Glass transition temperature of water confined in lipid membranes as determined by anelastic spectroscopy

The research of gene delivery vehicles used in gene therapy is focused on nonviral vectors like lipid membranes. Such vectors, nonimmunogenic and biodegradable, are formed by complexation of DNA with a mixture of cationic lipids and a neutral colipid which improve the transfection efficiency. A main topic related to lipid membrane dynamics is their capability to spontaneously confine water. At present the value of the glass transition temperature (T-g) is largely debated and determined only by some indirect methods. Here the authors show that anelastic spectroscopy allows the confined water T-g value to be directly identified in several lipid mixtures. (c) 2006 American Institute of Physics.