Surface-Grafted, Molecularly Imprinted Polymers Grown from Silica Gel for Chromatographic Separations

Imprinted polymers were grafted successfully from silica gel via atom-transfer radical polymerization. Measured binding kinetics for protected amino acid templates onto the molecularly imprinted polymers on silica gel (MIP-SG) and MIPs prepared by conventional solution-phase synthesis demonstrated that the MIP-SG had improved mass-transfer properties and also had higher binding capacity per unit mass of polymer. In addition, a high-performance liquid chromatography column packed with MIP-SG showed higher column efficiency and better resolution for the enantiomers, Boc- l -tryptophan and Boc- d -tryptophan, relative to a column packed with the conventionally prepared MIP. When Boc- l -Trp was used as the template molecule during MIP-SG synthesis, the column packed with the resulting polymer retained the Boc- l -Trp to longer elution time than the Boc- d -Trp. This order of elution was switched when Boc- d -Trp was used as template.