Green synthesis of silver nanoparticles and evaluation of their anti-bacterial activities: use of Aloe barbadensis miller and Ocimum tenuiflorum leaf extracts

Abstract

The presence of various phytochemicals makesthe leaf extract-based green synthesis advantageous toother conventional methods, as it facilitates the productionof non-toxic by-product. In the present study, leaf extractsfrom two different plants:Aloe barbadensis millerandOci-mum tenuiflorum, were used to synthesise Ag nanoparticles.The absorbance at 419-432 nm from UV-visible spectroscopyindicates the formation of Ag in the synthesised samples.The effect of precursors’ concentration on the stability, sizeand shape of the synthesised samples has also been in-vestigated at constant heating temperature, stirring time,and the pH of the solution. The TEM results showed thatall the synthesised samples of nanoparticles demonstratedstability with a size range of 7-70 and 9-48 nm withAloebarbadensis millerandOcimum tenuiflorumleaf extracts,respectively. The formation of smaller Ag nanoparticlesdue to utilisation of different precursor concentration andleaf extracts was also explained. The synthesised samples’anti-bacterial activity was examined against the pathogens,Bacillus subtilis,Staphylococcus aureus, andEscherichiacoli. In general, the green synthesis approach established aprospective for developing highly stable Ag nanoparticleswith rigid particle shape/size distribution from differentleaf extracts for the development of better anti-bacterialagents.