Multifunctional core-shell nanoparticles as highly efficient imaging and photosensitizing agents.

Here we report the preparation of a novel multifunctional core-shell nanocomposite material that contains a nonporous dye-doped silica core and a mesoporous silica shell containing photosensitizer molecules, hematoporphyrin (HP). This architecture allows simultaneous fluorescence imaging and photosensitization treatment. The photosensitizer molecules are covalently linked to the mesoporous silica shell and exhibit excellent photo-oxidation efficiency. The efficiency of photo-oxidation of the core-shell hybrid nanoparticles was demonstrated to be significantly improved over that in the homogeneous solution. The mesoporous silica nanovehicle acts not only as a carrier for the photosensitizers but also as a nanoreactor to facilitate the photo-oxidation reaction. The doping of fluorescence dyes into the nonporous core endows the imaging capability, which has been demonstrated with cell imaging experiments. This approach could be easily extended to conjugate other functional regents if necessary. These multifunctional nanovehicles possess unique advantages in acting as nanocarriers in photodynamic therapy to allow simultaneous high-resolution targeting and treatment.