Biosynthesis of Gold Nanoparticles and Gold/Prodigiosin Nanoparticles with Serratia marcescens Bacteria

This paper presents the biosynthesis of gold nanoparticles and gold/prodigiosin nanoparticles from the bacterium , Serratia marcescens. The intra- and extra-cellular synthesis of gold nanoparticles is shown to occur over a range of pH and incubation times in cell-free extracts and biomass of Serratia marcescens that were reacted with 2.5 mM tetrachloroauric acid (HAuCl 4 ). The formation of gold nanoparticles was recognized initially via color changes from yellow auro-chloride to shades of red or purple in gold nanoparticle solutions. UV–visible spectroscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and dynamic light scattering were also used to characterize gold nanoparticles produced within a range of pH conditions. The results show clearly that the production of gold nanoparticles from cell-free extracts require shorter times than the production of gold nanoparticles from the biomass. The implications of the results are also discussed for the processing of gold nanoparticles and gold prodigiosin nanoparticles for localized cancer treatment.