Highly efficient antibody purification with controlled orientation of protein A on magnetic nanoparticles

and purified by affinity chromatography. To improve the surface area to volume ratio and increase the immobilization amount of protein A, chlorophenylsilane functionalized magnetic nanoparticles (CPTMS@MNPs) were prepared, which are smaller nanoparticles with an average diameter of 20 nm compared to commercial magnetic microparticles (Dynabeads) with an average size of 2.8 μm. The CPTMS@MNPs showed the enhancement of protein A immobilization and binding capacity to antibodies, being 11.5-fold and 7-fold higher than those of commercial Dynabeads, respectively. In addition, the CPTMS@MNPs retained about 80% of the initial protein binding capacity until the third stage of recycling. Therefore, protein A grafted CPTMS@MNPs may be useful for the industrial large-scale purification of antibodies.