Molecular recognition in template-imprinted cationic photopolymerized silicone microbeads

Molecular recognition phenomena have been studied in cationically polymerized microbeads. Cationic polymerization of a bis-epoxy silicone monomer by a diaryliodonium salt photoinitiator was found to occur fast enough to polymerize the droplets of an aerosol spray of the monomer, photointiator, and template in flight. Symmetric microbeads averaging 31 {dollar}mu{dollar}m in diameter were produced and captured by electrostatic precipitation. A series of reaction chambers were constructed to optimize the yield of usable microbeads. The effect of numerous functional groups on the rate of polymerization was examined. Nitrogenous bases were found to be detrimental to polymer bead formation, as were certain carboxylic acids. Use of template-imprinted microbeads as template-specific HPLC stationary phases gave inconclusive results due to problems associated with packing the columns.; Batch absorption studies indicated that beads imprinted with the morphine analog thebaine displayed {dollar}sim{dollar}2 to 4.3 times stronger molecular recognition properties for thebaine than did non-imprinted beads, with 1.3 to 4.1 {dollar}mu{dollar}mol re-binding sites per 1 g of beads. Both thebaine-templated and non-imprinted beads retained similar amounts of the thebaine derivative 17,18-Bis-(methoxycarbonyl)-6,14-ethenocodeine methyl ether, suggesting that the sites are thebaine-specific rather than generic micropores.