Novel fluorescent dye comprising metal oxide nanoparticles are prepared where the nanoparticles are as small as 3 nm or up to 7000 nm in diameter and where the dye is bound within the metal oxide matrix. In some embodiments the invention, novel dyes are covalently attached to the matrix and in other embodiments of the invention a dye is coordinate or ionic bound within the metal oxide matrix. A method for preparing the novel covalently bondable modified fluorescent dyes is presented. A method to prepare silica comprising nanoparticles that are 3 to 8 nm in diameter is presented. In some embodiments, the fluorescent dye comprising metal oxide nanoparticles are further decorated with functionality for use as multimodal in vitro or in vivo imaging agents. In other embodiments of the invention, the fluorescent dye comprising metal oxide nanoparticles provide therapeutic activity and incorporated therapeutic temperature monitoring.
