Magnetic poly (styrene/divinylbenzene/acrylic acid)-based hybrid microspheres for bio-molecular recognition

Polymer-iron hybrid magnetic microspheres with different carboxyl functionalisation for biomedical applications, thanks to suitable bio-recognition of the carcinoembryonic antigen (CEA), were prepared by the precipitation polymerisation of styrene-divinylbenzene-acrylic acid embedding iron oxide magnetic nanoparticles (~10 nm). The influence of the acrylic acid concentration in the final size of copolymer and, consequently, in the efficiency of the antibody coupling between the primary amino group (~NH₂) and the carboxyl functional groups (-COOH) in the polymeric surface were evaluated by varying monomers ratio with fixed content of magnetite nanoparticles. Particle size and morphology were investigated by scanning electronic microscopy and transmission electronic microscopy, as well as the saturation magnetisation values were measured in an electromagnet. The -COOH functionalisation and the covalent bounding of the antibodies, via detecting amino and carbonyl groups, were characterised by Fourier transform infrared spectroscopy. Regarding possible applications in molecular/cellular recognition and solid supports for immunoassays, efficient immobilisation of antibodies against CEA on particles surface via covalent bonding of the antibody and surface -COOH groups was demonstrated by immunochemistry techniques.