Electrochemical Investigation of the Stability of Poly-Phosphocholinated Liposomes.

Poly[2-(methacryloyloxy)ethyl phosphorylcholine] liposomes (pMPC liposomes) gained attention during the last few years because of their potential use in treating osteoarthritis. pMPC liposomes that serve as boundary lubricants are intended to restore the natural lubrication properties of articular cartilage. For this purpose, it is important that the liposomes remain intact and do not fuse and spread as a lipid film on the cartilage surface.

Change in Osmotic Pressure Influences the Absorption Spectrum of Hemoglobin inside Red Blood Cells.

Absorption spectra of red blood cell (RBC) suspensions are investigated in an osmolarity range in the medium from 200 mOsm to 900 mOsm. Three spectral parameters are used to characterize the process of swelling or shrinkage of RBC-the absorbance at 700 nm, the Soret peak height relative to the spectrum background, and the Soret peak wavelength. We show that with an increase in the osmolarity, the absorbance at 700 nm increases and the Soret peak relative height decreases.

Radiofrequency dielectric spectroscopy study: Effects of pH, hydrogen bond donors and acceptors on the attachment of spectrin skeleton to the lipid membrane of erythrocytes.

Band 3 protein and glycophorin C are the two major integral proteins of the lipid membrane of human red blood cells (RBCs). They are attached from below to a network of elastic filamentous spectrin, the third major RBC membrane protein. The binding properties of the attachments to spectrin affect the shape and deformability of RBCs.

Hemolysis by Saponin Is Accelerated at Hypertonic Conditions.

Saponins are a large group of organic amphiphilic substances (surfactants) mainly extracted from herbs with biological activity, considered as one of the main ingredients in numerous remedies used in traditional medicine since ancient times. Anti-inflammatory, antifungal, antibacterial, antiviral, antiparasitic, antitumor, antioxidant and many other properties have been confirmed for some. There is increasing interest in the elucidation of the mechanisms behind the effects of saponins on different cell types at the molecular level.

Role of Plasma Membrane at Dielectric Relaxations and Intermembrane Interaction in Human Erythrocytes.

Dielectric relaxations at 1.4 MHz (β) and 9 MHz (γ1) on the erythrocyte spectrin network were studied by dielectric spectroscopy using dense suspensions of erythrocytes and erythrocyte ghost membranes, subjected to extraction with up to 0.2% volume Triton-X-100.

Segmental flexibility of spectrin reflects erythrocyte membrane deformability.

The frequency-dependent contribution of spectrin, the main cytoskeletal protein of red blood cell (RBC) membrane, to the complex admittance and capacitance of suspended RBCs have revealed two dielectric relaxations, βsp (1.4 MHz) and γ1sp (7 MHz). The strength of these relaxations was related to the ability of RBC membrane to deform.

Differential dielectroscopic data on the relation of erythrocyte membrane skeleton to erythrocyte deformability and flicker.

Two dielectric relaxations, β (1.5 MHz) and γ1 (7 MHz), have been detected on spectrin-based membrane skeleton (MS) of red blood cells (RBCs) using the plot of admittance changes at the spectrin denaturation temperature (Ivanov and Paarvanova in Bioelectrochemistry 110: 59-68, 2016, Electrochim Acta 317: 289-300, 2019a). In this study, we treated RBCs and RBC ghost membranes with agents that make membranes rigid and suppress membrane flicker, and studied the effect on β and γ1 relaxations.

Species-dependent variations in the dielectric activity of membrane skeleton of erythrocytes.

Previously detected βsp and γ1sp dielectric relaxations on the spectrin-based membrane skeleton (MS) of human red blood cells (RBCs) have been shown sensitive to the attachment of MS to the lipid-protein membrane. Such relaxations were now detected on the MS of mammal (rat, horse, bovine, sheep and goat) and "unstrained" chicken RBCs. To become "unstrained" chicken RBCs were subjected consecutively to cold (4°C, >20 h) and either colchicine (15 mM) or vinblastine (30 μM) (4°C, 1 h) that led to irreversible disassembly of their marginal band and an additional portion of their cytoskeleton.

Effects of heat and freeze on isolated erythrocyte submembrane skeletons.

In this study we heated insoluble residues, obtained after Triton-X-100 (0.1 v/v%) extraction of erythrocyte ghost membranes (EGMs). Specific heat capacity, electric capacitance and resistance, and optical transmittance (280 nm) sustained sharp changes at 49°C (TA) and 66°C (TC), the known denaturation temperatures of spectrin and band 3, respectively.