The outbreak of a deadly strain of Escherichia coli (E. coli) bacteria motivates us to conduct extensive research on the development of new bactericidal agents. Transition metal oxides (TMO) offer one possible disinfection strategy and are pursued due to a number of advantages, such as low cost, engineering control, tunability which is difficult with other approaches coupled with generation of less disinfection by-products than other methods. In this study, we will present a generation process of TMO nanocomposites through facile green-chemical approach. Several steps are shown as follows: (1) A complex between a metal ion and a ligand, that is the functional group of a protecting polymer, is formed in an aqueous solution; (2) The metal ion is reduced to a metal atom with a reducing agent; and (3) The metal atoms aggregate and grow into a nanoparticle.The effect of the nature and concentration of reducing agents have been evaluated. TMO-based disinfectants offer an effective approach in water purification. This discovery found that silver (Ag) decorated titania (TiO2) nano-composites displayed high potency at 2.5 ppm within 4 hr co-incubation, proved to be effective at 100 % inactivation. The composite disinfectant was effective against both Gram-negative and Gram-positive bacteria, Escherichia coli and Staphylococcus aureus. The mechanism of action is through nanocomposite catalysed photocatalytic oxidation and possible depolarization of the bacterial outer membrane, resulting in disinfection under visible-light conditions.

Green synthesis of nanocomposites used as effective bactericidal agents

247th National Meeting (2014)

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