Synthesis And Application Of Monodisperse Polystyrene Microspheres Based On Liquid Biochips

In this thesis, synthesis and application of functional monodisperse polystyrene microspheres based on liquid biochips is presented. The polystyrene microspheres are one of the excellent carriers of the liquid-chip sensing units. The introduction of carboxyl, amino, hydroxyl or other functional groups of biological, liquid components to the surface of polystyrene beads can be applied to sensor chips, so as to conduct high-throughput, high specificity analysis and test of nucleic acids, proteins and other biological macromolecules, such as screening tumor markers.The commercial polystyrene microsphere and its preparation method vary in parameter, regarding to different fields and purposes. At present, performance parameters of the commercial polystyrene microsphere are not ideal enough when building up the carrier of sensitive components of Liquid-Biochip. For example, there exists serious non-specific adsorption and poor activation effect for the domestic microspheres. On the other hand, the price of abroad ones from the company of Luminex,Bangs Laboratories,Spherotech,Duke Scientific and so on is usually much higher. All these factors make it not suitable for the development and long-term research of Liquid-Biochip.Chapter I of this thesis briefly introduces the development of liquid-chip and its application, and then lists and estimates various preparation methods of polystyrene microspheres. Finally we decide to synthesize the polystyrene microsphere with dispersion polymerization regarding to the requirement of applying the liquid-chip, and we specially focus on investigating the principle of synthesizing polystyrene microspheres with dispersion polymerization and its advantages and disadvantages.The main work of chapter II is the synthesis and characterization of the polystyrene microsphere. We focus on discussing a variety of factors including the effect of the amount of reactants, reaction time, reaction temperature, and stirring speed affecting the particle size and size distribution. And then we apply various methods to characterize the average size, size distribution, surface structure and pore size distribution of polystyrene microspheres. Eventually we find out the best conditions for the synthesis of 2.2μm mono-dispersed polystyrene microspheres.The carboxyl polystyrene microsphere is an important carrier for the liquid-chip. So its preparation and characterization are very important. In chapter III we compare the difference between copolymerization and seed modified dispersion polymerization. The surface of particles obtained from the latter method is rich in carboxyl groups. The carboxyl group can be activated to bind with the antibody. The microspheres binded with antibody can capture the target molecule which then binds with fluorescence molecules. We applied this method to detect the carcinoembryonic antigen (CEA) in chapter V, and aquire a good result.In chapter IV we describe the Preparation and Characterization of the amino polystyrene microsphere. First of all, we linked nitryl group to the surface of the blank microsphere with nitric acid, and then investigated the effect of the two deoxidize methods. Finally, we found out that the method of using sodium dithionite to reduce nitryl group into amino group can obtain dense monodispersed microspheres rich in surface amino groups.In chapter V we activated the amino microspheres with CDI and adipic dihydrazide (AADH) separately, characterized the activation effect with Ninhydrin color printing method, and then evaluated its ability coupling to the antibody with Coomassie brilliant blue (CBB) G250. Finally we detected human serum carcinoembryonic antigen proteins with the activated microsphere and a good result had been obtained.The result of this paper consummates a method of obtaining monodispersed, micrometer and dense surface structure polystyrene microspheres. And then we successfully bind the carboxyl and amino group to the surface of the microsphere. At last we detect the carcinoembryonic antigen (CEA) by carboxyl microspheres.