Study On The Properties Of L - Phenylalanine Molecularly Imprinted Polymers Based On β - Cyclodextrin Derivatives And Its Application

Cyclodextrin and its derivatives have a unique hollow truncated conestructure with good molecular recognition. They have been widely used in chiral separation, artificial enzyme, as well as food, medicine, analytical chemistry and many other fields. The molecularly imprinted polymers have the both advantages of biometric identification and chemical identification, and its selective recognition ability could be further improved by cyclodextrin molecularly imprinted polymer. So it is important that the cyclodextrin molecularly imprinted polymer can be applied to the chiral separation of racemic amino acid.On the basis of refering extensive relevant literatures, the chemical modified cyclodextrins and the molecular imprinted technique based on cyclodextrins were reviewed, and the various features and applications of the methods of separation of enantiomeric amino acids by high performance liquid chromatography (HPLC) were also summarized and discussed. On this basis, a series of molecular imprinted polymers (MIPs) were synthesize, which used L-Phennylalanine (L-Phe) as the resarech object. The synthetic condition optimized by the methods of single factor optimization and orthogonal design. Their recognition and selectivity properties were studied. The specific research works were carried as follows:1. Two new chiral functional monomers were synthesized. They were maleic acid monoester of β-cyclodextrin (MAH-β-CD) and (S)-N-(1-phenylethyl) acrylamide [(S)-PEA]. The MIP synthetic condition, including four functional monomers, the ratio of monomer and template, type of porogen solvents, the amount of crosslinker and polymerized methods, were optimized by the methods of single factor optimization and orthogonal design, respectively. The adsorption mechanism of the polymer was discussed, and the structure parameters were characterized. The results showed that the inclusion compounds of MAH-β-CD and L-Phe under the mole ratio of2:1could synthesized the effective molecularly imprinted polymer (MIP26), which was bulk imprinted with1mmol inclusion compounds, and10mL dimethyl sulfoxide as porogen solvent, in the presence of15mmol crosslinker. MIP26showed the good imprinting efficiency (QMIp/QNIp=1.598) and high adsorption capacity (Q=53.09mg/g). Then a HPLC method for determination and separation of L-Phe was established to study the selective recognition of MIP26. The selective factor of MIP26about L-Phe on phenylalanine racemates separation was2.602, showed excellent chiral separation ability. In the mixture of six aromatic amino acids, MIP26also expressed the potential selectivity.2. Acrylyl-β-cyclodextrin (A-β-CD) and methacryloyl-P-cyclodextrin (MA-P-CD) were synthesized as two new chiral functional monomers. The synthetic conditions of MIPs were optimized by orthogonal design. The experiments on the optimized MIP included discussing adsorption mechanism and characterizing structure parameters in details. The results showed that the inclusion compounds of A-β-CD and L-Phe under the mole ratio of2:1could be synthesized to effective molecularly imprinted polymer (MIP37). The MIP synthetic conditions were lmmol inclusion compounds,10mL isopropanol-water mixture (v/v,3:7) as porogen solvent, in the presence of5mmol crosslinker and bulk imprinting. MIP37showed the good imprinting efficiency (QMIP/QNIP=1-656) and high adsorption capacity (Q=48.35mg/g). In the applications of HPLC methord, MIP37showed excellent chiral separation ability between the DL-Phe enantiomers (selective factor of L-Phe,2.110) and expressed the potential of selectivity in the mixture of six aromatic amino acids. These experiments for chiral seperation of amino acids provided a favorable basis for future research.