Blood Interactions

Fig. 24. Matsuda, et al. s model of the protein adsorption/denaturation/aggregation/desorption/ delamination process involved in the blood interactions of materials (from Ref. 127 , p. 357)...

Horbett, T. A., Frinciples underlying the role of adsorbed plasma proteins in blood interactions with foreign materials. Cardiovasc. Pathol. 2,137S-148S (1993). 

Brain and blood interactions occur at three interfaces endothelial cells, which form the major site of the BBB, the choroid plexus ependymal cell lining, and the arachnoid granulations. These sites are key in regulating the exchange of substances between brain and blood, thus maintaining the composition of brain electrolytes, as well as the content of proteins and other substances. 

LTI pyrolytic carbon is one of the very few synthetic materials generally accepted as suitable for long-term blood contact applications (1 ). Although a number of hypotheses have been formulated with respect to the blood tolerability of materials, a general theory or mechanism is not yet available. Nyilas, et al., ( ) have shown that in certain situations the local hemodynamics can play a predominant role, while in most cases the solid-blood interfacial properties have been shown to be equally important (2, 3). It is assumed that understanding the plasma protein adsorption processes on solids used for blood-contact applications will lead to a better understanding of solid-blood interactions (, 2, ... 

Kim, et al., ( ) have utilized radioiodinated (I proteins to measure adsorption of individual proteins and protein mixtures on LTI carbon surfaces. Their results indicate a very rapid adsorption of albumin onto the LTI carbon surface, consistent with Kim s model of blood interactions via a platelet-adhesion mechanism (.8). Microcalorimetric and electrophoretic mobility studies of protein adsorption on LTI carbon surfaces have been done by Chiu, et al., ( 5). The extension of the adsorbed protein layers have been directly measured by Fenstermaker, et al., ( ) and Stromberg et al., 7) at NBS using ellipsometric methods. 

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. 

Magos L. 1967. Mercury-blood interaction and mercury uptake by the brain after vapor exposure. Environ Res 1 323-337. 

Blood interacts with dry reagents on test strip. 

Table I. Factors Influencing Blood Interactions at Foreign Interfaces...

ESCA is the only technique that (to date) allows a direct correlation to be made between surface chemistry and in vivo blood interaction (21-23). 

Surface characterization is very important in the development of blood-compatible biomaterials, since the surface characteristics of the polymer have been linked to polymer-tissue and polymer-blood interactions. Further information on surface characterization of biomaterials can be found elsewhere (20, 21). 

Blood compatible materials are essential for artificial organs which are used in contact with blood. The immunological aspects of blood compatibility are stressed. Complement activation induced by material-blood interaction is most likely related to transient leukopenia during extracorporeal circulation such as hemodialysis. Although transient, it may be harmful, especially if it occurs frequently. Some complications associated with hemodialysis may be caused due to the repeated complement activation and leukostasis in the lung. Cellulosic membranes induce the phenomenon more severely than synthetic membranes. Reused cellulosic membranes sterilized with aldehyde after the first use show less complement activation and leukopenia. Aldehyde treated biological substances may play a important role in enhancing blood compatibility. 

Graham. Blood interactions with novel polyurethaneurea hydrogels. 

In conclusion, it may be summarized that the annealing of PVA film in the presence of plenty of glycerol makes it possible to produce a diffuse layer on the PVA surface without any chemical modification. In addition, the resulting PVA hydrogels have low water contents such as 30 %. Finally, it should be stressed that blood interactions of PVA are greatly influenced by the history of the PVA sample preparation. 

Table 6.1. Variables influencing blood interactions with cardiovascular devices...

Fink, H., 2009. Artificial Blood Vessels Studies on Endothelial Cell and Blood Interactions with Bacterial Cellulose (Doctoral thesis). University of Gothenburg. Sahlgrenska Academy, Institute of Clincial Sciences. Department of Surgery. 

The objective of this article is not to give a detailed review of the theories but to unify the above diverse hypotheses as much as possible. For this purpose, we will refer mostly to the results observed in our laboratories. General aspects of blood interaction with polymer surfaces are described in other publications... 

A number of polymer surface parameters, e.g. surface free energy and surface charge, are responsible for blood interaction phenomena. Regarding the correlation of hydrophilidty and thrombocyte adhesion, Ikada et al. determined a maximum of thrombocyte adhesion for a contact angle region between 60 and 80° [95]. Van Wachem et al. showed that the best blood compatibility of polymer blends is achieved for moderate wettability [96]. The influence of polar and dispersive components of the surface tension on blood compatibility was described by Kaelble and Coleman [97,98]. They found that polymers with high dispersive (y ) and low polar components (yP) of surface tension show better blood compatibility than polymers with low dispersive interactions. Furthermore, a nega-... 

Fig. 10. Blood compatibility parameter X/X as a function of Ys / /s after the blood interaction with the water-extruded PPE/EVA blend (Xq value without surface interaction)...

Major challenges to using diamond-like carbon for impiantabie medicai devices ceiiuiar and blood interactions... 

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