Single step sol-gel made silver chloride on Titania xerogels to inhibit E. coli bacteria growth: effect of preparation and chloride ion on bactericidal activity

We report the antibacterial efficacies of silver and/or silver chloride containing titania xerogels synthesized with modified single step sol-gel methods against Escherichia coli bacteria. As the silver loading in TiO2 increases, the amount of the xerogel required to inhibit the growth of the bacteria decreases and also we found that pure TiO2 was not bactericidal. Among modified single step sol-gel methods used in this study, the additional HCl treatment sol-gel route III was very effective to obtain only AgCl crystallites in TiO2. Based on viable cell count method, 0.125 g/L of 29%Ag/TiO2 (made with HNO3 sol-gel route I) was enough to inhibit the growth of E. coli whereas 0.6 g/L of 29%Ag/TiO2 (made with the additional HCl treatment sol-gel route III) was required. However, antibacterial activity of 29%Ag/TiO2 (made with HNO3 sol-gel route I) after 6 usages was the same as 29%Ag/TiO2 (made with the additional HCl treatment sol-gel route III).