Antibacterial Properties Of Nanometer Ag Composite Materials

Nano silver, such as the synthesized nanoparticle composites, can be widely used as biological antibacterial materials, medical materials, bacteriostatic agents, sewage treatment and other fields. It is well known that the antibacterial efficiency of the nanoscale silver is far superior to that of bulk silver. But the antibacterial efficiency of silver nanoparticles is decided by its radius, shape, distribution, etc. Theoretically, the smaller the radius of silver nanoparticles is, the higher the antibacterial efficiency is. However, small Ag nanoparticles with high surface energy tend to aggregate into big particles, which could deteriorate their unique chemical properties and induce loss of overall performance. Therefore, the stability of Ag nanoparticles is critical to their practical applications in nanoscience and nanotechnology.In order to solve the problem of easy reunion, monodisperse zirconia(ZrO2) and cuprous oxide(Cu2O) microspheres were served as the carriers to deposit homogeneously dispersed silver nanoparticles on their surface, resulting in the formation of Ag@Cu2O and Ag@ZrO2.Monodisperse spherical ZrO2 were prepared via sol-gel method using zirconium tetrabutoxide as the precursor of ZrO2, the Ag seeds were attached to the surface of the ZrO2 spheres by reducing the Sn2+ ions that were physically adsorbed on the surface of ZrO2 spheres with a small amount of AgNO3. The Ag seeds tethered on the surface of the ZrO2 served as a nucleation site for the growth of Ag nanoparticles to form Ag@ZrO2 composites via further reduction of Ag+ by formaldehyde to yield Ag0.Monodisperse Cu2 O colloidal spheres were produced by a sol-gel reaction. Procedure for Cu2 O spheres was formed immediately after the introduction of N2H4 in the Cu(NO3)2 aqueous solution, The Ag@Cu2O composite sphere with core–shell structure were prepared by photodeposition route.Both of the Ag@ZrO2 and Ag@Cu2O were characterized by transmission electron microscope(TEM), X-ray diffraction(XRD) and ultraviolet visible spectrum(UV-vis). gram-positive and gram-negative bacteria were used as testing strains to evaluate the antibacterial performance of Ag@ZrO2 and Ag@Cu2O nano-composite materials and their antibacterial mechanism was discussed. and their antibacterial activity against gram-positive(Staphylococcus aureus) and gram-negative(Escherichia coli) was also studied. The results indicate that the inhibitory rate against S. aureus and E. coli of the them is 95.5% and 99%, respectively, when the Ag is 0.6 mg/mL. Therefore, they can be used in daily life and medical practice as ideal antibacterial material.