Synthesis and characterisation of gold nanoparticles from acacia leaf and to evaluate anticariogenic activity

To synthesise the gold nanoparticles (AuNPs) using Acacia catechu through biogenic synthesis and evaluate their antimicrobial efficacy against S. mutans and E. coli in vitro.

Green synthesised AuNPs were characterised using the ultraviolet-visible (UV-Vis) spectroscopy, and the size and shape of the synthesised nanoparticles were evaluated using the transmission electron microscopy (TEM). The antimicrobial efficacy of AuNPs (30/60/100 μl) against S. mutans/E. coli was evaluated on the Mueller-Hinton agar by measuring the zone of inhibition (ZOI) with ampicillin (15 μl) as a positive control.

The synthesised AuNPs were confirmed using the UV-Vis spectroscopy with peaks at 540 nm, and the size of the particle estimated using the TEM was between 5 and 15 nm. The antimicrobial efficacy of AuNPs was comparable to that of ampicillin against S. mutans/E. coli, but the difference was not significant. The antimicrobial effects increased in a dose-dependent fashion but were comparable across all concentrations and ampicillin.

Green synthesised AuNPs exhibited significant antibacterial activity against S. mutans and E. coli at par with commercial ampicillin and demonstrated the potential towards anticariogenic agent for future use in dentistry.