Enhanced antibacterial activity of size-controlled silver and polyethylene glycol functionalized silver nanoparticles

In the present study, the microemulsion-assisted co-precipitation method was utilized for the synthesis of the size-controlled silver nanoparticles and PEGylated silver nanoparticles at different pH (10–12). The nanoparticles were characterized by X-ray diffraction, Fourier-transform infra-red spectroscopy, transmission electron microscopy and energy-dispersive X-ray spectroscopy. These particles were employed for bactericidal activity against Staphylococcus aureus and compared with levofloxacin as a standard bactericidal drug. The results showed that smaller silver nanoparticles (SNPs) possessed higher antibacterial activity. The activity was further enhanced using polyethylene glycol as surface functionalization agent. The pronounced bactericidal effect can be associated to the increase in hydroxyl ions on the surface of silver nanoparticles. The sample P₅₀₀₀SNPs (PEG of M. wt. 5000) exhibited outstanding bactericidal activity against S. aureus and displayed the zone of inhibition (ZOI) 29 mm at pH 10. Furthermore, PEGylation of silver (smaller size of silver ions) with higher molecular weight has shown pronounced bactericidal effect. Therefore, PEGylated SNPs with higher molecular weight are recommended as excellent disinfectants.