Artigos de revistas sobre o tema "Interactions cellules/surfaces"
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Le, Huong, Hoang-Nghi Mai-Thi, Xuan Le, Ngoc Quyen Tran, Cam Tu Tran e Khon Huynh. "The concentration-independence cellular effects of fibronectin adsorbed on material surfaces with different hydrophobicities". Vietnam Journal of Biotechnology 20, n.º 3 (30 de setembro de 2022): 435–44. http://dx.doi.org/10.15625/1811-4989/16585.
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In tissue engineering, coating biomaterial’s surface with extracellular matrix (ECM) proteins can promote many biological activities, including cellular responses, wound healing, and rejection reduction. Several interactions occur upon binding proteins onto the surfaces, leading to changes in the protein structural conformation, directly affecting the cell-host interactions. Therefore, this study investigates the impacts of surfaces’ wettability on protein conformation. In order to get the insights, organosilicate (OGS) was utilized to modify the tissue culture plate, resulting in surfaces with different wettability, followed by fibronectin (FN) immobilization. Then, the surfaces were used to study the fibrinogen interaction, cell attachment, and spreading. The results showed that OGS-modified surfaces produced four different wettability, ranging from super-hydrophilic (OGS150), hydrophilic (OGS100), hydrophobic (OGS60), to super-hydrophobic (OGS5). Each surface possessed particular nature, resulting in the variation of FN molecules' structural change. The amount of FN adsorbed on the OGS-coated surfaces was shown not to be perfectly proportional to the results of fibrinogen interaction, cell attachment, and spreading. The super-hydrophobic surfaces (OGS5) were highest in the amount of immobilized FN and the efficiency in subsequent experiments among the OGS-coated surfaces group. Notably, the hydrophobic surface adsorbed the lowest amount of FN but achieved remarkable results in the following experiments. Thus, this study holds a promising potential in producing biocompatible materials in tissue engineering.
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Noh, In Sup, e Elazer R. Edelman. "Smooth Muscle Cell Ingrowth of a Surface-Modified ePTFE Vascular Graft". Key Engineering Materials 288-289 (junho de 2005): 367–72. http://dx.doi.org/10.4028/www.scientific.net/kem.288-289.367.
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A variety of attempts have been made to improve small diameter expanded polytetrafluoroethylene (ePTFE) vascular grafts through cellular and tissue engineering. Some of these techniques have made their way into clinical trials. Coating of endothelial cells via surface modifications has increased graft patency in some hands but lack of firm adhesion of the seeded cells on the graft surface can lead to graft failures. We increased cell-graft and graft-tissue interactions by inducing smooth muscle cell growth into the pores of the graft wall through chemical modification of superficial surfaces, including those of the transmural pores. In contrast to non-modified surfaces seeded cells adhered on and proliferated into the modified pores and internodal surfaces. Cellular growth into these critical pores spaces seemed to arise from surface modification including defluorination and oxygenation incorporation leading to changes in chemical composition, surface tension, cell-surface interaction and modified surface fibril aggregation.
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Matsuoka, Satoshi, Hideaki Yukawa, Masayuki Inui e Roy H. Doi. "Synergistic Interaction of Clostridium cellulovorans Cellulosomal Cellulases and HbpA". Journal of Bacteriology 189, n.º 20 (10 de agosto de 2007): 7190–94. http://dx.doi.org/10.1128/jb.00842-07.
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ABSTRACT Clostridium cellulovorans, an anaerobic bacterium, produces a small nonenzymatic protein called HbpA, which has a surface layer homology domain and a type I cohesin domain similar to those found in the cellulosomal scaffolding protein CbpA. In this study, we demonstrated that HbpA could bind to cell wall fragments from C. cellulovorans and insoluble polysaccharides and form a complex with cellulosomal cellulases endoglucanase B (EngB) and endoglucanase L (EngL). Synergistic degradative action of the cellulosomal cellulase and HbpA complexes was demonstrated on acid-swollen cellulose, Avicel, and corn fiber. We propose that HbpA functions to bind dockerin-containing cellulosomal enzymes to the cell surface and complements the activity of cellulosomes.
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Vilaró, Pilar, Carina Sampl, Gundula Teichert, Werner Schlemmer, Mathias Hobisch, Michael Weissl, Luis Panizzolo, Fernando Ferreira e Stefan Spirk. "Interactions and Dissociation Constants of Galactomannan Rendered Cellulose Films with Concavalin A by SPR Spectroscopy". Polymers 12, n.º 12 (18 de dezembro de 2020): 3040. http://dx.doi.org/10.3390/polym12123040.
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Interactions of biomolecules at interfaces are important for a variety of physiological processes. Among these, interactions of lectins with monosaccharides have been investigated extensively in the past, while polysaccharide-lectin interactions have scarcely been investigated. Here, we explore the adsorption of galactomannans (GM) extracted from Prosopis affinis on cellulose thin films determined by a combination of multi-parameter surface plasmon resonance spectroscopy (MP-SPR) and atomic force microscopy (AFM). The galactomannan adsorbs spontaneously on the cellulose surfaces forming monolayer type coverage (0.60 ± 0.20 mg·m−2). The interaction of a lectin, Concavalin A (ConA), with these GM rendered cellulose surfaces using MP-SPR has been investigated and the dissociation constant KD (2.1 ± 0.8 × 10−8 M) was determined in a range from 3.4 to 27.3 nM. The experiments revealed that the galactose side chains as well as the mannose reducing end of the GM are weakly interacting with the active sites of the lectins, whereas these interactions are potentially amplified by hydrophobic effects between the non-ionic GM and the lectins, thereby leading to an irreversible adsorption.
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Munro, Thomas, Catherine M. Miller, Elsa Antunes e Dileep Sharma. "Interactions of Osteoprogenitor Cells with a Novel Zirconia Implant Surface". Journal of Functional Biomaterials 11, n.º 3 (16 de julho de 2020): 50. http://dx.doi.org/10.3390/jfb11030050.
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Background: This study compared the in vitro response of a mouse pre-osteoblast cell line on a novel sandblasted zirconia surface with that of titanium. Material and Methods: The MC3T3-E1 subclone 4 osteoblast precursor cell line was cultured on either sandblasted titanium (SBCpTi) or sandblasted zirconia (SBY-TZP). The surface topography was analysed by three-dimensional laser microscopy and scanning electron microscope. The wettability of the discs was also assessed. The cellular response was quantified by assessing the morphology (day 1), proliferation (day 1, 3, 5, 7, 9), viability (day 1, 9), and migration (0, 6, 24 h) assays. Results: The sandblasting surface treatment in both titanium and zirconia increased the surface roughness by rendering a defined surface topography with titanium showing more apparent nano-topography. The wettability of the two surfaces showed no significant difference. The zirconia surface resulted in improved cellular spreading and a significantly increased rate of migration compared to titanium. However, the cellular proliferation and viability noted in our experiments were not significantly different on the zirconia and titanium surfaces. Conclusions: The novel, roughened zirconia surface elicited cellular responses comparable to, or exceeding that, of titanium. Therefore, this novel zirconia surface may be an acceptable substitute for titanium as a dental implant material.
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Meyle, J., H. Wolburg e A. F. Von Recum. "Surface Micromorphology and Cellular Interactions". Journal of Biomaterials Applications 7, n.º 4 (abril de 1993): 362–74. http://dx.doi.org/10.1177/088532829300700404.
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Kunrath, Marcel F., André Correia, Eduardo R. Teixeira, Roberto Hubler e Christer Dahlin. "Superhydrophilic Nanotextured Surfaces for Dental Implants: Influence of Early Saliva Contamination and Wet Storage". Nanomaterials 12, n.º 15 (28 de julho de 2022): 2603. http://dx.doi.org/10.3390/nano12152603.
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Hydrophilic and nanotextured surfaces for dental implants have been reported as relevant properties for early osseointegration. However, these surface characteristics are quite sensitive to oral interactions. Therefore, this pilot study aimed to investigate the superficial alterations caused on hydrophilic nanotubular surfaces after early human saliva interaction. Titanium disks were treated using an anodization protocol followed by reactive plasma application in order to achieve nanotopography and hydrophilicity, additionally; surfaces were stored in normal atmospheric oxygen or wet conditioning. Following, samples were interacted with saliva for 10 min and analyzed regarding physical–chemical properties and cellular viability. Saliva interaction did not show any significant influence on morphological characteristics, roughness measurements and chemical composition; however, hydrophilicity was statistically altered compromising this feature when the samples were stored in common air. Cellular viability tested with pre-osteoblasts cell line (MC3T3-E1) reduced significantly at 48 h on the samples without wet storage after saliva contamination. The applied wet-storage methodology appears to be effective in maintaining properties such as hydrophilicity during saliva interaction. In conclusion, saliva contamination might impair important properties of hydrophilic nanotubular surfaces when not stored in wet conditions, suggesting the need of saliva-controlled sites for oral application of hydrophilic surfaces and/or the use of modified-package methods associated with their wet storage.
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Bucior, Iwona, Simon Scheuring, Andreas Engel e Max M. Burger. "Carbohydrate–carbohydrate interaction provides adhesion force and specificity for cellular recognition". Journal of Cell Biology 165, n.º 4 (17 de maio de 2004): 529–37. http://dx.doi.org/10.1083/jcb.200309005.
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The adhesion force and specificity in the first experimental evidence for cell–cell recognition in the animal kingdom were assigned to marine sponge cell surface proteoglycans. However, the question whether the specificity resided in a protein or carbohydrate moiety could not yet be resolved. Here, the strength and species specificity of cell–cell recognition could be assigned to a direct carbohydrate–carbohydrate interaction. Atomic force microscopy measurements revealed equally strong adhesion forces between glycan molecules (190–310 piconewtons) as between proteins in antibody–antigen interactions (244 piconewtons). Quantitative measurements of adhesion forces between glycans from identical species versus glycans from different species confirmed the species specificity of the interaction. Glycan-coated beads aggregated according to their species of origin, i.e., the same way as live sponge cells did. Live cells also demonstrated species selective binding to glycans coated on surfaces. These findings confirm for the first time the existence of relatively strong and species-specific recognition between surface glycans, a process that may have significant implications in cellular recognition.
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Banci, Lucia, Ivano Bertini, Vito Calderone, Nunzia Della-Malva, Isabella C. Felli, Sara Neri, Anna Pavelkova e Antonio Rosato. "Copper(I)-mediated protein–protein interactions result from suboptimal interaction surfaces". Biochemical Journal 422, n.º 1 (29 de julho de 2009): 37–42. http://dx.doi.org/10.1042/bj20090422.
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The homoeostasis of metal ions in cells is the result of the contribution of several cellular pathways that involve transient, often weak, protein–protein interactions. Metal transfer typically implies the formation of adducts where the metal itself acts as a bridge between proteins, by co-ordinating residues of both interacting partners. In the present study we address the interaction between the human copper(I)-chaperone HAH1 (human ATX1 homologue) and a metal-binding domain in one of its partners, namely the P-type copper-transporting ATPase, ATP7A (ATPase, Cu+ transporting, α polypeptide). The adduct was structurally characterized in solution, in the presence of copper(I), and through X-ray crystallography, upon replacing copper(I) with cadmium(II). Further insight was obtained through molecular modelling techniques and site-directed mutagenesis. It was found that the interaction involves a relatively small interface (less than 1000 Å2, 1 Å=0.1 nm) with a low fraction of non-polar atoms. These observations provide a possible explanation for the low affinity of the two apoproteins. It appears that electrostatics is important in selecting which domain of the ATPase is able to form detectable amounts of the metal-mediated adduct with HAH1.
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De Wever, Pieter, Rodrigo de Oliveira-Silva, João Marreiros, Rob Ameloot, Dimitrios Sakellariou e Pedro Fardim. "Topochemical Engineering of Cellulose—Carboxymethyl Cellulose Beads: A Low-Field NMR Relaxometry Study". Molecules 26, n.º 1 (22 de dezembro de 2020): 14. http://dx.doi.org/10.3390/molecules26010014.
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The demand for more ecological, highly engineered hydrogel beads is driven by a multitude of applications such as enzyme immobilization, tissue engineering and superabsorbent materials. Despite great interest in hydrogel fabrication and utilization, the interaction of hydrogels with water is not fully understood. In this work, NMR relaxometry experiments were performed to study bead–water interactions, by probing the changes in bead morphology and surface energy resulting from the incorporation of carboxymethyl cellulose (CMC) into a cellulose matrix. The results show that CMC improves the swelling capacity of the beads, from 1.99 to 17.49, for pure cellulose beads and beads prepared with 30% CMC, respectively. Changes in water mobility and interaction energy were evaluated by NMR relaxometry. Our findings indicate a 2-fold effect arising from the CMC incorporation: bead/water interactions were enhanced by the addition of CMC, with minor additions having a greater effect on the surface energy parameter. At the same time, bead swelling was recorded, leading to a reduction in surface-bound water, enhancing water mobility inside the hydrogels. These findings suggest that topochemical engineering by adjusting the carboxymethyl cellulose content allows the tuning of water mobility and porosity in hybrid beads and potentially opens up new areas of application for this biomaterial.
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Yui, Nobuhiko. "Supramolecular Surfaces Modulating Cellular Response". Advances in Science and Technology 76 (outubro de 2010): 10–15. http://dx.doi.org/10.4028/www.scientific.net/ast.76.10.
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Polyrotaxane-immobilized surfaces were prepared as a platform of dynamic surfaces, which can prevent from non-specific interaction with plasma proteins and platelet, and then modulate cellular functions via specific interaction with receptor protein-ligand binding through movable polyrotaxane backbone. The immobilization of the polyrotaxane was carried out via two-step protocol, in which the polyrotaxane with tetraethyleneglycol dodecanethiol (TEGDT) anchoring group at both terminals was fixed onto Au substrate via Au-S bond, followed by the fixation of TEGDT molecule onto the Au substrate to complete the loop formation of polyrotaxane on the Au substrate with the help of self-assembled monolayer formation of TEGDT. Their surface properties were characterized by means dynamic contact angle measurements, and preliminary studies as biomaterials were performed in terms of plasma protein adsorption onto their surfaces.
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Yasuda, Takeshi, Tsumuko Okuno, Kaori Tsuji e Hirotsugu Yasuda. "Surface-Configuration Change of CF4Plasma Treated Cellulose and Cellulose Acetate by Interaction of Water with Surfaces". Langmuir 12, n.º 5 (janeiro de 1996): 1391–94. http://dx.doi.org/10.1021/la9501546.
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Kobayashi, Jun, Masanori Nishi, Yoshikatsu Akiyama, Masayuki Yamato, Hirofumi Yajima e Teruo Okano. "Selective Cell Adhesion and Detachment on Antibody-Immobilized Thermoresponsive Surfaces by Temperature Changes". Journal of Robotics and Mechatronics 25, n.º 4 (20 de agosto de 2013): 637–43. http://dx.doi.org/10.20965/jrm.2013.p0637.
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Anti-CD90 antibody-immobilized thermoresponsive (AIT) surfaces were prepared for obtaining temperature-triggered switching of the selective adhesion and detachment of CD90-expressed cells. Thymic carcinoma cells (Ty-82) expressing CD90 molecules on the cellular surface were unable to adhere to isotype AIT surfaces and aggregated. In contrast, Ty-82 cells selectively adhered to anti-CD90 AIT surfaces at 37°C. These results indicate that Ty-82 cells adhered to CD90 antibody-immobilized surfaces through affinity interaction, not through nonspecific interactions when grafted thermoresponsive polymer chains shrunk at 37°C. Adhered cells were detached from surfaces by lowering temperature to 20°C with pipetting. Although affinity interaction between cells and immobilized antibodies was decreased by the dynamic swelling of grafted thermoresponsive polymer chains by lowering temperature to 20°C, the application of additional force such as pipetting was required to completely detach adhered cells. Through temperature-induced changes in affinity interaction, the condensation of CD90-positive Ty-82 cells was carried out by using anti-CD90 AIT surfaces. AIT surfaces for regulating selective cell adhesion and detachment were then successfully prepared. A novel bioassembler technology using AIT surfaces could thus be useful for temperature-dependent selective cell adhesion/detachment such as cell separation.
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Hazan, Roshasnorlyza, Srimala Sreekantan, Adilah Abdul Khalil, Ira Maya Sophia Nordin e Ishak Mat. "TiO2 Foam: Characterization and Cell Adhesion". Advanced Materials Research 264-265 (junho de 2011): 1506–13. http://dx.doi.org/10.4028/www.scientific.net/amr.264-265.1506.
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In recent years, it has been proposed that the new era of implants design should be focused on the use of the new generation of biocompatible materials or reengineers the currently available materials. The objective of this research was to study cell-metal interactions using highly porous TiO2 foam. To obtain the porous TiO2 foam, polymeric foam replication methods might be one of the most effective methods. Surface chemical composition, morphology and phase are investigated by field emission scanning electron microscope (FESEM) and X-Ray Diffraction (XRD). In vitro cellular response of cells has been studied on TiO2 foam. In the investigations of the cellular responses of cells, two aspects were considered: the number of growing cells and their morphological features. It was clear that rough surface morphology was important factor for better cell-metal interaction. Surface topography can affect the cell migratory significantly and adhesion behavior on implant surfaces.
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Carambassis, Archie, e Mark W. Rutland. "Interactions of Cellulose Surfaces: Effect of Electrolyte". Langmuir 15, n.º 17 (agosto de 1999): 5584–90. http://dx.doi.org/10.1021/la9815852.
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Bachhuka, Akash. "(Invited) nanoengineered Surfaces for Modulating Cell-Surface Interaction and Sensing Applications". ECS Meeting Abstracts MA2023-01, n.º 34 (28 de agosto de 2023): 1889. http://dx.doi.org/10.1149/ma2023-01341889mtgabs.
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The greatest challenge in the field of biomaterials is the understanding and prediction of long-term biological responses in patients receiving implantable materials. Reconstructing and detailing these mechanisms may allow for more targeted approaches and highlights how immune processes are amenable to manipulation by synthetic biomaterials. Surface nanotopography and chemistry are critical factors in integrating implanted devices into tissues and in the satisfactory resolution of the wound healing process. However, how the interplay between surface chemistry and nanotopography may influence inflammatory and wound-healing pathways remains unanswered. To address this gap, 2D and 3D surfaces with nanotopography of controlled height (16, 38, and 68 nm) and lateral spacing with uniform outermost surface chemistry tailored with plasma polymerized amines (NH2), carboxyl (COOH-) and hydrocarbon (CH3-) functionalities were fabricated. These surfaces were employed to study cellular responses responsible for implant encapsulation, wound healing, and tissue regeneration. The data shows that the right combination of chemistry and nanotopography can modulate cellular adhesion, proliferation, self-differentiation, collagen deposition, and the expression of anti and pro-inflammatory signals. Furthermore, our surface engineering expertise was utilized to fabricate metal ion sensors and biosensors based on nanoporous anodic alumina (NAA) and gold nanoclusters (AuNCs). We anticipate that future explorations in this field of research will facilitate the rational design of biomedical implants and devices with physicochemical surface characteristics tailored at the nanoscale that will enhance utility and function and improve clinical outcomes.
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Sulman, Aleksanrina, Olga Grebennikova, Boris Tikhonov, Vladimir Molchanov e Valentina Matveeva. "Immobilized cellulase: Interactions between cellulase and nanostructured supports". BIO Web of Conferences 64 (2023): 01016. http://dx.doi.org/10.1051/bioconf/20236401016.
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In this review, we will analyze the main aspects of immobilization of cellulase - an enzyme for processing cellulosic biomass waste - on nanostructured supports. Such substrates provide a large surface area, increased enzymatic load and a favorable environment for increasing the efficiency of cellulase and its stability, which leads to the creation of nanobiocatalysts for the production of biofuels and chemicals with added value. Here we will discuss nanostructured supports, methods of cellulase immobilization, the interaction between the enzyme and the support, as well as factors affecting the activity of the enzyme to achieve maximum conversion of cellulose biowaste into fermentable sugars.
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Gozan, Misri, Andre Fahriz Harahap, Chandra Paska Bakti e Siswa Setyahadi. "Optimization of cellulase production by bacillus sp. BPPT CC RK2 with pH and temperature variation using response surface methodology". E3S Web of Conferences 67 (2018): 02051. http://dx.doi.org/10.1051/e3sconf/20186702051.
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Indonesia has abundant ethanol biomass feedstocks. However the second-generation ethanol production process is still hampered by the unavailability of cellulase enzyme in the process of decomposition of lignocellulose into saccharides that can be processed into ethanol through fermentation. Cellulase is known as exozyme produced by Bacillus sp. in submerged fermentation. In this study, cellulase production by Bacillus sp. CC BPPT RK2 on natural and abundant agricultural waste substrates (rice bran and coconut water) was evaluated by investigating the optimum conditions for cellulase production in a 50 ml laboratory scale. Preliminary test using Luria Bentani (LB) medium with additional CMC (1%) were done to select optimum range of pH and Temperature. The preliminary tests results were then followed by optimization of pH and temperature, which were carried out using response surface methodology (RSM). RSM optimization model showed optimum values 6.23 for pH and 40.04 °C, with 14 terms (each with 1 degree of freedom), 4 linear effects, 6 interaction effects and 4 quadratic effects. These optimization by RSM results were slightly different compared to preliminary test, showing the effect of interactions between parameters. The characteristics of interaction among variables tested against the cellulase activity are reported in this study including: positive effects on cellulase activity of the resulting responses; negative interactions affecting the response of cellulase activity; synergistic interaction; and antagonistic interactions between each other.
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Stahelin, Robert V. "Surface plasmon resonance: a useful technique for cell biologists to characterize biomolecular interactions". Molecular Biology of the Cell 24, n.º 7 (abril de 2013): 883–86. http://dx.doi.org/10.1091/mbc.e12-10-0713.
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Surface plasmon resonance (SPR) is a powerful technique for monitoring the affinity and selectivity of biomolecular interactions. SPR allows for analysis of association and dissociation rate constants and modeling of biomolecular interaction kinetics, as well as for equilibrium binding analysis and ligand specificity studies. SPR has received much use and improved precision in classifying protein–protein interactions, as well as in studying small-molecule ligand binding to receptors; however, lipid–protein interactions have been underserved in this regard. With the field of lipids perhaps the next frontier in cellular research, SPR is a highly advantageous technique for cell biologists, as newly identified proteins that associate with cellular membranes can be screened rapidly and robustly for lipid specificity and membrane affinity. This technical perspective discusses the conditions needed to achieve success with lipid–protein interactions and highlights the unique lipid–protein interaction mechanisms that have been elucidated using SPR. It is intended to provide the reader a framework for quantitative and confident conclusions from SPR analysis of lipid–protein interactions.
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Suárez-Franco, José Luis, Manuel García-Hipólito, Miguel Ángel Surárez-Rosales, José Arturo Fernández-Pedrero, Octavio Álvarez-Fregoso, Julio Alberto Juárez-Islas e Marco Antonio Álvarez-Pérez. "Effects of Surface Morphology ofZnAl2O4Ceramic Materials on Osteoblastic Cells Responses". Journal of Nanomaterials 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/361249.
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Ceramic scaffolds are widely studied in the tissue engineering field due to their potential in medical applications as bone substitutes or as bone-filling materials. The purpose of this study was to investigate the effect of surface morphology of nanostructure thin films of ZnAl2O4prepared by spray pyrolysis and bulk pellets of polycrystalline ZnAl2O4prepared by chemical coprecipitation reaction on thein vitrocell adhesion, viability, and cell-material interactions of osteoblastic cells. Our result showed that cell attachment was significantly enhanced from 60 to 80% on the ZnAl2O4nanostructured material surface when compared with bulk ceramic surfaces. Moreover, our results showed that the balance of morphological properties of the thin film nanostructure ceramic improves cell-material interaction with enhanced spreading and filopodia with multiple cellular extensions on the surface of the ceramic and enhancing cell viability/proliferation in comparison with bulk ceramic surfaces used as control. Altogether, these results suggest that zinc aluminate nanostructured materials have a great potential to be used in dental implant and bone substitute applications.
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He, Yongning, Steffen Mueller, Paul R. Chipman, Carol M. Bator, Xiaozhong Peng, Valorie D. Bowman, Suchetana Mukhopadhyay, Eckard Wimmer, Richard J. Kuhn e Michael G. Rossmann. "Complexes of Poliovirus Serotypes with Their Common Cellular Receptor, CD155". Journal of Virology 77, n.º 8 (15 de abril de 2003): 4827–35. http://dx.doi.org/10.1128/jvi.77.8.4827-4835.2003.
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ABSTRACT Structures of all three poliovirus (PV) serotypes (PV1, PV2, and PV3) complexed with their cellular receptor, PV receptor (PVR or CD155), were determined by cryoelectron microscopy. Both glycosylated and fully deglycosylated CD155 exhibited similar binding sites and orientations in the viral canyon for all three PV serotypes, showing that all three serotypes use a common mechanism for cell entry. Difference maps between the glycosylated and deglycosylated CD155 complexes determined the sites of the carbohydrate moieties that, in turn, helped to verify the position of the receptor relative to the viral surface. The proximity of the CD155 carbohydrate site at Asn105 to the viral surface in the receptor-virus complex suggests that it might interfere with receptor docking, an observation consistent with the properties of mutant CD155. The footprints of CD155 on PV surfaces indicate that the south rim of the canyon dominates the virus-receptor interactions and may correspond to the initial CD155 binding state of the receptor-mediated viral uncoating. In contrast, the interaction of CD155 with the north rim of the canyon, especially the region immediately outside the viral hydrophobic pocket that normally binds a cellular “pocket factor,” may be critical for the release of the pocket factor, decreasing the virus stability and hence initiating uncoating. The large area of the CD155 footprint on the PV surface, in comparison with other picornavirus-receptor interactions, could be a potential limitation on the viability of PV escape mutants from antibody neutralization. Many of these are likely to have lost their ability to bind CD155, resulting in there being only three PV serotypes.
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Hedberg-Dirk, Elizabeth L., e Ulises A. Martinez. "Large-Scale Protein Arrays Generated with Interferometric Lithography for Spatial Control of Cell-Material Interactions". Journal of Nanomaterials 2010 (2010): 1–9. http://dx.doi.org/10.1155/2010/176750.
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Understanding cellular interactions with material surfaces at the micro- and nanometer scale is essential for the development of the next generation of biomaterials. Several techniques have been used to create micro- and nanopatterned surfaces as a means of studying cellular interactions with a surface. Herein, we report the novel use of interference lithography to create a large (4 ) array of 33 nm deep channels in a gold surface, to expose an antireflective coating on a silicon wafer at the bottom of the gold channels. The fabricated pores had a diameter of 140–350 nm separated by an average pitch of 304–750 nm, depending on the fabrication conditions. The gold surface was treated with 2-(2-(2-(11-mercaptoundecyloxy)ethoxy)ethoxy)ethanol to create protein-resistant areas. Fibronectin was selectively adsorbed onto the exposed antireflective coating creating nanometer-scale cell adhesive domains. A murine osteoblast cell line (MC3T3-E1) was seeded onto the surfaces and was shown to attach to the fibronectin domains and spread across the material surface.
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Masas, Daria S., Maria S. Ivanova, Gocha Sh Gogelashvili, Alexander S. Maslennikov, Yury B. Grunin e Tatiana Yu Grunina. "Analysis of water state adsorbed by cellulose fibers". Butlerov Communications 58, n.º 5 (31 de maio de 2019): 24–31. http://dx.doi.org/10.37952/roi-jbc-01/19-58-5-24.
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Modernized model of microfibril cellulose layered structure is proposed. This model considers presence of slit-shaped micropores in space between elementary fibrils and cellulose microfibrils. It’s discussed the nature of donor-acceptor hydrogen bonds formation: intra-, intermolecular, and interlayer bonds inherent in each glucopyranous cellulose link. It’s described the mechanism of water molecules specific adsorption interactions in a monolayer with active centers located on the hydrophilic surfaces of elementary fibrils. Dipole-dipole energy transition into energy of hydrogen bond is discussed during adsorption process between active centers of cellulose and water adsorptive molecules. Analysis of water molecules dipole-dipole interactions with surface hydroxyl groups of cellulose showed that at distance of 2.5-3 Å energy of this interaction transforms into energy of hydrogen bond. It is discussed the formation mechanism of water molecules donor-acceptor bonds with cellulose surface hydroxyl groups. Thermodynamic parameters characterizing adsorbate state the in these layers are determined by proton magnetic relaxation and sorption measurements. It’s established the possibility of determining adsorption net heat in bilayer considering Arrhenius nature of adsorbate thermal molecular motions correlation times. Increase in entropy of adsorbed water during adsorption process is revealed basis on Vant Hoff equation and certain adsorption equilibrium constant. The calculation established that distance between nearest active centers of cellulose is 6.5 Å. This leads to disunity of adsorbed water molecules and allows application of Langmuir and BET adsorption theory. Analysis of spin-lattice relaxation times dependence on cellulose moisture content made it possible to establish the cause of its crystallite wedging from adsorbed water molecules at adsorption initial stages. Decline of the spin-lattice relaxation unambiguously indicates the process of cellulose dispersion into its structural elements. It was established that during adsorption a part of the internal regions of crystallites passes to their surface with participation of cellulose hydroxyl groups. During desorption reverse process is observed.
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Niegelhell, Katrin, Thomas Ganner, Harald Plank, Evelyn Jantscher-Krenn e Stefan Spirk. "Lectins at Interfaces—An Atomic Force Microscopy and Multi-Parameter-Surface Plasmon Resonance Study". Materials 11, n.º 12 (22 de novembro de 2018): 2348. http://dx.doi.org/10.3390/ma11122348.
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Lectins are a diverse class of carbohydrate binding proteins with pivotal roles in cell communication and signaling in many (patho)physiologic processes in the human body, making them promising targets in drug development, for instance, in cancer or infectious diseases. Other applications of lectins employ their ability to recognize specific glycan epitopes in biosensors and glycan microarrays. While a lot of research has focused on lectin interaction with specific carbohydrates, the interaction potential of lectins with different types of surfaces has not been addressed extensively. Here, we screen the interaction of two specific plant lectins, Concanavalin A and Ulex Europaeus Agglutinin-I with different nanoscopic thin films. As a control, the same experiments were performed with Bovine Serum Albumin, a widely used marker for non-specific protein adsorption. In order to test the preferred type of interaction during adsorption, hydrophobic, hydrophilic and charged polymer films were explored, such as polystyrene, cellulose, N,-N,-N-trimethylchitosan chloride and gold, and characterized in terms of wettability, surface free energy, zeta potential and morphology. Atomic force microscopy images of surfaces after protein adsorption correlated very well with the observed mass of adsorbed protein. Surface plasmon resonance spectroscopy studies revealed low adsorbed amounts and slow kinetics for all of the investigated proteins for hydrophilic surfaces, making those resistant to non-specific interactions. As a consequence, they may serve as favorable supports for biosensors, since the use of blocking agents is not necessary.
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Österbeg, Monika, e Per M. Claesson. "Interactions between cellulose surfaces: effect of solution pH". Journal of Adhesion Science and Technology 14, n.º 5 (janeiro de 2000): 603–18. http://dx.doi.org/10.1163/156856100742771.
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Lydon, M. J., T. W. Minett e B. J. Tighe. "Cellular interactions with synthetic polymer surfaces in culture". Biomaterials 6, n.º 6 (novembro de 1985): 396–402. http://dx.doi.org/10.1016/0142-9612(85)90100-0.
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Oikonomou, Evdokia K., e Jean-François Berret. "Adsorption of Fragrance Capsules onto Cellulose Nano- and Micro-Cellulose Fibers in Presence of Guar Biopolymers". Coatings 13, n.º 11 (25 de outubro de 2023): 1831. http://dx.doi.org/10.3390/coatings13111831.
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Fabric softeners are formulated to enhance textile softness and impart a pleasant scent. One of the most efficient technologies for controlled fragrance delivery onto fabrics involves encapsulating scent molecules in polymer capsules. Here, we investigate the adsorption of anionic fragrance capsules on cotton fabrics with the goal of reducing the reliance on palm-oil-derived surfactants. First, we employ 200 nm cellulose nanocrystals (CNC) as a reliable model for cotton fibers. CNC enables us to explore interactions among various softener components, including surfactants, guar biopolymers, and fragrances, using physical chemistry techniques applied to bulk dispersions. The primary objective is to elucidate the role of surfactant vesicles, the primary ingredient in textile conditioners, in the association between fragrance capsules and cotton. Secondly, we examine the influence of biopolymers present in a newly developed environmentally friendly softener on this association. Our findings demonstrate that anionic fragrance capsules are deposited onto cotton microfibers in the presence of either cationic surfactants or guar biopolymers, driven by electrostatic interactions. Scanning electron microscopy confirms capsule adsorption on textile fibers when these cationic ingredients are present. Understanding the interaction mechanisms between fragrance capsules and cotton fabrics, as well as the roles played by other softener components, can facilitate the design of more efficient and sustainable formulations.
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Juárez-Maldonado, Antonio, Hortensia Ortega-Ortíz, América Berenice Morales-Díaz, Susana González-Morales, Álvaro Morelos-Moreno, Marcelino Cabrera-De la Fuente, Alberto Sandoval-Rangel, Gregorio Cadenas-Pliego e Adalberto Benavides-Mendoza. "Nanoparticles and Nanomaterials as Plant Biostimulants". International Journal of Molecular Sciences 20, n.º 1 (4 de janeiro de 2019): 162. http://dx.doi.org/10.3390/ijms20010162.
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Biostimulants are materials that when applied in small amounts are capable of promoting plant growth. Nanoparticles (NPs) and nanomaterials (NMs) can be considered as biostimulants since, in specific ranges of concentration, generally in small levels, they increase plant growth. Pristine NPs and NMs have a high density of surface charges capable of unspecific interactions with the surface charges of the cell walls and membranes of plant cells. In the same way, functionalized NPs and NMs, and the NPs and NMs with a corona formed after the exposition to natural fluids such as water, soil solution, or the interior of organisms, present a high density of surface charges that interact with specific charged groups in cell surfaces. The magnitude of the interaction will depend on the materials adhered to the corona, but high-density charges located in a small volume cause an intense interaction capable of disturbing the density of surface charges of cell walls and membranes. The electrostatic disturbance can have an impact on the electrical potentials of the outer and inner surfaces, as well as on the transmembrane electrical potential, modifying the activity of the integral proteins of the membranes. The extension of the cellular response can range from biostimulation to cell death and will depend on the concentration, size, and the characteristics of the corona.
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Braniste, Tudor, Ion Tiginyanu, Tibor Horvath, Simion Raevschi, Serghei Cebotari, Marco Lux, Axel Haverich e Andres Hilfiker. "Viability and proliferation of endothelial cells upon exposure to GaN nanoparticles". Beilstein Journal of Nanotechnology 7 (23 de setembro de 2016): 1330–37. http://dx.doi.org/10.3762/bjnano.7.124.
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Nanotechnology is a rapidly growing and promising field of interest in medicine; however, nanoparticle–cell interactions are not yet fully understood. The goal of this work was to examine the interaction between endothelial cells and gallium nitride (GaN) semiconductor nanoparticles. Cellular viability, adhesion, proliferation, and uptake of nanoparticles by endothelial cells were investigated. The effect of free GaN nanoparticles versus the effect of growing endothelial cells on GaN functionalized surfaces was examined. To functionalize surfaces with GaN, GaN nanoparticles were synthesized on a sacrificial layer of zinc oxide (ZnO) nanoparticles using hydride vapor phase epitaxy. The uptake of GaN nanoparticles by porcine endothelial cells was strongly dependent upon whether they were fixed to the substrate surface or free floating in the medium. The endothelial cells grown on surfaces functionalized with GaN nanoparticles demonstrated excellent adhesion and proliferation, suggesting good biocompatibility of the nanostructured GaN.
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Myllytie, Petri, Jani Salmi e Janne Laine. "The influence of pH on the adsorption and interaction of chitosan with cellulose". BioResources 4, n.º 4 (26 de outubro de 2009): 1647–62. http://dx.doi.org/10.15376/biores.4.4.1647-1662.
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The pH dependent adsorption behavior of chitosan onto a cellulose model surface was studied by quartz crystal microbalance with dissipation (QCM-D). The molecular level interactions between adsorbed chitosan layers were studied by atom force microscopy (AFM) colloidal probe force measurements in the liquid phase. Adsorption of chitosan increased with pH below the solubility limit of the polymer. The adsorption behavior could not be accounted for solely on the basis of electrostatic interactions; thus a specific interaction between the polymers existed. Swelling and viscoelastic properties of the adsorbed chitosan layer were strongly influenced by pH. At high pH, the layer deswelled and became more elastic due to insolubility of the chitosan. The colloidal probe force measurements showed a rise of electrosteric repulsion after adsorption of chitosan at pH 5. Above the solubility limit of the chitosan, at pH 7, the pull-off force and its range clearly increased compared to lower pH values, indicating that the wet adhesion between chitosan-coated cellulose surfaces increased. The presented results are discussed in relation to the ability of chitosan to improve the initial wet strength of paper.
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Custódio, Catarina A., e João F. Mano. "Cell Surface Engineering to Control Cellular Interactions". ChemNanoMat 2, n.º 5 (maio de 2016): 376–84. http://dx.doi.org/10.1002/cnma.201600047.
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Lucenius, Jessica, Juan José Valle-Delgado, Kirsti Parikka e Monika Österberg. "Understanding hemicellulose-cellulose interactions in cellulose nanofibril-based composites". Journal of Colloid and Interface Science 555 (novembro de 2019): 104–14. http://dx.doi.org/10.1016/j.jcis.2019.07.053.
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Salmi, Jani, Tiina Nypelö, Monika Österberg e Janne Laine. "Layer structures formed by silica nanoparticles and cellulose nanofibrils with cationic polyacrylamide (C-PAM) on cellulose surface and their influence on interactions". BioResources 4, n.º 2 (16 de março de 2009): 602–25. http://dx.doi.org/10.15376/biores.4.2.602-625.
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A quartz crystal microbalance with dissipation monitoring (QCM-D) was used to study the adsorption of the layer formed by silica nanoparticles (SNP) and cellulose nanofibrils (NFC) together with cationic polyacrylamide (C-PAM) on cellulose surface, accompanied by use of atomic force microscope (AFM) to study the interactions between cellulose surfaces. The purpose was to understand the multilayer build-up compared to complex structure adsorption. The layer thickness and consequently also the repulsion between surfaces increased with each addition step during layer formation in the SNP-C-PAM systems, whereas the second addition of C-PAM decreased the repulsion in the case of NFC-C-PAM multilayer formation. An exceptionally high repulsion between surfaces was observed when nanofibrillar cellulose was added. This together with the extremely high dissipation values recorded with QCM-D indicated that nanofibrillar cellulose formed a loose and thick layer containing a lot of water. The multilayer systems formed fully and uniformly covered the surfaces. Silica nanoparticles were able to penetrate inside the loose C-PAM structure due to their small size. In contrast, NFC formed individual layers between C-PAM layers. The complex of C-PAM and SNP formed only a partly covered surface, leading to long-ranged pull-off force. This might explain the good flocculation properties reported for polyelectrolyte-nanoparticle systems.
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Fang, Qingming, Joel Andrews, Nidhi Sharma, Anna Wilk, Jennifer Clark, Jana Slyskova, Christopher A. Koczor, Hannes Lans, Aishwarya Prakash e Robert W. Sobol. "Stability and sub-cellular localization of DNA polymerase β is regulated by interactions with NQO1 and XRCC1 in response to oxidative stress". Nucleic Acids Research 47, n.º 12 (26 de abril de 2019): 6269–86. http://dx.doi.org/10.1093/nar/gkz293.
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Abstract Protein–protein interactions regulate many essential enzymatic processes in the cell. Somatic mutations outside of an enzyme active site can therefore impact cellular function by disruption of critical protein–protein interactions. In our investigation of the cellular impact of the T304I cancer mutation of DNA Polymerase β (Polβ), we find that mutation of this surface threonine residue impacts critical Polβ protein–protein interactions. We show that proteasome-mediated degradation of Polβ is regulated by both ubiquitin-dependent and ubiquitin-independent processes via unique protein–protein interactions. The ubiquitin-independent proteasome pathway regulates the stability of Polβ in the cytosol via interaction between Polβ and NAD(P)H quinone dehydrogenase 1 (NQO1) in an NADH-dependent manner. Conversely, the interaction of Polβ with the scaffold protein X-ray repair cross complementing 1 (XRCC1) plays a role in the localization of Polβ to the nuclear compartment and regulates the stability of Polβ via a ubiquitin-dependent pathway. Further, we find that oxidative stress promotes the dissociation of the Polβ/NQO1 complex, enhancing the interaction of Polβ with XRCC1. Our results reveal that somatic mutations such as T304I in Polβ impact critical protein–protein interactions, altering the stability and sub-cellular localization of Polβ and providing mechanistic insight into how key protein–protein interactions regulate cellular responses to stress.
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Canullo, Luigi, Tullio Genova, Esperanza Gross Trujillo, Guillermo Pradies, Sara Petrillo, Maurizio Muzzi, Stefano Carossa e Federico Mussano. "Fibroblast Interaction with Different Abutment Surfaces: In Vitro Study". International Journal of Molecular Sciences 21, n.º 6 (11 de março de 2020): 1919. http://dx.doi.org/10.3390/ijms21061919.
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Background: Attaining an effective mucosal attachment to the transmucosal part of the implant could protect the peri-implant bone. Aim: To evaluate if chair side surface treatments (plasma of Argon and ultraviolet light) may affect fibroblast adhesion on different titanium surfaces designed for soft tissue healing. Methods: Grade 5 titanium discs with four different surface topographies were subdivided into 3 groups: argon-plasma; ultraviolet light, and no treatment. Cell morphology and adhesion tests were performed at 20 min, 24 h, and 72 h. Results: Qualitative observation of the surfaces performed at the SEM was in accordance with the anticipated features. Roughness values ranged from smooth (MAC Sa = 0.2) to very rough (XA Sa = 21). At 20 min, all the untreated surfaces presented hemispherical cells with reduced filopodia, while the cells on treated samples were more spread with broad lamellipodia. However, these differences in spreading behavior disappeared at 24 h and 72 h. Argon-plasma, but not UV, significantly increased the number of fibroblasts independently of the surface type but only at 20 min. Statistically, there was no surface in combination with a treatment that favored a greater cellular adhesion. Conclusions: Data showed potential biological benefits of treating implant abutment surfaces with the plasma of argon in relation to early-stage cell adhesion.
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Preissner, K. T. "Heparinoids and cellular interactions in the vascular system". Hämostaseologie 16, n.º 01 (janeiro de 1996): 28–34. http://dx.doi.org/10.1055/s-0038-1656635.
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SummaryHeparin and related polysaccharides have long been used for therapautic intervention in different disease states related to thromboembolic complications. The localization and functional availability of heparin-like components in the body is mostly confined to cell surfaces and extracellular matrix/basement membranes. Their strategic position particularly in the vascular system enables heparinoids linked to various core proteins (designated as heparan sulfate proteoglycans) to interact with a variety of heparin-binding proteins such as apolipoproteins, lipases, proteases and protease inhibitors, matrix proteins as well as surface receptors on other cells and microorganisms. The variety in gene expression of respective core proteins and differences in glycosaminoglycan side chains are relevant factors for the selectivity of these interactions. Heparinoid-associated core proteins serve as co-receptors for a number of metabolic properties of vascular cells as well as for the regulation of cellular processes, particular as they relate to cell growth and differentiation in angiogenesis. Moreover, heparan sulfate proteoglycans contribute to the process of lipoprotein retention in the vessel wall and the onset of atherosclerosis. Elucidation of molecular properties, functions and their role in vascular diseases can lead to valuable information for the design of heparinoid analogues to be used for pharmacological intervention.
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Guttmann, Robin, Johannes Hoja, Christoph Lechner, Reinhard J. Maurer e Alexander F. Sax. "Adhesion, forces and the stability of interfaces". Beilstein Journal of Organic Chemistry 15 (11 de janeiro de 2019): 106–29. http://dx.doi.org/10.3762/bjoc.15.12.
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Weak molecular interactions (WMI) are responsible for processes such as physisorption; they are essential for the structure and stability of interfaces, and for bulk properties of liquids and molecular crystals. The dispersion interaction is one of the four basic interactions types – electrostatics, induction, dispersion and exchange repulsion – of which all WMIs are composed. The fact that each class of basic interactions covers a wide range explains the large variety of WMIs. To some of them, special names are assigned, such as hydrogen bonding or hydrophobic interactions. In chemistry, these WMIs are frequently used as if they were basic interaction types. For a long time, dispersion was largely ignored in chemistry, attractive intermolecular interactions were nearly exclusively attributed to electrostatic interactions. We discuss the importance of dispersion interactions for the stabilization in systems that are traditionally explained in terms of the “special interactions” mentioned above. System stabilization can be explained by using interaction energies, or by attractive forces between the interacting subsystems; in the case of stabilizing WMIs, one frequently speaks of adhesion energies and adhesive forces. We show that the description of system stability using maximum adhesive forces and the description using adhesion energies are not equivalent. The systems discussed are polyaromatic molecules adsorbed to graphene and carbon nanotubes; dimers of alcohols and amines; cellulose crystals; and alcohols adsorbed onto cellulose surfaces.
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Kumari, Pallavi, Tali Sayas, Patricia Bucki, Sigal Brown-Miyara e Maya Kleiman. "Real-Time Visualization of Cellulase Activity by Microorganisms on Surface". International Journal of Molecular Sciences 21, n.º 18 (9 de setembro de 2020): 6593. http://dx.doi.org/10.3390/ijms21186593.
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A variety of methods to detect cellulase secretion by microorganisms has been developed over the years, none of which enables the real-time visualization of cellulase activity on a surface. This visualization is critical to study the interaction between soil-borne cellulase-secreting microorganisms and the surface of plant roots and specifically, the effect of surface features on this interaction. Here, we modified the known carboxymethyl cellulase (CMC) hydrolysis visualization method to enable the real-time tracking of cellulase activity of microorganisms on a surface. A surface was formed using pure CMC with acridine orange dye incorporated in it. The dye disassociated from the film when hydrolysis occurred, forming a halo surrounding the point of hydrolysis. This enabled real-time visualization, since the common need for post hydrolysis dyeing was negated. Using root-knot nematode (RKN) as a model organism that penetrates plant roots, we showed that it was possible to follow microorganism cellulase secretion on the surface. Furthermore, the addition of natural additives was also shown to be an option and resulted in an increased RKN response. This method will be implemented in the future, investigating different microorganisms on a root surface microstructure replica, which can open a new avenue of research in the field of plant root–microorganism interactions.
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Mudedla, Sathish Kumar, Maisa Vuorte, Elias Veijola, Kaisa Marjamaa, Anu Koivula, Markus B. Linder, Suvi Arola e Maria Sammalkorpi. "Effect of oxidation on cellulose and water structure: a molecular dynamics simulation study". Cellulose 28, n.º 7 (3 de março de 2021): 3917–33. http://dx.doi.org/10.1007/s10570-021-03751-8.
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AbstractEnzymatic cleavage of glycocidic bonds is an important, green and biocompatible means to refine lignocellulosic biomass. Here, the effect of the resulting oxidation point defects on the structural and water interactions of crystalline cellulose {100} surface are explored using classical molecular dynamics simulations. We show that even single oxidations reduce the connections within cellulose crystal significantly, mostly via local interactions between the chains along the surface plane but also via the oxidation defects changing the structure of the crystal in direction perpendicular to the surface. Hydrogen bonding on the surface plane of cellulose is analyzed to identify onset of desorption of glucose chains, and the desorption probed. To assess the actual soluble product profile and their fractions resulting from lytic polysaccharide monooxygenase (LPMO) enzyme oxidation on real cellulose crystal samples, we employ High-Performance Anion-Exchange Chromatography with Pulsed Amperometric-Detection (HPAEC-PAD) technique. The findings demonstrate the LPMO oxidation results in soluble glucose fragments ranging from 2 to 8 glucose units in length. Additionally, significantly more oxidized oligosaccharides were released in LPMO treatment of AaltoCell than Avicel, the two studied microcrystalline cellulose species. This is likely to result from the large reactive surface area preserved in AaltoCell due to manufacturing process. Furthermore, as can be expected, the oxidation defects at the surfaces lead to the surfaces binding a larger amount of water both via direct influence by the defect but also the defect induced protrusions and fluctuations of the glucose chain. We quantify the enhancement of water interactions of cellulose crystals due to the oxidation defects, even when no desorption takes place. The molecular simulations indicate that the effect is most pronounced for the C1-acid oxidation (carboxylic acid formation) but present also for the other defects resulting from oxidation. The findings bear significance in understanding the effects of enzymatic oxidation on cellulose nanocrystals, the difference between cellulose species, and cleavage of soluble products from the cellulosic material.
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Schwaminger, Sebastian P., Paula Fraga-García, Felix Selbach, Florian G. Hein, Eva C. Fuß, Rifki Surya, Hans-Christian Roth et al. "Bio-nano interactions: cellulase on iron oxide nanoparticle surfaces". Adsorption 23, n.º 2-3 (31 de dezembro de 2016): 281–92. http://dx.doi.org/10.1007/s10450-016-9849-y.
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Moon, Jooa, Guanghao Hu e Tomohiro Hayashi. "Application of Machine Learning in the Quantitative Analysis of the Surface Characteristics of Highly Abundant Cytoplasmic Proteins: Toward AI-Based Biomimetics". Biomimetics 9, n.º 3 (6 de março de 2024): 162. http://dx.doi.org/10.3390/biomimetics9030162.
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Proteins in the crowded environment of human cells have often been studied regarding nonspecific interactions, misfolding, and aggregation, which may cause cellular malfunction and disease. Specifically, proteins with high abundance are more susceptible to these issues due to the law of mass action. Therefore, the surfaces of highly abundant cytoplasmic (HAC) proteins directly exposed to the environment can exhibit specific physicochemical, structural, and geometrical characteristics that reduce nonspecific interactions and adapt to the environment. However, the quantitative relationships between the overall surface descriptors still need clarification. Here, we used machine learning to identify HAC proteins using hydrophobicity, charge, roughness, secondary structures, and B-factor from the protein surfaces and quantified the contribution of each descriptor. First, several supervised learning algorithms were compared to solve binary classification problems for the surfaces of HAC and extracellular proteins. Then, logistic regression was used for the feature importance analysis of descriptors considering model performance (80.2% accuracy and 87.6% AUC) and interpretability. The HAC proteins showed positive correlations with negatively and positively charged areas but negative correlations with hydrophobicity, the B-factor, the proportion of beta structures, roughness, and the proportion of disordered regions. Finally, the details of each descriptor could be explained concerning adaptative surface strategies of HAC proteins to regulate nonspecific interactions, protein folding, flexibility, stability, and adsorption. This study presented a novel approach using various surface descriptors to identify HAC proteins and provided quantitative design rules for the surfaces well-suited to human cellular crowded environments.
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Aguirre, Luis E., Alexandre de Oliveira, David Seč, Simon Čopar, Pedro L. Almeida, Miha Ravnik, Maria Helena Godinho e Slobodan Žumer. "Sensing surface morphology of biofibers by decorating spider silk and cellulosic filaments with nematic microdroplets". Proceedings of the National Academy of Sciences 113, n.º 5 (14 de janeiro de 2016): 1174–79. http://dx.doi.org/10.1073/pnas.1518739113.
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Probing the surface morphology of microthin fibers such as naturally occurring biofibers is essential for understanding their structural properties, biological function, and mechanical performance. The state-of-the-art methods for studying the surfaces of biofibers are atomic force microscopy imaging and scanning electron microscopy, which well characterize surface geometry of the fibers but provide little information on the local interaction potential of the fibers with the surrounding material. In contrast, complex nematic fluids respond very well to external fields and change their optical properties upon such stimuli. Here we demonstrate that liquid crystal droplets deposited on microthin biofibers—including spider silk and cellulosic fibers—reveal characteristics of the fibers’ surface, performing as simple but sensitive surface sensors. By combining experiments and numerical modeling, different types of fibers are identified through the fiber-to-nematic droplet interactions, including perpendicular and axial or helicoidal planar molecular alignment. Spider silks align nematic molecules parallel to fibers or perpendicular to them, whereas cellulose aligns the molecules unidirectionally or helicoidally along the fibers, indicating notably different surface interactions. The nematic droplets as sensors thus directly reveal chirality of cellulosic fibers. Different fiber entanglements can be identified by depositing droplets exactly at the fiber crossings. More generally, the presented method can be used as a simple but powerful approach for probing the surface properties of small-size bioobjects, opening a route to their precise characterization.
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Wen, Fei, Jie Sun e Huimin Zhao. "Yeast Surface Display of Trifunctional Minicellulosomes for Simultaneous Saccharification and Fermentation of Cellulose to Ethanol". Applied and Environmental Microbiology 76, n.º 4 (18 de dezembro de 2009): 1251–60. http://dx.doi.org/10.1128/aem.01687-09.
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ABSTRACT By combining cellulase production, cellulose hydrolysis, and sugar fermentation into a single step, consolidated bioprocessing (CBP) represents a promising technology for biofuel production. Here we report engineering of Saccharomyces cerevisiae strains displaying a series of uni-, bi-, and trifunctional minicellulosomes. These minicellulosomes consist of (i) a miniscaffoldin containing a cellulose-binding domain and three cohesin modules, which was tethered to the cell surface through the yeast a-agglutinin adhesion receptor, and (ii) up to three types of cellulases, an endoglucanase, a cellobiohydrolase, and a β-glucosidase, each bearing a C-terminal dockerin. Cell surface assembly of the minicellulosomes was dependent on expression of the miniscaffoldin, indicating that formation of the complex was dictated by the high-affinity interactions between cohesins and dockerins. Compared to the unifunctional and bifunctional minicellulosomes, the quaternary trifunctional complexes showed enhanced enzyme-enzyme synergy and enzyme proximity synergy. More importantly, surface display of the trifunctional minicellulosomes gave yeast cells the ability to simultaneously break down and ferment phosphoric acid-swollen cellulose to ethanol with a titer of ∼1.8 g/liter. To our knowledge, this is the first report of a recombinant yeast strain capable of producing cell-associated trifunctional minicellulosomes. The strain reported here represents a useful engineering platform for developing CBP-enabling microorganisms and elucidating principles of cellulosome construction and mode of action.
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Bimbo, Luis M., Mirkka Sarparanta, Ermei Mäkilä, Timo Laaksonen, Päivi Laaksonen, Jarno Salonen, Markus B. Linder, Jouni Hirvonen, Anu J. Airaksinen e Hélder A. Santos. "Cellular interactions of surface modified nanoporous silicon particles". Nanoscale 4, n.º 10 (2012): 3184. http://dx.doi.org/10.1039/c2nr30397c.
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Wang, Yi, Sok Ho Kim, Ramya Natarajan, Jason E. Heindl, Eric L. Bruger, Christopher M. Waters, Anthony J. Michael e Clay Fuqua. "Spermidine Inversely Influences Surface Interactions and Planktonic Growth in Agrobacterium tumefaciens". Journal of Bacteriology 198, n.º 19 (11 de julho de 2016): 2682–91. http://dx.doi.org/10.1128/jb.00265-16.
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ABSTRACTIn bacteria, the functions of polyamines, small linear polycations, are poorly defined, but these metabolites can influence biofilm formation in several systems. Transposon insertions in an ornithine decarboxylase (odc) gene inAgrobacterium tumefaciens, predicted to direct synthesis of the polyamine putrescine from ornithine, resulted in elevated cellulose. Null mutants forodcgrew somewhat slowly in a polyamine-free medium but exhibited increased biofilm formation that was dependent on cellulose production. Spermidine is an essential metabolite inA. tumefaciensand is synthesized from putrescine inA. tumefaciensvia the stepwise actions of carboxyspermidine dehydrogenase (CASDH) and carboxyspermidine decarboxylase (CASDC). Exogenous addition of either putrescine or spermidine to theodcmutant returned biofilm formation to wild-type levels. Low levels of exogenous spermidine restored growth to CASDH and CASDC mutants, facilitating weak biofilm formation, but this was dampened with increasing concentrations. Norspermidine rescued growth for theodc, CASDH, and CASDC mutants but did not significantly affect their biofilm phenotypes, whereas in the wild type, it stimulated biofilm formation and depressed spermidine levels. Theodcmutant produced elevated levels of cyclic diguanylate monophosphate (c-di-GMP), exogenous polyamines modulated these levels, and expression of a c-di-GMP phosphodiesterase reversed the enhanced biofilm formation. Prior work revealed accumulation of the precursors putrescine and carboxyspermidine in the CASDH and CASDC mutants, respectively, but unexpectedly, both mutants accumulated homospermidine; here, we show that this requires a homospermidine synthase (hss) homologue.IMPORTANCEPolyamines are small, positively charged metabolites that are nearly ubiquitous in cellular life. They are often essential in eukaryotes and more variably in bacteria. Polyamines have been reported to influence the surface-attached biofilm formation of several bacteria. InAgrobacterium tumefaciens, mutants with diminished levels of the polyamine spermidine are stimulated for biofilm formation, and exogenous provision of spermidine decreases biofilm formation. Spermidine is also essential forA. tumefaciensgrowth, but the related polyamine norspermidine exogenously rescues growth and does not diminish biofilm formation, revealing that the growth requirement and biofilm control are separable. Polyamine control of biofilm formation appears to function via effects on the cellular second messenger cyclic diguanylate monophosphate, regulating the transition from a free-living to a surface-attached lifestyle.
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Porter, Stace W., Qingping Xu e Ann H. West. "Ssk1p Response Regulator Binding Surface on Histidine- Containing Phosphotransfer Protein Ypd1p". Eukaryotic Cell 2, n.º 1 (fevereiro de 2003): 27–33. http://dx.doi.org/10.1128/ec.2.1.27-33.2003.
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ABSTRACT Ypd1p, a histidine-containing phosphotransfer protein, plays an important role in a branched His-Asp phosphorelay signal transduction pathway that regulates cellular responses to hyperosmotic stress in Saccharomyces cerevisiae. Ypd1p is required for phosphoryl group transfer from the membrane-bound Sln1p sensor histidine kinase to two downstream response regulator proteins, Ssk1p and Skn7p. To investigate the molecular basis for interaction of Ypd1p with these response regulator domains, we used an approach that coupled alanine-scanning mutagenesis of surface-exposed residues in Ypd1p with a yeast two-hybrid interaction screen. Mutated residues that adversely affected the interaction of Ypd1p with the C-terminal response regulator domain of Ssk1p were identified and found to cluster on or near the αA helix in Ypd1p. Our results, supported by analysis of a modeled complex, identify a binding site on Ypd1p for response regulators that is composed of a cluster of conserved hydrophobic residues surrounded by less conserved polar residues. We propose that molecular interactions involving Ypd1p are mediated primarily through hydrophobic contacts, whereas binding specificity and strength of interaction may be influenced by select polar side chain interactions.
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Kostylev, Maxim, e David Wilson. "A Distinct Model of Synergism between a Processive Endocellulase (TfCel9A) and an Exocellulase (TfCel48A) from Thermobifida fusca". Applied and Environmental Microbiology 80, n.º 1 (25 de outubro de 2013): 339–44. http://dx.doi.org/10.1128/aem.02706-13.
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ABSTRACTLignocellulosic biomass is digested in nature by the synergistic activities of enzymes with complementary properties, and understanding synergistic interactions will improve the efficiency of industrial biomass use for sustainable fuels and chemicals. Cel9A and Cel48A from a model bacterium,Thermobifida fusca(TfCel9A and TfCel48A, respectively), are two cellulases with different properties and have previously been shown to synergize well with each other. TfCel9A is a processive endocellulase with relatively high activity on crystalline cellulose. TfCel48A is a reducing end-directed exocellulase with very low activity on crystalline cellulose. Neither enzyme fits its respective role in the classical synergism model of enzymatic cellulose digestion. Using the results of time course, endpoint, and sequential addition activity assays, we propose a model of synergistic cooperation between the two cellulases. TfCel9A is most effective on fresh bacterial cellulose with a presumably uniform surface at the molecular level. Its processive activity likely erodes the surface and thus reduces its own activity. TfCel48A is able to hydrolyze the TfCel9A-modified substrate efficiently and replenish the uniform surface required by TfCel9A, creating a feedback mechanism. The model of synergistic interactions is comparable to an earlier proposed model forTrichoderma reeseiCel7A and Cel7B, but the roles of endo- and exocellulases are reversed, a finding which suggests that bacteria and fungi may have evolved different approaches to efficient biomass degradation.
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Sembajwe, Lawrence Fred, Abdul M. Ssekandi, Agnes Namaganda, Haruna Muwonge, Josephine N. Kasolo, Robert Kalyesubula, Annettee Nakimuli et al. "Glycocalyx–Sodium Interaction in Vascular Endothelium". Nutrients 15, n.º 13 (25 de junho de 2023): 2873. http://dx.doi.org/10.3390/nu15132873.
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The glycocalyx generally covers almost all cellular surfaces, where it participates in mediating cell-surface interactions with the extracellular matrix as well as with intracellular signaling molecules. The endothelial glycocalyx that covers the luminal surface mediates the interactions of endothelial cells with materials flowing in the circulating blood, including blood cells. Cardiovascular diseases (CVD) remain a major cause of morbidity and mortality around the world. The cardiovascular risk factors start by causing endothelial cell dysfunction associated with destruction or irregular maintenance of the glycocalyx, which may culminate into a full-blown cardiovascular disease. The endothelial glycocalyx plays a crucial role in shielding the cell from excessive exposure and absorption of excessive salt, which can potentially cause damage to the endothelial cells and underlying tissues of the blood vessels. So, in this mini review/commentary, we delineate and provide a concise summary of the various components of the glycocalyx, their interaction with salt, and subsequent involvement in the cardiovascular disease process. We also highlight the major components of the glycocalyx that could be used as disease biomarkers or as drug targets in the management of cardiovascular diseases.
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Christianson, Dawn R., Andrey S. Dobroff, Bettina Proneth, Amado J. Zurita, Ahmad Salameh, Eleonora Dondossola, Jun Makino et al. "Ligand-directed targeting of lymphatic vessels uncovers mechanistic insights in melanoma metastasis". Proceedings of the National Academy of Sciences 112, n.º 8 (6 de fevereiro de 2015): 2521–26. http://dx.doi.org/10.1073/pnas.1424994112.
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Metastasis is the most lethal step of cancer progression in patients with invasive melanoma. In most human cancers, including melanoma, tumor dissemination through the lymphatic vasculature provides a major route for tumor metastasis. Unfortunately, molecular mechanisms that facilitate interactions between melanoma cells and lymphatic vessels are unknown. Here, we developed an unbiased approach based on molecular mimicry to identify specific receptors that mediate lymphatic endothelial–melanoma cell interactions and metastasis. By screening combinatorial peptide libraries directly on afferent lymphatic vessels resected from melanoma patients during sentinel lymphatic mapping and lymph node biopsies, we identified a significant cohort of melanoma and lymphatic surface binding peptide sequences. The screening approach was designed so that lymphatic endothelium binding peptides mimic cell surface proteins on tumor cells. Therefore, relevant metastasis and lymphatic markers were biochemically identified, and a comprehensive molecular profile of the lymphatic endothelium during melanoma metastasis was generated. Our results identified expression of the phosphatase 2 regulatory subunit A, α-isoform (PPP2R1A) on the cell surfaces of both melanoma cells and lymphatic endothelial cells. Validation experiments showed that PPP2R1A is expressed on the cell surfaces of both melanoma and lymphatic endothelial cells in vitro as well as independent melanoma patient samples. More importantly, PPP2R1A-PPP2R1A homodimers occur at the cellular level to mediate cell–cell interactions at the lymphatic–tumor interface. Our results revealed that PPP2R1A is a new biomarker for melanoma metastasis and show, for the first time to our knowledge, an active interaction between the lymphatic vasculature and melanoma cells during tumor progression.
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Valero-Rello, Ana, Carlos Baeza-Delgado, Iván Andreu-Moreno e Rafael Sanjuán. "Cellular receptors for mammalian viruses". PLOS Pathogens 20, n.º 2 (20 de fevereiro de 2024): e1012021. http://dx.doi.org/10.1371/journal.ppat.1012021.
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The interaction of viral surface components with cellular receptors and other entry factors determines key features of viral infection such as host range, tropism and virulence. Despite intensive research, our understanding of these interactions remains limited. Here, we report a systematic analysis of published work on mammalian virus receptors and attachment factors. We build a dataset twice the size of those available to date and specify the role of each factor in virus entry. We identify cellular proteins that are preferentially used as virus receptors, which tend to be plasma membrane proteins with a high propensity to interact with other proteins. Using machine learning, we assign cell surface proteins a score that predicts their ability to function as virus receptors. Our results also reveal common patterns of receptor usage among viruses and suggest that enveloped viruses tend to use a broader repertoire of alternative receptors than non-enveloped viruses, a feature that might confer them with higher interspecies transmissibility.