title: Determination of cell/medium interfacial tensions from contact angles in aqueous polymer systems.
abstract: The contact angles on cell layers of a series of polymeric droplets from aqueous two-phase systems of dextran and poly(ethylene glycol) have been used to determine the critical or limiting interfacial tension for spreading on the cell layers. Test droplets of the denser dextran-rich phase were formed in the lighter poly(ethylene glycol)-rich phase. The interfacial tensions, gamma, between the phases were determined with the pendant drop method, and a linear relationship was found between gamma-1/2 and the cosine of the angle the droplets made with the cell layers (Good-Girifalco plot). We were thus able to determine the limiting or critical interfacial tension, gamma c, for spreading on the cell layers. The value of gamma c is a measure of the interfacial energy of the cell/bathing medium interface. Values of gamma c obtained by this method include the following: 0.65 and 0.84 microN . m-1 for human erythrocytes and neutrophils, respectively; 0.93 microN . m-1 for porcine pulmonary macrophages; 0.75--3.60 microM . m-1 for various transformed murine lymphoid cell lines, and 2.53 microN . m-1 for Balb/c murine spleen lymphocytes. Exposure to various agents has differing effects on gamma c. Concanavalin A reduces gamma c, and bacterial lipopolysaccharide increases gamma c of murine spleen lymphocytes. The calcium ionophore, A23187, increases gamma c of both porcine pulmonary macrophages and murine spleen lymphocytes. This new method provides a quantitative approach to the cell surface energy and hydrophobicity which are thought to play an important role in membrane-mediated phenomena and in cell adhesion.
mesh_terms: D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects; D003208:Concanavalin A / Q000494:pharmacology; D003911:Dextrans; D004912:Erythrocytes / Q000187:drug effects; D006098:Granulocytes / Q000187:drug effects; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D008214:Lymphocytes / Q000187:drug effects; D008264:Macrophages / Q000187:drug effects; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D011092:Polyethylene Glycols; D011108:Polymers; D013500:Surface Tension; D013552:Swine
chemical_list: D003911:Dextrans; D008070:Lipopolysaccharides; D011108:Polymers; D003208:Concanavalin A; D000001:Calcimycin; D011092:Polyethylene Glycols