Influence of the parameters governing antagonistic efficacy of bimetallic Au/Ag nanoparticles synthesized by femtosecond laser ablation

Abstract

The development of novel antagonistic nanoparticles requires information about the factors that influence the antibacterial and anti-biofilm activity. Even though antibacterial studies relating size and shape of metallic nanoparticles were reported earlier we attempted to comprehend the parameters that control the antibacterial and anti-biofilm efficacy of bimetallic Au/Ag nanoparticles prepared by femtosecond laser ablation. The synthesis of bimetallic nanoparticles was done according to our previous article. Absorption spectra and transmission electron microscopy (TEM) validated the buildup of bimetallic nanoparticles. The samples were investigated for antibacterial activity against Gram negative (Pseudomonas aeruginosa) and Gram positive (Bacillus pumilus, Staphylococcus aureus) microorganisms by agar disc diffusion. Anti-biofilm studies were conducted and the biofilm inhibition percentage was calculated. SEM images clearly support the biofilm inhibition occurring to the microorganisms after the treatment with the nanoparticles. It was observed that the antibacterial and anti-biofilm efficacy of the samples increased with the size, concentration, and composition of the nanoparticles. Considering the morphological aspect, the nanoalloy structure showed better activity compared to the core shell structure. Thus it can be concluded that the size, concentration, composition and morphology are key factors that govern the antibacterial and anti-biofilm effectiveness of the synthesized bimetallic Au/Ag nanoparticles. To our knowledge and belief, this is the first work of its kind discussing all the controlling parameters together. This information could be incorporated while synthesizing nanoparticles for medical applications as coating substances.