Preparation of magnetic polymer microspheres with reactive epoxide functional groups for direct immobilization of antibody

Monodisperse magnetic polymer microspheres with epoxide functional groups have been developed through ex situ swelling and diffusion process. Poly(glycidyl methacrylate-co-divinyl benzene) (poly(GMA-co-DVB)) microspheres were prepared by cross-linking precipitation polymerization of GMA and DVB monomers without the use of surfactants and stabilizers. The microspheres were subsequently swollen in chloroform in the presence of oleic acid-coated iron oxide nanoparticles (IOs). The size of poly(GMA-co-DVB) microspheres can be controlled by varying the concentration of DVB cross-linker. Based on FTIR, XRD, and vibrating sample magnetometer (VSM) analysis, IOs were successfully entrapped in poly(GMA-co-DVB) microspheres. For a constant IO feed, increase in DVB content resulted in the decrease in the IO loading. It was found that the reactive epoxide functional groups of the microsphere's surface can covalently conjugate with monoclonal antibody, specific to CD4 molecules expressed on CD4+ lymphocytes, which was confirmed from flow cytometry. Thus, these microspheres are promising to be used in various biomedical applications including diagnosis, and monitoring of human diseases.

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► Monodisperse magnetic particles have been prepared by swelling and diffusion process.
► The particles exhibited superparamagnetism at room temperature.
► Epoxide groups on the surface allow for covalent attachment of biomolecules.
► Antibody was attached on particles without the signs of denaturation or degradation.