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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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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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Santermans S, Hellings G, Heyns M, Van Roy W, Martens K. Unraveling the impact of nano-scaling on silicon field-effect transistors for the detection of single-molecules. NANOSCALE 2023; 15:2354-2368. [PMID: 36644797 DOI: 10.1039/d2nr05267a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Electrolyte-gated silicon field-effect transistors (FETs) capable of detecting single molecules could enable high-throughput molecular sensing chips to advance, for example, genomics or proteomics. For solid-gated silicon FETs it is well-known that nano-scaled devices become sensitive to single elementary charges near the silicon-oxide interface. However, in electrolyte-gated FETs, electrolyte screening strongly reduces sensitivity to charges near the gate oxide. The question arises whether nano-scaling electrolyte-gated FETs can entail a sufficiently large signal-to-noise ratio (SNR) for the detection of single molecules. We enhanced a technology computer-aided design tool with electrolyte screening models to calculate the impact of the FET geometry on the single-molecule signal and FET noise. Our continuum FET model shows that a sufficiently large single-molecule SNR is only obtained when nano-scaling all FET channel dimensions. Moreover, we show that the expected scaling trend of the single-molecule SNR breaks down and no longer results in improvements for geometries approaching the decananometer size. This is the characteristic size of the FET channel region modulated by a typical molecule. For gate lengths below 50 nm, the overlap of the modulated region with the highly conductive junctions leads to saturation of the SNR. For cross-sections below 10-30 nm, SNR degrades due to the overlap of the modulated region with the convex FET corners where a larger local gate capacitance reduces charge sensitivity. In our study, assuming a commercial solid-state FET noise amplitude, we find that a suspended nanowire FET architecture with 35 nm length and 5 × 10 nm2 cross-section results in the highest SNR of about 10 for a 15-base DNA oligo in a 15 mM electrolyte. In contrast with typical silicon nanowire FET sensors which possess micron-scale gate lengths, we find it to be key that all channel dimensions are scaled down to the decananometer range.
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Affiliation(s)
- Sybren Santermans
- imec, Kapeldreef 75, 3001 Leuven, Belgium.
- Department of Materials Engineering, University of Leuven, Kasteelpark Arenberg 44, 3001 Leuven, Belgium
| | | | - Marc Heyns
- imec, Kapeldreef 75, 3001 Leuven, Belgium.
- Department of Materials Engineering, University of Leuven, Kasteelpark Arenberg 44, 3001 Leuven, Belgium
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4
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Cervantes-Salguero K, Freeley M, Gwyther REA, Jones DD, Chávez JL, Palma M. Single molecule DNA origami nanoarrays with controlled protein orientation. BIOPHYSICS REVIEWS 2022; 3:031401. [PMID: 38505279 PMCID: PMC10903486 DOI: 10.1063/5.0099294] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 07/20/2022] [Indexed: 03/21/2024]
Abstract
The nanoscale organization of functional (bio)molecules on solid substrates with nanoscale spatial resolution and single-molecule control-in both position and orientation-is of great interest for the development of next-generation (bio)molecular devices and assays. Herein, we report the fabrication of nanoarrays of individual proteins (and dyes) via the selective organization of DNA origami on nanopatterned surfaces and with controlled protein orientation. Nanoapertures in metal-coated glass substrates were patterned using focused ion beam lithography; 88% of the nanoapertures allowed immobilization of functionalized DNA origami structures. Photobleaching experiments of dye-functionalized DNA nanostructures indicated that 85% of the nanoapertures contain a single origami unit, with only 3% exhibiting double occupancy. Using a reprogrammed genetic code to engineer into a protein new chemistry to allow residue-specific linkage to an addressable ssDNA unit, we assembled orientation-controlled proteins functionalized to DNA origami structures; these were then organized in the arrays and exhibited single molecule traces. This strategy is of general applicability for the investigation of biomolecular events with single-molecule resolution in defined nanoarrays configurations and with orientational control of the (bio)molecule of interest.
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Affiliation(s)
- K. Cervantes-Salguero
- Department of Chemistry, School of Physical and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - M. Freeley
- Department of Chemistry, School of Physical and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - R. E. A. Gwyther
- Division of Molecular Biosciences, School of Biosciences, Main Building, Cardiff University, Cardiff, Wales, United Kingdom
| | - D. D. Jones
- Division of Molecular Biosciences, School of Biosciences, Main Building, Cardiff University, Cardiff, Wales, United Kingdom
| | - J. L. Chávez
- Air Force Research Laboratory, 711th Human Performance Wing, Wright Patterson Air Force Base, Dayton, Ohio 45433-7901, USA
| | - M. Palma
- Department of Chemistry, School of Physical and Chemical Sciences, Queen Mary University of London, London, United Kingdom
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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 (BASEL, SWITZERLAND) 2022; 12:1755. [PMID: 35630978 PMCID: PMC9147361 DOI: 10.3390/nano12101755] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [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
| | - 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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Masud AA, Arefin SMN, Fairooz F, Fu X, Moonschi F, Srijanto BR, Neupane KR, Aryal S, Calabro R, Kim DY, Collier CP, Chowdhury MH, Richards CI. Photoluminescence Enhancement, Blinking Suppression, and Improved Biexciton Quantum Yield of Single Quantum Dots in Zero Mode Waveguides. J Phys Chem Lett 2021; 12:3303-3311. [PMID: 33765768 DOI: 10.1021/acs.jpclett.1c00450] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The capability of quantum dots to generate both single and multiexcitons can be harnessed for a wide variety of applications, including those that require high optical gain. Here, we use time-correlated photoluminescence (PL) spectroscopy to demonstrate that the isolation of single CdSeTe/ZnS core-shell, nanocrystal quantum dots (QDs) in Zero Mode Waveguides (ZMWs) leads to a significant modification in PL intensity, blinking dynamics, and biexciton behavior. QDs in aluminum ZMWs (AlZMWs) exhibited a 15-fold increase in biexciton emission, indicating a preferential enhancement of the biexciton radiative decay rate as compared to the single exciton rate. The increase in biexciton behavior was accompanied by a decrease in blinking events due to a shortening in the dark state residence time. These results indicate that plasmon mediated enhanced decay rates of QDs in AlZMWs lead to substantial changes in the photophysical properties of single quantum dots, including an increase in biexciton behavior.
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Affiliation(s)
- Abdullah Al Masud
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - S M Nayeem Arefin
- Department of Electrical and Electronic Engineering, Independent University, Bangladesh (IUB), Dhaka, Bangladesh
| | - Fatema Fairooz
- Department of Electrical and Electronic Engineering, Independent University, Bangladesh (IUB), Dhaka, Bangladesh
| | - Xu Fu
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Faruk Moonschi
- Department of Physiology, University of Kentucky, Lexington, Kentucky 40536, United States
| | - Bernadeta R Srijanto
- Center for Nanophase Materials Sciences, Oakridge National Lab, Oakridge, Tennessee 37831, United States
| | - Khaga Raj Neupane
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Surya Aryal
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Rosemary Calabro
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Doo-Young Kim
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
| | - C Patrick Collier
- Center for Nanophase Materials Sciences, Oakridge National Lab, Oakridge, Tennessee 37831, United States
| | - Mustafa Habib Chowdhury
- Department of Electrical and Electronic Engineering, Independent University, Bangladesh (IUB), Dhaka, Bangladesh
| | - Christopher I Richards
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506, United States
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7
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Miclotte G, Martens K, Fostier J. Computational assessment of the feasibility of protonation-based protein sequencing. PLoS One 2020; 15:e0238625. [PMID: 32915813 PMCID: PMC7485799 DOI: 10.1371/journal.pone.0238625] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 08/20/2020] [Indexed: 02/05/2023] Open
Abstract
Recent advances in DNA sequencing methods revolutionized biology by providing highly accurate reads, with high throughput or high read length. These read data are being used in many biological and medical applications. Modern DNA sequencing methods have no equivalent in protein sequencing, severely limiting the widespread application of protein data. Recently, several optical protein sequencing methods have been proposed that rely on the fluorescent labeling of amino acids. Here, we introduce the reprotonation-deprotonation protein sequencing method. Unlike other methods, this proposed technique relies on the measurement of an electrical signal and requires no fluorescent labeling. In reprotonation-deprotonation protein sequencing, the terminal amino acid is identified through its unique protonation signal, and by repeatedly cleaving the terminal amino acids one-by-one, each amino acid in the peptide is measured. By means of simulations, we show that, given a reference database of known proteins, reprotonation-deprotonation sequencing has the potential to correctly identify proteins in a sample. Our simulations provide target values for the signal-to-noise ratios that sensor devices need to attain in order to detect reprotonation-deprotonation events, as well as suitable pH values and required measurement times per amino acid. For instance, an SNR of 10 is required for a 61.71% proteome recovery rate with 100 ms measurement time per amino acid.
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Affiliation(s)
| | | | - Jan Fostier
- IDLab, Ghent University-Imec, Ghent, Belgium
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8
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Al Masud A, Martin WE, Moonschi FH, Park SM, Srijanto BR, Graham KR, Collier CP, Richards CI. Mixed metal zero-mode guides (ZMWs) for tunable fluorescence enhancement. NANOSCALE ADVANCES 2020; 2:1894-1903. [PMID: 36132495 PMCID: PMC9419232 DOI: 10.1039/c9na00641a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 03/25/2020] [Indexed: 05/28/2023]
Abstract
Zero-mode waveguides (ZMWs) are capable of modifying fluorescence emission through interactions with surface plasmon modes leading to either plasmon-enhanced fluorescence or quenching. Enhancement requires spectral overlap of the plasmon modes with the absorption or emission of the fluorophore. Thus, enhancement is limited to fluorophores in resonance with metals (e.g. Al, Au, Ag) used for ZMWs. The ability to tune interactions to match a wider range of fluorophores across the visible spectra would significantly extend the utility of ZMWs. We fabricated ZMWs composed of aluminum and gold individually and also in mixtures of three different ratios, (Al : Au; 75 : 25, 50 : 50, 25 : 75). We characterized the effect of mixed-metal ZMWs on single-molecule emission for a range fluorophores across the visible spectrum. Mixed metal ZMWs exhibited a shift in the spectral range where they exhibited the maximum fluorescence enhancement allowing us to match the emission of fluorophores that were nonresonant with single metal ZMWs. We also compared the effect of mixed-metal ZMWs on the photophysical properties of fluorescent molecules due to metal-molecule interactions. We quantified changes in fluorescence lifetimes and photostability that were dependent on the ratio of Au and Al. Tuning the enhancement properties of ZMWs by changing the ratio of Au and Al allowed us to match the fluorescence of fluorophores that emit in different regions of the visible spectrum.
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Affiliation(s)
- Abdullah Al Masud
- Department of Chemistry, University of Kentucky Lexington KY 40506 USA
| | - W Elliott Martin
- Department of Chemistry, University of Kentucky Lexington KY 40506 USA
| | - Faruk H Moonschi
- Department of Physiology, School of Medicine, University of Kentucky KY 40506 USA
| | - So Min Park
- Department of Chemical and Materials Engineering, Univ. of Kentucky 40506 USA
| | - Bernadeta R Srijanto
- Center for Nanophase Materials Sciences, Oakridge National Lab Oakridge TN 37831 USA
| | - Kenneth R Graham
- Department of Chemistry, University of Kentucky Lexington KY 40506 USA
| | - C Patrick Collier
- Center for Nanophase Materials Sciences, Oakridge National Lab Oakridge TN 37831 USA
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9
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Wu C, Maley AM, Walt DR. Single-molecule measurements in microwells for clinical applications. Crit Rev Clin Lab Sci 2019:1-21. [PMID: 31865834 DOI: 10.1080/10408363.2019.1700903] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The ability to detect and analyze proteins, nucleic acids, and other biomolecules is critical for clinical diagnostics and for understanding the underlying mechanisms of disease. Current detection methods in clinical and research laboratories rely upon bulk measurement techniques such as immunoassays, polymerase chain reaction, and mass spectrometry to detect these biomarkers. However, many potentially useful protein or nucleic acid biomarkers in blood, saliva, or other biofluids exist at concentrations well below the detection limits of current methods, necessitating the development of more sensitive technologies. Single-molecule measurements are poised to address this challenge, vastly improving sensitivity for detecting low abundance biomarkers and rare events within a population. Microwell arrays have emerged as a powerful tool for single-molecule measurements, enabling ultrasensitive detection of disease-relevant biomolecules in easily accessible biofluids. This review discusses the development, fundamentals, and clinical applications of microwell-based single-molecule methods, as well as challenges and future directions for translating these methods to the clinic.
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Affiliation(s)
- Connie Wu
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.,Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA
| | - Adam M Maley
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.,Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA
| | - David R Walt
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.,Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA
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10
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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: 17] [Impact Index Per Article: 2.8] [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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