A Study of the Strength of a Template Molecule—A Functional Monomer Interaction That Affects the Performance of Molecularly Imprinted Polymers and Its Application to Chiral Amplification

Abstract

A novel type of molecularly imprinted polymer (MIP), N-benzoyl-(S)-valine anilide-imprinted polymer (IP-2), was prepared using hydrogen-bonding interactions as a main force in the pre-polymerization step. The performance of the IP-2 was evaluated via batch procedure and compared with a (S)-valine anilideimprinted polymer (IP-1) that was prepared using an ionic interaction that is stronger than hydrogen bonding. Although both polymers showed a preferential adsorbability for (S)-amino acid derivatives, different performances were observed in terms of adsorbability and enantioselectivity. In addition, the IP-2 was able to recognize the enantiomer of a valine-derived chiral catalyst. This phenomenon was applied to a chiral amplification reaction, and a highly selective asymmetric Mannich-type amination was achieved using the combination of a racemic catalyst and a MIP.Key words molecularly imprinted polymer; chiral recognition; (S)-benzoyl amino acid anilide; asymmetric amplification Molecularly imprinted polymers (MIPs)1-3) have been energetically pursued in the field of molecular recognition, and various types of applications such as a stationary phase of HPLC, 4,5) solid-state extraction, 6) and chemical sensors 7,8) have been reported due to qualities such as synthetic simplicity, stability, and a high level of recognition selectivity.There are several methods for the preparation of imprinted polymers, including acid-base interaction, simple hydrogen bonding, dipole-dipole interaction, and hydrophobic interaction at the pre-polymerization step. Among these, the acidbase interaction 4,5,9) and/or hydrogen bonding 10,11) are mainly used due to the effectiveness of bonding strength in regards to the tailor-made construction of three-dimentional binding sites.Therefore, MIPs prepared using an acid-base interaction appear to show a higher level of performance than those without such an ionic interaction. However, unexpectedly, only a few reports 12) described the comparison of the different performances of MIPs between the presence of acid-base interaction and the absence of such a strong interaction. Therefore, it would be desirable to establish a new methodology, which would enable a convenient and precise comparison of the performance of MIPs that could lead to the development of a new type of MIP.We previously reported 13) the evaluation of basic (S)-amino acid anilide (such as (S)-1)-imprinted MIPs that were prepared using an acid-base interaction by batch procedure that allowed independent observation of adsorbability and selectivity, which were not precisely measured by a HPLC column system.In this paper we describe the evaluation of the performance of neutral (S)-N-benzoyl amino acid anilide (such as (S)-5)-imprinted MIPs, which were prepared in the presence of a weaker hydrogen-bonding interaction in the pre-polymerization step, by batch procedure. We also report a MIP with a (S)-N-benzoyl valine anilide cavity and its application to chiral amplification (Fig. 1). ExperimentalGeneral Ethylene glycol dimethac...

<p>Evaluation of Intestinal Absorption Mechanism and Pharmacokinetics of Curcumin-Loaded Galactosylated Albumin Nanoparticles</p>

“…Among these nanocarriers, bovine serum albumin nanoparticles (BSA NPs) are widely used for the effective drug delivery7,8 because of their non-toxicity, non-immunogenicity, biocompatibility and high water-solubility 9. Meanwhile, BSA with a long half-life can help the drugs to improve the blood drug concentrations for a relatively longer time 10. In addition, BSA has many functional carboxylic and amino groups, which can provide various binding sites to drugs.…”