Heparin-poly preparation

Displacement by plasma of radiolabeled thrombin and radio-labeled thrombin-antithrombin III inactive complex from a heparinized surface was measured and found to be significant for example, removing 63% of the thrombin and 90% of the complex that could not be removed by phosphate-buffered saline alone. Heparin-poly(vinyl alcohol) (PVA) gel beads with a very low heparin release rate, prepared by acetal coupling of the heparin to the PVA, adsorbed thrombin and potentiated the inactivation of thrombin by antithrombin 111, as measured by both thrombin time and chromogenic substrate assays. 

The aim of this paper is to report the bonding of heparin on poly(ethylene terephthalate) films containing an acrylic hydrogel (pHEMA), the method of preparation of the support material and some of its properties. 

Passirani, C., L. Ferrarini, et al. (1999). Preparation and characterization of nanoparticles bearing heparin or dextran covalently-linked to poly(methyl methacrylate). J Biomater Sci Polym Ed 10(1) 47-62. 

PVPyrH Poly-4-vinylpyridine (PVPyr) prepared by conventional persulfate catalyzed polymerization was dissolved in ethyl alcohol or methyl Cellosolve (2 to 3% solution) for application to polyester film substances. These films adsorb heparin from solutions of sodium heparin to produce anticoagulant surfaces (PVPyrH). Films were painted on, or spread by knife coating. 

To make nanoparticles able to escape complement activation, Passirani et alJ" proposed to coat nanospheres with heparin. This compound, which is a polysaccharide, is a physiological inhibitor of complement activation in vivo. Heparin-coated poly(methylmetha-crylate) nanoparticles were prepared by emulsion polymerization. In the method, the radical polymerization of methylmethacrylate was initiated by heparin according to an original method involving cerium ions and allowing heparin to covalently attach to poly(methyl-methacrylate). 

Anthrylpolyamines 12-15 (Figure 15) were prepared via dmple substitution reactions of 9-(chloromethyl)anthracene. The full emission spectra of 12-15 (all 1 pM) were collected during titration with ds DNA, ss DNA, heparin, and poly-L-glutamate representative titration data from the monitoring of compound 14 at 422 run are drown in Figure 16. Bodi disubstituted anthracenes (14 and 15) exhibit a 6-nm red shift in when bound either to ds DNA or to ss DNA likewise, both monosubstituted anthracenes (12 and 13) show a 14-nm red shift in their emission spectra in the presence of either ds or ss DNA. Interaction of the nucleotide bases with the anthracene is a likely source of the bathochromic shift and the observed CHEQ effect Such n-stacking with ss DNA, seldom observed with intercalating compounds, may result from the favorable entropy effect of electrostatic preassociation (18). 

The anthrylpolyamine most effective in binding to heparin (14) was used to follow the activity of heparinase at pH 5. Samples were prepared containing 1 pM probe 14 and 5 pM heparin in 0.1 M pH 5 NaOAc buffer with 0.05 mM EDTA. Under these conditions, the fluorescence of probe 3 is at its minimum as a result of template-directed excimer formation. Addition of heparinase, an enzyme that hydrolyzes heparin to oligosaccharide units (19), results in a flurescence enhancement as shown in Figure 17. One of the most effective polyglutamate binders (13) was used to test the activity of pronase at pH 5. Samples were prepared containing 1 pM probe 13 and 90 pM poly-L-glutamate in 0.1 M pH 5 NaOAc buffer with 0.05 mM EDTA. Under these conditions, the fluorescence of probe 13 is also at its minimum. Addition of pronase, a nonselective proteolytic... 

Functions.—Heparin fractionated by gel filtration appeared to bind to two sites on antithrombin III (association constants 0.6 x 10 and 0.2 x 10 moll" ), whereas heparin prepared by affinity chromatography on matrix-bound antithrombin III appeared to bind to only one site (association constant 2.3 x 10 moll ). These results suggest that one of the binding sites on antithrombin III does not bind the most active heparin components, but accommodates heparin-like molecules which, although similar in size to the active heparin components, have little or no anticoagulant activity. Heparins with high or low affinities for antithrombin III exhibited no differences in their abilities to bind lipoprotein lipase. Studies of the interaction between the lipoprotein lipase from cow s milk and Sepharose-immobilized heparin have shown that heparin is poly-disperse. Whereas heparin facilitated complex formation between a-thrombin and antithrombin III, it had little effect on the interaction between p-thrombin and antithrombin III. ... 

Interest continues in the binding of heparin to polymers in an attempt to produce non-thrombogenic surfaces. This has been the aim in the use of glutaralde-hyde-protein complexes as coatings for latex rubber and polyurethanes. Glutaraldehyde has also been used to bind antibodies to partially hydrolysed polyamide surfaces for enzyme-linked radioassay techniques. One of the few examples of direct polymerization (as opposed to surface modification) in an attempt to produce polymers having improved compatibility involves the use of 2-methacryloyloxyethylphosphoryl choline in the formation of homopolymers and copolymers with methyl methacrylate. An isocyanato-urethane methacrylate has been synthesized from 2-hydroxyethyl methacrylate in connection with dental materials research in which the preparation of poly functional monomers for improvement of interfacial bonding with tooth tissue is a topic of some interest. 

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