Correlation study between molecular structure of sesquiterpene lactones and the selective adsorption performance of molecularly imprinted polymers

Abstract

We preliminarily report that the structure of template molecules and target components correlates with the selective adsorption performance of molecularly imprinted polymer (MIPs) in sesquiterpene lactones. Template molecules involved three categories of sesquiterpene lactones with distinct ring systems: 5-mem lactone ring atractylenolide III, 7-mem lactone ring dehydrocostus lactone, and 10-mem lactone ring costunolide lactone, of which the conformations were verified by variable-temperature (1)H NMR spectroscopy. Reciprocal MIPs were prepared by precipitation polymerization and employed as selective sorbents in the columns of solid phase extraction (SPE). These columns were further used for enriching the mixed adsorption solution of sesquiterpene lactone ingredients and reference components. Finally, the extract of Radix Aucklandiae, a Chinese medicine herb, was used to verify the efficiency of this method. Our results demonstrate that the steric conformational stability of molecules is associated with the selective adsorption of their corresponding MIPs. We have further observed that the maximum adsorption capacity occurs when the target molecule conformation is consistent with that of the template molecule. The addition of more hydrophilic groups correlates with weaker adsorption of MIPs. Our findings provide important information to help guide the selection of appropriate template molecules for synthesis of MIPs with specific adsorption.

Keywords: Molecular structure; Molecularly imprinted polymer; Selective adsorption performance; Sesquiterpene lactones; Variable-temperature (1)H NMR spectroscopy.