Magnetic Microspheres Prepared By Reduction Self-assembly Used For Immunoassay

Magnetic microspheres?SPIO@BSA?prepared by superparamagnetic iron oxide nanoparticles?SPIO?coated with biomacromolecules BSA have several advantages,such as low non-specific adsorption,good biocompatibility and with active functional groups,which are easy to conjugate bioactive molecules.Simultaneously,magnetic microspheres can be separated and guided easily with external magnetic field.Thus,they are widely used in immune analysis,targeted drug,rapid cell separation,enzyme immobilization and other fields.In this paper,it is the first time that 3PM has been used as a reductant and then magnetic microspheres was successfully prepared through reduction self-assembly method,which was further applied in magnetic immunochromatography.The main research contents and conclusions include:1)Albumin nanoparticles were reproduced successfully by reduction self-assembly method according to literatures.The 3PM was firstly used as a reductant to prepare BSA nanoparticles.2)SPIO with thermal decomposition method coated with BSA?SPIO@BSA^T?was prepared by reduction self-assembly according to above optimal conditions.The magnetic particles were collected,and the particle size was 223.1 nm and the PDI was 0.148 by dynamic light scattering?DLS?.Electron microscopy demonstrated that SPIO@BSA^T was spherical.TG analysis showed that magnetic content was 61.53%.Significantly,SPIO@BSA^T can remain stable when saved in pH 8.0 tris buffer,MBW and 0.1%BSA solution.All results indicated that BSA was not easy to dissociate from SPIO.On the other hand,SPIO@BSA^T owned better magnetic separation property and with low non-specific adsorption.Furthermore,the two preparation methods of immunomagnetic microspheres?SPIO@BSA^T-IgG?were performed.Compared to EDC/NHS method,the one-step method by adding IgG in the preparation process had higher activity.Finally,One-step method was used to conjugate AFP monoclonal antibody and then AFP was detected by double antigen sandwich magnetic immunochromatography.The IC₅₀ was 7.53 IU/mL by optical colorimetric method.3)SPIO with chemical coprecipitation coated with BSA?SPIO@BSA^C?was prepared by reduction self-assembly method.The particle size was 350⁵50 nm.The magnetic microspheres were collected at 15 min,and the particle size was 543.1 and the PDI was0.128.Electron microscopy demonstrated that SPIO@BSA^C was spherical.TG analysis showed that magnetic content was 58.23%.Magnetic chromatography was performed after conjugating antibody,results suggested that although SPIO@BSA^C-IgG was active,there was blocking at the bottom of the NC film because of the large particle size of SPIO@BSA^C,so it was not suitable to be used in magnetic immunochromatography.