Instant green synthesis: obtaining stable nanoparticles and understanding the extract's behavior in the particle formation mechanism

Numerous plant extracts are abundant in biomolecules that can be employed in the biogenic synthesis of metallic nanoparticles owing to their potent reducing capabilities. The mechanism by which biomolecules act as reducers and expedite the reduction of silver ions remains poorly understood. This study presents an instantaneous and environmentally friendly synthesis of silver nanoparticles (AgNPs) using varying concentrations of commercially available green tea and concentrations of a dextrose-reducing solution. The AgNPs formed instantaneously, likely due to the competitive reaction between the polyphenols present in green tea and the dextrose. The best AgNPs produced using a diluted green tea solution at a concentration of 0.05 g of tea/mL (showed DPPH 0.013 ±(0.1)μmol TEAC/g, FRAP 10.3±(0.1) μmol TEAC/g and TPC 0.12±(0.001) μgGAE/g) and 100 μL of dextrose solution exhibited high stability over a period of 90 days, as confirmed by UV-Vis spectroscopy and dynamic light scattering. The resulting nanoparticles are extremely small, measuring approximately 30 to 50 nm in size, and exhibit a spherical morphology as evidenced by SEM imaging. The plasmon band of AgNPs is a more prominent and formed band in more diluted tea and higher proportions of dextrose added. Probably, the results of 2nd extraction of green tea diluted that was viewed in the results of DPPH, FRAP, TPC, and HPLC can be evidence that phenolic compounds, mainly, caffeine and gallic acid, are contributing to forming the silver nanoparticles. This fundamental knowledge showed the method employed is ecologically sound and adheres to green principles.