Eco-Friendly and Temperature Dependent Biosynthesis of Gold Nanoparticles Using the Bacterium Pseudomonas aeruginosa: Characterization and Antibacterial Activity

In this paper we report the biological synthesis of gold nanoparticles (GNPs) by the reduction of gold ions using a suspension and supernatant of P. aeruginosa. The biosynthesis method was straightforward and yielded good results without using toxic chemicals. The size distribution of the gold nanoparticles synthesized by P. aeruginosa at higher temperatures was larger than that synthesized at lower temperatures. The GNPs morphology was isotropic at various temperatures. With an increase in the temperature, the stability of the GNPs decreased. The absorption and fluorescence spectra accorded well with the size distribution of the particles, with the nanoparticle size increasing as the absorption and fluorescence increased too. The optical properties of the GNPs observed in the study accorded well with the scanning electron microscopy (SEM) observations. The visible photoluminescence (PL) around 435 nm indicated the possible use of the obtained colloids, which consisted of GNPs and capping biomaterial, in therapeutic applications. Moreover, the synthesized GNPs showed good antibacterial activity toward E. coli indicating their potential in biological applications.