A Mussel Adhesive Protein Fused with the BC Domain of Protein A is a Functional Linker Material that Efficiently Immobilizes Antibodies onto Diverse Surfaces

Abstract The efficient immobilization of antibodies onto solid surfaces is vital for the sensitivity and specificity of various immunoassays and immunosensors. A novel linker protein, BC‐MAP, is designed and produced in Escherichia coli by genetically fusing mussel adhesive protein (MAP) with two domains (B and C) of protein A (antibody‐binding protein) for efficient antibody immobilization on diverse surfaces. Through direct surface‐coating analyses, it is found that BC‐MAP successfully coats diverse surfaces including glass, polymers, and metals, but the BC domain alone does not. Importantly, antibodies are efficiently immobilized on BC‐MAP‐coated surfaces, and the immobilized antibodies interact selectively with their corresponding antigen. Quartz‐crystal‐microbalance analyses show that BC‐MAP has excellent antibody‐binding ability compared to that of BC protein on gold surfaces. These results demonstrate that the MAP domain, with uniquely strong underwater adhesive properties, plays a role in the direct and efficient coating of BC‐MAP molecules onto diverse surfaces that lack additional surface treatment, and the BC domain of BC‐MAP contributes to the selective and oriented immobilization of antibodies on BC‐MAP‐coated surfaces. Thus, the BC‐MAP fusion protein could be a valuable novel linker material for the facile and efficient immobilization of antibodies onto diverse solid supports.