Near infrared spectroscopy and multivariate analysis for the study of water in lipidic membranes

Abstract

The ability of near infrared spectroscopy to inform about the vibrations of the covalent O-H, by means of the 11 first overtone of water around 1450/55 nm, was exploited to examine the water in membranes and the influence 12 of the constitutive phospholipids on hydrogen bonding. The less the number and/or the strength of H-bonds, the 13 more the strength of the O-H bonds and so they vibrate and absorbs radiation at higher frequencies. This shift is 14 employed to evaluate the water status in membranes composed of two phospholipids having the same acyl chain 15 but different polar head, the part of the molecule typically associated in the interaction with water.