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Roldán-Piñero C, Romero-Muñiz C, Díez-Pérez I, Vilhena JG, Pérez R, Cuevas JC, Zotti LA. Efficient Electron Hopping Transport through Azurin-Based Junctions. J Phys Chem Lett 2023; 14:11242-11249. [PMID: 38059566 PMCID: PMC10726356 DOI: 10.1021/acs.jpclett.3c02702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 10/27/2023] [Accepted: 11/09/2023] [Indexed: 12/08/2023]
Abstract
We conducted a theoretical study of electron transport through junctions of the blue-copper azurin from Pseudomonas aeruginosa. We found that single-site hopping can lead to either higher or lower current values compared to fully coherent transport. This depends on the structural details of the junctions as well as the alignment of the protein orbitals. Moreover, we show how the asymmetry of the IV curves can be affected by the position of the tip in the junction and that, under specific conditions, such a hopping mechanism is consistent with a fairly low temperature dependence of the current. Finally, we show that increasing the number of hopping sites leads to higher hopping currents. Our findings, from fully quantum calculations, provide deep insight to help guide the interpretation of experimental IV curves on highly complex systems.
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Affiliation(s)
- Carlos Roldán-Piñero
- Departamento
de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Carlos Romero-Muñiz
- Departamento
de Física de la Materia Condensada, Universidad de Sevilla, PO Box 1065, 41080 Sevilla, Spain
| | - Ismael Díez-Pérez
- Department
of Chemistry, Faculty of Natural & Mathematical Sciences, King’s College London, Britannia House, 7 Trinity Street, London SE1 1DB, U.K.
| | - J. G. Vilhena
- Departamento
de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
- Condensed
Matter Physics Center (IFIMAC), Universidad
Autónoma de Madrid, E-28049 Madrid, Spain
| | - Rubén Pérez
- Departamento
de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
- Condensed
Matter Physics Center (IFIMAC), Universidad
Autónoma de Madrid, E-28049 Madrid, Spain
| | - Juan Carlos Cuevas
- Departamento
de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
- Condensed
Matter Physics Center (IFIMAC), Universidad
Autónoma de Madrid, E-28049 Madrid, Spain
| | - Linda A. Zotti
- Departamento
de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
- Condensed
Matter Physics Center (IFIMAC), Universidad
Autónoma de Madrid, E-28049 Madrid, Spain
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2
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López-Ortiz M, Zamora RA, Giannotti MI, Gorostiza P. The Protein Matrix of Plastocyanin Supports Long-Distance Charge Transport with Photosystem I and the Copper Ion Regulates Its Spatial Span and Conductance. ACS NANO 2023; 17:20334-20344. [PMID: 37797170 DOI: 10.1021/acsnano.3c06390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/07/2023]
Abstract
Charge exchange is the fundamental process that sustains cellular respiration and photosynthesis by shuttling electrons in a cascade of electron transfer (ET) steps between redox cofactors. While intraprotein charge exchange is well characterized in protein complexes bearing multiple redox sites, interprotein processes are less understood due to the lack of suitable experimental approaches and the dynamic nature of the interactions. Proteins constrained between electrodes are known to support electron transport (ETp) through the protein matrix even without redox cofactors, as the charges housed by the redox sites in ET are furnished by the electrodes. However, it is unknown whether protein ETp mechanisms apply to the interprotein medium present under physiological conditions. We study interprotein charge exchange between plant photosystem I (PSI) and its soluble redox partner plastocyanin (Pc) and address the role of the Pc copper center. Using electrochemical scanning tunneling spectroscopy (ECSTS) current-distance and blinking measurements, we quantify the spatial span of charge exchange between individual Pc/PSI pairs and ETp through transient Pc/PSI complexes. Pc devoid of the redox center (Pcapo) can exchange charge with PSI at longer distances than with the copper ion (Pcholo). Conductance bursts associated with Pcapo/PSI complex formation are higher than in Pcholo/PSI. Thus, copper ions are not required for long-distance Pc/PSI ETp but regulate its spatial span and conductance. Our results suggest that the redox center that carries the charge in Pc is not necessary to exchange it in interprotein ET through the aqueous solution and question the canonical view of tight complex binding between redox protein partners.
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Affiliation(s)
- Manuel López-Ortiz
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona 08028, Spain
- CIBER-BBN, ISCIII, Barcelona 08028, Spain
| | - Ricardo A Zamora
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona 08028, Spain
- CIBER-BBN, ISCIII, Barcelona 08028, Spain
| | - Marina I Giannotti
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona 08028, Spain
- CIBER-BBN, ISCIII, Barcelona 08028, Spain
- Department of Materials Science and Physical Chemistry, University of Barcelona, Martí i Franquès 1-11, Barcelona 08028, Spain
| | - Pau Gorostiza
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona 08028, Spain
- CIBER-BBN, ISCIII, Barcelona 08028, Spain
- Catalan Institution for Research and Advanced Studies (ICREA), Barcelona 08010, Spain
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3
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Krishnan S, Aksimentiev A, Lindsay S, Matyushov D. Long-Range Conductivity in Proteins Mediated by Aromatic Residues. ACS PHYSICAL CHEMISTRY AU 2023; 3:444-455. [PMID: 37780537 PMCID: PMC10540285 DOI: 10.1021/acsphyschemau.3c00017] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 05/18/2023] [Accepted: 05/19/2023] [Indexed: 09/30/2023]
Abstract
Single-molecule measurements show that many proteins, lacking any redox cofactors, nonetheless exhibit electrical conductance on the order of a nanosiemen over 10 nm distances, implying that electrons can transit an entire protein in less than a nanosecond when subject to a potential difference of less than 1 V. This is puzzling because, for fast transport (i.e., a free energy barrier of zero), the hopping rate is determined by the reorganization energy of approximately 0.8 eV, and this sets the time scale of a single hop to at least 1 μs. Furthermore, the Fermi energies of typical metal electrodes are far removed from the energies required for sequential oxidation and reduction of the aromatic residues of the protein, which should further reduce the hopping current. Here, we combine all-atom molecular dynamics (MD) simulations of non-redox-active proteins (consensus tetratricopeptide repeats) with an electron transfer theory to demonstrate a molecular mechanism that can account for the unexpectedly fast electron transport. According to our MD simulations, the reorganization energy produced by the energy shift on charging (the Stokes shift) is close to the conventional value of 0.8 eV. However, the non-ergodic sampling of molecular configurations by the protein results in reaction-reorganization energies, extracted directly from the distribution of the electrostatic energy fluctuations, that are only ∼0.2 eV, which is small enough to enable long-range conductivity, without invoking quantum coherent transport. Using the MD values of the reorganization energies, we calculate a current decay with distance that is in agreement with experiment.
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Affiliation(s)
- Siddharth Krishnan
- Department
of Physics and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Aleksei Aksimentiev
- Department
of Physics and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Stuart Lindsay
- Department
of Physics, Arizona State University, Tempe, Arizona 85281, United States
- School
of Molecular Sciences, Arizona State University, Tempe, Arizona 85281, United States
- Biodesign
Institute, Arizona State University, Tempe, Arizona 85281, United States
| | - Dmitry Matyushov
- Department
of Physics, Arizona State University, Tempe, Arizona 85281, United States
- School
of Molecular Sciences, Arizona State University, Tempe, Arizona 85281, United States
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4
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Jiang T, Zeng BF, Zhang B, Tang L. Single-molecular protein-based bioelectronics via electronic transport: fundamentals, devices and applications. Chem Soc Rev 2023; 52:5968-6002. [PMID: 37498342 DOI: 10.1039/d2cs00519k] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2023]
Abstract
Biomolecular electronics is a rapidly growing multidisciplinary field that combines biology, nanoscience, and engineering to bridge the two important fields of life sciences and molecular electronics. Proteins are remarkable for their ability to recognize molecules and transport electrons, making the integration of proteins into electronic devices a long sought-after goal and leading to the emergence of the field of protein-based bioelectronics, also known as proteotronics. This field seeks to design and create new biomolecular electronic platforms that allow for the understanding and manipulation of protein-mediated electronic charge transport and related functional applications. In recent decades, there have been numerous reports on protein-based bioelectronics using a variety of nano-gapped electrical devices and techniques at the single molecular level, which are not achievable with conventional ensemble approaches. This review focuses on recent advances in physical electron transport mechanisms, device fabrication methodologies, and various applications in protein-based bioelectronics. We discuss the most recent progress of the single or few protein-bridged electrical junction fabrication strategies, summarise the work on fundamental and functional applications of protein bioelectronics that enable high and dynamic electron transport, and highlight future perspectives and challenges that still need to be addressed. We believe that this specific review will stimulate the interdisciplinary research of topics related to protein-related bioelectronics, and open up new possibilities for single-molecule biophysics and biomedicine.
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Affiliation(s)
- Tao Jiang
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, China.
| | - Biao-Feng Zeng
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, China.
| | - Bintian Zhang
- Shenzhen Key Laboratory of Precision Measurement and Early Warning Technology for Urban Environmental Health Risks, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
| | - Longhua Tang
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, China.
- Institute of Quantum Sensing, Interdisciplinary Centre for Quantum Information, Zhejiang University, Hangzhou 310027, China
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5
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Mostajabi Sarhangi S, Matyushov DV. Electron Tunneling in Biology: When Does it Matter? ACS OMEGA 2023; 8:27355-27365. [PMID: 37546584 PMCID: PMC10399179 DOI: 10.1021/acsomega.3c02719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 07/11/2023] [Indexed: 08/08/2023]
Abstract
Electrons can tunnel between cofactor molecules positioned along biological electron transport chains up to a distance of ≃ 20 Å on the millisecond time scale of enzymatic turnover. This tunneling range determines the design of biological energy chains facilitating the cross-membrane transport of electrons. Tunneling distance and cofactors' redox potentials become the main physical parameters affecting the rate of electron transport. In addition, universal charge-transport properties are assigned to all proteins, making protein identity, flexibility, and dynamics insignificant. This paradigm is challenged by dynamical models of electron transfer, showing that the electron hopping rate is constant within the crossover distance R* ≃ 12 Å, followed with an exponential falloff at longer distances. If this hypothesis is fully confirmed, natural and man-made energy chains for electron transport should be best designed by placing redox cofactors near the crossover distance R*. Protein flexibility and dynamics affect the magnitude of the maximum hopping rate within the crossover distance. Changes in protein flexibility between forward and backward transitions contribute to vectorial charge transport. For biological energy chains, charge transport through proteins is not defined by universal parameters, and protein identity matters.
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6
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Jiang T, Yi L, Liu X, Ivanov AP, Edel JB, Tang L. Fabrication of electron tunneling probes for measuring single-protein conductance. Nat Protoc 2023; 18:2579-2599. [PMID: 37420088 DOI: 10.1038/s41596-023-00846-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 04/21/2023] [Indexed: 07/09/2023]
Abstract
Studying the electrical properties of individual proteins is a prominent research area in the field of bioelectronics. Electron tunnelling or quantum mechanical tunnelling (QMT) probes can act as powerful tools for investigating the electrical properties of proteins. However, current fabrication methods for these probes often have limited reproducibility, unreliable contact or inadequate binding of proteins onto the electrodes, so better solutions are required. Here, we detail a generalizable and straightforward set of instructions for fabricating simple, nanopipette-based, tunnelling probes, suitable for measuring conductance in single proteins. Our QMT probe is based on a high-aspect-ratio dual-channel nanopipette that integrates a pair of gold tunneling electrodes with a gap of less than 5 nm, fabricated via the pyrolytic deposition of carbon followed by the electrochemical deposition of gold. The gold tunneling electrodes can be functionalized using an extensive library of available surface modifications to achieve single-protein-electrode contact. We use a biotinylated thiol modification, in which a biotin-streptavidin-biotin bridge is used to form the single-protein junction. The resulting protein-coupled QMT probes enable the stable electrical measurement of the same single protein in solution for up to several hours. We also describe the analysis method used to interpret time-dependent single-protein conductance measurements, which can provide essential information for understanding electron transport and exploring protein dynamics. The total time required to complete the protocol is ~33 h and it can be carried out by users trained in less than 24 h.
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Affiliation(s)
- Tao Jiang
- State Key Laboratory of Modern Optical Instrumentation, Institute of Quantum Sensing, Interdisciplinary Centre for Quantum Information, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, China
| | - Long Yi
- Department of Chemistry, Molecular Science Research Hub, Imperial College London, London, UK
| | - Xu Liu
- State Key Laboratory of Modern Optical Instrumentation, Institute of Quantum Sensing, Interdisciplinary Centre for Quantum Information, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, China
| | - Aleksandar P Ivanov
- Department of Chemistry, Molecular Science Research Hub, Imperial College London, London, UK
| | - Joshua B Edel
- Department of Chemistry, Molecular Science Research Hub, Imperial College London, London, UK
| | - Longhua Tang
- State Key Laboratory of Modern Optical Instrumentation, Institute of Quantum Sensing, Interdisciplinary Centre for Quantum Information, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, China.
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7
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Li T, Bandari VK, Schmidt OG. Molecular Electronics: Creating and Bridging Molecular Junctions and Promoting Its Commercialization. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2209088. [PMID: 36512432 DOI: 10.1002/adma.202209088] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 11/28/2022] [Indexed: 06/02/2023]
Abstract
Molecular electronics is driven by the dream of expanding Moore's law to the molecular level for next-generation electronics through incorporating individual or ensemble molecules into electronic circuits. For nearly 50 years, numerous efforts have been made to explore the intrinsic properties of molecules and develop diverse fascinating molecular electronic devices with the desired functionalities. The flourishing of molecular electronics is inseparable from the development of various elegant methodologies for creating nanogap electrodes and bridging the nanogap with molecules. This review first focuses on the techniques for making lateral and vertical nanogap electrodes by breaking, narrowing, and fixed modes, and highlights their capabilities, applications, merits, and shortcomings. After summarizing the approaches of growing single molecules or molecular layers on the electrodes, the methods of constructing a complete molecular circuit are comprehensively grouped into three categories: 1) directly bridging one-molecule-electrode component with another electrode, 2) physically bridging two-molecule-electrode components, and 3) chemically bridging two-molecule-electrode components. Finally, the current state of molecular circuit integration and commercialization is discussed and perspectives are provided, hoping to encourage the community to accelerate the realization of fully scalable molecular electronics for a new era of integrated microsystems and applications.
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Affiliation(s)
- Tianming Li
- Research Center for Materials, Architectures and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, 09126, Chemnitz, Germany
- Material Systems for Nanoelectronics, Chemnitz University of Technology, 09111, Chemnitz, Germany
| | - Vineeth Kumar Bandari
- Research Center for Materials, Architectures and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, 09126, Chemnitz, Germany
- Material Systems for Nanoelectronics, Chemnitz University of Technology, 09111, Chemnitz, Germany
| | - Oliver G Schmidt
- Research Center for Materials, Architectures and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, 09126, Chemnitz, Germany
- Material Systems for Nanoelectronics, Chemnitz University of Technology, 09111, Chemnitz, Germany
- Nanophysics, Dresden University of Technology, 01069, Dresden, Germany
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8
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Toren Y, Vilan A, Amdursky N. Solid-State Electron Transport Through Carbon Dots Junctions: The Role of Boron and Phosphorus Doping. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023:e2301371. [PMID: 36932877 DOI: 10.1002/smll.202301371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Indexed: 06/18/2023]
Abstract
Carbon dots (CDs) are a new class of nanoparticles that gained widespread attention recently because of their easy preparation, water solubility, biocompatibility, and bright luminescence, leading to their integration in various applications. Despite their nm-scale and proven electron transfer capabilities, the solid-state electron transport (ETp) across single CDs was never explored. Here, a molecular junction configuration is used to explore the ETp across CDs as a function of their chemical structure using both DC-bias current-voltage and AC-bias impedance measurements. CDs are used with Nitrogen and Sulfur as exogenous atoms and doped with small amounts of Boron and Phosphorous. It is shown that the presence of P and B highly improves the ETp efficiency across the CDs, yet without an indication of a change in the dominant charge carrier. Instead, structural characterizations reveal significant changes in the chemical species across the CDs: the formation of sulfonates and graphitic Nitrogen. Temperature-dependent measurements and normalized differential conductance analysis reveal that the ETp mechanism across the CDs behaves as tunneling, which is common to all CDs used here. The study shows that the conductivity of CDs is on par with that of sophisticated molecular wires, suggesting CDs as new 'green' candidates for molecular electronics applications.
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Affiliation(s)
- Yuval Toren
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, 32000, Israel
| | - Ayelet Vilan
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Nadav Amdursky
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, 32000, Israel
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9
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Papp E, Vattay G, Romero-Muñiz C, Zotti LA, Fereiro JA, Sheves M, Cahen D. Experimental Data Confirm Carrier-Cascade Model for Solid-State Conductance across Proteins. J Phys Chem B 2023; 127:1728-1734. [PMID: 36790863 DOI: 10.1021/acs.jpcb.2c07946] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
The finding that electronic conductance across ultrathin protein films between metallic electrodes remains nearly constant from room temperature to just a few degrees Kelvin has posed a challenge. We show that a model based on a generalized Landauer formula explains the nearly constant conductance and predicts an Arrhenius-like dependence for low temperatures. A critical aspect of the model is that the relevant activation energy for conductance is either the difference between the HOMO and HOMO-1 or the LUMO+1 and LUMO energies instead of the HOMO-LUMO gap of the proteins. Analysis of experimental data confirms the Arrhenius-like law and allows us to extract the activation energies. We then calculate the energy differences with advanced DFT methods for proteins used in the experiments. Our main result is that the experimental and theoretical activation energies for these three different proteins and three differently prepared solid-state junctions match nearly perfectly, implying the mechanism's validity.
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Affiliation(s)
- Eszter Papp
- Department of Physics of Complex Systems, Eötvös Loránd University, Egyetem tér 1-3., H-1053 Budapest, Hungary
| | - Gábor Vattay
- Department of Physics of Complex Systems, Eötvös Loránd University, Egyetem tér 1-3., H-1053 Budapest, Hungary
| | - Carlos Romero-Muñiz
- Departamento de Física Aplicada I, Universidad de Sevilla, E-41012 Seville, Spain
| | - Linda A Zotti
- Departamento de Física Teórica de la Materia Condensada and IFIMAC, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
| | - Jerry A Fereiro
- School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram - 695551 Kerala, India
| | - Mordechai Sheves
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, 76100 Rehovot, Israel
| | - David Cahen
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, 76100 Rehovot, Israel
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10
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Guo C, Gavrilov Y, Gupta S, Bendikov T, Levy Y, Vilan A, Pecht I, Sheves M, Cahen D. Electron transport via tyrosine-doped oligo-alanine peptide junctions: role of charges and hydrogen bonding. Phys Chem Chem Phys 2022; 24:28878-28885. [PMID: 36441625 DOI: 10.1039/d2cp02807g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A way of modulating the solid-state electron transport (ETp) properties of oligopeptide junctions is presented by charges and internal hydrogen bonding, which affect this process markedly. The ETp properties of a series of tyrosine (Tyr)-containing hexa-alanine peptides, self-assembled in monolayers and sandwiched between gold electrodes, are investigated in response to their protonation state. Inserting a Tyr residue into these peptides enhances the ETp carried via their junctions. Deprotonation of the Tyr-containing peptides causes a further increase of ETp efficiency that depends on this residue's position. Combined results of molecular dynamics simulations and spectroscopic experiments suggest that the increased conductance upon deprotonation is mainly a result of enhanced coupling between the charged C-terminus carboxylate group and the adjacent Au electrode. Moreover, intra-peptide hydrogen bonding of the Tyr hydroxyl to the C-terminus carboxylate reduces this coupling. Hence, the extent of such a conductance change depends on the Tyr-carboxylate distance in the peptide's sequence.
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Affiliation(s)
- Cunlan Guo
- Departments of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot, 761001, Israel. .,College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China
| | - Yulian Gavrilov
- Departments of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, 761001, Israel.,Division of Biophysical Chemistry, Center for Molecular Protein Science, Department of Chemistry, Lund University, SE-22100 Lund, Sweden
| | - Satyajit Gupta
- Departments of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot, 761001, Israel. .,Department of Chemistry, Indian Institute of Technology, Bhilai, 492015, India
| | - Tatyana Bendikov
- Department of Chemical Research Support, Weizmann Institute of Science, Rehovot, 761001, Israel
| | - Yaakov Levy
- Departments of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, 761001, Israel
| | - Ayelet Vilan
- Departments of Chemical & Biological Physics, Weizmann Institute of Science, Rehovot, 761001, Israel
| | - Israel Pecht
- Department of immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot, 761001, Israel
| | - Mordechai Sheves
- Departments of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot, 761001, Israel.
| | - David Cahen
- Departments of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot, 761001, Israel.
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11
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Li T, Hantusch M, Qu J, Bandari VK, Knupfer M, Zhu F, Schmidt OG. On-chip integrated process-programmable sub-10 nm thick molecular devices switching between photomultiplication and memristive behaviour. Nat Commun 2022; 13:2875. [PMID: 35610214 PMCID: PMC9130281 DOI: 10.1038/s41467-022-30498-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 05/05/2022] [Indexed: 11/24/2022] Open
Abstract
Molecular devices constructed by sub-10 nm thick molecular layers are promising candidates for a new generation of integratable nanoelectronic applications. Here, we report integrated molecular devices based on ultrathin copper phthalocyanine/fullerene hybrid layers with microtubular soft-contacts, which exhibit process-programmable functionality switching between photomultiplication and memristive behaviour. The local electric field at the interface between the polymer bottom electrode and the enclosed molecular channels modulates the ionic-electronic charge interaction and hence determines the transition of the device function. When ions are not driven into the molecular channels at a low interface electric field, photogenerated holes are trapped as electronic space charges, resulting in photomultiplication with a high external quantum efficiency. Once mobile ions are polarized and accumulated as ionic space charges in the molecular channels at a high interface electric field, the molecular devices show ferroelectric-like memristive switching with remarkable resistive ON/OFF and rectification ratios. Developing molecular electronics is challenged by integrating fragile organic molecules into modern micro/nanoelectronics based on inorganic semiconductors. Li et al. apply rolled-up nanotechnology to assemble on-chip molecular devices, which can be switched between photodiodes and volatile memristors.
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Affiliation(s)
- Tianming Li
- Center for Materials, Architectures and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, 09126, Chemnitz, Germany.,Material Systems for Nanoelectronics, Chemnitz University of Technology, 09107, Chemnitz, Germany.,Institute for Integrative Nanosciences, Leibniz IFW Dresden, 01069, Dresden, Germany
| | - Martin Hantusch
- Institute for Solid State Research, Leibniz IFW Dresden, 01069, Dresden, Germany
| | - Jiang Qu
- Center for Materials, Architectures and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, 09126, Chemnitz, Germany.,Material Systems for Nanoelectronics, Chemnitz University of Technology, 09107, Chemnitz, Germany.,Institute for Integrative Nanosciences, Leibniz IFW Dresden, 01069, Dresden, Germany
| | - Vineeth Kumar Bandari
- Center for Materials, Architectures and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, 09126, Chemnitz, Germany.,Material Systems for Nanoelectronics, Chemnitz University of Technology, 09107, Chemnitz, Germany.,Institute for Integrative Nanosciences, Leibniz IFW Dresden, 01069, Dresden, Germany
| | - Martin Knupfer
- Institute for Solid State Research, Leibniz IFW Dresden, 01069, Dresden, Germany
| | - Feng Zhu
- Center for Materials, Architectures and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, 09126, Chemnitz, Germany. .,Material Systems for Nanoelectronics, Chemnitz University of Technology, 09107, Chemnitz, Germany. .,Institute for Integrative Nanosciences, Leibniz IFW Dresden, 01069, Dresden, Germany. .,State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, 130022, Changchun, China.
| | - Oliver G Schmidt
- Center for Materials, Architectures and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, 09126, Chemnitz, Germany. .,Material Systems for Nanoelectronics, Chemnitz University of Technology, 09107, Chemnitz, Germany. .,Institute for Integrative Nanosciences, Leibniz IFW Dresden, 01069, Dresden, Germany. .,School of Science, Dresden University of Technology, 01069, Dresden, Germany.
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12
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Tang L, Yi L, Jiang T, Ren R, Paulose Nadappuram B, Zhang B, Wu J, Liu X, Lindsay S, Edel JB, Ivanov AP. Measuring conductance switching in single proteins using quantum tunneling. SCIENCE ADVANCES 2022; 8:eabm8149. [PMID: 35584212 PMCID: PMC9116604 DOI: 10.1126/sciadv.abm8149] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Interpreting the electrical signatures of single proteins in electronic junctions has facilitated a better understanding of the intrinsic properties of proteins that are fundamental to chemical and biological processes. Often, this information is not accessible using ensemble and even single-molecule approaches. In addition, the fabrication of nanoscale single-protein junctions remains challenging as they often require sophisticated methods. We report on the fabrication of tunneling probes, direct measurement, and active control (switching) of single-protein conductance with an external field in solution. The probes allowed us to bridge a single streptavidin molecule to two independently addressable, biotin-terminated electrodes and measure single-protein tunneling response over long periods. We show that charge transport through the protein has multiple conductive pathways that depend on the magnitude of the applied bias. These findings open the door for the reliable fabrication of protein-based junctions and can enable their use in future protein-embedded bioelectronics applications.
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Affiliation(s)
- Longhua Tang
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou 310027, China
- Innovation Institute for Artificial Intelligence in Medicine, Zhejiang-California International NanoSystems Institute, Zhejiang University, Hangzhou 310000, China
- Corresponding author. (L.T.); (A.P.I.); (J.B.E.)
| | - Long Yi
- Department of Chemistry, Molecular Science Research Hub, Imperial College London, White City Campus, 82 Wood Lane, London W12 0BZ, UK
| | - Tao Jiang
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou 310027, China
| | - Ren Ren
- Department of Chemistry, Molecular Science Research Hub, Imperial College London, White City Campus, 82 Wood Lane, London W12 0BZ, UK
| | - Binoy Paulose Nadappuram
- Department of Chemistry, Molecular Science Research Hub, Imperial College London, White City Campus, 82 Wood Lane, London W12 0BZ, UK
- Department of Pure and Applied Chemistry, University of Strathclyde, Technology and Innovation Centre, 99 George Street, Glasgow G1 1RD, UK
| | - Bintian Zhang
- Biodesign Institute; School of Life Sciences; Department of Physics; School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - Jian Wu
- Innovation Institute for Artificial Intelligence in Medicine, Zhejiang-California International NanoSystems Institute, Zhejiang University, Hangzhou 310000, China
| | - Xu Liu
- State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou 310027, China
| | - Stuart Lindsay
- Biodesign Institute; School of Life Sciences; Department of Physics; School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA
| | - Joshua B. Edel
- Department of Chemistry, Molecular Science Research Hub, Imperial College London, White City Campus, 82 Wood Lane, London W12 0BZ, UK
- Corresponding author. (L.T.); (A.P.I.); (J.B.E.)
| | - Aleksandar P. Ivanov
- Department of Chemistry, Molecular Science Research Hub, Imperial College London, White City Campus, 82 Wood Lane, London W12 0BZ, UK
- Corresponding author. (L.T.); (A.P.I.); (J.B.E.)
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13
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Zhang B, Ryan E, Wang X, Song W, Lindsay S. Electronic Transport in Molecular Wires of Precisely Controlled Length Built from Modular Proteins. ACS NANO 2022; 16:1671-1680. [PMID: 35029115 PMCID: PMC9279515 DOI: 10.1021/acsnano.1c10830] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
DNA molecular wires have been studied extensively because of the ease with which molecules of controlled length and composition can be synthesized. The same has not been true for proteins. Here, we have synthesized and studied a series of consensus tetratricopeptide repeat (CTPR) proteins, spanning 4 to 20 nm in length, in increments of 4 nm. For lengths in excess of 6 nm, their conductance exceeds that of the canonical molecular wire, oligo(phenylene-ethylenene), because of the more gradual decay of conductance with length in the protein. We show that, while the conductance decay fits an exponential (characteristic of quantum tunneling) and not a linear increase of resistance with length (characteristic of hopping transport), it is also accounted for by a square-law dependence on length (characteristic of weakly driven hopping). Measurements of the energy dependence of the decay length rule out the quantum tunneling case. A resonance in the carrier injection energy shows that allowed states in the protein align with the Fermi energy of the electrodes. Both the energy of these states and the long-range of hopping suggest that the reorganization induced by hole formation is greatly reduced inside the protein. We outline a model for calculating the molecular-electronic properties of proteins.
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Affiliation(s)
- Bintian Zhang
- Biodesign Institute, Arizona State University, Tempe, AZ 85281
| | - Eathen Ryan
- School of Molecular Sciences, Arizona State University, Tempe, AZ 85281
| | - Xu Wang
- School of Molecular Sciences, Arizona State University, Tempe, AZ 85281
| | - Weisi Song
- Biodesign Institute, Arizona State University, Tempe, AZ 85281
| | - Stuart Lindsay
- Biodesign Institute, Arizona State University, Tempe, AZ 85281
- School of Molecular Sciences, Arizona State University, Tempe, AZ 85281
- Department of Physics, Arizona State University, Tempe, AZ 85281
- Corresponding Author: Stuart Lindsay: Phone 480 205 6432
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14
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Cahen D, Pecht I, Sheves M. What Can We Learn from Protein-Based Electron Transport Junctions? J Phys Chem Lett 2021; 12:11598-11603. [PMID: 34852460 PMCID: PMC8647078 DOI: 10.1021/acs.jpclett.1c02446] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Affiliation(s)
- David Cahen
- Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Israel Pecht
- Weizmann Institute of Science, Rehovot 7610001, Israel
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15
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Engelbrekt C, Nazmutdinov RR, Shermukhamedov S, Ulstrup J, Zinkicheva TT, Xiao X. Complex single‐molecule and molecular scale entities in electrochemical environments: Mechanisms and challenges. ELECTROCHEMICAL SCIENCE ADVANCES 2021. [DOI: 10.1002/elsa.202100157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Christian Engelbrekt
- Department of Chemistry Technical University of Denmark Building 207, DK0‐2800 Kgs. Lyngby Denmark
| | - Renat R. Nazmutdinov
- Department of Inorganic Chemistry Kazan National Research Technological University Karl Marx Str. 68 Kazan 420015 Russian Federation
| | - Shokirbek Shermukhamedov
- Department of Inorganic Chemistry Kazan National Research Technological University Karl Marx Str. 68 Kazan 420015 Russian Federation
| | - Jens Ulstrup
- Department of Chemistry Technical University of Denmark Building 207, DK0‐2800 Kgs. Lyngby Denmark
| | - Tamara T. Zinkicheva
- Department of Inorganic Chemistry Kazan National Research Technological University Karl Marx Str. 68 Kazan 420015 Russian Federation
| | - Xinxin Xiao
- Department of Chemistry Technical University of Denmark Building 207, DK0‐2800 Kgs. Lyngby Denmark
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16
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Futera Z. Amino-acid interactions with the Au(111) surface: adsorption, band alignment, and interfacial electronic coupling. Phys Chem Chem Phys 2021; 23:10257-10266. [PMID: 33899874 DOI: 10.1039/d1cp00218j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The charge transport properties of biological molecules like peptides and proteins are intensively studied for the great flexibility, redox-state variability, long-range efficiency, and biocompatibility of potential bioelectronic applications. Yet, the electronic interactions of biomolecules with solid metal surfaces, determining the conductivities of the biomolecular junctions, are hard to predict and usually unavailable. Here, we present accurate adsorption structures and energies, electronic band alignment, and interfacial electronic coupling data for all 20 natural amino acids computed using the DFT+Σ scheme based on the vdW-DF and OT-RSH functionals. For comparison, data obtained using the popular PBE functional are provided as well. Tryptophan, compared to other amino acids, is shown to be distinctly exceptional in terms of the electronic properties related to charge transport. Its high adsorption energy, frontier-orbital levels aligned relatively close to the Fermi energy of gold and strong interfacial electronic coupling make it an ideal candidate for facilitating charge transfer on such heterogeneous interfaces. Although the amino acids in peptides and proteins are affected by the structural interactions hindering their contact with the surface, knowledge of the single-molecule surface interactions is necessary for a detailed understanding of such structural effects and tuning of potential applications.
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Affiliation(s)
- Zdenek Futera
- Faculty of Science, University of South Bohemia, Branisovska 1760, 370 05 Ceske Budejovice, Czech Republic.
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17
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Fereiro JA, Pecht I, Sheves M, Cahen D. Inelastic Electron Tunneling Spectroscopic Analysis of Bias-Induced Structural Changes in a Solid-State Protein Junction. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 17:e2008218. [PMID: 33783130 DOI: 10.1002/smll.202008218] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 02/10/2021] [Indexed: 05/25/2023]
Abstract
A central issue in protein electronics is how far the structural stability of the protein is preserved under the very high electrical field that it will experience once a bias voltage is applied. This question is studied on the redox protein Azurin in the solid-state Au/protein/Au junction by monitoring protein vibrations during current transport under applied bias, up to ≈1 GV m-1 , by electrical detection of inelastic electron transport effects. Characteristic vibrational modes, such as CH stretching, amide (NH) bending, and AuS (of the bonds that connect the protein to an Au electrode), are not found to change noticeably up to 1.0 V. At >1.0 V, the NH bending and CH stretching inelastic features have disappeared, while the AuS features persist till ≈2 V, i.e., the proteins remain Au bound. Three possible causes for the disappearance of the NH and CH inelastic features at high bias, namely, i) resonance transport, ii) metallic filament formation, and iii) bond rupture leading to structural changes in the protein are proposed and tested. The results support the last option and indicate that spectrally resolved inelastic features can serve to monitor in operando structural stability of biological macromolecules while they serve as electronic current conduit.
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Affiliation(s)
- Jerry A Fereiro
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Israel Pecht
- Department of Immunology, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Mordechai Sheves
- Department of Organic Chemistry, Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - David Cahen
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, 7610001, Israel
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18
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The Role of Metal Ions in the Electron Transport through Azurin-Based Junctions. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app11093732] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
We studied the coherent electron transport through metal–protein–metal junctions based on a blue copper azurin, in which the copper ion was replaced by three different metal ions (Co, Ni and Zn). Our results show that neither the protein structure nor the transmission at the Fermi level change significantly upon metal replacement. The discrepancy with previous experimental observations suggests that the transport mechanism taking place in these types of junctions is probably not fully coherent.
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19
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Gupta NK, Schultz T, Karuppannan SK, Vilan A, Koch N, Nijhuis CA. The energy level alignment of the ferrocene-EGaIn interface studied with photoelectron spectroscopy. Phys Chem Chem Phys 2021; 23:13458-13467. [PMID: 34095913 DOI: 10.1039/d1cp01690c] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The energy level alignment after the formation of a molecular tunnel junction is often poorly understood because spectroscopy inside junctions is not possible, which hampers the rational design of functional molecular junctions and complicates the interpretation of the data generated by molecular junctions. In molecular junction platforms where the top electrode-molecule interaction is weak; one may argue that the energy level alignment can be deduced from measurements with the molecules supported by the bottom electrode (sometimes referred to as "half junctions"). This approach, however, still relies on a series of assumptions, which are challenging to address experimentally due to difficulties in studying the molecule-top electrode interaction. Herein, we describe top electrode-molecule junctions with a liquid metal alloy top electrode of EGaIn (which stands for eutectic alloy of Ga and In) interacting with well-characterised ferrocene (Fc) moieties. We deposited a ferrocene derivative on films of EGaIn, coated with its native GaOx layer, and studied the energy level alignment with photoelectron spectroscopy. Our results reveal that the electronic interaction between the Fc and GaOx/EGaIn is very weak, resembling physisorption. Therefore, investigations of "half junctions" for this system can provide valuable information regarding the energy level alignment of complete EGaIn junctions. Our results help to improve our understanding of the energy landscape in weakly coupled molecular junctions and aid to the rational design of molecular electronic devices.
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Affiliation(s)
- Nipun Kumar Gupta
- Departement of Chemistry, Faculty of Science, National University of Singapore, Singapore, Singapore and Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore
| | - Thorsten Schultz
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstraße 15, 12489 Berlin, Germany. and Helmholtz Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein Straße 15, 12489 Berlin, Germany
| | - Senthil Kumar Karuppannan
- Departement of Chemistry, Faculty of Science, National University of Singapore, Singapore, Singapore
| | - Ayelet Vilan
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Norbert Koch
- Institut für Physik, Humboldt-Universität zu Berlin, Newtonstraße 15, 12489 Berlin, Germany. and Helmholtz Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein Straße 15, 12489 Berlin, Germany
| | - Christian A Nijhuis
- Departement of Chemistry, Faculty of Science, National University of Singapore, Singapore, Singapore and Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore and Department of Molecules and Materials, MESA+ Institute for Nanotechnology and Center for Brain-Inspired Nano Systems, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
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20
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Zhang L, Lu JR, Waigh TA. Electronics of peptide- and protein-based biomaterials. Adv Colloid Interface Sci 2021; 287:102319. [PMID: 33248339 DOI: 10.1016/j.cis.2020.102319] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 11/10/2020] [Accepted: 11/11/2020] [Indexed: 12/22/2022]
Abstract
Biologically inspired peptide- and protein-based materials are at the forefront of organic bioelectronics research due to their inherent conduction properties and excellent biocompatibility. Peptides have the advantages of structural simplicity and ease of synthesis providing credible prospects for mass production, whereas naturally expressed proteins offer inspiration with many examples of high performance evolutionary optimised bioelectronics properties. We review recent advances in the fundamental conduction mechanisms, experimental techniques and exemplar applications for the bioelectronics of self-assembling peptides and proteins. Diverse charge transfer processes, such as tunnelling, hopping and coupled transfer, are found in naturally occurring biological systems with peptides and proteins as the predominant building blocks to enable conduction in biology. Both theory and experiments allow detailed investigation of bioelectronic properties in order to design functionalized peptide- and protein-based biomaterials, e.g. to create biocompatible aqueous electrodes. We also highlight the design of bioelectronics devices based on peptides/proteins including field-effect transistors, piezoelectric energy harvesters and optoelectronics.
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Affiliation(s)
- L Zhang
- Biological Physics, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - J R Lu
- Biological Physics, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
| | - T A Waigh
- Biological Physics, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK; Photon Science Institute, Department of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, UK.
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21
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Fereiro JA, Bendikov T, Pecht I, Sheves M, Cahen D. Protein Binding and Orientation Matter: Bias-Induced Conductance Switching in a Mutated Azurin Junction. J Am Chem Soc 2020; 142:19217-19225. [PMID: 33141577 PMCID: PMC7662909 DOI: 10.1021/jacs.0c08836] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Indexed: 02/07/2023]
Abstract
We observe reversible, bias-induced switching of conductance via a blue copper protein azurin mutant, N42C Az, with a nearly 10-fold increase at |V| > 0.8 V than at lower bias. No such switching is found for wild-type azurin, WT Az, up to |1.2 V|, beyond which irreversible changes occur. The N42C Az mutant will, when positioned between electrodes in a solid-state Au-protein-Au junction, have an orientation opposite that of WT Az with respect to the electrodes. Current(s) via both proteins are temperature-independent, consistent with quantum mechanical tunneling as dominant transport mechanism. No noticeable difference is resolved between the two proteins in conductance and inelastic electron tunneling spectra at <|0.5 V| bias voltages. Switching behavior persists from 15 K up to room temperature. The conductance peak is consistent with the system switching in and out of resonance with the changing bias. With further input from UV photoemission measurements on Au-protein systems, these striking differences in conductance are rationalized by having the location of the Cu(II) coordination sphere in the N42C Az mutant, proximal to the (larger) substrate-electrode, to which the protein is chemically bound, while for the WT Az that coordination sphere is closest to the other Au electrode, with which only physical contact is made. Our results establish the key roles that a protein's orientation and binding nature to the electrodes play in determining the electron transport tunnel barrier.
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Affiliation(s)
- Jerry A. Fereiro
- Department
of Materials and Interfaces, Weizmann Institute
of Science, Rehovot 76100, Israel
| | - Tatyana Bendikov
- Department
of Chemical Research Support, Weizmann Institute
of Science, Rehovot 76100, Israel
| | - Israel Pecht
- Department
of Immunology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Mordechai Sheves
- Department
of Organic Chemistry, Weizmann Institute
of Science, Rehovot 76100, Israel
| | - David Cahen
- Department
of Materials and Interfaces, Weizmann Institute
of Science, Rehovot 76100, Israel
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22
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Zhang B, Song W, Brown J, Nemanich R, Lindsay S. Electronic Conductance Resonance in Non-Redox-Active Proteins. J Am Chem Soc 2020; 142:6432-6438. [PMID: 32176496 DOI: 10.1021/jacs.0c01805] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Bioelectronics research has mainly focused on redox-active proteins because of their role in biological charge transport. In these proteins, electronic conductance is a maximum when electrons are injected at the known redox potential of the protein. It has been shown recently that many non-redox-active proteins are good electronic conductors, though the mechanism of conduction is not yet understood. Here, we report single-molecule measurements of the conductance of three non-redox-active proteins, maintained under potential control in solution, as a function of electron injection energy. All three proteins show a conductance resonance at a potential ∼0.7 V removed from the nearest oxidation potential of their constituent amino acids. If this shift reflects a reduction of reorganization energy in the interior of the protein, it would account for the long-range conductance observed when carriers are injected into the interior of a protein.
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Affiliation(s)
- Bintian Zhang
- Biodesign Institute, Arizona State University, Tempe, Arizona 87287, United States
| | - Weisi Song
- Biodesign Institute, Arizona State University, Tempe, Arizona 87287, United States
| | - Jesse Brown
- Department of Physics, Arizona State University, Tempe, Arizona 87287, United States
| | - Robert Nemanich
- Department of Physics, Arizona State University, Tempe, Arizona 87287, United States
| | - Stuart Lindsay
- Biodesign Institute, Arizona State University, Tempe, Arizona 87287, United States.,Department of Physics, Arizona State University, Tempe, Arizona 87287, United States.,School of Molecular Sciences, Arizona State University, Tempe, Arizona 87287, United States
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