Nanoarchitectures of titania (TiO₂) have been widely investigated for a number of medical applications including implants and drug delivery. Although titania is extensively used in the food, drug and cosmetic industries, biocompatibility of nanoscale titania is still under careful scrutiny due to the conflicting reports on its interaction with cellular matter. For an accurate insight, we performed in vitro studies on the response of human dermal fibroblast cells toward pristine titania nanotubes fabricated by anodic oxidation. The nanotubes at low concentrations were seen to induce toxicity to the cells, whereas at higher concentrations the cell vitality remained on par with controls. Further investigations revealed an increase in the G₀ phase cell population depicting that majority of cells were in the resting rather than active phase. Though the mitochondrial set-up did not exhibit any signs of stress, significantly enhanced reactive oxygen species production in the nuclear compartment was noted. The TiO₂ nanotubes were believed to have gained access to the nuclear machinery and caused increased stress leading to genotoxicity. This interesting property of the nanotubes could be utilized to kill cancer cells, especially if the nanotubes are functionalized for a specific target, thus eliminating the need for any chemotherapeutic agents.

The abundance and low cost of sodium potentially enable application of sodium ion batteries for grid-scale energy storage. Consequently, anode materials with high power, long lifespan, and safe operation are highly desired. In this work, we successfully fabricate black K₂Ti₆O₁₃ nanowires as an anode material that exhibits the desired properties. The black K₂Ti₆O₁₃ nanowires are prepared via a hydrothermal method followed by post calcination and final hydrogen plasma treatment. The black K₂Ti₆O₁₃ anode delivers a high reversible capacity of 249 mA h g⁻¹. Impressively, it could sustain 20 000 cycles without apparent capacity fade. The first-principles calculation results suggest that the electrical conductivity of K₂Ti₆O₁₃ would be improved while the sodiation energy barrier could be reduced after introducing oxygen vacancies.