Novel route towards large scale synthesis of bright, water dispersible core-shell fluorescent dye doped organosilicate nanoparticles

Development of stable, biocompatible and ultra-bright fluorescence agents can lead to highly sensitive and non-invasive tools to locate and monitor biological targets within complex systems, including the human body. The motivation of this research is to have an easily scalable method of synthesizing fluorescent dye doped core-shell organosilicate nanoparticles with excellent size uniformity and water dispersibility. Here, we report on the synthesis of such nanoparticles essentially through all wet chemical processes, combining the approach of polymer collapse to first synthesize the fluorescent cores followed by the well-known Stober´s process to grow conformal silica shells over nanoparticle cores. Such a core-shell approach is expected to significantly reduce dye leakage from the nanoparticles over long term storage thereby improving the reliability and biocompatibility of these nanoparticles. The synthesized nanoparticles were characterized to be within 15-20 nm size range and exhibited excellent long term stability when dispersed in aqueous solutions. Further, because of the small size of these nanoparticles, these nanoparticles were effectively internalized by biological cells through electroporation techniques.