Graphite: A Mimic for DNA and Other Biomolecules in Scanning Tunneling Microscope Studies

Clemmer, Carol R.; Beebe, Thomas P.

doi:10.1126/science.1992517

Cited by 296 publications

(140 citation statements)

References 18 publications

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“…This is consistent with the structure of topological defects in polycrystalline monolayer graphene discussed below. Later, the interest in GB defects in graphene was renewed with the advent of scanning tunnelling microscopy (STM) for investigating surfaces [27][28][29][30] . Scanning tunnelling spectroscopy (STS) allowed the local electronic properties of these defects in graphite to be investigated in detail 31 .…”

Section: Structure Of Polycrystalline Graphenementioning

confidence: 99%

Polycrystalline graphene and other two-dimensional materials

2014

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Graphene, a single atomic layer of graphitic carbon, has attracted intense attention due to its extraordinary properties that make it a suitable material for a wide range of technological applications. Large-area graphene films, which are necessary for industrial applications, are typically polycrystalline, that is, composed of single-crystalline grains of varying orientation joined by grain boundaries. Here, we present a review of the large body of research reported in the past few years on polycrystalline graphene. We discuss its growth and formation, the microscopic structure of grain boundaries and their relations to other types of topological defects such as dislocations. The review further covers electronic transport, optical and mechanical properties pertaining to the characterizations of grain boundaries, and applications of polycrystalline graphene. We also discuss research, still in its infancy, performed on other 2D materials such as transition metal dichalcogenides, and offer perspectives for future directions of research.Comment: review article; part of focus issue "Graphene applications

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Section: Structure Of Polycrystalline Graphenementioning

confidence: 99%

Polycrystalline graphene and other two-dimensional materials

2014

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“…However, whereas several groups showed high-resolution images with quite detailed structure of the DNA molecules [11][12][13][14][15][16][17][18] , direct tunnelling spectroscopy across the helices was reported only a few times [18][19][20][21] and clear interpretation was inhibited by technical hurdles 22 . In all of these studies, DNA-salt aggregates or very short DNA oligomers with no clear orientation were measured.…”

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confidence: 99%

Electronic structure of single DNA molecules resolved by transverse scanning tunnelling spectroscopy

Shapir

Cohen

Calzolari³

et al. 2007

Nature Mater

147

176

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Attempts to resolve the energy-level structure of single DNA molecules by scanning tunnelling spectroscopy span over the past two decades, owing to the unique ability of this technique to probe the local density of states of objects deposited on a surface. Nevertheless, success was hindered by extreme technical difficulties in stable deposition and reproducibility. Here, by using scanning tunnelling spectroscopy at cryogenic temperature, we disclose the energy spectrum of poly(G)-poly(C) DNA molecules deposited on gold. The tunnelling current-voltage (I-V ) characteristics and their derivative (dI/dV -V ) curves at 78 K exhibit a clear gap and a peak structure around the gap. Limited fluctuations in the I-V curves are observed and statistically characterized. By means of ab initio density functional theory calculations, the character of the observed peaks is generally assigned to groups of orbitals originating from the different molecular components, namely the nucleobases, the backbone and the counterions.The electrical properties of single double-stranded DNA molecules have attracted great interest in the past two decades, leading to a series of experiments 1-3 to study the electron transfer and conduction through single DNA molecules and in various aggregation forms 4,5 . Nearly all of the single-molecule experiments addressed the conductivity along molecules that are attached to electrodes at the molecule ends. Besides fixing many chemical and physical properties, the intrinsic electronic structure of an object also determines its response to an external electric field. Hence, it is desirable to get this knowledge for DNA to understand its suitability to support electrical currents and the viable transport mechanisms. Scanning tunnelling spectroscopy (STS) is the technique of choice for measuring the electronic density of states (DOS) of a single molecule 6 , as was demonstrated through the years for various carbon nanostructures 7,8 , molecular objects 9 and inorganic nanoparticles 10 deposited on substrates.Following the invention of the scanning tunnelling microscope (STM) in 1982, there was a substantial number of attempts to measure single DNA molecules using STM. However, whereas several groups showed high-resolution images with quite detailed structure of the DNA molecules [11][12][13][14][15][16][17][18] , direct tunnelling spectroscopy across the helices was reported only a few times 18-21 and clear interpretation was inhibited by technical hurdles 22 . In all of these studies, DNA-salt aggregates or very short DNA oligomers with no clear orientation were measured. Moreover, the STS measurements of DNA were always done at room temperature, making it impossible to resolve the electronic levels within the thermal noise.Theoretical predictions for the DNA electronic structure, commonly based on molecular quantum mechanics calculations such as density functional theory 23,24 (DFT) or Hartree-Fock 25 , cannot be conclusive. In fact, the lack of clear experimental data for single DNA molecules hinders the...

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“…We then imaged the uncoated immunoglobulin G deposited on highly oriented pyrolytic graphite (HOPG). Depending on the concentrations of IgG used and on the imaging conditions we observed either flat areas of apparently bare graphite with occasional steps and images similar to those described by Clemmer and Beebe [20], or large aggregates without apparent structure that changed from scan to scan. In several occasions, however, we imaged objects like the one shown in figure 3, panel A, clearly composed of two similar structures (80 x 40 À) resembling the Fab fragments of an IgG associated with a lower part whose sides measure 60 À interpreted as the Fc fragment.…”

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confidence: 70%