A mussel adhesive protein fused with the BC domain of protein A is a functional linker material that efficiently immobilizes antibodies onto diverse surfaces

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. Quartzcrystal- microbalance analyses show that BC-MAP has excellent antibodybinding 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.