Contact activation of the intrinsic pathway of porcine blood plasma coagulation is shown to be a steep exponential-like function of procoagulant surface energy, with low activation observed for poorly water-wettable surfaces and very high activation for fully water-wettable surfaces. Test procoagulants studied were a system of oxidized polystyrene films with varying wettability (surface energy) and glass discs bearing close-packed self-assembled silane monolayers (SAMs) with well-defined chemistry consisting of 12 different terminating chemical functionalities. A monotonic trend of increasing coagulation activation with increasing water wettability was observed for the oxidized polystyrene system whereas results with SAM procoagulants suggested a level of chemical specificity over and above the surface energy trend. In particular, it was noted that coagulation activation by SAMs terminated with--CO2H was much higher than anticipated based on surface wettability whereas--NH3(+)-terminated SAMs exhibited very low procoagulant activity. SAMs terminated in--(CH2)2(CF2)7CF3 behaved as anticipated based on surface energy with very low procoagulant activity and did not exhibit special properties sometimes attributed to perfluorinated compounds. Quantitative ranking of the inherent coagulation activation properties of procoagulant surfaces was obtained by application of a straightforward phenomenological model expressed in a closed-form mathematical equation relating coagulation time to procoagulant surface area. Fit of the model with a single adjustable parameter to experimental measurements of porcine platelet-poor plasma coagulation time was very good, implying that assertions and simplifications of the model adequately simulated reality. Two important propositions of the model were that (1) the number of putative "activating sites" scaled linearly with procoagulant surface area, and (2) contact activation of the plasma coagulation cascade was catalytic in the sense that these activating sites were not consumed or "poisoned" by irreversible or slowly reversible protein adsorption during coagulation. An extension of the coagulation model proposed that procoagulant activation properties scale exponentially with the surface density of polar (acid-base) sites, which, in turn, was related to procoagulant wettability.

A study of blood protein adsorption to procoagulant surfaces utilizing a coagulation time assay, contact angles, Wilhelmy balance tensiometry, and electron spectroscopy (ESCA) is presented. Using a new contact angle method of measuring protein adsorption termed "adsorption mapping" it was demonstrated that protein-adsorbent surfaces were inefficient activators of the intrinsic pathway of the plasma coagulation cascade whereas water-wettable, protein-repellent surfaces were efficient procoagulants. Repeated use of fully water-wettable (spreading) glass procoagulants in the coagulation time assay demonstrated that putative "activating sites" were not consumed in the coagulation of platelet-poor porcine plasma. Furthermore, these procoagulant surfaces retained water-wettable surface properties after incubation with blood proteins and saline rinse. The interpretation of these observations was that plasma and serum proteins were not adsorbed to water-wettable surfaces. However, ESCA of these same surfaces revealed the presence of a thin protein layer. Wilhelmy balance tensiometry resolved these seemingly divergent observations by demonstrating that protein was "associated" with a bound hydration layer, but not formally adsorbed through a surface dehydration or ionic interaction mechanism.

Theory and practice of a new method of correlating surface energetics (wettability) with surfactant and protein adsorption properties from aqueous solution are introduced. The method quantified adsorption through an index comprised of solid-liquid interfacial tensions measured by contact-angle goniometry.This adsorption index was shown to have nomographic utility when plotted against surface wettability.The resulting graphical construction, termed an adsorption map, had physical boundaries that restricted index data to regions defining interfaced excess (adsorption) or depletion, allowing straightforward prediction of the surface wettability required to enhance or defeat adsorption. Adsorption mapping was shown to be applicable to both single-and multiple-component solutions of known or unknown chemical composition.Theoretical predictions were tested against results obtained with nonionic, anionic, and cationic surfactants of known chemical composition that exhibited different mechanisms of adsorption. Glass coverslips with or without a hydrophobic silane coating and oxidized polystyrene plaques served as test substrata. Adsorption mapping results were corroborated by the surface thermodynamic method of measuring adsorption by concentration-dependent contact angles. The surface spectroscopies ESCA and SSIMS were applied to obtain direct chemical evidence of strongly-adsorbed cationic surfactant to oxidized surfaces to provide additional confirmation of adsorption mapping results. A simple mathematical model of adsorption was presented that allowed interpretation of linear-like trends observed in the mapping of surfactants, purified proteins (human serum albumin and bovine 7-globulin), and heterogenous mixtures of blood proteins (fetal bovine serum and porcine plasma).