Glycocalyx Research Articles

The amoebae of Idionectes vortex (Cutosea, Amoebozoa): Motility, cytoskeleton architecture and extracellular scales.

The Cutosea represent a deep-branching lineage within the phylum Amoebozoa that is still relatively poorly explored. Currently, there are four cutosean representatives known - the monotypic genera Armaparvus, Idionectes, Sapocribrum, and Squamamoeba - with marked genetic distances. Idionectes vortex is the deepest-branching species and differs markedly from the other Cutosea in ecology, life history, and most importantly, in its ability to form a flagellated swarmer with an exceptional swimming mechanism. As far as we know, the other Cutosea lack flagella and rather represent small, marine amoebae with a characteristic cell coat. The present paper focuses on the amoeboid life history stage of the algivorous amoeboflagellate Idionectes vortex to provide data for a first in-depth comparison with other Cutosea and to document structural specialties. The amoeboid stage of Idionectes is mainly associated with the specific feeding process, that is, the interaction with algal prey cells and phagocytosis of protoplast material. Yet, the present data from time-lapse microscopy, cytochemical stainings, and electron microscopy demonstrate clear similarities with the other cutosean species concerning amoeboid locomotion and cell coat ultrastructure. Furthermore, Idionectes amoebae exhibit a well-developed microtubular cytoskeleton, and an unusual basal apparatus that seems to undergo marked changes during the life history of this exceptional amoebozoan.

Abstract 120: Pericytes Contribute To Myofibroblast Expansion And Vascular Maturation In The Infarcted Heart

Infarct healing is dependent on recruitment of inflammatory leukocytes and subsequent activation of myofibroblasts (MF) and neovessel formation, ultimately resulting in formation of a highly vascularized collagen-enriched scar. Though the heart has an abundant population of periendothelial pericytes, its role in wound healing upon myocardial infarction (MI) has not been studied. We hypothesized that in the infarcted myocardium, pericytes may become activated, contributing to inflammatory, fibrotic and angiogenic responses. We used pericyte/fibroblast reporter mice (NG2 DsRed ;PDGFRα GFP ), lineage tracing studies and in vitro approaches to study the fate and role of pericytes in the infarcted myocardium. In normal hearts, NG2+/PDGFRα- pericytes and PDGFRα+/NG2- fibroblasts had distinct transcriptomic profiles. Pericytes expressed mural genes like Acta2 , Pdgfrb and low amounts of extracellular matrix (ECM) genes, whereas fibroblasts synthesized collagens, Timp2/3 and matricellular genes. 7 days post-MI, expansion of the NG2+ population in the infarct zone was associated with emergence of non-mural NG2+/αSMA+ cells with MF characteristics. FACS-sorted NG2+/PDGFRα- cells from 7-day infarcts expressed higher levels of collagens when compared to NG2+/PDGFRα- cells from normal hearts. Infarct pericytes had high integrin and MMP14 expression, reflecting an activated migratory phenotype. Lineage tracing using NG2CreER TM ;Rosa tdTomato ;PDGFRα GFP mice showed that 5.7%±1.04 of PDGFRα+ fibroblasts and 10.49%±2.73 of infarct MFs were derived from NG2+ lineage. Pericyte-derived fibroblasts exhibited higher ECM gene synthesis, in comparison to fibroblasts from non-pericyte origin, while pericyte-derived mural cells showed accentuated inflammatory cytokine gene expression. Immunostaining showed pericytes actively contribute to vascular maturation, forming a mural cell coat enwrapping infarct neovessels. In vitro, TGFβ induced integrins, collagens and MMPs in human pericytes, similar to the changes observed in infarct pericytes. Taken together, our evidences show that after MI, pericytes become activated and contribute to repair by undergoing conversion to a subset of myofibroblasts and by coating infarct neovessels.

Self-Cleaning Performance of Super-Hydrophilic Coatings for Dust Deposition Reduction on Solar Photovoltaic Cells

Dust deposition on solar photovoltaic (PV) cell surface will significantly decrease the PV power efficiency, as the transmittance of the solar cells would be greatly decreased by the deposited dust particles. This paper aims to study the anti-dust performance of super-hydrophilic coatings for the solar PV cells with water spraying condition. The solar cell covering glass was treated to be super-hydrophilic and compared with the bare glass sample. It was found that many dust particles adhere and aggregate on the uncoated glass while the particles deposited on the super-hydrophilic glass surface are densely distributed. When the water spraying process was conducted, the dust deposition mass for the bare and the coated glass samples are both reduced obviously with the increase time of water spraying. In addtion, dust deposition mass is significantly reduced with the increase of deposition and spraying tilt angles. The self-cleaning efficiency of super-hydrophilic coating on dust deposition is 92% higher than the bare glass cases. The spectral transmittance of glass samples for all the coated cases are significantly higher than that for all the bare cases. The maximum transmittance improvement can reach 26.5% when the deposition tilt angle is 30° and the spraying tilt angle is 60°.

Investigation of high potential corrosion protection with titanium carbonitride coating on 316L stainless steel bipolar plates

In order to improve the durability of stainless steel bipolar plates at high potential during the start-up/shut-down process of proton exchange membrane fuel cell (PEMFC), TiN and TiCN coatings with different C element contents are deposited on the 316L stainless steel substrates by using Closed Field Unbalanced Magnetron Sputter Ion Plating. The electrochemical test results show that the TiCN-2sccm sample possesses excellent corrosion resistance compared to other samples. The results of interfacial contact resistance (ICR) measurements show that the minimum ICR value of the TiCN-2sccm sample is 10 mΩ cm2, which meets the Department of Energy targets.

Effect of 3D-Fibroblast Dermis Constructed by Layer-by-Layer Cell Coating Technique on Tight Junction Formation and Function in Full-Thickness Skin Equivalent.

Human skin equivalents (HSEs) consisting of an epidermis and dermis have been used as promising tools for drug evaluation and for clinical applications in regenerative medicine. Normal human dermal fibroblasts (NHDFs) are essential for the fabrication of HSEs because they play an important role in the maturation of the epidermis. Recently, epidermal tight junctions (TJs), which are complex cell-cell junctions, have attracted much attention as a second barrier and regulator for other barrier functions. In a previous study, we revealed the expression of TJ-related proteins and the time course of formation of TJ structure in the HSE (layer-by-layer (LbL)-three-dimensional (3D) Skin) constructed by layer-by-layer (LbL) cell coating technique that have a unique dermis consisting of NHDFs only (3D-fibroblast dermis). However, the effect of the 3D-fibroblast dermis on the formation of functional epidermal TJs is unknown. In this study, we investigated the effect of the 3D-fibroblast dermis on the expression of TJ-related proteins and TJ function in LbL-3D Skin. We demonstrated that the 3D-fibroblast dermis affects the long-term expression of TJ-related proteins and the formation of TJ with barrier function in the epidermis. These results show that the 3D-fibroblast dermis in LbL-3D Skin contributes to the formation and maintenance of functional TJs as in native human skin by direct contact with KCs.

Glycocalyx is critical for blood-brain barrier integrity by suppressing caveolin1-dependent endothelial transcytosis following ischemic stroke.

The breakdown of the blood‐brain barrier (BBB) is related to the occurrence and deterioration of neurological dysfunction in ischemic stroke, which leads to the extravasation of blood‐borne substances, resulting in vasogenic edema and increased mortality. However, a limited understanding of the molecular mechanisms that control the restrictive properties of the BBB hinders the manipulation of the BBB in disease and treatment. Here, we found that the glycocalyx (GCX) is a critical factor in the regulation of brain endothelial barrier integrity. First, endothelial GCX displayed a biphasic change pattern, of which the timescale matched well with the biphasic evolution of BBB permeability to tracers within the first week after t‐MCAO. Moreover, GCX destruction with hyaluronidase increased BBB permeability in healthy mice and aggravated BBB leakage in transient middle cerebral artery occlusion (t‐MCAO) mice. Surprisingly, ultrastructural observation showed that GCX destruction was accompanied by increased endothelial transcytosis at the ischemic BBB, while the tight junctions remained morphologically and functionally intact. Knockdown of caveolin1 (Cav1) suppressed endothelial transcytosis, leading to reduced BBB permeability, and brain edema. Lastly, a coimmunoprecipitation assay showed that GCX degradation enhanced the interaction between syndecan1 and Src by promoting the binding of phosphorylated syndecan1 to the Src SH2 domain, which led to rapid modulation of cytoskeletal proteins to promote caveolae‐mediated endocytosis. Overall, these findings demonstrate that the dynamic degradation and reconstruction of GCX may account for the biphasic changes in BBB permeability in ischemic stroke, and reveal an essential role of GCX in suppressing transcellular transport in brain endothelial cells to maintain BBB integrity. Targeting GCX may provide a novel strategy for managing BBB dysfunction and central nervous system drug delivery.

The Endothelial Glycocalyx as a Double-Edged Sword in Microvascular Homeostasis and Pathogenesis.

Expressed on the endothelial cell (EC) surface of blood vessels, the glycocalyx (GCX), a mixture of carbohydrates attached to proteins, regulates the access of cells and molecules in the blood to the endothelium. Besides protecting endothelial barrier integrity, the dynamic microstructure of the GCX confers remarkable functions including mechanotransduction and control of vascular tone. Recently, a novel perspective has emerged supporting the pleiotropic roles of the endothelial GCX (eGCX) in cardiovascular health and disease. Because eGCX degradation occurs in certain pathological states, the circulating levels of eGCX degradation products have been recognized to have diagnostic or prognostic values. Beyond their biomarker roles, certain eGCX fragments serve as pathogenic factors in disease progression. Pharmacological interventions that attenuate eGCX degradation or restore its integrity have been sought. This review provides our current understanding of eGCX structure and function across the microvasculature in different organs. We also discuss disease or injury states, such as infection, sepsis and trauma, where eGCX dysfunction contributes to severe inflammatory vasculopathy.

Design and Optimization of the Antireflective Coating Properties of Silicon Solar Cells by Using Response Surface Methodology

The design and optimization of a nanostructured antireflective coatings for Si solar cells were performed by using response surface methodology (RSM). RSM was employed to investigate the effect on the overall optical performance of silicon solar cells coated with three different nanoparticle materials of titanium dioxide, aluminum oxide, and zinc oxide nanostructures. Central composite design was used for the optimization of the reflectance process and to study the main effects and interactions between the three process variables: nanomaterial type, the radius of nanoparticles, and wavelength of visible light. In this theoretical study, COMSOL Multiphysics was utilized to design the structures by using the wave optics module. The optical properties of the solar cell’s substrate and the three different nanomaterial types were studied. The results indicated that ZnO nanoparticles were the best antireflective coating candidate for Si, as the ZnO nanoparticles produced the lowest reflection values among the three nanomaterial types. The study reveals that the optimum conditions to reach minimum surface reflections for silicon solar cell were established by using ZnO nanoparticles with a radius of ~38 nm. On average, the reflectance reached ~5.5% along the visible spectral range, and approximately zero reflectance in the 550–600 nm range.

Antireflective Self-Cleaning TiO2 Coatings for Solar Energy Harvesting Applications

Titanium(IV) oxide (TiO2, titania) is well-known for its excellent photocatalytic properties, wide bandgap, chemical resistance, and photostability. Nanostructured TiO2 is extensively utilized in various electronic and energy-related applications such as resistive switching memory devices, flat panel displays, photodiodes, solar water-splitting, photocatalysis, and solar cells. This article presents recent advances in the design and nanostructuring of TiO2-containing antireflective self-cleaning coatings for solar cells. In particular, the energy harvesting efficiency of a solar cell is greatly diminished by the surface reflections and deposition of environmental contaminants over time. Nanostructured TiO2 coatings not only minimize reflection through the graded transition of the refractive index but simultaneously improve the device’s ability to self-clean and photocatalytically degrade the pollutants. Thus, novel approaches to achieve higher solar cell efficiency and stability with pristine TiO2 and TiO2-containing nanocomposite coatings are highlighted herein. The results are compared and discussed to emphasize the key research and development shortfalls and a commercialization perspective is considered to guide future research.

Efficient simulation of biperiodic, layered structures based on the T-matrix method

Predicting the optical response of macroscopic arrangements of individual scatterers is a computational challenge because the problem involves length scales across multiple orders of magnitude. We present a full-wave optical method to efficiently compute the scattering of light at objects that are arranged in biperiodic arrays. Multiple arrays or homogeneous thin films can be stacked to build up an entire multicomposite material in the third dimension. The scattering properties of the individual objects in each array are described by the T-matrix formalism. Therefore, arbitrarily shaped objects and even molecules can be the basic constituent of the arrays. Taking the T-matrix of the individual scatterer as the point of departure we can explain the optical properties of the bulk material from the scattering properties of its constituents. We use solutions of Maxwell’s equations with well-defined helicity. Therefore, chiral media are particularly easy to consider as materials for both scatterers and embedding media. We exemplify the efficiency of the algorithm with an exhaustive parametric study of anti-reflective coatings for solar cells made from cylinders with a high degree of helicity preservation. The example shows a speed-up factor of about 500 with respect to finite-element computations. A second example specifically exploits the use of helicity modes to investigate the enhancement of the circular dichroism signal in a chiral material.

Immuno-Electron and Confocal Laser Scanning Microscopy of the Glycocalyx.

Simple SummaryThe glycocalyx (GCX) is a hydrated, gel-like layer of biological macromolecules attached to the cell membrane. The GCX acts as a barrier and regulates the entry of external substances into the cell. The function of the GCX is highly dependent on its structure and composition. Pathogenic factors can affect the protective structure of the GCX. We know very little about the three-dimensional organization of the GXC. The tiny and delicate structures of the GCX are difficult to study by microscopic techniques. In this study, we evaluated a method to preserve and label sensitive GCX components with antibodies for high-resolution microscopy analysis. High-resolution microscopy is a powerful tool because it allows visualization of ultra-small components and biological interactions. Our method can be used as a tool to better understand the role of the GCX during the development and progression of diseases, such as viral infections, tumor invasion, and the development of atherosclerosis.The glycocalyx (GCX), a pericellular carbohydrate rich hydrogel, forms a selective barrier that shields the cellular membrane, provides mechanical support, and regulates the transport and diffusion of molecules. The GCX is a fragile structure, making it difficult to study by transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM). Sample preparation by conventional chemical fixation destroys the GCX, giving a false impression of its organization. An additional challenge is to process the GCX in a way that preserves its morphology and enhanced antigenicity to study its cell-specific composition. The aim of this study was to provide a protocol to preserve both antigen accessibility and the unique morphology of the GCX. We established a combined high pressure freezing (HPF), osmium-free freeze substitution (FS), rehydration, and pre-embedding immunogold labeling method for TEM. Our results showed specific immunogold labeling of GCX components expressed in human monocytic THP-1 cells, hyaluronic acid receptor (CD44) and chondroitin sulfate (CS), and maintained a well-preserved GCX morphology. We adapted the protocol for antigen localization by CLSM and confirmed the specific distribution pattern of GCX components. The presented combination of HPF, FS, rehydration, and immunolabeling for both TEM and CLSM offers the possibility for analyzing the morphology and composition of the unique GCX structure.

Hydrogel Coatings: Surface‐Triggered In Situ Gelation for Tunable Conformal Hydrogel Coating of Therapeutic Cells and Biomedical Devices (Adv. Funct. Mater. 21/2021)

In article number 2010169, Simmyung Yook, Jee-Heon Jeong, and co-workers develop a simple and facile method for conformal hydrogel coating of living cells, mini-organs, and biomedical devices. The thickness of the hydrogel layer can be precisely controlled from several to hundreds of micrometers. This method overcomes inevitable challenges in cell encapsulation and enables the engineering of 3D hydrogels for tissue engineering or delivery of therapeutic cells and drugs.

Dense nanostructured YSZ coating prepared by low-pressure suspension plasma spraying: Atmosphere control and deposition mechanism

Suspension plasma spraying (SPS) has attracted more and more attention in terms of the preparation of nanostructured ceramic coatings. However, due to the low mass of the nanopowder , it is challenging to prepare high-density coatings through SPS, and this largely limits its application in the areas such as electrolytes of solid oxides fuel cell (SOFC) and environmental barrier coatings. In this article, a novel suspension spraying technology – low-pressure suspension plasma spraying (LPSPS) – was used to prepare a high-density, nanostructured coating. The results revealed that the environment atmosphere (inert atmosphere versus oxidative atmosphere) played a critical role in the microstructure of the coating. The deposition mechanisms of the coatings in both atmospheres were proposed, and a high-density nanostructured yttria-stabilized zirconia (YSZ) coating was successfully prepared by atmosphere control, based on these deposition mechanisms. • A novel suspension spraying technique—low-pressure suspension plasma spraying was used to prepare dense nanostructured YSZ coating. • In the inert atmosphere, a number of carbons were produced in the plasma jet due to the ethanol pyrolysis, resulting in poor adhesion and mechanical properties of the coating • In the oxidative atmosphere, due to ethanol combustion, the plasma jet exhibited a better heating capacity for powders, resulting in improved quality of the coating. • A high-density YSZ coating was successfully prepared with a high-enthalpy plasma jet in the oxidative atmosphere

Effect of optical parameters on design of highly reflecting distributed Bragg reflectors based on compound semiconductors for space applications

Comprehensive model for the design of highly reflecting distributed Bragg reflectors (DBRs) is investigated for spectral band, ranging from ultraviolet to short wavelength infrared (SWIR). The reflectivity calculation is done using thin film multiple reflection technique. The variation of reflectivity as a function of wavelength, number of grown epilayers, angle of incidence and difference between refractive indices of constituent epilayers is examined. The target wavelengths for reflectivity simulation include 1.55 and 1.3 μm for optical communication, 850 and 980 nm for infrared (IR) imaging devices and chip-scale atomic clocks, and 412 and 443 nm for UV light emitting diodes and antireflection coatings for charge-coupled devices and solar cells. The reflectivity values calculated for compound semiconductor DBRs lie between 95 and 99%. It is also inferred that the reflectivity of grown epilayers and broadness of operational spectrum increases with number of epilayers. If DBR stack is grown on lattice mismatched substrate, increment of the reflectivity is found only at single wavelength. As the angle of incidence increases from 0° to 80°, blue shift in reflectance (towards low wavelength) is also observed. The increase in reflectivity is also observed with increase in difference in refractive indices of epilayers.

Pressure assisted flash sintering of Mn-Co based spinel coatings for solid oxide electrolysis cells (SOECs)

Pressure assisted flash sintering was used to process Mn-Co-Cu based spinel coatings, electrophoretically deposited on a Crofer22APU interconnect. This method resulted in highly dense coatings, heat-treated for only a short duration (<10 min) at temperatures lower than conventional sintering temperatures. The electrophoretically deposited coatings showed no delamination or cracks after flash sintering at high heating rates (>200 °C/min). The high heating rate promoted Cu modified Mn-Co spinel and limited the formation of a Cr-oxide scale on the Crofer22APU substrate. Flash sintering was found to be a promising and time efficient sintering technique to overcome some of the issues related to low coating density and oxide scale formation in solid oxide electrolysis cell conditions.

Nanomaterial Biointerfacing via Mitochondrial Membrane Coating for Targeted Detoxification and Molecular Detection.

Natural cell membranes derived from various cell sources have been successfully utilized to coat nanomaterials for functionalization. However, intracellular membranes from the organelles of eukaryotes remain unexplored. Herein, we choose mitochondrion as a representative cell organelle and coat outer mitochondrial membrane (OMM) from mouse livers onto nanoparticles and field-effect transistors (FETs) through a membrane vesicle-substrate fusion process. Polymeric nanoparticles coated with OMM (OMM-NPs) can bind with ABT-263, a B-cell lymphoma protein 2 (Bcl-2) inhibitor that targets the OMM. As a result, OMM-NPs effectively protect the cells from ABT-263 induced cell death and apoptosis in vitro and attenuated ABT-263-induced thrombocytopenia in vivo. Meanwhile, FET sensors coated with OMM (OMM-FETs) can detect and distinguish anti-Bcl-2 antibody and small molecule agonists. Overall, these results show that OMM can be coated onto the surfaces of both nanoparticles and functional devices, suggesting that intracellular membranes can be used as coating materials for novel biointerfacing.

In situ Grazing Incidence Small Angle X-ray Scattering on Roll-To-Roll Coating of Organic Solar Cells with Laboratory X-ray Instrumentation.

We present an in-house, in situ Grazing Incidence Small Angle X-ray Scattering (GISAXS) experiment, developed to probe the drying kinetics of roll-to-roll slot-die coating of the active layer in organic photovoltaics (OPVs), during deposition. For this demonstration, the focus is on the combination of P3HT:O-IDTBR and P3HT:EH-IDTBR, which have different drying kinetics and device performance, despite their chemical structure only varying slightly by the sidechain of the small molecule acceptor. This article provides a step-by-step guide to perform an in situ GISAXS experiment and demonstrates how to analyze and interpret the results. Usually, performing this type of in situ X-ray experiments to investigate the drying kinetics of the active layer in OPVs relies on access to synchrotrons. However, by using and further developing the method described in this paper, it is possible to perform experiments with a coarse temporal and spatial resolution, on a day-to-day basis to gain fundamental insight in the morphology of drying inks.

In situ Grazing Incidence Small Angle X-ray Scattering on Roll-To-Roll Coating of Organic Solar Cells with Laboratory X-ray Instrumentation

In situ Grazing Incidence Small Angle X-ray Scattering on Roll-To-Roll Coating of Organic Solar Cells with Laboratory X-ray Instrumentation

Surface‐Triggered In Situ Gelation for Tunable Conformal Hydrogel Coating of Therapeutic Cells and Biomedical Devices

AbstractHydrogel coatings have been proposed as a promising strategy to improve the biocompatibility of therapeutic cells and biomedical devices. However, developed coating methods are only applicable for simple geometries, typical sizes, and limited substrates. In addition, its applications in therapeutic cell encapsulation are hampered by inadequate construction of the hydrogel capsules such as off‐center encapsulation, immense volume, and lack of control over the thickness of capsules. Here, a method called surface‐triggered in situ gelation (STIG) for universal hydrogel coating of multiscale objects ranging from single cells to mini‐organs to biomedical devices with arbitrary shapes and heterogeneous components is reported. By covering cells or devices with calcium carbonate particles, progressive propagation of alginate hydrogel from their surface under the stimulation of GDL is achieved. The thickness of the hydrogel layers can be easily controlled from several micrometers to hundreds of micrometers by adjusting the gelation time and the release rate of calcium ions. Importantly, STIG facilitates accurate, complete, and individual cell encapsulation, which potentially overcomes the pitfalls of conventional strategies. It is further proven that the low‐cost and facile method can potentially lead to advances in different fields by rendering precisely controlled microscale alginate layers on a wide variety of biomedical substrates.

Glycocalyx as Possible Limiting Factor in COVID-19.

Glycocalyx as Possible Limiting Factor in COVID-19.