Preparation of bioactive nanotitania ceramics with biomechanical compatibility

Targeting neural stem cells with titanium dioxide nanoparticles coupled to specific monoclonal antibodies

Aiming to characterize the use of biomaterials in cancer therapy, we took advantage of the n-type semiconductor properties, which upon irradiation excite their electrons into the conduction band to induce photoelectrochemical reactions generating oxygen reactive species (ROS). Indeed, photoactivated TiO(2) nanoparticles have been shown to kill in vitro either bacteria or tumor cells in culture following UV irradiation, as a consequence of the ROS levels generated; the killing was highly effective although devoid of specificity. In this report, we have directed the TiO(2) nanoparticles to particular targets by coupling them to the monoclonal antibody (mAb) Nilo1, recognizing a surface antigen in neural stem cells within a cell culture, to explore the possibility of making this process specific. TiO(2) nanoparticles generated with particular rutile/anatase ratios were coupled to Nilo1 antibody and the complexes formed were highly stable. The coupled antibody retained the ability to identify neural stem cells and upon UV irradiation, the TiO(2) nanoparticles were activated, inducing the selective photokilling of the antibody-targeted cells. Thus, these data indicate that antibody-TiO(2) complexes could be used to specifically remove target cell subpopulations, as demonstrated with neural stem cells. The possible applications in cancer therapy are discussed.

Bioactive nano-titania ceramics with biomechanical compatibility prepared by doping with piezoelectric BaTiO(3)

Piezoelectric BaTiO(3) was employed as a crystal growth inhibitor additive for the preparation of bioactive nano-titania ceramics in this study. It is found that the additive could significantly inhibit nano-titania ceramic crystal growth during the pressureless sintering process. This inhibitory ability has great effects on the mechanical properties and bioactivities of the nano-titania ceramics, making it possible to obtain bioactive nano-titania ceramics with mechanical properties analogous to human bone. In this study, the crystal grain sizes of the nano-titania ceramics ranged from 18 to 68nm and the particle sizes ranged from 187 to 580nm by changing the additive content from 1% to 20%. The elastic modulus of the nano-titania ceramics ranged from 6.2 to 10.6GPa, which is analogous to that of human bone, by adjusting the additive content. The piezoelectric properties of the additive also showed the enhancing effects on the bioactivity of the nano-titania ceramics, which made the osteoblasts proliferate faster on the nano-titania ceramics in cell culture experiments. It might be a potential way to prepare bioactive nano-titania ceramics with biomechanical compatibility by using BaTiO(3) as a crystal growth inhibitor.