Senna occidentalis aqueous extract for the synthesis of nanoparticles with cerium, lanthanum, copper, silver and zinc salts produces stable antimicrobial agent

Abstract

The use of aqueous plant extracts to obtain nanoparticles are promising due to theiraccessibility, low cost, and eco-friendliness. The green synthesis of different nanoparticles wascarried out to explore their antimicrobial potentials as bioactive components in waterbornecoating formulations. Solutions of zinc, cerium, lanthanum, copper, and silver salts at differentconcentrations were used as sources of metal ions for the synthesis process. Aqueous plantextract of Senna ocidentalis, a small shrub about 3 ft. high belonging to Leguminosae familywas used as a reducing and stabilizing agent. The nanoparticles synthesis involved the mixingof 10 ml of the extract in 90mL of each metal salt solution at 60ºC and pH 7 withconstant stirring. The nanoparticle synthesis was confirmed by UV-vis spectroscopy after 24hours. The same technique was used to assess the stability of the nanoparticles over time.The characterization of the nanoparticles by transmission electron microscopy and Fouriertransformed infrared spectroscopy showed stability after 30 days of synthesis. Theantimicrobial activity assay was performed against bacterial and fungal strains: Escherichia coli, Staphylococcus aureus, Chaetomium globosum and Alternaria alternata. These microorganisms wereselected due to their predominance and role in biodeterioration. Nanoparticles obtained with silverand copper solutions were stable. However, only the silver quasy-spherical nanoparticles showedantimicrobial activity against all tested strains.