A stereocomplex platform efficiently detecting antigen-antibody interactions

Ultrathin poly(methyl methacrylate) (PMMA) stereocomplex films with macromolecularly double-stranded regular nanostructures were prepared by layer-by-layer assembly of isotactic and syndiotactic PMMAs on solid surfaces. Antibodies were immobilized through the Fc region-capturing protein A, which had been physically adsorbed on the complex film, and the binding of antigens to immobilized antibodies was quantitatively investigated by the quartz crystal microbalance technique. Greater amounts of protein A with native forms were adsorbed on the complex film than those on conventional single-component PMMA films. Antibodies with high target-binding activities were also immobilized on the complex film. A greater amount of antigens could be detected on the complex film. The activity of protein A was maintained on the complex for a long time even within a dried state. The mechanism for the preservation of protein native forms on the complex surface was speculated by analyzing the physical adsorption of proteins with various secondary structures. Stereocomplex films can be utilized as novel coating nanomaterials for efficiently detecting protein-protein interactions.