Immobilization of Human Immunoglobulin G Antibodies Using Bifunctional Microparticles

Abstract

Immunoassays and immunosensors utilizing immunoglobulin G (IgG) antibodies have been widely employed in the biomedical field and even in forensics. The key to the production of immunoassays is the isolation of IgG antibodies, but there is no effective technique that can capture and purify IgG antibodies secreted by plasma B cells, the antibody producing cells in the human body. Particles in nano and micro scales are being developed for a wide range of applications in biosciences and biotechnology fields to improve the collection and purification of antibodies. A previous study demonstrated the ability of protein G coated microparticles to detect and collect very low concentrations of IgG antibodies, but there has been no study investigating the bifunctionalization of these particles to effectively target a specific plasma B cell and capture its secreted antibodies. Two options were considered for the application: bifunctionalized protein G particles (mixed particles), which are protein G particles conjugated with cell targeting antibody without spatial separation, and Janus particles, bifunctional microparticles with two physically and chemically distinct hemispheres. The purpose of this study was to compare the capability of mixed particles and Janus particles of different sizes (1 μm, 2 μm, 4 μm, and 7μm) to bind to plasma B cells and collect the secreted IgG antibodies. TIB (Tumor Immunology Bank) hybridomas, an immortalized plasma B cell line, were incubated with Janus microparticles and mixed microparticles for antibody collection. Through confocal microscopy, mixed particles and Janus particles demonstrated the ability to target B cells and collect secreted antibodies effectively and efficiently. Mixed particles showed greater antibody binding capabilities, whereas Janus particles showed greater cell targeting capabilities. Larger particles (4 μm and 7 μm) collected more antibodies but showed a lower cell binding affinity. Smaller particles (2 μm) collected less antibodies but showed a higher cell binding affinity. 1μm particles collected the least number of antibodies and showed the lowest cell binding affinity. Bifunctional microparticles have a possibility of becoming an innovative and effective tool for isolation and purification of antibodies that can enhance the development of vaccines and antibody therapy and benefit the biomedical and pharmaceutical fields.