Synthesis of pH stable, blue light-emitting diode-excited, fluorescent silica nanoparticles and effects on cell behavior.

To date, delivery of light-emitting diode (LED)-activated compounds to cells and tissue remains a challenge. Silica-based materials possess good biocompatibility and have advantages of control of size and shape. Fluorescent silica nanoparticles (NPs) have been synthesized and used for applications such as cell tracking and tumor identification. Here, we report the synthesis and optimization of fluorescent silica NPs, which incorporate a naphthalimide dye with triethoxysilanes that are excited by the blue LED wavelength (LEDex NPs). The NPs can be imaged in the 420-470 nm wavelength, demonstrate a high quantum yield, are stable in a range of pH, and are taken into the cells. Therefore, these NPs represent a novel imaging technology for biomedical applications.