Ionic properties of phospholipids at the oil/water interface

✍ Scribed by Makoto Hayashi; Takonori Kobayashi; Tsutomu Seimiya; Toshio Muramatsu; Ichiro Hara

• Publisher: Elsevier Science
• Year: 1980
• Tongue: English
• Weight: 345 KB
• Volume: 27
• Category: Article
• ISSN: 0009-3084
• DOI: 10.1016/0009-3084(80)90043-2

✦ Synopsis

Surface pressures and surface viscosities of dipalmitoylphosphatidylethanolamine and its polar group analogues were measured at the hexane/water interface as a function of bulk pH. The monolayers expanded as the bulk pH was shifted from neutral to alkaline and gave rise to an increase in surface pressure at a constant area, and the surface viscosity was simultaneously reduced at high pH. For the increase in surface pressure, theoretical values were calculated using the Gouy-Chapman equation for the electrical double layers produced by shifting pH, and good agreements were obtained with the measured ones from which a simple mechanism was deduced for the increase in pressure. The ionic dissociation characteristics of amino groups of the lipids were discussed taking pKa values given in the above calculations into account. The reduction of the surface viscosity was thought to be attributable to disintegration of zwitter ionic structure in the condensed monolayers.