Selective adsorption of proteins to their ligands covalently immobilized onto microfibers

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Abstract
Following ozone oxidation of polyester microfibers of 3.5 μm average diameter and 0.83 m2/g specific area, the fiber surface was subjected to graft polymerization of acrylic acid and subsequently immobilized with serologically active proteins including Staphylococcus aureus protein A, a specific antigen, and a specific antibody. The immobilization reaction was mediated by a watersoluble carbodiimide, which allowed formation of a co‐valent linkage between the ligand proteins and the grafted poly(acrylic acid)chains. The yields of the immobilized ligand proteins were of the order of 1 mg/g fiber. Their binding affinity and capacity to respective specific proteins were studied in vitro from a buffered solution and serum. It was found that the specific proteins were selectively adsorbed with dissociation constants as low as 1× 10−6 M, suggesting the adsorption to take place through highly specific protein‐protein interaction. An addition of serum albumin did not significantly affect the specific binding, regardless of the ligand proteins. The binding capacity ranged from 1 × 10−13 to 1× 10−11 mol/cm2 primarily depending on the surface density of the immobilized ligands and the number of their binding sites per molecule. © 1995 John Wiley & Sons Inc.