Sensitive glyphosate electrochemiluminescence immunosensor based on electrografted carbon nanodots

A novel electrochemiluminescence (ECL) immunosensor based on electrografted carbon nanodots (CND) is developed for the sensitive determination of glyphosate in soy milk and tea. Nitrogen rich CND were synthesized by microwave radiations using mild conditions and following the principles of green chemistry. L-Arginine and 3,3'-diamino-N-methyldipropylamine were selected as precursors. CND were exhaustively characterized as well as the resulting nanostructured electrodes after CND electrografting. The high stability of CND nanostructured electrode together with the high electrical conductivity and the improvement of the electrochemiluminescent properties from the luminophore [Ru(bpy)(3)](2+) makes it an excellent electrochemiluminescence detection platform for biosensing assays. The application to biosensors was assessed by combination with an immunoassay based on magnetic nanoparticles, in which anti-glyphosate-IgG coupled magnetic particles (MP-Ab) was used as recognition element of the analyte, glyphosate. The developed ECL immunosensor was successfully applied for the detection of glyphosate in a wide linear range from 28.9 to 200 pg/mL, a sensitivity of 3.38 x 10(-3) mL/pg and a detection limit of 8.66 pg/mL. The immunosensor response is stable and reproducible and it has been applied to the determination of glyphosate in tea and soy milk, with results that agree with those provided by an ELISA kit involving the same immunoreagents.