1
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Esmeraldo Paiva A, Gerlt MS, Läubli NF, Prochukhan N, Baez Vasquez JF, Kaminski Schierle GS, Morris MA. High Aspect Ratio Nanoscale Pores through BCP-Based Metal Oxide Masks and Advanced Dry Etching. ACS Appl Mater Interfaces 2023; 15:57960-57969. [PMID: 37861980 PMCID: PMC10739579 DOI: 10.1021/acsami.3c09863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 09/29/2023] [Accepted: 10/04/2023] [Indexed: 10/21/2023]
Abstract
The reliable and regular modification of the surface properties of substrates plays a crucial role in material research and the development of functional surfaces. A key aspect of this is the development of the surface pores and topographies. These can confer specific advantages such as high surface area as well as specific functions such as hydrophobic properties. Here, we introduce a combination of nanoscale self-assembled block-copolymer-based metal oxide masks with optimized deep reactive ion etching (DRIE) of silicon to permit the fabrication of porous topographies with aspect ratios of up to 50. Following the evaluation of our procedure and involved parameters using various techniques, such as AFM or SEM, the suitability of our features for applications relying on high light absorption as well as efficient thermal management is explored and discussed in further detail.
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Affiliation(s)
- Aislan Esmeraldo Paiva
- AMBER
Research Centre/School of Chemistry, Trinity
College Dublin, Dublin D02 CP49, Ireland
| | - Michael S. Gerlt
- Department
of Biomedical Engineering, Lund University, Lund 22363, Sweden
- Department
of Mechanical and Process Engineering, ETH
Zürich, Zürich 8092, Switzerland
| | - Nino F. Läubli
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, U.K.
| | - Nadezda Prochukhan
- AMBER
Research Centre/School of Chemistry, Trinity
College Dublin, Dublin D02 CP49, Ireland
| | | | | | - Michael A. Morris
- AMBER
Research Centre/School of Chemistry, Trinity
College Dublin, Dublin D02 CP49, Ireland
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2
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Lu M, Christensen CN, Weber JM, Konno T, Läubli NF, Scherer KM, Avezov E, Lio P, Lapkin AA, Kaminski Schierle GS, Kaminski CF. ERnet: a tool for the semantic segmentation and quantitative analysis of endoplasmic reticulum topology. Nat Methods 2023; 20:569-579. [PMID: 36997816 DOI: 10.1038/s41592-023-01815-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 02/10/2023] [Indexed: 04/01/2023]
Abstract
The ability to quantify structural changes of the endoplasmic reticulum (ER) is crucial for understanding the structure and function of this organelle. However, the rapid movement and complex topology of ER networks make this challenging. Here, we construct a state-of-the-art semantic segmentation method that we call ERnet for the automatic classification of sheet and tubular ER domains inside individual cells. Data are skeletonized and represented by connectivity graphs, enabling precise and efficient quantification of network connectivity. ERnet generates metrics on topology and integrity of ER structures and quantifies structural change in response to genetic or metabolic manipulation. We validate ERnet using data obtained by various ER-imaging methods from different cell types as well as ground truth images of synthetic ER structures. ERnet can be deployed in an automatic high-throughput and unbiased fashion and identifies subtle changes in ER phenotypes that may inform on disease progression and response to therapy.
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Affiliation(s)
- Meng Lu
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
- Cambridge Infinitus Research Centre, University of Cambridge, Cambridge, UK
| | - Charles N Christensen
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
- Artificial Intelligence Group, Department of Computer Science and Technology, University of Cambridge, Cambridge, UK
| | - Jana M Weber
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
- Delft Bioinformatics Lab, Intelligent Systems Department, Delft University of Technology, Delft, the Netherlands
| | - Tasuku Konno
- UK Dementia Research Institute at the University of Cambridge and Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Nino F Läubli
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Katharina M Scherer
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Edward Avezov
- UK Dementia Research Institute at the University of Cambridge and Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Pietro Lio
- Artificial Intelligence Group, Department of Computer Science and Technology, University of Cambridge, Cambridge, UK
| | - Alexei A Lapkin
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Gabriele S Kaminski Schierle
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
- Cambridge Infinitus Research Centre, University of Cambridge, Cambridge, UK
| | - Clemens F Kaminski
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK.
- Cambridge Infinitus Research Centre, University of Cambridge, Cambridge, UK.
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3
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Clerc T, Boscq S, Attia R, Kaminski Schierle GS, Charrier B, Läubli NF. Cultivation and Imaging of S. latissima Embryo Monolayered Cell Sheets Inside Microfluidic Devices. Bioengineering (Basel) 2022; 9:bioengineering9110718. [PMID: 36421119 PMCID: PMC9687954 DOI: 10.3390/bioengineering9110718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 11/08/2022] [Accepted: 11/17/2022] [Indexed: 11/23/2022] Open
Abstract
The culturing and investigation of individual marine specimens in lab environments is crucial to further our understanding of this highly complex ecosystem. However, the obtained results and their relevance are often limited by a lack of suitable experimental setups enabling controlled specimen growth in a natural environment while allowing for precise monitoring and in-depth observations. In this work, we explore the viability of a microfluidic device for the investigation of the growth of the alga Saccharina latissima to enable high-resolution imaging by confining the samples, which usually grow in 3D, to a single 2D plane. We evaluate the specimen’s health based on various factors such as its growth rate, cell shape, and major developmental steps with regard to the device’s operating parameters and flow conditions before demonstrating its compatibility with state-of-the-art microscopy imaging technologies such as the skeletonisation of the specimen through calcofluor white-based vital staining of its cell contours as well as the immunolocalisation of the specimen’s cell wall. Furthermore, by making use of the on-chip characterisation capabilities, we investigate the influence of altered environmental illuminations on the embryonic development using blue and red light. Finally, live tracking of fluorescent microspheres deposited on the surface of the embryo permits the quantitative characterisation of growth at various locations of the organism.
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Affiliation(s)
- Thomas Clerc
- Morphogenesis of Macroalgae, Laboratory of Integrative Biology of Marine Models, Station Biologique de Roscoff, CNRS, Sorbonne University, 29680 Roscoff, France
| | - Samuel Boscq
- Morphogenesis of Macroalgae, Laboratory of Integrative Biology of Marine Models, Station Biologique de Roscoff, CNRS, Sorbonne University, 29680 Roscoff, France
| | - Rafaele Attia
- Ecology of Marine Plankton, Laboratory of Adaptation and Diversity in the Marine Environment, Station Biologique de Roscoff, CNRS, Sorbonne University, 29680 Roscoff, France
| | - Gabriele S. Kaminski Schierle
- Molecular Neuroscience Group, Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - Bénédicte Charrier
- Morphogenesis of Macroalgae, Laboratory of Integrative Biology of Marine Models, Station Biologique de Roscoff, CNRS, Sorbonne University, 29680 Roscoff, France
- Correspondence: (B.C.); (N.F.L.)
| | - Nino F. Läubli
- Molecular Neuroscience Group, Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
- Correspondence: (B.C.); (N.F.L.)
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4
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Saikia E, Läubli NF, Vogler H, Rüggeberg M, Herrmann HJ, Burgert I, Burri JT, Nelson BJ, Grossniklaus U, Wittel FK. Correction to: Mechanical factors contributing to the Venus flytrap's rate-dependent response to stimuli. Biomech Model Mechanobiol 2021; 20:2299. [PMID: 34674080 PMCID: PMC8595170 DOI: 10.1007/s10237-021-01522-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Eashan Saikia
- Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, 8093 Zurich, Switzerland
| | - Nino F. Läubli
- Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB3 0AS UK
| | - Hannes Vogler
- Department of Plant and Microbial Biology and Zurich‑Basel Plant Science Center, University of Zurich, 8008 Zurich, Switzerland
| | | | - Hans J. Herrmann
- Laboratoire de Physique et Mécanique des Milieux Hétérogènes, École Supérieur de Physique et de Chimie Industrielles de la Ville de Paris, 75005 Paris, France
| | - Ingo Burgert
- Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, 8093 Zurich, Switzerland
- Swiss Federal Laboratories for Material Science and Technology-EMPA, Cellulose and Wood Materials Laboratory, 8600 Dubendorf, Switzerland
| | - Jan T. Burri
- Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Bradley J. Nelson
- Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Ueli Grossniklaus
- Department of Plant and Microbial Biology and Zurich‑Basel Plant Science Center, University of Zurich, 8008 Zurich, Switzerland
| | - Falk K. Wittel
- Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, 8093 Zurich, Switzerland
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5
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Saikia E, Läubli NF, Vogler H, Rüggeberg M, Herrmann HJ, Burgert I, Burri JT, Nelson BJ, Grossniklaus U, Wittel FK. Mechanical factors contributing to the Venus flytrap's rate-dependent response to stimuli. Biomech Model Mechanobiol 2021; 20:2287-2297. [PMID: 34431032 PMCID: PMC8595191 DOI: 10.1007/s10237-021-01507-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 07/16/2021] [Accepted: 08/13/2021] [Indexed: 11/25/2022]
Abstract
The sensory hairs of the Venus flytrap (Dionaea muscipula Ellis) detect mechanical stimuli imparted by their prey and fire bursts of electrical signals called action potentials (APs). APs are elicited when the hairs are sufficiently stimulated and two consecutive APs can trigger closure of the trap. Earlier experiments have identified thresholds for the relevant stimulus parameters, namely the angular displacement \documentclass[12pt]{minimal}
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\begin{document}$$\omega $$\end{document}ω. However, these experiments could not trace the deformation of the trigger hair’s sensory cells, which are known to transduce the mechanical stimulus. To understand the kinematics at the cellular level, we investigate the role of two relevant mechanical phenomena: viscoelasticity and intercellular fluid transport using a multi-scale numerical model of the sensory hair. We hypothesize that the combined influence of these two phenomena and \documentclass[12pt]{minimal}
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\begin{document}$$\omega $$\end{document}ω contribute to the flytrap’s rate-dependent response to stimuli. In this study, we firstly perform sustained deflection tests on the hair to estimate the viscoelastic material properties of the tissue. Thereafter, through simulations of hair deflection tests at different loading rates, we were able to establish a multi-scale kinematic link between \documentclass[12pt]{minimal}
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\begin{document}$$\delta $$\end{document}δ. Furthermore, we find that the rate at which \documentclass[12pt]{minimal}
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\begin{document}$$\omega $$\end{document}ω. This suggests that mechanosensitive ion channels, expected to be stretch-activated and localized in the plasma membrane of the sensory cells, could be additionally sensitive to the rate at which stretch is applied.
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Affiliation(s)
- Eashan Saikia
- Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, Zurich, 8093, Switzerland.
| | - Nino F Läubli
- Department of Mechanical and Process Engineering, ETH Zurich, Zurich, 8092, Switzerland.,Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, CB3 0AS, United Kingdom
| | - Hannes Vogler
- Department of Plant and Microbial Biology and Zurich-Basel Plant Science Center, University of Zurich, Zurich, 8008, Switzerland
| | | | - Hans J Herrmann
- Laboratoire de Physique et Mécanique des Milieux Hétérogènes, École Supérieur de Physique et de Chimie Industrielles de la Ville de Paris, 75005, Paris, France
| | - Ingo Burgert
- Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, Zurich, 8093, Switzerland.,Swiss Federal Laboratories for Material Science and Technology-EMPA, Cellulose and Wood Materials Laboratory, 8600, Dubendorf, Switzerland
| | - Jan T Burri
- Department of Mechanical and Process Engineering, ETH Zurich, Zurich, 8092, Switzerland
| | - Bradley J Nelson
- Department of Mechanical and Process Engineering, ETH Zurich, Zurich, 8092, Switzerland
| | - Ueli Grossniklaus
- Department of Plant and Microbial Biology and Zurich-Basel Plant Science Center, University of Zurich, Zurich, 8008, Switzerland
| | - Falk K Wittel
- Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, Zurich, 8093, Switzerland
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6
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Läubli NF, Gerlt MS, Wüthrich A, Lewis RTM, Shamsudhin N, Kutay U, Ahmed D, Dual J, Nelson BJ. Embedded Microbubbles for Acoustic Manipulation of Single Cells and Microfluidic Applications. Anal Chem 2021; 93:9760-9770. [PMID: 34228921 PMCID: PMC8295982 DOI: 10.1021/acs.analchem.1c01209] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 06/17/2021] [Indexed: 11/29/2022]
Abstract
Acoustically excited microstructures have demonstrated significant potential for small-scale biomedical applications by overcoming major microfluidic limitations. Recently, the application of oscillating microbubbles has demonstrated their superiority over acoustically excited solid structures due to their enhanced acoustic streaming at low input power. However, their limited temporal stability hinders their direct applicability for industrial or clinical purposes. Here, we introduce the embedded microbubble, a novel acoustofluidic design based on the combination of solid structures (poly(dimethylsiloxane)) and microbubbles (air-filled cavity) to combine the benefits of both approaches while minimizing their drawbacks. We investigate the influence of various design parameters and geometrical features through numerical simulations and experimentally evaluate their manipulation capabilities. Finally, we demonstrate the capabilities of our design for microfluidic applications by investigating its mixing performance as well as through the controlled rotational manipulation of individual HeLa cells.
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Affiliation(s)
- Nino F. Läubli
- Department
of Mechanical and Process Engineering, ETH Zurich, Multi-Scale Robotics Lab, Institute of Robotics and Intelligent Systems, Tannenstrasse 3, 8092 Zurich, Switzerland
- Molecular
Neuroscience Group, Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, CB3 0AS Cambridge, United Kingdom
| | - Michael S. Gerlt
- Department
of Mechanical and Process Engineering, ETH Zurich, Mechanics and Experimental Dynamics, Institute of Mechanical Systems, Tannenstrasse 3, 8092 Zurich, Switzerland
| | - Alexander Wüthrich
- Department
of Mechanical and Process Engineering, ETH Zurich, Multi-Scale Robotics Lab, Institute of Robotics and Intelligent Systems, Tannenstrasse 3, 8092 Zurich, Switzerland
| | - Renard T. M. Lewis
- Department
of Biology, ETH Zurich, Institute of Biochemistry, Otto-Stern-Weg 3, 8093 Zurich, Switzerland
| | - Naveen Shamsudhin
- Department
of Mechanical and Process Engineering, ETH Zurich, Multi-Scale Robotics Lab, Institute of Robotics and Intelligent Systems, Tannenstrasse 3, 8092 Zurich, Switzerland
| | - Ulrike Kutay
- Department
of Biology, ETH Zurich, Institute of Biochemistry, Otto-Stern-Weg 3, 8093 Zurich, Switzerland
| | - Daniel Ahmed
- Department
of Mechanical and Process Engineering, ETH Zurich, Multi-Scale Robotics Lab, Institute of Robotics and Intelligent Systems, Tannenstrasse 3, 8092 Zurich, Switzerland
- Department
of Mechanical and Process Engineering, ETH Zurich, Acoustic Robotics Systems Lab, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | - Jürg Dual
- Department
of Mechanical and Process Engineering, ETH Zurich, Mechanics and Experimental Dynamics, Institute of Mechanical Systems, Tannenstrasse 3, 8092 Zurich, Switzerland
| | - Bradley J. Nelson
- Department
of Mechanical and Process Engineering, ETH Zurich, Multi-Scale Robotics Lab, Institute of Robotics and Intelligent Systems, Tannenstrasse 3, 8092 Zurich, Switzerland
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7
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Gerlt MS, Läubli NF, Manser M, Nelson BJ, Dual J. Reduced Etch Lag and High Aspect Ratios by Deep Reactive Ion Etching (DRIE). Micromachines (Basel) 2021; 12:mi12050542. [PMID: 34068670 PMCID: PMC8150727 DOI: 10.3390/mi12050542] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 05/01/2021] [Accepted: 05/06/2021] [Indexed: 11/16/2022]
Abstract
Deep reactive ion etching (DRIE) with the Bosch process is one of the key procedures used to manufacture micron-sized structures for MEMS and microfluidic applications in silicon and, hence, of increasing importance for miniaturisation in biomedical research. While guaranteeing high aspect ratio structures and providing high design flexibility, the etching procedure suffers from reactive ion etching lag and often relies on complex oxide masks to enable deep etching. The reactive ion etching lag, leading to reduced etch depths for features exceeding an aspect ratio of 1:1, typically causes a height difference of above 10% for structures with aspect ratios ranging from 2.5:1 to 10:1, and, therefore, can significantly influence subsequent device functionality. In this work, we introduce an optimised two-step Bosch process that reduces the etch lag to below 1.5%. Furthermore, we demonstrate an improved three-step Bosch process, allowing the fabrication of structures with 6 μm width at depths up to 180 μm while maintaining their stability.
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Affiliation(s)
- Michael S. Gerlt
- Department of Mechanical and Process Engineering, Institute for Mechanical Systems, 8092 Zurich, Switzerland; (M.M.); (J.D.)
- Correspondence:
| | - Nino F. Läubli
- Department of Mechanical and Process Engineering, Institute of Robotics and Intelligent Systems, 8092 Zurich, Switzerland; (N.F.L.); (B.J.N.)
| | - Michel Manser
- Department of Mechanical and Process Engineering, Institute for Mechanical Systems, 8092 Zurich, Switzerland; (M.M.); (J.D.)
| | - Bradley J. Nelson
- Department of Mechanical and Process Engineering, Institute of Robotics and Intelligent Systems, 8092 Zurich, Switzerland; (N.F.L.); (B.J.N.)
| | - Jürg Dual
- Department of Mechanical and Process Engineering, Institute for Mechanical Systems, 8092 Zurich, Switzerland; (M.M.); (J.D.)
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8
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Läubli NF, Burri JT, Marquard J, Vogler H, Mosca G, Vertti-Quintero N, Shamsudhin N, deMello A, Grossniklaus U, Ahmed D, Nelson BJ. 3D mechanical characterization of single cells and small organisms using acoustic manipulation and force microscopy. Nat Commun 2021; 12:2583. [PMID: 33972516 PMCID: PMC8110787 DOI: 10.1038/s41467-021-22718-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Accepted: 03/22/2021] [Indexed: 12/14/2022] Open
Abstract
Quantitative micromechanical characterization of single cells and multicellular tissues or organisms is of fundamental importance to the study of cellular growth, morphogenesis, and cell-cell interactions. However, due to limited manipulation capabilities at the microscale, systems used for mechanical characterizations struggle to provide complete three-dimensional coverage of individual specimens. Here, we combine an acoustically driven manipulation device with a micro-force sensor to freely rotate biological samples and quantify mechanical properties at multiple regions of interest within a specimen. The versatility of this tool is demonstrated through the analysis of single Lilium longiflorum pollen grains, in combination with numerical simulations, and individual Caenorhabditis elegans nematodes. It reveals local variations in apparent stiffness for single specimens, providing previously inaccessible information and datasets on mechanical properties that serve as the basis for biophysical modelling and allow deeper insights into the biomechanics of these living systems.
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Affiliation(s)
- Nino F Läubli
- Multi-Scale Robotics Lab, ETH Zurich, Zurich, Switzerland
| | - Jan T Burri
- Multi-Scale Robotics Lab, ETH Zurich, Zurich, Switzerland
| | | | - Hannes Vogler
- Department of Plant and Microbial Biology & Zurich-Basel Plant Science Center, University of Zurich, Zurich, Switzerland
| | - Gabriella Mosca
- Department of Plant and Microbial Biology & Zurich-Basel Plant Science Center, University of Zurich, Zurich, Switzerland
| | - Nadia Vertti-Quintero
- Institute for Chemical and Bioengineering, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, Zürich, Switzerland
| | | | - Andrew deMello
- Institute for Chemical and Bioengineering, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, Zürich, Switzerland
| | - Ueli Grossniklaus
- Department of Plant and Microbial Biology & Zurich-Basel Plant Science Center, University of Zurich, Zurich, Switzerland
| | - Daniel Ahmed
- Multi-Scale Robotics Lab, ETH Zurich, Zurich, Switzerland.
- Acoustic Robotics Systems Lab, ETH Zurich, Rüschlikon, Switzerland.
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9
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Burri JT, Vogler H, Läubli NF, Hu C, Grossniklaus U, Nelson BJ. Feeling the force: how pollen tubes deal with obstacles. New Phytol 2018; 220:187-195. [PMID: 29905972 DOI: 10.1111/nph.15260] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 05/08/2018] [Indexed: 05/06/2023]
Abstract
Physical forces are involved in the regulation of plant development and morphogenesis by translating mechanical stress into the modification of physiological processes, which, in turn, can affect cellular growth. Pollen tubes respond rapidly to external stimuli and provide an ideal system to study the effect of mechanical cues at the single-cell level. Here, pollen tubes were exposed to mechanical stress while monitoring the reconfiguration of their growth and recording the generated forces in real-time. We combined a lab-on-a-chip device with a microelectromechanical systems (MEMS)-based capacitive force sensor to mimic and quantify the forces that are involved in pollen tube navigation upon confronting mechanical obstacles. Several stages of obstacle avoidance were identified, including force perception, growth adjustment and penetration. We have experimentally determined the perceptive force threshold, which is the force threshold at which the pollen tube reacts to an obstacle, for Lilium longiflorum and Arabidopsis thaliana. In addition, the method we developed provides a way to calculate turgor pressure based on force and optical data. Pollen tubes sense physical barriers and actively adjust their growth behavior to overcome them. Furthermore, our system offers an ideal platform to investigate intracellular activity during force perception and growth adaption in tip growing cells.
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Affiliation(s)
- Jan T Burri
- Multi-Scale Robotics Laboratory, Department of Mechanical and Process Engineering, ETH Zürich, Zürich, 8092, Switzerland
| | - Hannes Vogler
- Department of Plant and Microbial Biology and Zürich-Basel Plant Science Center, University of Zürich, Zürich, 8008, Switzerland
| | - Nino F Läubli
- Multi-Scale Robotics Laboratory, Department of Mechanical and Process Engineering, ETH Zürich, Zürich, 8092, Switzerland
| | - Chengzhi Hu
- Multi-Scale Robotics Laboratory, Department of Mechanical and Process Engineering, ETH Zürich, Zürich, 8092, Switzerland
| | - Ueli Grossniklaus
- Department of Plant and Microbial Biology and Zürich-Basel Plant Science Center, University of Zürich, Zürich, 8008, Switzerland
| | - Bradley J Nelson
- Multi-Scale Robotics Laboratory, Department of Mechanical and Process Engineering, ETH Zürich, Zürich, 8092, Switzerland
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