Heparin regioselective modified

INFLUENCE OF PLASMA PROTEIN AND PLATELET ADHESION ON COVALENTLY COATED BIOMATERIALS WITH MAJOR SEQUENCES OF TWENTY REGIOSELECTIVE MODIFIED N- OR O-DESULPHATED HEPARIN/ HEPARAN DERIVATIVES... 

Platelet adhesion tests on the modified cellulose membranes were done in the modified Baumgartner chamber under shear rates of 1050 sec" with citrated whole blood as described earlier Platelet adhesion tests with silicon tubes were done with citrated whole blood without any contact to unmodified surface. Luminal modified silicone tubes with regioselective modified heparin derivatives were prepared as earlier described The platelet adhesion has been measured before and after the test via percentage loss of platelets. ... 

Surface Concentration of Immobilised Regioselective Modified Heparin Derivatives... 

The regioselective modified heparin derivatives and heparin were immobilised on cellulose according to following scheme. 

There was no significant influence observed with fibronectin and IgG adsorption on regioselective modified heparin derivatives at dynamic conditions (figure not shown). In contrast to this albumin showed a... 

Influence of Individual Groups of Regioselective Modified Heparin in the Initial Phase of Album in Adhesion... 

The authors acknowledge major financial support from Deutsche Forschungsgemeinschaft DFG (project Ba 630/8-1 and Ba 630/8-2) and some additional financial support by the Gesellschaft der Freunde der Aachener Hochschule. The authors are indepted to Miss Nicole Schaath for skillful measurements, Dr. Philip de Groot for helpful discussions and the instructions for fibronectin preparation and Dr. Bemd Huppertz for helpful instructions for synthesis of regioselective modified heparin derivatives. 

Also a new end point attachment of nondegraded glycosaminoglycan type 2 (HE) or regioselective modified heparin derivatives will be described the reducing end is oxidised by electrolysis and the aldonic acid lactone formed reacts with amino groups of the polymer surface. Also coatings by ionic immobilisation (HE, ES-HS) will be described. 

Figure. I. 6 measure made immobilisation concepts for the attachment of GAG typ 2 (HE ES-HS) and regioselective modified heparin derivatives on polymer surfaces to get different coating thickness (in nm). ...

Immobilisation of GAG Type 2 (HE, ES-HS) and Regioselective Modified Heparin Derivatives... 

Carboxylated polymers were activated with a water soluble carbodiimide (CME-CDl) and reacted with GAG type 2 (HE, ES-HS) and regioselective modified heparin as described previously . ... 

The results of surface coating 10 different polymers with HE res. ES-HS can be seen in Table 1. GAG type 2 and regioselective modified heparin derivative immobilisation was achieved by amide bond formation between carboxyl groups on the polymer surface and amino groups in the GAG chain or vice versa carboxyl groups were activated by the water soluble carbodiimide N-cyclohexyl-N -(2-morpholinoethyl)carbodiimide-methyl-p-toluene sulphonate (CME-CDl). 

Ionic immobilisation of heparin is a relative simple and rapid method for the preparation of short duration antithrombotic surfaces. Maximum anticoagulant activity of the immobilised molecules is obtained because of high flexibility of the chains. Because of relatively weak surface bonding, ionic immobilised HE, ES-HS and regioselective modified HE derivatives are not intended for long time applications. 

Regioselective modified heparin derivatives may also be used in a similar manner for different nanocoatings (Fig.6). 

These regioselective modified heparin derivatives may represent sequences of ES-HS and thus will not only be used for stmcture - function studies but also in the future as a semisynthetic ES-HS. 

Figure 6. Regioselective modification of heparin. 2-O-desulphation, 6-O-desulphation, N desulphation, N+O-desulphation and 3-O-sulphation were carried out solely or combination to obtain a wide spectrum of regioselective modified heparin derivatives . ...

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