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Staphylococcus aureus is one of the major causes of skin and soft tissue infections. In this study we compared the antimicrobial activity of two different TiO2 nanoformulations against Staphylococcus aureus. We synthesized TiO2 nanoparticles of approximately 80 nm diameter and TiO2 nanowires of approximately 100 nm diameter. Both nanoformulations possess anti-microbial activity; were non-hemolytic and cytocompatible. However, the anti-staphylococcal activity of TiO2 nanowires was better than the nanoparticles. In broth culture, growth of S. aureus was only partially inhibited by 2% and 4 wt% TiO2 nanoparticles and completely inhibited by TiO2 nanowires till 24 h. TiO2 nanowires treated S. aureus cells exhibits diminished membrane potential than nanoparticle treated cells. The anti-microbial properties of both TiO2 nanoformulations were validated using ex vivo porcine skin model which supplements the in vitro assays. Anti-bacterial activity of the TiO2 nanowires were also validated against multi drug resistant pathogenic strains of S. aureus, showing the clinical potency of the TiO2 nanowires compared to its nanoparticles.

The present paper reports a simple route to fabricate high surface area anatase TiO 2 mesoflowers from electrospun TiO 2 -SiO 2 composite nanostructures. Electrospun fiberand rice-shaped TiO 2 -SiO 2 composite nanostructures upon treatment with concentrated alkali (NaOH) under hydrothermal conditions (180 C) result in chemical transformation of the TiO 2 and in situ etching of SiO 2 to give sodium titanates. The sodium titanate upon acidification followed by a low temperature sintering (180 C) results in 3D TiO 2 mesoflowers. The material is found to be superior to the commercial P-25 in photocatalysis.

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A rice-shaped TiO2-ZnO composite was prepared by electrospinning a mixture comprising the precursors of TiO2 and ZnO in polyvinyl acetate polymer dissolved in N,N-dimethyl acetamide. The electrospun nanofibers upon heat treatment in air resulted in collapse of the continuous fiber morphology and the formation of the rice-shaped TiO2-ZnO composite. The TiO2-ZnO composite was then treated with dilute acetic acid under hydrothermal conditions to etch ZnO from the TiO2-ZnO composite to get coral-shaped anisotropic TiO2. The structural anisotropy of TiO2 produced by the selective etching of ZnO resulted in a high surface area of 148 m(2) g(-1) for the TiO2. The initial and final materials were characterized by scanning electron microscopy, transmission electron microscopy, Raman and XPS spectroscopies, powder X-ray diffraction and BET surface area measurements. The utility of the anisotropic TiO2 in photovoltaics and photocatalysis was explored. Dye-sensitized solar cells fabricated using the TiO2 showed a conversion efficiency of 6.54% as against 4.8% for a control experiment with the rice-shaped TiO2. The anisotropic TiO2 also showed good photocatalysis in the degradation of methyl orange dye and phenol.

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We report a simple synthesis route for producing ultrafine porous TiO 2 nanofibers ($10 nm diameters) from electrospun rice-shaped TiO 2 nanostructures. The rice-shaped TiO 2 obtained by annealing the as-spun TiO 2 -PVAc composite nanofibers was treated with concentrated alkali (with KOH under hydrothermal conditions) followed by acid treatment and low temperature sintering. The alkali treatment produces the titanate (K 2 Ti 3 O 7 ) which undergoes exchange of ions (protons) during the acid treatment resulting in H 2 Ti 3 O 7 . The heat treatment of the protonated titanate (H 2 Ti 3 O 7 ) results in their conversion to ultrafine TiO 2 (titanate-derived TiO 2 ) nanofibers. The rice-shaped TiO 2 and the titanate-derived TiO 2 nanofibers were characterized by SEM, TEM, XRD, XPS, Raman and BET measurements and the latter has $2.5 times higher surface area than the former. The TiO 2 nanofibers showed superior photocatalytic applications than the commercial P-25 TiO 2 .