Size-dependent antimycobacterial activity of titanium oxide nanoparticles against Mycobacterium tuberculosis

Nanobiotechnology has offered new approaches for drug delivery and for the development of medicines against microbial infections including the deadly multidrug-resistant tuberculosis (MDR-TB). The present study deals with the antimycobacterial activity of titanium dioxide (TiO2) nanoparticles against Mycobacterium tuberculosis. Initially, TiO2 nanoparticles were synthesized from titanium(iv)oxysulfate (TiOSO4) solution using the sol-gel method. The shape and size of the TiO2 crystals were analyzed using TEM and SEM and were found to be spherical and 16 nm respectively, thereby indicating their morphology. Moreover, the XRD pattern confirms that the prepared TiO2 nanoparticles were anatase as well as being tetragonal and FTIR spectra show the stretching vibrations of Ti-O and Ti-O-Ti. Further, the TiO2 nanoparticles were shown to exhibit excellent size-dependent antimycobacterial activity against Mycobacterium tuberculosis, M. bovis and Mycobacterium sp. in a concentration dependent manner (10-100 mu g mL(-1)). Confocal laser scanning microscopic analysis also confirmed that the TiO2 nanoparticles inhibit the biofilm formation of all three tested mycobacteria. The metabolic activity of mycobacteria was decreased up to 3-4 fold with an increase in the concentration of the TiO2 nanoparticles hence affecting the biofilm formation. Moreover, the TiO2 nanoparticles were less toxic (>25%) against normal lung bronchus cells at 100 mu g mL(-1) after 24 h treatment revealing that the nanoparticles are less toxic in nature. Taken together, these results showed that the TiO2 nanoparticles can be a potential biofilm agent against mycobacteria.