Mechanisms Assisting Or Impeding Adhesion in Biological Systems

Book excerpt: Intimate molecular contact at joint interfaces is essential for the extremely localized surface forces to result in adhesion exceeding the cohesive strength of the joined materials. Liquids, however viscous, are perhaps a more important class of adhesives in biology than in any other field. Attention is focused on the spreading of well-defined liquids over rigid or coherent phases of potential biological interest. The contact angle (T) of liquids on solids provides an inverse measure of liquid spreading. Rectilinear plots of cos T vs liquid surface tension (L) define the critical surface tension of wetting (Lc) for each solid. Direct, simple correlations exist between Lc and solid surface composition. Wetting and adhesion can be completely changed by adsorbed films, even monolayers; adsorbed water, for example, can markedly decrease Lc. Wettability properties and Lc concept are pertinent to current adhesional and biomedical problems. Coupling agents have a potential role in bioadhesion. (Author).