellfish, and other aquatic organisms and poses significant risks to human health through the food chain. The present study reports the development of a fluorescence aptasensor for the quantification of CH₃Hg⁺ using aptamer-functionalized gold nanostars (AuNSs) and complementary DNA-functionalized alendronic acid-modified upconversion nanoparticles (ADA-UCNPs). The ADA-UCNPs-AuNSs fluorescence aptasensor employed an on-off detection mode and completed the detection within 60 min. The developed fluorescence aptasensor exhibited a good linear response to CH₃Hg⁺ over the concentration range of 0.5 to 20.0 µM, with a limit of detection of 0.37 µM. The aptasensor exhibited satisfactory accuracy and precision, with relative standard deviations within the evaluated CH₃Hg⁺ concentration range and recoveries of 91.00% to 99.20% in aquatic products. The newly constructed aptasensor also showed satisfactory selectivity and resistance to interference and maintained good stability, supporting its potential for practical application in food monitoring.