Protein-based surfactants general

These phenomena obviously provide means of separating proteins based on the addition of appropriate surfactants, at the appropriate pH, with control of electrolyte concentration, and so on, and will not be elaborated upon here (see, however. Chapter 4, Section II.D and III.E). Subsequent to the above work by protein chemists it was found that similar precipitation reactions occur between cationic surfactants and a variety of anionic polyelectrolytes, those investigated being generally anionic polysaccharides (114-116). Scott (115), for example, found for anionic polysaccharides with weak acidic groups (hyaluronic acid, alginic acid, etc.) that precipitation with CTAB could be inhibited as a result of deionization of their carboxyl groups. With carbohydrate monoester sulfates, such as dex-tran sulfate, no such inhibition was observed. He also reported that the flocculation endpoint observed for this polyelectrolyte with CTAB corresponds to the formation of a stoichiometric salt. 

More recent publications on sulfosuccinates have confirmed the minimal or close to zero skin and eye irritation caused by these products. In a general screening of product safety evaluation methods the authors [16] rejected the sulfosuccinate from further consideration in the statistical analysis of experimental data (variance analysis) because the product had not shown any irritation in the Duhring-Chamber test. The sulfosuccinate (based on fatty alcohol ethoxy late) was tested in a screening with 14 other surfactants, namely, alkyl sulfates, sulfonates, ether sulfates, and a protein fatty acid condensation product. 

It is pertinent to note here the observed increase in the value of the structure-sensitive parameter p from 1 to 2. This implies that the architecture of the sodium caseinate aggregates, as modified by interaction with the surfactant, becomes generally more open, despite the inferred collapse of their constituent protein nanoparticles. In contrast, a shell-like aggregation structure can be inferred for the self-assembly of sodium caseinate as a result of its interaction with the non-ionic surfactant PGE (this surfactant is based on a mixture of the esters of stearic and palmitic acids in chemical combination with polyglycerol (Krog, 1997)). 

Surface properties of proteins in general, 296-298 (table) purification methods based on, 272 Surface tension and interfacial properties, 609-628. see also Interfaces Surfactants, see also Interfacial tension definition and adsorption kinetics of, 617-618, 639... 

Emulsions are dispersions of one fluid into another. Both oil-in-water and water-in-oil emulsions are encountered. Foams are similar to emulsions, but the dispersed phase is a gas. Emulsions are everywhere some examples of products that are based on emulsions are salad dressings, mayonnaise, egg yolk, milk, margarine, cream, ice cream, waterborne paints and bitumen. Emulsions are generally not stable, so they need to be stabilized against coalescence. One can use surfactants for that, or polymers, such as proteins and polysaccharides, or particles. 

The protein-clay interaction is generally based on the negative charges of the enzymes, when deposited at pH values higher than the relevant isoelectric point. The enzyme can electrostatically interact with the positive charges at brucite-like layers in LDHs [103, 118] or with the surfactants added to positive clays to form organoclays [13, 119]. 

An interesting application of aqueous IL microemulsions is to develop IL polymer materials incorporating enzymes that can be used as active, stable, and reusable biocatalysts [65].The IL l-vinyl-3-ethylimidazolium bis(trifluoromethylsulfonyl) amide ([veim][Tf2N] see Scheme 13.2) was used as the continuous phase. Incorporation of proteins in IL-based polymer frameworks is generally difficult because they are insoluble in most ILs.To overcome this limitation, the authors first employed water/Tween-20/[veim][TfjN] microemulsions to solubilize the enzyme in an IL phase and then incorporated the enzyme within these surfactant aggregates into IL polymer frameworks via polymerization in the presence of an IL-soluble cross linker and initiator. 

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