Rehydration of digalactosyldiacylglycerol model membrane lyophilizates observed by NMR and sorption isotherm

Abstract

The initial stages of rehydration of digalactosyldiacylglycerol model membrane lyophilizates were observed using hydration kinetics, sorption isotherm, and high power proton relaxometry (at 30 MHz). Hydration time courses are single exponential and the sorption isotherm is sigmoidal in form. The mass of water saturating primary binding sites equals ΔM/m0 = 0.019 ± 0.001. Proton free induction decays distinguish (i) immobilized protons of solid matrix of lyophilizate, signal So; (ii) protons of water fraction tightly bound to the lyophilizate surface, L1; and (iii) mobile protons of loosely bound water pool, L2. Hydration dependence of total water signal (L1 + L2)/S0 shows the presence of water fraction "sealed" in liposome structures, which equals ΔMS/m0 = 0.092 ± 0.007.