Synthesis, Characterization, and Use of New Solid and Hollow, Magnetic and Non-Magnetic, Organic-Inorganic Monodispersed Hybrid Microspheres

Abstract

New organic-inorganic hybrid microspheres composed of cores of micron-sized monodispersed polystyrene microspheres (1–6 µm diameter) and shells of silica or iron oxide (Fe304-magnetite) microspheres of substantially lower diameter (30–40 nm) were formed by seeded polymerization of Si(OEt)4 or iron salts, respectively, on polystyrene microspheres. Leaching of traces of the magnetic coating, or iron salts, from the magnetic polystyrene shells into the working solution was prevented by a further coating with silica microspheres. Non-magnetic and magnetic hollow silica microspheres were formed by burning off the organic polystyrene core of the silica coated non-magnetic or magnetic polystyrene microspheres. Hybrid micro-spheres with functional groups other than inorganic hydroxyls were prepared by reacting the silica-coated particles with co-alcoholic reagents and/or co-alkylsilane compounds such as SiR3(CH2) X; R = Cl, OCH3, OC2H5, etc.; n = 3−17; X = CH3, CN, CO2Me, ΦCH2C1, etc. Particles containing ω-hydroxyl or primary amine groups were prepared by interacting the silica surfaces with alkylalkoxysilane compounds such as Si(OEt)3(CH2)3CO2CH3 or Si(OEt)3(CH2)3NH2; or with trichloroalkylsilane compounds such as SiC13(CH2)3CO2CH3 or SiC13(CH2)3CN, followed by diborane reduction of the terminal ester or nitrile surfaces, respectively. Polyaldehyde derivatized microspheres were formed by reacting the co-amine derivatized particles with polyacrolein microspheres of approximately 60 nm. Immuno-magnetic microspheres were prepared by covalent binding of the desired antibodies to the polyaldehyde particles. Preliminary studies demonstrated the potential use of the immuno-magnetic micro-spheres for two purposes concerning male infertility: (1) The specific removal of anti-sperm antibodies and sperm cells containing anti-sperm antibodies from semen of infertile males in vitro and (2) the separation of sperm cells from epithelial cells.