Poly heparin grafted

PCL-heparin graft for electrospinning and posttreatment with VEGF Poly(trimethylene carbonate-co-L-lactide) (PTMCLAA)... 

In the works of Ferruti et al.83,84), there has been reported a method for heparinization of plasticized polyvinyl chloride which was pre-modified by grafting of poly-aminoamines. The surface concentration of ionically bound heparin was 1.2 ng/cm2. Heparin can be eluted off the polymer in a narrow pH range of 10.8 to 11.4. 

Heparin, a natural protein, is an important constituent of blood and contributes to blood clotting. When circulatory assist devices were first proposed, it was found that the artificial surfaces promoted unnatural thrombosis. An important proposed solution to the problem involved grafting heparin to the surfaces of the materials involved, including such polymers as poly(vinyl chloride) and poly(dimethyl siloxane) (Artificial Heart Program, 1968 Lyman, 1966 Sears, 1965). 

Lora et al, did try to enhance the biocompatibility of poly[bis(trifluoroethoxy)-phosphazenes] (PTFP) and poly[bis(phenoxy)phosphazenes] (PPP) by grafting different side groups on the polymer surface (Figpme 28). Graft copolymerization w ith dimethylaminoethylmethacrylate (DMAEM) onto the polyphosphazene surfaces highly enhances their biocompatibility. Subsequent heparinization has a negative effect, which is more appreciable with the PPP-based samples (Lora et al., 1991). Surface modification of poly[bis(trifluoroethoxy)phosphazene] with... 

Han DK, Lee NY, Paik KD, Kim YH, Ik Cho H, Min BG. Heparin-like anticoagulant activity of sulphonated poly(ethylene oxide) and sulphonated poly(ethylene oxide)-grafted polyurethane. Biomaterials 1995 16 467-71. http //dx.doi.org/10.1016/0142-9612(95)98819-Z. 

Salacinski HJ, Hamilton G, Seifalian AM. Surface functionalization and grafting of heparin and/or RGD by an aqueous-based process to a poly(carbonate-urea)urethane cardiovascular graft for cellular engineering applications. J Biomed Mater Res 2003 66A(3) 688-97. 

Surface block-graft-copolymerization, based on the photochemistry of N, AT-diethyldithiocarbamate has been applied to precisely design biocompatible and functional surfaces (patterns of immobilized heparin or proteins), as well as block-grafted surfaces on polystyrene [83]. Polystyrene surfaces have also been patterned by immobilization of poly(Af-isopropylacrylamide) by photolithography, and subsequently used for regiospecific cell attachment [84]. Surface modification of polydimethylsiloxane microfluidic devices by UV induced polymer grafting improved the stability of the electroosmotic mobility and improved electrophoretic resolution of peptides [85]. 

A further development of the above research, which is still in progress, is to graft poly(amido-amines) on the surface of several materials. In fact, the heparin-adsorbing ability is a surface property. It follows that grafting poly(amido-amine) chains on a given surface would impart to it the same properties found in the above graft copolymers. 

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