THE NEUTRAL AREA SURFACE OF THE CUBIC MESOPHASE - LOCATION AND PROPERTIES

A neutral area surface can be defined as one whose area remains fixed upon bending. It is assumed that such a surface exists within the amph iphilic monolayers that constitute the bicontinuous cubic mesophases a nd that it parallels approximately the highly convoluted polar/apolar interlace in such systems. Here, we report on how the neutral area sur face in the cubic phase (space group la3d) of the hydrated monoacylgly cerol, monoolein, was determined. It is located at a distance of simil ar to 8.8 Angstrom from the methyl terminus of the acyl chain. At 25 d egrees C, the surface area per lipid molecule at the neutral area surf ace is 35.1 +/- 0.2 Angstrom(2), which is remarkably similar to the me an cross-sectional area of hydrated monoolein in the lamellar liquid c rystalline phase at this same temperature.