Synthesis of Fluorescent, Monodisperse, Colloidal Silica Particles

Abstract

The preparation of colloidal, fluorescently labeled silica particles by controlled hydrolysis and polycondensation of tetramethoxysilane (TMOS) in the presence of a silylated fluorescein derivative is described. Monodisperse particles with average radii of 80 nm and a narrow size distribution with a standard deviation lower than 8% are obtained using the seeded growth technique, whereas homogeneous nucleation yields particles with a bimodal size distribution. The apparent degree of labeling ranges from 5 × 10-8 to 2 × 10-6 mol equivalent of fluorescein per gram of silica, depending on the labeling procedure.