Surfactant prevent protein adsorption

MicroChannel electrophoretic devices are being developed to meet the need for better methods for protein separation and analysis. Interactions between analytes and the wall of the separation channel can reduce the efficiency of microchannel electrophoretic separations. These analyte-wall interactions are especially problematic for protein separations. Consequently, a large volume of the literature is focused on preventing protein adsorption on the walls of the microchannel by varying the microchannel material [238], by employing surfactants [239], or by modifying the microchannel surfaces [240]. 

To stabilize proteins against these degradative steps, excipients have proven to be quite effective. For instance, surfactants such as polysorbates, polyvinyl alcohol and (hpamitoyl phosphatidyl choline have been used to prevent the adsorption of proteins at the air-hquid interface during spray drying [8, 9],... 

As shown above, the improvement upon addition of surfactant of hydrolysis of Avicel was much lower than that of pretreated CWR. This result agreed well with findings by Eriksson et al. [7] who reported that surfactants and BSA were both viewed as preventing nonproductive adsorption of cellulase on lignin. However, the contrary findings reported that the non-ionic surfactants could enhance the hydrolysis of cellulose such as Sigmacell 100 and Avicel and act differently from proteins [22, 25, 38]. Therefore, more research needs to be done to solve this discrepancy and better imderstand the mechanisms of additive effect. 

Interest in the nature of interactions between shortchain organic surfactants and large molecular weight macromolecules and ions with hydroxyapatite extends to several fields. In the area of carles prevention and control, surfactant adsorption plays an important role in the Initial states of plaque formation (1-5) and in the adhesion of tooth restorative materials ( ). Interaction of hydroxyapatite with polypeptides in human urine is important in human biology as hydroxyapatite has been found as a major or minor component in a majority of kidney stones ( 7). Hydroxyapatite is used in column chromatography as a material for separating proteins (8-9). The flotation separation of apatite from... 

It has recently been shown that the inverted setup is better suited to measurement of the adsorption kinetics of protein samples at, e.g., the oil/water interface since it prevents reservoir depletion. Reservoir depletion can occur if the concentration of surfactant in the solvent phase is low. If the protein is present in the drop-forming phase, then the concentration within the drop itself may decrease during the adsorption process. This in turn would affect the measured rate of adsorption. In this case, it is preferable to form an inverted oil droplet in the protein solvent. 

Proteins are not very suitable for making fine emulsions in other words, it takes more energy to obtain small droplets than with a small-molecule surfactant. This is primarily due to their large molar mass. It causes the effective y value that they can produce at the O-W interface to be fairly large. Moreover, their molar concentration is small at a given mass concentration, causing the Gibbs elasticity to be relatively small. This means that prevention of recoalescence is less efficient. Proteins are not suitable to make W O emulsions, as follows from Bancroft s rule they are insoluble in oil. The adsorption layer of proteins on the droplets obtained by emulsification is not an equilibrium layer, whereas it is for small-molecule surfactants. 

Stabilization of emulsions by powders can be viewed as a simple example of structural- mechanical barrier, which is a strong factor of stabilization of colloid dispersions (see Chapter VIII, 5). The stabilization of relatively large droplets by microemulsions, which can be formed upon the transfer of surfactant molecules through the interface with low a (Fig. VII-10), is a phenomenon of similar nature. The surfactant adsorption layers, especially those of surface active polymers, are also capable of generating strong structural mechanical barrier at interfaces in emulsions. Many natural polymers, such as gelatin, proteins, saccharides and their derivatives, are all effective emulsifiers for direct emulsions. It was shown by Izmailova et al [49-52]. that the gel-alike structured layer that is formed by these substances at the surface of droplets may completely prevent coalescence of emulsion drops. 

Furthermore, the attachment of the hydrophobic tails will affect the surface activity more than by simply increasing hydrophobicity. As presented in Fig. 2, the attachment of hydrophobic tails will cause several domains of the protein to behave as a classical surfactant, and the overall effect will be the formation of a polymer-like surfactant. Such a polymer, which will be adsorbed at various hydrophobic interfaces, should have an increased surface activity due to the existence of many adsorption sites per molecule. This adsorption mechanism may affect the reversibility of the adsorption process and might even prevent surface denaturation. This latter effect is important in appli-... 

Chemical modification of microchip surfaces with SAMs has been used to prevent or minimize the deposition of proteins on channels. SAMs are ordered molecular assemblies that are formed spontaneously by the adsorption of a surfactant with a specific affinity of its headgroup to a substrate. Immersing an oxidized silicon wafer in a solution of an organosilicon derivative forms the SAM. The formation of a compact monolayer results in a drastic reduction of the surface wettability. 

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