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In order to prepare optimal platelet and extracellular vesicle (EV)-rich plasma for the treatment of chronic temporal bone inflammation, we studied effects of centrifugation parameters on redistribution of blood constituents in blood samples of 23 patients and 20 volunteers with no record of disease. Concentrations of blood cells and EVs were measured by flow cytometry. Sample content was inspected by scanning electron microscopy. A mathematical model was constructed to interpret the experimental results. The observed enrichment of plasma in platelets and EVs after a single spin of blood depended on the erythrocyte sedimentation rate, thereby indicating the presence of a flow of plasma that carried platelets and EVs in the direction opposite to settling of erythrocytes. Prolonged handling time correlated with the decrease of concentration of platelets and larger EVs in platelet and EV-rich plasma (PVRP), R = -0.538, p = 0.003, indicating cell fragmentation during the processing of samples. In further centrifugation of the obtained plasma, platelet and EV enrichment depended on the average distance of the sample from the centrifuge rotor axis. Based on the agreement of the model predictions with observations, we propose the centrifugation protocol optimal for platelet and EV enrichment and recovery in an individual sample, adjusted to the dimensions of the centrifuge rotor, volume of blood and erythrocyte sedimentation rate.[Figure: see text].

We report the study of optical textures and director configurations within nematic-in-water microdroplets of the liquid-crystalline mixtures based on azoxybenzene and cyanobiphenyl (as a polar dopant). Both pure azoxybenzene and polar dopant materials exhibited bipolar configuration within liquid-crystalline droplets, whereas their mixtures at appropriate concentrations spontaneously formed radial droplets. It was found that increasing of the dopant’s concentration resulted in the forward tangential-homeotropic and reentrant homeotropic-tangential anchoring transitions. We also triggered bipolar-to-radial structural transition by UV irradiation providing trans-cis isomerisation of nematogens. Critical irradiation time needed for radial configuration formation was found to decrease with concentration of polar dopant. Mesoscoping modelling is proposed to explain main experimental results. The presented data are discussed for chemical and biological sensing applications.

Experimental study of the behaviour of the shape of vesicles with long tubular protrusions (tethers), connected to them in non-symmetrical isoosmolar and non isoosmolar environment was performed. I...

Due to oxidation and adsorption of chloride and hydroxyl anions, the surface of titanium (Ti) implants is negatively charged. A possible mechanism of the attractive interaction between the negatively charged Ti surface and the negatively charged osteoblasts is described theoretically. It is shown that adhesion of positively charged proteins with internal charge distribution may give rise to attractive interaction between the Ti surface and the osteoblast membrane. A dynamic model of the osteoblast attachment is presented in order to study the impact of geometrically structured Ti surfaces on the osteoblasts attachment. It is indicated that membrane-bound protein complexes (PCs) may increase the membrane protrusion growth between the osteoblast and the grooves on titanium (Ti) surface and thereby facilitate the adhesion of osteoblasts to the Ti surface. On the other hand, strong local adhesion due to electrostatic forces may locally trap the osteoblast membrane and hinder the further spreading of osteointegration boundary. We suggest that the synergy between these two processes is responsible for successful osteointegration along the titanium surface implant.

It is believed that in regulated exocytosis the vesicle membrane fuses with the plasma membrane in response to a physiological stimulus. However, in the absence of stimulation, repetitive transient fusion events are also observed, reflecting a stable state. The mechanisms by which the initial fusion pore attains stability are poorly understood. We modelled energetic stability of the fusion pore by taking into account the anisotropic, intrinsic shape of the membrane constituents and their in-plane ordering in the local curvature of the membrane. We used cell-attached membrane capacitance techniques to monitor the appearance and conductance of single fusion pore events in cultured rat lactotrophs. The results revealed a bell-shaped distribution of the fusion pore conductance with a modal value of 25 pS. The experimentally observed increase of the fusion pore stability with decreasing fusion pore radius agrees well with the theoretical predictions. Moreover, the results revealed a correlation between the amplitude of transient capacitance increases and the fusion pore conductance, indicating that larger vesicles may attain a stable fusion pore with larger fusion pore diameters.

The elastic properties of a thin anisotropic nano‐strip are characterized by its intrinsic mean curvature and intrinsic curvature deviator. It is shown that minimization of the elastic energy of the strip including the deviatoric contribution may explain the stability of the observed helical and twisted shapes of inorganic nano‐strips (helix A and B).

Aged HS erythrocytes with a defined primary defect in band 3 protein or ankyrin were incubated with amphiphiles (detergents) at sublytic concentrations (37 C, 60 min) or glucose-starved (37 C, 24 h). In line with previous studies, the release of AChE (exovesicles) from HS erythrocytes during glucose-starvation was significantly higher (11%) compared to that from control erythrocytes (1%). Control and HS cells responded, however, similarly to amphiphile-treatment (non-starving conditions). Amphiphiles induced similar types of shape alterations and a similar amount of AChE release (14-15%). Furthermore, the size and shape of amphiphile-induced exo- and endovesicles released from control and HS erythrocytes were similar. The results suggest that the stability properties of the membrane are not seriously disturbed in aged HS erythrocytes under non-starving conditions.

Dalija Jesenek,1 ŠárkaPerutková,2 Wojciech Góźdź,3 Veronika Kralj-Iglič,4 Aleš Iglič,2,5 Samo Kralj1,61Condensed Matter Physics Department, Jožef Stefan Institute, Ljubljana, Slovenia; 2Laboratory of Biophysics, Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia; 3Department of Complex Systems and Chemical Processing of Information, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland; 4Laboratory of Clinical Biophysics, Faculty of Health Studies, University of Ljubljana, Ljubljana, Slovenia; 5Laboratory of Clinical Biophysics, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia; 6Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Maribor, SloveniaAbstract: Membrane budding often leads to the formation and release of microvesicles. The latter might play an important role in long distance cell-to-cell communication, owing to their ability to move with body fluids. Several mechanisms exist which might trigger the pinching off of globular buds from the parent membrane (vesiculation). In this paper, we consider the theoretical impacts of topological defects (frustrations) on this process in the membranes that exhibit global in-plane orientational order. A Landau–de Gennes theoretical approach is used in terms of tensor orientational order parameters. The impact of membrane shapes on position and the number of defects is analyzed. In studied cases, only defects with winding numbers m = ±1/2 appear, where we refer to the number of defects with m = 1/2 as defects, and with m = –1/2 as anti-defects. It is demonstrated that defects are attracted to regions with maximal positive Gaussian curvature, K. On the contrary, anti-defects are attracted to membrane regions exhibiting minimal negative values of K. We show on membrane structures exhibiting spherical topology that the coexistence of regions with K > 0 and K < 0 might trigger formation of defect–anti-defect pairs for strong enough local membrane curvatures. Critical conditions for triggering pairs are determined in several demonstrative cases. Then the additionally appeared anti-defects are assembled at the membrane neck, where K < 0. Consequent strong local fluctuations of membrane constituent anisotropic molecules might trigger membrane fission neck rupture, enabling a membrane fission process and the release of membrane daughter microvesicles (ie, vesiculation).Keywords: structural transitions, topological defects, membrane microvesicles, membrane curvature, membrane fission, vesiculation

Ekaterina Gongadze1, Doron Kabaso2, Sebastian Bauer3, Tomaž Slivnik2, Patrik Schmuki3, Ursula van Rienen1, Aleš Iglič21Institute of General Electrical Engineering, University of Rostock, Rostock, Germany; 2Laboratory of Biophysics, Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, Slovenia; 3Department of Materials Science, Friedrich-Alexander University of Erlangen-Nurenberg, Erlangen, GermanyAbstract: This work considers the adhesion of cells to a nanorough titanium implant surface with sharp edges. The basic assumption was that the attraction between the negatively charged titanium surface and a negatively charged osteoblast is mediated by charged proteins with a distinctive quadrupolar internal charge distribution. Similarly, cation-mediated attraction between fibronectin molecules and the titanium surface is expected to be more efficient for a high surface charge density, resulting in facilitated integrin mediated osteoblast adhesion. We suggest that osteoblasts are most strongly bound along the sharp convex edges or spikes of nanorough titanium surfaces where the magnitude of the negative surface charge density is the highest. It is therefore plausible that nanorough regions of titanium surfaces with sharp edges and spikes promote the adhesion of osteoblasts.Keywords: osteoblasts, nanostructures, adhesion, titanium implants, osteointegration