Adhesive substrates for fibronectin

In order to promote cell attachment, fibronectin must first undergo activation by a suitable substrate. In this study, 52 materials have been surveyed for their ability (a) to bind fibronectin, (b) to activate the cell‐adhesive property of fibronectin, and (c) to support the growth of cells. Many plastics, polysaccharides, metals, and ceramics were found to support cell growth as well as the fibronectin‐dependent attachment of cells. Several other substrates have been identified that were inactive in promoting either cell attachment or growth. Hydrophobic substrates were found to be active in fibronectin activation, whereas hydrophilic substrates were found to be inactive. Since fibronectin binds to substrata of extremely varied chemical composition, it is clear that the binding of fibronectin to such substrata is nonspecific in nature. Since protein pretreatment of all substrata, except collagen and poly(L‐lysine), abolished the physical binding of fibronectin, the binding of fibronectin to artificial substrata is probably ascribable to a nonspecific hydrophobic protein‐substratum interaction. In contrast, several lines of evidence indicate that the interaction between fibronectin and collagen displays biological specificity. Poly(hydroxyethylmethacrylate)(poly(HEMA)), which has previously been shown to be nonadhesive for cells, is demonstrated here to be unique in its inability to bind fibronectin. Addition of one part per million of an adhesive polymer to poly(HEMA) permits fibronectin binding to occur.