Synthesis and characterization of organosilica nanoparticles prepared from 3-mercaptopropyltrimethoxysilane as the single silica source

Novel organosilica nanoparticles made of 3-mercaptopropyltrimethoxysilane as the single silica source (MPS NPs) have been synthesized successfully by using a Stober method. The MPS NPs were well dispersed in solution and have unique surface properties such as thiol residues on the surface and reduced zeta potential compared with the nanoparticles made of tetraethoxysilane. The MPS NPs with fluorescent dye were synthesized by a method that deposited fluorescent dye on the silica network. The resulting MPS NPs with fluorescence were bright, nonaggregated in solution, and photostable. The fluorescence intensity and photostability of fluorescent MPS NPs were sufficient for detection as a single fluorescent particle using flow cytometry and fluorescence microscopy. Protein-modified MPS NPs were prepared easily by absorption and by maleimide coupling. In this paper, we demonstrate the usefulness of MPS NPs and their surface properties and discuss their advantages for biological applications.