Biomaterials, hemocompatibility

The interaction in an interface of device/tissue is limited by two factors. There is the corrosive environment, such as biological fluid, which contains salts and proteins among other cellular structures in which the sensor device must survive [47, 48], Second, there is the encapsulation material which may induce a toxic reaction due to poor biocompatibility and hemocompatibility [49, 50], It is crucial to use a biomaterial that can overcome both limiting factors to maintain the lifetime of the sensor device and protect the body [51, 52],... 

The in vitro study of the hemocompatibility of biomaterials requires the consideration of many parameters, static or dynamic contact, flow rate, wall shear rate, form of biomaterial to be tested, pathway to consider (platelet adhesion, platelet activation, complement activation, contact phase activation etc..) and duration of contact(39). It has previously been demonstrated t t hemodynamic circumstances play a significant role in determining localization, growth and fiagmentation of thrombi and platelet adhesion in vivo, and that flow rate controls platelet transport to a surface and their adhesion (40). This evidence is siqtpoited by observed differences in platelet activity predominance in venous and arterial flow (41). Qearly, defining the blood compatibility of a material is a conqrromise between a number of these factors. 

Annual Book of ASTM Standards (2001) Section 13, Medical Devices and Services. West Conshohocken, PA ASTM. Janvier GC, Baquey C, Roth N, et al. (1996) Extracorporeal circulation, hemocompatibility and biomaterials. Annals of Thoracic Surgery 62 1926-1934. 

Weber N, Wendel H P, Ziemer G (2002). Hemocompatibility of heparin-coated surfaces and the role of selective plasma protein adsorption. Biomaterials. 23 429-439. 

L.P. Amamath, A. Srinivas, A. Ramamurthi, In vitro hemocompat-ibility testing of UV-modified hyaluronan hydrogels. Biomaterials 27 (8) (2006) 1416-1424. 

Several issues are important in the selection of tests for hemocompatibility of medical devices or biomaterials. In vivo testing in animals may be convenient however, species differences in blood reactivity must be considered and these may limit the predictability of any given test in the human clinical situation. While species differences may complicate hemocompatibility evaluation, the utilization of animals in short- and long-term testing is considered to be appropriate for evaluating thrombosis and tissue interaction. European community law prohibits the use of nonhuman primates for blood compatibility and medical device testing, even though blood values and reactivity between humans and nonhuman primates are very similar. Hemocompatibility evaluation in animals is... 

In cardiovascular devices, it is essential to impart hemocompatibility to PVA-C. The concept of a biomaterial-tissue hybrid in the form of endothelized PVA-C has been demonstrated. Much work still needs to be done to firmly established this approach and translate the results into the geometry of a vascular conduit. 

While the term bio compatibility refers to the tolerance of biomaterials with liquid or solid body elements, the term hemocompatibility defines the tolerance of biomaterials with bio o d. Due to the enormous demand for implants and medical-technical goods for the cardiovascular area, blood tolerance is of great importance. The discussion of blood tolerance, however, demands a separate consideration of the processes between the medium blood and the biomaterial. 

Gappa-Fahlenkamp, H., Lewis, R.S., 2005. Improved hemocompatibility of poly(ethylene terephthalate) modified with various thiol-containing groups. Biomaterials 26, 3479-3485. 

Hayward JA, Chapman D. Biomembrane surfaces as models for polymer design — the potential for hemocompatibility. Biomaterials 1984 5(3) 135—42. 

Biomaterials intended for biomedical applications should have good biocompatibility and appropriate physical properties. PUs in general have been demonstrated to have good biocompatibility and hemocompatibility [69]. In addition, since PU is easily processed and the mechanical properties can be easily tuned by modifications in chemical structure, it has been widely used in tubings, dressings, bloodcontacting devices, etc. [28,32]. 

A. Mishra, S.K. Singh, D. Dash, V.K. Aswal, B. Maiti, M. Misra, P. Maili, Self-assembled aliphatic chain extended polyurethane nanobiohybrids emerging hemocompatible biomaterials for sustained drug dehvery, Acta Biomater. 10 (2014) 2133-2146. 

These contradictory approaches and results give a first hint that research is still far from having fonnd the one and only surface modification technique for improving PU surfaces and establishing a perfectly hemocompatible biomaterial. A summary of modification techniques aiming at bioinert PU surfaces is shown in Table 10.1. 

The general aim of physical surface modification is to improve the hemocompatibility of PU biomaterials by establishing a structured surface and at the same time leave the bulk properties untouched. This ensures that the initial hemocompatibility is not changed or negatively influenced [10,97], The idea of improving the hemocompatibility... 

Major TC, Brisbois EJ, Jones AM, Zanetti ME, Annich GM, Bartlett RH, et al. The effect of a polyurethane coating incorporating both a thromhin inhibitor and nitric oxide on hemocompatibility in extracorporeal circulation. Biomaterials 2014 35(26) 7271-85. 

Chuang TW, Masters KS. Regulation of polyurethane hemocompatibility and endo-thelialization by tethered hyaluronic acid oligosaccharides. Biomaterials October 2009 30(29) 5341-51. 

Major, T.C., Brant, D.O., Burney, C.P., Amoako, K.A., Annich, G.M., Meyerhoff, M.E., Handa, H., Bartlett, R.H., 2011. The hemocompatibility of a nitric oxide generating polymer that catalyzes S-nitrosothiol decomposition in an extracorporeal circulation model. Biomaterials 32, 5957-5969. 

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