97526-58-4Relevant academic research and scientific papers
Sodium ion internalized within phospholipid membranes
Menger, Fredric M.,Galloway, Ashley L.,Chlebowski, Mary E.,Wu, Shaoxing
, p. 14034 - 14035 (2006)
Seven phospholipids, modified with ester groups in their hydrophobic chains, were synthesized and examined for their ability to promote sodium ion flux across vesicular membranes. It was found by 23Na NMR that only the phospholipids having short chain segments beyond their terminal ester groups catalyze sodium ion transfer by up to 2 orders of magnitude relative to a conventional phospholipid, POPC. The rates increase with the concentration of the ester-phospholipid admixed with POPC in the bilayer. More surprisingly, the rates increase with the time allowed for the vesicles to age. This was attributed to ester-phospholipid migrating in the bilayers to form domains that solubilize the sodium ion within the hydrocarbon interior of the membrane. Such membrane domains explain why shift reagent-modified NMR spectra display three 23Na signals representing sodium outside the vesicles, sodium within the vesicular water pools, and sodium within the membranes themselves. Copyright
Contiguous versus segmented hydrophobicity in micellar systems
Menger, Fredric M.,Galloway, Ashley L.
, p. 15883 - 15889 (2007/10/03)
This paper addresses a question not yet posed systematically in surfactant chemistry: How do the colloidal properties of surfactants respond to insertion of non-hydrocarbon functionalities (i.e., ester groups) within chains that are normally entirely hydrocarbon? In answering this question, two classes of such chain-modified surfactants were discovered. One class forms only small aggregates with noncooperative self-assembly, low foaming, high areas of occupancy at the air/water interface, and weak solid-adsorption and solubilization properties. The other class is much more normal with regard to these properties and, in fact, can even exceed conventional surfactants in mesitylene solubilization. Differences between the two categories of chain-modified surfactants originate from the degree of segmentation of the hydrocarbon and, in particular, upon the location of the longest segment. Segmented hydrophobicity, having in principle a "hydrophobic potential" similar to that of a contiguous hydrophobicity of equal length, can induce aggregation but, concurrently, alters the mode of assembly into films and micelles.
