WATER SORPTION THERMODINAMICS IN PHOSPHATIDILCHOLINES LIPID MATRIXES AT DIFFERENT STATES ASSESSED BY FTIR-ATR SPECTROSCOPY

A. S. ROSA; E. A. DISALVO; FRIAS, M DE LOS ANGELES

La Plata- Modalidad Virtual

Congreso; XXII Congreso Argentino de Fisicoquimica y química inorgánica; 2021

Asociacion Argentina de investigacion fisicoquimica

Water sorption characteristics are reflective of the chemical and structural composition of lipid membranes and the temperature at which hydration takes place. Changes in the sorption characteristics with temperature and hydration level suggest that water induces structural changes that can be confirmed with molecular vibration frequencies by FTIR-ATR techniques. FTIR is a suitable technique to study and differentiate the structural changes that take place during water sorption in a lipid membrane. Different phospholipids associate water at particular modes according to their structures; this may produce modulation of packing and hydration suitable for the incorporation of aminoacids, peptides and enzymes1. Water sorption in lipids can take place at different sites characterized by different affinities: strong binding related to Phosphate and Carbonyl groups, weak ones related to confined water between acyl chains1, and water binding to already adsorbed water molecules. In this work water sorption isotherms were performed for DPPC and DOPC, at gel and liquid crystalline states, respectively. The spectroscopic analysis shows distinct responses of the different sorption sites along the sorption process at membrane states. Data were fitted using the D?Arcy Watt sorption model to each of the hydration sites, such as PO2, CH2 and CO to compare binding sites parameters (Figure 1). In this regard, it was found that water structure response is also particularly specific for each lipid.