pH-sensitive uniform gel beads for DNA adsorption

Uniform gel beads 3 mm in diameter were obtained by the suspension polymeri zation of an amine functionalized monomer, N-3-(dimethyl amino)propyl-metha crylamide (DMAPM). The polymerization of DMAPM in the form of uniform dropl ets could be achieved at room temperature in an aqueous dispersion medium b y using Ca-alginate gel as the polymerization mold. In this preparation, po tassium persulfate/tetramethyl ethylenediamine and sodium alginate/calcium chloride were used as the redox initiator and the stabilizer systems, respe ctively. The crosslinked DMAPM gel beads exhibited pH-sensitive, reversible swelling-deswelling behavior. The uniform gel beads were also obtained by the copolymerization of DMAPM and acrylamide (AA) in the same polymerizatio n system. Although copolymer gel beads with higher pH sensitivities were ob tained with increasing feed concentration of DMAPM, the total monomer conve rsion decreased. Crosslinked DMAPM and DMAPM-AA copolymer gel beads were ut ilized as sorbents for DNA adsorption. The gel beads produced with higher D MAPM feed concentration exhibited higher equilibrium DNA adsorption capacit y. The DNA equilibrium adsorption capacities up to 50 mg DNA/g dry gel coul d be achieved with the crosslinked DMAPM gel beads. This value was reasonab ly higher relative to the previously reported adsorption capacities of know n sorbents. (C) 2000 John Wiley & Sons, Inc.