Preparation And Properties Of Functional Polysilsesquioxane Fluorescent Microspheres

Fluorescent microspheres have been widely used in modern biochemical research, such as DNA detection, intracellular imaging and drug delivery system. In this article, a series of functionalized polysilsesquioxane microspheres were fabricated through a two-step acid-base catalyzed sol-gel method.First of all, thiol-functionalized monodisperse microspheres(PMPSQ) were prepared from y-mercaptopropyltrimethoxysilane (MPTMS). The effect of monomer concentration on the synthesis and the growth process of the microspheres were studied.Afterward, rhodamine-B doped poly(3-mercaptopropylsilsesquioxane)(RB-PMPSQ) fluorescent microspheres with narrow size distribution were synthesized in an aqueous solution with rhodamin B(RB) as the hydrolysis catalyst and the fluorescent dye at the same time, and then an ammonia solution was added to catalyze the condensation of silanol. The size of the microspheres (1.26-3.48urn) could be effectively controlled by tuning the MPTMS concentration. The RB-PMPSQ fluorescent microspheres showed good fluorescent properties and excellent photostability. The formation mechanism of the fluorescent microspheres was also proposed.Then, epoxy-functionalized and RB-doped fluorescent microspheres (RB-PEPSQ) were prepared from y-(2,3-epoxypropoxy)propytrimethoxysilane(EPTMS). The growth process and the effect of NH4OH and monomer concentration on the morphology and size distribution of the microspheres were discussed. The RB-PEPSQ fluorescent microspheres exhibited good fluorescent properties and photostability.In addition, bi-functionalized polysilsesquixane microspheres were also fabricated from hydrolytic co-condensation of MPTMS and vinyltrimethoxysilane (VTMS), methacryloxypropyltrimethoxysilane (MAPTMS) respectively. The effect of monomer ratio on the morphology and size of the microspheres was researched.