Stability testing, 694 surfactant association

Physical properties of the protein structure should be considered in designing strategies to achieve stable formulations because they can often yield clues about which solution environment would be appropriate for stabilization. For example, the insulin molecule is known to self-associate via a nonspecific hydrophobic mechanism66 Stabilizers tested include phenol derivatives, nonionic and ionic surfactants, polypropylene glycol, glycerol, and carbohydrates. The choice of using stabilizers that are amphiphilic in nature to minimize interactions where protein hydrophobic surfaces instigate the instability is founded upon the hydro-phobic effect.19 It has already been mentioned that hydrophobic surfaces prefer... 

Dehydration, followed by addition of the organic phase, allows micelles to flip out into a reverse micelle configuration while maintaining the hydrophobic domain of the membrane protein in a membrane-mimetic environment. In this complex, each membrane protein is thought to be associated with two reverse micelles that converge around the hydrophobic domain of the protein (Fig. 3) [225, 227, 229]. In some cases co-surfactants (e.g., dihexadecyldimethylammonium bromide (DHAB)) and/or cosolvents (e.g., hexanol) are also required to stabilize this structure. This approach was shown to be successful using the tetrameric KcsA channel as a test system [228]. Reconstitution in reverse micelles was achieved by purification in CTAB, followed by lyophilization and addition of DHAB, hexanol, pentane, and water. The result was a well-resolved HSQC spectrum for KscA, with significantly enhanced trans-... 

As a solution-based materials synthesis technique, the microemulsion-mediated method [10-18] offers the unique ability to effect particle synthesis and particle stabilization in one step. The solubilized water droplets serve as nanosize test tubes, thus limiting particle growth, while the associated surfactant films adsorb on the growing particles, thereby minimizing particle aggregation. The purpose of this chapter is to review the literature on the microemulsion-mediated synthesis of metal hydroxides and oxides the definition of a metal is extended here to include the semimetal silicon. Since metal oxides are frequently produced by decomposing metal salts, aspects of the literature on microemulsion-derived metal salts are also considered. In principle, any previously established aqueous precipitation chemistry can be adapted to the microemulsion synthesis technique. Accordingly,... 

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