1
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Wang L, Zang P, Li J, Zhang Z, Li C, Zheng A, Zhao S, Yao J, Li C, Guo Z, Zhang W, Zhou L. Single Effective Complex Loading into Zero-Mode Waveguides Optimized with Fluorescence Evaluation at Quenching and Accumulation Checkpoints. ACS APPLIED MATERIALS & INTERFACES 2024; 16:25676-25685. [PMID: 38742765 DOI: 10.1021/acsami.4c01836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Single-molecule detection with high accuracy and specialty plays an important role in biomedical diagnosis and screening. Zero-mode waveguides (ZMWs) enable the possibility of single biological molecule detection in real time. Nevertheless, the absence of a reliable assessment for single effective complex loading has constrained further applications of ZMWs in complex interaction. Both the quantity and activity of the complex loaded into ZMWs have a critical effect on the efficiency of detection. Herein, a fluorescence evaluation at quenching and accumulation checkpoints was established to assess and optimize single effective complex loading into ZMWs. A primer-template-enzyme ternary complex was designed, and then an evaluation for quantity statistics at the quenching checkpoint and functional activity at the accumulation checkpoint was used to validate the effectiveness of complexes loaded into ZMWs. By optimizing the parameters such as loading time, procedures, and enzyme amount, the single-molecule effective occupancy was increased to 25.48%, achieving 68.86% of the theoretical maximum value (37%) according to Poisson statistics. It is of great significance to provide effective complex-loading validation for improving the sample-loading efficiency of single-molecule assays or sequencing in the future.
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Affiliation(s)
- Lu Wang
- School of Biomedical Engineering (Suzhou), Division of Life Sciences and Medicine, University of Science and Technology of China, 230026 Hefei, China
- CAS Key Lab of Bio-Medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, 215163 Suzhou, China
| | - Peilin Zang
- School of Biomedical Engineering (Suzhou), Division of Life Sciences and Medicine, University of Science and Technology of China, 230026 Hefei, China
- CAS Key Lab of Bio-Medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, 215163 Suzhou, China
| | - Jinze Li
- School of Biomedical Engineering (Suzhou), Division of Life Sciences and Medicine, University of Science and Technology of China, 230026 Hefei, China
- CAS Key Lab of Bio-Medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, 215163 Suzhou, China
| | - Zhiqi Zhang
- School of Biomedical Engineering (Suzhou), Division of Life Sciences and Medicine, University of Science and Technology of China, 230026 Hefei, China
- CAS Key Lab of Bio-Medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, 215163 Suzhou, China
| | - Chao Li
- School of Biomedical Engineering (Suzhou), Division of Life Sciences and Medicine, University of Science and Technology of China, 230026 Hefei, China
- CAS Key Lab of Bio-Medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, 215163 Suzhou, China
| | - Anran Zheng
- CAS Key Lab of Bio-Medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, 215163 Suzhou, China
| | - Shasha Zhao
- CAS Key Lab of Bio-Medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, 215163 Suzhou, China
| | - Jia Yao
- School of Biomedical Engineering (Suzhou), Division of Life Sciences and Medicine, University of Science and Technology of China, 230026 Hefei, China
- CAS Key Lab of Bio-Medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, 215163 Suzhou, China
| | - Chuanyu Li
- School of Biomedical Engineering (Suzhou), Division of Life Sciences and Medicine, University of Science and Technology of China, 230026 Hefei, China
- CAS Key Lab of Bio-Medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, 215163 Suzhou, China
| | - Zhen Guo
- School of Biomedical Engineering (Suzhou), Division of Life Sciences and Medicine, University of Science and Technology of China, 230026 Hefei, China
- CAS Key Lab of Bio-Medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, 215163 Suzhou, China
| | - Wei Zhang
- School of Biomedical Engineering (Suzhou), Division of Life Sciences and Medicine, University of Science and Technology of China, 230026 Hefei, China
- CAS Key Lab of Bio-Medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, 215163 Suzhou, China
- Ji Hua Laboratory, 528200 Foshan, China
| | - Lianqun Zhou
- School of Biomedical Engineering (Suzhou), Division of Life Sciences and Medicine, University of Science and Technology of China, 230026 Hefei, China
- CAS Key Lab of Bio-Medical Diagnostics, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, 215163 Suzhou, China
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2
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White D, Smith MA, Chanda B, Goldsmith RH. Strategies for Overcoming the Single-Molecule Concentration Barrier. ACS MEASUREMENT SCIENCE AU 2023; 3:239-257. [PMID: 37600457 PMCID: PMC10436376 DOI: 10.1021/acsmeasuresciau.3c00002] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 04/21/2023] [Accepted: 04/24/2023] [Indexed: 08/22/2023]
Abstract
Fluorescence-based single-molecule approaches have helped revolutionize our understanding of chemical and biological mechanisms. Unfortunately, these methods are only suitable at low concentrations of fluorescent molecules so that single fluorescent species of interest can be successfully resolved beyond background signal. The application of these techniques has therefore been limited to high-affinity interactions despite most biological and chemical processes occurring at much higher reactant concentrations. Fortunately, recent methodological advances have demonstrated that this concentration barrier can indeed be broken, with techniques reaching concentrations as high as 1 mM. The goal of this Review is to discuss the challenges in performing single-molecule fluorescence techniques at high-concentration, offer applications in both biology and chemistry, and highlight the major milestones that shatter the concentration barrier. We also hope to inspire the widespread use of these techniques so we can begin exploring the new physical phenomena lying beyond this barrier.
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Affiliation(s)
- David
S. White
- Department
of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Mackinsey A. Smith
- Department
of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Baron Chanda
- Center
for
Investigation of Membrane Excitability Diseases, Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri 63110, United States
| | - Randall H. Goldsmith
- Department
of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
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3
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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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4
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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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5
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Patra S, Claude JB, Naubron JV, Wenger J. Fast interaction dynamics of G-quadruplex and RGG-rich peptides unveiled in zero-mode waveguides. Nucleic Acids Res 2021; 49:12348-12357. [PMID: 34791437 PMCID: PMC8643622 DOI: 10.1093/nar/gkab1002] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 09/30/2021] [Accepted: 10/11/2021] [Indexed: 11/14/2022] Open
Abstract
G-quadruplexes (GQs), a non-canonical form of DNA, are receiving a huge interest as target sites for potential applications in antiviral and anticancer drug treatments. The biological functions of GQs can be controlled by specifically binding proteins known as GQs binding proteins. Some of the GQs binding proteins contain an arginine and glycine-rich sequence known as RGG peptide. Despite the important role of RGG, the GQs-RGG interaction remains poorly understood. By single molecule measurements, the interaction dynamics can be determined in principle. However, the RGG-GQs interaction occurs at micromolar concentrations, making conventional single-molecule experiments impossible with a diffraction-limited confocal microscope. Here, we use a 120 nm zero-mode waveguide (ZMW) nanoaperture to overcome the diffraction limit. The combination of dual-color fluorescence cross-correlation spectroscopy (FCCS) with FRET is used to unveil the interaction dynamics and measure the association and dissociation rates. Our data show that the RGG-GQs interaction is predominantly driven by electrostatics but that a specific affinity between the RGG sequence and the GQs structure is preserved. The single molecule approach at micromolar concentration is the key to improve our understanding of GQs function and develop its therapeutic applications by screening a large library of GQs-targeting peptides and proteins.
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Affiliation(s)
- 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
| | - Jean-Valère Naubron
- Aix Marseille Univ, CNRS, Centrale Marseille, FSCM – Spectropole, 13013 Marseille, France
| | - Jérome Wenger
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, 13013 Marseille, France
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6
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Dai B, Long Y, Wu J, Huang S, Zhao Y, Zheng L, Tao C, Guo S, Lin F, Fu Y, Zhang D, Zhuang S. Generation of flow and droplets with an ultra-long-range linear concentration gradient. LAB ON A CHIP 2021; 21:4390-4400. [PMID: 34704106 DOI: 10.1039/d1lc00749a] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In the chemical and biological fields, the creation of concentration gradient microenvironments is an important approach for many applications, such as crystal growth and drug screening. Although many concentration gradient generators have been demonstrated, current generators can hardly produce ultra-long linear concentration gradients. In this paper, we propose a concentration-gradient flow/droplet generator which consists of a microfluidic flow switch, a cavity array for stage-by-stage concentration dilution, and an optional T-junction for droplet formation. The generator can realize an ultra-long continuously-varying concentration gradient along the flow direction. Generation of a 38 mm concentration gradient was demonstrated. The length can be further extended by enlarging the capacity of the cavities and increasing the number of the stages. The concentration gradient showed high linearity in the range of 10% to 90%. Moreover, cyclic generation of a concentration gradient flow and droplets with different concentrations was realized by the generator. In a demonstration of drug screening, the generator was employed to produce paclitaxel in different concentrations. A negative correlation between the 4T1 cell viability and the paclitaxel concentration was observed after the treatment. We envision that the concentration gradient generator will be a promising candidate for various drug screening applications.
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Affiliation(s)
- Bo Dai
- Engineering Research Center of Optical Instrument and System, The Ministry of Education, Shanghai Key Laboratory of Modern Optical System, University of Shanghai for Science and Technology, Shanghai, 200093, China.
| | - Yan Long
- Engineering Research Center of Optical Instrument and System, The Ministry of Education, Shanghai Key Laboratory of Modern Optical System, University of Shanghai for Science and Technology, Shanghai, 200093, China.
| | - Jiandong Wu
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Shaoqi Huang
- Engineering Research Center of Optical Instrument and System, The Ministry of Education, Shanghai Key Laboratory of Modern Optical System, University of Shanghai for Science and Technology, Shanghai, 200093, China.
| | - Yuan Zhao
- Engineering Research Center of Optical Instrument and System, The Ministry of Education, Shanghai Key Laboratory of Modern Optical System, University of Shanghai for Science and Technology, Shanghai, 200093, China.
| | - Lulu Zheng
- Engineering Research Center of Optical Instrument and System, The Ministry of Education, Shanghai Key Laboratory of Modern Optical System, University of Shanghai for Science and Technology, Shanghai, 200093, China.
| | - Chunxian Tao
- Engineering Research Center of Optical Instrument and System, The Ministry of Education, Shanghai Key Laboratory of Modern Optical System, University of Shanghai for Science and Technology, Shanghai, 200093, China.
| | - Shiwei Guo
- Department of Hepatobiliary Pancreatic Surgery, Changhai Hospital, Naval Military Medical University, Shanghai 200433, China
| | - Francis Lin
- Department of Physics and Astronomy, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada.
| | - Yongfeng Fu
- Department of Laboratory Medicine, Shanghai Cancer Center, Fudan University, Shanghai, 200032, China.
| | - Dawei Zhang
- Engineering Research Center of Optical Instrument and System, The Ministry of Education, Shanghai Key Laboratory of Modern Optical System, University of Shanghai for Science and Technology, Shanghai, 200093, China.
| | - Songlin Zhuang
- Engineering Research Center of Optical Instrument and System, The Ministry of Education, Shanghai Key Laboratory of Modern Optical System, University of Shanghai for Science and Technology, Shanghai, 200093, China.
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7
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Winkler PM, García-Parajo MF. Correlative nanophotonic approaches to enlighten the nanoscale dynamics of living cell membranes. Biochem Soc Trans 2021; 49:2357-2369. [PMID: 34495333 PMCID: PMC8589428 DOI: 10.1042/bst20210457] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 08/03/2021] [Accepted: 08/10/2021] [Indexed: 01/31/2023]
Abstract
Dynamic compartmentalization is a prevailing principle regulating the spatiotemporal organization of the living cell membrane from the nano- up to the mesoscale. This non-arbitrary organization is intricately linked to cell function. On living cell membranes, dynamic domains or 'membrane rafts' enriched with cholesterol, sphingolipids and other certain proteins exist at the nanoscale serving as signaling and sorting platforms. Moreover, it has been postulated that other local organizers of the cell membrane such as intrinsic protein interactions, the extracellular matrix and/or the actin cytoskeleton synergize with rafts to provide spatiotemporal hierarchy to the membrane. Elucidating the intricate coupling of multiple spatial and temporal scales requires the application of correlative techniques, with a particular need for simultaneous nanometer spatial precision and microsecond temporal resolution. Here, we review novel fluorescence-based techniques that readily allow to decode nanoscale membrane dynamics with unprecedented spatiotemporal resolution and single-molecule sensitivity. We particularly focus on correlative approaches from the field of nanophotonics. Notably, we introduce a versatile planar nanoantenna platform combined with fluorescence correlation spectroscopy to study spatiotemporal heterogeneities on living cell membranes at the nano- up to the mesoscale. Finally, we outline remaining future technological challenges and comment on potential directions to advance our understanding of cell membrane dynamics under the influence of the actin cytoskeleton and extracellular matrix in uttermost detail.
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Affiliation(s)
- Pamina M. Winkler
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Barcelona, Spain
| | - María F. García-Parajo
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Barcelona, Spain
- ICREA, Pg. Lluis Companys 23, 08010 Barcelona, Spain
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8
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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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9
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Chen KY, Jamiolkowski RM, Tate AM, Fiorenza SA, Pfeil SH, Goldman YE. Fabrication of Zero Mode Waveguides for High Concentration Single Molecule Microscopy. J Vis Exp 2020:10.3791/61154. [PMID: 32478723 PMCID: PMC9020539 DOI: 10.3791/61154] [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] [Indexed: 10/31/2022] Open
Abstract
In single molecule fluorescence enzymology, background fluorescence from labeled substrates in solution often limits fluorophore concentration to pico- to nanomolar ranges, several orders of magnitude less than many physiological ligand concentrations. Optical nanostructures called zero mode waveguides (ZMWs), which are 100-200 nm in diameter apertures fabricated in a thin conducting metal such as aluminum or gold, allow imaging of individual molecules at micromolar concentrations of fluorophores by confining visible light excitation to zeptoliter effective volumes. However, the need for expensive and specialized nanofabrication equipment has precluded the widespread use of ZMWs. Typically, nanostructures such as ZMWs are obtained by direct writing using electron beam lithography, which is sequential and slow. Here, colloidal, or nanosphere, lithography is used as an alternative strategy to create nanometer-scale masks for waveguide fabrication. This report describes the approach in detail, with practical considerations for each phase. The method allows thousands of aluminum or gold ZMWs to be made in parallel, with final waveguide diameters and depths of 100-200 nm. Only common lab equipment and a thermal evaporator for metal deposition are required. By making ZMWs more accessible to the biochemical community, this method can facilitate the study of molecular processes at cellular concentrations and rates.
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Affiliation(s)
- Kevin Y Chen
- Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania
| | - Ryan M Jamiolkowski
- Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania
| | - Alyssa M Tate
- Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania
| | | | | | - Yale E Goldman
- Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania;
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10
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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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11
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Patra S, Baibakov M, Claude JB, Wenger J. Surface passivation of zero-mode waveguide nanostructures: benchmarking protocols and fluorescent labels. Sci Rep 2020; 10:5235. [PMID: 32251328 PMCID: PMC7089978 DOI: 10.1038/s41598-020-61856-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 12/19/2019] [Indexed: 11/10/2022] Open
Abstract
Zero mode waveguide (ZMW) nanoapertures efficiently confine the light down to the nanometer scale and overcome the diffraction limit in single molecule fluorescence analysis. However, unwanted adhesion of the fluorescent molecules on the ZMW surface can severely hamper the experiments. Therefore a proper surface passivation is required for ZMWs, but information is currently lacking on both the nature of the adhesion phenomenon and the optimization of the different passivation protocols. Here we monitor the influence of the fluorescent dye (Alexa Fluor 546 and 647, Atto 550 and 647N) on the non-specific adhesion of double stranded DNA molecule. We show that the nonspecific adhesion of DNA double strands onto the ZMW surface is directly mediated by the organic fluorescent dye being used, as Atto 550 and Atto 647N show a pronounced tendency to adhere to the ZMW while the Alexa Fluor 546 and 647 are remarkably free of this effect. Despite the small size of the fluorescent label, the surface charge and hydrophobicity of the dye appear to play a key role in promoting the DNA affinity for the ZMW surface. Next, different surface passivation methods (bovine serum albumin BSA, polyethylene glycol PEG, polyvinylphosphonic acid PVPA) are quantitatively benchmarked by fluorescence correlation spectroscopy to determine the most efficient approaches to prevent the adsorption of Atto 647N labeled DNA. Protocols using PVPA and PEG-silane of 1000 Da molar mass are found to drastically avoid the non-specific adsorption into ZMWs. Optimizing both the choice of the fluorescent dye and the surface passivation protocol are highly significant to expand the use of ZMWs for single molecule fluorescence applications.
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Affiliation(s)
- Satyajit Patra
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, 13013, Marseille, France
| | - Mikhail Baibakov
- 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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12
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Barulin A, Claude JB, Patra S, Bonod N, Wenger J. Deep Ultraviolet Plasmonic Enhancement of Single Protein Autofluorescence in Zero-Mode Waveguides. NANO LETTERS 2019; 19:7434-7442. [PMID: 31526002 DOI: 10.1021/acs.nanolett.9b03137] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Single molecule detection provides detailed information about molecular structures and functions but it generally requires the presence of a fluorescent marker which can interfere with the activity of the target molecule or complicate the sample production. Detecting a single protein with its natural UV autofluorescence is an attractive approach to avoid all the issues related to fluorescence labeling. However, the UV autofluorescence signal from a single protein is generally extremely weak. Here, we use aluminum plasmonics to enhance the tryptophan autofluorescence emission of single proteins in the UV range. Zero-mode waveguide nanoapertures enable the observation of the UV fluorescence of single label-free β-galactosidase proteins with increased brightness, microsecond transit times, and operation at micromolar concentrations. We demonstrate quantitative measurements of the local concentration, diffusion coefficient, and hydrodynamic radius of the label-free protein over a broad range of zero-mode waveguide diameters. Although the plasmonic fluorescence enhancement has generated a tremendous interest in the visible and near-infrared parts of the spectrum, this work pushes further the limits of plasmonic-enhanced single molecule detection into the UV range and constitutes a major step forward in our ability to interrogate single proteins in their native state at physiological concentrations.
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Affiliation(s)
- Aleksandr Barulin
- 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
| | - Nicolas Bonod
- 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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13
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Baibakov M, Patra S, Claude JB, Moreau A, Lumeau J, Wenger J. Extending Single-Molecule Förster Resonance Energy Transfer (FRET) Range beyond 10 Nanometers in Zero-Mode Waveguides. ACS NANO 2019; 13:8469-8480. [PMID: 31283186 DOI: 10.1021/acsnano.9b04378] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Single-molecule Förster resonance energy transfer (smFRET) is widely used to monitor conformations and interaction dynamics at the molecular level. However, conventional smFRET measurements are ineffective at donor-acceptor distances exceeding 10 nm, impeding the studies on biomolecules of larger size. Here, we show that zero-mode waveguide (ZMW) apertures can be used to overcome the 10 nm barrier in smFRET. Using an optimized ZMW structure, we demonstrate smFRET between standard commercial fluorophores up to 13.6 nm distance with a significantly improved FRET efficiency. To further break into the classical FRET range limit, ZMWs are combined with molecular constructs featuring multiple acceptor dyes to achieve high FRET efficiencies together with high fluorescence count rates. As we discuss general guidelines for quantitative smFRET measurements inside ZMWs, the technique can be readily applied for monitoring conformations and interactions on large molecular complexes with enhanced brightness.
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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
| | - Antonin Moreau
- Aix Marseille Univ, CNRS, Centrale Marseille , Institut Fresnel , 13013 Marseille , France
| | - Julien Lumeau
- 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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14
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Pacheco-Peña V, Navarro-Cía M. Understanding quantum emitters in plasmonic nanocavities with conformal transformation: Purcell enhancement and forces. NANOSCALE 2018; 10:13607-13616. [PMID: 29978869 DOI: 10.1039/c8nr01527a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Nanogaps supporting cavity plasmonic modes with unprecedented small mode volume are attractive platforms for tailoring the properties of light-matter interactions at the nanoscale and revealing new physics. Hitherto, there is a concerning lack of analytical solutions to divide the complex interactions into their different underlying mechanisms to gain a better understanding that can foster enhanced designs. Bowtie apertures are viewed as an effective and appealing nanocavity and are studied here within the analytical frame of conformal transformation. We show how the non-radiative Purcell enhancement of a quantum emitter within the bowtie nanocavity depends strongly not only on the geometry of the nanocavity, but also on the position and orientation of the emitter. For a 20 nm diameter (∅ 20 nm) bowtie nanocavity, we report a change of up to two orders of magnitude in the maximum non-radiative Purcell enhancement and a shift in its peak wavelength from green to infra-red. The changes are tracked down to the overlap between the emitter field and the gap plasmon mode field distribution. This analysis also enables us to understand the self-induced trapping potential of a colloidal quantum dot inside the nanocavity. Since transformations can be cascaded, the technique introduced in this work can also be applied to a wide range of nanocavities found in the literature.
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Affiliation(s)
- V Pacheco-Peña
- Emerging Technology and Materials group, School of Engineering, Newcastle University, Merz Court, Newcastle Upon Tyne NE1 7RU, UK
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15
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Crouch GM, Han D, Bohn PW. Zero-Mode Waveguide Nanophotonic Structures for Single Molecule Characterization. JOURNAL OF PHYSICS D: APPLIED PHYSICS 2018; 51:193001. [PMID: 34158676 PMCID: PMC8216246 DOI: 10.1088/1361-6463/aab8be] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Single-molecule characterization has become a crucial research tool in the chemical and life sciences, but limitations, such as limited concentration range, inability to control molecular distributions in space, and intrinsic phenomena, such as photobleaching, present significant challenges. Recent developments in non-classical optics and nanophotonics offer promising routes to mitigating these restrictions, such that even low affinity (K D ~ mM) biomolecular interactions can be studied. Here we introduce and review specific nanophotonic devices used to support single molecule studies. Optical nanostructures, such as zero-mode waveguides (ZMWs), are usually fabricated in thin gold or aluminum films and serve to confine the observation volume of optical microspectroscopy to attoliter to zeptoliter volumes. These simple nanostructures allow individual molecules to be isolated for optical and electrochemical analysis, even when the molecules of interest are present at high concentration (μM - mM) in bulk solution. Arrays of ZMWs may be combined with optical probes such as single molecule fluorescence, single molecule fluorescence resonance energy transfer (smFRET), and fluorescence correlation spectroscopy (FCS) for distributed analysis of large numbers of single-molecule reactions or binding events in parallel. Furthermore, ZMWs may be used as multifunctional devices, for example by combining optical and electrochemical functions in a single discrete architecture to achieve electrochemical ZMWs (E-ZMW). In this review, we will describe the optical properties, fabrication, and applications of ZMWs for single-molecule studies, as well as the integration of ZMWs into systems for chemical and biochemical analysis.
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Affiliation(s)
- Garrison M. Crouch
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46556
| | - Donghoon Han
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46556
| | - Paul W. Bohn
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46556
- Departmemt of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556
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16
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Taylor AB, Zijlstra P. Single-Molecule Plasmon Sensing: Current Status and Future Prospects. ACS Sens 2017; 2:1103-1122. [PMID: 28762723 PMCID: PMC5573902 DOI: 10.1021/acssensors.7b00382] [Citation(s) in RCA: 152] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 08/01/2017] [Indexed: 12/14/2022]
Abstract
Single-molecule detection has long relied on fluorescent labeling with high quantum-yield fluorophores. Plasmon-enhanced detection circumvents the need for labeling by allowing direct optical detection of weakly emitting and completely nonfluorescent species. This review focuses on recent advances in single molecule detection using plasmonic metal nanostructures as a sensing platform, particularly using a single particle-single molecule approach. In the past decade two mechanisms for plasmon-enhanced single-molecule detection have been demonstrated: (1) by plasmonically enhancing the emission of weakly fluorescent biomolecules, or (2) by monitoring shifts of the plasmon resonance induced by single-molecule interactions. We begin with a motivation regarding the importance of single molecule detection, and advantages plasmonic detection offers. We describe both detection mechanisms and discuss challenges and potential solutions. We finalize by highlighting the exciting possibilities in analytical chemistry and medical diagnostics.
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Affiliation(s)
- Adam B. Taylor
- Molecular Biosensing for
Medical Diagnostics, Faculty of Applied Physics, & Institute for
Complex Molecular Systems, Eindhoven University
of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands
| | - Peter Zijlstra
- Molecular Biosensing for
Medical Diagnostics, Faculty of Applied Physics, & Institute for
Complex Molecular Systems, Eindhoven University
of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands
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17
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18
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Ozcelik D, Parks JW, Wall TA, Stott MA, Cai H, Parks JW, Hawkins AR, Schmidt H. Optofluidic wavelength division multiplexing for single-virus detection. Proc Natl Acad Sci U S A 2015. [PMID: 26438840 DOI: 10.1073/pnas.l511921112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/23/2023] Open
Abstract
Optical waveguides simultaneously transport light at different colors, forming the basis of fiber-optic telecommunication networks that shuttle data in dozens of spectrally separated channels. Here, we reimagine this wavelength division multiplexing (WDM) paradigm in a novel context--the differentiated detection and identification of single influenza viruses on a chip. We use a single multimode interference (MMI) waveguide to create wavelength-dependent spot patterns across the entire visible spectrum and enable multiplexed single biomolecule detection on an optofluidic chip. Each target is identified by its time-dependent fluorescence signal without the need for spectral demultiplexing upon detection. We demonstrate detection of individual fluorescently labeled virus particles of three influenza A subtypes in two implementations: labeling of each virus using three different colors and two-color combinatorial labeling. By extending combinatorial multiplexing to three or more colors, MMI-based WDM provides the multiplexing power required for differentiated clinical tests and the growing field of personalized medicine.
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Affiliation(s)
- Damla Ozcelik
- Department of Electrical Engineering, University of California, Santa Cruz, CA 95064
| | - Joshua W Parks
- Department of Electrical Engineering, University of California, Santa Cruz, CA 95064
| | - Thomas A Wall
- Department of Electrical and Computer Engineering, Brigham Young University, Provo, UT 84602
| | - Matthew A Stott
- Department of Electrical and Computer Engineering, Brigham Young University, Provo, UT 84602
| | - Hong Cai
- Department of Electrical Engineering, University of California, Santa Cruz, CA 95064
| | - Joseph W Parks
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064
| | - Aaron R Hawkins
- Department of Electrical and Computer Engineering, Brigham Young University, Provo, UT 84602
| | - Holger Schmidt
- Department of Electrical Engineering, University of California, Santa Cruz, CA 95064;
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19
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Abstract
Optical waveguides simultaneously transport light at different colors, forming the basis of fiber-optic telecommunication networks that shuttle data in dozens of spectrally separated channels. Here, we reimagine this wavelength division multiplexing (WDM) paradigm in a novel context--the differentiated detection and identification of single influenza viruses on a chip. We use a single multimode interference (MMI) waveguide to create wavelength-dependent spot patterns across the entire visible spectrum and enable multiplexed single biomolecule detection on an optofluidic chip. Each target is identified by its time-dependent fluorescence signal without the need for spectral demultiplexing upon detection. We demonstrate detection of individual fluorescently labeled virus particles of three influenza A subtypes in two implementations: labeling of each virus using three different colors and two-color combinatorial labeling. By extending combinatorial multiplexing to three or more colors, MMI-based WDM provides the multiplexing power required for differentiated clinical tests and the growing field of personalized medicine.
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20
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Wang M, Zhao C, Miao X, Zhao Y, Rufo J, Liu YJ, Huang TJ, Zheng Y. Plasmofluidics: Merging Light and Fluids at the Micro-/Nanoscale. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2015; 11:4423-44. [PMID: 26140612 PMCID: PMC4856436 DOI: 10.1002/smll.201500970] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 05/07/2015] [Indexed: 05/14/2023]
Abstract
Plasmofluidics is the synergistic integration of plasmonics and micro/nanofluidics in devices and applications in order to enhance performance. There has been significant progress in the emerging field of plasmofluidics in recent years. By utilizing the capability of plasmonics to manipulate light at the nanoscale, combined with the unique optical properties of fluids and precise manipulation via micro/nanofluidics, plasmofluidic technologies enable innovations in lab-on-a-chip systems, reconfigurable photonic devices, optical sensing, imaging, and spectroscopy. In this review article, the most recent advances in plasmofluidics are examined and categorized into plasmon-enhanced functionalities in microfluidics and microfluidics-enhanced plasmonic devices. The former focuses on plasmonic manipulations of fluids, bubbles, particles, biological cells, and molecules at the micro/nanoscale. The latter includes technological advances that apply microfluidic principles to enable reconfigurable plasmonic devices and performance-enhanced plasmonic sensors. The article is concluded with perspectives on the upcoming challenges, opportunities, and possible future directions of the emerging field of plasmofluidics.
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Affiliation(s)
- Mingsong Wang
- Department of Mechanical Engineering, Materials Science and Engineering Program Texas Materials Institute The University of Texas at Austin, Austin, Texas 78712, USA
| | - Chenglong Zhao
- Department of Physics Electro-Optics, Graduate Program University of Dayton, Dayton, Ohio 45469, USA
| | - Xiaoyu Miao
- Google, Inc., 1600 Amphitheatre Pkwy, Mountain View, CA 94043, USA
| | - Yanhui Zhao
- Department of Engineering Science and Mechanics, Department of Biomedical Engineering, Materials Research Institute, Huck Institute of Life Sciences, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Joseph Rufo
- Department of Engineering Science and Mechanics, Department of Biomedical Engineering, Materials Research Institute, Huck Institute of Life Sciences, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Yan Jun Liu
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR) 3 Research Link, Singapore 117602, Singapore
| | - Tony Jun Huang
- Department of Engineering Science and Mechanics, Department of Biomedical Engineering, Materials Research Institute, Huck Institute of Life Sciences, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Yuebing Zheng
- Department of Mechanical Engineering, Materials Science and Engineering Program Texas Materials Institute The University of Texas at Austin, Austin, Texas 78712, USA
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21
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Coordinated DNA Replication by the Bacteriophage T4 Replisome. Viruses 2015; 7:3186-200. [PMID: 26102578 PMCID: PMC4488733 DOI: 10.3390/v7062766] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 06/12/2015] [Accepted: 06/16/2015] [Indexed: 11/16/2022] Open
Abstract
The T4 bacteriophage encodes eight proteins, which are sufficient to carry out coordinated leading and lagging strand DNA synthesis. These purified proteins have been used to reconstitute DNA synthesis in vitro and are a well-characterized model system. Recent work on the T4 replisome has yielded more detailed insight into the dynamics and coordination of proteins at the replication fork. Since the leading and lagging strands are synthesized in opposite directions, coordination of DNA synthesis as well as priming and unwinding is accomplished by several protein complexes. These protein complexes serve to link catalytic activities and physically tether proteins to the replication fork. Essential to both leading and lagging strand synthesis is the formation of a holoenzyme complex composed of the polymerase and a processivity clamp. The two holoenzymes form a dimer allowing the lagging strand polymerase to be retained within the replisome after completion of each Okazaki fragment. The helicase and primase also form a complex known as the primosome, which unwinds the duplex DNA while also synthesizing primers on the lagging strand. Future studies will likely focus on defining the orientations and architecture of protein complexes at the replication fork.
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22
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de Torres J, Ghenuche P, Moparthi SB, Grigoriev V, Wenger J. FRET enhancement in aluminum zero-mode waveguides. Chemphyschem 2015; 16:782-8. [PMID: 25640052 DOI: 10.1002/cphc.201402651] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 11/14/2014] [Indexed: 11/08/2022]
Abstract
Zero-mode waveguides (ZMWs) can confine light into attoliter volumes, which enables single molecule fluorescence experiments at physiological micromolar concentrations. Of the fluorescence spectroscopy techniques that can be enhanced by ZMWs, Förster resonance energy transfer (FRET) is one of the most widely used in life sciences. Combining zero-mode waveguides with FRET provides new opportunities to investigate biochemical structures or follow interaction dynamics at micromolar concentrations with single-molecule resolution. However, prior to any quantitative FRET analysis on biological samples, it is crucial to establish first the influence of the ZMW on the FRET process. Here, we quantify the FRET rates and efficiencies between individual donor-acceptor fluorophore pairs that diffuse into aluminum zero-mode waveguides. Aluminum ZMWs are important structures thanks to their commercial availability and the large amount of literature that describe their use for single-molecule fluorescence spectroscopy. We also compared the results between ZMWs milled in gold and aluminum, and found that although gold has a stronger influence on the decay rates, the lower losses of aluminum in the green spectral region provide larger fluorescence brightness enhancement factors. For both aluminum and gold ZMWs, we observed that the FRET rate scales linearly with the isolated donor decay rate and the local density of optical states. Detailed information about FRET in ZMWs unlocks their application as new devices for enhanced single-molecule FRET at physiological concentrations.
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Affiliation(s)
- Juan de Torres
- CNRS, Aix-Marseille Université, Centrale Marseille, Institut Fresnel, UMR 7249, 13013 Marseille (France)
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23
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Ghenuche P, de Torres J, Moparthi SB, Grigoriev V, Wenger J. Nanophotonic enhancement of the Förster resonance energy-transfer rate with single nanoapertures. NANO LETTERS 2014; 14:4707-4714. [PMID: 25020141 DOI: 10.1021/nl5018145] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Tailoring the light-matter interaction and the local density of optical states (LDOS) with nanophotonics provides accurate control over the luminescence properties of a single quantum emitter. This paradigm is also highly attractive to enhance the near-field Förster resonance energy transfer (FRET) between two fluorescent emitters. Despite the wide applications of FRET in nanosciences, using nanophotonics to enhance FRET has remained a debated and complex challenge. Here we demonstrate enhanced energy transfer within single donor-acceptor fluorophore pairs confined in single gold nanoapertures. Experiments monitoring both the donor and the acceptor emission photodynamics clearly establish a linear dependence of the FRET rate on the LDOS in nanoapertures, demonstrating that nanophotonics can be used to intensify the near-field energy transfer. Strikingly, we observe a significant six-fold increase in the FRET rate for large donor-acceptor separations exceeding 13 nm. Exciting opportunities are opened to investigate biochemical structures with donor-acceptor distances much beyond the classical Förster radius. Importantly, our approach is fully compatible with the detection of single biomolecules freely diffusing in water solution under physiological conditions.
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Affiliation(s)
- Petru Ghenuche
- CNRS, Aix-Marseille Université, Centrale Marseille, Institut Fresnel, UMR 7249, 13013 Marseille, France
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