Dielectric Properties of Phosphatidylcholine Membranes and the Effect of Sugars

Abstract

Simple carbohydrates are associated with the enhanced risk of cardiovascular disease and adverse changes in lipoproteins in the organism. Conversely, sugars are known to exert a stabilizing effect on biological membranes, and this effect is widely exploited in medicine and industry for cryopreservation of tissues and materials. In view of elucidating molecular mechanisms involved in the interaction of mono- and disaccharides with biomimetic lipid systems, we study the alteration of dielectric properties, the degree of hydration, and the rotational order parameter and dipole potential of lipid bilayers in the presence of sugars. Frequency-dependent deformation of cell-size unilamellar lipid vesicles in alternating electric fields and fast Fourier transform electrochemical impedance spectroscopy are applied to measure the specific capacitance of phosphatidylcholine lipid bilayers in sucrose, glucose and fructose aqueous solutions. Alteration of membrane specific capacitance is reported in sucrose solutions, while preservation of membrane dielectric properties is established in the presence of glucose and fructose. We address the effect of sugars on the hydration and the rotational order parameter for 1-palmitoyl-2-oleoyl-sn-glycero-3- phosphocholine (POPC) and 1-stearoyl-2-oleoyl-sn-glycero-3- phosphocholine (SOPC). An increased degree of lipid packing is reported in sucrose solutions. The obtained results provide evidence that some small carbohydrates are able to change membrane dielectric properties, structure, and order related to membrane homeostasis. The reported data are also relevant to future developments based on the response of lipid bilayers to external physical stimuli such as electric fields and temperature changes.

Erythrocyte Membrane Biophysical Changes Mediated by Pooled Immunoglobulin G and Hematin: Electrokinetic and Lipid Peroxidation Studies

“…We studied the effect of melittin on the electrical properties of bilayer lipid membranes (BLM) formed via the Montal–Mueller method [ 30 , 31 ] from egg-yolk L-α-phosphatidylcholine. Pentane CH 3 (CH 2 ) 3 CH 3 and hexane CH 3 (CH 2 ) 4 CH 3 of HPLC grade were used for dissolving the lipid.…”

“…The Montal–Mueller chamber, model BC-20A, was provided by Eastern Scientific LLC (Rockville, MD, USA). Solvent-free bilayers were obtained suspended on the aperture with a diameter of 100 µm in a 0.025 mm thin Teflon membrane according to the corresponding protocol [ 30 ] as described in detail in [ 31 ]. The final control of the bilayer formation and its quality were verified electrically [ 32 ].…”

“…The capacitance and resistance of the planar lipid membrane were deduced from the analysis of the acquired FFT-EIS data taking into account the equivalent circuit representing the Montal–Mueller BLM configuration as discussed in [ 31 ]. The membrane specific capacitance and resistance were calculated from the measured capacitance and resistance of the bilayer and its 100 µm-circle surface area 8 × 10 −5 cm 2 .…”

Valorphins alter physicochemical characteristics of phosphatidylcholine membranes: Datasets on lipid packing, bending rigidity, specific electrical capacitance, dipole potential, vesicle size

“…Laurdan and Di-8-ANEPPS fluorescence spectroscopy measurements were carried out on suspensions of large unilamellar vesicles (LUV), obtained by a LiposoFast small-volume extruder equipped with polycarbonate filters (Avestin, Ottawa, Canada) [5] . Laurdan-labelled samples contained 1:200 probe:lipid molar ratio.…”

“…Dynamic light scattering and laser Doppler electrophoresis of large unilamellar vesicles were acquired by Zetasizer Advance Series Instrument (Malvern Analytical, United Kingdom) with a 4 mW 632.8 nm sample illumination and detection at 173°. Fluorescence spectroscopy data of dye-labelled membranes (FP-8300, Jasco, MD, USA) refer to Laurdan spectra recorded from 390 to 600 nm upon excitation at 355 nm, and to di-8-ANEPPS fluorescence intensity ratio at 670 nm upon excitation at 420 nm and 520 nm [5] . Data format Raw Data Analyzed Data Description of data collection The values of the bending modulus reported in the present article were calculated from ATSF data on populations of 6 to 13 GUVs accepted according to algorithms applied for elimination of systematic artifacts including correlated contours, volume and surface changes, non-quasisphericity, blurred contours, and membrane defects [2] .…”