Fluorescent silica nanoparticles (FSNPs), amino-modified fluorescent silica nanoparticles (NH₂-FSNPs) and amino-modified fluorescent silica nanoparticles connecting with antibody have been synthesized in this paper. High-resolution transmission electron microscopy (HR-TEM), atomic force microscopy (AFM), Zeta potential, IR, fluorescent microscope and confocal fluorescent microscope were used to characterize these three types of nanoparticles. FSNPs are monodisperse in aqueous solution and NH₂-FSNPs tend to aggregate since the modification could alter the surface Zeta potential and form hydrogen bonding between amino groups on the surface of FSNPs, but these particles could disperse well again when NH₂-FSNPs connecting with antibodies further, the reason is the pH value of buffer solution was proper for NH₂-FSNPs to disperse well in the liquid, and amino groups on particles surface have been involved in the connection with antibodies. The NH₂-FSNPs showed good specificity and stability as they were used to recognize mesenchymall stem cells (MSCs) through CD44 on cell membrane. The fluorescent light emitted from NH₂-FSNPs was strong and it was easy to observe the target cells by microscopy. The study in this work has provided excellent examples for NH₂ modification, antibody connection and cell detection application by using FSNPs.

Key words: fluorescent silica nanoparticles, amino modification, disperse property, CD44