Green synthesis of carbon dots-functionalized silver nanoparticles for SERS-based detection of thiram fungicide

This study reports the reduction of AgNO3 using green-synthesized carbon dots (CDs) derived from the leaf extract of Datura metel without the aid of any chemical-reducing agent. The CDs act as both reducing and stabilizing agent to synthesize CDs-functionalized silver nanoparticles (Ag/CDs) and are employed for surface-enhanced Raman spectroscopy (SERS)-based detection of thiram fungicide. The formation of Ag/CDs is confirmed with UV-Vis absorption spectroscopy and Raman spectroscopy. The synthesized Ag/CDs exhibit high stability and the fabricated SERS substrate exhibited a detection range of 10(-3) to 10(-8) M with a corresponding correlation coefficient of 0.98. The obtained minimum detection limit of thiram is 10(-8) M with an enhancement factor of 1.3 x 10(5) which is much lower than the maximum allowed residual limit of 7 ppm. This study emphasizes the green route to synthesize CDs-functionalized stable AgNPs for the SERS-based detection of thiram fungicide and explained the sensing mechanism.