Characterization and Pathogenic Study of Plant Mediated Silver Nanoparticles Utilizing Psidium guajava Stem Bark Extract

Abstract

The formation of Silver Nanoparticles first, was recorded by color change as the addition of crude extract resulted in a quick shift in color from light brown to orange instantly. After 5 h later, dark brown color was obtained. The UV–Visible optical findings validated the production of AgNPs in the mixture, with a surface plasmon resonance spectra at 400nm. From the FT-IR spectrum of the sample investigated, the absorption peak at 3416.85 cm-1 corresponds to the stretching due to N-H, while the peak at 2923.51 cm-1 is probably associated with C-H stretch of alkane and O-H stretching, 1618.95 cm-1 peak possibly depicts C=C stretching, 1384.49 cm-1 reveals the existence of C-H bending and 1033.63 cm-1 depicted C-O stretching. The SEM result confirmed the shape of the sample in question as having mixed cubic and hexagonal structures. The XRD result revealed that the size of the particles was 44.5nm using the Scherer’s formula. Different concentrations of 100, 200, 300, 400 and 500?g/L of Silver Nanoparticles was tested against four different pathogens, namely; Staphylococcus aureus, Escherichia coli, Candida albicans, and Aspergillus niger. As the concentrations of Silver Nanoparticles of all the pathogens increase, there generally appeared to be increase in inhibition zone. At higher concentration of 500?g/L, the zones of inhibition were in the following order; 23.44mm, 18.52mm, 17.66mm, and 15.99mm for E. Coli, S. aureus, C. albicans and Aspergillus niger respectively. For each concentration investigated, E. coli, demonstrated higher zone of inhibition as opposed to all other pathogens under investigation.