Polymer heparin-like

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.)...

Problems of desorption and loss of activity encountered with natural heparin have led numerous workers to explore synthetic heparin-like polymers or heparinoids, as reviewed by Gebelein and Murphy [475, 514, 515]. The blood compatibility of 5% blended polyelectrolyte/polyfvinly alcohol) membranes was studied by Aleyamma and Sharma [516,517]. The membranes were modified with synthetic heparinoid polyelectrolytes, and surface properties (platelet adhesion, water contact angle, protein adsorption) and bulk properties such as permeability and mechanical characteristics were evaluated. The blended membrane had a lower tendency to adhere platelets than standard cellulose membranes and were useful as dialysis grade materials. 

R. Ojeda, J. L. de Paz, and M. Martin-Lomas, Synthesis of heparin-like oligosaccharides on a soluble polymer support, Chem. Commun., (2003) 2486—2487. 

These anticoagulant polymers may be divided into two major categories, namely "AT Ill-like" or "heparin-like" materials, according to their different interaction mechanisms with thrombin... 

HEPARIN-LIKE SUBSTANCES AND BLOOD-COMPATIBLE POLYMERS OBTAINED FROM CHITIN AND CHITOSAN... 

Wettability, surface free energy, surface charge and compliance have been studied. Heparinized surfaces have exhibited considerable compatibility with blood. Typically, heparin is surface bound using cationic materials including tridodecyl methylammonium chloride, benzalkonium chloride, octadecylamine and quaternary ammonium polymers. Since polyelectrolyte complexes of heparin and chitosan have been prepared and exhibit either thrombogenic or non thrombogenic properties chitosan can be coated onto artificial polymeric supports and then reacted with heparin or with heparin-like substances... 

Wang LR, Qin H, Nie SQ, Sun SD, Ran F, Zhao CS. Direct synthesis of heparin-like poly(ether sulfone) polymer and its blood compatibihty. Acta Biomater 2013 9 8851-63. 

Other new catalysts under development include the heparosan synthase enzyme, pmHS, and its derivatives. Heparin-like polymers will interact with other proteins in the vertebrate body including coagulation factors and growth factor receptors. We expect that pmHS will possess certain catalytic properties exhibited by pmHAS and pmCS. 

Polymers that are structurally related to heparin and that possess certain of its biological properties, such as anticoagulant activity, are commonly called heparinoids. Non-heparin glycosaminoglycans having anti-coagulant/antithrombotic activities are sometimes classified as heparinoids. Heparinoids are also prepared by modification of naturally occurring polysaccharides, by the total synthesis of heparin-like polymers, and most recently by the synthesis of small sulfated heparin-like oligomers. 

Synthetic polymers such as poly(vinyl sulfate) and poly (anethole sulfonate) are highly charged heparin-like polyanions that also exhibit anticoagulant activity.23 However, these agents are not used in vivo as they are resistant to metabolism and thus remain in the body for extended periods resulting in toxic side effects. 23... 

Section II is devoted exclusively to polysaccharide systems, but includes a fairly broad variety of polymers and applications. Kennedy et al. describe some industrially important polysaccharides, while Morris covers various bacterial-derived polysaccharides used in the food and agricultural industries. Carraher et al. describe some tin modified dextrans in the third Chapter of this Section. Some acidic, heparin-like, polysaccharides are described in the following Chapter (Linhardt, et al.) then Kobayashi reveals some cellulose derivatives which form liposomes and membranes. The final three papers of this Section deal with chitin and chitosan systems. Alkaline chitosan gels are presented by Hirano et al. Kikuchi and Kubota then describe some polyelectrolytes derived from chitosan derivatives. Finally, Seo and lijima consider the sorption behavior of chitosan gels. 

---