Extracellular biosynthesis of silver nanoparticles using fungi and their antibacterial activity

Abstract

Silver nanoparticles have particular properties that contribute to their very promising applications, novel in various fields of science, such as the development of biosensors, the diagnosis and treatment of cancer, the controlled release of drugs and the antimicrobial potential. The biological synthesis of nanoparticles is of great interest over other physical and chemical methods because the use of toxic chemicals and drastic reaction conditions are avoided. The extracellular biosynthesis using fungi could also make downstream processing much easier than the intracellular biosynthesis. One of the main applications of silver nanoparticles is their antimicrobial activity. Several studies have demonstrated the bactericidal properties of silver nanoparticles are different from silver ions, and that they are strongly influenced by their shape, size, concentration and colloidal state. In the present work, the ability of fungal strains from Uruguay to synthesize silver nanoparticles was studied. Eight fungi were able to synthesize nanoparticles. An extensive physicochemical characterization of the nanoparticles was carried out including ultraviolet-visible spectroscopy, transmission electron microscopy, dynamic light scattering, zeta-potential and gel electrophoretic mobility. According to the characterization and colloidal stability results, nanoparticles from three fungi were selected for antimicrobial activity assays. All nanoparticles were able to inhibit Escherichia coli growth, demonstrating their potential as effective antibacterial agent for use in biomedical applications.