1
|
El Arawi D, Vézy C, Déturche R, Lehmann M, Kessler H, Dontenwill M, Jaffiol R. Advanced quantification for single-cell adhesion by variable-angle TIRF nanoscopy. BIOPHYSICAL REPORTS 2021; 1:100021. [PMID: 36425460 PMCID: PMC9680782 DOI: 10.1016/j.bpr.2021.100021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 09/07/2021] [Indexed: 05/25/2023]
Abstract
Over the last decades, several techniques have been developed to study cell adhesion; however, they present significant shortcomings. Such techniques mostly focus on strong adhesion related to specific protein-protein associations, such as ligand-receptor binding in focal adhesions. Therefore, weak adhesion, related to less specific or nonspecific cell-substrate interactions, are rarely addressed. Hence, we propose in this work a complete investigation of cell adhesion, from highly specific to nonspecific adhesiveness, using variable-angle total internal reflection fluorescence (vaTIRF) nanoscopy. This technique allows us to map in real time cell topography with a nanometric axial resolution, along with cell cortex refractive index. These two key parameters allow us to distinguish high and low adhesive cell-substrate contacts. Furthermore, vaTIRF provides cell-substrate binding energy, thus revealing a correlation between cell contractility and cell-substrate binding energy. Here, we highlight the quantitative measurements achieved by vaTIRF on U87MG glioma cells expressing different amounts of α 5 integrins and distinct motility on fibronectin. Regarding integrin expression level, data extracted from vaTIRF measurements, such as the number and size of high adhesive contacts per cell, corroborate the adhesiveness of U87MG cells as intended. Interestingly enough, we found that cells overexpressing α 5 integrins present a higher contractility and lower adhesion energy.
Collapse
Affiliation(s)
- Dalia El Arawi
- Light, nanomaterials, nanotechnologies, ERL CNRS 7004, Université de Technologie de Troyes, Troyes, France
| | - Cyrille Vézy
- Light, nanomaterials, nanotechnologies, ERL CNRS 7004, Université de Technologie de Troyes, Troyes, France
| | - Régis Déturche
- Light, nanomaterials, nanotechnologies, ERL CNRS 7004, Université de Technologie de Troyes, Troyes, France
| | - Maxime Lehmann
- Laboratoire de Bioimagerie et Pathologies, UMR CNRS 7021, Université de Strasbourg, Faculté de Pharmacie, Illkirch, France
| | - Horst Kessler
- Department Chemie, Institute for Advanced Study, Technische Universität München, Garching, Germany
| | - Monique Dontenwill
- Laboratoire de Bioimagerie et Pathologies, UMR CNRS 7021, Université de Strasbourg, Faculté de Pharmacie, Illkirch, France
| | - Rodolphe Jaffiol
- Light, nanomaterials, nanotechnologies, ERL CNRS 7004, Université de Technologie de Troyes, Troyes, France
| |
Collapse
|
2
|
Oheim M, Salomon A, Brunstein M. Supercritical Angle Fluorescence Microscopy and Spectroscopy. Biophys J 2020; 118:2339-2348. [PMID: 32348720 PMCID: PMC7231923 DOI: 10.1016/j.bpj.2020.03.029] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 03/13/2020] [Accepted: 03/23/2020] [Indexed: 01/06/2023] Open
Abstract
Fluorescence detection, either involving propagating or near-field emission, is widely being used in spectroscopy, sensing, and microscopy. Total internal reflection fluorescence (TIRF) confines fluorescence excitation by an evanescent (near) field, and it is a popular contrast generator for surface-selective fluorescence assays. Its emission equivalent, supercritical angle fluorescence (SAF), is comparably less established, although it achieves a similar optical sectioning as TIRF does. SAF emerges when a fluorescing molecule is located very close to an interface and its near-field emission couples to the higher refractive index medium (n2 >n1) and becomes propagative. Then, most fluorescence is detectable on the side of the higher-index substrate, and a large fraction of this fluorescence is emitted into angles forbidden by Snell's law. SAF, as well as the undercritical angle fluorescence (UAF; far-field emission) components, can be collected with microscope objectives having a high-enough detection aperture (numerical aperture >n2) and be separated in the back focal plane by Fourier filtering. The back focal plane image encodes information about the fluorophore radiation pattern, and it can be analyzed to yield precise information about the refractive index in which the emitters are embedded, their nanometric distance from the interface, and their orientation. A SAF microscope can retrieve this near-field information through wide-field optics in a spatially resolved manner, and this functionality can be added to an existing inverted microscope. Here, we describe the potential underpinning of SAF microscopy and spectroscopy, particularly in comparison with TIRF. We review the challenges and opportunities that SAF presents from a biophysical perspective, and we discuss areas in which we see potential.
Collapse
Affiliation(s)
- Martin Oheim
- Saints-Pères Paris Institute for the Neurosciences, Université de Paris, CNRS, Paris, France.
| | - Adi Salomon
- Saints-Pères Paris Institute for the Neurosciences, Université de Paris, CNRS, Paris, France; Department of Chemistry, Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan, Israel
| | - Maia Brunstein
- Saints-Pères Paris Institute for the Neurosciences, Université de Paris, CNRS, Paris, France; Chaire d'Excellence Junior, Université Sorbonne Paris Cité, Paris, France
| |
Collapse
|
3
|
Weissman A, Klimovsky H, Harel D, Ron R, Oheim M, Salomon A. Fabrication of Dipole-Aligned Thin Films of Porphyrin J-Aggregates over Large Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:844-851. [PMID: 31912741 DOI: 10.1021/acs.langmuir.9b02754] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We report a new approach for large-scale alignment of micron-sized J-aggregates of a derivative of porphyrin onto planar glass substrates. We applied a unidirectional nitrogen flow to an aqueous dye drop deposited onto a glass substrate to form an about 5 nm thick film of aligned J-aggregates over macroscopic surface areas up to several millimeters. The inter-aggregate distance is ∼500 nm, and it scales with the nitrogen pressure. We verified the film thickness and J-aggregate alignment using multimodal microscopy and spectroscopy techniques. Our technique is fast, simple, and cost-effective for producing large two-dimensional (2-D) arrays of aligned emitters.
Collapse
Affiliation(s)
- Adam Weissman
- Department of Chemistry, Institute of Nanotechnology and Advanced Materials (BINA) , Bar-Ilan University , Ramat-Gan 5290002 , Israel
| | - Hodaya Klimovsky
- Department of Chemistry, Institute of Nanotechnology and Advanced Materials (BINA) , Bar-Ilan University , Ramat-Gan 5290002 , Israel
| | - Dor Harel
- Department of Chemistry, Institute of Nanotechnology and Advanced Materials (BINA) , Bar-Ilan University , Ramat-Gan 5290002 , Israel
| | - Racheli Ron
- Department of Chemistry, Institute of Nanotechnology and Advanced Materials (BINA) , Bar-Ilan University , Ramat-Gan 5290002 , Israel
| | - Martin Oheim
- Université de Paris, SPPIN - Saints-Pères Paris Institute for the Neurosciences, CNRS , F-75006 Paris , France
| | - Adi Salomon
- Department of Chemistry, Institute of Nanotechnology and Advanced Materials (BINA) , Bar-Ilan University , Ramat-Gan 5290002 , Israel
| |
Collapse
|
4
|
Oheim M, Salomon A, Weissman A, Brunstein M, Becherer U. Calibrating Evanescent-Wave Penetration Depths for Biological TIRF Microscopy. Biophys J 2019; 117:795-809. [PMID: 31439287 DOI: 10.1016/j.bpj.2019.07.048] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 07/08/2019] [Accepted: 07/23/2019] [Indexed: 11/28/2022] Open
Abstract
Roughly half of a cell's proteins are located at or near the plasma membrane. In this restricted space, the cell senses its environment, signals to its neighbors, and exchanges cargo through exo- and endocytotic mechanisms. Ligands bind to receptors, ions flow across channel pores, and transmitters and metabolites are transported against concentration gradients. Receptors, ion channels, pumps, and transporters are the molecular substrates of these biological processes, and they constitute important targets for drug discovery. Total internal reflection fluorescence (TIRF) microscopy suppresses the background from the cell's deeper layers and provides contrast for selectively imaging dynamic processes near the basal membrane of live cells. The optical sectioning of TIRF is based on the excitation confinement of the evanescent wave generated at the glass/cell interface. How deep the excitation light actually penetrates the sample is difficult to know, making the quantitative interpretation of TIRF data problematic. Nevertheless, many applications like superresolution microscopy, colocalization, Förster resonance energy transfer, near-membrane fluorescence recovery after photobleaching, uncaging or photoactivation/switching as well as single-particle tracking require the quantitative interpretation of evanescent-wave-excited images. Here, we review existing techniques for characterizing evanescent fields, and we provide a roadmap for comparing TIRF data across images, experiments, and laboratories.
Collapse
Affiliation(s)
- Martin Oheim
- Université de Paris, CNRS, Saints-Pères Paris Institute for the Neurosciences (SPPIN), Paris, France.
| | - Adi Salomon
- Department of Chemistry, Institute of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat Gan, Israel
| | - Adam Weissman
- Department of Chemistry, Institute of Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat Gan, Israel
| | - Maia Brunstein
- Université de Paris, CNRS, Saints-Pères Paris Institute for the Neurosciences (SPPIN), Paris, France; Chaire d'Excellence Junior, Université Sorbonne Paris Cité, Paris, France
| | - Ute Becherer
- Saarland University, Department of Physiology, CIPMM, Homburg/Saar, Germany
| |
Collapse
|