A titanium oxide nanoparticle includes anatase titanium oxide, and may be a nanofiber having a minimum dimension less than 200 nanometers and having an aspect ratio greater than 20:1. A titanium oxide nanoparticle including anatase titanium oxide may include a dopant metal and/or a dopant nonmetal, and may be in a form other than a nanosphere. A method of making nanoparticles includes heating a reaction mixture in an autoclave, where the reaction mixture includes a titanium source and a polar organic solvent.