Improved antimicrobial activities of biphasic titania nanowires against Gram-negative and Gram-positive bacteria

Abstract

This research focused on the synthesis of biphasic titania nanowires from commercially available anatase titania via hydrothermal method to improve its antimicrobial activity. The electron microscope scanning (SEM) showed that the titania nanowires structures were successfully synthesized with width varying from 17 to 96 nm and length from 0.7 to 8 μm. The titania nanowires have biphasic structure of brookite and anatase, as observed from the X-ray diffraction pattern. The band gap was calculated from the ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS) spectra at 3.3eV, which is between the range of pure anatase and pure brookite band gap. The crystallite size of the titania nanowires was calculated using the Scherer equation and showed a much smaller crystallite size compared to commercial titania. The antimicrobial activity of the titania nanowires was then investigated against gram-negative and gram-positive bacteria. They exhibited improved antimicrobial activity against the Gram-negative Pseudomonas aeruginosa and Escherichia coli along with Gram-positive Bacillus subtilis. Interestingly, their inhibition zone was comparable to the antibiotic tetracycline. Meanwhile, the commercial titania did not show any antimicrobial activity on any tested bacterial strains. The improved antimicrobial activity of the titania nanowires was attributed to its biphasic phase, small particle size, and its one-dimensional morphology.