Synthesis And Evaluation Of Molecularly Imprinted Polymers Using α-(3-benzoylphenyl) Propionic Acid As Template

In recent years there has been a growing interest in the field of molecular imprinting.Molecular imprinting is a method to prepare polymers with recognition site of desired and predetermined selectivity.Molecularly imprinted polymers(MIPs) are prepared by copolymerizing functional and cross-linking monomers in the presence of a molecular template.After the removal of the template,the synthesized MIPs possess micro-cavities with a three-dimensional structure complementary in both shape and chemical functionality to that of the templates,and are able to rebind the templates.They have been successfully used in many fields,such as separation processes(chromatography,capillary electrophoresis,solid-phase extraction and membrane separations),immunoassays,antibody mimics,sensors,catalysis and artificial enzymes.There has been an increasing interest in the synthesis of molecularly imprinted polymers in non-covalent imprinting processes and a large variety of different chemical compounds have been successfully used as molecular templates in this processes,including both organic-based materials and inorganic ones.However,experimental data have demonstrated that non-covalent molecularly imprinted polymers exhibit a heterogeneous binding sites distribution.Heterogeneity also complicates the characterization of the ability to accurately characterize the binding properties of MIP's and how to evaluate the heterogeneity accurately is regarded more and more important.The classical method of preparing MIPs is bulk polymerization followed by grinding to particles.They are irregular,polydisperse and usually include a large portion of fine particulate mmerial.Extensive sieving and sedimentation to achieve a narrower size distribution and to remove fine particles make time and labor wasting.So many methods have been developed to directly prepare nanoscopic MIP's (nanoMIP's),such as suspension polymerization,precipitation polymerization,and emulsion polymerization et al.However,precipitation polymerization which is a easy and effective method has attracted considerable interest and played an important role in the area of preparing MIPs.With medicineα-(3-benzoylphenyl)propionic acid as molecular template,we polymerized a series of MIPs with different synthesize conditions in a one-stage reaction by precipitation polymerization,and studied the characteristic of MIPs.The results as follows:1 We polymerized a series of MIPs with different synthesize conditions by precipitation polymerization,The control blank polymers(BPs)were prepared using an identical procedure but in absence of the template.Equilibrium binding experiments was used to investigate the binding ability to template molecule,and the results reveled that the MIPs showed specific binding affinity toα-(3-benzoylphenyl) propionic acid.The adsorbing experiments indicated that the imprinted polymer particles possessed higher affinity to template molecule than the non-imprinted polymer particles.2 The polymerization conditions which influence the recognition of the polymers were investigated.Including the choice and composition of functional monomers,the choice and composition of mixed functional monomers,the mole ratio of template molecule,functional monomers and cross-linker,et al.With the UV spectrophotometer,optimum polymerization condition was obtained as follows:the mole ratio ofα-(3-benzoylphenyl)propionic acid(template molecule)/AA(functional monomers)/ EDMA(cross-linker)is 1:4:20,with 4575μL acetonitrile(porogenic solvent)and 0.0144g AIBN(initiator)will be optimized prepared under 60℃for 48 hours.3 The method of removing template molecule that influence the recognition of the polymers was investigated,which includes soxhlet apparatus and centrifugal separator associated with ultrasonic apparatus.We found that using the two methods synthetically can reach an ideal wash porpuse.4 There were two sorts of bingding-site or one bingding-site in the polymers by Scatchard spot.The sorption capacity and equilibrium isotherms for BPA onto BPA-imprinted polymers were estimated using Freundlich equilibrium models.The affinity distribution corresponding to the Freundlich isotherm was used to extract binding parameters for BPA- imprinted polymers.The affinity of the MIPs has been evaluated by apparent imprinting efficiency(E_ia)and imprinting efficiency(E_i),the result indicated that E_i can describe the specific binding of the BPA to the MIPs effectivly. In conclusion,we prepared MIPs with different synthesize conditions by precipitation polymerization,and studied the characteristic of MIPs systematically. This work is helpful for a preparation of MIPs in recognition under the molecular level.The method is simple and convenient,meanwhile,it is significant in the application of MIT in the separation and enrichment of BPA in complex samples,for example,blood.