Luminescent mesoporous silica nanoparticles for biomedical applications: Synthesis and characterization

Abstract

We report the synthesis and detailed characterization of intrinsically/lable-free luminescent mesoporous silica nanoparticles (L-MSN), which may have useful biomedical applications. These particles were prepared by modified Stober's method followed by calcination. By optimizing the ratio of (3-aminopropyl triethoxysilane) APTS to tetraetthoxysaline (TEOS), particles with size ~ 43 nm and size dispersion ~ 12% were obtained. The luminescence of L-MSN is suggested to be due to the formation of carbonaceous compounds, giving particles yellowish brown color, during the process of calcination at optimum temperatures ~ 400 °C. Interestingly, our studies suggest that these carbonaceous impurities are carbon dots (C-Dots) and fluorescence anisotropy decay measurements indicate C-Dots as integral part of L-MSN. Luminescent properties of L-MSN were found to be stable as a function of pH as well as long time light exposure. Our results suggest that L-MSN may be explored for biomedical imaging as well as drug delivery applications.