Electrochemical Detection of Single Molecules

Fan, Fu Ren F.; Bard, Allen J.

doi:10.1126/science.267.5199.871

Cited by 397 publications

(344 citation statements)

References 12 publications

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“…This is well known in SECM (scanning electrochemical microscopy) and used as a mechanism to control the distance between SECM probe and substrate surface 29 . At very small electrode distances, this can result in measurable steady-state currents, involving a few or even a single molecule(s) 30,31 . Such redox cycling may easily be mistaken for (redox-mediated) hopping transport and one expects that for sufficiently small electrode distances, the charge transport across an electrode/molecule/electrode junction is illustrated in the adjacent figure: the two electrodes 1 and 2 have Fermi levels µ 1,2 , which differ by − eV b .…”

Section: Tunnelling Transport In Liquid-filled Electrode Junctionsmentioning

confidence: 99%

Electrochemical tunnelling sensors and their potential applications

Albrecht

2012

Nat Commun

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the quantum-mechanical tunnelling effect allows charge transport across nanometre-scale gaps between conducting electrodes. application of a voltage between these electrodes leads to a measurable tunnelling current, which is highly sensitive to the gap size, the voltage applied and the medium in the gap. applied to liquid environments, this offers interesting prospects of using tunnelling currents as a sensitive tool to study fundamental interfacial processes, to probe chemical reactions at the single-molecule level and to analyse the composition of biopolymers such as Dna, rna or proteins. this offers the possibility of a new class of sensor devices with unique capabilities. E lectrochemical sensors based on measuring the tunnelling current across nanoscale electrode junctions in solution are emerging as a new class of single-molecule sensors. They combine extremely high spatial resolution with sensitivity to the electronic structure of the analyte. This opens up perspectives towards the label-free detection of small molecules, the characterization of catalytic or enzymatic processes at the single-molecule level as well as the analysis of biopolymers with sub-molecular resolution, Fig. 1. To this end, label-free, fast and inexpensive RNA and DNA sequencing may be in reach, potentially revolutionizing the way we perform gene sequencing today.Charge transfer by quantum-mechanical tunnelling is one of the most ubiquitous elementary processes in nature and features in areas as diverse as electron or hydrogen transfer in enzymatic reactions, interfacial charge transfer at metal electrodes in solution, thin-layer devices in electronics, charge transfer between crystal defects and radioactive α-decay 1 . Important applications exploiting tunnelling transport include the Esaki tunnelling diode and the scanning tunnelling microscope (STM)-both recognized with the Nobel Prize in Physics for their inventors, namely Esaki in 1973 (jointly with Josephson), and Binnig and Rohrer in 1986, respectively.'Tunnelling' refers to the transport of electrons (or other light charge carriers) across a nanometre-sized gap, a molecule or even an insulating layer between two electrodes. Upon application of a bias voltage V bias between the two electrodes, negatively charged electrons are more likely to be transported towards the positively biased electrode and a so-called 'tunnelling current' I t is detected. The latter depends exponentially on gap size, which is the reason for the high spatial resolution of STM, the applied voltage V b and the electronic structure of the medium in the gap. To this end, the electrode junction may be represented by a transmission function that characterizes the probability of electrons moving from one electrode across the gap into the second electrode, summarized over all energy levels.Hence, the more accessible the energy levels in the junction, and the better their electronic coupling to the electrodes, the higher current across the junction. This also implies that the tunnelling current is sensitive to ...

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Section: Tunnelling Transport In Liquid-filled Electrode Junctionsmentioning

confidence: 99%

Electrochemical tunnelling sensors and their potential applications

Albrecht

2012

Nat Commun

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“…A large current per molecule corresponds to efficient redox cycling and is achieved with small roof heights. In the limit h→50 nm, the device resembles a TLC, and the current per molecule is simply neD z 2 ¼ 1:2 fA for n ¼ 2 and z ¼ 250 nm ð Þ , where e is the charge of one electron [18,40]. Controlling the height of the roof, h, therefore allows tuning between regimes of efficient cycling and high selectivity (h→50 nm) and maximum signal level (h→∞).…”

Section: Theorymentioning

confidence: 99%

“…The extension of amperometric detection methods to the nanoscale has already yielded much new information about mass transfer [10][11][12], adsorption [13,14], and electron-transfer kinetics [15][16][17] that would be otherwise difficult to observe. One goal of nanofluidics, the handling and probing of individual molecules, is already becoming a reality [16,18]. As a further example, miniature probes are increasingly employed for in vivo measurements of neurotransmitters in the brain [19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Redox cycling in nanofluidic channels using interdigitated electrodes

et al. 2009

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Amperometric detection is ideally suited for integration into micro-and nanofluidic systems as it directly yields an electrical signal and does not necessitate optical components. However, the range of systems to which it can be applied is constrained by the limited sensitivity and specificity of the method. These limitations can be partially alleviated through the use of redox cycling, in which multiple electrodes are employed to repeatedly reduce and oxidize analyte molecules and thereby amplify the detected signal. We have developed an interdigitated electrode device that is encased in a nanofluidic channel to provide a hundred-fold amplification of the amperometric signal from paracetamol. Due to the nanochannel design, the sensor is resistant to interference from molecules undergoing irreversible redox reactions. We demonstrate this selectivity by detecting paracetamol in the presence of excess ascorbic acid.

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“…While this conceptual difference appears to be clear, particular experiments trigger intensive debates [68][69][70][71][72][73]. The general similarity of the instrumentation provoked some "jargon" in SECM.…”

Section: Secm Instrumentation and Basic Concepts 21 Instrumentationmentioning

confidence: 99%

Investigation of Localized Catalytic and Electrocatalytic Processes and Corrosion Reactions with Scanning Electrochemical Microscopy (SECM)

Pust¹,

Maier²,

Wittstock³

2008

Zeitschrift Für Physikalische Chemie

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Scanning Electrochemical Microscopy (SECM) . Catalytic Electrodes .Electrochemical Energy Conversion . Fuel Cells . Oxygen Reduction Reaction . CorrosionScanning electrochemical microscopy (SECM) has developed into a very versatile tool for the investigation of solid-liquid, liquid-liquid and liquid-gas interfaces. The arrangement of an ultramicroelectrode (UME) in close proximity to the interface under study allows the application of a large variety of different experimental schemes. The most important have been named feedback mode, generation-collection mode, redox competition mode and direct mode. Quantitative descriptions are available for the UME signal, depending on different sample properties and experimental variables. Therefore, SECM has been established as an indispensible tool in many areas of fundamental electrochemical research. Currently, it also spreads as an important new method to solve more applied problems, in which inhomogeneous current distributions are typically observed on different length scales. Prominent examples include devices for electrochemical energy conversion such as fuel cells and batteries as well as localized corrosion phenomena. However, the direct local investigation of such systems is often impossible. Instead, suitable reaction schemes, sample environments, model samples and even new operation modes have to be introduced in order to obtain results that are relevant to the practical application. This review outlines and compares the theoretical basis of the different SECM working modes and reviews the application in the area of electrochemical energy conversion and localized

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Electrochemical Detection of Single Molecules

Cited by 397 publications

References 12 publications

Electrochemical tunnelling sensors and their potential applications

Electrochemical tunnelling sensors and their potential applications

Redox cycling in nanofluidic channels using interdigitated electrodes

Investigation of Localized Catalytic and Electrocatalytic Processes and Corrosion Reactions with Scanning Electrochemical Microscopy (SECM)

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