[Show abstract][Hide abstract] ABSTRACT: Singlet oxygen is a very important reactive oxygen species (ROS) involved in peroxidation of olefins and polymers, as well as in clinical photodynamic therapy treatments of tumors. Previously, it was reported that singlet oxygen can be formed via sensitization by spherical metal nanoparticles upon photo-excitation of the surface plasmon resonance (SPR) bands. In this paper, we report that sensitization and formation of singlet O 2 is strongly dependent on the morphologies of gold and silver nanostructures. For example, singlet O 2 can be generated via photo-irradiation and sensitization of silver decahedrons and silver triangular nanoplates, but not by silver nanocubes and gold decahedrons. The sensitization patterns of silver and gold nanoparticles are the reverse of each other. In the case of gold nanorods, singlet O 2 can be generated via photo-excitation at the longitudinal SPR band, but not by excitation at the transverse SPR band. The controlling factors for such a morphology dependent singlet O 2 sensitization will be discussed. Furthermore, we also demonstrate in vitro morphology dependent sensitization behaviour of silver nanoparticles in the photodynamic cancer treatment. Our results indicate that metal nanoparticles with certain morphologies are potentially very promising dual functional nanomaterials with capabilities of simultaneously serving as near infrared (NIR) activatable photodynamic therapy and photothermal therapy reagents for cancer treatments.
[Show abstract][Hide abstract] ABSTRACT: Improving on organic photosensitizers: The photoexcitation of metal nanoparticles results in the formation of singlet oxygen and its phosphorescence emission (see picture). As the nanoparticles are resistant to both photoinduced and enzymatic degradation and also have impressively high extinction coefficients, these findings may have an impact on techniques for the generation of singlet oxygen in biological settings.