The hydration of DMPC vesicles surfaces with the addition of Trition X-100 surfactant

Vesicles of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) have been measured by spin-probe partitioning electron paramagnetic resonance (SPPEPR), allowing for the study of the dynamics of lipid structures. By incorporating SPPEPR from numerous experiments, we have been able to extract parameters that give insight into the physics of the hydration layer of the DMPC vesicles. Measurements are described as consisting of two parts: an aqueous phase and a lipid phase. The two phase systems are taken as a superposition second-harmonic spectra of the hyperfine interactions of the spin probe ditert-butyl nitroxide (DTBN) with the surroundings. Measurements of DMPC with different molar fractions of Triton X-100 (C14H220(C2H4 0)11 ) non-ionic surfactant were analyzed using SPPEPR. With the use of non-linear least square fitting the second harmonic spectra was separated from the two phases that are aqueous and lipid, and into two respective Lorentzian signals. The hyperfine interactions of the DMPC-Triton system were then interpreted from the Lorentzians to give insight to the hydration layer of the vesicles, as the molar fraction of the Triton X-100 are changed. The results of non-linear square fitting to SPPEPR spectrum show that changing the molar fraction of Triton X- 100 has a direct correlation with changes in hydration of the hydration layer