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Nicholls D, Kobylynska M, Broad Z, Wells J, Robinson A, McGrouther D, Moshtaghpour A, Kirkland AI, Fleck RA, Browning ND. The Potential of Subsampling and Inpainting for Fast Low-Dose Cryo FIB-SEM Imaging. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2024; 30:96-102. [PMID: 38321738 DOI: 10.1093/micmic/ozae005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 12/13/2023] [Accepted: 01/06/2024] [Indexed: 02/08/2024]
Abstract
Traditional image acquisition for cryo focused ion-beam scanning electron microscopy (FIB-SEM) tomography often sees thousands of images being captured over a period of many hours, with immense data sets being produced. When imaging beam sensitive materials, these images are often compromised by additional constraints related to beam damage and the devitrification of the material during imaging, which renders data acquisition both costly and unreliable. Subsampling and inpainting are proposed as solutions for both of these aspects, allowing fast and low-dose imaging to take place in the Focused ion-beam scanning electron microscopy FIB-SEM without an appreciable loss in image quality. In this work, experimental data are presented which validate subsampling and inpainting as a useful tool for convenient and reliable data acquisition in a FIB-SEM, with new methods of handling three-dimensional data being employed in the context of dictionary learning and inpainting algorithms using a newly developed microscope control software and data recovery algorithm.
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Affiliation(s)
- Daniel Nicholls
- Department of Mechanical, Materials and Aerospace Engineering, University of Liverpool, Liverpool, L69 3BX, UK
- SenseAI Innovations Ltd., Liverpool, L69 3BX, UK
| | - Maryna Kobylynska
- Centre for Ultrastructural Imaging, King's College London, London, WC2R 2LS, UK
- Randall Centre for Cell and Molecular Biophysics, King's College London, London, WC2R 2LS, UK
| | - Zoë Broad
- Department of Mechanical, Materials and Aerospace Engineering, University of Liverpool, Liverpool, L69 3BX, UK
| | - Jack Wells
- Distributed Algorithms Centre for Doctoral Training, University of Liverpool, Liverpool, L69 3BX, UK
| | - Alex Robinson
- Department of Mechanical, Materials and Aerospace Engineering, University of Liverpool, Liverpool, L69 3BX, UK
- SenseAI Innovations Ltd., Liverpool, L69 3BX, UK
| | | | - Amirafshar Moshtaghpour
- Department of Mechanical, Materials and Aerospace Engineering, University of Liverpool, Liverpool, L69 3BX, UK
- Correlated Imaging Group, Rosalind Franklin Institute, Didcot, OX11 0QS, UK
| | - Angus I Kirkland
- Correlated Imaging Group, Rosalind Franklin Institute, Didcot, OX11 0QS, UK
- Department of Materials, University of Oxford, Oxford, OX2 6NN, UK
| | - Roland A Fleck
- Centre for Ultrastructural Imaging, King's College London, London, WC2R 2LS, UK
- Randall Centre for Cell and Molecular Biophysics, King's College London, London, WC2R 2LS, UK
| | - Nigel D Browning
- Department of Mechanical, Materials and Aerospace Engineering, University of Liverpool, Liverpool, L69 3BX, UK
- SenseAI Innovations Ltd., Liverpool, L69 3BX, UK
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2
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Verwee E, Van de Walle D, De Bruyne M, Mienis E, Sekulic M, Chaerle P, Vyverman W, Foubert I, Dewettinck K. Visualisation of microalgal lipid bodies through electron microscopy. J Microsc 2024; 293:118-131. [PMID: 38149687 DOI: 10.1111/jmi.13259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 12/20/2023] [Accepted: 12/22/2023] [Indexed: 12/28/2023]
Abstract
In this study, transmission electron microscopy (TEM) and cryo-scanning electron microscopy (cryo-SEM) were evaluated for their ability to detect lipid bodies in microalgae. To do so, Phaeodactylum tricornutum and Nannochloropsis oculata cells were harvested in both the mid-exponential and early stationary growth phase. Two different cryo-SEM cutting methods were compared: cryo-planing and freeze-fracturing. The results showed that, despite the longer preparation time, TEM visualisation preceded by cryo-immobilisation allows a clear detection of lipid bodies and is preferable to cryo-SEM. Using freeze-fracturing, lipid bodies were rarely detected. This was only feasible if crystalline layers in the internal structure, most likely related to sterol esters or di-saturated triacylglycerols, were revealed. Furthermore, lipid bodies could not be detected using cryo-planing. Cryo-SEM is also not the preferred technique to recognise other organelles besides lipid bodies, yet it did reveal chloroplasts in both species and filament-containing organelles in cryo-planed Nannochloropsis oculata samples.
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Affiliation(s)
- Ellen Verwee
- Department of Food Technology, Food Structure & Function research group, Safety and Health, Ghent University, Ghent, Belgium
- Department of Biotechnology, Ghent University, Ghent, Belgium
| | - Davy Van de Walle
- Department of Food Technology, Food Structure & Function research group, Safety and Health, Ghent University, Ghent, Belgium
| | - Michiel De Bruyne
- VIB BioImaging Core VIB, Ghent, Belgium
- VIB Center for Inflammation Research VIB, Ghent, Belgium
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Esther Mienis
- Research Unit Food & Lipids, KU Leuven Kulak, Kortrijk, Belgium
- Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Leuven, Belgium
| | - Mirna Sekulic
- Department of Biology, Laboratory of Protistology and Aquatic Ecology, Ghent University, Ghent, Belgium
- VIB Center for Plant Systems Biology VIB, Ghent, Belgium
| | - Peter Chaerle
- Department of Biology, Laboratory of Protistology and Aquatic Ecology, Ghent University, Ghent, Belgium
- Department of Biology, BCCM/DCG Diatoms Collection, Ghent University, Ghent, Belgium
| | - Wim Vyverman
- Department of Biology, Laboratory of Protistology and Aquatic Ecology, Ghent University, Ghent, Belgium
| | - Imogen Foubert
- Research Unit Food & Lipids, KU Leuven Kulak, Kortrijk, Belgium
- Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Leuven, Belgium
| | - Koen Dewettinck
- Department of Food Technology, Food Structure & Function research group, Safety and Health, Ghent University, Ghent, Belgium
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3
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Woods EV, Kim SH, El-Zoka AA, Stephenson LT, Gault B. Scalable substrate development for aqueous sample preparation for atom probe tomography. J Microsc 2023. [PMID: 38115688 DOI: 10.1111/jmi.13255] [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: 07/13/2023] [Revised: 11/13/2023] [Accepted: 12/15/2023] [Indexed: 12/21/2023]
Abstract
Reliable and consistent preparation of atom probe tomography (APT) specimens from aqueous and hydrated biological specimens remains a significant challenge. One particularly difficult process step is the use of a focused ion beam (FIB) instrument for preparing the required needle-shaped specimen, typically involving a 'lift-out' procedure of a small sample of material. Here, two alternative substrate designs are introduced that enable using FIB only for sharpening, along with example APT datasets. The first design is a laser-cut FIB-style half-grid close to those used for transmission electron microscopy (TEM) that can be used in a grid holder compatible with APT pucks. The second design is a larger, standalone self-supporting substrate called a 'crown', with several specimen positions, which self-aligns in APT pucks, prepared by electrical discharge machining (EDM). Both designs are made nanoporous, to provide strength to the liquid-substrate interface, using chemical and vacuum dealloying. Alpha brass, a simple, widely available, lower-cost alternative to previously proposed substrates, was selected for this work. The resulting designs and APT data are presented and suggestions are provided to help drive wider community adoption.
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Affiliation(s)
- Eric V Woods
- Department Mikrostrukturphysik und Legierungsdesign, Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany
| | - Se-Ho Kim
- Department Mikrostrukturphysik und Legierungsdesign, Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany
- Department of Materials Science and Engineering, Korea University, Seoul, Republic of Korea
| | - Ayman A El-Zoka
- Department Mikrostrukturphysik und Legierungsdesign, Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany
- Department of Materials, Royal School of Mines, Imperial College London, London, UK
| | - L T Stephenson
- Department Mikrostrukturphysik und Legierungsdesign, Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany
- Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, New South Wales, Australia
| | - B Gault
- Department Mikrostrukturphysik und Legierungsdesign, Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany
- Department of Materials, Royal School of Mines, Imperial College London, London, UK
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4
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Rey M, Kolker J, Richards JA, Malhotra I, Glen TS, Li NYD, Laidlaw FHJ, Renggli D, Vermant J, Schofield AB, Fujii S, Löwen H, Clegg PS. Interactions between interfaces dictate stimuli-responsive emulsion behaviour. Nat Commun 2023; 14:6723. [PMID: 37872193 PMCID: PMC10593850 DOI: 10.1038/s41467-023-42379-z] [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: 11/07/2022] [Accepted: 10/10/2023] [Indexed: 10/25/2023] Open
Abstract
Stimuli-responsive emulsions offer a dual advantage, combining long-term storage with controlled release triggered by external cues such as pH or temperature changes. This study establishes that thermo-responsive emulsion behaviour is primarily determined by interactions between, rather than within, interfaces. Consequently, the stability of these emulsions is intricately tied to the nature of the stabilizing microgel particles - whether they are more polymeric or colloidal, and the morphology they assume at the liquid interface. The colloidal properties of the microgels provide the foundation for the long-term stability of Pickering emulsions. However, limited deformability can lead to non-responsive emulsions. Conversely, the polymeric properties of the microgels enable them to spread and flatten at the liquid interface, enabling stimuli-responsive behaviour. Furthermore, microgels shared between two emulsion droplets in flocculated emulsions facilitate stimuli-responsiveness, regardless of their internal architecture. This underscores the pivotal role of microgel morphology and the forces they exert on liquid interfaces in the control and design of stimuli-responsive emulsions and interfaces.
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Affiliation(s)
- Marcel Rey
- School of Physics and Astronomy, The University of Edinburgh, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, UK.
- Department of Physics, University of Gothenburg, SE-41296, Gothenburg, Sweden.
| | - Jannis Kolker
- Institute for Theoretical Physics II: Soft Matter, Heinrich-Heine University Düsseldorf, D-40225, Düsseldorf, Germany
| | - James A Richards
- School of Physics and Astronomy, The University of Edinburgh, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, UK
| | - Isha Malhotra
- Institute for Theoretical Physics II: Soft Matter, Heinrich-Heine University Düsseldorf, D-40225, Düsseldorf, Germany
| | - Thomas S Glen
- School of Physics and Astronomy, The University of Edinburgh, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, UK
| | - N Y Denise Li
- School of Physics and Astronomy, The University of Edinburgh, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, UK
| | - Fraser H J Laidlaw
- School of Physics and Astronomy, The University of Edinburgh, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, UK
| | - Damian Renggli
- Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093, Zürich, Switzerland
| | - Jan Vermant
- Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093, Zürich, Switzerland
| | - Andrew B Schofield
- School of Physics and Astronomy, The University of Edinburgh, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, UK
| | - Syuji Fujii
- Department of Applied Chemistry, Faculty of Engineering, Osaka Institute of Technology, 5-16-1 Omiya, Asahi-ku, Osaka, 535-8585, Japan
- Nanomaterials Microdevices Research Center, Osaka Institute of Technology, 5-16-1 Omiya, Asahi-ku, Osaka, 535-8585, Japan
| | - Hartmut Löwen
- Institute for Theoretical Physics II: Soft Matter, Heinrich-Heine University Düsseldorf, D-40225, Düsseldorf, Germany
| | - Paul S Clegg
- School of Physics and Astronomy, The University of Edinburgh, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, UK
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5
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Cho JY, Grabovac E, Wagner A, Gumfekar SP, Vick D, Price P, Makeiff D, Kulka M. Cryo-Scanning Electron Microscopy Analysis for the Structural Evolution of Cellulose Nanocrystals based Hydrogels. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2023; 29:660-661. [PMID: 37613420 DOI: 10.1093/micmic/ozad067.324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Affiliation(s)
- Jae-Young Cho
- National Research Council of CANADA - Nanotechnology Research Centre, Edmonton, Alberta, Canada
| | - Emily Grabovac
- National Research Council of CANADA - Nanotechnology Research Centre, Edmonton, Alberta, Canada
| | - Ashley Wagner
- National Research Council of CANADA - Nanotechnology Research Centre, Edmonton, Alberta, Canada
| | - Sarang P Gumfekar
- Department of Chemical Engineering, Indian Institute of Technology, Ropar, India
| | - Douglas Vick
- National Research Council of CANADA - Nanotechnology Research Centre, Edmonton, Alberta, Canada
| | - Patrick Price
- National Research Council of CANADA - Nanotechnology Research Centre, Edmonton, Alberta, Canada
| | - Darren Makeiff
- National Research Council of CANADA - Nanotechnology Research Centre, Edmonton, Alberta, Canada
| | - Marianna Kulka
- National Research Council of CANADA - Nanotechnology Research Centre, Edmonton, Alberta, Canada
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6
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Marshall AG, Damo SM, Hinton A. Revisiting focused ion beam scanning electron microscopy. Trends Biochem Sci 2023; 48:585-586. [PMID: 36990957 DOI: 10.1016/j.tibs.2023.02.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 01/27/2023] [Accepted: 02/23/2023] [Indexed: 03/29/2023]
Affiliation(s)
- Andrea G Marshall
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37232, USA
| | - Steven M Damo
- Department of Life and Physical Sciences, Fisk University, Nashville, TN, 37232, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN, 37232, USA
| | - Antentor Hinton
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37232, USA.
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7
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Egerton R, Hayashida M, Malac M. Transmission electron microscopy of thick polymer and biological specimens. Micron 2023; 169:103449. [PMID: 37001476 DOI: 10.1016/j.micron.2023.103449] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 03/22/2023] [Accepted: 03/22/2023] [Indexed: 03/30/2023]
Abstract
We explore the properties of elastic and inelastic scattering in a thick organic specimen, together with the mechanisms that provide contrast in a transmission electron microscope (TEM) and scanning-transmission electron microscope (STEM). Experimental data recorded from amorphous carbon are used to predict the bright-field image intensity, mass-thickness contrast and dose-limited resolution as a function of thickness, objective-aperture size, and primary-electron energy E0. Combining this information with estimates of chromatic aberration, objective-aperture diffraction and beam broadening in the specimen, we calculate the achievable TEM and STEM resolution to be around 4 nm at E0 = 300 keV (or below 3 nm at MeV energies) for a 10 µm-diameter objective aperture and 1 - 2 µm thickness of hydrated biological tissue. The 3 MeV resolution for a 10-μm tissue sample is probably closer to 10 nm. We also comment on the error involved in quadrature addition of resolution factors, when one or more of the point-spread functions are non-Gaussian.
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8
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Martín C, Bachiller A, Fernández-Blázquez JP, Nishina Y, Jorcano JL. Plasma-Derived Fibrin Hydrogels Containing Graphene Oxide for Infections Treatment. ACS MATERIALS LETTERS 2023; 5:1245-1255. [PMID: 38323142 PMCID: PMC10842975 DOI: 10.1021/acsmaterialslett.2c01044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 03/20/2023] [Indexed: 02/08/2024]
Abstract
Wound infection is inevitable in most patients suffering from extensive burns or chronic ulcers, and there is an urgent demand for the production of bactericidal dressings to be used as grafts to restore skin functionalities. In this context, the present study explores the fabrication of plasma-derived fibrin hydrogels containing bactericidal hybrids based on graphene oxide (GO). The hydrogels were fully characterized regarding gelation kinetics, mechanical properties, and internal hydrogel structures by disruptive cryo scanning electron microscopies (cryo-SEMs). The gelation kinetic experiments revealed an acceleration of the gel formation when GO was added to the hydrogels in a concentration of up to 0.2 mg/mL. The cryo-SEM studies showed up a decrease of the pore size when GO was added to the network, which agreed with a faster area contraction and a higher compression modulus of the hydrogels that contained GO, pointing out the critical structural role of the nanomaterial. Afterward, to study the bactericidal ability of the gels, GO was used as a carrier, loading streptomycin (STREP) on its surface. The loading content of the drug to form the hybrid (GO/STREP) resulted in 50.2% ± 4.7%, and the presence of the antibiotic was also demonstrated by Raman spectroscopy, Z-potential studies, and thermogravimetric analyses. The fibrin-derived hydrogels containing GO/STREP showed a dose-response behavior according to the bactericidal hybrid concentration and allowed a sustained release of the antibiotic at a programmed rate, leading to drug delivery over a prolonged period of time.
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Affiliation(s)
- Cristina Martín
- Department
of Bioengineering, Universidad Carlos III
de Madrid, Leganés 28911, Spain
| | - Ariadna Bachiller
- Department
of Bioengineering, Universidad Carlos III
de Madrid, Leganés 28911, Spain
| | | | - Yuta Nishina
- Graduate
School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan
- Research
Core for Interdisciplinary Sciences, Okayama
University, Okayama 700-8530, Japan
| | - José L. Jorcano
- Department
of Bioengineering, Universidad Carlos III
de Madrid, Leganés 28911, Spain
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9
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Merryweather DJ, Weston N, Roe J, Parmenter C, Lewis MP, Roach P. Exploring the microstructure of hydrated collagen hydrogels under scanning electron microscopy. J Microsc 2023; 290:40-52. [PMID: 36718074 DOI: 10.1111/jmi.13174] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 01/05/2023] [Accepted: 01/25/2023] [Indexed: 02/01/2023]
Abstract
Collagen hydrogels are a rapidly expanding platform in bioengineering and soft materials engineering for novel applications focused on medical therapeutics, medical devices and biosensors. Observations linking microstructure to material properties and function enables rational design strategies to control this space. Visualisation of the microscale organisation of these soft hydrated materials presents unique technical challenges due to the relationship between hydration and the molecular organisation of a collagen gel. Scanning electron microscopy is a robust tool widely employed to visualise and explore materials on the microscale. However, investigation of collagen gel microstructure is difficult without imparting structural changes during preparation and/or observation. Electrons are poorly propagated within liquid-phase materials, limiting the ability of electron microscopy to interrogate hydrated gels. Sample preparation techniques to remove water induce artefactual changes in material microstructure particularly in complex materials such as collagen, highlighting a critical need to develop robust material handling protocols for the imaging of collagen hydrogels. Here a collagen hydrogel is fabricated, and the gel state explored under high-vacuum (10-6 Pa) and low-vacuum (80-120 Pa) conditions, and in an environmental SEM chamber. Visualisation of collagen fibres is found to be dependent on the degree of sample hydration, with higher imaging chamber pressures and humidity resulting in decreased feature fidelity. Reduction of imaging chamber pressure is used to induce evaporation of gel water content, revealing collagen fibres of significantly larger diameter than observed in samples dehydrated prior to imaging. Rapid freezing and cryogenic handling of the gel material is found to retain a porous 3D structure following sublimation of the gel water content. Comparative analysis of collagen hydrogel materials demonstrates the care needed when preparing hydrogel samples for electron microscopy.
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Affiliation(s)
- Daniel J Merryweather
- Department of Chemistry, School of Science, Loughborough University, Leicestershire, UK
| | - Nicola Weston
- Nanoscale and Microscale Research Centre, University of Nottingham, Nottingham, UK
| | - Jordan Roe
- Department of Chemistry, School of Science, Loughborough University, Leicestershire, UK.,Department of Materials, Loughborough University, Leicestershire, UK
| | | | - Mark P Lewis
- National Centre for Sport and Exercise Medicine (NCSEM), School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire, UK
| | - Paul Roach
- Department of Chemistry, School of Science, Loughborough University, Leicestershire, UK
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10
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Okada S, Chen C. A Novel Cryogenic Adhesive Retaining Fluidity at Dry-Ice Temperature for Low-Temperature Scanning Electron Microscopy. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2022; 28:1-11. [PMID: 36062382 DOI: 10.1017/s1431927622012296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Scanning electron microscopy operated at cryogenic temperature (cryo-SEM) is a powerful tool for investigating surface and cross-sectional nanostructures of water-containing samples. Typically, cryo-SEM samples are frozen just before observation in specific metal carriers. However, pre-frozen samples are also of interest, such as frozen food and freeze-stored animal samples. In such cases, sample mounting with a defined orientation is required, but there has been a lack of ideal conductive adhesives that can be used without increasing the sample temperature. Here, we developed a mixture of graphite oxide and 1,3-butanediol as an adhesive, capable of gluing samples at dry-ice temperature and is frozen below that temperature. Dispersion of graphite oxide increased the conductivity and reduced the charge-up contrast. Acquisition of energy-dispersive X-ray spectrum, cross-sectional ion milling, and high-resolution imaging were successfully achieved using the adhesive. We tested and confirmed the usefulness of this new adhesive by applying it to cryo-SEM surface imaging of diatomite, freeze-fractured cross-sectional imaging of chicken liver, and ion milling cross-sectional imaging of a deep-sea snail. The new adhesive is not only useful for food science and field-preserved biological samples but also potentially applicable to wider fields such as archaeological and biological samples preserved under permafrost.
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Affiliation(s)
- Satoshi Okada
- Super-cutting-edge Grand and Advanced Research (SUGAR) Program, Institute for Extra-Cutting-Edge Science and Technology Avant-Garde Research (X-star), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka, Kanagawa 237-0061, Japan
| | - Chong Chen
- Super-cutting-edge Grand and Advanced Research (SUGAR) Program, Institute for Extra-Cutting-Edge Science and Technology Avant-Garde Research (X-star), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka, Kanagawa 237-0061, Japan
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11
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Gong Y, Gu T, Ling L, Qiu R, Zhang WX. Visualizing hazardous solids with cryogenic electron microscopy (Cryo-EM). JOURNAL OF HAZARDOUS MATERIALS 2022; 436:129192. [PMID: 35739722 DOI: 10.1016/j.jhazmat.2022.129192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 05/16/2022] [Accepted: 05/17/2022] [Indexed: 06/15/2023]
Abstract
Recent developments point to exciting potential of cryogenic electron microscopy (cryo-EM) for fundamental environmental research, especially for characterizing environmental samples with a high-water content. As a matter of fact, most environmental materials including soils, sediments, biomass, solid wastes and sludge are hydrated. This perspective provides a brief synopsis of cryo-EM and highlights emerging applications in environmental research. With cryogenic techniques, specimens are preserved by rapid freezing and observed with electron microscopes operating at high-vacuum and low temperature to keep the ice in amorphous state and reduce the effect of radiation damage. So far, cryo-EM has been successfully applied to advance fundamental understanding of physical, chemical and biological mechanisms due to its desirable properties to maintain the native state of hydrated samples and visualize structures at high resolution in three dimensions. The cryo-EM technique also has significant applications to the technology development of pathogen detection, sludge dewatering, waste treatment, and green chemical production from cellular biomass as cellular water content can be clearly observed and manipulated at the single cell level.
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Affiliation(s)
- Yuxiu Gong
- State Key Laboratory for Pollution Control, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, China
| | - Tianhang Gu
- State Key Laboratory for Pollution Control, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, China
| | - Lan Ling
- State Key Laboratory for Pollution Control, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
| | - Rongliang Qiu
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China
| | - Wei-Xian Zhang
- State Key Laboratory for Pollution Control, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, China; Guangdong Laboratory for Lingnan Modern Agriculture, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China.
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12
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Gundlach KA, Briegel A. Zooming in on host-symbiont interactions: advances in cryo-EM sample processing methods and future application to symbiotic tissues. Symbiosis 2022. [DOI: 10.1007/s13199-022-00859-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AbstractAnimals, plants, and fungi live in a microbe-dominated world. Investigating the interactions and processes at the host-microbe interface offers insight to how bacteria influence the development, health, and disease of the host. Optimization of existing imaging technologies and development of novel instrumentation will provide the tools needed to fully understand the dynamic relationship that occurs at the host-microbe interface throughout the lifetime of the host. In this review, we describe the current methods used in cryo-electron microscopy (cryo-EM) including cryo-fixation, sample processing, FIB-SEM, and cryotomography. Further, we highlight the new advances associated with these methods that open the cryo-EM discipline to large, complex multicellular samples, like symbiotic tissues. We describe the advantages and challenges associated with correlative imaging techniques and sample thinning methods like lift-out. By highlighting recent pioneering studies in the large-volume or symbiotic sample workflows, we provide insight into how symbiotic model systems will benefit from cryo-EM methods to provide artefact-free, near-native, macromolecular-scale resolution imaging at the host-microbe interface throughout the development and maintenance of symbiosis. Cryo-EM methods have brought a deep fundamental understanding of prokaryotic biology since its conception. We propose the application of existing and novel cryo-EM techniques to symbiotic systems is the logical next step that will bring an even greater understanding how microbes interact with their host tissues.
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Zechmann B, Möstl S, Zellnig G. Volumetric 3D reconstruction of plant leaf cells using SEM, ion milling, TEM, and serial sectioning. PLANTA 2022; 255:118. [PMID: 35522384 DOI: 10.1007/s00425-022-03905-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 04/26/2022] [Indexed: 06/14/2023]
Abstract
Focused ion beam scanning electron microscopy is well suited for volumetric extractions and 3D reconstructions of plant cells and its organelles. The three-dimensional (3D) reconstruction of individual plant cells is an important tool to extract volumetric data of organelles and is necessary to fully understand ultrastructural changes and adaptations of plants to their environment. Methods such as the 3D reconstruction of cells based on light microscopical images often lack the resolution necessary to clearly reconstruct all cell compartments within a cell. The 3D reconstruction of cells through serial sectioning transmission electron microscopy (ssTEM) and focused ion beam scanning electron microscopy (FIB-SEM) are powerful alternatives but not widely used in plant sciences. Here, we present a method for the 3D reconstruction and volumetric extraction of plant cells based on FIB milling and compare the results with 3D reconstructions obtained with ssTEM. When compared to 3D reconstruction based on ssTEM, FIB-SEM delivered similar results. The data extracted in this study demonstrated that tobacco cells were larger (31410 µm3) than pumpkin cells (20697 µm3) and contained more chloroplasts (175 vs. 124), mitochondria (1317 vs. 291) and peroxisomes (745 vs. 79). While individual chloroplasts, mitochondria, peroxisomes were larger in pumpkin plants (25, 53, and 50%, respectively) they covered more total volume in tobacco plants (5390, 395, 374 µm3, respectively) due to their higher number per cell when compared to pumpkin plants (4762, 134, 59 µm3, respectively). While image acquisition with FIB-SEM was automated, software controlled, and less difficult than ssTEM, FIB milling was slower and sections could not be revised or re-imaged as they were destroyed by the ion beam. Nevertheless, the results in this study demonstrated that both, FIB-SEM and ssTEM, are powerful tools for the 3D reconstruction of and volumetric extraction from plant cells and that there were large differences in size, number, and organelle composition between pumpkin and tobacco cells.
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Affiliation(s)
- Bernd Zechmann
- Center for Microscopy and Imaging, Baylor University, One Bear Place #97046, Waco, TX, 76798, USA.
| | - Stefan Möstl
- Institute of Biology, Plant Sciences, University of Graz, NAWI Graz, Schubertstrasse 51, 8010, Graz, Austria
| | - Günther Zellnig
- Institute of Biology, Plant Sciences, University of Graz, NAWI Graz, Schubertstrasse 51, 8010, Graz, Austria
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14
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Wightman R. An Overview of Cryo-Scanning Electron Microscopy Techniques for Plant Imaging. PLANTS (BASEL, SWITZERLAND) 2022; 11:plants11091113. [PMID: 35567113 PMCID: PMC9106016 DOI: 10.3390/plants11091113] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 04/14/2022] [Accepted: 04/14/2022] [Indexed: 05/02/2023]
Abstract
Many research questions require the study of plant morphology, in particular cells and tissues, as close to their native context as possible and without physical deformations from some preparatory chemical reagents or sample drying. Cryo-scanning electron microscopy (cryoSEM) involves rapid freezing and maintenance of the sample at an ultra-low temperature for detailed surface imaging by a scanning electron beam. The data are useful for exploring tissue/cell morphogenesis, plus an additional cryofracture/cryoplaning/milling step gives information on air and water spaces as well as subcellular ultrastructure. This review gives an overview from sample preparation through to imaging and a detailed account of how this has been applied across diverse areas of plant research. Future directions and improvements to the technique are discussed.
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Affiliation(s)
- Raymond Wightman
- The Sainsbury Laboratory, University of Cambridge, Bateman Street, Cambridge CB2 1LR, UK
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15
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16
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Wasowicz TJ. Neutral Dissociation of Pyridine Evoked by Irradiation of Ionized Atomic and Molecular Hydrogen Beams. Int J Mol Sci 2021; 23:205. [PMID: 35008633 PMCID: PMC8745593 DOI: 10.3390/ijms23010205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 12/19/2021] [Accepted: 12/22/2021] [Indexed: 11/17/2022] Open
Abstract
The interactions of ions with molecules and the determination of their dissociation patterns are challenging endeavors of fundamental importance for theoretical and experimental science. In particular, the investigations on bond-breaking and new bond-forming processes triggered by the ionic impact may shed light on the stellar wind interaction with interstellar media, ionic beam irradiations of the living cells, ion-track nanotechnology, radiation hardness analysis of materials, and focused ion beam etching, deposition, and lithography. Due to its vital role in the natural environment, the pyridine molecule has become the subject of both basic and applied research in recent years. Therefore, dissociation of the gas phase pyridine (C5H5N) into neutral excited atomic and molecular fragments following protons (H+) and dihydrogen cations (H2+) impact has been investigated experimentally in the 5-1000 eV energy range. The collision-induced emission spectroscopy has been exploited to detect luminescence in the wavelength range from 190 to 520 nm at the different kinetic energies of both cations. High-resolution optical fragmentation spectra reveal emission bands due to the CH(A2Δ→X2Πr; B2Σ+→X2Πr; C2Σ+→X2Πr) and CN(B2Σ+→X2Σ+) transitions as well as atomic H and C lines. Their spectral line shapes and qualitative band intensities are examined in detail. The analysis shows that the H2+ irradiation enhances pyridine ring fragmentation and creates various fragments more pronounced than H+ cations. The plausible collisional processes and fragmentation pathways leading to the identified products are discussed and compared with the latest results obtained in cation-induced fragmentation of pyridine.
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Affiliation(s)
- Tomasz J Wasowicz
- Division of Complex Systems Spectroscopy, Institute of Physics and Applied Computer Science, Faculty of Applied Physics and Mathematics, Gdansk University of Technology, ul. G. Narutowicza 11/12, 80-233 Gdansk, Poland
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17
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Zhang S, Ju W, Chen X, Zhao Y, Feng L, Yin Z, Chen X. Hierarchical ultrastructure: An overview of what is known about tendons and future perspective for tendon engineering. Bioact Mater 2021; 8:124-139. [PMID: 34541391 PMCID: PMC8424392 DOI: 10.1016/j.bioactmat.2021.06.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 06/07/2021] [Accepted: 06/07/2021] [Indexed: 12/27/2022] Open
Abstract
Abnormal tendons are rarely ever repaired to the natural structure and morphology of normal tendons. To better guide the repair and regeneration of injured tendons through a tissue engineering method, it is necessary to have insights into the internal morphology, organization, and composition of natural tendons. This review summarized recent researches on the structure and function of the extracellular matrix (ECM) components of tendons and highlight the application of multiple detection methodologies concerning the structure of ECMs. In addition, we look forward to the future of multi-dimensional biomaterial design methods and the potential of structural repair for tendon ECM components. In addition, focus is placed on the macro to micro detection methods for tendons, and current techniques for evaluating the extracellular matrix of tendons at the micro level are introduced in detail. Finally, emphasis is given to future extracellular matrix detection methods, as well as to how future efforts could concentrate on fabricating the biomimetic tendons. Summarize recent research on the structure and function of the extracellular matrix (ECM) components of tendons. Comments on current research methods concerning the structure of ECMs. Perspective on the future of multi-dimensional detection techniques and structural repair of tendon ECM components.
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Affiliation(s)
- Shichen Zhang
- Dr. Li Dak Sum & Yip Yio Chin Center for Stem Cell and Regenerative Medicine and Department of Orthopedic Surgery of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310052, China.,Key Laboratory of Tissue Engineering and Regenerative Medicine of Zhejiang Province, School of Medicine, Zhejiang University, Hangzhou, 310058, China
| | - Wei Ju
- Key Laboratory of Tissue Engineering and Regenerative Medicine of Zhejiang Province, School of Medicine, Zhejiang University, Hangzhou, 310058, China
| | - Xiaoyi Chen
- Guangxi Key Laboratory of Regenerative Medicine, Guangxi-ASEAN Collaborative Innovation Center for Major Disease Prevention and Treatment, Guangxi Medical University, Guangxi, 530021, China
| | - Yanyan Zhao
- Dr. Li Dak Sum & Yip Yio Chin Center for Stem Cell and Regenerative Medicine and Department of Orthopedic Surgery of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310052, China.,Key Laboratory of Tissue Engineering and Regenerative Medicine of Zhejiang Province, School of Medicine, Zhejiang University, Hangzhou, 310058, China
| | - Lingchong Feng
- State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou, 310058, Zhejiang, China
| | - Zi Yin
- Key Laboratory of Tissue Engineering and Regenerative Medicine of Zhejiang Province, School of Medicine, Zhejiang University, Hangzhou, 310058, China.,Dr. Li Dak Sum & Yip Yio Chin Center for Stem Cell and Regenerative Medicine and Regenerative Medicine and Department of Orthopedic Surgery of Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, 310058, China.,Department of Sports Medicine, School of Medicine, Zhejiang University, Hangzhou, 310058, China.,China Orthopedic Regenerative Medicine Group (CORMed), Hangzhou, 310058, China
| | - Xiao Chen
- Dr. Li Dak Sum & Yip Yio Chin Center for Stem Cell and Regenerative Medicine and Department of Orthopedic Surgery of the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310052, China.,Key Laboratory of Tissue Engineering and Regenerative Medicine of Zhejiang Province, School of Medicine, Zhejiang University, Hangzhou, 310058, China.,Guangxi Key Laboratory of Regenerative Medicine, Guangxi-ASEAN Collaborative Innovation Center for Major Disease Prevention and Treatment, Guangxi Medical University, Guangxi, 530021, China.,Department of Sports Medicine, School of Medicine, Zhejiang University, Hangzhou, 310058, China.,China Orthopedic Regenerative Medicine Group (CORMed), Hangzhou, 310058, China
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18
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Phengchat R, Malac M, Hayashida M. Chromosome inner structure investigation by electron tomography and electron diffraction in a transmission electron microscope. Chromosome Res 2021; 29:63-80. [PMID: 33733375 DOI: 10.1007/s10577-021-09661-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 02/19/2021] [Accepted: 03/09/2021] [Indexed: 10/21/2022]
Abstract
Our understanding of the inner structure of metaphase chromosomes remains inconclusive despite intensive studies using multiple imaging techniques. Transmission electron microscopy has been extensively used to visualize chromosome ultrastructure. This review summarizes recent results obtained using two transmission electron microscopy-based techniques: electron tomography and electron diffraction. Electron tomography allows advanced three-dimensional imaging of chromosomes, while electron diffraction detects the presence of periodic structures within chromosomes. The combination of these two techniques provides results contributing to the understanding of local structural organization of chromatin fibers within chromosomes.
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Affiliation(s)
- Rinyaporn Phengchat
- Graduate School of Human Development and Environment, Kobe University, 3-11 Tsurukabuto, Nada-ku, Kobe, 657-8501, Japan.
| | - Marek Malac
- Nanotechnology Research Centre, National Research of Council, 11421 Saskatchewan Drive, T6G 2 M9, Edmonton, Alberta, Canada.,Department of Physics, University of Alberta, Edmonton, Alberta, T6G 2E1, Canada
| | - Misa Hayashida
- Nanotechnology Research Centre, National Research of Council, 11421 Saskatchewan Drive, T6G 2 M9, Edmonton, Alberta, Canada
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19
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Yang JE, Larson MR, Sibert BS, Shrum S, Wright ER. CorRelator: Interactive software for real-time high precision cryo-correlative light and electron microscopy. J Struct Biol 2021; 213:107709. [PMID: 33610654 PMCID: PMC8601405 DOI: 10.1016/j.jsb.2021.107709] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 01/06/2021] [Accepted: 02/11/2021] [Indexed: 12/31/2022]
Abstract
Cryo-correlative light and electron microscopy (CLEM) is a technique that uses the spatiotemporal cues from fluorescence light microscopy (FLM) to investigate the high-resolution ultrastructure of biological samples by cryo-electron microscopy (cryo-EM). Cryo-CLEM provides advantages for identifying and distinguishing fluorescently labeled proteins, macromolecular complexes, and organelles from the cellular environment. Challenges remain on how correlation workflows and software tools are implemented on different microscope platforms to support automated cryo-EM data acquisition. Here, we present CorRelator: an open-source desktop application that bridges between cryo-FLM and real-time cryo-EM/ET automated data collection. CorRelator implements a pixel-coordinate-to-stage-position transformation for flexible, high accuracy on-the-fly and post-acquisition correlation. CorRelator can be integrated into cryo-CLEM workflows and easily adapted to standard fluorescence and transmission electron microscope (TEM) system configurations. CorRelator was benchmarked under live-cell and cryogenic conditions using several FLM and TEM instruments, demonstrating that CorRelator reliably supports real-time, automated correlative cryo-EM/ET acquisition, through a combination of software-aided and interactive alignment. CorRelator is a cross-platform software package featuring an intuitive Graphical User Interface (GUI) that guides the user through the correlation process. CorRelator source code is available at: https://github.com/wright-cemrc-projects/corr.
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Affiliation(s)
- Jie E Yang
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, United States; Cryo-Electron Microscopy Research Center, Department of Biochemistry, University of Wisconsin, Madison, WI 53706, United States; Midwest Center for Cryo-Electron Tomography, Department of Biochemistry, University of Wisconsin, Madison, WI 53706, United States
| | - Matthew R Larson
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, United States; Cryo-Electron Microscopy Research Center, Department of Biochemistry, University of Wisconsin, Madison, WI 53706, United States; Midwest Center for Cryo-Electron Tomography, Department of Biochemistry, University of Wisconsin, Madison, WI 53706, United States
| | - Bryan S Sibert
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, United States; Cryo-Electron Microscopy Research Center, Department of Biochemistry, University of Wisconsin, Madison, WI 53706, United States; Midwest Center for Cryo-Electron Tomography, Department of Biochemistry, University of Wisconsin, Madison, WI 53706, United States
| | - Samantha Shrum
- Biophysics Graduate Program, University of Wisconsin, Madison, WI 53706, United States
| | - Elizabeth R Wright
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, United States; Cryo-Electron Microscopy Research Center, Department of Biochemistry, University of Wisconsin, Madison, WI 53706, United States; Biophysics Graduate Program, University of Wisconsin, Madison, WI 53706, United States; Morgridge Institute for Research, Madison, WI, 53715, United States; Midwest Center for Cryo-Electron Tomography, Department of Biochemistry, University of Wisconsin, Madison, WI 53706, United States.
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20
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Parmenter CD, Nizamudeen ZA. Cryo-FIB-lift-out: practically impossible to practical reality. J Microsc 2020; 281:157-174. [PMID: 32815145 DOI: 10.1111/jmi.12953] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 08/05/2020] [Accepted: 08/08/2020] [Indexed: 01/14/2023]
Abstract
In this paper, we explore the development of the Cryo-Lift-Out (cryo-LO) technique as preparation tool for cryogenic transmission electron microscopy (cryo-TEM). What started in early work defying what was considered 'practically impossible' has developed into state-of-the-art practical reality. This paper presents the key hardware, basic principles and key considerations for the practical usage of cryogenic Lift-Out for those new to the field. Detailed protocols and in-depth description of considerations and points for further development are presented. The authors have attempted to formalise everything known about the technique gathered together from their expertise gained in the development of this approach. LAY DESCRIPTION: A major challenge in electron microscopy is the production of suitable samples from hydrated biological and soft-matter materials for subnanometre resolution imaging in a cryo-Transmission Electron Microscope (TEM). A well-known solution for room temperature materials is called (in situ) Lift-Out. It uses a fine needle that picks up a tiny section called a lamella. Lamellae are made by a Focused Ion Beam (FIB). In this paper, we seek to set out the beginnings of Lift-Out sample preparation conducted under cryogenic conditions and the development of this approach as applied to frozen, hydrated biological and soft-matter samples. We discuss the required basic hardware and provide a thorough description of developed protocols. We aim at those new to the field of cryo-Lift-Out to fully educate them in the finer points of hardware setup and practical considerations when attempting to perform cryo-Lift-Out and to demonstrate what has been achieved thus far. We also discuss areas of further improvement and talking points for the future direction of this promising sample preparation technique.
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Affiliation(s)
| | - Zubair Ahmed Nizamudeen
- Nottingham Nanoscale and Microscale Research Centre, University of Nottingham, Nottingham, UK.,Division of Cancer and Stem Cells, Nottingham Biodiscovery Institute, The University of Nottingham, Nottingham, UK
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21
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DE Winter DAM, Hsieh C, Marko M, Hayles MF. Cryo-FIB preparation of whole cells and tissue for cryo-TEM: use of high-pressure frozen specimens in tubes and planchets. J Microsc 2020; 281:125-137. [PMID: 32691851 PMCID: PMC7891314 DOI: 10.1111/jmi.12943] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 05/27/2020] [Accepted: 07/13/2020] [Indexed: 01/15/2023]
Abstract
The desire to study macromolecular complexes within their cellular context requires the ability to produce thin samples suitable for cryo‐TEM (cryo‐transmission electron microscope) investigations. In this paper, we discuss two similar approaches, which were developed independently in Utrecht (the Netherlands) and Albany (USA). The methods are particularly suitable for both tissue samples and cell suspensions prepared by a high‐pressure freezer (HPF). The workflows are explained with particular attention to potential pitfalls, while underlying principles are highlighted (‘why to do so’). Although both workflows function with a high success rate, full execution requires considerable experience and remains demanding. In addition, throughput is low. We hope to encourage other research groups worldwide to take on the challenge of improving the HPF– cryo‐FIB‐SEM – cryo‐TEM workflow. We discuss a number of suggestions to this end. Lay Description Life is ultimately dictated by the interaction of molecules in our bodies. Highly complex equipment is being used and further developed to study these interactions. The present paper describes methods to prepare small, very thin lamellae (area of 5×5 µm2, thickness 50–300 nm) of a cell to be studied in a cryo‐transmission electron microscope (cryo‐TEM). Special care must be taken to preserve the natural state of molecules in their natural environment. In the case of cryo‐TEM, the samples must be frozen and kept frozen to be compatible with the vacuum conditions in the microscope. The frozen condition imposes technical challenges which are addressed. Two approaches to obtain the thin lamellae are described. Both make use of a focused ion beam (FIB) microscope. The FIB allows removal of material with nanometre precision by focusing a beam of ionised atoms (gallium ions) onto the sample. Careful control of the FIB allows cutting out of the required thin lamellae. In both strategies, the thin lamellae remain attached to the original sample, and the ensemble of sample with section and sample holder is transported from the FIB microscope to the TEM while being kept frozen.
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Affiliation(s)
- D A M DE Winter
- Environmental Hydrogeology, Department of Earth Sciences, Utrecht University, Princetonlaan 8a, Utrecht, the Netherlands
| | - C Hsieh
- New York State Department of Health, Wadsworth Center, Empire State Plaza, Albany, New York, U.S.A
| | - M Marko
- New York State Department of Health, Wadsworth Center, Empire State Plaza, Albany, New York, U.S.A.,College of Nanoscale Science and Engineering, SUNY Polytechnic Institute, Albany, New York, U.S.A
| | - M F Hayles
- Cryo-FIB-SEM Technologist, Eindhoven, the Netherlands
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