1
|
Leontev A, Rozental L, Freger V. Dynamics of underwater microparticle adhesion to soft hydrated surfaces: Modeling and analysis by time-dependent AFM force spectroscopy. J Colloid Interface Sci 2023; 651:464-476. [PMID: 37556904 DOI: 10.1016/j.jcis.2023.07.185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 07/23/2023] [Accepted: 07/28/2023] [Indexed: 08/11/2023]
Abstract
HYPOTHESIS Understanding the attachment and detachment of microparticles and living cells to surfaces is crucial for developing antifouling strategies. Hydrogel coatings have shown promise in reducing fouling and particle adhesion due to their softness and high water content, yet the mechanisms involved are dynamic and complex, and relevant parameters are not easily accessible. AFM-based force spectroscopy (FS) experiments with colloidal probe particles is a direct way of evaluating adhesive and mechanical relaxational dynamics, yet their interpretation and modeling has been challenging. The present study proposes and examines several dynamic models, suitable for quantitative analysis of FS results with model probe particle on hydrogels surfaces. EXPERIMENTS FS were performed using polyethylene glycol (PEG) hydrogels and polystyrene microspheres including particle attachement to the hydrogel surface (loading), holding the particle on the surface with a constant force for variable times (dwell) and pulling the particle away from the surface (unloading) FINDINGS: It was found that a viscoelastic extension of the classical JKR model with energy of adhesion unevenly distributed over the contact area and vanishing at its circumferences accurately described all FS experiments and yielded physically consistent viscoelastic and adhesive dynamic parameters, steadily changing with dwell time and applied force. The observed time evolution and force dependence were rationalized as combination of osmotic and osmo-mechnical relaxation in the contact region.
Collapse
Affiliation(s)
- Aleksandr Leontev
- Wolfson Department of Chemical Engineering, Technion - IIT, Haifa, Israel
| | - Lina Rozental
- Wolfson Department of Chemical Engineering, Technion - IIT, Haifa, Israel
| | - Viatcheslav Freger
- Wolfson Department of Chemical Engineering, Technion - IIT, Haifa, Israel; Grand Technion Energy Program, Technion - IIT, Haifa, Israel; Russel Berrie Nanotechnology Institute, Technion - IIT, Haifa, Israel.
| |
Collapse
|
2
|
Siddiquie RY, Sharma K, Banerjee A, Agrawal A, Joshi SS. Time-dependent plastic behavior of bacteria leading to rupture. J Mech Behav Biomed Mater 2023; 145:106048. [PMID: 37523842 DOI: 10.1016/j.jmbbm.2023.106048] [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: 06/07/2023] [Revised: 07/25/2023] [Accepted: 07/26/2023] [Indexed: 08/02/2023]
Abstract
A study of the mechanical response of bacteria is essential in designing an antibacterial surface for implants and food packaging applications. This research evaluated the mechanical response of Escherichia coli under different loading conditions. Indentation and prolonged creep tests were performed to understand their viscoelastic-plastic response. The results indicate that varying loading rates from 1 μm/s to 5 μm/s show an increase in modulus of 182% and 90%, calculated in the loading and unloading cycles, respectively, and a decrease in adhesion force by 42%. However, on varying loads from 5 nN to 25 nN, nominal change is observed in both modulus and adhesion force. The rupture curve at 100 nN load shows elastic and a small plastic deformation accompanied by a sharp peak indicating the cell wall rupture. The rupture force at the peak was found to be 34.38 ± 5.15 nN, irrespective of the loading rate, making it a failure criterion for bacteria rupture. The creep response of bacteria increases (for 6 s) and then remains constant (for 15 s) with time, indicating that a standard linear solid (SLS) model applies to this behavior. This work attempts to evaluate the mechanical properties of E. coli bacteria focusing on its rupture by contact killing mechanism.
Collapse
Affiliation(s)
- Reshma Y Siddiquie
- Department of Mechanical Engineering, Indian Institute of Technology, Bombay, India
| | - Kuldeep Sharma
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Bombay, India
| | - Anirban Banerjee
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Bombay, India
| | - Amit Agrawal
- Department of Mechanical Engineering, Indian Institute of Technology, Bombay, India
| | - Suhas S Joshi
- Department of Mechanical Engineering, Indian Institute of Technology, Bombay, India; Department of Mechanical Engineering, Indian Institute of Technology, Indore, India.
| |
Collapse
|
3
|
Savin N, Erofeev A, Gorelkin P. Analytical Models for Measuring the Mechanical Properties of Yeast. Cells 2023; 12:1946. [PMID: 37566025 PMCID: PMC10417110 DOI: 10.3390/cells12151946] [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: 06/05/2023] [Revised: 07/21/2023] [Accepted: 07/26/2023] [Indexed: 08/12/2023] Open
Abstract
The mechanical properties of yeast play an important role in many biological processes, such as cell division and growth, maintenance of internal pressure, and biofilm formation. In addition, the mechanical properties of cells can indicate the degree of damage caused by antifungal drugs, as the mechanical parameters of healthy and damaged cells are different. Over the past decades, atomic force microscopy (AFM) and micromanipulation have become the most widely used methods for evaluating the mechanical characteristics of microorganisms. In this case, the reliability of such an estimate depends on the choice of mathematical model. This review presents various analytical models developed in recent years for studying the mechanical properties of both cells and their individual structures. The main provisions of the applied approaches are described along with their limitations and advantages. Attention is paid to the innovative method of low-invasive nanomechanical mapping with scanning ion-conductance microscopy (SICM), which is currently starting to be successfully used in the discovery of novel drugs acting on the yeast cell wall and plasma membrane.
Collapse
Affiliation(s)
- Nikita Savin
- Research Laboratory of Biophysics, National University of Science and Technology MISiS, Moscow 119049, Russia;
| | - Alexander Erofeev
- Research Laboratory of Biophysics, National University of Science and Technology MISiS, Moscow 119049, Russia;
| | | |
Collapse
|
4
|
Najera J, Rosenberger MR, Datta M. Atomic Force Microscopy Methods to Measure Tumor Mechanical Properties. Cancers (Basel) 2023; 15:3285. [PMID: 37444394 DOI: 10.3390/cancers15133285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 06/17/2023] [Accepted: 06/20/2023] [Indexed: 07/15/2023] Open
Abstract
Atomic force microscopy (AFM) is a popular tool for evaluating the mechanical properties of biological materials (cells and tissues) at high resolution. This technique has become particularly attractive to cancer researchers seeking to bridge the gap between mechanobiology and cancer initiation, progression, and treatment resistance. The majority of AFM studies thus far have been extensively focused on the nanomechanical characterization of cells. However, these approaches fail to capture the complex and heterogeneous nature of a tumor and its host organ. Over the past decade, efforts have been made to characterize the mechanical properties of tumors and tumor-bearing tissues using AFM. This has led to novel insights regarding cancer mechanopathology at the tissue scale. In this Review, we first explain the principles of AFM nanoindentation for the general study of tissue mechanics. We next discuss key considerations when using this technique and preparing tissue samples for analysis. We then examine AFM application in characterizing the mechanical properties of cancer tissues. Finally, we provide an outlook on AFM in the field of cancer mechanobiology and its application in the clinic.
Collapse
Affiliation(s)
- Julian Najera
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Matthew R Rosenberger
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Meenal Datta
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556, USA
| |
Collapse
|
5
|
Dejosez M, Dall'Agnese A, Ramamoorthy M, Platt J, Yin X, Hogan M, Brosh R, Weintraub AS, Hnisz D, Abraham BJ, Young RA, Zwaka TP. Regulatory architecture of housekeeping genes is driven by promoter assemblies. Cell Rep 2023; 42:112505. [PMID: 37182209 PMCID: PMC10329844 DOI: 10.1016/j.celrep.2023.112505] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 01/22/2023] [Accepted: 04/28/2023] [Indexed: 05/16/2023] Open
Abstract
Genes that are key to cell identity are generally regulated by cell-type-specific enhancer elements bound by transcription factors, some of which facilitate looping to distant gene promoters. In contrast, genes that encode housekeeping functions, whose regulation is essential for normal cell metabolism and growth, generally lack interactions with distal enhancers. We find that Ronin (Thap11) assembles multiple promoters of housekeeping and metabolic genes to regulate gene expression. This behavior is analogous to how enhancers are brought together with promoters to regulate cell identity genes. Thus, Ronin-dependent promoter assemblies provide a mechanism to explain why housekeeping genes can forgo distal enhancer elements and why Ronin is important for cellular metabolism and growth control. We propose that clustering of regulatory elements is a mechanism common to cell identity and housekeeping genes but is accomplished by different factors binding distinct control elements to establish enhancer-promoter or promoter-promoter interactions, respectively.
Collapse
Affiliation(s)
- Marion Dejosez
- Black Family Stem Cell Institute, Huffington Center for Cell-based Research in Parkinson's Disease, Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10502, USA
| | - Alessandra Dall'Agnese
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Mahesh Ramamoorthy
- Black Family Stem Cell Institute, Huffington Center for Cell-based Research in Parkinson's Disease, Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10502, USA
| | - Jesse Platt
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Xing Yin
- Black Family Stem Cell Institute, Huffington Center for Cell-based Research in Parkinson's Disease, Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10502, USA
| | - Megan Hogan
- Black Family Stem Cell Institute, Huffington Center for Cell-based Research in Parkinson's Disease, Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10502, USA
| | - Ran Brosh
- Black Family Stem Cell Institute, Huffington Center for Cell-based Research in Parkinson's Disease, Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10502, USA
| | - Abraham S Weintraub
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Denes Hnisz
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Brian J Abraham
- St. Jude Research Children's Hospital, Memphis, TN 38105, USA
| | - Richard A Young
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.
| | - Thomas P Zwaka
- Black Family Stem Cell Institute, Huffington Center for Cell-based Research in Parkinson's Disease, Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10502, USA.
| |
Collapse
|
6
|
Park H, Schwartzman AF, Tang TC, Wang L, Lu TK. Ultra-lightweight living structural material for enhanced stiffness and environmental sensing. Mater Today Bio 2022; 18:100504. [PMID: 36504543 PMCID: PMC9729073 DOI: 10.1016/j.mtbio.2022.100504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 11/20/2022] [Accepted: 11/22/2022] [Indexed: 11/27/2022]
Abstract
Natural materials such as bone, wood, and bamboo can inspire the fabrication of stiff, lightweight structural materials. Biofilms are one of the most dominant forms of life in nature. However, little is known about their physical properties as a structural material. Here we report an Escherichia coli biofilm having a Young's modulus close to 10 GPa with ultra-low density, indicating a high-performance structural material. The mechanical and structural characterization of the biofilm and its components illuminates its adaptable bottom-up design, consisting of lightweight microscale cells covered by a dense network of amyloid nanofibrils on the surface. We engineered E. coli such that 1) carbon nanotubes assembled on the biofilm, enhancing its stiffness to over 30 GPa, or that 2) the biofilm sensitively detected heavy metal as an example of an environmental toxin. These demonstrations offer new opportunities for developing responsive living structural materials to serve many real-world applications.
Collapse
Affiliation(s)
- Heechul Park
- Synthetic Biology Group, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA,Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA,Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Alan F. Schwartzman
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Tzu-Chieh Tang
- Synthetic Biology Group, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA,Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA,Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Lei Wang
- Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Timothy K. Lu
- Synthetic Biology Group, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA,Synthetic Biology Center, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA,Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA,Corresponding author. Synthetic Biology Group, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
| |
Collapse
|
7
|
Lekka M. Applicability of atomic force microscopy to determine cancer-related changes in cells. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2022; 380:20210346. [PMID: 35909354 DOI: 10.1098/rsta.2021.0346] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 02/24/2022] [Indexed: 06/15/2023]
Abstract
The determination of mechanical properties of living cells as an indicator of cancer progression has become possible with the development of local measurement techniques such as atomic force microscopy (AFM). Its most important advantage is a nanoscopic character, implying that very local alterations can be quantified. The results gathered from AFM measurements of various cancers show that, for most cancers, individual cells are characterized by the lower apparent Young's modulus, denoting higher cell deformability. The measured value depends on various factors, like the properties of substrates used for cell growth, force loading rate or indentation depth. Despite this, the results proved the AFM capability to recognize mechanically altered cells. This can significantly impact the development of methodological approaches toward the precise identification of pathological cells. This article is part of the theme issue 'Nanocracks in nature and industry'.
Collapse
Affiliation(s)
- Małgorzata Lekka
- Department of Biophysical Microstructures, Institute of Nuclear Physics, Polish Academy of Sciences, PL-31342 Krakow, Poland
| |
Collapse
|
8
|
Cui Y, Leong WH, Liu CF, Xia K, Feng X, Gergely C, Liu RB, Li Q. Revealing Capillarity in AFM Indentation of Cells by Nanodiamond-Based Nonlocal Deformation Sensing. NANO LETTERS 2022; 22:3889-3896. [PMID: 35507005 DOI: 10.1021/acs.nanolett.1c05037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Nanoindentation based on atomic force microscopy (AFM) can measure the elasticity of biomaterials and cells with high spatial resolution and sensitivity, but relating the data to quantitative mechanical properties depends on information on the local contact, which is unclear in most cases. Here, we demonstrate nonlocal deformation sensing on biorelevant soft matters upon AFM indentation by using nitrogen-vacancy centers in nanodiamonds, providing data for studying both the elasticity and capillarity without requiring detailed knowledge about the local contact. Using fixed HeLa cells for demonstration, we show that the apparent elastic moduli of the cells would have been overestimated if the capillarity was not considered. In addition, we observe that both the elastic moduli and the surface tensions are reduced after depolymerization of the actin cytoskeleton in cells. This work demonstrates that the nanodiamond sensing of nonlocal deformation with nanometer precision is particularly suitable for studying mechanics of soft biorelevant materials.
Collapse
Affiliation(s)
- Yue Cui
- Department of Physics, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Weng-Hang Leong
- Department of Physics, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Chu-Feng Liu
- Department of Physics, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Kangwei Xia
- Department of Physics, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Xi Feng
- Department of Physics, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Csilla Gergely
- Laboratoire Charles Coulomb, University of Montpellierr, CNRS, Montpellier, 34095, France
| | - Ren-Bao Liu
- Department of Physics, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
- Centre for Quantum Coherence, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
- The Hong Kong Institute of Quantum Information Science and Technology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Quan Li
- Department of Physics, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
- Centre for Quantum Coherence, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
- The Hong Kong Institute of Quantum Information Science and Technology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| |
Collapse
|
9
|
Zhu J, Tian Y, Yan J, Hu J, Wang Z, Liu X. The effects of measurement parameters on the cancerous cell nucleus characterization by atomic force microscopy in vitro. J Microsc 2022; 287:3-18. [PMID: 35411607 PMCID: PMC9322684 DOI: 10.1111/jmi.13104] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 02/25/2022] [Accepted: 03/30/2022] [Indexed: 12/24/2022]
Abstract
Cancer is now responsible for the major leading cause of death worldwide. It is noteworthy that lung cancer has been recognised as the highest incidence (11.6%) and mortality (18.4%) for combined sexes among a variety of cancer diseases. Therefore, it is of great value to investigate the mechanical properties of lung cancerous cells for early diagnosis. This paper focus on the influence of measurement parameters on the measured central Young's moduli of single live A549 cell in vitro based on the force spectroscopy mode of atomic force microscopy (AFM). The effects of the measurement parameters on the measured central Young's moduli were analysed by fitting the force–depth curves utilising the Sneddon model. The results revealed that the Young's moduli of A549 cells increased with the larger indentation force, higher indentation speed, less retraction time, deeper Z length and lower purity percentage of serum. The Young's moduli of cells increased first and then decreased with the increasing dwell time. Hence, this research may have potential significance to provide reference for the standardised detection of a single cancerous cell in vitro using AFM methodologies. Cancer is now responsible for the majority leading cause of death worldwide and it is noteworthy that lung cancer has been recognised as the highest incidence (11.6%) and mortality (18.4%) for combined sexes among a variety of cancer diseases. Therefore, it is of great value to investigate the mechanical properties of lung cancerous cells for early diagnosis. This paper primarily investigated the morphological properties and the influence of measurement parameters on the measured local elastic moduli of single live A549 cell in vitro using the AFM‐based force spectroscopy mode. In practice, there are many factors for incorrect or inaccurate experimental results using AFM to measure the characteristics of live cells, such as non‐homogeneous nature of cells, probe geometry and size, mechanical analysis model, substrate stiffness and different measurement parameters. The various measurement parameters have become the huge impact factor to influence the measurement result. Hence, this research may have potential significance to provide reference for the standardised detection of a single cancerous cell in vitro using AFM methodologies.
Collapse
Affiliation(s)
- Jiajing Zhu
- School of Engineering, University of Warwick, Coventry, CV4 7AL, UK
| | - Yanling Tian
- School of Engineering, University of Warwick, Coventry, CV4 7AL, UK
| | - Jin Yan
- Ministry of Education Key Laboratory for Cross-Scale Micro and Nano Manufacturing, Changchun University of Science and Technology, Changchun, 130022, China.,International Research Centre for Nano Handling and Manufacturing of China, Changchun University of Science and Technology, Changchun, 130022, China
| | - Jing Hu
- Ministry of Education Key Laboratory for Cross-Scale Micro and Nano Manufacturing, Changchun University of Science and Technology, Changchun, 130022, China.,International Research Centre for Nano Handling and Manufacturing of China, Changchun University of Science and Technology, Changchun, 130022, China
| | - Zuobin Wang
- Ministry of Education Key Laboratory for Cross-Scale Micro and Nano Manufacturing, Changchun University of Science and Technology, Changchun, 130022, China.,International Research Centre for Nano Handling and Manufacturing of China, Changchun University of Science and Technology, Changchun, 130022, China
| | - Xianping Liu
- School of Engineering, University of Warwick, Coventry, CV4 7AL, UK
| |
Collapse
|
10
|
Faber J, Hinrichsen J, Greiner A, Reiter N, Budday S. Tissue-Scale Biomechanical Testing of Brain Tissue for the Calibration of Nonlinear Material Models. Curr Protoc 2022; 2:e381. [PMID: 35384412 DOI: 10.1002/cpz1.381] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 01/14/2022] [Indexed: 06/14/2023]
Abstract
Brain tissue is one of the most complex and softest tissues in the human body. Due to its ultrasoft and biphasic nature, it is difficult to control the deformation state during biomechanical testing and to quantify the highly nonlinear, time-dependent tissue response. In numerous experimental studies that have investigated the mechanical properties of brain tissue over the last decades, stiffness values have varied significantly. One reason for the observed discrepancies is the lack of standardized testing protocols and corresponding data analyses. The tissue properties have been tested on different length and time scales depending on the testing technique, and the corresponding data have been analyzed based on simplifying assumptions. In this review, we highlight the advantage of using nonlinear continuum mechanics based modeling and finite element simulations to carefully design experimental setups and protocols as well as to comprehensively analyze the corresponding experimental data. We review testing techniques and protocols that have been used to calibrate material model parameters and discuss artifacts that might falsify the measured properties. The aim of this work is to provide standardized procedures to reliably quantify the mechanical properties of brain tissue and to more accurately calibrate appropriate constitutive models for computational simulations of brain development, injury and disease. Computational models can not only be used to predictively understand brain tissue behavior, but can also serve as valuable tools to assist diagnosis and treatment of diseases or to plan neurosurgical procedures. © 2022 The Authors. Current Protocols published by Wiley Periodicals LLC.
Collapse
Affiliation(s)
- Jessica Faber
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Applied Mechanics, Egerlandstraße 5, 91058 Erlangen, Germany
| | - Jan Hinrichsen
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Applied Mechanics, Egerlandstraße 5, 91058 Erlangen, Germany
| | - Alexander Greiner
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Applied Mechanics, Egerlandstraße 5, 91058 Erlangen, Germany
| | - Nina Reiter
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Applied Mechanics, Egerlandstraße 5, 91058 Erlangen, Germany
| | - Silvia Budday
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Institute of Applied Mechanics, Egerlandstraße 5, 91058 Erlangen, Germany
| |
Collapse
|
11
|
Himori S, Sakata T. Free-standing conductive hydrogel electrode for potentiometric glucose sensing. RSC Adv 2022; 12:5369-5373. [PMID: 35425571 PMCID: PMC8981371 DOI: 10.1039/d1ra08956k] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 02/08/2022] [Indexed: 11/24/2022] Open
Abstract
Flexible conductive polymer hydrogels are attracting attention as an electrode material. Electrochemical biosensors with conductive polymer hydrogels have been developed because they have some advantages such as biocompatibility, high conductivity, 3D nanostructure, solvated surface, and enlarged interface. Conductive polymer hydrogels bearing receptor molecules such as enzymes in its 3D nanostructure enable the detection of target analytes with high sensitivity. However, because such hydrogels are fragile, they cannot stand on their own and a supporting substrate is required to fabricate them. This means that the loss of mechanical toughness is detrimental for their application to flexible biosensors. In this study, we have proposed a free-standing conductive hydrogel electrode with no coating on a substrate, which is composed of polyaniline with phenyl boronic acid including polyvinyl alcohol, for potentiometric glucose sensing. In addition, its electrical responsivity to glucose has been confirmed by investigating its mechanical properties at various glucose concentrations, considering the hydrogel compositions. A free-standing conductive hydrogel electrode with no coating on a substrate is proposed for potentiometric glucose sensing.![]()
Collapse
Affiliation(s)
- Shogo Himori
- Department of Materials Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Toshiya Sakata
- Department of Materials Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
| |
Collapse
|
12
|
Na + i/K + i imbalance contributes to gene expression in endothelial cells exposed to elevated NaCl. Heliyon 2021; 7:e08088. [PMID: 34632152 PMCID: PMC8488490 DOI: 10.1016/j.heliyon.2021.e08088] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 08/27/2021] [Accepted: 09/26/2021] [Indexed: 12/16/2022] Open
Abstract
High-salt consumption contributes to the development of hypertension and is considered an independent risk factor for vascular remodelling, cardiac hypertrophy and stroke incidence. Alterations in NO production, inflammation and endothelial cell stiffening are considered now as plausible mediators of cardiovascular dysfunction. We studied early responses of endothelial cells (HUVEC) caused by a moderate increase in extracellular sodium concentration. Exposure of HUVEC to elevated sodium within the physiological range up to 24 h is accompanied by changes in monovalent cations fluxes and Na,K-ATPase activation, and, in turn, results in a significant decrease in the content of PTGS2, IL6 and IL1LR1 mRNAs. The expression of NOS3 and FOS genes, as well as the abundance of cytosolic and nuclear NFAT5 protein, remained unchanged. We assessed the mechanical properties of endothelial cells by estimating Young's modulus and equivalent elastic constant using atomic force and interference microscopy, respectively. These parameters were unaffected by elevated-salt exposure for 24 h. The data obtained suggest that even small and short-term elevations of extracellular sodium concentration affect the expression of genes involved in the control of endothelial function through the Na+i/K+i-dependent mechanism(s).
Collapse
|
13
|
Collinson DW, Sheridan RJ, Palmeri MJ, Brinson LC. Best practices and recommendations for accurate nanomechanical characterization of heterogeneous polymer systems with atomic force microscopy. Prog Polym Sci 2021. [DOI: 10.1016/j.progpolymsci.2021.101420] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
14
|
Pérez-Calixto D, Amat-Shapiro S, Zamarrón-Hernández D, Vázquez-Victorio G, Puech PH, Hautefeuille M. Determination by Relaxation Tests of the Mechanical Properties of Soft Polyacrylamide Gels Made for Mechanobiology Studies. Polymers (Basel) 2021; 13:629. [PMID: 33672475 PMCID: PMC7923444 DOI: 10.3390/polym13040629] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 02/08/2021] [Accepted: 02/11/2021] [Indexed: 02/04/2023] Open
Abstract
Following the general aim of recapitulating the native mechanical properties of tissues and organs in vitro, the field of materials science and engineering has benefited from recent progress in developing compliant substrates with physical and chemical properties similar to those of biological materials. In particular, in the field of mechanobiology, soft hydrogels can now reproduce the precise range of stiffnesses of healthy and pathological tissues to study the mechanisms behind cell responses to mechanics. However, it was shown that biological tissues are not only elastic but also relax at different timescales. Cells can, indeed, perceive this dissipation and actually need it because it is a critical signal integrated with other signals to define adhesion, spreading and even more complicated functions. The mechanical characterization of hydrogels used in mechanobiology is, however, commonly limited to the elastic stiffness (Young's modulus) and this value is known to depend greatly on the measurement conditions that are rarely reported in great detail. Here, we report that a simple relaxation test performed under well-defined conditions can provide all the necessary information for characterizing soft materials mechanically, by fitting the dissipation behavior with a generalized Maxwell model (GMM). The simple method was validated using soft polyacrylamide hydrogels and proved to be very useful to readily unveil precise mechanical properties of gels that cells can sense and offer a set of characteristic values that can be compared with what is typically reported from microindentation tests.
Collapse
Affiliation(s)
- Daniel Pérez-Calixto
- Departamento de Física, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico; (D.P.-C.); (S.A.-S.); (D.Z.-H.); (G.V.-V.)
- Laboratorio Nacional de Soluciones Biomiméticas para Diagnóstico y Terapia, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
- Posgrado en Ciencia e Ingeniería de Materiales, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
| | - Samuel Amat-Shapiro
- Departamento de Física, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico; (D.P.-C.); (S.A.-S.); (D.Z.-H.); (G.V.-V.)
- Laboratorio Nacional de Soluciones Biomiméticas para Diagnóstico y Terapia, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
| | - Diego Zamarrón-Hernández
- Departamento de Física, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico; (D.P.-C.); (S.A.-S.); (D.Z.-H.); (G.V.-V.)
- Laboratorio Nacional de Soluciones Biomiméticas para Diagnóstico y Terapia, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
| | - Genaro Vázquez-Victorio
- Departamento de Física, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico; (D.P.-C.); (S.A.-S.); (D.Z.-H.); (G.V.-V.)
- Laboratorio Nacional de Soluciones Biomiméticas para Diagnóstico y Terapia, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
| | - Pierre-Henri Puech
- Adhesion and Inflammation Lab (LAI), Aix Marseille University, LAI UM 61, Inserm, UMR_S 1067, CNRS, UMR 7333, F-13288 Marseille, France;
| | - Mathieu Hautefeuille
- Departamento de Física, Facultad de Ciencias, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico; (D.P.-C.); (S.A.-S.); (D.Z.-H.); (G.V.-V.)
- Laboratorio Nacional de Soluciones Biomiméticas para Diagnóstico y Terapia, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
| |
Collapse
|
15
|
Witko T, Baster Z, Rajfur Z, Sofińska K, Barbasz J. Increasing AFM colloidal probe accuracy by optical tweezers. Sci Rep 2021; 11:509. [PMID: 33436725 PMCID: PMC7804458 DOI: 10.1038/s41598-020-79938-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 11/25/2020] [Indexed: 01/29/2023] Open
Abstract
A precise determination of the cantilever spring constant is the critical point of all colloidal probe experiments. Existing methods are based on approximations considering only cantilever geometry and do not take into account properties of any object or substance attached to the cantilever. Neglecting the influence of the colloidal sphere on the cantilever characteristics introduces significant uncertainty in a spring constant determination and affects all further considerations. In this work we propose a new method of spring constant calibration for 'colloidal probe' type cantilevers based on the direct measurement of force constant. The Optical Tweezers based calibration method will help to increase the accuracy and repeatability of the AFM colloidal probe experiments.
Collapse
Affiliation(s)
- Tomasz Witko
- M. Smoluchowski Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348, Kraków, Poland
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, 30-239, Kraków, Poland
| | - Zbigniew Baster
- M. Smoluchowski Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348, Kraków, Poland
| | - Zenon Rajfur
- M. Smoluchowski Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348, Kraków, Poland
| | - Kamila Sofińska
- M. Smoluchowski Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348, Kraków, Poland.
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, 30-239, Kraków, Poland.
| | - Jakub Barbasz
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, 30-239, Kraków, Poland.
| |
Collapse
|
16
|
Weber A, Zbiral B, Iturri J, Benitez R, Toca-Herrera JL. Measuring (biological) materials mechanics with atomic force microscopy. 2. Influence of the loading rate and applied force (colloidal particles). Microsc Res Tech 2020; 84:1078-1088. [PMID: 33179834 DOI: 10.1002/jemt.23643] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 09/25/2020] [Accepted: 10/28/2020] [Indexed: 12/24/2022]
Abstract
Atomic force microscopy (AFM) is the most often used tool to study the mechanical properties of eukaryotic cells. Due to their complex assembly, cells show viscoelastic properties. When performing experiments, one has to consider the influence of both loading rate and maximum load on the measured mechanical properties. Here, we employed colloidal particles of various sizes (from 2 to 20 μm diameter) to perform force spectroscopy measurements on endothelial cells at loading rates varying from 0.1 to 50 μm/s, and maximum loads ranging from 1 to 25 nN. We were able to determine the non-linear dependence of cell viscoelastic properties on the loading rate which followed a weak power law. In addition, we show that previous loading at high forces leads to a stiffening of cells. Based on these results we discuss a road map for determining cell mechanical properties using AFM. Finally, this work provides an experimental framework for cell mechanical measurements using force-cycle experiments.
Collapse
Affiliation(s)
- Andreas Weber
- Department of Nanobiotechnology, Institute for Biophysics, University of Natural Resources and Life Sciences (BOKU), Vienna, Austria
| | - Barbara Zbiral
- Department of Nanobiotechnology, Institute for Biophysics, University of Natural Resources and Life Sciences (BOKU), Vienna, Austria
| | - Jagoba Iturri
- Department of Nanobiotechnology, Institute for Biophysics, University of Natural Resources and Life Sciences (BOKU), Vienna, Austria
| | - Rafael Benitez
- Departamento de Matemáticas para la Economía y la Empresa, Facultad de Economía, Universidad de Valencia, Valencia, Spain
| | - José L Toca-Herrera
- Department of Nanobiotechnology, Institute for Biophysics, University of Natural Resources and Life Sciences (BOKU), Vienna, Austria
| |
Collapse
|
17
|
Zamani E, Johnson TJ, Chatterjee S, Immethun C, Sarella A, Saha R, Dishari SK. Cationic π-Conjugated Polyelectrolyte Shows Antimicrobial Activity by Causing Lipid Loss and Lowering Elastic Modulus of Bacteria. ACS APPLIED MATERIALS & INTERFACES 2020; 12:49346-49361. [PMID: 33089982 PMCID: PMC8926324 DOI: 10.1021/acsami.0c12038] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Cationic, π-conjugated oligo-/polyelectrolytes (CCOEs/CCPEs) have shown great potential as antimicrobial materials to fight against antibiotic resistance. In this work, we treated wild-type and ampicillin-resistant (amp-resistant) Escherichia coli (E. coli) with a promising cationic, π-conjugated polyelectrolyte (P1) with a phenylene-based backbone and investigated the resulting morphological, mechanical, and compositional changes of the outer membrane of bacteria in great detail. The cationic quaternary amine groups of P1 led to electrostatic interactions with negatively charged moieties within the outer membrane of bacteria. Using atomic force microscopy (AFM), high-resolution transmission electron microscopy (TEM), we showed that due to this treatment, the bacterial outer membrane became rougher, decreased in stiffness/elastic modulus (AFM nanoindentation), formed blebs, and released vesicles near the cells. These evidences, in addition to increased staining of the P1-treated cell membrane by lipophilic dye Nile Red (confocal laser scanning microscopy (CLSM)), suggested loosening/disruption of packing of the outer cell envelope and release and exposure of lipid-based components. Lipidomics and fatty acid analysis confirmed a significant loss of phosphate-based outer membrane lipids and fatty acids, some of which are critically needed to maintain cell wall integrity and mechanical strength. Lipidomics and UV-vis analysis also confirmed that the extracellular vesicles released upon treatment (AFM) are composed of lipids and cationic P1. Such surface alterations (vesicle/bleb formation) and release of lipids/fatty acids upon treatment were effective enough to inhibit further growth of E. coli cells without completely disintegrating the cells and have been known as a defense mechanism of the cells against cationic antimicrobial agents.
Collapse
Affiliation(s)
- Ehsan Zamani
- Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
| | - Tyler J. Johnson
- Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
| | - Shyambo Chatterjee
- Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
| | - Cheryl Immethun
- Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
| | - Anandakumar Sarella
- Nebraska Center for Materials and Nanoscience, Voelte-Keegan Nanoscience Research Center, University of Nebraska-Lincoln, Lincoln, NE 68588-0298, United States
| | - Rajib Saha
- Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
| | - Shudipto Konika Dishari
- Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States
- Corresponding author’s ; Phone: 402-472-7537
| |
Collapse
|
18
|
Li Z, Gao S, Brand U, Hiller K, Wolff H. A MEMS nanoindenter with an integrated AFM cantilever gripper for nanomechanical characterization of compliant materials. NANOTECHNOLOGY 2020; 31:305502. [PMID: 32289758 DOI: 10.1088/1361-6528/ab88ed] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
This work presents the development of a MEMS nanoindenter that uses exchangeable AFM probes for quasi-static nanomechanical characterization of compliant and ultra-compliant materials. While the electrostatic micro-force transducer of the MEMS nanoindenter provides a maximum indentation depth up to 9.5 µm with a maximum output force of 600 µN, experimental investigations reveal that it can achieve a depth and force resolution better than 4 pm Hz-1/2 and 0.3 nN Hz-1/2, in air for f≥ 1 Hz. A passive AFM probe gripper is integrated into the MEMS nanoindenter, allowing the nanoindenter to utilize various AFM probes as an indenter for material testing. A proof-of-principle experimental setup has been built to investigate the performance of the MEMS nanoindenter prototype. In proof-of-principle experiments, the prototype with a clamped diamond AFM probe successfully identified an atomic step (∼0.31 nm) within a Si < 111 > ultraflat sample using the scanning probe microscopy mode. The nanomechanical measurement capability of the MEMS nanoindenter prototype has been verified by means of measurements of reference polymer samples using a silicon AFM probe and by means of measurements of the elastic properties of a PDMS sample using a spherical diamond-coated AFM probe. Owing to its compact and low-cost but high-resolution capacitive readout system, this MEMS nanoindenter head can be further applied for in-situ quantitative nanomechanical measurements in AFMs and SEMs.
Collapse
Affiliation(s)
- Z Li
- Physikalisch-Technische Bundesanstalt, 38116, Braunschweig, Germany
| | | | | | | | | |
Collapse
|
19
|
Hierarchically structured polydimethylsiloxane films for ultra-soft neural interfaces. MICRO AND NANO ENGINEERING 2020. [DOI: 10.1016/j.mne.2020.100051] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
20
|
Efremov YM, Okajima T, Raman A. Measuring viscoelasticity of soft biological samples using atomic force microscopy. SOFT MATTER 2020; 16:64-81. [PMID: 31720656 DOI: 10.1039/c9sm01020c] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Mechanical properties play important roles at different scales in biology. At the level of a single cell, the mechanical properties mediate mechanosensing and mechanotransduction, while at the tissue and organ levels, changes in mechanical properties are closely connected to disease and physiological processes. Over the past three decades, atomic force microscopy (AFM) has become one of the most widely used tools in the mechanical characterization of soft samples, ranging from molecules, cell organoids and cells to whole tissue. AFM methods can be used to quantify both elastic and viscoelastic properties, and significant recent developments in the latter have been enabled by the introduction of new techniques and models for data analysis. Here, we review AFM techniques developed in recent years for examining the viscoelastic properties of cells and soft gels, describe the main steps in typical data acquisition and analysis protocols, and discuss relevant viscoelastic models and how these have been used to characterize the specific features of cellular and other biological samples. We also discuss recent trends and potential directions for this field.
Collapse
Affiliation(s)
- Yuri M Efremov
- School of Mechanical Engineering, Purdue University, West Lafayette, Indiana, USA. and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana, USA and Institute for Regenerative Medicine, Sechenov University, Moscow, Russia
| | - Takaharu Okajima
- Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Japan
| | - Arvind Raman
- School of Mechanical Engineering, Purdue University, West Lafayette, Indiana, USA. and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana, USA
| |
Collapse
|
21
|
Vakhrusheva A, Endzhievskaya S, Zhuikov V, Nekrasova T, Parshina E, Ovsiannikova N, Popov V, Bagrov D, Minin AА, Sokolova OS. The role of vimentin in directional migration of rat fibroblasts. Cytoskeleton (Hoboken) 2019; 76:467-476. [PMID: 31626376 DOI: 10.1002/cm.21572] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Revised: 10/05/2019] [Accepted: 10/14/2019] [Indexed: 12/16/2022]
Abstract
Cell migration is one of the most important processes in which the cytoskeleton plays a main role. The cytoskeleton network is formed by tubulin microtubules, actin filaments, and intermediate filaments (IFs). While the structure and functions of the two aforementioned proteins have been extensively investigated during the last decades, vimentin IFs structure and their role in cell migration and adhesion remain unclear. Here, we investigated polarity determination in rat fibroblasts with either a knocked out vim gene or with a mutation that blocks filament formation on the stage of unit-length filaments (ULFs). Structured illumination microscopy has demonstrated the difference in the morphology of IFs in wild-type fibroblasts and of ULFs in mutant fibroblasts. We have developed an approach to measure cell stiffness separately on the trailing and leading edges using atomic force microscopy. Young's modulus values on the leading and trailing edge of migrating rat fibroblasts differ approximately by two times, being larger on the leading edge. The knockout of the vim gene leads to having comparable values of Young's moduli on both edges. Vimentin-null cells change the direction of migration more frequently than those expressing wild-type or mutated vimentin. Our results have shown the principle role of vimentin, not only in the form of IFs, but also as ULFs, in the determination of the polarity and the directionality of fibroblast migration.
Collapse
Affiliation(s)
- Anna Vakhrusheva
- Lomonosov Moscow State University, Department of Biology, Moscow, Russia
| | - Sofia Endzhievskaya
- Institute of Protein Research of Russian Academy of Sciences, Department of Cell Biology, Moscow, Russia
| | - Vsevolod Zhuikov
- Research Centre of Biotechnology of Russian Academy of Sciences, Moscow, Russia
| | - Tatyana Nekrasova
- Institute of Protein Research of Russian Academy of Sciences, Department of Cell Biology, Moscow, Russia
| | - Evgenia Parshina
- Lomonosov Moscow State University, Department of Biology, Moscow, Russia
| | - Natalia Ovsiannikova
- Lomonosov Moscow State University, Belozersky Institute of Physico-chemical biology, Moscow, Russia
| | - Vladimir Popov
- Lomonosov Moscow State University, Department of Physics, Moscow, Russia
| | - Dmitry Bagrov
- Lomonosov Moscow State University, Department of Biology, Moscow, Russia
| | - Alexander А Minin
- Institute of Protein Research of Russian Academy of Sciences, Department of Cell Biology, Moscow, Russia
| | - Olga S Sokolova
- Lomonosov Moscow State University, Department of Biology, Moscow, Russia
| |
Collapse
|
22
|
Efremov YM, Shpichka AI, Kotova SL, Timashev PS. Viscoelastic mapping of cells based on fast force volume and PeakForce Tapping. SOFT MATTER 2019; 15:5455-5463. [PMID: 31231747 DOI: 10.1039/c9sm00711c] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Development of fast force volume (FFV), PeakForce Tapping (PFT), and related AFM techniques allow fast acquisition and mapping of a sample's mechanical properties. The methods are well-suited for studying soft biological samples like living cells in a liquid environment. However, the question remains how the measured mechanical properties are related to those acquired with the classical force volume (FV) technique conducted at low indentation rates. The difference is coming mostly from the pronounced viscoelastic behavior of cells, making apparent elastic parameters depending on the probing rate. Here, the viscoelastic analysis was applied directly to the force curves acquired with force volume or PeakForce Tapping by their post-processing based on the Ting's model. Maps from classical force volume, FFV and PFT obtained using special PFT cantilevers and cantilevers modified with microspheres were compared here. With the correct viscoelastic model, which was found to be the power-law rheology model, all the techniques have provided self-consistent results. The techniques were further modified for the mapping of the viscoelastic model-independent complex Young's modulus.
Collapse
Affiliation(s)
- Yu M Efremov
- Institute for Regenerative Medicine, Sechenov University, 8 Trubetskaya St., Moscow, 119991, Russia.
| | - A I Shpichka
- Institute for Regenerative Medicine, Sechenov University, 8 Trubetskaya St., Moscow, 119991, Russia.
| | - S L Kotova
- Institute for Regenerative Medicine, Sechenov University, 8 Trubetskaya St., Moscow, 119991, Russia. and N.N. Semenov Institute of Chemical Physics, 4 Kosygin St., Moscow, 119991, Russia
| | - P S Timashev
- Institute for Regenerative Medicine, Sechenov University, 8 Trubetskaya St., Moscow, 119991, Russia. and N.N. Semenov Institute of Chemical Physics, 4 Kosygin St., Moscow, 119991, Russia and Institute of Photonic Technologies, Research center "Crystallography and Photonics", 2 Pionerskaya St., Troitsk, Moscow 108840, Russia
| |
Collapse
|
23
|
Weber A, Iturri J, Benitez R, Toca-Herrera JL. Measuring biomaterials mechanics with atomic force microscopy. 1. Influence of the loading rate and applied force (pyramidal tips). Microsc Res Tech 2019; 82:1392-1400. [PMID: 31106928 PMCID: PMC6767567 DOI: 10.1002/jemt.23291] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 05/05/2019] [Indexed: 12/03/2022]
Abstract
Atomic force microscopy (AFM) is today an established tool in imaging and determination of mechanical properties of biomaterials. Due to their complex organization, those materials show intricate properties such as viscoelasticity. Therefore, one has to consider that the loading rate at which the sample is probed will lead to different mechanical response (properties). In this work, we studied the dependence of the mechanical properties of endothelial cells on the loading rate using AFM in force spectroscopy mode. We employed a sharp, four‐sided pyramidal indenter and loading rates ranging from 0.5 to 20 μm/s. In addition, by variation of the load (applied forces from 100 to 10,000 pN), the dependence of the cell properties on indentation depth could be determined. We then showed that the mechanical response of endothelial cells depends nonlinearly on the loading rate and follows a weak power‐law. In addition, regions of different viscous response at varying indentation depth could be determined. Based on the results we obtained, a general route map for AFM users for design of cell mechanics experiments was described.
Collapse
Affiliation(s)
- Andreas Weber
- Department of Nanobiotechnology, Institute for Biophysics, University of Natural Resources and Life Sciences, BOKU, Vienna, Austria
| | - Jagoba Iturri
- Department of Nanobiotechnology, Institute for Biophysics, University of Natural Resources and Life Sciences, BOKU, Vienna, Austria
| | - Rafael Benitez
- Department of Mathematics for Economics and Business, Universitat de Valencia, Valencia, Spain
| | - José L Toca-Herrera
- Department of Nanobiotechnology, Institute for Biophysics, University of Natural Resources and Life Sciences, BOKU, Vienna, Austria
| |
Collapse
|
24
|
Rubiano A, Galitz C, Simmons CS. Mechanical Characterization by Mesoscale Indentation: Advantages and Pitfalls for Tissue and Scaffolds. Tissue Eng Part C Methods 2019; 25:619-629. [PMID: 30848168 DOI: 10.1089/ten.tec.2018.0372] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Regenerative medicine and tissue engineering are hindered by the lack of consistent measurements and standards for the mechanical characterization of tissue and scaffolds. Indentation methods for soft matter are favored because of their compatibility with small, arbitrarily shaped samples, but contact mechanics models required to interpret data are often inappropriate for soft, viscous materials. In this study, we demonstrate indentation experiments on a variety of human biopsies, animal tissue, and engineered scaffolds, and we explore the complexities of fitting analytical models to these data. Although objections exist to using Hertz contact models for soft, viscoelastic biological materials since soft matter violates their original assumptions, we demonstrate the experimental conditions that enable consistency and comparability (regardless of arguable misappropriation). Appropriate experimental conditions involving sample hydration, the indentation depth, and the ratio of the probe size to sample thickness enable repeatable metrics that are valuable when comparing synthetic scaffolds and host tissue, and bounds on these parameters are carefully described and discussed. We have also identified a reliable quasistatic parameter that can be derived from indentation data to help researchers compare results across materials and experiments. Although Hertz contact mechanics and linear viscoelastic models may constitute oversimplification for biological materials, the reporting of such simple metrics alongside more complex models is expected to support researchers in tissue engineering and regenerative medicine by providing consistency across efforts to characterize soft matter. Impact Statement To engineer replacement tissue requires a deep understanding of its biomechanical properties. Mesoscale indentation (between micron and millimeter length scales) is well-suited to characterize tissue and engineered replacements as it accommodates small, oddly shaped samples. However, it is easy to run afoul of the assumptions for common contact models when working with biological materials. In this study, we describe experimental procedures and modeling approaches that allow researchers to take advantage of indentation for biomechanical characterization while minimizing its weaknesses.
Collapse
Affiliation(s)
- Andrés Rubiano
- Department of Mechanical and Aerospace Engineering, Herbert Wertheim College of Engineering, Gainesville, Florida
| | - Carly Galitz
- Department of Mathematics, College of Liberal Arts and Sciences, Gainesville, Florida
| | - Chelsey S Simmons
- Department of Mechanical and Aerospace Engineering, Herbert Wertheim College of Engineering, Gainesville, Florida.,J. Crayton Pruitt Family Department of Biomedical Engineering Herbert Wertheim College of Engineering, Gainesville, Florida.,Division of Cardiovascular Medicine, College of Medicine, University of Florida, Gainesville, Florida
| |
Collapse
|
25
|
Böni LJ, Sanchez-Ferrer A, Widmer M, Biviano MD, Mezzenga R, Windhab EJ, Dagastine RR, Fischer P. Structure and Nanomechanics of Dry and Hydrated Intermediate Filament Films and Fibers Produced from Hagfish Slime Fibers. ACS APPLIED MATERIALS & INTERFACES 2018; 10:40460-40473. [PMID: 30371056 DOI: 10.1021/acsami.8b17166] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Intermediate filaments (IFs) are known for their extensibility, flexibility, toughness, and their ability to hydrate. Using keratin-like IFs obtained from slime fibers from the invertebrate Atlantic hagfish ( Myxine glutinosa), films were produced by drop-casting and coagulation on the surface of a MgCl2 buffer. Drop-casting produced self-supporting, smooth, and dense films rich in β-sheets (61%), whereas coagulation formed thin, porous films with a nanorough surface and a lower β-sheet content (51%). The films hydrated and swelled immediately when immersed in water and did not dissolve. X-ray diffraction showed that the β-crystallites remained stable upon hydration, that swelling presumably happens in the amorphous C-terminal tail-domains of the IFs, and that high salt conditions caused a denser network mesh size, suggesting polyelectrolyte behavior. Hydration resulted in a roughly 1000-fold decrease in apparent Young's modulus from 109 to 106 Pa as revealed by atomic force microscopy nanoindentation. Nanoindentation-based power-law rheology and stress-relaxation measurements indicated viscoelasticity and a soft-solid hydrogel character for hydrated films, where roughly 80% of energy is elastically stored and 20% is dissipated. By pulling coagulation films from the buffer interface, macroscopic fibers with highly aligned IF β-crystals similar to natural hagfish fibers were produced. We propose that viscoelasticity and strong hydrogen bonding interactions with the buffer interface are crucial for the production of such long biomimetic fibers with aligned β-sheets. This study demonstrates that hagfish fiber IFs can be reconstituted into functional biomimetic materials that are stiff when dry and retain the ability to hydrate to become soft and viscoelastic when in water.
Collapse
Affiliation(s)
| | | | | | - M D Biviano
- Department of Chemical and Biomolecular Engineering , University of Melbourne , Melbourne 3010 , Australia
| | | | | | - R R Dagastine
- Department of Chemical and Biomolecular Engineering , University of Melbourne , Melbourne 3010 , Australia
| | | |
Collapse
|
26
|
Lai Y, Hu Y. Probing the swelling-dependent mechanical and transport properties of polyacrylamide hydrogels through AFM-based dynamic nanoindentation. SOFT MATTER 2018; 14:2619-2627. [PMID: 29577116 DOI: 10.1039/c7sm02351k] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Hydrogels are composed of a crosslinked polymer network and water. The constitutive behaviors of hydrogels have been modeled based on Flory-Huggins theory. Within this model, the thermodynamic and kinetic parameters are assumed to be of constant values and are typically characterized through swelling tests. Since most hydrogels can absorb a large amount of solvent from the dry state to the swollen state, and the network size and solvent concentration of the hydrogels change significantly, the assumption of constant values of the thermodynamic and kinetic properties as the network swells is questionable. In this work, we have experimentally shown that even for the simple neutral polyacrylamide (PAAm) hydrogels, their mechanical responses cannot be fully described by the Flory-Huggins theory with constant thermodynamic parameters: N (number of chains per unit volume of dry polymers) and χ (polymer-solvent interaction parameter). For a more complete and precise characterization of the hydrogels, we measure the evolving properties of the gels as the network swells. Here, we use dynamic indentation to measure the poroelastic properties (shear modulus G, Poisson's ratio ν and diffusivity D) of the hydrogels under a wide range of swelling ratios. We also use linear perturbation to build the link between G, ν and N, χ, and plot the thermodynamic parameters in the Flory-Huggins theory as a function of the hydrogel swelling ratio. Consequently, the validity of the hydrogel models based on Flory-Huggins theory can be quantitatively examined.
Collapse
Affiliation(s)
- Yang Lai
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
| | | |
Collapse
|
27
|
Rubiano A, Delitto D, Han S, Gerber M, Galitz C, Trevino J, Thomas RM, Hughes SJ, Simmons CS. Viscoelastic properties of human pancreatic tumors and in vitro constructs to mimic mechanical properties. Acta Biomater 2018; 67:331-340. [PMID: 29191507 PMCID: PMC5797706 DOI: 10.1016/j.actbio.2017.11.037] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 11/08/2017] [Accepted: 11/14/2017] [Indexed: 01/18/2023]
Abstract
Pancreatic ductal adenocarcinoma (PDAC) is almost universally fatal, in large part due to a protective fibrotic barrier generated by tumor-associated stromal (TAS) cells. This barrier is thought to promote cancer cell survival and confounds attempts to develop effective therapies. We present a 3D in vitro system that replicates the mechanical properties of the PDAC microenvironment, representing an invaluable tool for understanding the biology of the disease. Mesoscale indentation quantified viscoelastic metrics of resected malignant tumors, inflamed chronic pancreatitis regions, and histologically normal tissue. Both pancreatitis (2.15 ± 0.41 kPa, Mean ± SD) and tumors (5.46 ± 3.18 kPa) exhibit higher Steady-State Modulus (SSM) than normal tissue (1.06 ± 0.25 kPa; p < .005). The average viscosity of pancreatitis samples (63.2 ± 26.7 kPa·s) is significantly lower than that of both normal tissue (252 ± 134 kPa·s) and tumors (349 ± 222 kPa·s; p < .005). To mimic this remodeling behavior, PDAC and TAS cells were isolated from human PDAC tumors. Conditioned medium from PDAC cells was used to culture TAS-embedded collagen hydrogels. After 7 days, TAS-embedded gels in control medium reached SSM (1.45 ± 0.12 kPa) near normal pancreas, while gels maintained with conditioned medium achieved higher SSM (3.38 ± 0.146 kPa) consistent with tumors. Taken together, we have demonstrated an in vitro system that recapitulates in vivo stiffening of PDAC tumors. In addition, our quantification of viscoelastic properties suggests that elastography algorithms incorporating viscosity may be able to more accurately distinguish between pancreatic cancer and pancreatitis. STATEMENT OF SIGNIFICANCE Understanding tumor-stroma crosstalk in pancreatic ductal adenocarcinoma (PDAC) is challenged by a lack of stroma-mimicking model systems. To design appropriate models, pancreatic tissue must be characterized with a method capable of evaluating in vitro models as well. Our indentation-based characterization tool quantified the distinct viscoelastic signatures of inflamed resections from pancreatitis, tumors from PDAC, and otherwise normal tissue to inform development of mechanically appropriate engineered tissues and scaffolds. We also made progress toward a 3D in vitro system that recapitulates mechanical properties of tumors. Our in vitro model of stromal cells in collagen and complementary characterization system can be used to investigate mechanisms of cancer-stroma crosstalk in PDAC and to propose and test innovative therapies.
Collapse
Affiliation(s)
- Andres Rubiano
- Department of Mechanical and Aerospace Engineering, Herbert Wertheim College of Engineering, University of Florida, United States
| | - Daniel Delitto
- Department of Surgery, College of Medicine, University of Florida, United States
| | - Song Han
- Department of Surgery, College of Medicine, University of Florida, United States
| | - Michael Gerber
- Department of Surgery, College of Medicine, University of Florida, United States
| | - Carly Galitz
- Department of Mathematics, College of Liberal Arts and Sciences, University of Florida, United States
| | - Jose Trevino
- Department of Surgery, College of Medicine, University of Florida, United States
| | - Ryan M Thomas
- Department of Surgery, College of Medicine, University of Florida, United States
| | - Steven J Hughes
- Department of Surgery, College of Medicine, University of Florida, United States
| | - Chelsey S Simmons
- Department of Mechanical and Aerospace Engineering, Herbert Wertheim College of Engineering, University of Florida, United States; J. Crayton Pruitt Family Department of Biomedical Engineering, Herbert Wertheim College of Engineering, University of Florida, United States.
| |
Collapse
|
28
|
Efremov YM, Wang WH, Hardy SD, Geahlen RL, Raman A. Measuring nanoscale viscoelastic parameters of cells directly from AFM force-displacement curves. Sci Rep 2017; 7:1541. [PMID: 28484282 PMCID: PMC5431511 DOI: 10.1038/s41598-017-01784-3] [Citation(s) in RCA: 121] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 04/04/2017] [Indexed: 01/12/2023] Open
Abstract
Force-displacement (F-Z) curves are the most commonly used Atomic Force Microscopy (AFM) mode to measure the local, nanoscale elastic properties of soft materials like living cells. Yet a theoretical framework has been lacking that allows the post-processing of F-Z data to extract their viscoelastic constitutive parameters. Here, we propose a new method to extract nanoscale viscoelastic properties of soft samples like living cells and hydrogels directly from conventional AFM F-Z experiments, thereby creating a common platform for the analysis of cell elastic and viscoelastic properties with arbitrary linear constitutive relations. The method based on the elastic-viscoelastic correspondence principle was validated using finite element (FE) simulations and by comparison with the existed AFM techniques on living cells and hydrogels. The method also allows a discrimination of which viscoelastic relaxation model, for example, standard linear solid (SLS) or power-law rheology (PLR), best suits the experimental data. The method was used to extract the viscoelastic properties of benign and cancerous cell lines (NIH 3T3 fibroblasts, NMuMG epithelial, MDA-MB-231 and MCF-7 breast cancer cells). Finally, we studied the changes in viscoelastic properties related to tumorigenesis including TGF-β induced epithelial-to-mesenchymal transition on NMuMG cells and Syk expression induced phenotype changes in MDA-MB-231 cells.
Collapse
Affiliation(s)
- Yuri M Efremov
- School of Mechanical Engineering, Purdue University, West Lafayette, Indiana, 47907, USA.,Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana, 47907, USA
| | - Wen-Horng Wang
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana, 47907, USA
| | - Shana D Hardy
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana, 47907, USA
| | - Robert L Geahlen
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana, 47907, USA.,Purdue University Center for Cancer Research, Purdue University, West Lafayette, Indiana, 47907, USA
| | - Arvind Raman
- School of Mechanical Engineering, Purdue University, West Lafayette, Indiana, 47907, USA. .,Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana, 47907, USA.
| |
Collapse
|
29
|
Bai G, Li Y, Chu HK, Wang K, Tan Q, Xiong J, Sun D. Characterization of biomechanical properties of cells through dielectrophoresis-based cell stretching and actin cytoskeleton modeling. Biomed Eng Online 2017; 16:41. [PMID: 28376803 PMCID: PMC5381122 DOI: 10.1186/s12938-017-0329-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Accepted: 03/16/2017] [Indexed: 02/02/2023] Open
Abstract
Background Cytoskeleton is a highly dynamic network that helps to maintain the rigidity of a cell, and the mechanical properties of a cell are closely related to many cellular functions. This paper presents a new method to probe and
characterize cell mechanical properties through dielectrophoresis (DEP)-based cell stretching manipulation and actin cytoskeleton modeling. Methods Leukemia NB4 cells were used as cell line, and changes in their biological properties were examined after chemotherapy treatment with doxorubicin (DOX). DEP-integrated microfluidic chip was utilized as a low-cost and efficient tool to study the deformability of cells. DEP forces used in cell stretching were first evaluated through computer simulation, and the results were compared with modeling equations and with the results of optical stretching (OT) experiments. Structural parameters were then extracted by fitting the experimental data into the actin cytoskeleton model, and the underlying mechanical properties of the cells were subsequently characterized. Results The DEP forces generated under different voltage inputs were calculated and the results from different approaches demonstrate good approximations to the force estimation. Both DEP and OT stretching experiments confirmed that DOX-treated NB4 cells were stiffer than the untreated cells. The structural parameters extracted from the model and the confocal images indicated significant change in actin network after DOX treatment. Conclusion The proposed DEP method combined with actin cytoskeleton modeling is a simple engineering tool to characterize the mechanical properties of cells.
Collapse
Affiliation(s)
- Guohua Bai
- Key Laboratory of Instrumentation Science and Dynamic Measurement, Ministry of Education, North University of China, Room 418, Building No. 14, No. 3 Xueyuan Road, Taiyuan, 030051, Shanxi, China
| | - Ying Li
- Department of Mechanical and Biomedical Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong, Hong Kong, SAR of China
| | - Henry K Chu
- Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, SAR of China
| | - Kaiqun Wang
- Department of Biomedical Engineering, College of Mechanics, Taiyuan University of Technology, No. 79, West Yingze Street, Taiyuan, 030024, Shanxi, China
| | - Qiulin Tan
- Key Laboratory of Instrumentation Science and Dynamic Measurement, Ministry of Education, North University of China, Room 418, Building No. 14, No. 3 Xueyuan Road, Taiyuan, 030051, Shanxi, China
| | - Jijun Xiong
- Key Laboratory of Instrumentation Science and Dynamic Measurement, Ministry of Education, North University of China, Room 418, Building No. 14, No. 3 Xueyuan Road, Taiyuan, 030051, Shanxi, China
| | - Dong Sun
- Department of Mechanical and Biomedical Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong, Hong Kong, SAR of China.
| |
Collapse
|
30
|
Li Z, Gao S, Brand U, Hiller K, Wollschläger N, Pohlenz F. Note: Nanomechanical characterization of soft materials using a micro-machined nanoforce transducer with an FIB-made pyramidal tip. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:036104. [PMID: 28372387 DOI: 10.1063/1.4977474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The quantitative nanomechanical characterization of soft materials using the nanoindentation tech-nique requires further improvements in the performances of instruments, including their force resolution in particular. A micro-machined silicon nanoforce transducer based upon electrostatic comb drives featuring the force and depth resolutions down to ∼1 nN and 0.2 nm, respectively, is described. At the end of the MEMS transducer's main shaft, a pyramidal tip is fabricated using a focused ion beam facility. A proof-of-principle setup with this MEMS nanoindenter has been established to measure the mechanical properties of soft polydimethylsiloxane. First measurement results demonstrate that the prototype measurement system is able to quantitatively characterize soft materials with elastic moduli down to a few MPa.
Collapse
Affiliation(s)
- Z Li
- Phyikalisch-Technische Bundesanstalt, 38116 Braunschweig, Germany
| | - S Gao
- Phyikalisch-Technische Bundesanstalt, 38116 Braunschweig, Germany
| | - U Brand
- Phyikalisch-Technische Bundesanstalt, 38116 Braunschweig, Germany
| | - K Hiller
- Technische Universität Chemnitz, 09126 Chemnitz, Germany
| | - N Wollschläger
- Bundesanstalt für Materialforschung und -Prüfung, 12205 Berlin, Germany
| | - F Pohlenz
- Phyikalisch-Technische Bundesanstalt, 38116 Braunschweig, Germany
| |
Collapse
|
31
|
Heida T, Neubauer JW, Seuss M, Hauck N, Thiele J, Fery A. Mechanically Defined Microgels by Droplet Microfluidics. MACROMOL CHEM PHYS 2016. [DOI: 10.1002/macp.201600418] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Thomas Heida
- Institute of Physical Chemistry and Polymer Physics; Leibniz-Institut für Polymerforschung Dresden e.V; Hohe Str. 6 01069 Dresden Germany
| | - Jens W. Neubauer
- Institute of Physical Chemistry and Polymer Physics; Leibniz-Institut für Polymerforschung Dresden e.V; Hohe Str. 6 01069 Dresden Germany
| | - Maximilian Seuss
- Institute of Physical Chemistry and Polymer Physics; Leibniz-Institut für Polymerforschung Dresden e.V; Hohe Str. 6 01069 Dresden Germany
| | - Nicolas Hauck
- Institute of Physical Chemistry and Polymer Physics; Leibniz-Institut für Polymerforschung Dresden e.V; Hohe Str. 6 01069 Dresden Germany
- Leibniz Research Cluster (LRC); Leibniz-Institut für Polymerforschung Dresden e.V; Hohe Str. 6 01069 Dresden Germany
| | - Julian Thiele
- Institute of Physical Chemistry and Polymer Physics; Leibniz-Institut für Polymerforschung Dresden e.V; Hohe Str. 6 01069 Dresden Germany
- Leibniz Research Cluster (LRC); Leibniz-Institut für Polymerforschung Dresden e.V; Hohe Str. 6 01069 Dresden Germany
| | - Andreas Fery
- Institute of Physical Chemistry and Polymer Physics; Leibniz-Institut für Polymerforschung Dresden e.V; Hohe Str. 6 01069 Dresden Germany
- Department of Physical Chemistry of Polymeric Materials; Technische Universität Dresden; Hohe Str. 6 01069 Dresden Germany
| |
Collapse
|
32
|
Gavara N. A beginner's guide to atomic force microscopy probing for cell mechanics. Microsc Res Tech 2016; 80:75-84. [PMID: 27676584 PMCID: PMC5217064 DOI: 10.1002/jemt.22776] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 08/17/2016] [Accepted: 08/22/2016] [Indexed: 12/17/2022]
Abstract
Atomic Force microscopy (AFM) is becoming a prevalent tool in cell biology and biomedical studies, especially those focusing on the mechanical properties of cells and tissues. The newest generation of bio-AFMs combine ease of use and seamless integration with live-cell epifluorescence or more advanced optical microscopies. As a unique feature with respect to other bionanotools, AFM provides nanometer-resolution maps for cell topography, stiffness, viscoelasticity, and adhesion, often overlaid with matching optical images of the probed cells. This review is intended for those about to embark in the use of bio-AFMs, and aims to assist them in designing an experiment to measure the mechanical properties of adherent cells. In addition to describing the main steps in a typical cell mechanics protocol and explaining how data is analysed, this review will also discuss some of the relevant contact mechanics models available and how they have been used to characterize specific features of cellular and biological samples. Microsc. Res. Tech. 80:75-84, 2017. © 2016 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Núria Gavara
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London, E1 3NS, UK
| |
Collapse
|
33
|
Cao Z, Dobrynin AV. Contact Mechanics of Nanoparticles: Pulling Rigid Nanoparticles from Soft, Polymeric Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:12520-12529. [PMID: 26509998 DOI: 10.1021/acs.langmuir.5b03222] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Detachment of rigid nanoparticles from soft, gel-like polymeric surfaces is studied by using a combination of the molecular dynamics simulations and theoretical calculations. Simulations show that detachment of nanoparticles from soft surfaces proceeds through a neck formation. Analysis of the simulation results demonstrates that the magnitude of the detachment force f* depends on the nanoparticle radius R(p), shear modulus of substrate G(s), surface tension of substrate γ(s), and work of adhesion W. It is controlled by the balance of the elastic energy, surface energy of the neck, and nanoparticle adhesion energy to a substrate and depends on the dimensionless parameter δ ∝ γ(s)(G(s)R(p))(-1/3)W(-2/3). In the case of small values of the parameter δ ≪ 1, the critical detachment force approaches a critical detachment force calculated by Johnson, Kendall, and Roberts for adhesive contact, f* = 1.5πWR(p). However, in the opposite limit, corresponding to soft substrates, for which δ ≫ 1, the critical detachment force f* ∝ γ(s)(3/2)R(p)(1/2)G(s)(-1/2). All simulation data can be described by a scaling function f* ∝ γ(s)(3/2)R(p)(1/2)G(s)(-1/2)δ(-1.89).
Collapse
Affiliation(s)
- Zhen Cao
- Department of Polymer Science, University of Akron , Akron, Ohio 44325-3909, United States
| | - Andrey V Dobrynin
- Department of Polymer Science, University of Akron , Akron, Ohio 44325-3909, United States
| |
Collapse
|