Selective and high-capacity binding of immunoglobulin G to zirconia nanoparticles modified with phosphate groups

High-performance and cost-effective purification is necessary for the development of antibody drugs. This study found that nanoparticles of zirconia modified with phosphate groups selectively adsorb immunoglobulin G (IgG) antibodies against serum proteins with high adsorption capacity. The IgG antibodies collected from the zirconia nanoparticle surfaces retain their molecular conformation. Importantly, zirconia nanoparticles have the highest affinity for human IgG antibodies among tested mammalian IgG antibodies. The affinity for human IgG subclasses is in the order IgG3 > IgG1 > IgG2, which contrasts with a conventional ligand (Protein A) that has a lower affinity for IgG3. Because zirconia nanoparticles are chemically and mechanically stable, they can be utilized for the purification of antibody drugs not only in batch methods but also in chromatography as a process upstream or downstream of Protein A chromatography and even as an alternative process.