A green synthesis approach is reported for the synthesis of gold nanoparticles (GNPs) using the leaf extract of Coreopsis lanceolata. The synthesized GNPs were effectively utilized in the detection of aflatoxins at low concentrations based on the metal enhanced fluorescence principle. The structural characteristics of the GNPs were analyzed by UV-Vis spectroscopy, TEM and spectrofluorimetry. Bioreduction of auric chloride by C. lanceolata leaf extract resulted in the synthesis of spherical, homogenous GNPs. Further GNPs were conjugated with anti-aflatoxin antibodies and aflatoxin B1 to study the metal enhanced charge transfer between the nanoparticles and aflatoxins, which can be effectively utilized in the detection of aflatoxins at very low concentrations. The studies showed up to a 10-fold increase in the fluorescence intensity of aflatoxin B1 at picogram levels. Linearity was found to be in the range of 10 picogram to 500 picogram with a regression coefficient R2 = 0.970. The limit of detection was found to be 5 picogram. Thus the fluorescent GNPs synthesized by this green route can be effectively used in the detection of aflatoxins at sub-nanogram levels by utilizing the metal enhanced fluorescence principle.
