Heparin-polymer

The TDMAC-based procedures make it possible to modify most of the commercially available polymers, heparin being much more strongly attached to the polymer than in the case when the graphite-benzalkonium chloride procedure is applied (Table 2). 

Polymers heparinized via the procedures involving anion-exchange Amberlite XE-255 resin > 480... 

A perspective method for the production of HCP was proposed by Labarre et al 92-94) [t invo]ves radical graft-copolymerization of methyl methacrylate onto heparin effected by cerium salts (Ce4+). As well as other hydroxyl-containing polymers, heparin may react with cerium ions producing free radicals which may initiate graft-copolymerization of unsaturated compounds ... 

Heparinization Heparin released polymer Heparin immobilized polymer ... 

Y. Ito, M. Sisido and Y. Imanishi, Synthesis and antithrorabogenicity of polyetherurethane urea containing quaternary ammonium groups in the side chains and of the polymer/ heparin complex./. Biomed.Mater. Res. 20 1017-1033,1986. 

The objective of this work has been the synthesis of a new polymer-heparin conjugate and complementary polymer-heparin binding peptide conjugate for the formation of hydrogels. This investigation is motivated by the opportunities to utilize these and other related polymeric architectures as platforms for producing... 

Second, bromination of methyl groups attached to arylphenoxy-phosphazene polymers converted them to CH2Br units (22). These were then quaternized with triethylamine, and the quaternary sites were used for anion exchange with sodium heparin (Fig. 2). The... 

Figure 48-9. Structure of heparin. The polymer section illustrates structural features typical of heparin however, the sequence of variously substituted repeating disaccharide units has been arbitrarily selected. In addition, non-O-sulfated or 3-0-sulfated glucosamine residues may also occur. (Modified, redrawn, and reproduced, with permission, from Lindahl U et al Structure and biosynthesis of heparin-like polysaccharides. Fed Proc 1977 36 19.)...

Polymeric carbohydrates are usually encountered as distributions, so high resolution is rarely important. Of all biological macromolecules, carbohydrates are particularly amenable to analysis by GPC because hydrophobic interactions are typically weak. A section below is devoted to the analyses of carboxymethylcellulose and xanthan. Other examples of polysaccharides of interest are hyaluronic acid,62 polymers of (l-glucose,121125 heparin,126127 cellulose and chitin,128 and Mucorales extracellular polysaccharides.129... 

It is important to note that the foregoing, biosynthetic-polymer modification is usually incomplete. In fact, only a fraction of the heparin precursor undergoes all of the transformations shown in Scheme 1. However, as the product of each enzymic reaction constitutes the specific substrate for the succeeding enzyme, the biosynthesis of heparin is not a random process. Thus, sulfation occurs preferentially in those regions of the chain where the amino sugar residues have been N-deacetylated and N-sulfated, and where D-glucuronic has been epimerized to L-iduronic acid.20... 

Free hydroxyl groups of heparin have been caused to react with methyl iodide, to afford methoxyl derivatives,100,101,264 with chlorosul-fonic acid-pyridine266 or chlorosulfonic-sulfuric acid,267 to give su-persulfated heparins, and with methacryl chloride, to provide a water-soluble, heparin methacrylate268 that can be condensed to heparin polymers. 

To investigate heparin release in response to an electric current, the swollen heparin-polymer matrix was attached to a woven platinum cathode in a continuously stirred PBS solution (pH 7.4), and an electric current of 20 mA was applied. When the electric current was on, the polymer surface facing the cathode dissolved, thereby releasing heparin. The amount of heparin released was assayed by the Azure II method at pH 11 to prevent complexation of the two dissolved polymers. The release pattern of heparin showed a complete on-off profile in response to the applied electric field, as shown in Figure 23 [50],... 

A Gutowska, YH Bae, H Jacobs, J Feijen, SW Kim. Heparin release from thermosensitive polymer coatings In vivo studies. J Biomed Mater Research 29 811-815, 1995. 

In practice, some anticoagulation agents such as heparin or antiplatelet agents, e.g. nitric oxide (NO) are delivered to sensor sites in order to reduce the risk of thrombus formation. Nitric oxide (NO), which is a potent inhibitor of platelet adhesion and activation as well as a promoter of wound healing in tissue, has been incorporated in various polymer metrics including PVC (poly(vinyl-chloride)), PDMS (poly-dimethyl-siloxane) and PU (poly-urethanes). Those NO release polymers have been tested in animals as outer protection coatings and have shown promising effects for the analytical response characteristics of the sensor devices [137],... 

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