TiO 2 -x N x nanoparticles were prepared by employing the direct amination of 6−10-nm-sized titania particles. Doping on the nanometer scale led to an enhanced nitrogen concentration of up to 8%, compared to e2% in thin films and micrometer-scale TiO 2 powders. The synthesized TiO 2 -x N x nanocrystals are catalytically active and absorb well into the visible region up to 600 nm, thus exemplifying the use of a nanostructurebased synthesis as a means of producing novel photocatalytic materials.

The applicability of semiconductor QDs in photodynamic therapy (PDT) was evaluated by studying the interaction between CdSe QDs with a known silicon phthalocyanine PDT photosensitizer, Pc4. The study revealed that the QDs could be used to sensitize the PDT agent through a fluorescence resonance energy transfer (FRET) mechanism, or interact directly with molecular oxygen via a triplet energy-transfer process (TET). Both mechanisms result in the generation of reactive singlet oxygen species that can be used for PDT cancer therapy.