Study On The Preparation Of BSA Coated Magnetic Microspheres By High Pressure Homogenization And It’s Application In Magnetic Lateral Flow Immunochromatography Assay

Magnetic microspheres coated with biological macromolecules have good water solubility, low non-specific adsorption, good biocompatibility, and have a variety of reactive functional groups(such as-COOH,-NH2, etc.), which can be coupled with bioactive substances(such as antigens, antibodies, enzymes, etc.). Magnetic microspheres can be easily separated and guided under the applied magnetic field, so they are widely used in the field of drug targeting, enzyme immobilization, cell separation, disease diagnosis etc..In this paper, bovine serum albumin coated magnetic microspheres(SPIO@BSA) were prepared by high pressure homogenization. The preparation conditions were optimized through the Plackett-Burman and Box-Behnken experimental design. The optimized conditions of High pressure homogenization were as follows: the preparation condition(A) was 0.44, the preparation condition(B) was 140, the preparation condition(C) was 2.2, the preparation condition(F) was 10000, the preparation condition(G) was 30, the preparation condition(J) was 600, the preparation condition(H) was 25, and the preparation condition(K) was 1. Transmission electron microscopy(TEM) and dynamic light scattering(DLS) showed that SPIO@BSA was spherical and monodispersed with average hydrodynamic diameter 245.8±3.4 nm and PDI 0.199±0.031. Vibrating sample magnetometer(VSM) demonstrated the saturation magnetization of obtained SPIO@BSA was 35.3 emu/g, suggesting they were superparamagnetic and had good magnetic response. Thermal gravimetric analysis(TGA) showed the magnetic content of SPIO@BSA was 62.0%, the content of BSA was approximately 28.4%. The surface carboxyl group content of SPIO@BSA was 0.14 mmol/g detected by Conductance titration.Clenbuterol monoclonal antibody(mAbCLE) and recombinant hepatitis B e antigen monoclonal antibody(MceAb) were labeled to SPIO@BSA respectively. Indirect competitive magnetic lateral flow immunochromatography assay was used to detect clenbuterol, the IC50 was 0.16 ng/m L and 0.09 ng/mL by optical colorimetric and magnetic signal detection assay respectively. Double antibody sandwich magnetic lateral flow immunochromatography assay was used to detect the recombinant hepatitis B e antigen, the IC50 was 19.9 ng/m L and 24.8 ng/m L by optical colorimetric and magnetic signal detection assay respectively. So SPIO@BSA can be applied in competition and sandwich method, the two main kinds of magnetic lateral flow immunochromatographic assays, have broad application prospects in the field of disease diagnosis, food safety and environmental monitoring etc.