51
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Fu F, Li L, Luo Q, Li Q, Guo T, Yu M, Song Y, Song E. Selective and sensitive detection of lysozyme based on plasmon resonance light-scattering of hydrolyzed peptidoglycan stabilized-gold nanoparticles. Analyst 2019; 143:1133-1140. [PMID: 29392248 DOI: 10.1039/c7an01570d] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The simple, economic, rapid, and sensitive detection of lysozyme has an important significance for disease diagnosis since it is a potential biomarker. In this work, a new detection strategy for lysozyme was developed based on the change of the plasmon resonance light scattering (PRLS) signal of peptidoglycan stabilized gold nanoparticles (PGN-AuNPs). Peptidoglycan (PGN) was employed as a stabilizer to prepare PGN-AuNPs which have the properties of a uniform particle size, good stability, and a specific biological function. Due to the specific cleavage of lysozyme to PGN, a very simple specific and sensitive detection method for lysozyme was developed based on the PRLS signal of PGN-AuNPs after mixing with lysozyme for 1.5 h. The enhanced PRLS signals (ΔIPRLS, at 560 nm) increased linearly with increasing lysozyme in the range 5 nM to 1600 nM with the detection limit down to 2.32 nM (ΔIPRLS = 41.6397 + 0.5332c, R = 0.9961). When the PGN-AuNP based method was applied to assay lysozyme in authentic human serum samples, the recovery efficiency was 106.76-119.32% with the relative standard deviations in the range of 0.14-3.11%, showing good feasibility. The PGN-AuNP based method for lysozyme assay developed here is simple, rapid, selective, and sensitive, which is expected to provide a feasible new method for the diagnosis or prognosis of lysozyme-related diseases in a clinical setting.
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Affiliation(s)
- Fei Fu
- Key Laboratory of Luminescence and Real-Time Analytical Chemistry, Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing, 400715, China.
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52
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Hong T, Wang T, Xu YQ. Direct Measurement of π Coupling at the Single-Molecule Level using a Carbon Nanotube Force Sensor. NANO LETTERS 2018; 18:7883-7888. [PMID: 30457874 DOI: 10.1021/acs.nanolett.8b03690] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We report a carbon nanotube (CNT) force sensor that combines a suspended CNT transistor with dual-trap optical tweezers to explore the interactions between two individual molecules in the near-equilibrium regime with sub-piconewton resolution. The directly measured equilibrium force (1.2 ± 0.5 pN) is likely related to the binding force between a CNT and a single DNA base, where two aromatic rings spontaneously attract to each other due to the noncovalent forces between them. On the basis of our force measurements, the binding free energy per base is calculated (∼0.34 eV), which is in good agreement with theoretical simulations. Moreover, three-dimensional scanning photocurrent microscopy enables us to simultaneously monitor the morphology changes of the CNT, leading to a comprehensive reconstruction of the CNT-DNA binding dynamics. These experimental results shed light on the fundamental understanding of the mechanical coupling between CNTs and DNA molecules and, more importantly, provide a new platform for direct observation of intermolecular interfaces at the single-molecule level.
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53
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Xu Y, Gao Y, Su Y, Sun L, Xing F, Fan C, Li D. Single-Molecule Studies of Allosteric Inhibition of Individual Enzyme on a DNA Origami Reactor. J Phys Chem Lett 2018; 9:6786-6794. [PMID: 30412409 DOI: 10.1021/acs.jpclett.8b02992] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Unraveling the conformational changes of enzymes together with inhibition kinetics during an enzymatic reaction has great potential in screening therapeutic candidates; however, it remains challenging due to the transient nature of each intermediate step. We report our study on the noncompetitive inhibition of horseradish peroxidase with single-turnover resolution using single-molecule fluorescence microscopy. By introducing DNA origami as an addressable nanoreactor, we observe the coexistence of nascent-formed fluorescent product on both catalytic and docking sites. We further propose a single-molecule kinetic model to reveal the interplay between product generation and noncompetitive inhibition and find three distinct inhibitor releasing pathways. Moreover, the kinetic isotope effect experiment indicates a strong correlation between catalytic and docking sites, suggesting an allosteric conformational change in noncompetitive inhibition. A memory effect is also observed. This work provides an in-depth understanding of the correlation between enzyme behavior and enzymatic conformational fluctuation, substrate conversion, and product releasing pathway and kinetics.
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Affiliation(s)
- Yan Xu
- School of Chemistry and Molecular Engineering , East China Normal University , Shanghai 200241 , China
- Division of Physical Biology & Bioimaging Center, Shanghai Synchrotron Radiation Facility, Key Laboratory of Interfacial Physics and Technology , Shanghai Institute of Applied Physics, Chinese Academy of Sciences , Shanghai 201800 , China
- National Engineering Research Center for Nanotechnology , Shanghai 200241 , China
| | - Yanjing Gao
- Division of Physical Biology & Bioimaging Center, Shanghai Synchrotron Radiation Facility, Key Laboratory of Interfacial Physics and Technology , Shanghai Institute of Applied Physics, Chinese Academy of Sciences , Shanghai 201800 , China
- University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Yingying Su
- School of Chemistry and Molecular Engineering , East China Normal University , Shanghai 200241 , China
- Department of Chemistry, College of Science , Shanghai University , Shanghai 200444 , China
| | - Lele Sun
- Division of Physical Biology & Bioimaging Center, Shanghai Synchrotron Radiation Facility, Key Laboratory of Interfacial Physics and Technology , Shanghai Institute of Applied Physics, Chinese Academy of Sciences , Shanghai 201800 , China
- University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Feifei Xing
- Department of Chemistry, College of Science , Shanghai University , Shanghai 200444 , China
| | - Chunhai Fan
- Division of Physical Biology & Bioimaging Center, Shanghai Synchrotron Radiation Facility, Key Laboratory of Interfacial Physics and Technology , Shanghai Institute of Applied Physics, Chinese Academy of Sciences , Shanghai 201800 , China
| | - Di Li
- School of Chemistry and Molecular Engineering , East China Normal University , Shanghai 200241 , China
- Division of Physical Biology & Bioimaging Center, Shanghai Synchrotron Radiation Facility, Key Laboratory of Interfacial Physics and Technology , Shanghai Institute of Applied Physics, Chinese Academy of Sciences , Shanghai 201800 , China
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54
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Neves MMPDS, Martín-Yerga D. Advanced Nanoscale Approaches to Single-(Bio)entity Sensing and Imaging. BIOSENSORS 2018; 8:E100. [PMID: 30373209 PMCID: PMC6316691 DOI: 10.3390/bios8040100] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Revised: 10/11/2018] [Accepted: 10/23/2018] [Indexed: 01/01/2023]
Abstract
Individual (bio)chemical entities could show a very heterogeneous behaviour under the same conditions that could be relevant in many biological processes of significance in the life sciences. Conventional detection approaches are only able to detect the average response of an ensemble of entities and assume that all entities are identical. From this perspective, important information about the heterogeneities or rare (stochastic) events happening in individual entities would remain unseen. Some nanoscale tools present interesting physicochemical properties that enable the possibility to detect systems at the single-entity level, acquiring richer information than conventional methods. In this review, we introduce the foundations and the latest advances of several nanoscale approaches to sensing and imaging individual (bio)entities using nanoprobes, nanopores, nanoimpacts, nanoplasmonics and nanomachines. Several (bio)entities such as cells, proteins, nucleic acids, vesicles and viruses are specifically considered. These nanoscale approaches provide a wide and complete toolbox for the study of many biological systems at the single-entity level.
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Affiliation(s)
| | - Daniel Martín-Yerga
- Department of Chemical Engineering, KTH Royal Institute of Technology, 100-44 Stockholm, Sweden.
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55
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Lee Y, Trocchia SM, Warren SB, Young EF, Vernick S, Shepard KL. Electrically Controllable Single-Point Covalent Functionalization of Spin-Cast Carbon-Nanotube Field-Effect Transistor Arrays. ACS NANO 2018; 12:9922-9930. [PMID: 30260623 PMCID: PMC6887518 DOI: 10.1021/acsnano.8b03073] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Single-point-functionalized carbon-nanotube field-effect transistors (CNTFETs) have been used to sense conformational changes and binding events in protein and nucleic acid structures from intrinsic molecular charge. The key to utilizing these devices as single-molecule sensors is the ability to attach a single probe molecule to an individual device. In contrast, with noncovalent attachment approaches such as those based on van der Waals interactions, covalent attachment approaches generally deliver higher stability but have traditionally been more difficult to control, resulting in low yield. Here, we present a single-point-functionalization method for CNTFET arrays based on electrochemical control of a diazonium reaction to create sp3 defects, combined with a scalable spin-casting method for fabricating large arrays of devices on arbitrary substrates. Attachment of probe DNA to the functionalized device enables single-molecule detection of DNA hybridization with complementary target, verifying the single-point functionalization. Overall, this method enables single-point defect generation with 80% yield.
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Affiliation(s)
- Yoonhee Lee
- Department of Electrical Engineering, Columbia University, New York, NY 10027, USA
| | - Scott M. Trocchia
- Department of Electrical Engineering, Columbia University, New York, NY 10027, USA
| | | | - Erik F. Young
- Department of Electrical Engineering, Columbia University, New York, NY 10027, USA
| | - Sefi Vernick
- Agricultural Research Organization, Volcani Center, Institute of Agricultural Engineering, Bet Dagan, Israel
| | - Kenneth L. Shepard
- Department of Electrical Engineering, Columbia University, New York, NY 10027, USA
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56
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Ono T, Ichiki T, Noji H. Digital enzyme assay using attoliter droplet array. Analyst 2018; 143:4923-4929. [PMID: 30221644 PMCID: PMC6180314 DOI: 10.1039/c8an01152d] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 08/18/2018] [Indexed: 01/12/2023]
Abstract
Single-molecule digital enzyme assay using micron-sized droplet array is a promising analysis method to quantify biomolecules at extremely low concentrations. However, multiplex digital enzyme assays are still difficult to access because the best buffer conditions can vary largely among enzymes. In addition, the best conditions for flurogenic compounds to retain high quantum efficiency and to avoid leakage into the oil phase can be also very different. In this study, digital enzyme assay was performed using an array of nanometer-sized droplets of 200 aL volume, termed 'nanocell'. Due to the small reaction volume, nanocell enhanced the accumulation rate of fluorescent products by a factor of 100 when compared with micron-sized reactors. Nanocell also enabled oil-free sealing of reactors: when flushed with an air flow, nanocell displayed water droplets under air, allowing enzymes to catalyze the reaction at the same rate as in oil-sealed reactors. Dual digital enzyme assay was also demonstrated using β-galactosidase and alkaline phosphatase (ALP) at pH 7.4, which is far from the optimum condition for ALP. Even under such a non-optimum condition, ALP molecules were successfully detected. Nanocell could largely expand the applicability of digital bioassay for enzymes under non-optimum conditions or enzymes of low turnover rate. The sealing of the reactor with air would also expand the applicability, allowing the use of fluorescent dyes that leak into oil.
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Affiliation(s)
- Takao Ono
- Department of Applied Chemistry
, Graduate School of Engineering
, The University of Tokyo
,
Japan
.
| | - Takanori Ichiki
- Department of Materials Engineering
, Graduate School of Engineering
, The University of Tokyo
,
Japan
| | - Hiroyuki Noji
- Department of Applied Chemistry
, Graduate School of Engineering
, The University of Tokyo
,
Japan
.
- ImPACT Program
, Japan Science and Technology Agency
,
Saitama 332-0012
, Japan
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57
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Froberg J, Choi WS, Sedigh A, Anajafi T, Farmakes J, Yang Z, Mallik S, Srivastava DK, Choi Y. Real-time tracking of single-molecule collagenase on native collagen and partially structured collagen-mimic substrates. Chem Commun (Camb) 2018; 54:10248-10251. [PMID: 30091759 PMCID: PMC6145137 DOI: 10.1039/c8cc04601h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/01/2024]
Abstract
The dynamic interactions of an individual matrix metalloproteinase-1 were imaged and monitored in the presence of either triple-helical or non-triple-helical, partially structured collagen-mimic substrates. The enzyme exhibited ten-fold increased catalytic turnover rates with the structurally modified substrate by skipping the triple-helix unwinding step during the catalytic pathway.
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Affiliation(s)
- James Froberg
- Department of Physics, North Dakota State University, Fargo, North Dakota, 58108, United States,
| | - Woo-Sik Choi
- Department of Physics, North Dakota State University, Fargo, North Dakota, 58108, United States,
| | - Abbas Sedigh
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58108, United States
| | - Tayebeh Anajafi
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo, North Dakota 58108, United States
| | - Jasmin Farmakes
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58108, United States
| | - Zhongyu Yang
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58108, United States
| | - Sanku Mallik
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo, North Dakota 58108, United States
| | - D. K. Srivastava
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58108, United States
| | - Yongki Choi
- Department of Physics, North Dakota State University, Fargo, North Dakota, 58108, United States,
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58
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You S, Froberg J, Yu J, Haldar M, Sedigh A, Mallik S, Srivastava DK, Choi Y. Real-time monitoring of conformational transitions of single-molecule histone deacetylase 8 with nanocircuits. Chem Commun (Camb) 2018; 53:3307-3310. [PMID: 28261707 DOI: 10.1039/c6cc09949a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Using single-molecule approaches, we directly observed the dynamic interaction between HDAC8 and various ligands as well as conformational interconversions during the catalytic reaction. Statistical analysis identified key kinetic parameters, demonstrating that the enzymatic activity is highly sensitive to both minor variations in the ligand structures and small synthetic molecules.
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Affiliation(s)
- Seungyong You
- Department of Physics, North Dakota State University, Fargo, North Dakota 58108, USA.
| | - James Froberg
- Department of Physics, North Dakota State University, Fargo, North Dakota 58108, USA.
| | - Junru Yu
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58108, USA
| | - Manas Haldar
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo, North Dakota 58108, USA
| | - Abbas Sedigh
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58108, USA
| | - Sanku Mallik
- Department of Pharmaceutical Sciences, North Dakota State University, Fargo, North Dakota 58108, USA
| | - D K Srivastava
- Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58108, USA
| | - Yongki Choi
- Department of Physics, North Dakota State University, Fargo, North Dakota 58108, USA.
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59
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Xu X, Clément P, Eklöf-Österberg J, Kelley-Loughnane N, Moth-Poulsen K, Chávez JL, Palma M. Reconfigurable Carbon Nanotube Multiplexed Sensing Devices. NANO LETTERS 2018; 18:4130-4135. [PMID: 29923734 DOI: 10.1021/acs.nanolett.8b00856] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Here we report on the fabrication of reconfigurable and solution processable nanoscale biosensors with multisensing capability, based on single-walled carbon nanotubes (SWCNTs). Distinct DNA-wrapped (hence water-soluble) CNTs were immobilized from solution onto different prepatterned electrodes on the same chip, via a low-cost dielectrophoresis (DEP) methodology. The CNTs were functionalized with specific, and different, aptamer sequences that were employed as selective recognition elements for biomarkers indicative of stress and neuro-trauma conditions. Multiplexed detection of three different biomarkers was successfully performed, and real-time detection was achieved in serum down to physiologically relevant concentrations of 50 nM, 10 nM, and 500 pM for cortisol, dehydroepiandrosterone-sulfate (DHEAS), and neuropeptide Y (NPY), respectively. Additionally, the fabricated nanoscale devices were shown to be reconfigurable and reusable via a simple cleaning procedure. The general applicability of the strategy presented, and the facile device fabrication from aqueous solution, hold great potential for the development of the next generation of low power consumption portable diagnostic assays for the simultaneous monitoring of different health parameters.
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Affiliation(s)
- Xinzhao Xu
- School of Biological and Chemical Sciences, Institute of Bioengineering, and Materials Research Institute , Queen Mary University of London , Mile End Road , London , E1 4NS , United Kingdom
| | - Pierrick Clément
- School of Biological and Chemical Sciences, Institute of Bioengineering, and Materials Research Institute , Queen Mary University of London , Mile End Road , London , E1 4NS , United Kingdom
| | - Johnas Eklöf-Österberg
- Department of Chemistry and Chemical Engineering , Chalmers University of Technology , Gothenburg , 412 96 , Sweden
| | - Nancy Kelley-Loughnane
- Air Force Research Laboratory, 711th Human Performance Wing , Wright-Patterson Air Force Base , Dayton , Ohio 45433 , United States
| | - Kasper Moth-Poulsen
- Department of Chemistry and Chemical Engineering , Chalmers University of Technology , Gothenburg , 412 96 , Sweden
| | - Jorge L Chávez
- Air Force Research Laboratory, 711th Human Performance Wing , Wright-Patterson Air Force Base , Dayton , Ohio 45433 , United States
| | - Matteo Palma
- School of Biological and Chemical Sciences, Institute of Bioengineering, and Materials Research Institute , Queen Mary University of London , Mile End Road , London , E1 4NS , United Kingdom
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60
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Wang ZZ, Zhan LQ, Chen XX. Two types of lysozymes from the whitefly Bemisia tabaci: Molecular characterization and functional diversification. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2018; 81:252-261. [PMID: 29247722 DOI: 10.1016/j.dci.2017.12.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 12/12/2017] [Accepted: 12/12/2017] [Indexed: 06/07/2023]
Abstract
Lysozyme is well-known as an immune effector in the immune system. Here we identified three genes including one c-type lysozyme, Btlysc, and two i-type lysozymes, Btlysi1 and Btlysi2, from the whitefly Bemisia tabaci. All three lysozymes were constitutively expressed in different tissues and developmental stages, but the two types of lysozymes showed different expression patterns. The expression levels of Btlysi1 and Btlysi2 were dramatically induced after the whitefly fed with different host plants while the expression level of Btlysc kept unchanged. After fungal infection and begomovirus acquisition, Btlysc expression was significantly upregulated while Btlysi1 and Btlysi2 expression were basically not induced. Furthermore, we found that Btlysc showed muramidase and antibacterial activities. Altogether, our results suggest that the two types of lysozymes act in two different ways in B. tabaci, that is, Btlysc is involved in the whitefly immune system while Btlysi1 and Btlysi2 may play a role in digestion or nutrition absorption.
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Affiliation(s)
- Zhi-Zhi Wang
- State Key Lab of Rice Biology and Ministry of Agriculture Key Lab of Molecular Biology of Crop Pathogens and Insect Pests, Institute of Insect Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China
| | - Le-Qing Zhan
- State Key Lab of Rice Biology and Ministry of Agriculture Key Lab of Molecular Biology of Crop Pathogens and Insect Pests, Institute of Insect Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China
| | - Xue-Xin Chen
- State Key Lab of Rice Biology and Ministry of Agriculture Key Lab of Molecular Biology of Crop Pathogens and Insect Pests, Institute of Insect Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China.
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61
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Direct observation of single-molecule hydrogen-bond dynamics with single-bond resolution. Nat Commun 2018; 9:807. [PMID: 29476061 PMCID: PMC5825177 DOI: 10.1038/s41467-018-03203-1] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 01/26/2018] [Indexed: 12/18/2022] Open
Abstract
The hydrogen bond represents a fundamental interaction widely existing in nature, which plays a key role in chemical, physical and biochemical processes. However, hydrogen bond dynamics at the molecular level are extremely difficult to directly investigate. Here, in this work we address direct electrical measurements of hydrogen bond dynamics at the single-molecule and single-event level on the basis of the platform of molecular nanocircuits, where a quadrupolar hydrogen bonding system is covalently incorporated into graphene point contacts to build stable supramolecule-assembled single-molecule junctions. The dynamics of individual hydrogen bonds in different solvents at different temperatures are studied in combination with density functional theory. Both experimental and theoretical results consistently show a multimodal distribution, stemming from the stochastic rearrangement of the hydrogen bond structure mainly through intermolecular proton transfer and lactam-lactim tautomerism. This work demonstrates an approach of probing hydrogen bond dynamics with single-bond resolution, making an important contribution to broad fields beyond supramolecular chemistry.
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62
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Duan BK, Cavanagh PE, Li X, Walt DR. Ultrasensitive Single-Molecule Enzyme Detection and Analysis Using a Polymer Microarray. Anal Chem 2018; 90:3091-3098. [PMID: 29425025 DOI: 10.1021/acs.analchem.7b03980] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
This report describes a novel method for isolating and detecting individual enzyme molecules using polymer arrays of picoliter microwells. A fluidic flow-cell device containing an array of microwells is fabricated in cyclic olefin polymer (COP). The use of COP microwell arrays simplifies experiments by eliminating extensive device preparation and surface functionalization that are common in other microwell array formats. Using a simple and robust loading method to introduce the reaction solution, individual enzyme molecules are trapped in picoliter microwells and subsequently isolated and sealed by fluorinated oil. The sealing is stable for hours in the COP device. The picoliter microwell device can measure enzyme concentrations in the low-femtomolar range by counting the number of active wells using a digital read-out. These picoliter microwell arrays can also easily be regenerated and reused.
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Affiliation(s)
- Barrett K Duan
- Department of Pathology , Harvard Medical School , Brigham and Women's Hospital, Wyss Institute for Biologically Inspired Engineering, Building for Transformative Medicine, 60 Fenwood Road , Boston , Massachusetts 02115 , United States
| | - Peter E Cavanagh
- Department of Pathology , Harvard Medical School , Brigham and Women's Hospital, Wyss Institute for Biologically Inspired Engineering, Building for Transformative Medicine, 60 Fenwood Road , Boston , Massachusetts 02115 , United States
| | - Xiang Li
- Department of Pathology , Harvard Medical School , Brigham and Women's Hospital, Wyss Institute for Biologically Inspired Engineering, Building for Transformative Medicine, 60 Fenwood Road , Boston , Massachusetts 02115 , United States
| | - David R Walt
- Department of Pathology , Harvard Medical School , Brigham and Women's Hospital, Wyss Institute for Biologically Inspired Engineering, Building for Transformative Medicine, 60 Fenwood Road , Boston , Massachusetts 02115 , United States
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63
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Ptaszyński K. First-passage times in renewal and nonrenewal systems. Phys Rev E 2018; 97:012127. [PMID: 29448475 DOI: 10.1103/physreve.97.012127] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Indexed: 11/07/2022]
Abstract
Fluctuations in stochastic systems are usually characterized by full counting statistics, which analyzes the distribution of the number of events taking place in the fixed time interval. In an alternative approach, the distribution of the first-passage times, i.e., the time delays after which the counting variable reaches a certain threshold value, is studied. This paper presents the approach to calculate the first-passage time distribution in systems in which the analyzed current is associated with an arbitrary set of transitions within the Markovian network. Using this approach, it is shown that when the subsequent first-passage times are uncorrelated, there exist strict relations between the cumulants of the full counting statistics and the first-passage time distribution. On the other hand, when the correlations of the first-passage times are present, their distribution may provide additional information about the internal dynamics of the system in comparison to the full counting statistics; for example, it may reveal the switching between different dynamical states of the system. Additionally, I show that breaking of the fluctuation theorem for first-passage times may reveal the multicyclic nature of the Markovian network.
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Affiliation(s)
- Krzysztof Ptaszyński
- Institute of Molecular Physics, Polish Academy of Sciences, ul. M. Smoluchowskiego 17, 60-179 Poznań, Poland
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64
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Guan J, Jia C, Li Y, Liu Z, Wang J, Yang Z, Gu C, Su D, Houk KN, Zhang D, Guo X. Direct single-molecule dynamic detection of chemical reactions. SCIENCE ADVANCES 2018; 4:eaar2177. [PMID: 29487914 PMCID: PMC5817934 DOI: 10.1126/sciadv.aar2177] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Accepted: 01/16/2018] [Indexed: 05/03/2023]
Abstract
Single-molecule detection can reveal time trajectories and reaction pathways of individual intermediates/transition states in chemical reactions and biological processes, which is of fundamental importance to elucidate their intrinsic mechanisms. We present a reliable, label-free single-molecule approach that allows us to directly explore the dynamic process of basic chemical reactions at the single-event level by using stable graphene-molecule single-molecule junctions. These junctions are constructed by covalently connecting a single molecule with a 9-fluorenone center to nanogapped graphene electrodes. For the first time, real-time single-molecule electrical measurements unambiguously show reproducible large-amplitude two-level fluctuations that are highly dependent on solvent environments in a nucleophilic addition reaction of hydroxylamine to a carbonyl group. Both theoretical simulations and ensemble experiments prove that this observation originates from the reversible transition between the reactant and a new intermediate state within a time scale of a few microseconds. These investigations open up a new route that is able to be immediately applied to probe fast single-molecule physics or biophysics with high time resolution, making an important contribution to broad fields beyond reaction chemistry.
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Affiliation(s)
- Jianxin Guan
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
| | - Chuancheng Jia
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
- Beijing National Laboratory for Molecular Sciences, Chinese Academy of Sciences Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
| | - Yanwei Li
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
- Environment Research Institute, Shandong University, Jinan 250100, P. R. China
| | - Zitong Liu
- Beijing National Laboratory for Molecular Sciences, Chinese Academy of Sciences Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
| | - Jinying Wang
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
| | - Zhongyue Yang
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Chunhui Gu
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
| | - Dingkai Su
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
| | - Kendall N. Houk
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Deqing Zhang
- Beijing National Laboratory for Molecular Sciences, Chinese Academy of Sciences Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
| | - Xuefeng Guo
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
- Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, P. R. China
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65
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Slow domain reconfiguration causes power-law kinetics in a two-state enzyme. Proc Natl Acad Sci U S A 2018; 115:513-518. [PMID: 29298911 DOI: 10.1073/pnas.1714401115] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Protein dynamics are typically captured well by rate equations that predict exponential decays for two-state reactions. Here, we describe a remarkable exception. The electron-transfer enzyme quiescin sulfhydryl oxidase (QSOX), a natural fusion of two functionally distinct domains, switches between open- and closed-domain arrangements with apparent power-law kinetics. Using single-molecule FRET experiments on time scales from nanoseconds to milliseconds, we show that the unusual open-close kinetics results from slow sampling of an ensemble of disordered domain orientations. While substrate accelerates the kinetics, thus suggesting a substrate-induced switch to an alternative free energy landscape of the enzyme, the power-law behavior is also preserved upon electron load. Our results show that the slow sampling of open conformers is caused by a variety of interdomain interactions that imply a rugged free energy landscape, thus providing a generic mechanism for dynamic disorder in multidomain enzymes.
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66
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Zaki AJ, Hartley A, Reddington SC, Thomas SK, Watson P, Hayes A, Moskalenko AV, Craciun MF, Macdonald JE, Jones DD, Elliott M. Defined covalent assembly of protein molecules on graphene using a genetically encoded photochemical reaction handle. RSC Adv 2018; 8:5768-5775. [PMID: 35539607 PMCID: PMC9078156 DOI: 10.1039/c7ra11166e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 01/11/2018] [Indexed: 11/27/2022] Open
Abstract
We have created modified protein variants by introducing a non-canonical amino acid p-azido-l-phenylalanine (azF) into defined positions for photochemically-induced covalent attachment to graphene. Attachment of GFP, TEM and cyt b562 proteins was verified through a combination of atomic force and scanning tunnelling microscopy, resistance measurements, Raman data and fluorescence measurements. This method can in principle be extended to any protein which can be engineered in this way without adversely affecting its structural stability. We demonstrate a general method for photochemically-induced covalent attachment of proteins to graphene through the introduction of a non-canonical amino acid p-azido-l-phenylalanine into defined residue positions.![]()
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Affiliation(s)
- Athraa J. Zaki
- School of Physics and Astronomy
- Cardiff University
- Cardiff CF24 3AA
- UK
| | | | | | | | | | | | | | | | | | | | - Martin Elliott
- School of Physics and Astronomy
- Cardiff University
- Cardiff CF24 3AA
- UK
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67
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Li J, He G, Hiroshi U, Liu W, Noji H, Qi C, Guo X. Direct Measurement of Single-Molecule Adenosine Triphosphatase Hydrolysis Dynamics. ACS NANO 2017; 11:12789-12795. [PMID: 29215860 DOI: 10.1021/acsnano.7b07639] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
F1-ATPase (F1) is a bidirectional molecular motor that hydrolyzes nearly all ATPs to fuel the cellular processes. Optical observation of labeled F1 rotation against the α3β3 hexamer ring revealed the sequential mechanical rotation steps corresponding to ATP binding/ADP release and ATP hydrolysis/Pi release. These substeps originate from the F1 rotation but with heavy load on the γ shaft due to fluorescent labeling and the photophysical limitation of an optical microscope, which hampers better understanding of the intrinsic kinetic behavior of ATP hydrolysis. In this work, we present a method capable of electrically monitoring ATP hydrolysis of a single label-free F1 in real time by using a high-gain silicon nanowire-based field-effect transistor circuit. We reproducibly observe the regular current signal fluctuations with two distinct levels, which are induced by the binding dwell and the catalytic dwell, respectively, in both concentration- and temperature-dependent experiments. In comparison with labeled F1, the hydrolysis rate of nonlabeled F1 used in this study is 1 order of magnitude faster (1.69 × 108 M-1 s-1 at 20 °C), and the differences between two sequential catalytic rates are clearer, demonstrating the ability of nanowire nanocircuits to directly probe the intrinsic dynamic processes of the biological activities with single-molecule/single-event sensitivity. This approach is complementary to traditional optical methods, offering endless opportunities to unravel molecular mechanisms of a variety of dynamic biosystems under realistic physiological conditions.
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Affiliation(s)
- Jie Li
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University , Beijing 100875, P. R. China
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, P. R. China
| | - Gen He
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University , Beijing 100875, P. R. China
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, P. R. China
| | - Ueno Hiroshi
- Department of Applied Chemistry, School of Engineering, The University of Tokyo , Tokyo 113-8654, Japan
| | - Wenzhe Liu
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, P. R. China
| | - Hiroyuki Noji
- Department of Applied Chemistry, School of Engineering, The University of Tokyo , Tokyo 113-8654, Japan
| | - Chuanmin Qi
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University , Beijing 100875, P. R. China
| | - Xuefeng Guo
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University , Beijing 100871, P. R. China
- Department of Materials Science and Engineering, College of Engineering, Peking University , Beijing 100871, P. R. China
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68
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Freeley M, Worthy HL, Ahmed R, Bowen B, Watkins D, Macdonald JE, Zheng M, Jones DD, Palma M. Site-Specific One-to-One Click Coupling of Single Proteins to Individual Carbon Nanotubes: A Single-Molecule Approach. J Am Chem Soc 2017; 139:17834-17840. [PMID: 29148737 DOI: 10.1021/jacs.7b07362] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We report the site-specific coupling of single proteins to individual carbon nanotubes (CNTs) in solution and with single-molecule control. Using an orthogonal Click reaction, Green Fluorescent Protein (GFP) was engineered to contain a genetically encoded azide group and then bound to CNT ends in different configurations: in close proximity or at longer distances from the GFP's functional center. Atomic force microscopy and fluorescence analysis in solution and on surfaces at the single-protein level confirmed the importance of bioengineering optimal protein attachment sites to achieve direct protein-nanotube communication and bridging.
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Affiliation(s)
- Mark Freeley
- School of Biological and Chemical Sciences, Institute of Bioengineering, and Materials Research Institute, Queen Mary University of London , Mile End Road, London E1 4NS, United Kingdom
| | - Harley L Worthy
- Division of Molecular Biosciences, School of Biosciences, Main Building, Cardiff University , Cardiff, Wales CF10 3AX, United Kingdom
| | - Rochelle Ahmed
- Division of Molecular Biosciences, School of Biosciences, Main Building, Cardiff University , Cardiff, Wales CF10 3AX, United Kingdom
| | - Ben Bowen
- Division of Molecular Biosciences, School of Biosciences, Main Building, Cardiff University , Cardiff, Wales CF10 3AX, United Kingdom
| | - Daniel Watkins
- Division of Molecular Biosciences, School of Biosciences, Main Building, Cardiff University , Cardiff, Wales CF10 3AX, United Kingdom
| | - J Emyr Macdonald
- School of Physics and Astronomy, Cardiff University , Queens's Building, The Parade, Cardiff CF24 3AA, United Kingdom
| | - Ming Zheng
- Materials Science and Engineering Division, National Institute of Standards and Technology , 100 Bureau Drive, Gaithersburg, Maryland 20899-8542, United States
| | - D Dafydd Jones
- Division of Molecular Biosciences, School of Biosciences, Main Building, Cardiff University , Cardiff, Wales CF10 3AX, United Kingdom
| | - Matteo Palma
- School of Biological and Chemical Sciences, Institute of Bioengineering, and Materials Research Institute, Queen Mary University of London , Mile End Road, London E1 4NS, United Kingdom
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69
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He G, Li J, Qi C, Guo X. Single Nucleotide Polymorphism Genotyping in Single-Molecule Electronic Circuits. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2017; 4:1700158. [PMID: 29201610 PMCID: PMC5700462 DOI: 10.1002/advs.201700158] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 06/20/2017] [Indexed: 05/08/2023]
Abstract
Establishing low-cost, high-throughput, simple, and accurate single nucleotide polymorphism (SNP) genotyping techniques is beneficial for understanding the intrinsic relationship between individual genetic variations and their biological functions on a genomic scale. Here, a straightforward and reliable single-molecule approach is demonstrated for precise SNP authentication by directly measuring the fluctuations in electrical signals in an electronic circuit, which is fabricated from a high-gain field-effect silicon nanowire decorated with a single hairpin DNA, in the presence of different target DNAs. By simply comparing the proportion difference of a probe-target duplex structure throughout the process, this study implements allele-specific and accurate SNP detection. These results are supported by the statistical analyses of different dynamic parameters such as the mean lifetime and the unwinding probability of the duplex conformation. In comparison with conventional polymerase chain reaction and optical methods, this convenient and label-free method is complementary to existing optical methods and also shows several advantages, such as simple operation and no requirement for fluorescent labeling, thus promising a futuristic route toward the next-generation genotyping technique.
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Affiliation(s)
- Gen He
- Beijing National Laboratory for Molecular SciencesState Key Laboratory for Structural Chemistry of Unstable and Stable SpeciesCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing100871P. R. China
- Key Laboratory of RadiopharmaceuticalsMinistry of EducationCollege of ChemistryBeijing Normal UniversityBeijing100875P. R. China
| | - Jie Li
- Beijing National Laboratory for Molecular SciencesState Key Laboratory for Structural Chemistry of Unstable and Stable SpeciesCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing100871P. R. China
- Key Laboratory of RadiopharmaceuticalsMinistry of EducationCollege of ChemistryBeijing Normal UniversityBeijing100875P. R. China
| | - Chuanmin Qi
- Key Laboratory of RadiopharmaceuticalsMinistry of EducationCollege of ChemistryBeijing Normal UniversityBeijing100875P. R. China
| | - Xuefeng Guo
- Beijing National Laboratory for Molecular SciencesState Key Laboratory for Structural Chemistry of Unstable and Stable SpeciesCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing100871P. R. China
- Department of Materials Science and EngineeringCollege of EngineeringPeking UniversityBeijing100871P. R. China
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70
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Gruss D, Smolyanitsky A, Zwolak M. Communication: Relaxation-limited electronic currents in extended reservoir simulations. J Chem Phys 2017; 147:141102. [PMID: 29031250 PMCID: PMC5718372 DOI: 10.1063/1.4997022] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Open-system approaches are gaining traction in the simulation of charge transport in nanoscale and molecular electronic devices. In particular, "extended reservoir" simulations, where explicit reservoir degrees of freedom are present, allow for the computation of both real-time and steady-state properties but require relaxation of the extended reservoirs. The strength of this relaxation, γ, influences the conductance, giving rise to a "turnover" behavior analogous to Kramers turnover in chemical reaction rates. We derive explicit, general expressions for the weak and strong relaxation limits. For weak relaxation, the conductance increases linearly with γ and every electronic state of the total explicit system contributes to the electronic current according to its "reduced" weight in the two extended reservoir regions. Essentially, this represents two conductors in series-one at each interface with the implicit reservoirs that provide the relaxation. For strong relaxation, a "dual" expression-one with the same functional form-results, except now proportional to 1/γ and dependent on the system of interest's electronic states, reflecting that the strong relaxation is localizing electrons in the extended reservoirs. Higher order behavior (e.g., γ2 or 1/γ2) can occur when there is a gap in the frequency spectrum. Moreover, inhomogeneity in the frequency spacing can give rise to a pseudo-plateau regime. These findings yield a physically motivated approach to diagnosing numerical simulations and understanding the influence of relaxation, and we examine their occurrence in both simple models and a realistic, fluctuating graphene nanoribbon.
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Affiliation(s)
- Daniel Gruss
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
- Maryland Nanocenter, University of Maryland, College Park, MD 20742, USA
| | - Alex Smolyanitsky
- Applied Chemicals and Materials Division, National Institute of Standards and Technology, Boulder, CO 80305, USA
| | - Michael Zwolak
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
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71
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Setiadi A, Fujii H, Kasai S, Yamashita KI, Ogawa T, Ikuta T, Kanai Y, Matsumoto K, Kuwahara Y, Akai-Kasaya M. Room-temperature discrete-charge-fluctuation dynamics of a single molecule adsorbed on a carbon nanotube. NANOSCALE 2017; 9:10674-10683. [PMID: 28616952 DOI: 10.1039/c7nr02534c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Detection and use of physical noise fluctuations in a signal provides significant advantages in the development of bio- and neuro-sensing and functional mimicking devices. Low-dimensional carbon nanomaterials are a good candidate for use in noise generation due to the high surface sensitivity of these materials, which may themselves serve as the main building blocks of these devices. Here, we demonstrate that the addition of a molecule with high redox activity to a carbon nanotube (CNT) field-effect transistor provides tunable current fluctuation noise. A unique charge-trap state in the vicinity of the CNT surface due to the presence of the single molecule is the origin of the noise, which generates a prominent and unique slow discrete random telegraph signal in the device current. The power spectral density reveals the peculiar frequency limit of the fluctuation for different types of molecules depending on their redox activity and adsorption configuration. These results indicate that the detected noise will provide new opportunities to obtain electronic information for a single molecule combined with a nanotube surface, and that controllability of the noise may contribute to the expansion of noise utilization in future bio-inspired devices.
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Affiliation(s)
- Agung Setiadi
- Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 565-0871 Suita, Japan.
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72
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Electrostatic melting in a single-molecule field-effect transistor with applications in genomic identification. Nat Commun 2017; 8:15450. [PMID: 28516911 PMCID: PMC5454367 DOI: 10.1038/ncomms15450] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 03/29/2017] [Indexed: 01/28/2023] Open
Abstract
The study of biomolecular interactions at the single-molecule level holds great potential for both basic science and biotechnology applications. Single-molecule studies often rely on fluorescence-based reporting, with signal levels limited by photon emission from single optical reporters. The point-functionalized carbon nanotube transistor, known as the single-molecule field-effect transistor, is a bioelectronics alternative based on intrinsic molecular charge that offers significantly higher signal levels for detection. Such devices are effective for characterizing DNA hybridization kinetics and thermodynamics and enabling emerging applications in genomic identification. In this work, we show that hybridization kinetics can be directly controlled by electrostatic bias applied between the device and the surrounding electrolyte. We perform the first single-molecule experiments demonstrating the use of electrostatics to control molecular binding. Using bias as a proxy for temperature, we demonstrate the feasibility of detecting various concentrations of 20-nt target sequences from the Ebolavirus nucleoprotein gene in a constant-temperature environment. DNA hybridization of two single-strands to form a double-stranded helix is widely used for genomic identification applications. Here, Vernick et al. record duplex formation of 20-mer oligonucleotide using a single-molecule field-effect transistor, where DNA kinetics is affected by electrostatic bias.
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73
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Liu Z, Ren S, Guo X. Switching Effects in Molecular Electronic Devices. Top Curr Chem (Cham) 2017; 375:56. [PMID: 28493206 DOI: 10.1007/s41061-017-0144-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 04/25/2017] [Indexed: 10/19/2022]
Abstract
The creation of molecular electronic switches by using smart molecules is of great importance to the field of molecular electronics. This requires a fundamental understanding of the intrinsic electron transport mechanisms, which depend on several factors including the charge transport pathway, the molecule-electrode coupling strength, the energy of the molecular frontier orbitals, and the electron spin state. On the basis of significant progresses achieved in both experiments and theory over the past decade, in this review article we focus on new insights into the design and fabrication of different molecular switches and the corresponding switching effects, which is crucial to the development of molecular electronics. We summarize the strategies developed for single-molecule device fabrication and the mechanism of these switching effects. These analyses should be valuable for deeply understanding the switching effects in molecular electronic devices.
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Affiliation(s)
- Zihao Liu
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, People's Republic of China
| | - Shizhao Ren
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, People's Republic of China
| | - Xuefeng Guo
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, People's Republic of China.
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74
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Lu M, Lu HP. Revealing Multiple Pathways in T4 Lysozyme Substep Conformational Motions by Single-Molecule Enzymology and Modeling. J Phys Chem B 2017; 121:5017-5024. [DOI: 10.1021/acs.jpcb.7b03039] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Maolin Lu
- Department of Chemistry and
Center for Photochemical Sciences, Bowling Green State University, Bowling
Green, Ohio 43403, United States
| | - H. Peter Lu
- Department of Chemistry and
Center for Photochemical Sciences, Bowling Green State University, Bowling
Green, Ohio 43403, United States
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75
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Ng AL, Chen CF, Kwon H, Peng Z, Lee CS, Wang Y. Chemical Gating of a Synthetic Tube-in-a-Tube Semiconductor. J Am Chem Soc 2017; 139:3045-3051. [PMID: 28169545 PMCID: PMC5335872 DOI: 10.1021/jacs.6b12111] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
![]()
A critical challenge to translating
field effect transistors into
biochemical sensor platforms is the requirement of a gate electrode,
which imposes restrictions on sensor device architectures and results
in added expense, poorer scalability, and electrical noise. Here we
show that it is possible to eliminate the need of the physical gate
electrode and dielectrics altogether using a synthetic tube-in-a-tube
(Tube∧2) semiconductor. Composed of a semiconducting
single-walled carbon nanotube nested in a charged, impermeable covalent
functional shell, Tube∧2 allows the semiconducting
conduction pathway to be modulated solely by surface functional groups
in a chemically gated-all-around configuration. The removal of physical
gates significantly simplifies the device architecture and enables
photolithography-free, highly scalable fabrication of transistor sensors
in nonconventional configurations that are otherwise impossible. We
show that concomitant FET sensitivity and single-mismatch selectivity
can be achieved with Tube∧2 even in a two-terminal,
thin film transistor device configuration that is as simple as a chemiresistor.
Miniaturized two-terminal field effect point sensors can also be fabricated,
using a straightforward dice-and-dip procedure, for the detection
of tuberculosis biomarkers.
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Affiliation(s)
- Allen L Ng
- Department of Chemistry and Biochemistry, University of Maryland , College Park, Maryland 20742, United States
| | - Chien-Fu Chen
- Institute of Applied Mechanics, National Taiwan University , Taipei, Taiwan 106
| | - Hyejin Kwon
- Department of Chemistry and Biochemistry, University of Maryland , College Park, Maryland 20742, United States
| | - Zhiwei Peng
- Department of Chemistry and Biochemistry, University of Maryland , College Park, Maryland 20742, United States
| | - Cheng S Lee
- Department of Chemistry and Biochemistry, University of Maryland , College Park, Maryland 20742, United States
| | - YuHuang Wang
- Department of Chemistry and Biochemistry, University of Maryland , College Park, Maryland 20742, United States.,Maryland NanoCenter, University of Maryland , College Park, Maryland 20742, United States
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76
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Sheu SY, Yang DY. Mechanically Controlled Electron Transfer in a Single-Polypeptide Transistor. Sci Rep 2017; 7:39792. [PMID: 28051140 PMCID: PMC5209712 DOI: 10.1038/srep39792] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 11/28/2016] [Indexed: 02/03/2023] Open
Abstract
Proteins are of interest in nano-bio electronic devices due to their versatile structures, exquisite functionality and specificity. However, quantum transport measurements produce conflicting results due to technical limitations whereby it is difficult to precisely determine molecular orientation, the nature of the moieties, the presence of the surroundings and the temperature; in such circumstances a better understanding of the protein electron transfer (ET) pathway and the mechanism remains a considerable challenge. Here, we report an approach to mechanically drive polypeptide flip-flop motion to achieve a logic gate with ON and OFF states during protein ET. We have calculated the transmission spectra of the peptide-based molecular junctions and observed the hallmarks of electrical current and conductance. The results indicate that peptide ET follows an NC asymmetric process and depends on the amino acid chirality and α-helical handedness. Electron transmission decreases as the number of water molecules increases, and the ET efficiency and its pathway depend on the type of water-bridged H-bonds. Our results provide a rational mechanism for peptide ET and new perspectives on polypeptides as potential candidates in logic nano devices.
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Affiliation(s)
- Sheh-Yi Sheu
- Department of Life Sciences, Institute of Genome Sciences and Institute of Biomedical Informatics, National Yang-Ming University, Taipei 112, Taiwan
| | - Dah-Yen Yang
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan
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77
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Sasmal DK, Pulido LE, Kasal S, Huang J. Single-molecule fluorescence resonance energy transfer in molecular biology. NANOSCALE 2016; 8:19928-19944. [PMID: 27883140 PMCID: PMC5145784 DOI: 10.1039/c6nr06794h] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Single-molecule fluorescence resonance energy transfer (smFRET) is a powerful technique for studying the conformation dynamics and interactions of individual biomolecules. In this review, we describe the concept and principle of smFRET, illustrate general instrumentation and microscopy settings for experiments, and discuss the methods and algorithms for data analysis. Subsequently, we review applications of smFRET in protein conformational changes, ion channel open-close properties, receptor-ligand interactions, nucleic acid structure regulation, vesicle fusion, and force induced conformational dynamics. Finally, we discuss the main limitations of smFRET in molecular biology.
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Affiliation(s)
- Dibyendu K Sasmal
- The Institute for Molecular Engineering, The University of Chicago, Chicago, IL 60637, USA.
| | - Laura E Pulido
- The Institute for Molecular Engineering, The University of Chicago, Chicago, IL 60637, USA.
| | - Shan Kasal
- The Institute for Molecular Engineering, The University of Chicago, Chicago, IL 60637, USA.
| | - Jun Huang
- The Institute for Molecular Engineering, The University of Chicago, Chicago, IL 60637, USA.
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78
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Wen H, Li W, Chen J, He G, Li L, Olson MA, Sue ACH, Stoddart JF, Guo X. Complex formation dynamics in a single-molecule electronic device. SCIENCE ADVANCES 2016; 2:e1601113. [PMID: 28138528 PMCID: PMC5262467 DOI: 10.1126/sciadv.1601113] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 10/21/2016] [Indexed: 05/20/2023]
Abstract
Single-molecule electronic devices offer unique opportunities to investigate the properties of individual molecules that are not accessible in conventional ensemble experiments. However, these investigations remain challenging because they require (i) highly precise device fabrication to incorporate single molecules and (ii) sufficient time resolution to be able to make fast molecular dynamic measurements. We demonstrate a graphene-molecule single-molecule junction that is capable of probing the thermodynamic and kinetic parameters of a host-guest complex. By covalently integrating a conjugated molecular wire with a pendent crown ether into graphene point contacts, we can transduce the physical [2]pseudorotaxane (de)formation processes between the electron-rich crown ether and a dicationic guest into real-time electrical signals. The conductance of the single-molecule junction reveals two-level fluctuations that are highly dependent on temperature and solvent environments, affording a nondestructive means of quantitatively determining the binding and rate constants, as well as the activation energies, for host-guest complexes. The thermodynamic processes reveal the host-guest binding to be enthalpy-driven and are consistent with conventional 1H nuclear magnetic resonance titration experiments. This electronic device opens up a new route to developing single-molecule dynamics investigations with microsecond resolution for a broad range of chemical and biochemical applications.
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Affiliation(s)
- Huimin Wen
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Wengang Li
- Institute for Molecular Design and Synthesis, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
| | - Jiewei Chen
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Gen He
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
| | - Longhua Li
- Scientific Research Academy, Jiangsu University, Zhenjiang 212013, China
| | - Mark A. Olson
- Institute for Molecular Design and Synthesis, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
| | - Andrew C.-H. Sue
- Institute for Molecular Design and Synthesis, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
- Department of Chemistry, Northwestern University, Evanston, IL 60208–3113, USA
- Corresponding author. (X.G.); (A.C.-H.S.); (J.F.S.)
| | - J. Fraser Stoddart
- Institute for Molecular Design and Synthesis, School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China
- Department of Chemistry, Northwestern University, Evanston, IL 60208–3113, USA
- Corresponding author. (X.G.); (A.C.-H.S.); (J.F.S.)
| | - Xuefeng Guo
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
- Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China
- Corresponding author. (X.G.); (A.C.-H.S.); (J.F.S.)
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79
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Melzer K, Bhatt VD, Jaworska E, Mittermeier R, Maksymiuk K, Michalska A, Lugli P. Enzyme assays using sensor arrays based on ion-selective carbon nanotube field-effect transistors. Biosens Bioelectron 2016; 84:7-14. [DOI: 10.1016/j.bios.2016.04.077] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 04/21/2016] [Accepted: 04/22/2016] [Indexed: 11/26/2022]
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80
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Li J, He G, Ueno H, Jia C, Noji H, Qi C, Guo X. Direct real-time detection of single proteins using silicon nanowire-based electrical circuits. NANOSCALE 2016; 8:16172-16176. [PMID: 27714062 DOI: 10.1039/c6nr04103e] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We present an efficient strategy through surface functionalization to build a single silicon nanowire field-effect transistor-based biosensor that is capable of directly detecting protein adsorption/desorption at the single-event level. The step-wise signals in real-time detection of His-tag F1-ATPases demonstrate a promising electrical biosensing approach with single-molecule sensitivity, thus opening up new opportunities for studying single-molecule biophysics in broad biological systems.
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Affiliation(s)
- Jie Li
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China. and Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China.
| | - Gen He
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China. and Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China.
| | - Hiroshi Ueno
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, Tokyo 113-8654, Japan.
| | - Chuancheng Jia
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China.
| | - Hiroyuki Noji
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, Tokyo 113-8654, Japan.
| | - Chuanmin Qi
- Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China.
| | - Xuefeng Guo
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China. and Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, P. R. China
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81
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Bouilly D, Hon J, Daly NS, Trocchia S, Vernick S, Yu J, Warren S, Wu Y, Gonzalez RL, Shepard KL, Nuckolls C. Single-Molecule Reaction Chemistry in Patterned Nanowells. NANO LETTERS 2016; 16:4679-85. [PMID: 27270004 PMCID: PMC5176326 DOI: 10.1021/acs.nanolett.6b02149] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
A new approach to synthetic chemistry is performed in ultraminiaturized, nanofabricated reaction chambers. Using lithographically defined nanowells, we achieve single-point covalent chemistry on hundreds of individual carbon nanotube transistors, providing robust statistics and unprecedented spatial resolution in adduct position. Each device acts as a sensor to detect, in real-time and through quantized changes in conductance, single-point functionalization of the nanotube as well as consecutive chemical reactions, molecular interactions, and molecular conformational changes occurring on the resulting single-molecule probe. In particular, we use a set of sequential bioconjugation reactions to tether a single-strand of DNA to the device and record its repeated, reversible folding into a G-quadruplex structure. The stable covalent tether allows us to measure the same molecule in different solutions, revealing the characteristic increased stability of the G-quadruplex structure in the presence of potassium ions (K(+)) versus sodium ions (Na(+)). Nanowell-confined reaction chemistry on carbon nanotube devices offers a versatile method to isolate and monitor individual molecules during successive chemical reactions over an extended period of time.
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Affiliation(s)
- Delphine Bouilly
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027 United
States
| | - Jason Hon
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027 United
States
| | - Nathan S. Daly
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027 United
States
| | - Scott Trocchia
- Department of Electrical Engineering, Columbia University, 500 W. 120th Street, New York, New York 10027 United
States
| | - Sefi Vernick
- Department of Electrical Engineering, Columbia University, 500 W. 120th Street, New York, New York 10027 United
States
| | - Jaeeun Yu
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027 United
States
| | - Steven Warren
- Department of Electrical Engineering, Columbia University, 500 W. 120th Street, New York, New York 10027 United
States
| | - Ying Wu
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027 United
States
| | - Ruben L. Gonzalez
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027 United
States
- E-mail:
| | - Kenneth L. Shepard
- Department of Electrical Engineering, Columbia University, 500 W. 120th Street, New York, New York 10027 United
States
- E-mail:
| | - Colin Nuckolls
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027 United
States
- E-mail:
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82
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Naylor CH, Kybert NJ, Schneier C, Xi J, Romero G, Saven JG, Liu R, Charlie Johnson AT. Scalable Production of Molybdenum Disulfide Based Biosensors. ACS NANO 2016; 10:6173-9. [PMID: 27227361 PMCID: PMC4949953 DOI: 10.1021/acsnano.6b02137] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We demonstrate arrays of opioid biosensors based on chemical vapor deposition grown molybdenum disulfide (MoS2) field effect transistors (FETs) coupled to a computationally redesigned, water-soluble variant of the μ-opioid receptor (MOR). By transferring dense films of monolayer MoS2 crystals onto prefabricated electrode arrays, we obtain high-quality FETs with clean surfaces that allow for reproducible protein attachment. The fabrication yield of MoS2 FETs and biosensors exceeds 95%, with an average mobility of 2.0 cm(2) V(-1) s(-1) (36 cm(2) V(-1) s(-1)) at room temperature under ambient (in vacuo). An atomic length nickel-mediated linker chemistry enables target binding events that occur very close to the MoS2 surface to maximize sensitivity. The biosensor response calibration curve for a synthetic opioid peptide known to bind to the wild-type MOR indicates binding affinity that matches values determined using traditional techniques and a limit of detection ∼3 nM (1.5 ng/mL). The combination of scalable array fabrication and rapid, precise binding readout enabled by the MoS2 transistor offers the prospect of a solid-state drug testing platform for rapid readout of the interactions between novel drugs and their intended protein targets.
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Affiliation(s)
- Carl H. Naylor
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia 19104, United States
| | - Nicholas J. Kybert
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia 19104, United States
| | - Camilla Schneier
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia 19104, United States
| | - Jin Xi
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia 19104, United States
| | - Gabriela Romero
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia 19104, United States
| | - Jeffery G. Saven
- Department of Chemistry, University of Pennsylvania, Philadelphia 19104, United States
| | - Renyu Liu
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia 19104, United States
| | - A. T. Charlie Johnson
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia 19104, United States
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83
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Gül OT, Pugliese KM, Choi Y, Sims PC, Pan D, Rajapakse AJ, Weiss GA, Collins PG. Single Molecule Bioelectronics and Their Application to Amplification-Free Measurement of DNA Lengths. BIOSENSORS-BASEL 2016; 6:bios6030029. [PMID: 27348011 PMCID: PMC5039648 DOI: 10.3390/bios6030029] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 06/08/2016] [Accepted: 06/15/2016] [Indexed: 01/17/2023]
Abstract
As biosensing devices shrink smaller and smaller, they approach a scale in which single molecule electronic sensing becomes possible. Here, we review the operation of single-enzyme transistors made using single-walled carbon nanotubes. These novel hybrid devices transduce the motions and catalytic activity of a single protein into an electronic signal for real-time monitoring of the protein’s activity. Analysis of these electronic signals reveals new insights into enzyme function and proves the electronic technique to be complementary to other single-molecule methods based on fluorescence. As one example of the nanocircuit technique, we have studied the Klenow Fragment (KF) of DNA polymerase I as it catalytically processes single-stranded DNA templates. The fidelity of DNA polymerases makes them a key component in many DNA sequencing techniques, and here we demonstrate that KF nanocircuits readily resolve DNA polymerization with single-base sensitivity. Consequently, template lengths can be directly counted from electronic recordings of KF’s base-by-base activity. After measuring as few as 20 copies, the template length can be determined with <1 base pair resolution, and different template lengths can be identified and enumerated in solutions containing template mixtures.
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Affiliation(s)
- O Tolga Gül
- Department of Physics and Astronomy, University of California at Irvine, Irvine, CA 92697, USA
- Department of Physics, Polatlı Faculty of Science and Arts, Gazi University, Polatlı 06900, Turkey
| | - Kaitlin M Pugliese
- Department of Chemistry, University of California at Irvine, Irvine, CA 92697, USA
| | - Yongki Choi
- Department of Physics and Astronomy, University of California at Irvine, Irvine, CA 92697, USA
- Department of Physics, North Dakota State University, Fargo, ND 58108, USA
| | - Patrick C Sims
- Department of Physics and Astronomy, University of California at Irvine, Irvine, CA 92697, USA
| | - Deng Pan
- Department of Physics and Astronomy, University of California at Irvine, Irvine, CA 92697, USA
| | - Arith J Rajapakse
- Department of Physics and Astronomy, University of California at Irvine, Irvine, CA 92697, USA
| | - Gregory A Weiss
- Department of Chemistry, University of California at Irvine, Irvine, CA 92697, USA.
- Department of Molecular Biology and Biochemistry, University of California at Irvine, Irvine, CA 92697, USA.
| | - Philip G Collins
- Department of Physics and Astronomy, University of California at Irvine, Irvine, CA 92697, USA.
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84
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He G, Li J, Ci H, Qi C, Guo X. Direct Measurement of Single-Molecule DNA Hybridization Dynamics with Single-Base Resolution. Angew Chem Int Ed Engl 2016; 55:9036-40. [DOI: 10.1002/anie.201603038] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 05/08/2016] [Indexed: 11/08/2022]
Affiliation(s)
- Gen He
- Key Laboratory of Radiopharmaceuticals; Ministry of Education; College of Chemistry; Beijing Normal University; Beijing 100875 P.R. China
| | - Jie Li
- Key Laboratory of Radiopharmaceuticals; Ministry of Education; College of Chemistry; Beijing Normal University; Beijing 100875 P.R. China
| | - Haina Ci
- Beijing National Laboratory for Molecular Sciences; State Key Laboratory for Structural Chemistry of Unstable and Stable Species; College of Chemistry and Molecular Engineering; Peking University; Beijing 100871 P.R. China
| | - Chuanmin Qi
- Key Laboratory of Radiopharmaceuticals; Ministry of Education; College of Chemistry; Beijing Normal University; Beijing 100875 P.R. China
| | - Xuefeng Guo
- Beijing National Laboratory for Molecular Sciences; State Key Laboratory for Structural Chemistry of Unstable and Stable Species; College of Chemistry and Molecular Engineering; Peking University; Beijing 100871 P.R. China
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85
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He G, Li J, Ci H, Qi C, Guo X. Direct Measurement of Single-Molecule DNA Hybridization Dynamics with Single-Base Resolution. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201603038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Gen He
- Key Laboratory of Radiopharmaceuticals; Ministry of Education; College of Chemistry; Beijing Normal University; Beijing 100875 P.R. China
| | - Jie Li
- Key Laboratory of Radiopharmaceuticals; Ministry of Education; College of Chemistry; Beijing Normal University; Beijing 100875 P.R. China
| | - Haina Ci
- Beijing National Laboratory for Molecular Sciences; State Key Laboratory for Structural Chemistry of Unstable and Stable Species; College of Chemistry and Molecular Engineering; Peking University; Beijing 100871 P.R. China
| | - Chuanmin Qi
- Key Laboratory of Radiopharmaceuticals; Ministry of Education; College of Chemistry; Beijing Normal University; Beijing 100875 P.R. China
| | - Xuefeng Guo
- Beijing National Laboratory for Molecular Sciences; State Key Laboratory for Structural Chemistry of Unstable and Stable Species; College of Chemistry and Molecular Engineering; Peking University; Beijing 100871 P.R. China
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86
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Khodadadi S, Sokolov AP. Atomistic details of protein dynamics and the role of hydration water. Biochim Biophys Acta Gen Subj 2016; 1861:3546-3552. [PMID: 27155577 DOI: 10.1016/j.bbagen.2016.04.028] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 04/26/2016] [Accepted: 04/27/2016] [Indexed: 11/19/2022]
Abstract
BACKGROUND The importance of protein dynamics for their biological activity is now well recognized. Different experimental and computational techniques have been employed to study protein dynamics, hierarchy of different processes and the coupling between protein and hydration water dynamics. Yet, understanding the atomistic details of protein dynamics and the role of hydration water remains rather limited. SCOOP OF REVIEW Based on overview of neutron scattering, molecular dynamic simulations, NMR and dielectric spectroscopy results we present a general picture of protein dynamics covering time scales from faster than ps to microseconds and the influence of hydration water on different relaxation processes. MAJOR CONCLUSIONS Internal protein dynamics spread over a wide time range from faster than picosecond to longer than microseconds. We suggest that the structural relaxation in hydrated proteins appears on the microsecond time scale, while faster processes present mostly motion of side groups and some domains. Hydration water plays a crucial role in protein dynamics on all time scales. It controls the coupled protein-hydration water relaxation on 10-100ps time scale. This process defines the friction for slower protein dynamics. Analysis suggests that changes in amount of hydration water affect not only general friction, but also influence significantly the protein's energy landscape. GENERAL SIGNIFICANCE The proposed atomistic picture of protein dynamics provides deeper understanding of various relaxation processes and their hierarchy, similarity and differences between various biological macromolecules, including proteins, DNA and RNA. This article is part of a Special Issue entitled "Science for Life" Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazù and Dr. Federica Migliardo".
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Affiliation(s)
- Sheila Khodadadi
- Faculty of Applied Sciences, Delft University of Technology, Delft, The Netherlands; Delft Project management B.V., Delft University of Technology, Delft, The Netherlands
| | - Alexei P Sokolov
- Joint Institute for Neutron Sciences, University of Tennessee, Knoxville, TN, USA.
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87
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Gruss D, Velizhanin KA, Zwolak M. Landauer's formula with finite-time relaxation: Kramers' crossover in electronic transport. Sci Rep 2016; 6:24514. [PMID: 27094206 PMCID: PMC4837356 DOI: 10.1038/srep24514] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 03/30/2016] [Indexed: 12/23/2022] Open
Abstract
Landauer’s formula is the standard theoretical tool to examine ballistic transport in nano- and meso-scale junctions, but it necessitates that any variation of the junction with time must be slow compared to characteristic times of the system, e.g., the relaxation time of local excitations. Transport through structurally dynamic junctions is, however, increasingly of interest for sensing, harnessing fluctuations, and real-time control. Here, we calculate the steady-state current when relaxation of electrons in the reservoirs is present and demonstrate that it gives rise to three regimes of behavior: weak relaxation gives a contact-limited current; strong relaxation localizes electrons, distorting their natural dynamics and reducing the current; and in an intermediate regime the Landauer view of the system only is recovered. We also demonstrate that a simple equation of motion emerges, which is suitable for efficiently simulating time-dependent transport.
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Affiliation(s)
- Daniel Gruss
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.,Maryland Nanocenter, University of Maryland, College Park, MD 20742, USA.,Department of Physics, Oregon State University, Corvallis, OR 97331, USA
| | - Kirill A Velizhanin
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Michael Zwolak
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
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88
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Warren SB, Vernick S, Romano E, Shepard KL. Complementary Metal-Oxide-Semiconductor Integrated Carbon Nanotube Arrays: Toward Wide-Bandwidth Single-Molecule Sensing Systems. NANO LETTERS 2016; 16:2674-9. [PMID: 26999579 PMCID: PMC5319850 DOI: 10.1021/acs.nanolett.6b00319] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
There is strong interest in realizing genomic molecular diagnostic platforms that are label-free, electronic, and single-molecule. One attractive transducer for such efforts is the single-molecule field-effect transistor (smFET), capable of detecting a single electronic charge and realized with a point-functionalized exposed-gate one-dimensional carbon nanotube field-effect device. In this work, smFETs are integrated directly onto a custom complementary metal-oxide-semiconductor chip, which results in an array of up to 6000 devices delivering a measurement bandwidth of 1 MHz. In a first exploitation of these high-bandwidth measurement capabilities, point functionalization through electrochemical oxidation of the devices is observed with microsecond temporal resolution, which reveals complex reaction pathways with resolvable scattering signatures. High-rate random telegraph noise is detected in certain oxidized devices, further illustrating the measurement capabilities of the platform.
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Affiliation(s)
- Steven B. Warren
- Department of Electrical Engineering, Columbia University, New York, NY 10027
| | - Sefi Vernick
- Department of Electrical Engineering, Columbia University, New York, NY 10027
| | - Ethan Romano
- Department of Electrical Engineering, Columbia University, New York, NY 10027
| | - Kenneth L. Shepard
- Department of Electrical Engineering, Columbia University, New York, NY 10027
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89
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Christensen SM, Triplet MG, Rhodes C, Iwig JS, Tu HL, Stamou D, Groves JT. Monitoring the Waiting Time Sequence of Single Ras GTPase Activation Events Using Liposome Functionalized Zero-Mode Waveguides. NANO LETTERS 2016; 16:2890-5. [PMID: 27013033 PMCID: PMC5515077 DOI: 10.1021/acs.nanolett.6b00969] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Activation of small GTPases of the Ras superfamily by guanine nucleotide exchange factors (GEFs) is a key step in numerous cell signaling processes. Unveiling the detailed molecular mechanisms of GEF-GTPase signaling interactions is of great importance due to their central roles in cell biology, including critical disease states, and their potential as therapeutic targets. Here we present an assay to monitor individual Ras activation events catalyzed by single molecules of the GEF Son of Sevenless (SOS) in the natural membrane environment. The assay employs zero-mode waveguide (ZMW) nanostructures containing a single Ras-functionalized liposome. The ZMWs facilitate highly localized excitation of fluorophores in the vicinity of the liposome membrane, allowing direct observation of individual Ras activation events as single SOS enzymes catalyze exchange of unlabeled nucleotides bound to Ras with fluorescently labeled nucleotides from solution. The system is compatible with continuous recording of long sequences of individual enzymatic turnover events over hour-long time scales. The single turnover waiting time sequence is a molecular footprint that details the temporal characteristics of the system. Data reported here reveal long-lived activity states that correspond to well-defined conformers of SOS at the membrane. Liposome functionalized ZMWs allow for studies of nucleotide exchange reactions at single GTPase resolution, providing a platform to gauge the mechanisms of these processes.
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Affiliation(s)
- Sune M. Christensen
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Meredith G. Triplet
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Christopher Rhodes
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Jeffrey S. Iwig
- Howard Hughes Medical Institute, Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, United States
| | - Hsiung-Lin Tu
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Dimitrios Stamou
- Department of Chemistry and Nano-Science Center, University of Copenhagen, Copenhagen, Denmark
| | - Jay T. Groves
- Department of Chemistry, University of California, Berkeley, California 94720, United States
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90
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Xiang D, Wang X, Jia C, Lee T, Guo X. Molecular-Scale Electronics: From Concept to Function. Chem Rev 2016; 116:4318-440. [DOI: 10.1021/acs.chemrev.5b00680] [Citation(s) in RCA: 816] [Impact Index Per Article: 102.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Dong Xiang
- Beijing
National Laboratory for Molecular Sciences, State Key Laboratory for
Structural Chemistry of Unstable and Stable Species, College of Chemistry
and Molecular Engineering, Peking University, Beijing 100871, China
- Key
Laboratory of Optical Information Science and Technology, Institute
of Modern Optics, College of Electronic Information and Optical Engineering, Nankai University, Tianjin 300071, China
| | - Xiaolong Wang
- Beijing
National Laboratory for Molecular Sciences, State Key Laboratory for
Structural Chemistry of Unstable and Stable Species, College of Chemistry
and Molecular Engineering, Peking University, Beijing 100871, China
| | - Chuancheng Jia
- Beijing
National Laboratory for Molecular Sciences, State Key Laboratory for
Structural Chemistry of Unstable and Stable Species, College of Chemistry
and Molecular Engineering, Peking University, Beijing 100871, China
| | - Takhee Lee
- Department
of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 08826, Korea
| | - Xuefeng Guo
- Beijing
National Laboratory for Molecular Sciences, State Key Laboratory for
Structural Chemistry of Unstable and Stable Species, College of Chemistry
and Molecular Engineering, Peking University, Beijing 100871, China
- Department
of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China
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91
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Chen JL, Yang Y, Zhang LL, Liang H, Huber T, Su XC, Otting G. Analysis of the solution conformations of T4 lysozyme by paramagnetic NMR spectroscopy. Phys Chem Chem Phys 2016; 18:5850-9. [DOI: 10.1039/c5cp07196h] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Paramagnetic data show that the average structure of T4-lysozyme in solution is more open than its crystal structure.
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Affiliation(s)
- Jia-Liang Chen
- State Key Laboratory of Elemento-organic Chemistry
- The Collaborative Innovation Center of Chemical Science and Engineering (Tianjin)
- Nankai University
- Tianjin 300071
- China
| | - Yin Yang
- State Key Laboratory of Elemento-organic Chemistry
- The Collaborative Innovation Center of Chemical Science and Engineering (Tianjin)
- Nankai University
- Tianjin 300071
- China
| | - Lin-Lin Zhang
- State Key Laboratory of Elemento-organic Chemistry
- The Collaborative Innovation Center of Chemical Science and Engineering (Tianjin)
- Nankai University
- Tianjin 300071
- China
| | - Haobo Liang
- Research School of Chemistry
- Australian National University
- Canberra
- Australia
| | - Thomas Huber
- Research School of Chemistry
- Australian National University
- Canberra
- Australia
| | - Xun-Cheng Su
- State Key Laboratory of Elemento-organic Chemistry
- The Collaborative Innovation Center of Chemical Science and Engineering (Tianjin)
- Nankai University
- Tianjin 300071
- China
| | - Gottfried Otting
- Research School of Chemistry
- Australian National University
- Canberra
- Australia
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92
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Deniz AA. Deciphering Complexity in Molecular Biophysics with Single-Molecule Resolution. J Mol Biol 2015; 428:301-307. [PMID: 26707199 DOI: 10.1016/j.jmb.2015.12.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 12/16/2015] [Accepted: 12/16/2015] [Indexed: 01/12/2023]
Abstract
The structural features and dynamics of biological macromolecules underlie the molecular biology and correct functioning of cells. However, heterogeneity and other complexity of these molecules and their interactions often lead to loss of important information in traditional biophysical experiments. Single-molecule methods have dramatically altered the conceptual thinking and experimental tests available for such studies, leveraging their ability to avoid ensemble averaging. Here, I discuss briefly the rise of fluorescence single-molecule methods over the past two decades, a few key applications, and end with a view to challenges and future prospects.
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Affiliation(s)
- Ashok A Deniz
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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93
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Zuccaro L, Tesauro C, Kurkina T, Fiorani P, Yu HK, Knudsen BR, Kern K, Desideri A, Balasubramanian K. Real-Time Label-Free Direct Electronic Monitoring of Topoisomerase Enzyme Binding Kinetics on Graphene. ACS NANO 2015; 9:11166-76. [PMID: 26445172 DOI: 10.1021/acsnano.5b05709] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Monolayer graphene field-effect sensors operating in liquid have been widely deployed for detecting a range of analyte species often under equilibrium conditions. Here we report on the real-time detection of the binding kinetics of the essential human enzyme, topoisomerase I interacting with substrate molecules (DNA probes) that are immobilized electrochemically on to monolayer graphene strips. By monitoring the field-effect characteristics of the graphene biosensor in real-time during the enzyme-substrate interactions, we are able to decipher the surface binding constant for the cleavage reaction step of topoisomerase I activity in a label-free manner. Moreover, an appropriate design of the capture probes allows us to distinctly follow the cleavage step of topoisomerase I functioning in real-time down to picomolar concentrations. The presented results are promising for future rapid screening of drugs that are being evaluated for regulating enzyme activity.
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Affiliation(s)
- Laura Zuccaro
- Max Planck Institute for Solid State Research , D-70569 Stuttgat, Germany
- Department of Biology, University of Rome Tor Vergata , I-00133 Rome, Italy
| | - Cinzia Tesauro
- Department of Biology, University of Rome Tor Vergata , I-00133 Rome, Italy
- Department of Molecular Biology & Genetics, Aarhus University , DK-8000 Aarhus, Denmark
| | - Tetiana Kurkina
- Max Planck Institute for Solid State Research , D-70569 Stuttgat, Germany
| | - Paola Fiorani
- Department of Biology, University of Rome Tor Vergata , I-00133 Rome, Italy
- Institute of Translational Pharmacology , National Research Council CNR, I-00133 Rome, Italy
| | - Hak Ki Yu
- Max Planck Institute for Biophysical Chemistry , 37077 Göttingen, Germany
| | - Birgitta R Knudsen
- Department of Molecular Biology & Genetics, Aarhus University , DK-8000 Aarhus, Denmark
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University , DK-8000 Aarhus, Denmark
| | - Klaus Kern
- Max Planck Institute for Solid State Research , D-70569 Stuttgat, Germany
- Institut de Physique de la Matière Condensée, École Polytechnique Fédérale de Lausanne , CH-1015 Lausanne, Switzerland
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94
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Ping J, Xi J, Saven JG, Liu R, Johnson ATC. Quantifying the effect of ionic screening with protein-decorated graphene transistors. Biosens Bioelectron 2015; 89:689-692. [PMID: 26626969 DOI: 10.1016/j.bios.2015.11.052] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2015] [Revised: 11/03/2015] [Accepted: 11/17/2015] [Indexed: 10/22/2022]
Abstract
Liquid-based applications of biomolecule-decorated field-effect transistors (FETs) range from biosensors to in vivo implants. A critical scientific challenge is to develop a quantitative understanding of the gating effect of charged biomolecules in ionic solution and how this influences the readout of the FETs. To address this issue, we fabricated protein-decorated graphene FETs and measured their electrical properties, specifically the shift in Dirac voltage, in solutions of varying ionic strength. We found excellent quantitative agreement with a model that accounts for both the graphene polarization charge and ionic screening of ions adsorbed on the graphene as well as charged amino acids associated with the immobilized protein. The technique and analysis presented here directly couple the charging status of bound biomolecules to readout of liquid-phase FETs fabricated with graphene or other two-dimensional materials.
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Affiliation(s)
- Jinglei Ping
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia 19104, USA
| | - Jin Xi
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Jeffery G Saven
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Renyu Liu
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - A T Charlie Johnson
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia 19104, USA.
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95
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Roh JH. Dynamics of Biopolymers: Role of Hydration and Electrostatic Interactions. MACROMOL CHEM PHYS 2015. [DOI: 10.1002/macp.201500279] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Joon Ho Roh
- Institute for Basic Science; Center for Self-Assembly and Complexity; 77 Cheongam-Ro Nam-gu Pohang 790-784 South Korea
- Biomolecular Science; University of Science and Technology; 217 Gajeong-ro Yuseong-gu Daejeon 305-350 South Korea
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96
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Single-molecule spectroscopy exposes hidden states in an enzymatic electron relay. Nat Commun 2015; 6:8624. [PMID: 26468675 PMCID: PMC4634331 DOI: 10.1038/ncomms9624] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 09/12/2015] [Indexed: 01/15/2023] Open
Abstract
The ability to query enzyme molecules individually is transforming our view of catalytic mechanisms. Quiescin sulfhydryl oxidase (QSOX) is a multidomain catalyst of disulfide-bond formation that relays electrons from substrate cysteines through two redox-active sites to molecular oxygen. The chemical steps in electron transfer have been delineated, but the conformational changes accompanying these steps are poorly characterized. Here we use single-molecule Förster resonance energy transfer (smFRET) to probe QSOX conformation in resting and cycling enzyme populations. We report the discovery of unanticipated roles for conformational changes in QSOX beyond mediating electron transfer between redox-active sites. In particular, a state of the enzyme not previously postulated or experimentally detected is shown to gate, via a conformational transition, the entrance into a sub-cycle within an expanded QSOX kinetic scheme. By tightly constraining mechanistic models, smFRET data can reveal the coupling between conformational and chemical transitions in complex enzymatic cycles. A major challenge in following electron transfer through dithiol/disulfide exchange is the dearth of accompanying spectroscopic effects. Here, the authors use single-molecule Förster resonance energy transfer experiments to illuminate disulfide bond rearrangements within the enzyme quiescin sulfhydryl oxidase.
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97
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Jia C, Ma B, Xin N, Guo X. Carbon Electrode-Molecule Junctions: A Reliable Platform for Molecular Electronics. Acc Chem Res 2015; 48:2565-75. [PMID: 26190024 DOI: 10.1021/acs.accounts.5b00133] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The development of reliable approaches to integrate individual or a small collection of molecules into electrical nanocircuits, often termed "molecular electronics", is currently a research focus because it can not only overcome the increasing difficulties and fundamental limitations of miniaturization of current silicon-based electronic devices, but can also enable us to probe and understand the intrinsic properties of materials at the atomic- and/or molecular-length scale. This development might also lead to direct observation of novel effects and fundamental discovery of physical phenomena that are not accessible by traditional materials or approaches. Therefore, researchers from a variety of backgrounds have been devoting great effort to this objective, which has started to move beyond simple descriptions of charge transport and branch out in different directions, reflecting the interdisciplinarity. This Account exemplifies our ongoing interest and great effort in developing efficient lithographic methodologies capable of creating molecular electronic devices through the combination of top-down micro/nanofabrication with bottom-up molecular assembly. These devices use nanogapped carbon nanomaterials (such as single-walled carbon nanotubes (SWCNTs) and graphene), with a particular focus on graphene, as point contacts formed by electron beam lithography and precise oxygen plasma etching. Through robust amide linkages, functional molecular bridges terminated with diamine moieties are covalently wired into the carboxylic acid-functionalized nanogaps to form stable carbon electrode-molecule junctions with desired functionalities. At the macroscopic level, to improve the contact interface between electrodes and organic semiconductors and lower Schottky barriers, we used SWCNTs and graphene as efficient electrodes to explore the intrinsic properties of organic thin films, and then build functional high-performance organic nanotransistors with ultrahigh responsivities. At the molecular level, to form robust covalent bonds between electrodes and molecules and improve device stability, we developed a reliable system to immobilize individual molecules within a nanoscale gap of either SWCNTs or graphene through covalent amide bond formation, thus affording two classes of carbon electrode-molecule single-molecule junctions. One unique feature of these devices is the fact that they contain only one or two molecules as conductive elements, thus forming the basis for building new classes of chemo/biosensors with ultrahigh sensitivity. We have used these approaches to reveal the dependence of the charge transport of individual metallo-DNA duplexes on π-stacking integrity, and fabricate molecular devices capable of realizing label-free, real-time electrical detection of biological interactions at the single-event level, or switching their molecular conductance upon exposure to external stimuli, such as ion, pH, and light. These investigations highlight the unique advantages and importance of these universal methodologies to produce functional carbon electrode-molecule junctions in current and future researches toward the development of practical molecular devices, thus offering a reliable platform for molecular electronics and the promise of a new generation of multifunctional integrated circuits and sensors.
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Affiliation(s)
- Chuancheng Jia
- Center
for Nanochemistry, Beijing National Laboratory for Molecular Sciences,
State Key Laboratory for Structural Chemistry of Unstable and Stable
Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
| | - Bangjun Ma
- Center
for Nanochemistry, Beijing National Laboratory for Molecular Sciences,
State Key Laboratory for Structural Chemistry of Unstable and Stable
Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
| | - Na Xin
- Center
for Nanochemistry, Beijing National Laboratory for Molecular Sciences,
State Key Laboratory for Structural Chemistry of Unstable and Stable
Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
| | - Xuefeng Guo
- Center
for Nanochemistry, Beijing National Laboratory for Molecular Sciences,
State Key Laboratory for Structural Chemistry of Unstable and Stable
Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
- Department
of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, P. R. China
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98
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An on-chip electrical transport spectroscopy approach for in situ monitoring electrochemical interfaces. Nat Commun 2015; 6:7867. [PMID: 26245937 PMCID: PMC4918314 DOI: 10.1038/ncomms8867] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2015] [Accepted: 06/21/2015] [Indexed: 11/16/2022] Open
Abstract
In situ monitoring electrochemical interfaces is crucial for fundamental understanding and continued optimization of electrocatalysts. Conventional spectroscopic techniques are generally difficult to implement for in situ electrochemical studies. Here we report an on-chip electrical transport spectroscopy approach for directly probing the electrochemical surfaces of metallic nanocatalysts in action. With a four-electrode device configuration, we demonstrate that the electrical properties of ultrafine platinum nanowires are highly sensitive and selective to the electrochemical surface states, enabling a nanoelectronic signalling pathway that reveals electrochemical interface information during in-device cyclic voltammetry. Our results not only show a high degree of consistency with generally accepted conclusions in platinum electrochemistry but also offer important insights on various practically important electrochemical reactions. This study defines a nanoelectronic strategy for in situ electrochemical surface studies with high surface sensitivity and surface specificity. In situ probing electrochemical interfaces is important for the development of improved electrocatalysts. Here, the authors present an on-chip electrical transport spectroscopy approach, which enables in situ monitoring the dynamic electrochemical interface characteristics.
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99
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Pugliese KM, Gul OT, Choi Y, Olsen TJ, Sims PC, Collins PG, Weiss GA. Processive Incorporation of Deoxynucleoside Triphosphate Analogs by Single-Molecule DNA Polymerase I (Klenow Fragment) Nanocircuits. J Am Chem Soc 2015; 137:9587-94. [PMID: 26147714 DOI: 10.1021/jacs.5b02074] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
DNA polymerases exhibit a surprising tolerance for analogs of deoxyribonucleoside triphosphates (dNTPs), despite the enzymes' highly evolved mechanisms for the specific recognition and discrimination of native dNTPs. Here, individual DNA polymerase I Klenow fragment (KF) molecules were tethered to a single-walled carbon nanotube field-effect transistor (SWCNT-FET) to investigate accommodation of dNTP analogs with single-molecule resolution. Each base incorporation accompanied a change in current with its duration defined by τclosed. Under Vmax conditions, the average time of τclosed was similar for all analog and native dNTPs (0.2 to 0.4 ms), indicating no kinetic impact on this step due to analog structure. Accordingly, the average rates of dNTP analog incorporation were largely determined by durations with no change in current defined by τopen, which includes molecular recognition of the incoming dNTP. All α-thio-dNTPs were incorporated more slowly, at 40 to 65% of the rate for the corresponding native dNTPs. During polymerization with 6-Cl-2APTP, 2-thio-dTTP, or 2-thio-dCTP, the nanocircuit uncovered an alternative conformation represented by positive current excursions that does not occur with native dNTPs. A model consistent with these results invokes rotations by the enzyme's O-helix; this motion can test the stability of nascent base pairs using nonhydrophilic interactions and is allosterically coupled to charged residues near the site of SWCNT attachment. This model with two opposing O-helix motions differs from the previous report in which all current excursions were solely attributed to global enzyme closure and covalent-bond formation. The results suggest the enzyme applies a dynamic stability-checking mechanism for each nascent base pair.
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Affiliation(s)
- Kaitlin M Pugliese
- Departments of †Chemistry, §Physics and Astronomy, and ⊥Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
| | - O Tolga Gul
- Departments of †Chemistry, §Physics and Astronomy, and ⊥Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
| | - Yongki Choi
- Departments of †Chemistry, §Physics and Astronomy, and ⊥Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
| | - Tivoli J Olsen
- Departments of †Chemistry, §Physics and Astronomy, and ⊥Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
| | - Patrick C Sims
- Departments of †Chemistry, §Physics and Astronomy, and ⊥Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
| | - Philip G Collins
- Departments of †Chemistry, §Physics and Astronomy, and ⊥Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
| | - Gregory A Weiss
- Departments of †Chemistry, §Physics and Astronomy, and ⊥Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
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100
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Khodadadi S, Sokolov AP. Protein dynamics: from rattling in a cage to structural relaxation. SOFT MATTER 2015; 11:4984-4998. [PMID: 26027652 DOI: 10.1039/c5sm00636h] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We present an overview of protein dynamics based mostly on results of neutron scattering, dielectric relaxation spectroscopy and molecular dynamics simulations. We identify several major classes of protein motions on the time scale from faster than picoseconds to several microseconds, and discuss the coupling of these processes to solvent dynamics. Our analysis suggests that the microsecond backbone relaxation process might be the main structural relaxation of the protein that defines its glass transition temperature, while faster processes present some localized secondary relaxations. Based on the overview, we formulate a general picture of protein dynamics and discuss the challenges in this field.
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Affiliation(s)
- S Khodadadi
- Faculty of Applied Sciences, Delft University of Technology, Delft, The Netherlands
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