Stduy On Synthesis Of Magnetic Particles For Immunoassay

Superparamagnetic particles have been widely used in immunoassay, such as magnetic microbead-based immunoassay, magnetic lateral flow immunoassay and so on. Currently, most of commercial magnetic particles are synthetised by monomer polymerization with the shortcomings that the number of groups at the surface are difficult to control, and as time go by, some monomers will fall off. Besides, it needs to use some blocking agents, such as BSA protein etc, to reduce the nonspecific adsorption.In this reaseach, the magnetic particles were synthetised by coating BSA to the original particles, which can not only provide reacting groups,but also get a low nonspecific adsorption.The crosslinking method and high temperature denaturation method were used respectively.In the crosslinking method, firstly, BSA proteins was absorbed to the surface of Fe3O4particles,then the absorbed proteins were crosslinked by EDC or G484to form a net which trapped the Fe3O4particles. The low nonspecific adsorption magnetic particles were get successfully and they could be used in the IgG detection by magnetic chemiluminescence immunoassay. But during the detection, the magnetic particles were easily aggregated, that not appeared in the magnetic particles synthetised by high temperature denaturation method.Water bath and microwave could all let the reaction solution to get a high temperature which denaturant BSA proteins to form a net.Through the characterization of TEM, FTIR, TG and the comparison of dispersibility of magnetic particles in different pH and salt concentration, the conclusion was getted that the microwave method could obtain magnetic particles with more proteins.Besides, using high temperature denaturation method, citric acid stabilized Fe3O4particles,which were obtained at the optimal conditions that pH was4.0,and mass ratio was one to two,could be coated by BSA proteins.After coupling with IgG, they could be used in the magnetic lateral flow immunoassay. The microwave method was proved to obtain magnetic particles with more proteins than the water bath method again, And its magnetic particles were more suitable for magnetic lateral flow immunoassay. In a word, the high temperature denaturation method using microwave to get protein coated magnetic particles for magnetic microbead-based immunoassay and magnetic lateral flow immunoassay was a first study.It provided a simple method for synthetising magnetic particles for immunoassay.