Design And Characterization Of Affinity Polymer Latex Microspheres By Soap-free Emulsion Polymerization

Affinity polymer latex microsphere is a kind of functional polymer microsphere, which could immobilize component of the couple on its surface or attach to specific site on cells.Via bioaffinity of biospecific couples,these functional microspheres could collect their partners onto the latex microspheres,so realize the separation of the target molecules.Affinity polymer latex microspheres are composed of two parts, the carrier microspheres and the biomolecules immobilized on the support.Affinity polymer latex microspheres have the common advantages of functional polymer microspheres,i.e.,stable dispersions,large specific surface areas as well as versatile properties.In addition,these smart latex microspheres have several particular features, such as well mechanical performance,non-specific adsorption,high activity,excellent biology compatibility,easy to recovery and repetitive to use,friendly to environment, etc.So affinity polymer latex microspheres exhibited potential application for bioseparation,antibody identification,DNA diagnosis as well as evaluation the efficiency of medicine.In this study,poly(styrene-co-glycidyl methacrylate)(PSG)latex microsphere was at first prepared by the soap-free emulsion polymerization with batch wise operation mode in the presence of 2,2'-azobis(2-amidinopropane)dihydrochloride as an initiator.Then,the surface of the above microsphere was modified by the grafting reaction between the epoxy groups of its surface and the amino groups of amino-terminated polyethylene glycol[NH₂(PEG)_nNH₂](5≤n≤20)with different carbon chain length or 1,6-diaminohexane to reduce the steric hindrance and side interaction of the surface of supported microspheres.Finally,the adsorption of protein onto the surface modified polymer latex microspheres was studied.This paper focus on the study of the preparation and characterisation of affinity polymer latex basic microspheres by soap-free emulsion polymerization and the effect factors of the surface modification and protein adsorption.The first chapter:documentation review.This part mainly introduced the definition,features of affinity polymer latex microspheres,the domestic and international research progress,potential application,and so on.The different preparation methods of the affinity polymer latex microspheres were emphatically compared,the meaning of the surface modification of the functional microspheres,the characteristic and grafting method of the polyethylene glycol and its derivative spacer arm molecules were summarized.Furthermore,the immobilization of the biomolecules and the adsorption theory of protein were discussed.The second chapter:preparation of affinity polymer latex microspheres by soap-free emulsion polymerization.In this part,poly(styrene-co-glycidyl methacrylate) latex microsphere was prepared by soap-free emulsion polymerization with batch wise operation mode in the presence of 2,2'-Azobis(2-amidinopropane) dihydrochloride as an initiator.The diameter of PSG latex microsphere thus produced was about 300nm and had a well monodispersity with particle size distribution index U＜1.05,the concentration of epoxy groups on the surface of the microsphere could reach to 3mmol/g.The stability,surface morphology,particle size and concentration of surface functional groups of the latex microspheres were characterized.The kinetics of soap-free emulsion polymerization and the effects of polymerization factors,i.e.,polymerization temperature,the ratio of comonomers and the concentration of functional groups,type and concentration of initiator and the feed operation mode were emphatically examined.The third chapter:surface modification of the affinity polymer latex microspheres.In this chapter,The spacer arm molecules(i.e.,amino-terminated polyethylene glycol)were successfully grafted on the surface of the epoxy-containing latex microsphere.The grafted yield of NH₂(PEG)₉NH₂ onto the surface of microsphere was approximately 67%and the water content was increased by 50% compared to unmodified microsphere.According to the comparison result, amino-terminated polyethylene glycol[NH₂(PEG)_nNH₂]should be an ideal spacer arm molecule due to its excellent biocompatibility and proper grafted yield.The grafted yield was strongly dependent on the chain length of the spacer arm molecules and the optimum length of the spacer arm molecules was existed for immobilized biomolecule.In addition,both the amount and the mobility of the epoxy groups on the microsphere surface were key factors to the grafted yield.The fourth chapter:study on the adsorption of protein on the surface modified polymer latex microspheres by amino groups.In this study,bovine serum albumin (BSA)was as the model protein and the surface modified latex microspheres was as the support material.The behavior of protein adsorption onto the latex microspheres was investigated and the effect factors of the adsorption reaction,i.e.,adsorption time and temperature,initial concentration of protein solution,ionic strength were emphatically studied.The fifth chapter:conclusions.In this part,the research of all steps were generalized and the main conclusions were also obtained.