Antimicrobial Synergistic Effect Between Ag and Zn in Ag-ZnO·mSiO(2) Silicate Composite with High Specific Surface Area

Antimicrobial materials are widely used for inhibition of microorganisms in the environment. It has been established that bacterial growth can be restrained by silver nanoparticles. Combining these with other antimicrobial agents, such as ZnO, may increase the antimicrobial activity and the use of carrier substrate makes the material easier to handle. In the paper, we present an antimicrobial nanocomposite based on silver nanoparticles nucleated in general silicate nanostructure ZnO·mSiO(2). First, we prepared the silicate fine net nanostructure ZnO·mSiO(2) with zinc content up to 30 wt% by precipitation of sodium water glass in zinc acetate solution. Silver nanoparticles were then formed within the material by photoreduction of AgNO(3) on photoactive ZnO. This resulted into an Ag-ZnO·mSiO(2) composite with silica gel-like morphology and the specific surface area of 250 m(2)/g. The composite, alongside with pure AgNO(3) and clear ZnO·mSiO(2), were successfully tested for antimicrobial activity on both gram-positive and gram-negative bacterial strains and yeast Candida albicans. With respect to the silver content, the minimal inhibition concentration of Ag-ZnO·mSiO(2) was worse than AgNO(3) only for gram-negative strains. Moreover, we found a positive synergistic antimicrobial effect between Ag and Zn agents. These properties create an efficient and easily applicable antimicrobial material in the form of powder.