CHEMICAL PREPARATION AND PROPERTIES OF SOME HIGH CONCENTRATED COLLOIDAL SILVER SOLUTIONS FOR ANTIMICROBIAL APPLICATIONS

Some stable colloidal silver solutions of 600-1700 ppm silver nanoparticles (AgNps) concentration by an original and efficient chemical synthesis method were prepared. This method is based on the reduction of an aqueous silver nitrate solution with a sodium borohydride solution in the presence of a stabilizer agent of anionic polyelectrolyte type namely poly(acrylic acid sodium salt). The synthesis was carried out in proper conditions relating to concentration, temperature, pH, dropping rate and stirring. The synthesized AgNps were characterized by various techniques like: UV-Vis spectrophotometry, Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS) and antimicrobial analyses. AgNps had a spherical shape and a maximum diameter of 32 nm indicated by TEM and DLS analyses. Moreover, the DLS analyses revealed a narrow grain size distribution of AgNps and a high stability of the solutions, showed by the zeta potential values. The antibacterial and antifungal tests proved that the prepared colloidal silver solutions have high antimicrobial properties.