Adsorption of plasma proteins

An important factor in the interaction of foreign surfaces with blood is the rapid adsorption of plasma proteins onto such surfaces when they are exposed to blood (4). For this reason the adsorption of radioactively tagged blood components on heparinized and unheparinized surfaces was measured. Proteins were dissolved in approximate physiological concentrations in a buffered (pH 7.35) physiological saline solution and the solutions were exposed to the test surfaces for 2 hours at 37 °C. in a static system. After the exposure, the surfaces were rinsed with physiological saline and distilled water and then dried. The amount of protein on the surfaces was determined in a 27r-gas flow proportional counter (7). As shown in Table III, although both heparinized surfaces were nonthrombogenic, there is no consistent pattern of either increased or decreased adsorption of the proteins caused by the heparinization. In-... 

Stability in plasma is an important requirement for IV emulsions as flocculated droplets may result in lung embolism. It was found that tocol-based emulsions stabilized by sodium deoxycholate/lecithins flocculated strongly when mixed with mouse, rat, and sheep plasma and serum, whereas soya oil-based emulsions with the same emulsifiers did not [123], It was hypothesized that this effect was caused by the adsorption of plasma proteins onto the tocol droplets (opsonization). Indeed, the steric stabilization of emulsions by incorporation of emulsifiers like poloxamer 188 or PEGylated phospholipids such as PEG5000PE proved to be effective in the stabilization of tocol-based emulsions in plasma. Conversely, in vitro studies were... 

Tamilvanan, S., Schmidt, S., Muller, R. H., and Benita, S. (2005), In vitro adsorption of plasma proteins onto the surface (charges) modihed-submicron emulsions for intravenous administration, Eur. J. Pharm. Biopharm., 59,1-7. 

Figure 7. Competitive adsorption of plasma proteins onto FEP...

Relationships between Adsorption of Plasma Proteins and Adhesion of Platelets... 

Another widely adopted ISRP phase, called the BioTrap 500, was used by Needham and co-workers to inveshgate the utility of RAM media for rapid-discovery bioanalysis [58]. The exterior of this phase is coated with O 1-acid glycoprotein (AGP), which prevents adsorption of plasma proteins. An alternate-regenerate system, similar to that depicted as Figure 11.3, was employed to yield an overall duty cycle of about 2.5 min/sample. 

JL Brash, DJ Lyman. Adsorption of plasma proteins in solution to uncharge surfaces. J Biomed Mater Res 3 175, 1969. 

Adsorption of plasma proteins was studied by pumping 37°C plasma through the tubes (prefilled with degassed buffer at 37°C) for 2 h at 100 mL/min. Rinsing was done by pumping 37°C buffer through the tubes for 1 min. The tube was drained of the buffer, filled with SDS sample buffer, immersed in an ultrasonic bath kept at 50°C, and sonicated for 1 h. The eluate from each tube was then concentrated approximately tenfold and frozen at — 70°C until electrophoresis was done. 

The adsorption of plasma proteins to polymers precedes the interaction of blood cells with the surfaces, and therefore, is likely to be an important initial event in the response of blood to polymers (25, 29). At present, however, little is known about the adsorbed protein layer, even though it has been studied in some detail in recent years (30-36). Because protein adsorption from blood plasma is a competitive process, differences in the adsorbed layer on different polymer substrates could be a primary cause of differences in thrombogenicity. Previous studies of the composition of the adsorbed protein layer have employed 12oI-labeled protein added to plasma (37-39), antibody binding (34) to detect individual proteins, or electrophoretic analysis of detergent-elutable proteins (17, 33, 35). The procedure used in this study does not require the large surface areas used in previous work (35), nor does it rely on incorporation of radiolabels (36) into adsorbed protein. Instead, a staining method at least 100-fold more sensitive than these other techniques has been used. 

Effect of Electrical Signals on the Adsorption of Plasma Proteins to a High Copper Alloy... 

We chose to study the adsorption of plasma proteins to surfaces by using high resolution transmission electron microscopy. This allowed us to assess conformational changes of the protein molecules due to the specific surface to which they are adsorbed, and to examine surfaces following initial protein adsorption. Utilizing this technique, we have been able to observe individual molecules as well as the structure of the protein films adsorbed to these surfaces. 

Static Adsorption of Plasma Proteins on Glass. Initial studies of the interaction of proteins with artificial surfaces concerned the highly simplified situation of static adsorption on glass from solutions of purified radiolabeled human plasma proteins. Albumin was chosen as a major plasma protein known for its non thrombogenic properties (5>6). Fibrinogen and fibronectin, on the contrary, are major proteins of plasma which enhance platelet and cellular adhesion (4.5.7.23-25). 

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