Preparation And Recognition Properties Of Molecularly Imprinted Polymer For Punicalagin

As a novel technique, Molecular Imprinting Technique (MIT) is becoming more and more popular. MIT is used to prepare a kind of polymer called Molecularly Imprinted Polymer (MIP) which has powerful recognition sites for certain molecules. The process of preparation is as follows:(1) the template molecules are mixed with monomers with appropriate functional groups which are arranged around the template by the covalent or non-covalent interaction between them. (2) Functional monomers and cross-linkers are co-polymerized. (3) The template molecule is removed by extensive rinsing after polymerization so that the cavities are left into the polymers which are complementary to the template in terms of size, shape, and functional groups. These cavities exhibit an effect of specialized recognition. MIT now has a great applied potential in separation, purification, immunoassay, enzyme mimic, bio-mimic sensor and other fields.In this paper, the purification of punicalagin using column chromatography was studied. The purified product was characterized by HPLC and MS; the punicalagin purity and yield of the extract are 85.3% and 64.62% respectively. Molecularly imprinted polymers (MIPs) for punicalagin were successfully prepared by precipitation polymerization using the purified punicalagin as template, acrylamide (AM) as functional monomer, ethylene dimethacrylate(EDMA) as the cross-linker, acetonitrile (ACN) as solvent, azoisobutyronitrile (AIBN) as initiator. The molecularly imprinted polymer was characterized by scanning electronic microscopy. The result of equilibrium adsorption experiments showed that the MIPs can adsorb the template molecule selectively, and have a high affinity to the template in comparison with the blank polymers (BPs). According to Scatchard analysis it is showed that two kinds of binding sites were formed in the MIPs. For the high affinity sites, the dissociation content Kd1 and the apparent maximum binding capacity Qmax1 are 5.104μmol/mL,242.629μmol/g, and for the low affinity sites, the dissociation content Kd2 and the apparent maximum binding capacity Qmax2 are 0.414μmol/mL,35.106μmol/g, respectively. The max adsorption of MIPs is 32.564μmol/g under the studied concentration. The selective adsorption experiment inferred that MIPs have a higher selectivity for punicalagin than for bisphenol-A.