Adsorption of plasma proteins onto anticoagulant polystyrene derivatives: a fluorescence study

Synthesis and anticoagulant activity of polyureas containing sulfated carbohydrates

Polyurea-based synthetic glycopolymers containing sulfated glucose, mannose, glucosamine, or lactose as pendant groups have been synthesized by step-growth polymerization of hexamethylene diisocyanate and corresponding secondary diamines. The obtained polymers were characterized by gel permeation chromatography, nuclear magnetic resonance spectroscopy, and Fourier transform infrared spectroscopy. The nonsulfated polymers showed similar results to the commercially available biomaterial polyurethane TECOFLEX in a platelet adhesion assay. The average degree of sulfation after reaction with SO₃ was calculated from elemental analysis and found to be between three and four −OSO₃ groups per saccharide. The blood-compatibility of the synthetic polymers was measured using activated partial thromboplastin time, prothrombin time, thrombin time, anti-IIa, and anti-Xa assays. Activated partial thromboplastin time, prothrombin time, and thrombin time results indicated that the mannose and lactose based polymers had the highest anticoagulant activities among all the sulfated polymers. The mechanism of action of the polymers appears to be mediated via an anti-IIa pathway rather than an anti-Xa pathway.

Interaction of poly(sodium vinyl sulfonate) and its surface graft with antithrombin III

Poly(sodium vinyl sulfonate) (PVS) was found to be 1/14 times as active as heparin in inducing the conformational change and activation of antithrombin III. The conformational change of antithrombin III was investigated in terms of the intrinsic fluorescence of tryptophan residue, the extrinsic fluorescence using 1,6-diphenyl-1,3,5-hexatriene as fluorescent probe, and Fourier-transform infrared spectroscopy. It was evident in the experiment using 2,4,6-trinitrobenzene sulfonate that PVS elicited the activity of antithrombin III by interacting with amino groups of the protein as does heparin. Sodium vinyl sulfonate was graft-polymerized onto polyetherurethane (PEU) film that was treated with glow discharge in advance. PVS-grafted PEU film adsorbed antithrombin III easily and, like ungrafted PVS, induced conformational change and activation of antithrombin III. However, the mechanism of interaction of the PVS graft with antithrombin III did not seem to be completely the same as that of ungrafted PVS in solution.

Selective binding of plasmin in the presence of excess plasminogen by certain anionic polystyrene resins

Contact of plasminogen with sulfonate or sulfonyl-glutamate derivatized polystyrene resins has previously been reported to lead to the formation of an active single-chain form of the plasminogen (Kichenin-Martin et al., Thrombosis Research, 52, 469-478, 1988). Attempts to duplicate this finding revealed instead that these polymers selectively adsorb active plasmin and thus remove it even in the presence of a great excess of plasminogen. Under optimum conditions 4.0 mg/mL plasminogen containing 3% plasmin was freed of one half of this contaminant by exposure to 6-9 mg of dry resin per mL in a batch mode. Neither ordinary polystyrene nor Dowex nor Sephadex cation exchange resins displayed these properties. The separation is based on the more rapid binding of plasmin to the active resins and is thus kinetically controlled.