Browse
Submit Data
Databases
API
Help

Dataset Information

13 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Probe-based measurement of lateral single-electron transfer between individual molecules.

ABSTRACT: The field of molecular electronics aims at using single molecules as functional building blocks for electronics components, such as switches, rectifiers or transistors. A key challenge is to perform measurements with atomistic control over the alignment of the molecule and its contacting electrodes. Here we use atomic force microscopy to examine charge transfer between weakly coupled pentacene molecules on insulating films with single-electron sensitivity and control over the atomistic details. We show that, in addition to the imaging capability, the probe tip can be used to control the charge state of individual molecules and to detect charge transfers to/from the tip, as well as between individual molecules. Our approach represents a novel route for molecular charge transfer studies with a host of opportunities, especially in combination with single atom/molecule manipulation and nanopatterning techniques.

SUBMITTER: Steurer W

PROVIDER: S-EPMC4595756 | biostudies-literature | 2015 Sep

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Probe-based measurement of lateral single-electron transfer between individual molecules.

Steurer Wolfram W Fatayer Shadi S Gross Leo L Meyer Gerhard G

Nature communications 20150921

The field of molecular electronics aims at using single molecules as functional building blocks for electronics components, such as switches, rectifiers or transistors. A key challenge is to perform measurements with atomistic control over the alignment of the molecule and its contacting electrodes. Here we use atomic force microscopy to examine charge transfer between weakly coupled pentacene molecules on insulating films with single-electron sensitivity and control over the atomistic details. ...[more]

PMID: 26387533

Similar Datasets

Probing conformational dynamics in single donor-acceptor synthetic molecules by means of photoinduced reversible electron transfer.

Project description:We use single-molecule fluorescence lifetimes to probe dynamics of photoinduced reversible electron transfer occurring between triphenylamine (donor) and perylenediimide (acceptor) in single molecules of a polyphenylenic rigid dendrimer embedded in polystyrene. Here, reversible electron transfer in individual donor-acceptor molecules results in delayed fluorescence that is emitted with a high photon count rate. By monitoring fluorescence decay times on a photon-by-photon basis, we find fluctuations in both forward and reverse electron transfer spanning a broad time range, from milliseconds to seconds. Fluctuations are induced by conformational changes in the dendrimer structure as well by polystyrene chain reorientation. The conformational changes are related to changes in the dihedral angle of adjacent phenyl rings located in the dendritic branch near the donor transferring the charge, a torsional motion that results in millisecond fluctuations in the "through-bond" donor-acceptor electronic coupling. Polymer chain reorientation leads to changes in the local polarity experienced by the donors and to changes in the solvation of the charge-separated state. As a result, switching between different donor moieties within the same single molecule becomes possible and induces fluctuations in decay time on a time scale of seconds.

| S-EPMC521947 | biostudies-literature

DEER distance measurement between a spin label and a native FAD semiquinone in electron transfer flavoprotein.

Project description:The human mitochondrial electron transfer flavoprotein (ETF) accepts electrons from at least 10 different flavoprotein dehydrogenases and transfers electrons to a single electron acceptor in the inner membrane. Paracoccus denitrificans ETF has the identical function, shares the same three-dimensional structure and functional domains, and exhibits the same conformational mobility. It has been proposed that the mobility of the alphaII domain permits the promiscuous behavior of ETF with respect to a variety of redox partners. Double electron-electron resonance (DEER) measurements between a spin label and an enzymatically reduced flavin adenine dinucleotide (FAD) cofactor in P. denitrificans ETF gave two distributions of distances: a major component centered at 4.2 +/- 0.1 nm and a minor component centered at 5.1 +/- 0.2 nm. Both components had widths of approximately 0.3 nm. A distance of 4.1 nm was calculated using the crystal structure of P. denitrificans ETF, which agrees with the major component obtained from the DEER measurement. The observation of a second distribution suggests that ETF, in the absence of substrate, adopts some conformations that are intermediate between the predominant free and substrate-bound states.

| S-EPMC2782885 | biostudies-literature

Voltage-induced long-range coherent electron transfer through organic molecules.

Project description:Biological structures rely on kinetically tuned charge transfer reactions for energy conversion, biocatalysis, and signaling as well as for oxidative damage repair. Unlike man-made electrical circuitry, which uses metals and semiconductors to direct current flow, charge transfer in living systems proceeds via biomolecules that are nominally insulating. Long-distance charge transport, which is observed routinely in nucleic acids, peptides, and proteins, is believed to arise from a sequence of thermally activated hopping steps. However, a growing number of experiments find limited temperature dependence for electron transfer over tens of nanometers. To account for these observations, we propose a temperature-independent mechanism based on the electric potential difference that builds up along the molecule as a precursor of electron transfer. Specifically, the voltage changes the nature of the electronic states away from being sharply localized so that efficient resonant tunneling across long distances becomes possible without thermal assistance. This mechanism is general and is expected to be operative in molecules where the electronic states densely fill a wide energy window (on the scale of electronvolts) above or below the gap between the highest-occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). We show that this effect can explain the temperature-independent charge transport through DNA and the strongly voltage-dependent currents that are measured through organic semiconductors and peptides.

| S-EPMC6442562 | biostudies-literature

Transition from stochastic events to deterministic ensemble average in electron transfer reactions revealed by single-molecule conductance measurement.

Project description:Electron transfer reactions can now be followed at the single-molecule level, but the connection between the microscopic and macroscopic data remains to be understood. By monitoring the conductance of a single molecule, we show that the individual electron transfer reaction events are stochastic and manifested as large conductance fluctuations. The fluctuation probability follows first-order kinetics with potential dependent rate constants described by the Butler-Volmer relation. Ensemble averaging of many individual reaction events leads to a deterministic dependence of the conductance on the external electrochemical potential that follows the Nernst equation. This study discloses a systematic transition from stochastic kinetics of individual reaction events to deterministic thermodynamics of ensemble averages and provides insights into electron transfer processes of small systems, consisting of a single molecule or a small number of molecules.

| S-EPMC6397580 | biostudies-literature

Site-selective photo crosslink to methyllysine readers via single electron transfer between sulfonium and tryptophan

Project description:Reader proteins play significant roles in cell signaling from site-specific lysine methylation, but the progress of new reader investigations is rather slow. Photoreactive crosslinkers enable reader identifications, but it requires laborious chemical synthesis for optimization of the photoreactive group placement. In addition, active intermediate such as nitrene and carbene may cause significant non-specific crosslinking. Here we report dimethylsulfonium as methyllysine mimic binds to specific readers and subsequently crosslinks to conserved tryptophan inside binding pocket via single electron transfer under UV irradiation. Because the σ-π electron-donor-acceptor interaction between sulfonium and indole is a key step, the crosslinking exhibits excellent tryptophan site-selectivity and orthogonality to distinct methyllysine readers. Moreover, excited tryptophan without proximate sulfonium leads to minimal non-specific crosslinking from relaxation. Consequently, this method could escalate discovery of methyllysine readers from complicated cell samples. Furthermore, this photo crosslinking concept could be expanded to develop more types of microenvironment-dependent conjugations to site-specific tryptophan.

2024-02-04 | PXD049149 | iProX

Electrophoretic Deformation of Individual Transfer RNA Molecules Reveals Their Identity.

Project description:It has been hypothesized that the ribosome gains additional fidelity during protein translation by probing structural differences in tRNA species. We measure the translocation kinetics of different tRNA species through ?3 nm diameter synthetic nanopores. Each tRNA species varies in the time scale with which it is deformed from equilibrium, as in the translocation step of protein translation. Using machine-learning algorithms, we can differentiate among five tRNA species, analyze the ratios of tRNA binary mixtures, and distinguish tRNA isoacceptors.

| S-EPMC4890568 | biostudies-literature

Electron transfer between colloidal ZnO nanocrystals.

Project description:Colloidal ZnO nanocrystals capped with dodecylamine and dissolved in toluene can be charged photochemically to give stable solutions in which electrons are present in the conduction bands of the nanocrystals. These conduction-band electrons are readily monitored by EPR spectroscopy, with g* values that correlate with the nanocrystal sizes. Mixing a solution of charged small nanocrystals (e(-)(CB):ZnO-S) with a solution of uncharged large nanocrystals (ZnO-L) caused changes in the EPR spectrum indicative of quantitative electron transfer from small to large nanocrystals. EPR spectra of the reverse reaction, e(-)(CB):ZnO-L + ZnO-S, showed that electrons do not transfer from large to small nanocrystals. Stopped-flow kinetics studies monitoring the change in the UV band-edge absorption showed that reactions of 50 ?M nanocrystals were complete within the 5 ms mixing time of the instrument. Similar results were obtained for the reaction of charged nanocrystals with methyl viologen (MV(2+)). These and related results indicate that the electron-transfer reactions of these colloidal nanocrystals are quantitative and very rapid, despite the presence of ~1.5 nm long dodecylamine capping ligands. These soluble ZnO nanocrystals are thus well-defined redox reagents suitable for studies of electron transfer involving semiconductor nanostructures.

| S-EPMC3073092 | biostudies-literature

Enhanced enzyme activity through electron transfer between single-walled carbon nanotubes and horseradish peroxidase.

Project description:Better understanding of electron transfer (ET) taking place at the nano-bio interface can guide design of more effective functional materials used in fuel cells, biosensors, and medical devices. Single-walled carbon nanotube (SWCNT) coupled with biological enzymes serves as a model system for studying the ET mechanism, as demonstrated in the present study. SWCNT enhanced the activity of horseradish peroxidase (HRP) in the solution-based redox reaction by binding to HRP at a site proximate to the enzyme's activity center and participating in the ET process. ET to and from SWCNT was clearly observable using near-infrared spectroscopy. The capability of SWCNT in receiving electrons and the direct attachment of HRP to the surface of SWCNT strongly affected the enzyme activity due to the direct involvement of SWCNT in ET.

| S-EPMC3249833 | biostudies-literature

Single electron transfer between sulfonium and tryptophan enables site-selective photo crosslinking of methyllysine reader proteins

Project description:Reader proteins play significant roles in cell signaling from site-specific lysine methylation, but progress of new reader investigations is rather slow. Photoreactive crosslinkers enable the discovery of reader proteins, but the chemical synthesis required to optimize the placement of the photoreactive group is laborious. In addition, active intermediates such as nitrene and carbene may cause significant non-specific crosslinking. Here we report dimethylsulfonium as a methyllysine mimic that binds to specific readers and can subsequently crosslink to a conserved tryptophan inside the binding pocket through single electron transfer under UV irradiation. The crosslinking requires σ-π electron-donor-acceptor interaction between sulfonium and indole as a key step, facilitating excellent tryptophan site-selectivity and orthogonality to distinct methyllysine readers. Moreover, excited tryptophan without proximate sulfonium leads to minimal non-specific crosslinking from relaxation. This method could escalate the discovery of methyllysine readers from complex cell samples. Furthermore, this photo crosslinking concept could also be expanded to develop more types of microenvironment-dependent conjugations to site-specific tryptophan.

2024-06-30 | PXD051693 | Pride

Fluorescence spectroscopic detection and measurement of single telomere molecules.

Project description:Telomeres are the end-caps of chromosomes that serve to protect the integrity of the genome. Below certain critical lengths, the telomeres can no longer fulfill their protective function, and chromosomal instability ensues. Telomeres shorten during normal cell division due to the end replication problem and are implicated in the development of various aging-associated diseases, including cancer. Telomere length has the potential to serve as a useful biomarker in the field of aging and cancer. However, existing methods of telomere measurement are either too laborious, unable to provide absolute measurement of individual telomere lengths, or limited to certain chromosomes or cell types. Here, we describe an easy single-molecule, fluorescence spectroscopic method for measuring the length of telomeres that permits the profiling of absolute telomere lengths in any DNA sample. We have demonstrated the accurate detection of telomeres as short as 100 bp using cloned telomere standards, and have profiled telomere lengths in human cancer cell lines and primary cells. Since this method allows direct comparison between samples, it could greatly improve the clinical utility of telomere biomarkers.

| S-EPMC6212783 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data