scholarly journals Mechano-responsiveness of fibrillar adhesions on stiffness-gradient gels

2019 ◽  
Author(s):  
Nuria Barber-Pérez ◽  
Maria Georgiadou ◽  
Camilo Guzmán ◽  
Aleksi Isomursu ◽  
Hellyeh Hamidi ◽  
...  
Keyword(s):  
Focal Adhesions ◽  
Cost Effective ◽  
Dependent Manner ◽  
Mechanical Parameters ◽  
Force Microscopy ◽  
Physical Conditions ◽  
Atomic Force ◽  
Fibrillar Adhesion ◽  
Α5β1 Integrin ◽  
Fine Tune

AbstractFibrillar adhesions are important structural and adhesive components in fibroblasts that are critical for fibronectin fibrillogenesis. While nascent and focal adhesions are known to respond to mechanical cues, the mechanoresponsive nature of fibrillar adhesions remains unclear. Here, we used ratiometric analysis of paired adhesion components to determine an appropriate fibrillar adhesion marker. We found that active α5β1-integrin exhibits the most definitive fibrillar adhesion localisation compared to other proteins, such as tensin-1, reported to be in fibrillar adhesions. To elucidate the mechanoresponsiveness of fibrillar adhesions, we designed and fabricated thin polyacrylamide (PA) hydrogels, embedded with fluorescently labelled beads, with physiologically relevant stiffness gradients using a cost-effective and reproducible technique. We generated a correlation curve between bead density and hydrogel stiffness, thus allowing the use of bead density as a readout of stiffness, eliminating the need for specialised knowhow including atomic force microscopy (AFM). We find that stiffness promotes the growth of fibrillar adhesions in a tensin-dependent manner. Thus, the formation of these extracellular matrix-depositing structures is coupled to the mechanical parameters of the cell environment and may enable cells to fine-tune their matrix environment in response to alternating physical conditions.

scholarly journals Antibacterial Activity of Silver Nanoparticles Synthesized by Bark Extract of Syzygium cumini

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Ram Prasad ◽  
Vyshnava Satyanarayana Swamy
Keyword(s):  
Silver Nanoparticles ◽  
Antibacterial Activity ◽  
Cost Effective ◽  
Diffusion Method ◽  
Bark Extract ◽  
Force Microscopy ◽  
Atomic Force ◽  
Cost Effective Method ◽  
Uv Visible ◽  
Major Attention

The unique property of the silver nanoparticles having the antimicrobial activity drags the major attention towards the present nanotechnology. The environmentally nontoxic, ecofriendly, and cost-effective method that has been developed for the synthesis of silver nanoparticles using plant extracts creates the major research interest in the field of nanobiotechnology. The synthesized silver nanoparticles have been characterized by the UV-visible spectroscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM). Further, the antibacterial activity of silver nanoparticles was evaluated by well diffusion method, and it was found that the biogenic silver nanoparticles have antibacterial activity against Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 29213), Pseudomonas aeruginosa (ATCC 27853), Azotobacter chroococcum WR 9, and Bacillus licheniformis (MTCC 9555).

scholarly journals LIM-Nebulette Reinforces Podocyte Structural Integrity by Linking Actin and Vimentin Filaments

2020 ◽  
Vol 31 (10) ◽  
pp. 2372-2391 ◽  
Author(s):  
Xuhua Ge ◽  
Tao Zhang ◽  
Xiaoxia Yu ◽  
Alecia N. Muwonge ◽  
Nanditha Anandakrishnan ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Rho Gtpase ◽  
Focal Adhesions ◽  
Super Resolution ◽  
Actin Binding ◽  
Puromycin Aminonucleoside ◽  
Force Microscopy ◽  
Afm Indentation ◽  
Atomic Force ◽  
Key Aspects

BackgroundMaintenance of the intricate interdigitating morphology of podocytes is crucial for glomerular filtration. One of the key aspects of specialized podocyte morphology is the segregation and organization of distinct cytoskeletal filaments into different subcellular components, for which the exact mechanisms remain poorly understood.MethodsCells from rats, mice, and humans were used to describe the cytoskeletal configuration underlying podocyte structure. Screening the time-dependent proteomic changes in the rat puromycin aminonucleoside–induced nephropathy model correlated the actin-binding protein LIM-nebulette strongly with glomerular function. Single-cell RNA sequencing and immunogold labeling were used to determine Nebl expression specificity in podocytes. Automated high-content imaging, super-resolution microscopy, atomic force microscopy (AFM), live-cell imaging of calcium, and measurement of motility and adhesion dynamics characterized the physiologic role of LIM-nebulette in podocytes.ResultsNebl knockout mice have increased susceptibility to adriamycin-induced nephropathy and display morphologic, cytoskeletal, and focal adhesion abnormalities with altered calcium dynamics, motility, and Rho GTPase activity. LIM-nebulette expression is decreased in diabetic nephropathy and FSGS patients at both the transcript and protein level. In mice, rats, and humans, LIM-nebulette expression is localized to primary, secondary, and tertiary processes of podocytes, where it colocalizes with focal adhesions as well as with vimentin fibers. LIM-nebulette shRNA knockdown in immortalized human podocytes leads to dysregulation of vimentin filament organization and reduced cellular elasticity as measured by AFM indentation.ConclusionsLIM-nebulette is a multifunctional cytoskeletal protein that is critical in the maintenance of podocyte structural integrity through active reorganization of focal adhesions, the actin cytoskeleton, and intermediate filaments.

scholarly journals Towards an Understanding of Crystallization by Attachment

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 463
Author(s):  
Haihua Pan ◽  
Ruikang Tang
Keyword(s):  
Capillary Condensation ◽  
Force Measurements ◽  
Force Microscopy ◽  
Physical Conditions ◽  
Driving Mechanisms ◽  
Atomic Force ◽  
Wide Range ◽  
Dynamics Simulations ◽  
Hydration Layers

Crystallization via particle attachment was used in a unified model for both classical and non-classical crystallization pathways, which have been widely observed in biomimetic mineralization and geological fields. However, much remains unknown about the detailed processes and driving mechanisms for the attachment. Here, we take calcite crystal as a model mineral to investigate the detailed attachment process using in situ Atomic Force Microscopy (AFM) force measurements and molecular dynamics simulations. The results show that hydration layers hinder the attachment; however, in supersaturated solutions, ionic bridges are formed between crystal gaps as a result of capillary condensation, which might enhance the aggregation of calcite crystals. These findings provide a more detailed understanding of the crystal attachment, which is of vital importance for a better understanding of mineral formation under biological and geological environments with a wide range of chemical and physical conditions.

Atomic force microscopy measurement of leukocyte-endothelial interaction

2004 ◽  
Vol 286 (1) ◽  
pp. H359-H367 ◽  
Author(s):  
Xiaohui Zhang ◽  
Aileen Chen ◽  
Dina De Leon ◽  
Hong Li ◽  
Eisei Noiri ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Inflammatory Diseases ◽  
Leukocyte Adhesion ◽  
Umbilical Vein ◽  
Quantitative Measure ◽  
Dependent Manner ◽  
Average Force ◽  
Force Microscopy ◽  
Atomic Force ◽  
Umbilical Vein Endothelial Cells

Leukocyte adhesion to vascular endothelium is a key initiating step in the pathogenesis of many inflammatory diseases. In this study, we present real-time force measurements of the interaction between monocytic human promyelocytic leukemia cells (HL-60) cells and a monolayer of human umbilical vein endothelial cells (HUVECs) by using atomic force microscopy (AFM). The detachment of HL-60-HUVEC conjugates involved a series of rupture events with force transitions of 40–100 pN. The integrated force of these rupture events provided a quantitative measure of the adhesion strength on a whole cell level. The AFM measurements revealed that HL-60 adhesion is heightened in the borders formed by adjacent HUVECs. The average force and mechanical work required to detach a single HL-60 from the borders of a tumor necrosis factor-α-activated HUVEC layer were twice as high as those of the HUVEC bodies. HL-60 adhesion to the monolayer was significantly reduced by a monoclonal antibody against β1-integrins and partially inhibited by antibodies against selectins ICAM-1 and VCAM-1 but was not affected by anti-αVβ3. Interestingly, adhesion was also inhibited in a dose-dependent manner (IC50≈ 100 nM) by a cyclic arginine-glycine-aspartic acid (cRGD) peptide. This effect was mediated via interfering with the VLA-4-VCAM-1 binding. In parallel measurements, transmigration of HL-60 cells across a confluent HUVEC monolayer was inhibited by the cRGD peptide and by both anti-β1and anti-αVβ3antibodies. In conclusion, these data demonstrate the role played by β1-integrins in leukocyte-endothelial adhesion and transmigration and the role played by αVβ3in transmigration, thus underscoring the high efficacy of cRGD peptide in blocking both the adhesion and transmigration of monocytes.

scholarly journals Direct observation of dynamic force propagation between focal adhesions of cells on microposts by atomic force microscopy

2011 ◽  
Vol 99 (26) ◽  
pp. 263703 ◽  
Author(s):  
Akinori Okada ◽  
Yusuke Mizutani ◽  
Agus Subagyo ◽  
Hirotaka Hosoi ◽  
Motonori Nakamura ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Direct Observation ◽  
Focal Adhesions ◽  
Dynamic Force ◽  
Force Microscopy ◽  
Atomic Force ◽  
Force Propagation

Peel-off probe: a cost-effective probe for electrical atomic force microscopy

2000 ◽  
Author(s):  
Thomas Hantschel ◽  
Stefan Slesazeck ◽  
N. Duhayon ◽  
Mingwei Xu ◽  
Wilfried Vandervorst
Keyword(s):  
Atomic Force Microscopy ◽  
Cost Effective ◽  
Force Microscopy ◽  
Atomic Force

Ti-13Nb-13Zr Production for Implant Applications

2010 ◽  
Vol 660-661 ◽  
pp. 112-117
Author(s):  
Vinicius André Rodrigues Henriques ◽  
Cosme Roberto Moreira Silva ◽  
Carlos Alberto Alves Cairo ◽  
Eduardo T. Galvani
Keyword(s):  
Lamellar Structure ◽  
Cost Effective ◽  
Cold Isostatic Pressing ◽  
Grain Structure ◽  
Promising Candidate ◽  
Homogeneous Microstructure ◽  
Force Microscopy ◽  
Blended Elemental ◽  
Atomic Force ◽  
Complex Parts

Powder metallurgy (P/M) of titanium alloys may lead to the obtainment of components having weak-to-absent textures, uniform grain structure and higher homogeneity compared with conventional wrought products. The production of the Ti-13Nb-13Zr alloy by P/M starting from blended elemental (BE) powders is a cost-effective route considering its versatility and also for allowing the manufacture of complex parts. This alloy due its high biocompatibility and lower modulus of elasticity is a promising candidate for implants fabrication. Samples were produced by mixing of initial metallic powders followed by uniaxial and cold isostatic pressing with subsequent densification by sintering in order to identify the microstructural evolution. Sintered samples were characterized for phase composition, microstructure, microhardness and density. The surface topography of the samples was studied by means of atomic force microscopy (AFM). It was shown that the route is adequate to reach high densities with homogeneous microstructure. Representative AFM images allowed distinguishing a lamellar structure caused by the different phases that are present in the surface of the specimens.

scholarly journals p190RhoGAP is the convergence point of adhesion signals from α5β1 integrin and syndecan-4

2008 ◽  
Vol 181 (6) ◽  
pp. 1013-1026 ◽  
Author(s):  
Mark D. Bass ◽  
Mark R. Morgan ◽  
Kirsty A. Roach ◽  
Jeffrey Settleman ◽  
Andrew B. Goryachev ◽  
...  
Keyword(s):  
Adhesion Formation ◽  
Focal Adhesions ◽  
Dependent Manner ◽  
Rhoa Activity ◽  
Focal Adhesion Formation ◽  
Convergence Point ◽  
Individual Contributions ◽  
Guanosine Triphosphatase ◽  
Extracellular Matrix Receptors ◽  
Α5β1 Integrin

The fibronectin receptors α5β1 integrin and syndecan-4 cocluster in focal adhesions and coordinate cell migration by making individual contributions to the suppression of RhoA activity during matrix engagement. p190Rho–guanosine triphosphatase–activating protein (GAP) is known to inhibit RhoA during the early stages of cell spreading in an Src-dependent manner. This paper dissects the mechanisms of p190RhoGAP regulation and distinguishes the contributions of α5β1 integrin and syndecan-4. Matrix-induced tyrosine phosphorylation of p190RhoGAP is stimulated solely by engagement of α5β1 integrin and is independent of syndecan-4. Parallel engagement of syndecan-4 causes redistribution of the tyrosine-phosphorylated pool of p190RhoGAP between membrane and cytosolic fractions by a mechanism that requires direct activation of protein kinase C α by syndecan-4. Activation of both pathways is necessary for the efficient regulation of RhoA and, as a consequence, focal adhesion formation. Accordingly, we identify p190RhoGAP as the convergence point for adhesive signals mediated by α5β1 integrin and syndecan-4. This molecular mechanism explains the cooperation between extracellular matrix receptors during cell adhesion.

scholarly journals DNA Nanobiosensors: An Outlook on Signal Readout Strategies

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Arun Richard Chandrasekaran
Keyword(s):  
Atomic Force Microscopy ◽  
Gel Electrophoresis ◽  
Point Of Care ◽  
Cost Effective ◽  
Diagnostic Tools ◽  
Force Microscopy ◽  
Atomic Force ◽  
Structural Versatility ◽  
Signal Readout

A suite of functionalities and structural versatility makes DNA an apt material for biosensing applications. DNA-based biosensors are cost-effective and sensitive and have the potential to be used as point-of-care diagnostic tools. Along with robustness and biocompatibility, these sensors also provide multiple readout strategies. Depending on the functionality of DNA-based biosensors, a variety of output strategies have been reported: fluorescence- and FRET-based readout, nanoparticle-based colorimetry, spectroscopy-based techniques, electrochemical signaling, gel electrophoresis, and atomic force microscopy.

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