Bio-inspired gold nanoparticles synthesis and their anti-biofilm efficacy

Abstract

Gold nanoparticles (AuNPs) are ‘smart nanomaterials’ with a variety of applications in the different fields. The conventional methods used for AuNPs have some drawbacks and therefore, search of an alternative ‘green method’ is of high importance. In this study, Acinetobacter baumannii AB01 isolated from an infected apple sample was used as a green route for AuNPs synthesis. Effect of various physicochemical parameters such as pH, temperature, cell density and gold chloride salt concentrations on AuNPs synthesis was studied. These AuNPs were further characterized by UV–Vis spectrophotometer, transmission electron microscopy (TEM), energy dispersive spectroscopy, X-ray diffraction and dynamic light scattering. TEM images study showed presence of an extracellular polymeric substance around cells of A. baumannii AB01. The synthesized biogenic AuNPs were tested for their antibacterial activity by well diffusion method. Anti-biofilm efficacy of AuNPs was tested on the glass slide surfaces against the biofilms of Pseudomonas aeruginosa, Vibrio cholera and Brevibacterium linens and visualised by using a fluorescence microscopy. Biofilm formation was reduced about 60–80 % when compared with control biofilm (without AuNPs). Effect of different AuNPs concentrations on biofilm formation in microtiter plates was studied by 96-well plate assay. The bacterial biofilm inhibition (%) was increased with increasing concentrations of AuNPs.