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.