Green Synthesis Of Nanosilver Particles Colloidal Sol And Its Antimicrobial Property

Using starch as the protective agent and glucose as reducing agent, nano-size silver particles colloidal sols have been green synthesized in the condition of ultrasonic irritation. The colloidal sols were characterized by ultraviolet-visible spectroscopy (UV-Vis), transmission electron microscope (TEM), X-ray powder diffractometer (XRD) and so on. The better preparation parameters are determined by experiments as follows:silver nitrate concentration is 0.1～0.15mol/L, the weight of starch to silver nitrate is 2:1, the glucose concentration is 0.4mol/L, reaction temperature is 70℃,300W ultrasonic power and the reaction time is 180 minutes. The colloidal sols have uniform particle size distribution, and the nanoparticles are spherical and its average diameter is about 25nm.The antimicrobial property of prepared colloidal sols was tested using impregnation cultivation. The result shows that the prepared nano-silver sol has good antimicrobial effect to the E. coli (98%) and S. aureus (86%). The nanosilver-PE blend antimicrobial plastic films were prepared through blending a certain amount of nanosized silver colloids with polyethylene (PE) plastic granules and then blowning film. Compared with pure PE film, the properties of the nanosilver-PE blend antibacterial plastic films such as Transmittance, Haze, Tensile properties, Tear roperties and Contact angle all have no significant change and can meet the actual demand for package. Besides, the nanosilver-PE blend plastic films have better antimicrobial property. The antimicrobial effect of the nanosilver-PE blend plastic film (the content amount of nano-silver is 85.6ppm) to E. coli is 95%, but the pure PE film has no antimicrobial effect. In order to study the fresh preservation of the the nanosilver-PE blend plastic film, the pears were packaged respectively using pure PE film and nanosilver-PE blend plastic film (the content amount of nano-silver is 85.6ppm). The results show that the drop of hardness, weight loss, total soluble solids and organic acid content of pears packaged by nanosilver-PE blend plastic film are lower than those of pears packaged by PE film.This illustrate that the nanosilver-PE blend plastic film has fresh preservation effect.