Aqueous phase behavior of lipids with isoprenoid type hydrophobic chains.

Aqueous phase behavior of lipids with isoprenoid type hydrophobic chains (hereafter referred to as "isoprenoid-chained lipids") as functions of the chain length and the hydrophilic headgroup type has been examined over a chain length span from 12 to 16 carbon atoms long and a temperature range from -40 to 65 degrees C by using optical microscopy, DSC (differential scanning calorimetry), and SAXS (small-angle X-ray scattering) techniques. Characteristic phase behavior that arises from the unique "isoprenoid-chain" structure was discussed. This work together with previous studies (Prog. Colloid Polym. Sci. 2004, 123, 56-60 and J. Phys. Chem. B 2008, 112, 12286-12296) has clarified the molecular correlation of the aqueous phase behavior of "isoprenoid-chained lipids" over the chain lengths from 12 to 18 carbon atoms and introduced a new lipid library which can form a range of liquid crystals, such as an HII (an inverted hexagonal phase), a QII (an inverted cubic phase), and an Lalpha (a lamellar phase), that are stable over a wide temperature span from 0 degrees C.