Biosynthesis of Gold Nanoparticles Assisted by Lipopeptide Biosurfactant Derived from Acinetobacter junii B6 and Evaluation of Its Antibacterial and Cytotoxic Activities

In the present work, the lipopeptide biosurfactant (LPB) produced by Acinetobacter junii B6 was applied for the production of gold nanoparticles (Au NPs). Several methods, including transmission electron microscopy (TEM), UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), and scanning electron microscopy (SEM), were used to determine the properties of the synthesized Au NPs. TEM and SEM images of Au NPs showed spherical and mostly hexagon-shaped and well-dispersed nanoparticles in the range of 10–17 nm. Cytotoxic activity of the Au NPs (assisted by WST-1 assay) revealed IC50 (μg/ml) of 89.08 ± 0.4, 646.12 ± 0.5, 3.37 ± 0.1, and 770 ± 0.15 against cell lines of U87, A549, MCF7, and 3T3, respectively. However, the anti-proliferative activities of biogenic Au NPs were significantly lower (IC50 of 770 ± 0.15 μg/mL) than HAuCl4 (IC50 of 0.26 ± 0.03 μg/mL) against 3T3 normal cell. The attained results of the antibacterial effect of the produced Au NPs and Au3+ ions revealed that Au3+ ions had a higher inhibitory effect than Au NPs against 3 Gram-positive and 4 Gram-negative bacterial strains. In the present study, we introduced a green approach for the synthesis of Au NPs using non-toxic and biodegradable LPBs in the absence of any chemical reducing agent.