http://www.cd-bioparticles.com/p/DiagNano™-Green-Fluorescent-Silica-Particles-20-μm_258_262_293_3920.html20 µm silica particles with fluorescence dye covalently bound in the silica matrix are availbale with green fluorescence (excitation: 485 nm, emission: 510 nm). These particles have a hydrophilic surface with terminal Si-OH bonds.