Evaluation of ‘green’ synthesis and biological activity of gold nanoparticles using <i>Tragopogon dubius</i> leaf extract as an antibacterial agent

Abstract

Currently, the use of 'green' synthesised nanoparticles with environmentally friendly properties is considered a novel therapeutic approach in medicine. Here, the authors evaluated gold nanoparticles (AuNPs) conjugated with <i>Tragopogon dubius</i> leaf extract and their antibacterial activity in vitro and in vivo. Colour changes from yellow to dark brown and a peak at 560 nm on ultraviolet-visible spectroscopy confirmed the formation of nanoparticles. Additionally, transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy analyses were performed to determine particle sizes and functional groups involved in gold reduction. Moreover, using standard micro-dilution and disc-diffusion assays against <i>Klebsiella pneumoniae, Bacillus cereus, Escherichia coli</i>, and <i>Staphylococcus aureus</i>, the antimicrobial properties of synthesised AuNPs were investigated. To confirm antibacterial activity, synthesised AuNPs were applied in a rat model on burn wounds infected with <i>S. aureus</i>, and the nanoparticles were as effective as tetracycline in bacterial reduction and wound healing. In conclusion, the synthesis of AuNPs with aqueous <i>T. dubius</i> extract was rapid, simple, and inexpensive, and the synthesised nanoparticles had significant antibacterial activity in vitro and in vivo.