Blood compatibility properties

Amiji, M. M. 1995. Permeability and blood compatibility properties of chitosan-polyfethylene oxide) blend membranes for haemodialysis. Biomaterials 16 593-599. 

Anderson, D., Nguyen, T., Lai, P.N., and Amiji, M. 2001. Evolution of the permeability and blood-compatibility properties of membranes formed by physical interpenetration of chitosan with PEO/PPO/PEO triblock copolymers. J. Appl. Polym. Sci. 80 1274-1284. 

The bulk, surface, and blood compatibility properties of a series of SPUs based on PEO (molecular weight (MW)=1450), poly(tetramelhylene oxide) (PTMO) (MW = 1000), and mixed PEO/PTMO soft segments were evaluated [25,26], Two polymer blends prepared from a PTMO-based and a PEO-based SPU were also... 

All these studies highhght the possibility of using PURs as drug delivery systems with the potential of a modulated release profile obtained by properly tuning material composition. PURs, as discussed in the previous sections of this chapter, also display excellent mechanical and blood compatibility properties, suggesting their use for implanted drug release devices. 

Plasma processing technologies ate used for surface treatments and coatings for plastics, elastomers, glasses, metals, ceramics, etc. Such treatments provide better wear characteristics, thermal stability, color, controlled electrical properties, lubricity, abrasion resistance, barrier properties, adhesion promotion, wettability, blood compatibility, and controlled light transmissivity. 

Biomedical Applications Due to their excellent blood compatibility (low interaction with plasma proteins) and high oxygen and moisture permeabilities, siloxane containing copolymers and networks have been extensively evaluated and used in the construction of blood contacting devices and contact lenses 376). Depending on the actual use, the desired mechanical properties of these materials are usually achieved by careful design and selection of the organic component in the copolymers. 

After almost half a century of use in the health field, PU remains one of the most popular biomaterials for medical applications. Their segmented block copolymeric character endows them with a wide range of versatility in tailoring their physical properties, biodegradation character, and blood compatibility. The physical properties of urethanes can be varied from soft thermoplastic elastomers to hard, brittle, and highly cross-linked thermoset material. 

Chitosan is the main structural component of crab and shrimp shells. Chitosan contains both reactive amino and hydroxyl groups, which can be used to chemically alter its properties under mild reaction conditions. Al-acyl chitosans were already reported as blood-compatible materials. UV irradiation grafting technique was utilized to introduce obutyrylchitosan (OBCS) onto the grafted SR film in the presence of the photosensitive heterobifunctional cross-linking agent. The platelet adhesion test revealed that films grafted on OBCS show excellent antiplatelet adhesion. 

Hydrophobic or Hydrophilic Polymers with Excellent Mechanical Properties and Flexibility, Tunable Surface Energy for Cardiovascular Applications. Blood Compatibility ... 

The design of bioeompatible (blood compatible) potentiometric ion sensors was described in this chapter. Sensing membranes fabricated by crosslinked poly(dimethylsiloxane) (silicone rubber) and sol gel-derived materials are excellent for potentiometric ion sensors. Their sensor membrane properties are comparable to conventional plasticized-PVC membranes, and their thrombogenic properties are superior to the PVC-based membranes. Specifically, membranes modified chemically by neutral carriers and anion excluders are very promising, because the toxicity is alleviated drastically. The sensor properties are still excellent in spite of the chemical bonding of neutral carriers on membranes. 

Similarly to the phospholipid polymers, the MPC polymers show excellent biocompatibility and blood compatibility [43—48]. These properties are based on the bioinert character of the MPC polymers, i.e., inhibition of specific interaction with biomolecules [49, 50]. Recently, the MPC polymers have been applied to various medical and pharmaceutical applications [44-47, 51-55]. The crosslinked MPC polymers provide good hydrogels and they have been used in the manufacture of soft contact lenses. We have applied the MPC polymer hydrogel as a cell-encapsulation matrix due to its excellent cytocompatibility. At the same time, to prepare a spontaneously forming reversible hydrogel, we focused on the reversible covalent bonding formed between phenylboronic acid and polyol in an aqueous system. 

Significant research has been directed toward the use of polyelectrolyte complexes as blood compatible materials. Several investigators found that water-insoluble polyelectrolyte complexes can suppress blood coagulation [487-490]. Davison and coworkers reviewed and studied the biological properties of water-soluble polyelectrolyte complexes [491] between quatemized poly(vinyl imidazole) or polyvinyl pyridine) and excess sulfonated dextran or poly(methacrylic acid). By forming complexes with a stoichiometric excess of anionic charge, a more compact conformation with anionic character was obtained. 

Ikada and coworkers also studied the blood compatibility and protein denaturation properties of heparin covalently and ionically bound onto polymer surfaces [513], Both types of bound heparin gave deactivation of the coagulation process. Clotting deactivation was attributed to a heparin/ antithrombin III complex by covalently bound heparin which gave adsorbed protein denaturation and platelet deformation as compared with lack of these features with ionically bound heparin. 

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. 

Benvenuti M, Dal Maso G (1989) In Dawids S (ed) Polymers their properties and blood compatibility p 259... 

Biocompatibility (See Table 1), which is a phenomenological concept, is the essential property of biomaterials. For instance, the inner surface of an implanted vascular graft or blood pump (artificial heart) must be blood-compatible, while its outer surface must be tissue-compatible. In other words, the material surfaces must not exert any adverse elfects upon blood or tissue, or upon other biological elements at the interfaces. 

Since the 1970s, a number of reports on biomaterials other than SPU have also been presented, providing us with evidence which shows the important role played by microdomain structures in realizing excellent biomedical properties. For instance, an A-B-A type block copolymer (HEMA-St—HEMA) (See Sect. 4.2) was shown to form microdomain structure and to exhibit excellent blood compatibility in both in vitro and in vivo tests. 

Studies to elucidate the correlation between the structure of the polymer gels and their blood compatibility were carried out by means of 13C-NMR (for mobility of the PEG chains) and H-NMR and DSC (for the effect of water on their properties). Results are shown in Table 7. By comparing these results with one another, Tanzawa et al. concluded that material surfaces with the highest fraction of water molecules of intermediate mobility exhibit the best blood compatibility. This was supposed to come from a similar mobility of the intermediate water compared to that of oligosaccharides on the outermost surface of the cell... 

Though we must be careful in discussing the structure-property relationship in terms of the blood-compatibility of SPUs, PEUs - such as PTMO-PU or PEO-PU - normally exhibited worse compatibility than PEUU (e.g. Biomer). For instance, Cooper et al. [21] reported a serious thrombogenicity of PTMO-PU as well as PEO-PU when these materials were brought into... 

Blood compatibility of PEG-modified surfaces was discussed in terms of the mobility of water molecules at the interface of hydrogel materices. The property and application of poly(N-isopropylacrylamide) and its copolymers as thermoresponsive hydrogel were also reviewed. 

Most of these studies have been performed on relatively uncharacterized LTI carbon surfaces. Since we assume that a large part of blood compatibility depends on the nature of the solid-plasma interface, particularly with respect to protein adsorption, we have elected to characterize some of the surface properties of LTI carbon in hopes of further understanding the solid-blood interaction mechanisms. 

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