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AKB: Biologische Physik

AKB 40: Poster Session II

AKB 40.28: Poster

Mittwoch, 29. März 2006, 16:30–19:30, P3

Highly oriented liquid water within the cationic lipid DODAB — •Lydia Woiterski¹, Josef A. Käs¹, David W. Britt², and Carsten Selle¹ — ¹Institute of Experimental Physics I, University of Leipzig, Linnestraße 5, D-04103 Leipzig,Germany — ²Department of Bioengineering, University of Utah, Salt L ake City, UT , 84112, USA

Cationic lipid membranes spontaneously form complexes with DNA. Therefore, cationic synthetic lipids are widely used for the preparation of gene transfection systems.

We performed a fundamental attenuated total reflection (ATR) Fourier-Transform infrared (FTIR) spectroscopic study on the phase behavior and hydration properties of the cationic lipid dioctadecyldimethylammonium bromide (DODAB).

A unique shape of the ν(OH)-absorption band was detected that arises from liquid water in the vicinity of the polar lipid headgroup. Six subbands of the OH-absorption can be assigned to different populations of highly oriented water molecules. Furthermore, the spectroscopic properties of the headgroup bound water were observed to be strongly sensitive to the halide counterion present.

Another newly found feature of DODAB is a drastic change in the ν(CNC)-absorption which is attributed to a strong conformational alteration in one of the alkyl chains when the water is completely removed.