Antibacterial activity and catalytic activity of biosynthesised silver nanoparticles by flavonoids from petals of Lilium casa blanca

Abstract

Biosynthesis of silver nanoparticles (AgNPs) by flavonoids extracts from petals of Lilium casa blanca was reported. Reaction conditions such as pH, concentration of flavonoids or silver nitrite, reaction temperature and reaction time were optimised to control the formation of the AgNPs. Synthesised AgNPs were characterised by UV-Vis spectroscopy, transmission electron microscopy (TEM), dynamic light scattering (DLS), zeta potential measurement and Fourier transform infrared (FT-IR) spectroscopy. Stability, antibacterial and catalytic activities of the synthesised AgNPs were also discussed. The optimum synthetic conditions were 10 mL 20 mM AgNO3 added to 1 mL flavonoids extracts, adjusting pH to 10, and reacted at 70°C for 1 h. The formation of AgNPs was confirmed by UV-Vis spectroscopic analysis, which showed maximum absorption peak at 404 nm. TEM analysis revealed spherical particles with size about 12.7 nm. FT-IR spectra revealed flavonoids were present on the surface of the AgNPs. AgNPs showed highest antibacterial activity against Escherichia coli and Salmonella, and the lesser antibacterial activity of AgNPs was found against Bacillus subtilis and Staphylococcus aureus. The biosynthesised AgNPs showed good catalytic activity as well by hydroboration of p-nitrophenol. Catalytic reduction followed pseudo-first-order kinetic.