Multidrug-resistant bacteria are a dangerous problem in healthcare. Developing new approaches to kill bacteria is, thus, important. Nanoparticles (NPs), for example, can have antibacterial effects. Titanium dioxide NPs can generate radicals under irradiation with light, which then oxidize and kill bacteria. However, such metal oxide NPs are usually prepared with high size variability, defects, or a tendency to agglomerate. This can reduce their effectiveness.

Carol López de Dicastillo, Universidad de Santiago de Chile and Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Santiago, Chile, and colleagues have developed a controlled synthesis of uniform, hollow TiO₂ nanospheres. The method is based on a combination of electrospinning and atomic layer deposition (ALD). The team first prepared spherical poly(vinylpyrrolidone) (PVP) particles by electrospinning. These particles were coated with Al₂O₃ and TiO₂ using ALD. Then they were calcined at 600 °C under to remove the PVP core.

The resulting hollow particles have an inner Al₂O₃ layer, which stabilizes the structure, and an outer TiO₂ shell. These layers are thin and provide a high surface area and good bioactivity. The nanospheres can kill a multidrug-resistant strain of bacteria under UV light. According to the researchers, they could also be used for photocatalytic purposes.

• Novel hollow titanium dioxide nanospheres with antimicrobial activity against resistant bacteria,
  Carol López de Dicastillo, Cristian Patiño, María José Galotto, Yesseny Vásquez-Martínez, Claudia Torrent, Daniela Alburquenque, Alejandro Pereira, Juan Escrig,
  Beilstein J. Nanotechnol. 2019, 10, 1716–1725.
  https://doi.org/10.3762/bjnano.10.167