Preparation of Co3O4 Nanoparticles in a Lyotropic Liquid Crystal Medium and Their Application in Anti-bacterial, Anti-cancer and Catalytic Activities

Preparation of Co3O4 nanoparticles (NPs) via a chemical reduction method at room temperature in a lyotropic liquid crystal (LLC) medium is described. A mixture of triton X-100 and water in the ratio 2.1:2.9 (wt%) exhibited LLC having a hexagonal structure in the temperature range of 25-29 degrees C. The NPs were prepared in this medium by reducing cobalt(II) chloride hexahydrate (CoCl2<middle dot>6H(2)O) using sodium borohydride (NaBH4) resulting in nearly spherical particles having a size of similar to 100 nm. The LLC medium facilitated a controlled growth of the NPs and also provided stabilization for the NPs by preventing their aggregation. The anti-bacterial activity of the particles indicated a significant activity towards gram-negative bacteria. Anticancer activity against breast cancer cell line MCF-7 showed an impressive IC50 value of 30.8 mu g/mL. Additionally, the efficiency of the Co3O4 NPs as catalyst for the reduction of 4-nitrophenol and degradation of a dye named methylene blue was evaluated; the apparent rate constant values calculated for these reactions were 1.8 x 10(-2) min(-1) and 3.1 x 10(-2) min(-1) respectively. Besides, particles displayed efficient activity till 5(th) cycle.