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Zhiganshina ER, Arsenyev MV, Chubich DA, Kolymagin DA, Pisarenko AV, Burkatovsky DS, Baranov EV, Vitukhnovsky AG, Lobanov AN, Matital RP, Aleynik DY, Chesnokov SA. Tetramethacrylic benzylidene cyclopentanone dye for one- and two-photon photopolymerization. Eur Polym J 2022. [DOI: 10.1016/j.eurpolymj.2021.110917] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Esteki MH, Malandrino A, Alemrajabi AA, Sheridan GK, Charras G, Moeendarbary E. Poroelastic osmoregulation of living cell volume. iScience 2021; 24:103482. [PMID: 34927026 PMCID: PMC8649806 DOI: 10.1016/j.isci.2021.103482] [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: 01/28/2021] [Revised: 08/19/2021] [Accepted: 11/19/2021] [Indexed: 11/22/2022] Open
Abstract
Cells maintain their volume through fine intracellular osmolarity regulation. Osmotic challenges drive fluid into or out of cells causing swelling or shrinkage, respectively. The dynamics of cell volume changes depending on the rheology of the cellular constituents and on how fast the fluid permeates through the membrane and cytoplasm. We investigated whether and how poroelasticity can describe volume dynamics in response to osmotic shocks. We exposed cells to osmotic perturbations and used defocusing epifluorescence microscopy on membrane-attached fluorescent nanospheres to track volume dynamics with high spatiotemporal resolution. We found that a poroelastic model that considers both geometrical and pressurization rates captures fluid-cytoskeleton interactions, which are rate-limiting factors in controlling volume changes at short timescales. Linking cellular responses to osmotic shocks and cell mechanics through poroelasticity can predict the cell state in health, disease, or in response to novel therapeutics. Cell height changes can be finely captured by defocusing microscopy Water permeation and cellular deformability regulate dynamics of cell volume changes Poroelasticity describes the dynamics of cell volume changes The response of cell to hypo or hyperosmotic shocks are modeled by poroelasticity
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Affiliation(s)
- Mohammad Hadi Esteki
- Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran.,Department of Mechanical Engineering, University College London, London, UK
| | - Andrea Malandrino
- Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Engineering, Universitat Politècnica de Catalunya, Barcelona, Spain
| | - Ali Akbar Alemrajabi
- Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran
| | - Graham K Sheridan
- School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham, UK
| | - Guillaume Charras
- London Centre for Nanotechnology, University College London, London, UK.,Department of Cell and Developmental Biology, University College London, London, UK.,Institute for the Physics of Living Systems, University College London, London, UK
| | - Emad Moeendarbary
- Department of Mechanical Engineering, University College London, London, UK.,Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
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Olson E, Blisko J, Du C, Liu Y, Li Y, Thurber H, Curtzwiler G, Ren J, Thuo M, Yong X, Jiang S. Biobased superhydrophobic coating enabled by nanoparticle assembly. NANOSCALE ADVANCES 2021; 3:4037-4047. [PMID: 36132850 PMCID: PMC9416850 DOI: 10.1039/d1na00296a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 05/08/2021] [Indexed: 06/16/2023]
Abstract
Understanding biobased nanocomposites is critical in fabricating high performing sustainable materials. In this study, fundamental nanoparticle assembly structures at the nanoscale are examined and correlated with the macroscale properties of coatings formulated with these structures. Nanoparticle assembly mechanisms within biobased polymer matrices were probed using in situ liquid-phase atomic force microscopy (AFM) and computational simulation. Furthermore, coatings formulated using these nanoparticle assemblies with biobased polymers were evaluated with regard to the hydrophobicity and adhesion after water immersion. Two biobased glycopolymers, hydroxyethyl cellulose (HEC) and hydroxyethyl starch (HES), were investigated. Their repeating units share the same chemical composition and only differ in monomer conformations (α- and β-anomeric glycosides). Unique fractal structures of silica nanoparticle assemblies were observed with HEC, while compact clusters were observed with HES. Simulation and AFM measurement suggest that strong attraction between silica surfaces in the HEC matrix induces diffusion-limited-aggregation, leading to large-scale, fractal assembly structures. By contrast, weak attraction in HES only produces reaction-limited-aggregation and small compact cluster structures. With high particle loading, the fractal structures in HEC formed a network, which enabled a waterborne formulation of superhydrophobic coating after silane treatment. The silica nanoparticle assembly in HEC was demonstrated to significantly improve adhesion, which showed minimum adhesion loss even after extended water immersion. The superior performance was only observed with HEC, not HES. The results bridge the assembly structures at the nanoscale, influenced by molecular conformation of biobased polymers, to the coating performance at the macroscopic level. Through this study we unveil new opportunities in economical and sustainable development of high-performance biobased materials.
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Affiliation(s)
- Emily Olson
- Department of Materials Science and Engineering, Iowa State University Ames IA 50011 USA
- Polymer and Food Protection Consortium, Iowa State University Ames IA 50011 USA
| | - Jonathan Blisko
- Department of Mechanical Engineering, Binghamton University Binghamton NY 13902 USA
| | - Chuanshen Du
- Department of Materials Science and Engineering, Iowa State University Ames IA 50011 USA
| | - Yi Liu
- Department of Mechanical Engineering, Iowa State University Ames IA 50011 USA
| | - Yifan Li
- Department of Materials Science and Engineering, Iowa State University Ames IA 50011 USA
| | - Henry Thurber
- Department of Materials Science and Engineering, Iowa State University Ames IA 50011 USA
- Polymer and Food Protection Consortium, Iowa State University Ames IA 50011 USA
| | - Greg Curtzwiler
- Polymer and Food Protection Consortium, Iowa State University Ames IA 50011 USA
- Department of Food Science and Human Nutrition, Iowa State University Ames IA 50011 USA
| | - Juan Ren
- Department of Mechanical Engineering, Iowa State University Ames IA 50011 USA
| | - Martin Thuo
- Department of Materials Science and Engineering, Iowa State University Ames IA 50011 USA
| | - Xin Yong
- Department of Mechanical Engineering, Binghamton University Binghamton NY 13902 USA
| | - Shan Jiang
- Department of Materials Science and Engineering, Iowa State University Ames IA 50011 USA
- Polymer and Food Protection Consortium, Iowa State University Ames IA 50011 USA
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The expression and regulation of Wnt1 in tooth movement-initiated mechanotransduction. Am J Orthod Dentofacial Orthop 2020; 158:e151-e160. [PMID: 33139146 DOI: 10.1016/j.ajodo.2020.08.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2020] [Revised: 08/01/2020] [Accepted: 08/01/2020] [Indexed: 12/20/2022]
Abstract
INTRODUCTION The Wnt signaling pathway acts as a key regulator of skeletal development and its homeostasis. However, the potential role of Wnt1 in the mechanotransduction machinery of orthodontic tooth movement-initiated bone remodeling is still unclear. Hence, this study focused on the regulatory dynamics of the Wnt1 expression in both the periodontal ligament (PDL) and osteocytes in vivo and in vitro. METHODS The Wnt1 expression in the orthodontically moved maxillary first molar in mice was assessed at 0, 1, and 5 days, on both the compression and tension sides. Primary isolated human PDL (hPDL) fibroblasts, as well as murine long-bone osteocyte-Y4 (MLO-Y4) cells, were exposed to continuous compressive force and static tensile force. RESULTS The relative quantification of immunodetection showed that orthodontic tooth movement significantly stimulated the Wnt1 expression in both the PDL and alveolar osteocytes on the tension side on day 5, whereas the expression on the compression side did not change. This increase in the Wnt1 expression, shown in vivo, was also noted after the application of 12% static tensile force in isolated hPDL fibroblasts and 20% in MLO-Y4 cells. In contrast, a compressive force led to the attenuation of the Wnt1 gene expression in both hPDL fibroblasts and MLO-Y4 cells in a force-dependent manner. In the osteocyte-PDL coculture system, recombinant sclerostin attenuated Wnt1 in PDL, whereas the antisclerostin antibody upregulated its gene expression, indicating that mechanically-driven Wnt1 signaling in PDL might be regulated by osteocytic sclerostin. CONCLUSIONS Our findings provide that Wnt1 signaling plays a vital role in tooth movement-initiated bone remodeling via innovative mechanotransduction approaches.
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Rong N, Zhang M, Wang Y, Wu H, Qi H, Fu X, Li D, Yang C, Wang Y, Fan Z. Effects of extracellular matrix rigidity on sonoporation facilitated by targeted microbubbles: Bubble attachment, bubble dynamics, and cell membrane permeabilization. ULTRASONICS SONOCHEMISTRY 2020; 67:105125. [PMID: 32298974 DOI: 10.1016/j.ultsonch.2020.105125] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 02/19/2020] [Accepted: 04/07/2020] [Indexed: 06/11/2023]
Abstract
In this study, we investigated the effects of extracellular matrix rigidity, an important physical property of microenvironments regulating cell morphology and functions, on sonoporation facilitated by targeted microbubbles, highlighting the role of microbubbles. We conducted mechanistic studies at the cellular level on physiologically relevant soft and rigid substrates. By developing a unique imaging strategy, we first resolved details of the 3D attachment configurations between targeted microbubbles and cell membrane. High-speed video microscopy then unveiled bubble dynamics driven by a single ultrasound pulse. Finally, we evaluated the cell membrane permeabilization using a small molecule model drug. Our results demonstrate that: (1) stronger targeted microbubble attachment was formed for cells cultured on the rigid substrate, while six different attachment configurations were revealed in total; (2) more violent bubble oscillation was observed for cells cultured on the rigid substrate, while one third of bubbles attached to cells on the soft substrate exhibited deformation shortly after ultrasound was turned off; (3) higher acoustic pressure was needed to permeabilize the cell membrane for cells on the soft substrate, while under the same ultrasound condition, acoustically-activated microbubbles generated larger pores as compared to cells cultured on the soft substrate. The current findings provide new insights to understand the underlying mechanisms of sonoporation in a physiologically relevant context and may be useful for the clinical translation of sonoporation.
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Affiliation(s)
- Ning Rong
- Department of Biomedical Engineering, School of Precision Instruments and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China
| | - Meiru Zhang
- Department of Biomedical Engineering, School of Precision Instruments and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China
| | - Yulin Wang
- Department of Biomedical Engineering, School of Precision Instruments and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China
| | - Hao Wu
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China
| | - Hui Qi
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China
| | - Xing Fu
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China
| | - Dachao Li
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China
| | - Chunmei Yang
- Department of Biomedical Engineering, School of Precision Instruments and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China
| | - Yan Wang
- Department of Biomedical Engineering, School of Precision Instruments and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China
| | - Zhenzhen Fan
- Department of Biomedical Engineering, School of Precision Instruments and Opto-Electronics Engineering, Tianjin University, Tianjin 300072, China; State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China.
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Esteki MH, Alemrajabi AA, Hall CM, Sheridan GK, Azadi M, Moeendarbary E. A new framework for characterization of poroelastic materials using indentation. Acta Biomater 2020; 102:138-148. [PMID: 31715334 PMCID: PMC6958526 DOI: 10.1016/j.actbio.2019.11.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 11/03/2019] [Accepted: 11/06/2019] [Indexed: 01/07/2023]
Abstract
To characterize a poroelastic material, typically an indenter is pressed onto the surface of the material with a ramp of a finite approach velocity followed by a hold where the indenter displacement is kept constant. This leads to deformation of the porous matrix, pressurization of the interstitial fluid and relaxation due to redistribution of fluid through the pores. In most studies the poroelastic properties, including elastic modulus, Poisson ratio and poroelastic diffusion coefficient, are extracted by assuming an instantaneous step indentation. However, exerting step like indentation is not experimentally possible and usually a ramp indentation with a finite approach velocity is applied. Moreover, the poroelastic relaxation time highly depends on the approach velocity in addition to the poroelastic diffusion coefficient and the contact area. Here, we extensively studied the effect of indentation velocity using finite element simulations which has enabled the formulation of a new framework based on a master curve that incorporates the finite rise time. To verify our novel framework, the poroelastic properties of two types of hydrogels were extracted experimentally using indentation tests at both macro and micro scales. Our new framework that is based on consideration of finite approach velocity is experimentally easy to implement and provides a more accurate estimation of poroelastic properties. STATEMENT OF SIGNIFICANCE: Hydrogels, tissues and living cells are constituted of a sponge-like porous elastic matrix bathed in an interstitial fluid. It has been shown that these materials behave according to the theory of 'poroelasticity' when mechanically stimulated in a way similar to that experienced in organs within the body. In this theory, the rate at which the fluid-filled sponge can be deformed is limited by how fast interstitial fluid can redistribute within the sponge in response to deformation. Here, we simulated indentation experiments at different rates and formulated a new framework that inherently captures the effects of stimulation speed on the mechanical response of poroelastic materials. We validated our framework by conducting experiments at different length-scales on agarose and polyacrylamide hydrogels.
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Affiliation(s)
- Mohammad Hadi Esteki
- Department of Mechanical Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran; Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Ali Akbar Alemrajabi
- Department of Mechanical Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran
| | - Chloe M Hall
- Department of Mechanical Engineering, University College London, London, United Kingdom; School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, United Kingdom
| | - Graham K Sheridan
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Mojtaba Azadi
- School of Engineering, College of Science and Engineering, San Francisco State University, San Francisco, CA 94132, United States; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Emad Moeendarbary
- Department of Mechanical Engineering, University College London, London, United Kingdom; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States.
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Effect of F-actin and Microtubules on Cellular Mechanical Behavior Studied Using Atomic Force Microscope and an Image Recognition-Based Cytoskeleton Quantification Approach. Int J Mol Sci 2020; 21:ijms21020392. [PMID: 31936268 PMCID: PMC7014474 DOI: 10.3390/ijms21020392] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 01/02/2020] [Accepted: 01/03/2020] [Indexed: 11/16/2022] Open
Abstract
Cytoskeleton morphology plays a key role in regulating cell mechanics. Particularly, cellular mechanical properties are directly regulated by the highly cross-linked and dynamic cytoskeletal structure of F-actin and microtubules presented in the cytoplasm. Although great efforts have been devoted to investigating the qualitative relation between the cellular cytoskeleton state and cell mechanical properties, comprehensive quantification results of how the states of F-actin and microtubules affect mechanical behavior are still lacking. In this study, the effect of both F-actin and microtubules morphology on cellular mechanical properties was quantified using atomic force microscope indentation experiments together with the proposed image recognition-based cytoskeleton quantification approach. Young’s modulus and diffusion coefficient of NIH/3T3 cells with different cytoskeleton states were quantified at different length scales. It was found that the living NIH/3T3 cells sense and adapt to the F-actin and microtubules states: both the cellular elasticity and poroelasticity are closely correlated to the depolymerization degree of F-actin and microtubules at all measured indentation depths. Moreover, the significance of the quantitative effects of F-actin and microtubules in affecting cellular mechanical behavior is depth-dependent.
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Abstract
Physical stimuli are essential for the function of eukaryotic cells, and changes in physical signals are important elements in normal tissue development as well as in disease initiation and progression. The complexity of physical stimuli and the cellular signals they initiate are as complex as those triggered by chemical signals. One of the most important, and the focus of this review, is the effect of substrate mechanical properties on cell structure and function. The past decade has produced a nearly exponentially increasing number of mechanobiological studies to define how substrate stiffness alters cell biology using both purified systems and intact tissues. Here we attempt to identify common features of mechanosensing in different systems while also highlighting the numerous informative exceptions to what in early studies appeared to be simple rules by which cells respond to mechanical stresses.
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Affiliation(s)
- Paul A Janmey
- Department of Physiology, Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Bioengineering, University of California-Berkeley, Berkeley, California; and Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
| | - Daniel A Fletcher
- Department of Physiology, Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Bioengineering, University of California-Berkeley, Berkeley, California; and Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
| | - Cynthia A Reinhart-King
- Department of Physiology, Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Bioengineering, University of California-Berkeley, Berkeley, California; and Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee
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Skamrahl M, Colin-York H, Barbieri L, Fritzsche M. Simultaneous Quantification of the Interplay Between Molecular Turnover and Cell Mechanics by AFM-FRAP. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1902202. [PMID: 31419037 PMCID: PMC7612032 DOI: 10.1002/smll.201902202] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 07/22/2019] [Indexed: 06/02/2023]
Abstract
Quantifying the adaptive mechanical behavior of living cells is essential for the understanding of their inner working and function. Yet, despite the establishment of quantitative methodologies correlating independent measurements of cell mechanics and its underlying molecular kinetics, explicit evidence and knowledge of the sensitivity of the feedback mechanisms of cells controlling their adaptive mechanics behavior remains elusive. Here, a combination of atomic force microscopy and fluorescence recovery after photobleaching is introduced offering simultaneous quantification and direct correlation of molecule kinetics and mechanics in living cells. Systematic application of this optomechanical atomic force microscopy-fluorescence recovery after photobleaching platform reveals changes in the actin turnover and filament lengths of ventral actin stress fibers in response to constant mechanical force at the apical actin cortex with a dynamic range from 0.1 to 10 nN, highlighting a direct relationship of active mechanosensation and adaptation of the cellular actin cytoskeleton. Simultaneous quantification of the relationship between molecule kinetics and cell mechanics may thus open-up unprecedented insights into adaptive mechanobiological mechanisms of cells.
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Affiliation(s)
- Mark Skamrahl
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, Oxford. OX3 9DS, United Kingdom
| | - Huw Colin-York
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, Oxford. OX3 9DS, United Kingdom
| | - Liliana Barbieri
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, Oxford. OX3 9DS, United Kingdom
| | - Marco Fritzsche
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, Oxford. OX3 9DS, United Kingdom
- Kennedy Institute for Rheumatology, Roosevelt Drive, University of Oxford, Oxford, OX3 7LF, United Kingdom
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Yadav S, Gulec S, Tadmor R, Lian I. A Novel Technique Enables Quantifying the Molecular Interaction of Solvents with Biological Tissues. Sci Rep 2019; 9:9319. [PMID: 31249358 PMCID: PMC6597696 DOI: 10.1038/s41598-019-45637-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Accepted: 06/05/2019] [Indexed: 11/27/2022] Open
Abstract
The pharmaceutical industry uses various solvents to increase drug penetrability to tissues. The solvent’s choice affects the efficacy of a drug. In this paper, we provide an unprecedented means of relating a solvent to a tissue quantitatively. We show that the solvents induce reorientation of the tissue surface molecules in a way that favors interaction and, therefore, penetrability of a solvent to a tissue. We provide, for the first time, a number for this tendency through a new physical property termed Interfacial Modulus (Gs). Gs, which so far was only predicted theoretically, is inversely proportional to such interactions. As model systems, we use HeLa and HaCaT tissue cultures with water and with an aqueous DMSO solution. The measurements are done using Centrifugal Adhesion Balance (CAB) when set to effective zero gravity. As expected, the addition of DMSO to water reduces Gs. This reduction in Gs is usually higher for HaCaT than for HeLa cells, which agrees with the common usage of DMSO in dermal medicine. We also varied the rigidities of the tissues. The tissue rigidity is not expected to relate to Gs, and indeed our results didn’t show a correlation between these two physical properties.
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Affiliation(s)
- Sakshi Yadav
- Dan F. Smith Department of Chemical Engineering, Lamar University, Beaumont, TX, 77710, USA
| | - Semih Gulec
- Dan F. Smith Department of Chemical Engineering, Lamar University, Beaumont, TX, 77710, USA
| | - Rafael Tadmor
- Dan F. Smith Department of Chemical Engineering, Lamar University, Beaumont, TX, 77710, USA. .,Department of Mechanical Engineering, Ben-Gurion University of the Negev, Beer-Sheva, 8410501, Israel.
| | - Ian Lian
- Department of Biology, Lamar University, Beaumont, TX, 77710, USA
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Gulec S, Yadav S, Das R, Bhave V, Tadmor R. The Influence of Gravity on Contact Angle and Circumference of Sessile and Pendant Drops has a Crucial Historic Aspect. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:5435-5441. [PMID: 30839217 DOI: 10.1021/acs.langmuir.8b03861] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Normally, pendant drops adapt contact angles that are closer to 90° than their sessile analogues. This is due to the drop's weight that pulls the pendant drop and straightens its contact angles. In this paper, we show a case in which the opposite happens: sessile drops that adapt contact angles that are closer to 90° than their pendant analogues. To achieve these peculiar states, one needs to increase the effective gravity on the drops and then relax it again to 1 g. Apparently, this and other phenomena depend not only on the direction of the gravitational force but also on the drop's history. We show that the drop's contact angle (and resultant area) is affected by two types of histories: short-term history and long-term history. For example, if we gradually increase the effective gravity on the drop, decrease it back to 1 g, and then repeat this cycle again and again, we see that the first cycle is drastically different, whereas other cycles approach a plateau in their behavior. In addition to drop's history, we explain these observations in terms of volume conservation, drop contact area, and pinning effect. This study may be generalized for other body forces such as electrical and magnetic or accelerating systems.
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Affiliation(s)
- Semih Gulec
- Dan F. Smith Department of Chemical Engineering , Lamar University , Beaumont , Texas 77710 , United States
| | - Sakshi Yadav
- Dan F. Smith Department of Chemical Engineering , Lamar University , Beaumont , Texas 77710 , United States
| | - Ratul Das
- Dan F. Smith Department of Chemical Engineering , Lamar University , Beaumont , Texas 77710 , United States
| | - Vaibhav Bhave
- Dan F. Smith Department of Chemical Engineering , Lamar University , Beaumont , Texas 77710 , United States
| | - Rafael Tadmor
- Dan F. Smith Department of Chemical Engineering , Lamar University , Beaumont , Texas 77710 , United States
- Department of Mechanical Engineering , Ben Gurion University , Beer Sheva 8410501 , Israel
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Abstract
Quantification of the actin cytoskeleton is of prime importance to unveil the cellular force sensing and transduction mechanism. Although fluorescence imaging provides a convenient tool for observing the morphology of the actin cytoskeleton, due to the lack of approaches to accurate actin cytoskeleton quantification, the dynamics of mechanotransduction is still poorly understood. Currently, the existing image-based actin cytoskeleton analysis tools are either incapable of quantifying both the orientation and the quantity of the actin cytoskeleton simultaneously or the quantified results are subject to analysis artifacts. In this study, we propose an image recognition-based actin cytoskeleton quantification (IRAQ) approach, which quantifies both the actin cytoskeleton orientation and quantity by using edge, line, and brightness detection algorithms. The actin cytoskeleton is quantified through three parameters: the partial actin-cytoskeletal deviation (PAD), the total actin-cytoskeletal deviation (TAD), and the average actin-cytoskeletal intensity (AAI). First, Canny and Sobel edge detectors are applied to skeletonize the actin cytoskeleton images, then PAD and TAD are quantified using the line directions detected by Hough transform, and AAI is calculated through the summational brightness over the detected cell area. To verify the quantification accuracy, the proposed IRAQ was applied to six artificially-generated actin cytoskeleton mesh work models. The average error for both the quantified PAD and TAD was less than 1.22 ∘ . Then, IRAQ was implemented to quantify the actin cytoskeleton of NIH/3T3 cells treated with an F-actin inhibitor (latrunculin B). The quantification results suggest that the local and total actin-cytoskeletal organization became more disordered with the increase of latrunculin B dosage, and the quantity of the actin cytoskeleton showed a monotonically decreasing relation with latrunculin B dosage.
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