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do Nascimento Amorim MDS, Silva França ÁR, Santos-Oliveira R, Rodrigues Sanches J, Marinho Melo T, Araújo Serra Pinto B, Barbosa LRS, Alencar LMR. Atomic Force Microscopy Applied to the Study of Tauopathies. ACS Chem Neurosci 2024; 15:699-715. [PMID: 38305187 DOI: 10.1021/acschemneuro.3c00819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2024] Open
Abstract
Atomic force microscopy (AFM) is a scanning probe microscopy technique which has a physical principle, the measurement of interatomic forces between a very thin tip and the surface of a sample, allowing the obtaining of quantitative data at the nanoscale, contributing to the surface study and mechanical characterization. Due to its great versatility, AFM has been used to investigate the structural and nanomechanical properties of several inorganic and biological materials, including neurons affected by tauopathies. Tauopathies are neurodegenerative diseases featured by aggregation of phosphorylated tau protein inside neurons, leading to functional loss and progressive neurotoxicity. In the broad universe of neurodegenerative diseases, tauopathies comprise the most prevalent, with Alzheimer's disease as its main representative. This review highlights the use of AFM as a suitable research technique for the study of cellular damages in tauopathies, even in early stages, allowing elucidation of pathogenic mechanisms of these diseases.
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Affiliation(s)
- Maria do Socorro do Nascimento Amorim
- Laboratory of Biophysics and Nanosystems, Department of Physics, Federal University of Maranhão, Campus Bacanga, São Luís 65080-805, Maranhão, Brazil
| | - Álefe Roger Silva França
- Laboratory of Biophysics and Nanosystems, Department of Physics, Federal University of Maranhão, Campus Bacanga, São Luís 65080-805, Maranhão, Brazil
| | - Ralph Santos-Oliveira
- Nuclear Engineering Institute, Brazilian Nuclear Energy Commission, Rio de Janeiro 21941906, Brazil
- Laboratory of Nanoradiopharmacy, Rio de Janeiro State University, Rio de Janeiro 23070200, Brazil
| | - Jonas Rodrigues Sanches
- Laboratory of Experimental Physiology, Department of Physiological Sciences, Federal University of Maranhão, Campus Bacanga, São Luís, 65080-805, Maranhão, Brazil
| | - Thamys Marinho Melo
- Laboratory of Experimental Physiology, Department of Physiological Sciences, Federal University of Maranhão, Campus Bacanga, São Luís, 65080-805, Maranhão, Brazil
| | - Bruno Araújo Serra Pinto
- Laboratory of Experimental Physiology, Department of Physiological Sciences, Federal University of Maranhão, Campus Bacanga, São Luís, 65080-805, Maranhão, Brazil
| | - Leandro R S Barbosa
- Department of General Physics, Institute of Physics, University of São Paulo, São Paulo 05508-000, SP, Brazil
- Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas 13083-100, SP, Brazil
| | - Luciana Magalhães Rebelo Alencar
- Laboratory of Biophysics and Nanosystems, Department of Physics, Federal University of Maranhão, Campus Bacanga, São Luís 65080-805, Maranhão, Brazil
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Cruz-Wegener C, Kutell J, Aldaher L, deHaseth N, Bhattacharya SK, Ziebarth N. Quantifying ABCA1/apoA-1 Signaling Pathways with AFM Imaging and Lipidomic Analysis. Methods Mol Biol 2024; 2816:205-222. [PMID: 38977601 DOI: 10.1007/978-1-0716-3902-3_19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
The role of lipid metabolic pathways in the pathophysiology of primary open-angle glaucoma (POAG) has been thoroughly elucidated, with pathways involved in lipid-related disorders such as hypercholesterolemia and hyperlipoprotein accumulation being of particular interest. The ABCA1/apoA-1 transduction pathway moderates reverse cholesterol transport (RCT), facilitating the transport of free cholesterol (FC) and phospholipids (PL) and preventing intracellular lipid aggregates in retinal ganglion cells (RGCs) due to excess FCs and PLs. A deficiency of ABCA1 transporters, and thus, dysregulation of the ABCA1/apoA-1 transduction pathway, may potentiate cellular lipid accumulation, which affects the structural and mechanical features of the cholesterol-rich RGC membranes. Atomic force microscopy (AFM) is a cutting-edge imaging technique suitable for imaging topographical surfaces of a biological specimen and determining its mechanical properties and structural features. The versatility and precision of this technique may prove beneficial in understanding the effects of ABCA1/apoA-1 pathway downregulation and decreased cholesterol efflux in RGCs and their membranes. In this protocol, ABCA1-/- RGC mouse models are prepared over the course of 3 days and are then compared with non-knockout ABCA1 RGC mouse models through AFM imaging of topographical surfaces to examine the difference in membrane dynamics of knockout vs. non-knockout models. Intracellular and extracellular levels of lipids are quantified through high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS).
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Affiliation(s)
- Carolina Cruz-Wegener
- Bascom Palmer Eye Institute, Miami Integrative Metabolomics Research Center, University of Miami, Miami, FL, USA
| | - Jonah Kutell
- Bascom Palmer Eye Institute, Miami Integrative Metabolomics Research Center, University of Miami, Miami, FL, USA
| | - Louay Aldaher
- Bascom Palmer Eye Institute, Miami Integrative Metabolomics Research Center, University of Miami, Miami, FL, USA
| | - Noa deHaseth
- Bascom Palmer Eye Institute, Miami Integrative Metabolomics Research Center, University of Miami, Miami, FL, USA
- Department of Biomedical Engineering, University of Miami, Coral Gables, USA
| | - Sanjoy K Bhattacharya
- Bascom Palmer Eye Institute, Miller School of Medicine at University of Miami, Miami, FL, USA
- Miami Integrative Metabolomics Research Center, Miami, FL, USA
| | - Noel Ziebarth
- Bascom Palmer Eye Institute, Miami Integrative Metabolomics Research Center, University of Miami, Miami, FL, USA.
- Department of Biomedical Engineering, University of Miami, Coral Gables, USA.
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Saunders C, de Villiers CA, Stevens MM. Single Particle Chemical Characterisation of Nanoformulations for Cargo Delivery. AAPS J 2023; 25:94. [PMID: 37783923 DOI: 10.1208/s12248-023-00855-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 08/25/2023] [Indexed: 10/04/2023] Open
Abstract
Nanoparticles can encapsulate a range of therapeutics, from small molecule drugs to sensitive biologics, to significantly improve their biodistribution and biostability. Whilst the regulatory approval of several of these nanoformulations has proven their translatability, there remain several hurdles to the translation of future nanoformulations, leading to a high rate of candidate nanoformulations failing during the drug development process. One barrier is that the difficulty in tightly controlling nanoscale particle synthesis leads to particle-to-particle heterogeneity, which hinders manufacturing and quality control, and regulatory quality checks. To understand and mitigate this heterogeneity requires advancements in nanoformulation characterisation beyond traditional bulk methods to more precise, single particle techniques. In this review, we compare commercially available single particle techniques, with a particular focus on single particle Raman spectroscopy, to provide a guide to adoption of these methods into development workflows, to ultimately reduce barriers to the translation of future nanoformulations.
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Affiliation(s)
- Catherine Saunders
- Department of Materials, Department of Bioengineering, and Institute of Biomedical Engineering, Imperial College London, London, SW7 2AZ, UK
| | - Camille A de Villiers
- Department of Materials, Department of Bioengineering, and Institute of Biomedical Engineering, Imperial College London, London, SW7 2AZ, UK
| | - Molly M Stevens
- Department of Materials, Department of Bioengineering, and Institute of Biomedical Engineering, Imperial College London, London, SW7 2AZ, UK.
- The Kavli Institute for Nanoscience Discovery, University of Oxford, Oxford, OX1 3QU, UK.
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, UK.
- Institute of Biomedical Engineering, University of Oxford, Oxford, OX3 7DQ, UK.
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Byvalov AA, Belozerov VS, Ananchenko BA, Konyshev IV. Specific and Nonspecific Interactions of Yersinia pseudotuberculosis Lipopolysaccharide with Monoclonal Antibodies Assessed by Atomic Force Microscopy. Biophysics (Nagoya-shi) 2022. [DOI: 10.1134/s0006350922060033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023] Open
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Torralba J, de la Arada I, Partida-Hanon A, Rujas E, Arribas M, Insausti S, Valotteau C, Valle J, Andreu D, Caaveiro JMM, Jiménez MA, Apellániz B, Redondo-Morata L, Nieva JL. Molecular recognition of a membrane-anchored HIV-1 pan-neutralizing epitope. Commun Biol 2022; 5:1265. [DOI: 10.1038/s42003-022-04219-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 11/03/2022] [Indexed: 11/19/2022] Open
Abstract
AbstractAntibodies against the carboxy-terminal section of the membrane-proximal external region (C-MPER) of the HIV-1 envelope glycoprotein (Env) are considered as nearly pan-neutralizing. Development of vaccines capable of producing analogous broadly neutralizing antibodies requires deep understanding of the mechanism that underlies C-MPER recognition in membranes. Here, we use the archetypic 10E8 antibody and a variety of biophysical techniques including single-molecule approaches to study the molecular recognition of C-MPER in membrane mimetics. In contrast to the assumption that an interfacial MPER helix embodies the entire C-MPER epitope recognized by 10E8, our data indicate that transmembrane domain (TMD) residues contribute to binding affinity and specificity. Moreover, anchoring to membrane the helical C-MPER epitope through the TMD augments antibody binding affinity and relieves the effects exerted by the interfacial MPER helix on the mechanical stability of the lipid bilayer. These observations support that addition of TMD residues may result in more efficient and stable anti-MPER vaccines.
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Nie J, Tian F, Zheng B, Wang Z, Zheng P. Exploration of Metal-Ligand Coordination Bonds in Proteins by Single-molecule Force Spectroscopy. CHEM LETT 2021. [DOI: 10.1246/cl.210307] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Jingyuan Nie
- State Key Laboratory of Coordination Chemistry, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, Jiangsu 210023, P. R. China
| | - Fang Tian
- State Key Laboratory of Coordination Chemistry, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, Jiangsu 210023, P. R. China
| | - Bin Zheng
- State Key Laboratory of Coordination Chemistry, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, Jiangsu 210023, P. R. China
| | - Ziyi Wang
- State Key Laboratory of Coordination Chemistry, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, Jiangsu 210023, P. R. China
| | - Peng Zheng
- State Key Laboratory of Coordination Chemistry, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, Jiangsu 210023, P. R. China
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Bian K, Gerber C, Heinrich AJ, Müller DJ, Scheuring S, Jiang Y. Scanning probe microscopy. ACTA ACUST UNITED AC 2021. [DOI: 10.1038/s43586-021-00033-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Paananen A, Weich S, Szilvay GR, Leitner M, Tappura K, Ebner A. Quantifying biomolecular hydrophobicity: Single molecule force spectroscopy of class II hydrophobins. J Biol Chem 2021; 296:100728. [PMID: 33933454 PMCID: PMC8164047 DOI: 10.1016/j.jbc.2021.100728] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 04/25/2021] [Accepted: 04/28/2021] [Indexed: 11/30/2022] Open
Abstract
Hydrophobins are surface-active proteins produced by filamentous fungi. The amphiphilic structure of hydrophobins is very compact, containing a distinct hydrophobic patch on one side of the molecule, locked by four intramolecular disulfide bridges. Hydrophobins form dimers and multimers in solution to shield these hydrophobic patches from water exposure. Multimer formation in solution is dynamic, and hydrophobin monomers can be exchanged between multimers. Unlike class I hydrophobins, class II hydrophobins assemble into highly ordered films at the air-water interface. In order to increase our understanding of the strength and nature of the interaction between hydrophobins, we used atomic force microscopy for single molecule force spectroscopy to explore the molecular interaction forces between class II hydrophobins from Trichoderma reesei under different environmental conditions. A genetically engineered hydrophobin variant, NCys-HFBI, enabled covalent attachment of proteins to the apex of the atomic force microscopy cantilever tip and sample surfaces in controlled orientation with sufficient freedom of movement to measure molecular forces between hydrophobic patches. The measured rupture force between two assembled hydrophobins was ∼31 pN, at a loading rate of 500 pN/s. The results indicated stronger interaction between hydrophobins and hydrophobic surfaces than between two assembling hydrophobin molecules. Furthermore, this interaction was stable under different environmental conditions, which demonstrates the dominance of hydrophobicity in hydrophobin-hydrophobin interactions. This is the first time that interaction forces between hydrophobin molecules, and also between naturally occurring hydrophobic surfaces, have been measured directly at a single-molecule level.
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Affiliation(s)
- Arja Paananen
- Industrial Biotechnology and Food, VTT Technical Research Centre of Finland Ltd, Espoo, Finland.
| | - Sabine Weich
- Department of Applied Experimental Biophysics, Institute of Biophysics, Johannes Kepler University Linz, Linz, Austria
| | - Géza R Szilvay
- Industrial Biotechnology and Food, VTT Technical Research Centre of Finland Ltd, Espoo, Finland
| | - Michael Leitner
- Department of Applied Experimental Biophysics, Institute of Biophysics, Johannes Kepler University Linz, Linz, Austria
| | - Kirsi Tappura
- Industrial Biotechnology and Food, VTT Technical Research Centre of Finland Ltd, Espoo, Finland
| | - Andreas Ebner
- Department of Applied Experimental Biophysics, Institute of Biophysics, Johannes Kepler University Linz, Linz, Austria.
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Song G, Tian F, Liu H, Li G, Zheng P. Pioglitazone Inhibits Metal Cluster Transfer of mitoNEET by Stabilizing the Labile Fe-N Bond Revealed at Single-Bond Level. J Phys Chem Lett 2021; 12:3860-3867. [PMID: 33856229 DOI: 10.1021/acs.jpclett.0c03852] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Outer mitochondrial membrane protein mitoNEET (mNT) is a target of the type 2 diabetes drug pioglitazone. It contains a labile Fe2S2(His)1(Cys)3 metal cluster with a single Fe-N(His87) coordinating bond and can transfer its cluster to acceptor proteins. Previous ensemble studies showed that pioglitazone's binding inhibited the transfer by stabilizing the cluster, and histidine 87 may be the key mediator. Here we used atomic force microscopy-based single-molecule force spectroscopy (AFM-SMFS) to study the unfolding process of mNT dimer in the absence and presence of pioglitazone, which can distinguish the binding effect for different regions of a protein. By developing a two-step strategy using different mNT monomers with respective purification tags, we solve the problem that the classic polyprotein formation disables the mNT to dimerize. As a result, a polyprotein including a stable, naturally noncovalently bound mNT homodimer is obtained, which is required for reliable AFM measurement and pioglitazone binding. Then, the dissociation rate (koff) of the metal cluster was measured, showing a 10-fold decrease upon pioglitazone binding, while the other parts decreased only 3-fold, verifying that pioglitazone mainly stabilizes the cluster. Moreover, when the Fe(III)-N(His87) bond was ruptured, this effect for the remaining Fe2S2(Cys)3 intermediate largely disappeared. Consequently, AFM results revealed that pioglitazone inhibited the metal cluster transfer of mNT by stabilizing the labile Fe(III)-N(His87) bond. In addition, an alternative method to build a natural, noncovalently bound protein dimer or complex for reliable single-molecule measurement was developed.
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Affiliation(s)
- Guobin Song
- State Key Laboratory of Coordination Chemistry, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, Jiangsu 210023, P.R. China
| | - Fang Tian
- State Key Laboratory of Coordination Chemistry, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, Jiangsu 210023, P.R. China
| | - Huaxing Liu
- State Key Laboratory of Coordination Chemistry, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, Jiangsu 210023, P.R. China
| | - Guoqiang Li
- State Key Laboratory of Coordination Chemistry, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, Jiangsu 210023, P.R. China
| | - Peng Zheng
- State Key Laboratory of Coordination Chemistry, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, Jiangsu 210023, P.R. China
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Alvisi N, Gutiérrez-Mejía FA, Lokker M, Lin YT, de Jong AM, van Delft F, de Vries R. Self-Assembly of Elastin-like Polypeptide Brushes on Silica Surfaces and Nanoparticles. Biomacromolecules 2021; 22:1966-1979. [PMID: 33871996 PMCID: PMC8154268 DOI: 10.1021/acs.biomac.1c00067] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Control over the placement and activity of biomolecules on solid surfaces is a key challenge in bionanotechnology. While covalent approaches excel in performance, physical attachment approaches excel in ease of processing, which is equally important in many applications. We show how the precision of recombinant protein engineering can be harnessed to design and produce protein-based diblock polymers with a silica-binding and highly hydrophilic elastin-like domain that self-assembles on silica surfaces and nanoparticles to form stable polypeptide brushes that can be used as a scaffold for later biofunctionalization. From atomic force microscopy-based single-molecule force spectroscopy, we find that individual silica-binding peptides have high unbinding rates. Nevertheless, from quartz crystal microbalance measurements, we find that the self-assembled polypeptide brushes cannot easily be rinsed off. From atomic force microscopy imaging and bulk dynamic light scattering, we find that the binding to silica induces fibrillar self-assembly of the peptides. Hence, we conclude that the unexpected stability of these self-assembled polypeptide brushes is at least in part due to peptide-peptide interactions of the silica-binding blocks at the silica surface.
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Affiliation(s)
- Nicolò Alvisi
- Physical Chemistry and Soft Matter, Wageningen University and Research, Stippeneng 4, Wageningen 6708 WE, The Netherlands
| | - Fabiola A Gutiérrez-Mejía
- Physical Chemistry and Soft Matter, Wageningen University and Research, Stippeneng 4, Wageningen 6708 WE, The Netherlands
| | - Meike Lokker
- Physical Chemistry and Soft Matter, Wageningen University and Research, Stippeneng 4, Wageningen 6708 WE, The Netherlands
| | - Yu-Ting Lin
- Department of Applied Physics and Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology, Eindhoven 5600 MB, The Netherlands
| | - Arthur M de Jong
- Department of Applied Physics and Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology, Eindhoven 5600 MB, The Netherlands
| | - Floris van Delft
- Laboratory of Organic Chemistry, Wageningen University and Research, Stippeneng 4, Wageningen 6708 WE, The Netherlands
| | - Renko de Vries
- Physical Chemistry and Soft Matter, Wageningen University and Research, Stippeneng 4, Wageningen 6708 WE, The Netherlands
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Ananchenko B, Belozerov V, Byvalov A, Konyshev I, Korzhavina A, Dudina L. Evaluation of intermolecular forces between lipopolysaccharides and monoclonal antibodies using atomic force microscopy. Int J Biol Macromol 2020; 156:841-850. [PMID: 32305368 DOI: 10.1016/j.ijbiomac.2020.04.055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 03/20/2020] [Accepted: 04/06/2020] [Indexed: 11/19/2022]
Abstract
Understanding of interactions between a bacterium and an immune or non-immune host organism at the cellular and subcellular level is important in order to improve new and existing immunobiological tools for the treatment of bacterial infections (including pseudotuberculosis). The aim of this work was to quantify the interaction force between Yersinia pseudotuberculosis and monoclonal antibodies (mAbs) in the model system "lipopolysaccharide (LPS) - mAbs" by atomic force microscopy (AFM). Our research findings provided the methodical approaches to force measurements between an AFM probe, which was functionalized with Y. pseudotuberculosis LPS, and mica coated by different mAbs. Based on the criteria for force estimation there was shown a greater binding force in the system "LPS - complementary mAbs" than in the system "LPS - heterologous mAbs". In both cases binding force increase followed by increase a contact time between the functionalized AFM probe and mica from 1 to 5 s. It has been shown that single bonds between LPS and complementary mAbs molecules also included a clearly defined non-specific component along with immunochemically specific one. The evidence suggests a significant proportion of applied force exerted to unfolding of high-molecular aggregates whose length may attain many hundreds of nanometers.
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Affiliation(s)
| | - Vladislav Belozerov
- The Institute of Physiology of the Коmi Science Centre of the Ural Branch of the Russian Academy of Sciences, FRC Komi SC UB RAS, Syktyvkar, Komi Republic 167982, Russian Federation; Vyatka State University, Kirov 610000, Russian Federation
| | - Andrey Byvalov
- The Institute of Physiology of the Коmi Science Centre of the Ural Branch of the Russian Academy of Sciences, FRC Komi SC UB RAS, Syktyvkar, Komi Republic 167982, Russian Federation; Vyatka State University, Kirov 610000, Russian Federation.
| | - Ilya Konyshev
- The Institute of Physiology of the Коmi Science Centre of the Ural Branch of the Russian Academy of Sciences, FRC Komi SC UB RAS, Syktyvkar, Komi Republic 167982, Russian Federation; Vyatka State University, Kirov 610000, Russian Federation
| | | | - Lyubov Dudina
- The Institute of Physiology of the Коmi Science Centre of the Ural Branch of the Russian Academy of Sciences, FRC Komi SC UB RAS, Syktyvkar, Komi Republic 167982, Russian Federation; Vyatka State University, Kirov 610000, Russian Federation
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Çolak A, Li B, Blass J, Koynov K, Del Campo A, Bennewitz R. The mechanics of single cross-links which mediate cell attachment at a hydrogel surface. NANOSCALE 2019; 11:11596-11604. [PMID: 31169854 DOI: 10.1039/c9nr01784d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The response of cultured cells to the mechanical properties of hydrogel substrates depends ultimately on the response of single crosslinks to external forces exerted at cell attachment points. We prepared hydrogels by co-polymerization of poly(ethylene glycol diacrylate) (PEGDA) and carboxy poly(ethylene glycol) acrylate (ACPEG-COOH) and confirmed fibroblast spreading on the hydrogel after the ACPEG linker was functionalized with the RGD cell adhesive motif. We performed specific force spectroscopy experiments on the same ACPEG linkers in order to probe the mechanics of single cross-links which mediate the cell attachment and spreading. Measurements were performed with tips of an atomic force microscope (AFM) functionalized with streptavidin and ACPEG linkers functionalized with biotin. We compared hydrogels of varying elastic modulus between 4 and 41 kPa which exhibited significant differences in cell spreading. An effective spring constant for the displacement of single cross-links at the hydrogel surface was derived from the distributions of rupture force and molecular stiffness. A factor of ten in the elastic modulus E of the hydrogel corresponded to a factor of five in the effective spring constant k of single crosslinks, indicating a transition in scaling with the mesh size ξ from the macroscopic E∝ξ-3 to the molecular k∝ξ-2. The quantification of stiffness and deformation at the molecular length scale contributes to the discussion of mechanisms in force-regulated phenomena in cell biology.
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Affiliation(s)
- Arzu Çolak
- INM - Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany.
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