Conjugation of Silver and Gold Nanoparticles for Enhancing Antimicrobial Activity

Silver and gold nanoparticles are promising agents that can enhance the antibacterial activity of conjugated/capped extract of plant compounds. The aim of our study is to synthesize silver nanoparticles from Gymnema sylvestre plant extract. In this study, the antimicrobial activity of conjugated silver which was green synthesized and gold nanoparticle that was obtained from a commercial source was evaluated using disk-diffusion method against Escherichia coli and Aspergillus niger. Transmission electron microscopy, scanning electron microscopy, ultraviolet-visible spectroscopy, and Fourier transform infrared spectroscopy analyses were also carried out to characterize the conjugated silver and gold nanoparticles. The conjugation of silver and gold nanoparticles was performed chemically using 16-mercaptodecanoic acid. Our results revealed that conjugated silver and gold nanoparticle both showing larger inhibition zones against E. coli and A. niger. The minimum inhibitory concentration (MIC) of the above metallic conjugation was found to be stable with MIC was reported to be 1 mM. When comparing the sample analysis on conjugation of gold and silver nanoparticles against E. coli and A. niger, the antimicrobial activity recorded was 2.0 ± 0.01 and 2.32 ± 0.04 cm, respectively, with no significance difference was found (P = 0.85). In conclusion, the combination of two different nanoparticles is efficient for microbial inhibition and can be useful for studying antimicrobial activities with the combination of different nanomaterials in future.