Observation of Single Metal Nanoparticle Collisions by Open Circuit (Mixed) Potential Changes at an Ultramicroelectrode

Zhou, Hongjun; Park, Jun Hui; Fan, Fu‐Ren F.; Bard, Allen J.

doi:10.1021/ja305573g

Cited by 123 publications

(146 citation statements)

References 18 publications

(27 reference statements)

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“…Bard and co-workers previously reported the observation of a spike-shaped i−t response in the case of water oxidation with IrO x NPs at a Au UME and suggested that the NP bounces off the electrode rather than remaining stuck on the electrode surface. 10 Assuming that the sharp current spikes due to proton reduction with citrate-capped Pt NPs at Hg/Pt UME are due to electrostatic repulsion and are not specific to Hg, one would expect to observe a similar i−t response under similar conditions with a different electrode material such as Bi. To test this hypothesis, proton reduction experiments were performed at Bi/Pt UMEs with the same citrate-capped Pt NPs.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Influence of the Redox Indicator Reaction on Single-Nanoparticle Collisions at Mercury- and Bismuth-Modified Pt Ultramicroelectrodes

et al. 2013

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Single-Pt nanoparticles (NPs) can be detected electrochemically by measuring the current-time (i-t) response associated with both hydrazine oxidation and proton reduction during individual Pt NP collisions with noncatalytic Hg- and Bi-modified Pt ultramicroelectrodes (Hg/Pt and Bi/Pt UMEs, respectively). At Hg/Pt UMEs, the i-t response for both hydrazine oxidation and proton reduction consists of repeated current "spikes" that return to the background level as Hg poisons the Pt NP after collision with the Hg/Pt UME due to amalgamation and deactivation of the redox reaction. Furthermore, at a Hg/Pt UME, the applied potential directly influences the interfacial surface tension (electrocapillarity) that also impacts the observed i-t response for single-Pt NP collisions for proton reduction that exhibits a faster decay of current (0.7-4 ms) to background levels than hydrazine oxidation (2-5 s). Because the surface tension of Hg is lower (-0.9 V), Pt NPs possibly react faster with Hg (amalgamate at a faster rate), resulting in sharp current spikes for proton reduction compared to hydrazine oxidation. In contrast, a stepwise "staircase" i-t response is observed for proton reduction for single-Pt NP collisions at a Bi/Pt UME. This different response suggests that electrostatic forces of negatively charged citrate-capped Pt NPs also influence the i-t response at more negative applied potentials, but the Pt NPs do not poison the electrochemical activity at Bi/Pt UMEs.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Influence of the Redox Indicator Reaction on Single-Nanoparticle Collisions at Mercury- and Bismuth-Modified Pt Ultramicroelectrodes

et al. 2013

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“…Experiments typically employ a Faradaically-inactive electrode that is exposed to a solution, which contains freely-diffusing nanoparticles. [4][5][6][7][8][9] Due to the nanoparticles' random Brownian motion, particles then stochastically impact on the biased electrode and briey adopt the electrode potential while they are located within tunnelling distance to the electrode. During the moment of impact, nanoparticles may then enable a Faradaic current via either a reaction resulting from the particle's intrinsic electrochemical properties or via a catalytic reaction.…”

Section: Introductionmentioning

confidence: 99%

Understanding nano-impacts: impact times and near-wall hindered diffusion

Kätelhön¹,

Compton²

2014

Chem. Sci.

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We report the residence time of freely-diffusing, catalytically-active nanoparticles within a electron tunnelling distance of a surface. The role of near-wall hindered diffusion is paramount and leads to the new concept of "hydrodynamic adsorption". We give a comprehensive statistical analysis of the average impact times and derive expressions for a number values, crucial for the analysis of experimental data.Random walk simulations confirm the distribution of impact times with broad implications for nanochemistry.

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“…The interested reader can consult the references for a discussion on each of the techniques used to observe stochastic events electrochemically: blocking (9, 13), electrocatalytic amplification (1), open circuit potential (16), droplet blocking/reactor (13,14), and ECL (15,17,18). The simplest and most reproducible method of observing collisions is a technique termed blocking, which is so named because particles, which are brought to the electrode by a diffusion-limited flux and/or electrophoretic migration, irreversibly adsorb (1) to the electrode surface, blocking the flux of redox active species.…”

mentioning

confidence: 99%

Electrochemical detection of a single cytomegalovirus at an ultramicroelectrode and its antibody anchoring

Dick

Hilterbrand

Boika

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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147

132

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We report observations of stochastic collisions of murine cytomegalovirus (MCMV) on ultramicroelectrodes (UMEs), extending the observation of discrete collision events on UMEs to biologically relevant analytes. Adsorption of an antibody specific for a virion surface glycoprotein allowed differentiation of MCMV from MCMV bound by antibody from the collision frequency decrease and current magnitudes in the electrochemical collision experiments, which shows the efficacy of the method to size viral samples. To add selectivity to the technique, interactions between MCMV, a glycoprotein-specific primary antibody to MCMV, and polystyrene bead "anchors," which were functionalized with a secondary antibody specific to the Fc region of the primary antibody, were used to affect virus mobility. Bead aggregation was observed, and the extent of aggregation was measured using the electrochemical collision technique. Scanning electron microscopy and optical microscopy further supported aggregate shape and extent of aggregation with and without MCMV. This work extends the field of collisions to biologically relevant antigens and provides a novel foundation upon which qualitative sensor technology might be built for selective detection of viruses and other biologically relevant analytes.collisions | cytomegalovirus | electrochemistry | murine cytomegalovirus | virus O ver the past decade, the study of discrete collision events on ultramicroelectrodes (UMEs) has gained attention due to the interest in understanding stochastic phenomena by electrochemistry. By observing the collisions of small particles, there is the possibility that information can be deduced that is not available in ensemble measurements. The electrochemical study of single collision events has been applied to a wide range of hard nanoparticles (NPs), which include metal, metal oxide, and organic NPs [platinum (1), silver (2), gold (3), nickel (4), copper (5), iridium oxide (6), cerium oxide (7), titanium oxide (8), silicon oxide (9), indigo (10), polystyrene (11), and relatively large aggregates of fullerene (12)]. Recently, collisions of soft particles have been investigated, such as toluene droplets (13) and liposomes (14). Also, collisions of toluene and tri-n-propylamine droplets were observed simultaneously by both electrochemical and electrogenerated chemiluminescent (ECL) measurements (15).Similarly, a variety of techniques have been developed to observe these collision events. The interested reader can consult the references for a discussion on each of the techniques used to observe stochastic events electrochemically: blocking (9, 13), electrocatalytic amplification (1), open circuit potential (16), droplet blocking/reactor (13,14), and ECL (15,17,18). The simplest and most reproducible method of observing collisions is a technique termed blocking, which is so named because particles, which are brought to the electrode by a diffusion-limited flux and/or electrophoretic migration, irreversibly adsorb (1) to the electrode surface, blocking the flux of red...

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Observation of Single Metal Nanoparticle Collisions by Open Circuit (Mixed) Potential Changes at an Ultramicroelectrode

Cited by 123 publications

References 18 publications

Influence of the Redox Indicator Reaction on Single-Nanoparticle Collisions at Mercury- and Bismuth-Modified Pt Ultramicroelectrodes

Influence of the Redox Indicator Reaction on Single-Nanoparticle Collisions at Mercury- and Bismuth-Modified Pt Ultramicroelectrodes

Understanding nano-impacts: impact times and near-wall hindered diffusion

Electrochemical detection of a single cytomegalovirus at an ultramicroelectrode and its antibody anchoring

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