the changes detected by polarity sensitive fluorescent probes
The effect of different parameters on the interfacial polarity placed at the interfacial level. The study is done using two of phospholipid vesicles was studied using two polarity-sensitive molecular probes, dansyldihexadecylamine (DA) and danfluorescent probes, dansyldihexadecylamine (DA) and dansylsylphosphatidylethanolamine (DPE).
phosphatidylethanolamine (DPE). The analysis was based on the
The current method used to evaluate interface polarity by Stokes shift and steady-state fluorescence anisotropy changes with means of polarity sensitive fluorescent probes is to measure different parameters. The influence of surface curvature, lipid the Stokes shift (S). S is defined by composition, and surface charge density was analyzed in small and large unilamellar vesicles and in multilamellar vesicles at different temperatures and in different lipid phase states. The S Å 1 l max exc 0 1 l max emis , [1] membranes showed significant polarity, packing constraints, and hydration degree changes at the polar head level when different variables were imposed. The comparative analysis of the probe where l max exc and l max emis are the wavelengths (in cm) of the response demonstrates that each dansyl derivative yields different maximum of the excitation and the emission spectra, respecinformation about membrane changes. DA appears to be more tively. sensitive to packing constraints and hydration, probably due to its molecular structure and location at the interface level. DPE
In homogeneous solutions S can be correlated to the static seems to sense polarity values averaged in the region where its dielectric constant (e s ) and the high-frequency dielectric polar head can pivot, and is, as expected, susceptible to electroconstant (e ϱ ) of the solvent through the Lippert-Mataga static interactions.