Surface-modified zirconia nanoparticles include zirconia nanoparticles and surface-modifying ligands attached to the zirconia nanoparticles. The ligand includes a hydroxamate functionality, and either a reactive group or an oligomeric group. Reactive groups include chain transfer groups or photoinitiator groups. Oligomeric groups include poly(meth)acrylate or poly(meth)acrylamide groups. Articles can be prepared that include the surface-modified zirconia nanoparticles in an organic matrix.