Blood-compatible surface

Ishihara K (1997) Novel polymeric materials for obtaining blood compatible surfaces. Trends in Polym Sci 5 401 -07... 

Keywords Biomaterials Blood compatibility Surface modification Polyurethane Hydrogen bond Endothelialization Protein adsorption... 

Blood compatible surfaces were prepared by the author [2] by UV curing of benzophenone-containing polyethylene ether, (II). 

This modification could be made by plasma polymerization wherein a thin, highly cross-linked and pin hole free film of filler free silicone polymer could be added onto a variety of substrate materials in order to prepare improved blood compatible surfaces (1). Alternatively, gaseous plasma could be used to add new chemical groups to a material surface which could then be used for attaching a variety of biomolecules. By anhydrous ammonia plasma, amino groups can be added to the surface of polypropylene membranes or to the surface of polypropylene beads. These amino groups can then be employed to bind albumin to polypropylene as was done in our previous work in which a quantitative measure of bound protein was... 

Recent Hypotheses about Blood-Compatible Surfaces.106... 

The chemical structure of smooth polymer surfaces is specified by ionogenidty, hydrophobicity, hydrophilicity, and their distribution. Polyma blood compatibility is undoubtedly dependent on the chemical structure. Therefore, a variety of hypotheses about the optimum blood-compatible surface exist. 

Recently, it has been realized that biomaterials that are surface-modified with zwitterionic compounds demonstrate excellent blood compatibility (Figure 11.6). Zwitterionic compounds have both cationic and anioific groups in the same molecules and form a betaine structure. There are three kinds of zwitterionic groups that have been investigated for use in obtaining a blood-compatible surface. Sulfobetaine compounds have a sulfonate anion and trimethyl ammonium cation in the same molecule, similar to heparin. The sulfobetaine group is introduced at the surface of PU and has been evaluated for blood compatibihty. Lin et al. reported that sulfobetaine polymers can effectively suppress platelet adhesion and protein adsorption [60-71]. Also, Lowe et al. 

Dai et al. [69] modified the surface of microporous polypropylene (PP) membranes with phospholipid polymer using a new economic and convenient method. The process included the photo-irradiated graft polymerization of N-N-dimethylaminoethyl methacrylate (DMAEMA) and the ring-opening reaction of the grafted polyDMAEMA with 2-alkyloxy-2-oxide-l,3,2-dioxophospholanes (AOP). The FTIR spectra confirmed the chemical changes of the membrane surface and supported that PP membrane with excellent blood compatible surface could be fabricated by their novel method. 

Our previous experience lead us to select HMDS as the monomer for the treatment. We have coated several nonblood-compatible materials by plasma polymerization of this monomer in a glow-discharge system to create blood-compatible surfaces for diverse biomedical applications (18-21 ). We have shown that this treatment significantly increase the blood-compatibility without affecting the substrate material properties. 

By varying the exit angle, surface concentration profiles can be investigated by means of ESCA . A recent study, of medical interest, dealt with blood-compatible surfaces. The systems studied were colloidal heparin, or dextran sulphate stabilized with hexadecyl ammonium chloride, deposited onto steel substrates, and chemically related substances. Using the angular dependence techniques it was then found that the intensity ratio for the S2p peaks from disulfide and sulphate exhibit exit angular dependences for albumin covered... 

Parallel to the development of thromboresistant and hopefully completely compatible polymers or surface treatments, research proceeded on (a) the development of methods to evaluate blood compatibility, and (b) the understanding of blood-material interactions that define compatibility. The latter would not only contribute to the development of badly needed improved evaluation methods but also form the basis for the development of truly blood-compatible surfaces. The most recent comprehensive review of blood-materials interactions is found in Reference No. 4. 

---