TiO2 nanostructures - a double edged sword: current progress on their role in stem cells' differentiation, cancer therapy, and their toxicity issues.

Titanium dioxide (TiO₂)-based nanostructures have wide applications in cosmetics, toothpastes, pharmaceuticals, coatings, papers, inks, plastics, food products, textiles, and many others. Recently, they have also been found to have huge potential as stem cells' differentiation agents as well as stimuli-responsive drug delivery systems in cancer therapy. In this review, we present some of the recent progress in the role of TiO₂-based nanostructures toward the above-mentioned applications. We also present recent studies on the toxicity issues of these nanomaterials and the mechanisms behind the toxicity issues. We have reviewed the recent progress of TiO₂-based nanostructures on their stem cells' differentiation potentials, their photo- and sono-dynamic capabilities, as stimuli-responsive drug delivery systems, and finally their toxicity issues with mechanistic understanding on the same. We believe that this review will help researchers be aware of the latest progress in the applications as well as few toxicity issues associated with TiO₂-based nanostructures, which will help them design better nanomedicine for future applications.