Our Publications Database

Human Erythrocyte-Membrane; Optical Tweezers; Deformability; Manipulation; Mechanics; System

The stretching stiffness of Red Blood Cells (RBCs) was investigated using a combination of an AC dielectrophoretic apparatus and a single-beam optical tweezer. The experiments were performed at 10 MHz, a frequency high enough to avoid conductivity losses, but below the second turnover point between positive and negative dielectrophoresis. By measuring the geometrical parameters of single healthy human RBCs as a function of the applied voltage, the elastic modulus of RBCs was determined (mu = 1.80 +/- 0.5 mu N/m) and compared with similar values of the literature got by other techniques. The method is expected to be an easy-to-use, alternative tool to determine the mechano-elastic properties of living cells, and, on this basis, to distinguish healthy and diseased cells (C) 2014 Optical Society of America

Irinotecan; Drug delivery; Cytotoxicity; Mesoporous silica; MCM-41

Three mesostructured silica-type carriers, MCM-41 and MCM-41 functionalized by a postsynthesis grafting procedure with hydrophilic aminopropyl groups (MCM-APTES) and hydrophobic vinyl moieties (MCM-VTES), respectively, were investigated in order to elaborate drug delivery systems (DDS) for irinotecan molecules. All studied drug delivery systems exhibited higher cytotoxicity on murine embrionary fibroblastic (MEF) cells than free irinotecan at the same content of the cytostatic agent, whereas no toxicity was observed for the three unloaded carriers. The cytotoxic effect of irinotecan loaded on MCM-41-type carriers continued to increase even 24 h after ceasing the cell exposure to the drug and remained significantly higher than that of free irinotecan. The cellular uptake of silica-type hybrids was investigated by labelling MCM-APTES with Rhodamine B. In the case of the studied DDS, an endocytotic mechanism was found to be involved in the cell uptake process, and it was used to explain the cytotoxicity differences between free irinotecan and drug loaded on MCM-41-type supports.

Plus modern organic-synthesis, Exposure system, Laurdan fluorescence, Fields, Membranes, Model

In this paper, a delivery system allowing simultaneous microwave heating and real-time spectrofluorometric measurements in biological systems is proposed and characterized. This system is used to investigate the phase behavior of lipid bilayers from about 15 C to 45 C. The delivery system is based on an open transverse electromagnetic (TEM) cell combined with a spectrofluorometer via an optical cable system. A numerical and experimental dosimetry of the delivery system is conducted. The Specific Absorption Rate (SAR) efficiency of the system is 26.1 +/- 2.1 W/kg/W. Spectrofluorometric measurements on Laurdan labeled small unilamellar vesicles (SUVs) are carried out. Generalized polarization (GP) of the SUV’s membrane is obtained from the fluorescence intensities measured at two emission wavelengths.

Magnetite nanoparticles, Drug delivery, OK cellsș biodistribution, Iron oxide, Cell membrane

The interaction of nanomaterials with cells and lipid bilayers is critical in many applications such as phototherapy, imaging and drug/gene delivery. These applications require a firm control over nanoparticle-cell interactions, which are mainly dictated by surface properties of the nanoparticles. The aim of this study was to investigate the interaction of Fe3O4 nanoparticles functionalized with several wide use antibiotics with opossum kidney (OK) cellular membranes in order to reveal changes in the membrane organization at different temperatures. We also investigated the in vivo biodistribution of the tested nanoparticles in a mouse model. Our results showed that, at low temperatures (31-35°C), plain Fe3O4 nanoparticles induced a drop of the membrane fluidity, while at physiological or higher temperatures (37-39°C) the membrane fluidity was increased. On the other hand, when nanoparticles functionalized with the tested antibiotics were used, we observed that the effect was opposite as compared to control Fe3O4 nanoparticles. Although most of antibiotics, used as plain solutions or linked on magnetite nanoparticles, proved heterogeneous effect on in vitro OK cells membrane fluidity, the aminoglycosides streptomycin and neomycin, used both as plain solutions and also combined with nanoparticles kept the same effect in all experimental conditions, increasing the membrane fluidity of OK cells plasma membrane. In vivo results showed that the antibiotic functionalized nanoparticles have a similar biodistribution pattern within the mouse body, being transported through the blood flow and entering the macrophages through endocytosis. Functionalized magnetite nanoparticles manifested a preferential biodistribution pattern, clustering within the lungs and spleen of treated mice. These results demonstrate that antibiotics manifest a different effect on plasma membrane fluidity depending on their type and temperature. Magnetite nanoparticles may interfere with antibiotic-cellular interactions by changing the plasma membrane fluidity. The fact that the antibiotic functionalized magnetite nanoparticles have a similar biodistribution pattern, are transported through the blood flow, and they increase the cellular uptake of the drug, suggest that they may be used for further studies aiming to develop personalized targeted delivery and controlled release nanoshuttles for treating localized and systemic infections.

Chronic myeloid leukaemia, Reactive oxygen species, BCR/ABL Transcript, Platelet membrane, Platelet aggregation, Platelet receptors, Fluidity of platelet membrane

Patients with chronic myeloproliferative leukemia (CML) have frequent haemorrhage and/or thrombosis in their medical history. The mechanisms of these major and life-threatening complications remain unclear. Membrane organization influences many of the unique cellular functions and is strongly correlated, among other factors, to the membrane lipid composition; it may be evaluated by following up the membrane fluidity and aggregation properties of the platelet. In this study, we evaluated the platelet aggregation, the expression of platelet surface receptors, the membrane fluidity (as evaluated by fluorescence anisotropy) and its correlation to reactive oxygen species (ROS) production, in patients with chronic myeloid leukaemia (CML). It was found that the patients in accelerated and blastic phase of CML present an altered platelet aggregation response to all reagents except for ristocetin as compared with chronic phase group, which shows only epinephrine-altered response. We also found that BCR/ABL transcript leads to higher levels of ROS in accelerated and blastic CML phases. Patients without molecular remission have lower platelet membrane fluidity. We obtained a positive correlation between ROS level and membrane fluorescence anisotropy changes. The CD41 expression was decreased in CML patients and P selectin expression was found to be higher in these patients than in healthy volunteers. Platelets of CML patients have altered aggregation parameters in accelerated and blastic phases, in which BCR/ABL transcript level is increased. The increased level of ROS in CML patients without molecular remission is associated with a decrease in fluidity of platelet membrane and expression of CD41/CD61 receptors. These findings may contribute to understanding the mechanism of the altered platelet response reported in CML patients.