An improved class of fluorescent silica nanoparticles for indirect immunofluorescence detection of MCF-7 cells

Abstract In this work, we have developed an efficient method based on silica fluorescent dye-doped nanoparticles and second antibody for cancer cell labeling. The dye-doped silica nanoparticles were synthesized by the reverse microemulsion method with the conjugate of 3-aminopropyltriethoxysilane and rhodamine B isothiocynate. A PEG with flexible long chain as the bridge was introduced onto the surface of the nanoparticle via cyanogens bromide method. The second antibody, goat anti-rabbit IgG, was conjugated on the surface of the PEG-terminal modified silica fluorescent nanoparticles by covalent binding to the PEG linkers via the EDC/sulfo-NHS method. The concentrations of goat anti-rabbit IgG covering the nanoparticles were quantified via the Bradford method. The silica fluorescent nanoparticles functionalized with rabbit anti-MUC1 antibody were employed as bioprobes for the recognition of MUC1 protein in human breast carcinoma molecules MCF-7 cells. Compared with fluorescent dye labeled IgG, the fluorescent nanoprobes display dramatically increased photostability.