1
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Jeong S, Kim J, Koh D, Lee JC. Simultaneously enhancing the resolution and signal-to-background ratio in STED optical nanoscopy via differential depletion. OPTICS EXPRESS 2023; 31:37549-37563. [PMID: 38017882 DOI: 10.1364/oe.505430] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 10/08/2023] [Indexed: 11/30/2023]
Abstract
STED (stimulated emission depletion) far-field optical nanoscopy achieves resolution beyond the diffraction limit by depleting fluorescence at the periphery of excitation with a donut-shaped depletion laser. What is traded off with the superior resolution of STED nanoscopy is the unwanted elevation of structured background noise which hampers the quality of STED images. Here, we alleviate the background noise problem by adopting the differential stimulated emission depletion (diffSTED) approach. In diffSTED nanoscopy, signals obtained with different depletion strengths are compared and properly subtracted to remove two major background noise sources in STED nanoscopy. We show via simulations that by using diffSTED nanoscopy, background noise is significantly decreased, and the image contrast is improved. In addition, we show by simulation and analytical calculation that diffSTED improves resolution simultaneously. We assess the effect of different parameters, such as the STED beam intensity, depletion intensity ratio of two STED beams, and the subtraction factor, on the signal-to-background ratio (SBR) and the resolution of diffSTED nanoscopy. We introduce a logical algorithm to determine the optimal subtraction factor and the depletion intensity ratio. DiffSTED nanoscopy is a versatile technique that can be readily applied to any STED system without requiring any hardware modifications. We predict the wide applicability of diffSTED for its enhanced resolution, improved SBR, and easiness of implementation.
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2
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Sedeh AB, Kobitski A, Dai S, Eroğlu-Kayıkçı S, Nienhaus K, Hilbert L, Nienhaus GU. Stimulated emission double depletion nanoscopy with background correction at the single-pixel level. OPTICS LETTERS 2023; 48:5791-5794. [PMID: 37910760 DOI: 10.1364/ol.502001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 10/12/2023] [Indexed: 11/03/2023]
Abstract
Fluorescence microscopy images are inevitably tainted by background contributions including emission from out-of-focus planes, scattered light, and detector noise. In stimulated emission depletion (STED) nanoscopy, an additional, method-specific background arises from incomplete depletion and re-excitation by the depletion beam. Various approaches have been proposed to remove the background from a STED image, some of which rely on the acquisition of a separate background image that is subtracted from the STED image with a weighting factor. Using stimulated emission double depletion (STEDD) nanoscopy, we observed that the weighting factor varies locally in densely labeled samples, so that background removal with a single (global) weighting factor generates local image artifacts due to incorrect background subtraction. Here we present an algorithm that computes the optimal weighting factor at the single-pixel level, yielding a difference image with excellent suppression of low-frequency background.
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3
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Fang X, Wen K, An S, Zheng J, Li J, Zalevsky Z, Gao P. Reconstruction algorithm using 2N+1 raw images for structured illumination microscopy. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2023; 40:765-773. [PMID: 37132974 DOI: 10.1364/josaa.483884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
This paper presents a structured illumination microscopy (SIM) reconstruction algorithm that allows the reconstruction of super-resolved images with 2N + 1 raw intensity images, with N being the number of structured illumination directions used. The intensity images are recorded after using a 2D grating for the projection fringe and a spatial light modulator to select two orthogonal fringe orientations and perform phase shifting. Super-resolution images can be reconstructed from the five intensity images, enhancing the imaging speed and reducing the photobleaching by 17%, compared to conventional two-direction and three-step phase-shifting SIM. We believe the proposed technique will be further developed and widely applied in many fields.
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4
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Zheng J, Fang X, Wen K, Li J, Ma Y, Liu M, An S, Li J, Zalevsky Z, Gao P. Large-field lattice structured illumination microscopy. OPTICS EXPRESS 2022; 30:27951-27966. [PMID: 36236953 DOI: 10.1364/oe.461615] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 06/27/2022] [Indexed: 06/16/2023]
Abstract
In this paper, we present large-field, five-step lattice structured illumination microscopy (Lattice SIM). This method utilizes a 2D grating for lattice projection and a spatial light modulator (SLM) for phase shifting. Five phase-shifted intensity images are recorded to reconstruct a super-resolution image, enhancing the imaging speed and reducing the photo-bleaching both by 17%, compared to conventional two-direction and three-shift SIM. Furthermore, lattice SIM has a three-fold spatial bandwidth product (SBP) enhancement compared to SLM/DMD-based SIM, of which the fringe number is limited by the SLM/DMD pixel number. We believe that the proposed technique will be further developed and widely applied in many fields.
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5
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Liu Y, Song Y, Zhang J, Yang Z, Peng X, Yan W, Qu J. Responsive Carbonized Polymer Dots for Optical Super-resolution and Fluorescence Lifetime Imaging of Nucleic Acids in Living Cells. ACS APPLIED MATERIALS & INTERFACES 2021; 13:50733-50743. [PMID: 34670368 DOI: 10.1021/acsami.1c13943] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The rapid development of advanced optical imaging methods including stimulated emission depletion (STED) and fluorescence lifetime imaging microscopy (FLIM) has provided powerful tools for real-time observation of submicrometer biotargets to achieve unprecedented spatial and temporal resolutions. However, the practical imaging qualities are often limited by the performance of fluorescent probes, leading to unsatisfactory results. In particular, long-term imaging of nucleic acids in living cells with STED and FLIM remained desirable yet challenging due to the lack of competent probes combining targeting specificity, biocompatibility, low power requirement, and photostability. In this work, we rationally designed and synthesized a nanosized carbonized polymer dot (CPD) material, CPDs-3, with highly efficient and photostable emission for the super-resolution and fluorescence lifetime imaging of nucleic acids in living cells. The as-fabricated nanoprobe showed responsive emission properties upon binding with nucleic acids, providing an excellent signal-to-noise ratio in both spatial and temporal dimensions. Moreover, the characteristic saturation intensity value of CPDs-3 was as low as 0.68 mW (0.23 MW/cm2), allowing the direct observation of chromatin structures with subdiffraction resolution (90 nm) at very low excitation (<1 μW) and depletion power (<5 mW). Owing to its low toxicity, high photonic efficiency, and outstanding photostability, CPDs-3 was capable of performing long-term imaging both with STED and FLIM setups, demonstrating great potential for the dynamic study of nucleic acid functionalities in the long run.
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Affiliation(s)
- Yanfeng Liu
- Center for Biomedical Photonics & College of Physics and Optoelectronic Engineering, Key Laboratory of Optoelectronic Devices and Systems, Shenzhen University, Shenzhen 518060, China
| | - Yiwan Song
- Center for Biomedical Photonics & College of Physics and Optoelectronic Engineering, Key Laboratory of Optoelectronic Devices and Systems, Shenzhen University, Shenzhen 518060, China
| | - Jia Zhang
- Center for Biomedical Photonics & College of Physics and Optoelectronic Engineering, Key Laboratory of Optoelectronic Devices and Systems, Shenzhen University, Shenzhen 518060, China
| | - Zhigang Yang
- Center for Biomedical Photonics & College of Physics and Optoelectronic Engineering, Key Laboratory of Optoelectronic Devices and Systems, Shenzhen University, Shenzhen 518060, China
| | - Xiao Peng
- Center for Biomedical Photonics & College of Physics and Optoelectronic Engineering, Key Laboratory of Optoelectronic Devices and Systems, Shenzhen University, Shenzhen 518060, China
| | - Wei Yan
- Center for Biomedical Photonics & College of Physics and Optoelectronic Engineering, Key Laboratory of Optoelectronic Devices and Systems, Shenzhen University, Shenzhen 518060, China
| | - Junle Qu
- Center for Biomedical Photonics & College of Physics and Optoelectronic Engineering, Key Laboratory of Optoelectronic Devices and Systems, Shenzhen University, Shenzhen 518060, China
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6
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Pancholi A, Klingberg T, Zhang W, Prizak R, Mamontova I, Noa A, Sobucki M, Kobitski AY, Nienhaus GU, Zaburdaev V, Hilbert L. RNA polymerase II clusters form in line with surface condensation on regulatory chromatin. Mol Syst Biol 2021; 17:e10272. [PMID: 34569155 PMCID: PMC8474054 DOI: 10.15252/msb.202110272] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 08/26/2021] [Accepted: 09/10/2021] [Indexed: 12/15/2022] Open
Abstract
It is essential for cells to control which genes are transcribed into RNA. In eukaryotes, two major control points are recruitment of RNA polymerase II (Pol II) into a paused state, and subsequent pause release toward transcription. Pol II recruitment and pause release occur in association with macromolecular clusters, which were proposed to be formed by a liquid-liquid phase separation mechanism. How such a phase separation mechanism relates to the interaction of Pol II with DNA during recruitment and transcription, however, remains poorly understood. Here, we use live and super-resolution microscopy in zebrafish embryos to reveal Pol II clusters with a large variety of shapes, which can be explained by a theoretical model in which regulatory chromatin regions provide surfaces for liquid-phase condensation at concentrations that are too low for canonical liquid-liquid phase separation. Model simulations and chemical perturbation experiments indicate that recruited Pol II contributes to the formation of these surface-associated condensates, whereas elongating Pol II is excluded from these condensates and thereby drives their unfolding.
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Affiliation(s)
- Agnieszka Pancholi
- Zoological InstituteDepartment of Systems Biology and BioinformaticsKarlsruhe Institute of TechnologyKarlsruheGermany
- Institute of Biological and Chemical Systems—Biological Information ProcessingKarlsruhe Institute of TechnologyEggenstein‐LeopoldshafenGermany
| | - Tim Klingberg
- Department of BiologyFriedrich‐Alexander‐Universität Erlangen‐NürnbergErlangenGermany
- Max‐Planck‐Zentrum für Physik und MedizinErlangenGermany
| | - Weichun Zhang
- Institute of Applied PhysicsKarlsruhe Institute of TechnologyKarlsruheGermany
- Institute of NanotechnologyKarlsruhe Institute of TechnologyEggenstein‐LeopoldshafenGermany
| | - Roshan Prizak
- Institute of Biological and Chemical Systems—Biological Information ProcessingKarlsruhe Institute of TechnologyEggenstein‐LeopoldshafenGermany
| | - Irina Mamontova
- Institute of Biological and Chemical Systems—Biological Information ProcessingKarlsruhe Institute of TechnologyEggenstein‐LeopoldshafenGermany
| | - Amra Noa
- Institute of Biological and Chemical Systems—Biological Information ProcessingKarlsruhe Institute of TechnologyEggenstein‐LeopoldshafenGermany
| | - Marcel Sobucki
- Institute of Biological and Chemical Systems—Biological Information ProcessingKarlsruhe Institute of TechnologyEggenstein‐LeopoldshafenGermany
| | - Andrei Yu Kobitski
- Institute of Applied PhysicsKarlsruhe Institute of TechnologyKarlsruheGermany
| | - Gerd Ulrich Nienhaus
- Institute of Biological and Chemical Systems—Biological Information ProcessingKarlsruhe Institute of TechnologyEggenstein‐LeopoldshafenGermany
- Institute of Applied PhysicsKarlsruhe Institute of TechnologyKarlsruheGermany
- Institute of NanotechnologyKarlsruhe Institute of TechnologyEggenstein‐LeopoldshafenGermany
- Department of PhysicsUniversity of Illinois at Urbana‐ChampaignUrbanaILUSA
| | - Vasily Zaburdaev
- Department of BiologyFriedrich‐Alexander‐Universität Erlangen‐NürnbergErlangenGermany
- Max‐Planck‐Zentrum für Physik und MedizinErlangenGermany
| | - Lennart Hilbert
- Zoological InstituteDepartment of Systems Biology and BioinformaticsKarlsruhe Institute of TechnologyKarlsruheGermany
- Institute of Biological and Chemical Systems—Biological Information ProcessingKarlsruhe Institute of TechnologyEggenstein‐LeopoldshafenGermany
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7
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Liu Y, Peng Z, Peng X, Yan W, Yang Z, Qu J. Shedding New Lights Into STED Microscopy: Emerging Nanoprobes for Imaging. Front Chem 2021; 9:641330. [PMID: 33959587 PMCID: PMC8093789 DOI: 10.3389/fchem.2021.641330] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 02/15/2021] [Indexed: 12/29/2022] Open
Abstract
First reported in 1994, stimulated emission depletion (STED) microscopy has long been regarded as a powerful tool for real-time superresolved bioimaging . However, high STED light power (101∼3 MW/cm2) is often required to achieve significant resolution improvement, which inevitably introduces phototoxicity and severe photobleaching, damaging the imaging quality, especially for long-term cases. Recently, the employment of nanoprobes (quantum dots, upconversion nanoparticles, carbon dots, polymer dots, AIE dots, etc.) in STED imaging has brought opportunities to overcoming such long-existing issues. These nanomaterials designed for STED imaging show not only lower STED power requirements but also more efficient photoluminescence (PL) and enhanced photostability than organic molecular probes. Herein, we review the recent progress in the development of nanoprobes for STED imaging, to highlight their potential in improving the long-term imaging quality of STED microscopy and broadening its application scope. We also discuss the pros and cons for specific classes of nanoprobes for STED bioimaging in detail to provide practical references for biological researchers seeking suitable imaging kits, promoting the development of relative research field.
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Affiliation(s)
- Yanfeng Liu
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Zheng Peng
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Xiao Peng
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Wei Yan
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Zhigang Yang
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Junle Qu
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, China
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8
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Hüpfel M, Yu. Kobitski A, Zhang W, Nienhaus GU. Wavelet-based background and noise subtraction for fluorescence microscopy images. BIOMEDICAL OPTICS EXPRESS 2021; 12:969-980. [PMID: 33680553 PMCID: PMC7901331 DOI: 10.1364/boe.413181] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 12/27/2020] [Accepted: 01/15/2021] [Indexed: 05/20/2023]
Abstract
Fluorescence microscopy images are inevitably contaminated by background intensity contributions. Fluorescence from out-of-focus planes and scattered light are important sources of slowly varying, low spatial frequency background, whereas background varying from pixel to pixel (high frequency noise) is introduced by the detection system. Here we present a powerful, easy-to-use software, wavelet-based background and noise subtraction (WBNS), which effectively removes both of these components. To assess its performance, we apply WBNS to synthetic images and compare the results quantitatively with the ground truth and with images processed by other background removal algorithms. We further evaluate WBNS on real images taken with a light-sheet microscope and a super-resolution stimulated emission depletion microscope. For both cases, we compare the WBNS algorithm with hardware-based background removal techniques and present a quantitative assessment of the results. WBNS shows an excellent performance in all these applications and significantly enhances the visual appearance of fluorescence images. Moreover, it may serve as a pre-processing step for further quantitative analysis.
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Affiliation(s)
- Manuel Hüpfel
- Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Str. 1, 76131 Karlsruhe, Germany
| | - Andrei Yu. Kobitski
- Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Str. 1, 76131 Karlsruhe, Germany
| | - Weichun Zhang
- Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Str. 1, 76131 Karlsruhe, Germany
| | - G. Ulrich Nienhaus
- Institute of Applied Physics, Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Str. 1, 76131 Karlsruhe, Germany
- Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
- Institute of Biological and Chemical Systems, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
- Department of Physics, University of Illinois at Urbana-Champaign, 1110 W. Green Street, Urbana, IL 61801, USA
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9
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Barbotin A, Urbančič I, Galiani S, Eggeling C, Booth M, Sezgin E. z-STED Imaging and Spectroscopy to Investigate Nanoscale Membrane Structure and Dynamics. Biophys J 2020; 118:2448-2457. [PMID: 32359408 PMCID: PMC7231928 DOI: 10.1016/j.bpj.2020.04.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 03/12/2020] [Accepted: 04/06/2020] [Indexed: 12/23/2022] Open
Abstract
Super-resolution stimulated emission depletion (STED) microcopy provides optical resolution beyond the diffraction limit. The resolution can be increased laterally (xy) or axially (z). Two-dimensional STED has been extensively used to elucidate the nanoscale membrane structure and dynamics via imaging or combined with spectroscopy techniques such as fluorescence correlation spectroscopy (FCS) and spectral imaging. On the contrary, z-STED has not been used in this context. Here, we show that a combination of z-STED with FCS or spectral imaging enables us to see previously unobservable aspects of cellular membranes. We show that thanks to an axial resolution of ∼100 nm, z-STED can be used to distinguish axially close-by membranes, early endocytic vesicles, or tubular membrane structures. Combination of z-STED with FCS and spectral imaging showed diffusion dynamics and lipid organization in these structures, respectively.
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Affiliation(s)
- Aurélien Barbotin
- Department of Engineering Science, University of Oxford, Oxford, United Kingdom
| | - Iztok Urbančič
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom; Jožef Stefan Institute, Ljubljana, Slovenia
| | - Silvia Galiani
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom; Wolfson Imaging Centre Oxford, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
| | - Christian Eggeling
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom; Wolfson Imaging Centre Oxford, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom; Institute of Applied Optics and Biophysics, Friedrich Schiller University Jena, Jena, Germany; Leibniz Institute of Photonic Technology e.V., Jena, Germany
| | - Martin Booth
- Department of Engineering Science, University of Oxford, Oxford, United Kingdom
| | - Erdinc Sezgin
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom; Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, Solna, Sweden.
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10
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Abstract
STimulated emission depletion (STED) nanoscopy has been proposed to extend greatly our capability of using light to study a variety of biological problems with nanometer-scale resolution. However, in practice the unwanted background noise degrades the STED image quality and precludes quantitative analysis. Here, we discuss the underlying sources of the background noise in STED images, and review current approaches to alleviate this problem, such as time-gating, anti-Stokes excitation removal, and off-focus incomplete depletion suppression. Progress in correcting uncorrelated background photons in fluorescence correlation spectroscopy combined with STED (STED-FCS) will also be discussed.
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Affiliation(s)
- Ye Ma
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States of America
| | - Taekjip Ha
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States of America.,Departments of Biophysics and Biophysical Chemistry, Biophysics, Johns Hopkins University, Baltimore, MD, United States of America.,Howard Hughes Medical Institute, Baltimore, MD, United States of America.,Author to whom any correspondence should be addressed
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11
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Sezgin E, Schneider F, Galiani S, Urbančič I, Waithe D, Lagerholm BC, Eggeling C. Measuring nanoscale diffusion dynamics in cellular membranes with super-resolution STED-FCS. Nat Protoc 2019; 14:1054-1083. [PMID: 30842616 DOI: 10.1038/s41596-019-0127-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 01/04/2019] [Indexed: 11/08/2022]
Abstract
Super-resolution microscopy techniques enable optical imaging in live cells with unprecedented spatial resolution. They unfortunately lack the temporal resolution required to directly investigate cellular dynamics at scales sufficient to measure molecular diffusion. These fast time scales are, on the other hand, routinely accessible by spectroscopic techniques such as fluorescence correlation spectroscopy (FCS). To enable the direct investigation of fast dynamics at the relevant spatial scales, FCS has been combined with super-resolution stimulated emission depletion (STED) microscopy. STED-FCS has been applied in point or scanning mode to reveal nanoscale diffusion behavior of molecules in live cells. In this protocol, we describe the technical details of performing point STED-FCS (pSTED-FCS) and scanning STED-FCS (sSTED-FCS) measurements, from calibration and sample preparation to data acquisition and analysis. We give particular emphasis to 2D diffusion dynamics in cellular membranes, using molecules tagged with organic fluorophores. These measurements can be accomplished within 4-6 h by those proficient in fluorescence imaging.
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Affiliation(s)
- Erdinc Sezgin
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK.
| | - Falk Schneider
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Silvia Galiani
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Iztok Urbančič
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
- Solid State Physics Department, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Dominic Waithe
- Wolfson Imaging Centre, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
- MRC Centre for Computational Biology, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - B Christoffer Lagerholm
- Wolfson Imaging Centre, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Christian Eggeling
- MRC Human Immunology Unit, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK.
- Wolfson Imaging Centre, MRC Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK.
- Institute of Applied Optics, Friedrich-Schiller-University Jena, Jena, Germany.
- Department of Biophysical Imaging, Leibniz Institute of Photonic Technology e.V., Jena, Germany.
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12
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Zheng J, Gao P, Shao X, Nienhaus GU. Refractive index measurement of suspended cells using opposed-view digital holographic microscopy. APPLIED OPTICS 2017; 56:9000-9005. [PMID: 29131185 DOI: 10.1364/ao.56.009000] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 10/13/2017] [Indexed: 06/07/2023]
Abstract
Opposed-view digital holographic microscopy (OV-DHM) with autofocusing and out-of-focus background suppression was demonstrated and applied to measure the refractive index (RI) of suspended HeLa cells. In OV-DHM, a specimen is illuminated from two sides in a 4π-like configuration. The generated two opposite-view object waves, which have orthogonal polarization orientations, interfere with a common reference wave, and the generated holograms are recorded by a CMOS camera. The image plane of the sample was determined by finding the minimal variation between the two object waves. The out-of-focus background was suppressed by averaging the two object waves. Simultaneous determination of both the cell thickness and the phase retardation was avoided by using a spheroidal model for the detached cell obtained from confocal microscopy. Thus, the RI of suspended HeLa cells was measured from phase images of OV-DHM, with the thickness of the cells estimated by using a constant axial-to-lateral ratio. This measurement strategy reveals the RI with an accuracy of ∼10% of the RI difference between cells and surrounding medium.
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13
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Iino R, Iida T, Nakamura A, Saita EI, You H, Sako Y. Single-molecule imaging and manipulation of biomolecular machines and systems. Biochim Biophys Acta Gen Subj 2017; 1862:241-252. [PMID: 28789884 DOI: 10.1016/j.bbagen.2017.08.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 07/23/2017] [Accepted: 08/03/2017] [Indexed: 02/08/2023]
Abstract
BACKGROUND Biological molecular machines support various activities and behaviors of cells, such as energy production, signal transduction, growth, differentiation, and migration. SCOPE OF REVIEW We provide an overview of single-molecule imaging methods involving both small and large probes used to monitor the dynamic motions of molecular machines in vitro (purified proteins) and in living cells, and single-molecule manipulation methods used to measure the forces, mechanical properties and responses of biomolecules. We also introduce several examples of single-molecule analysis, focusing primarily on motor proteins and signal transduction systems. MAJOR CONCLUSIONS Single-molecule analysis is a powerful approach to unveil the operational mechanisms both of individual molecular machines and of systems consisting of many molecular machines. GENERAL SIGNIFICANCE Quantitative, high-resolution single-molecule analyses of biomolecular systems at the various hierarchies of life will help to answer our fundamental question: "What is life?" This article is part of a Special Issue entitled "Biophysical Exploration of Dynamical Ordering of Biomolecular Systems" edited by Dr. Koichi Kato.
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Affiliation(s)
- Ryota Iino
- Okazaki Institute for Integrative Bioscience, Institute for Molecular Science, National Institutes of Natural Sciences, Japan; Department of Functional Molecular Science, School of Physical Sciences, The Graduate University for Advanced Studies (SOKENDAI), Japan.
| | - Tatsuya Iida
- Okazaki Institute for Integrative Bioscience, Institute for Molecular Science, National Institutes of Natural Sciences, Japan; Department of Functional Molecular Science, School of Physical Sciences, The Graduate University for Advanced Studies (SOKENDAI), Japan
| | - Akihiko Nakamura
- Okazaki Institute for Integrative Bioscience, Institute for Molecular Science, National Institutes of Natural Sciences, Japan; Department of Functional Molecular Science, School of Physical Sciences, The Graduate University for Advanced Studies (SOKENDAI), Japan
| | - Ei-Ichiro Saita
- Information Processing Biology Unit, Okinawa Institute of Science and Technology Graduate University, Japan
| | - Huijuan You
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, China.
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