Biosynthesized gold nanoparticles-doped hydroxyapatite as antibacterial and antioxidant nanocomposite

Abstract

A composite of hydroxyapatite (HA) doped with green synthesized gold nanoparticles (Au NPs) was prepared. Au NPs were produced via the bioreduction of HAuCl _4 with Clitoria ternatea flower extract and utilized in HA synthesis, using Ca(OH) _2 and ammonium diphosphate as precursors. The aim of this research was to analyze the structure of the composite and conduct an antibacterial activity test involving Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae , and Streptococcus pyogenes . In addition, antioxidant activity was evaluated by 2,2-diphenyl-1-picrylhydrazyl radical scavenging. Au NP formation monitoring was conducted by UV–visible spectroscopy and particle size analysis, and the synthesized composite was studied using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results revealed homogeneously dispersed Au NPs (particle size ranging from 5 to 80 nm) in the HA structure. The nanocomposite demonstrated enhanced antibacterial activity against the tested bacteria compared to HA, with minimum inhibition concentrations of 3 μ g ml ^−1 for E.coli and S.aureus and 10 μ g ml ^−1 for K. pneumoniae and S. pyogenes . The nanocomposite expressed antioxidant activity, as shown by 2,2-diphenyl-1-picrylhydrazyl scavenging activities of 66% and 58% at concentrations of 100 μ g ml ^−1 and 50 μ g ml ^−1 , respectively.

Keywords

• Au nanoparticles
• hydroxyapatite
• green synthesis
• antibacterial
• antioxidant