Green synthesis of polysaccharides-based gold and silver nanoparticles and their promissory biological activity

This paper demonstrates a green approach for the synthesis of gold and silver nanoparticles using polysaccharides extracted from macroseaweed as reducing agents. The formation of Au-NPs and Ag-NPs was confirmed by UV-Vis spectroscopy and Transmission Electron Microscopy (TEM). TEM analysis of both polysaccharides-based metallic nanoparticles surprisingly showed that the type of the polysaccharides (alginate or carrageenan) not only influence the morphology and the sizes of the nanostructures but also avoid the aggregation of them. The biological activity of these eco-friendly metallic nanoparticles was tested on two Gram-negative pathogenic organisms such as Pseudomonas aeruginosa and Salmonella Typhimurium, showing similar activity than those ones prepared using the well-known inorganic reducing agent, sodium citrate (SC). Futhermore, hemolytic activity was also tested showing that the polysaccharides-based metallic nanoparticles (Ps-MNPs) were less cytotoxic than the corresponding gold and silver nanoparticles prepared using SC. These results strongly suggest that these Ps-MNPs could be used as antimicrobial agents for the treatment of bacterial infections.