Nanocavity Redox Cycling Sensors for the Detection of Dopamine Fluctuations in Microfluidic Gradients

Kätelhön, Enno; Hofmann, Boris; Lemay, Serge G.; Zevenbergen, Marcel A. G.; Offenhäusser, Andreas; Wolfrum, Bernhard

doi:10.1021/ac101387f

Cited by 72 publications

(38 citation statements)

References 33 publications

(44 reference statements)

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“…The redox systems selected for this study are the two-electron reduction of anthraquinone and the two-electron oxidation of dopamine 20 to reflect possible problems of interferences during reduction (oxygen) and interferences during oxidation (ascorbate). Both of these systems have been studied for a considerable time.…”

Section: Figurementioning

confidence: 99%

A dual-plate ITO–ITO generator–collector microtrench sensor: surface activation, spatial separation and suppression of irreversible oxygen and ascorbate interference

Hasnat

Gross

Dale

et al. 2014

Analyst

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Generator-collector electrode systems are based on two independent working electrodes with overlapping diffusion fields where chemically reversible redox processes (oxidation and reduction) are coupled to give amplified current signals. A generator-collector trench electrode system prepared from two tin-doped indium oxide (ITO) electrodes placed vis-à-vis with a 22 μm inter-electrode gap is employed here as a sensor in aqueous media. The reversible 2-electron anthraquinone-2-sulfonate redox system is demonstrated to give well-defined collector responses even in the presence of oxygen due to the irreversible nature of the oxygen reduction. For the oxidation of dopamine on ITO, novel "Piranha-activation" effects are observed and chemically reversible generator-collector feedback conditions are achieved at pH 7, by selecting a more negative collector potential, again eliminating possible oxygen interference. Finally, dopamine oxidation in the presence of ascorbate is demonstrated with the irreversible oxidation of ascorbate at the "mouth" of the trench electrode and chemically reversible oxidation of dopamine in the trench "interior". This spatial separation of chemically reversible and irreversible processes within and outside the trench is discussed as a potential in situ microscale sensing and separation tool.

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Section: Figurementioning

confidence: 99%

A dual-plate ITO–ITO generator–collector microtrench sensor: surface activation, spatial separation and suppression of irreversible oxygen and ascorbate interference

Hasnat

Gross

Dale

et al. 2014

Analyst

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“…Particularly, one may expect that the detection or mapping of neutrotransmitter secretion (such as the redox-active molecule dopamine [13]) in neuronal networks will be one of the most interesting applications [27–37]. In this case, the sensor array is exposed to fast fluctuations in the neurotransmitter concentration.…”

Section: Resultsmentioning

confidence: 99%

“…The current per molecule obtained with such a sensor featuring the inter electrode distance h is directly proportional to h −2 . Therefore, small inter-electrode distances can significantly amplify the electrochemical signal [12–13]. Amplification factors can be calculated via comparison to a single electrode of the same size and may reach several orders of magnitudes, allowing very low detection limits; Recently, Lemay’s group reported the ultimate detection limit by sensing at molecular resolution inside a nanofluidic redox cycling device [14–16].…”

Section: Introductionmentioning

confidence: 99%

Nanocavity crossbar arrays for parallel electrochemical sensing on a chip

Kätelhön¹,

Mayer²,

Banzet³

et al. 2014

Beilstein J. Nanotechnol.

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SummaryWe introduce a novel device for the mapping of redox-active compounds at high spatial resolution based on a crossbar electrode architecture. The sensor array is formed by two sets of 16 parallel band electrodes that are arranged perpendicular to each other on the wafer surface. At each intersection, the crossing bars are separated by a ca. 65 nm high nanocavity, which is stabilized by the surrounding passivation layer. During operation, perpendicular bar electrodes are biased to potentials above and below the redox potential of species under investigation, thus, enabling repeated subsequent reactions at the two electrodes. By this means, a redox cycling current is formed across the gap that can be measured externally. As the nanocavity devices feature a very high current amplification in redox cycling mode, individual sensing spots can be addressed in parallel, enabling high-throughput electrochemical imaging. This paper introduces the design of the device, discusses the fabrication process and demonstrates its capabilities in sequential and parallel data acquisition mode by using a hexacyanoferrate probe.

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“…10 β (b)] to direct target biomarkers towards the sensor surface [(Fig. 10 β (c)] for improving sensitivity.” Another emerging trend consists in signal amplification through redox cycling within nanocavities due to near-instantaneous diffusion across the points of generation and collection of redox species within a nanofluidic device [ 182 , 183 ]. On a related note, electrochemical detection within micro/nanofluidic systems will also enable high-sensitivity measurement within small sample volumes for detection, which is especially relevant for measurements at high spatial and temporal resolution, using droplets collected by microdialysis [ 184 – 186 ].…”

Section: Future Challenges and Outlookmentioning

confidence: 99%

Nanomaterial-based electrochemical sensing of neurological drugs and neurotransmitters

et al. 2014

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Nanomaterial-modified detection systems represent a chief driver towards the adoption of electrochemical methods, since nanomaterials enable functional tunability, ability to self-assemble, and novel electrical, optical and catalytic properties that emerge at this scale. This results in tremendous gains in terms of sensitivity, selectivity and versatility. We review the electrochemical methods and mechanisms that may be applied to the detection of neurological drugs. We focus on understanding how specific nano-sized modifiers may be applied to influence the electron transfer event to result in gains in sensitivity, selectivity and versatility of the detection system. This critical review is structured on the basis of the Anatomical Therapeutic Chemical (ATC) Classification System, specifically ATC Code N (neurotransmitters). Specific sections are dedicated to the widely used electrodes based on the carbon materials, supporting electrolytes, and on electrochemical detection paradigms for neurological drugs and neurotransmitters within the groups referred to as ATC codes N01 to N07. We finally discuss emerging trends and future challenges such as the development of strategies for simultaneous detection of multiple targets with high spatial and temporal resolutions, the integration of microfluidic strategies for selective and localized analyte pre-concentration, the real-time monitoring of neurotransmitter secretions from active cell cultures under electro- and chemotactic cues, aptamer-based biosensors, and the miniaturization of the sensing system for detection in small sample volumes and for enabling cost savings due to manufacturing scale-up. The Electronic Supporting Material (ESM) includes review articles dealing with the review topic in last 40 years, as well as key properties of the analytes, viz., pKa values, half-life of drugs and their electrochemical mechanisms. The ESM also defines analytical figures of merit of the drugs and neurotransmitters. The article contains 198 references in the main manuscript and 207 references in the Electronic Supporting Material.FigureᅟElectronic supplementary materialThe online version of this article (doi:10.1007/s00604-014-1308-4) contains supplementary material, which is available to authorized users.

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Nanocavity Redox Cycling Sensors for the Detection of Dopamine Fluctuations in Microfluidic Gradients

Cited by 72 publications

References 33 publications

A dual-plate ITO–ITO generator–collector microtrench sensor: surface activation, spatial separation and suppression of irreversible oxygen and ascorbate interference

A dual-plate ITO–ITO generator–collector microtrench sensor: surface activation, spatial separation and suppression of irreversible oxygen and ascorbate interference

Nanocavity crossbar arrays for parallel electrochemical sensing on a chip

Nanomaterial-based electrochemical sensing of neurological drugs and neurotransmitters

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