Selective adsorption of proteins to their ligands covalently immobilized onto microfibers

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.