Design of Functional Polymeric Microspheres for Bioseparations
Background:
Functionalized polymeric microspheres are of interest for applications in the biochemical/biomedical fields. Emulsion polymerization produces aqueous dispersions of 0.05-1.0 micron polymeric particles. By incorporating desired functional groups within the particle or on the particle surface, microspheres for a variety of applications can be synthesized. When a suitable functionality is contained on the surface of, and/or within, a polymeric microsphere, the particles can be used for a variety of applications including medical diagnostics, immunoassays, cell separation, drug delivery and chemical analysis. The nucleic acid bases are of particular interest because of their role in forming complexes between complementary bases through hydrogen-bonding interactions. Our ongoing research involves the design, synthesis and characterization of polystyrene microspheres functionalized with thymine to assess the potential of these new materials for bioseparation applications. The design and synthesis of the microspheres is done at Queen's University (M. Cunningham) while the characterization and functional testing is done at the University of Western Ontario (J. Puskas, A. Margaritis).
Research:
Emulsion polymerization is used to produce submicron polystyrene microspheres functionalized with thymine. Two possible approaches for covalently bonding the thymine to the polymer backbone are being examined. The first approach is to incorporate the thymine moieties into the polymerizable monomer vinylbenzyl thymine (VBT) that is copolymerized with styrene. The second approach is to copolymerize styrene with vinylbenzyl chloride, and then conduct a nucleophilic substitution of the chloride groups on the copolymer with thymine. Preliminary experiments at Queen's have demonstrated the feasibility of our approach. Crosslinked particles with 50 wt% styrene and 50 wt% vinylbenzyl chloride were subsequently treated with a thymine salt in DMF. Infrared (IR) spectroscopy analysis has verified conversion of ~85-90% of the chloride groups.
Precipitation polymerization is now also being used to synthesize monodisperse micron-sized particles that can be functionalized with thymine.
Structure of vinylbenzyl thymine
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