Novel fluorescent poly(glycidyl methacrylate) – Silica microspheres

• Monodispersed poly(glycidyl methacrylate) microspheres were coated with silica.
• Silica was formed both on the surface and inside the pores of the microspheres.
• Presence of silica increased the thermal stability of the microspheres.
• Good biocompatibility of microspheres with human Jurkat T cells was detected.
• The microspheres exhibited red and green fluorescence.

Monodisperse macroporous poly(glycidyl methacrylate) (PGMA) microspheres were prepared by multiple swelling polymerization using a modified Ugelstad method. The outer and inner parts of PGMA microspheres were coated with silica (SiO2) using tetramethyl othosilicate (TMOS) and trimethoxy(methyl)silane (TMMS) to produce PGMA&SiO2 and PGMA&MeSiO2 hybrid particles, respectively. In order to introduce amino groups, the microsphere surface was functionalized with (3-aminopropyl)diethoxy(methyl)silane (APDMS) and (3-aminopropyl)triethoxysilane (APTES) resulting in PGMA&SiO2NH2 and PGMA&MeSiO2NH2 particles, respectively. The particles were characterized by SEM and TEM coupled with energy dispersive X-ray analysis (EDAX) and FT-IR spectroscopy to determine morphology, particle size, polydispersity and the presence of functional groups. Elemental and thermogravimetric (TGA) analyses were used for determination of the formed SiO2. Moreover, specific surface areas of the hybrid microspheres were determined by dynamic adsorption of nitrogen. In biological experiments, PGMA, PGMA&SiO2 and PGMA&SiO2NH2 microspheres demonstrated good biocompatibility in vitro, since no significant increase in the amount of dead (Trypan Blue) human Jurkat T cells was observed when the microsphere concentrations in the medium increased from 0.1 to 1 μg/ml. The microspheres exhibited red and green fluorescence. The former increased in the order PGMA < PGMA&SiO2 < PGMA&SiO2NH2. The PGMA&SiO2NH2 microspheres did not significantly swell at pH 7.0–9.5. They were capable of binding biomacromolecules, e.g., bovine serum albumin by adsorption or Dextran Blue by covalent binding.

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