A new synthesis method for bright monodispersed core-shell colored silica submicron particles

Abstract In this paper, we aimed to develop a two-step approach for highly efficient synthesis of bright core-shell colored silica submicron particles (core-shell colored SiO 2 SMPs) by coupling organic reactive dyes onto silica submicron particle (SiO 2 SMPs). C.I. Reactive Blue 21 was selected as model dye to synthesize a core-shell blue silica submicron particle (core-shell blue SiO 2 SMPs). 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane (3APTMS) and C.I. Reactive Blue 21 were grafted simultaneously on the surface of particles in the aqueous solution to produce bright blue SiO 2 SMPs. The effect of the amount of 3APTMS and C.I. Reactive Blue 21 on preparation of blue SiO 2 SMPs was studied. To prevent dye on blue SiO 2 SMPs from leaking, core-shell blue SiO 2 SMPs were prepared in a pre-hydrolyzed Stöber system. Scanning Electronic Microscopy (SEM) and Dynamic Light Scattering (DLS) were used to character the SiO 2 SMPs, blue SiO 2 SMPs, and core-shell blue SiO 2 SMPs. The results indicate that the blue SiO 2 SMPs and core-shell blue SiO 2 SMPs synthesized under the optimal conditions with regular morphology and good dispersibility. Coupling efficiency of the C.I. Reactive Blue 21 was as high as 89.2% (the quality of dye coupled was about 70 mg/g SiO 2 ). In the same way, six other different colored SiO 2 SMPs were also prepared by introducing different color organic reactive dyes on SiO 2 SMPs. The bright monodispersed core-shell colored SiO 2 SMPs is promising to be used as sensitive and reproducible maker in immunoassay. Graphical abstract A one-step approach for the high efficiently coupling of reactive dyes onto SiO 2 SMPs in an aqueous solution to synthesize monodispersed colored SiO 2 SMPs was designed. The hydrolysis and condensation of 3APTMS and dye coupling were preceded at the same time. After modification and coloration, a silica protection layer was grown onto the colored SiO 2 SMPs to prevent the dye leakage and to make the colored SiO 2 SMPs be pure silica surface.