Effect of pH on Formation of Silver Nanoparticles Through Green Synthesis Approach Using Extract of Seminyak Leaves

Silver nanoparticles (AgNPs) are very useful in biomedical applications, especially for the development of anti-infection implants. For biomedical applications, AgNPs that were fabricated by green synthesis approach are more favorable than conventional approach using toxic reducing agent such as NaBH₄ or N₂H₄. In this study, AgNPs were prepared through green synthesis approach using extract of Seminyak leaves and pH were varied (5; 8 and 11) to know the influence of pH on formation of AgNPs. Visual observations reveal that increasing pH led to faster color change of samples (yellow to black) suggesting that pH is directly proportional to reaction kinetics. UV-Vis spectroscopy results unveil that strong peak at 422 nm was observed in sample with pH 11, while low and broad peak were observed in sample with pH 5 and 8, implying the presence of nano-sized particles in sample with pH 11 and larger particles in sample with pH 5 and 8. Transmission electron microscopy (TEM) characterization results shows that dispersion of nano-sized particles with particle size 15.4 ± 4.1 nm were observed in sample with pH 11, while aggregation of nano-sized particles with particle size 29.2 ± 7.2 nm and 20.8 ± 7.0 nm were observed in sample with pH 5 and 8 respectively. X-ray diffraction (XRD) results show that the intensity of Ag’s peak in sample with pH 11 is at least two times higher than other samples, indicating formation of AgNPs in sample with pH 11 is more favorable than other samples. The results suggest that formation of dispersed and uniform AgNPs in the presence of extract of seminyak leaf as capping and reducing agent were favorable at high pH conditions.