1
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Herkert EK, Lau L, Pons Lanau R, Garcia-Parajo MF. Hexagonal Plasmonic Arrays for High-Throughput Multicolor Single-Molecule Studies. ACS APPLIED MATERIALS & INTERFACES 2024. [PMID: 39041362 DOI: 10.1021/acsami.4c04744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/24/2024]
Abstract
Nanophotonic biosensors offer exceptional sensitivity in the presence of strong background signals by enhancing and confining light in subwavelength volumes. In the field of nanophotonic biosensors, antenna-in-box (AiB) designs consisting of a nanoantenna within a nanoaperture have demonstrated remarkable single-molecule fluorescence detection sensitivities under physiologically relevant conditions. However, their full potential has not yet been exploited as current designs prohibit insightful correlative multicolor single-molecule studies and are limited in terms of throughput. Here, we overcome these constraints by introducing aluminum-based hexagonal close-packed AiB (HCP-AiB) arrays. Our approach enables the parallel readout of over 1000 HCP-AiBs with multicolor single-molecule sensitivity up to micromolar concentrations using an alternating three-color excitation scheme and epi-fluorescence detection. Notably, the high-density HCP-AiB arrays not only enable high-throughput studies at micromolar concentrations but also offer high single-molecule detection probabilities in the nanomolar range. We demonstrate that robust and alignment-free correlative multicolor studies are possible using optical fiducial markers even when imaging in the low millisecond range. These advancements pave the way for the use of HCP-AiB arrays as biosensor architectures for high-throughput multicolor studies on single-molecule dynamics.
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Affiliation(s)
- Ediz Kaan Herkert
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
| | - Lukas Lau
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
| | - Roger Pons Lanau
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
| | - Maria F Garcia-Parajo
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
- ICREA, 08010 Barcelona, Spain
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2
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Nüesch MF, Pietrek L, Holmstrom ED, Nettels D, von Roten V, Kronenberg-Tenga R, Medalia O, Hummer G, Schuler B. Nanosecond chain dynamics of single-stranded nucleic acids. Nat Commun 2024; 15:6010. [PMID: 39019880 PMCID: PMC11255343 DOI: 10.1038/s41467-024-50092-8] [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: 01/26/2024] [Accepted: 07/01/2024] [Indexed: 07/19/2024] Open
Abstract
The conformational dynamics of single-stranded nucleic acids are fundamental for nucleic acid folding and function. However, their elementary chain dynamics have been difficult to resolve experimentally. Here we employ a combination of single-molecule Förster resonance energy transfer, nanosecond fluorescence correlation spectroscopy, and nanophotonic enhancement to determine the conformational ensembles and rapid chain dynamics of short single-stranded nucleic acids in solution. To interpret the experimental results in terms of end-to-end distance dynamics, we utilize the hierarchical chain growth approach, simple polymer models, and refinement with Bayesian inference to generate structural ensembles that closely align with the experimental data. The resulting chain reconfiguration times are exceedingly rapid, in the 10-ns range. Solvent viscosity-dependent measurements indicate that these dynamics of single-stranded nucleic acids exhibit negligible internal friction and are thus dominated by solvent friction. Our results provide a detailed view of the conformational distributions and rapid dynamics of single-stranded nucleic acids.
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Affiliation(s)
- Mark F Nüesch
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Lisa Pietrek
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438, Frankfurt am Main, Germany
| | - Erik D Holmstrom
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
- Department of Chemistry, University of Kansas, Lawrence, KS, USA.
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS, USA.
| | - Daniel Nettels
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Valentin von Roten
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Rafael Kronenberg-Tenga
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Ohad Medalia
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438, Frankfurt am Main, Germany.
- Institute for Biophysics, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany.
| | - Benjamin Schuler
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
- Department of Physics, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
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3
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Roy P, Zhu S, Claude JB, Liu J, Wenger J. Ultraviolet Resonant Nanogap Antennas with Rhodium Nanocube Dimers for Enhancing Protein Intrinsic Autofluorescence. ACS NANO 2023; 17:22418-22429. [PMID: 37931219 PMCID: PMC10690780 DOI: 10.1021/acsnano.3c05008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Accepted: 09/07/2023] [Indexed: 11/08/2023]
Abstract
Plasmonic optical nanoantennas offer compelling solutions for enhancing light-matter interactions at the nanoscale. However, until now, their focus has been mainly limited to the visible and near-infrared regions, overlooking the immense potential of the ultraviolet (UV) range, where molecules exhibit their strongest absorption. Here, we present the realization of UV resonant nanogap antennas constructed from paired rhodium nanocubes. Rhodium emerges as a robust alternative to aluminum, offering enhanced stability in wet environments and ensuring reliable performance in the UV range. Our results showcase the nanoantenna's ability to enhance the UV autofluorescence of label-free streptavidin and hemoglobin proteins. We achieve significant enhancements of the autofluorescence brightness per protein by up to 120-fold and reach zeptoliter detection volumes, enabling UV autofluorescence correlation spectroscopy (UV-FCS) at high concentrations of several tens of micromolar. We investigate the modulation of fluorescence photokinetic rates and report excellent agreement between the experimental results and numerical simulations. This work expands the applicability of plasmonic nanoantennas to the deep UV range, unlocking the investigation of label-free proteins at physiological concentrations.
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Affiliation(s)
- Prithu Roy
- Aix
Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, AMUTech, 13013 Marseille, France
| | - Siyuan Zhu
- Department
of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Jean-Benoît Claude
- Aix
Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, AMUTech, 13013 Marseille, France
| | - Jie Liu
- Department
of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Jérôme Wenger
- Aix
Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, AMUTech, 13013 Marseille, France
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4
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Roy P, Claude JB, Tiwari S, Barulin A, Wenger J. Ultraviolet Nanophotonics Enables Autofluorescence Correlation Spectroscopy on Label-Free Proteins with a Single Tryptophan. NANO LETTERS 2023; 23:497-504. [PMID: 36603115 DOI: 10.1021/acs.nanolett.2c03797] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Using the ultraviolet autofluorescence of tryptophan amino acids offers fascinating perspectives to study single proteins without the drawbacks of fluorescence labeling. However, the low autofluorescence signals have so far limited the UV detection to large proteins containing several tens of tryptophan residues. This limit is not compatible with the vast majority of proteins which contain only a few tryptophans. Here we push the sensitivity of label-free ultraviolet fluorescence correlation spectroscopy (UV-FCS) down to the single tryptophan level. Our results show how the combination of nanophotonic plasmonic antennas, antioxidants, and background reduction techniques can improve the signal-to-background ratio by over an order of magnitude and enable UV-FCS on thermonuclease proteins with a single tryptophan residue. This sensitivity breakthrough unlocks the applicability of UV-FCS technique to a broad library of label-free proteins.
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Affiliation(s)
- Prithu Roy
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, AMUTech, 13013 Marseille, France
| | - Jean-Benoît Claude
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, AMUTech, 13013 Marseille, France
| | - Sunny Tiwari
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, AMUTech, 13013 Marseille, France
| | - Aleksandr Barulin
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, AMUTech, 13013 Marseille, France
| | - Jérôme Wenger
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, AMUTech, 13013 Marseille, France
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5
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Messina TC, Srijanto BR, Collier CP, Kravchenko II, Richards CI. Gold Ion Beam Milled Gold Zero-Mode Waveguides. NANOMATERIALS 2022; 12:nano12101755. [PMID: 35630978 PMCID: PMC9147361 DOI: 10.3390/nano12101755] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 05/13/2022] [Accepted: 05/17/2022] [Indexed: 12/02/2022]
Abstract
Zero-mode waveguides (ZMWs) are widely used in single molecule fluorescence microscopy for their enhancement of emitted light and the ability to study samples at physiological concentrations. ZMWs are typically produced using photo or electron beam lithography. We report a new method of ZMW production using focused ion beam (FIB) milling with gold ions. We demonstrate that ion-milled gold ZMWs with 200 nm apertures exhibit similar plasmon-enhanced fluorescence seen with ZMWs fabricated with traditional techniques such as electron beam lithography.
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Affiliation(s)
- Troy C. Messina
- Department of Physics, Berea College, 101 Chestnut Street, Berea, KY 40404, USA
- Correspondence: ; Tel.: +1-859-985-3326
| | - Bernadeta R. Srijanto
- Center for Nanophase Materials Science, Oak Ridge National Labs, Oak Ridge, TN 37831, USA; (B.R.S.); (C.P.C.); (I.I.K.)
| | - Charles Patrick Collier
- Center for Nanophase Materials Science, Oak Ridge National Labs, Oak Ridge, TN 37831, USA; (B.R.S.); (C.P.C.); (I.I.K.)
| | - Ivan I. Kravchenko
- Center for Nanophase Materials Science, Oak Ridge National Labs, Oak Ridge, TN 37831, USA; (B.R.S.); (C.P.C.); (I.I.K.)
| | - Christopher I. Richards
- Department of Chemistry, University of Kentucky, 209 Chemistry-Physics Building, Lexington, KY 40202, USA;
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6
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Konoplev G, Agafonova D, Bakhchova L, Mukhin N, Kurachkina M, Schmidt MP, Verlov N, Sidorov A, Oseev A, Stepanova O, Kozyrev A, Dmitriev A, Hirsch S. Label-Free Physical Techniques and Methodologies for Proteins Detection in Microfluidic Biosensor Structures. Biomedicines 2022; 10:207. [PMID: 35203416 PMCID: PMC8868674 DOI: 10.3390/biomedicines10020207] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 01/01/2022] [Accepted: 01/11/2022] [Indexed: 12/25/2022] Open
Abstract
Proteins in biological fluids (blood, urine, cerebrospinal fluid) are important biomarkers of various pathological conditions. Protein biomarkers detection and quantification have been proven to be an indispensable diagnostic tool in clinical practice. There is a growing tendency towards using portable diagnostic biosensor devices for point-of-care (POC) analysis based on microfluidic technology as an alternative to conventional laboratory protein assays. In contrast to universally accepted analytical methods involving protein labeling, label-free approaches often allow the development of biosensors with minimal requirements for sample preparation by omitting expensive labelling reagents. The aim of the present work is to review the variety of physical label-free techniques of protein detection and characterization which are suitable for application in micro-fluidic structures and analyze the technological and material aspects of label-free biosensors that implement these methods. The most widely used optical and impedance spectroscopy techniques: absorption, fluorescence, surface plasmon resonance, Raman scattering, and interferometry, as well as new trends in photonics are reviewed. The challenges of materials selection, surfaces tailoring in microfluidic structures, and enhancement of the sensitivity and miniaturization of biosensor systems are discussed. The review provides an overview for current advances and future trends in microfluidics integrated technologies for label-free protein biomarkers detection and discusses existing challenges and a way towards novel solutions.
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Affiliation(s)
- Georgii Konoplev
- Faculty of Electronics, Saint Petersburg Electrotechnical University “LETI”, 197376 Saint Petersburg, Russia; (D.A.); (A.S.); (O.S.); (A.K.)
| | - Darina Agafonova
- Faculty of Electronics, Saint Petersburg Electrotechnical University “LETI”, 197376 Saint Petersburg, Russia; (D.A.); (A.S.); (O.S.); (A.K.)
| | - Liubov Bakhchova
- Institute for Automation Technology, Otto-von-Guericke-University Magdeburg, 39106 Magdeburg, Germany;
| | - Nikolay Mukhin
- Faculty of Electronics, Saint Petersburg Electrotechnical University “LETI”, 197376 Saint Petersburg, Russia; (D.A.); (A.S.); (O.S.); (A.K.)
- Department of Engineering, University of Applied Sciences Brandenburg, 14770 Brandenburg an der Havel, Germany; (M.K.); (S.H.)
| | - Marharyta Kurachkina
- Department of Engineering, University of Applied Sciences Brandenburg, 14770 Brandenburg an der Havel, Germany; (M.K.); (S.H.)
| | - Marc-Peter Schmidt
- Faculty of Electrical Engineering, University of Applied Sciences Dresden, 01069 Dresden, Germany;
| | - Nikolay Verlov
- Molecular and Radiation Biophysics Division, Petersburg Nuclear Physics Institute Named by B.P. Konstantinov, National Research Centre Kurchatov Institute, 188300 Gatchina, Russia;
| | - Alexander Sidorov
- Faculty of Electronics, Saint Petersburg Electrotechnical University “LETI”, 197376 Saint Petersburg, Russia; (D.A.); (A.S.); (O.S.); (A.K.)
- Fuculty of Photonics, ITMO University, 197101 Saint Petersburg, Russia
| | - Aleksandr Oseev
- FEMTO-ST Institute, CNRS UMR-6174, University Bourgogne Franche-Comté, 25000 Besançon, France;
| | - Oksana Stepanova
- Faculty of Electronics, Saint Petersburg Electrotechnical University “LETI”, 197376 Saint Petersburg, Russia; (D.A.); (A.S.); (O.S.); (A.K.)
| | - Andrey Kozyrev
- Faculty of Electronics, Saint Petersburg Electrotechnical University “LETI”, 197376 Saint Petersburg, Russia; (D.A.); (A.S.); (O.S.); (A.K.)
| | - Alexander Dmitriev
- Department of Ecological Physiology, Federal State Budgetary Scientific Institution “Institute of Experimental Medicine” (FSBSI “IEM”), 197376 Saint Petersburg, Russia;
| | - Soeren Hirsch
- Department of Engineering, University of Applied Sciences Brandenburg, 14770 Brandenburg an der Havel, Germany; (M.K.); (S.H.)
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7
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Iizuka R, Yamazaki H, Uemura S. Zero-mode waveguides and nanopore-based sequencing technologies accelerate single-molecule studies. Biophys Physicobiol 2022; 19:e190032. [DOI: 10.2142/biophysico.bppb-v19.0032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 08/26/2022] [Indexed: 12/01/2022] Open
Affiliation(s)
- Ryo Iizuka
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo
| | - Hirohito Yamazaki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo
| | - Sotaro Uemura
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo
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8
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Maccaferri N, Barbillon G, Koya AN, Lu G, Acuna GP, Garoli D. Recent advances in plasmonic nanocavities for single-molecule spectroscopy. NANOSCALE ADVANCES 2021; 3:633-642. [PMID: 36133836 PMCID: PMC9418431 DOI: 10.1039/d0na00715c] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 11/04/2020] [Indexed: 05/12/2023]
Abstract
Plasmonic nanocavities are able to engineer and confine electromagnetic fields to subwavelength volumes. In the past decade, they have enabled a large set of applications, in particular for sensing, optical trapping, and the investigation of physical and chemical phenomena at a few or single-molecule levels. This extreme sensitivity is possible thanks to the highly confined local field intensity enhancement, which depends on the geometry of plasmonic nanocavities. Indeed, suitably designed structures providing engineered local optical fields lead to enhanced optical sensing based on different phenomena such as surface enhanced Raman scattering, fluorescence, and Förster resonance energy transfer. In this mini-review, we illustrate the most recent results on plasmonic nanocavities, with specific emphasis on the detection of single molecules.
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Affiliation(s)
- Nicolò Maccaferri
- Department of Physics and Materials Science, University of Luxembourg 162a avenue de la Faïencerie L-1511 Luxembourg Luxembourg
| | | | | | - Guowei Lu
- State Key Laboratory for Mesoscopic Physics, Collaborative Innovation Center of Quantum Matter, Peking University Beijing 100871 China
| | - Guillermo P Acuna
- Département de Physique - Photonic Nanosystems, Université de Fribourg CH-1700 Fribourg Switzerland
| | - Denis Garoli
- Istituto Italiano di Tecnologia Via Morego 30 16163 Genova Italy
- Faculty of Science and Technology, Free University of Bozen-Bolzano Piazza università 1 39100 Bolzano Italy
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9
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Baibakov M, Barulin A, Roy P, Claude JB, Patra S, Wenger J. Zero-mode waveguides can be made better: fluorescence enhancement with rectangular aluminum nanoapertures from the visible to the deep ultraviolet. NANOSCALE ADVANCES 2020; 2:4153-4160. [PMID: 36132755 PMCID: PMC9417158 DOI: 10.1039/d0na00366b] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 07/20/2020] [Indexed: 05/25/2023]
Abstract
Nanoapertures milled in metallic films called zero-mode waveguides (ZMWs) overcome the limitations of classical confocal microscopes by enabling single molecule analysis at micromolar concentrations with improved fluorescence brightness. While the ZMWs have found many applications in single molecule fluorescence studies, their shape has been mainly limited to be circular. Owing to the large parameter space to explore and the lack of guidelines, earlier attempts using more elaborate shapes have led to unclear conclusions whether or not the performance was improved as compared to a circular ZMW. Here, we comparatively analyze the performance of rectangular-shaped nanoapertures milled in aluminum to enhance the fluorescence emission rate of single molecules from the near infrared to the deep ultraviolet. Our new design is based on rational principles taking maximum advantage of the laser linear polarization. While the long edge of the nanorectangle is set to meet the cut-off size for the propagation of light into the nanoaperture, the short edge is reduced to 30 nm to accelerate the photodynamics while maintaining bright fluorescence rates. Our results show that both in the red and in the ultraviolet, the nanorectangles provide 50% brighter photon count rates as compared to the best performing circular ZMWs and achieve fluorescence lifetimes shorter than 300 ps. These findings can be readily used to improve the performance of ZMWs, especially for fast biomolecular dynamics, bright single-photon sources, and ultraviolet plasmonics.
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Affiliation(s)
- Mikhail Baibakov
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel 13013 Marseille France
| | - Aleksandr Barulin
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel 13013 Marseille France
| | - Prithu Roy
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel 13013 Marseille France
| | - Jean-Benoît Claude
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel 13013 Marseille France
| | - Satyajit Patra
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel 13013 Marseille France
| | - Jérôme Wenger
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel 13013 Marseille France
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10
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Amodeo R, Convertino D, Calvello M, Ceccarelli L, Bonsignore F, Ravelli C, Cattaneo A, Martini C, Luin S, Mitola S, Signore G, Marchetti L. Fluorolabeling of the PPTase-Related Chemical Tags: Comparative Study of Different Membrane Receptors and Different Fluorophores in the Labeling Reactions. Front Mol Biosci 2020; 7:195. [PMID: 32850976 PMCID: PMC7426934 DOI: 10.3389/fmolb.2020.00195] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 07/22/2020] [Indexed: 11/13/2022] Open
Abstract
The set-up of an advanced imaging experiment requires a careful selection of suitable labeling strategies and fluorophores for the tagging of the molecules of interest. Here we provide an experimental workflow to allow evaluation of fluorolabeling performance of the chemical tags target of phosphopantetheinyl transferase enzymes (PPTases), once inserted in the sequence of different proteins of interest. First, S6 peptide tag was fused to three different single-pass transmembrane proteins (the tyrosine receptor kinases TrkA and VEGFR2 and the tumor necrosis factor receptor p75NTR), providing evidence that all of them can be conveniently albeit differently labeled. Moreover, we chose the S6-tagged TrkA construct to test eight different organic fluorophores for the PPTase labeling of membrane receptors in living cells. We systematically compared their non-specific internalization when added to a S6-tag negative cell culture, the percentage of S6-TrkA expressing cells effectively labeled and the relative mean fluorescence intensity, their photostability upon conjugation, and ratio of specific (cellular) versus background (glass-adhered) signal. This allowed to identify which fluorophores are actually recommended for these labeling reactions. Finally, we compared the PPTase labeling of a purified, YBBR-tagged Nerve Growth Factor with two differently charged organic dyes. We detected some batch-to-batch variability in the labeling yield, regardless of the fluorophore used. However, upon purification of the fluorescent species and incubation with living primary DRG neurons, no significant difference could be appreciated in both internalization and axonal transport of the labeled neurotrophins.
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Affiliation(s)
- Rosy Amodeo
- NEST, Scuola Normale Superiore, Pisa, Italy.,Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, Pisa, Italy
| | - Domenica Convertino
- NEST, Scuola Normale Superiore, Pisa, Italy.,Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, Pisa, Italy
| | | | - Lorenzo Ceccarelli
- Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, Pisa, Italy.,Dipartimento di Farmacia, Università di Pisa, Pisa, Italy
| | | | - Cosetta Ravelli
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | | | | | - Stefano Luin
- NEST, Scuola Normale Superiore, Pisa, Italy.,CNR-NANO, Pisa, Italy
| | - Stefania Mitola
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Giovanni Signore
- NEST, Scuola Normale Superiore, Pisa, Italy.,Fondazione Pisana per la Scienza Onlus, Pisa, Italy
| | - Laura Marchetti
- Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, Pisa, Italy.,Dipartimento di Farmacia, Università di Pisa, Pisa, Italy
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11
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Baibakov M, Patra S, Claude JB, Wenger J. Long-Range Single-Molecule Förster Resonance Energy Transfer between Alexa Dyes in Zero-Mode Waveguides. ACS OMEGA 2020; 5:6947-6955. [PMID: 32258931 PMCID: PMC7114734 DOI: 10.1021/acsomega.0c00322] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 03/05/2020] [Indexed: 06/11/2023]
Abstract
Zero-mode waveguide (ZMW) nano-apertures milled in metal films were proposed to improve the Förster resonance energy transfer (FRET) efficiency and enable single-molecule FRET detection beyond the 10 nm barrier, overcoming the restrictions of diffraction-limited detection in a homogeneous medium. However, the earlier ZMW demonstrations were limited to the Atto 550-Atto 647N fluorophore pair, asking the question whether the FRET enhancement observation was an artifact related to this specific set of fluorescent dyes. Here, we use Alexa Fluor 546 and Alexa Fluor 647 to investigate single-molecule FRET at large donor-acceptor separations exceeding 10 nm inside ZMWs. These Alexa fluorescent dyes feature a markedly different chemical structure, surface charge, and hydrophobicity as compared to their Atto counterparts. Our single molecule data on Alexa 546-Alexa 647 demonstrate enhanced FRET efficiencies at large separations exceeding 10 nm, extending the spatial range available for FRET and confirming the earlier conclusions. By showing that the FRET enhancement inside a ZMW does not depend on the set of fluorescent dyes, this report is an important step to establish the relevance of ZMWs to extend the sensitivity and detection range of FRET, while preserving its ability to work on regular fluorescent dye pairs.
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Affiliation(s)
- Mikhail Baibakov
- Aix Marseille Univ, CNRS, Centrale
Marseille, Institut Fresnel, 13013 Marseille, France
| | - Satyajit Patra
- Aix Marseille Univ, CNRS, Centrale
Marseille, Institut Fresnel, 13013 Marseille, France
| | - Jean-Benoît Claude
- Aix Marseille Univ, CNRS, Centrale
Marseille, Institut Fresnel, 13013 Marseille, France
| | - Jérôme Wenger
- Aix Marseille Univ, CNRS, Centrale
Marseille, Institut Fresnel, 13013 Marseille, France
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