Silver-Colloid-Nucleated Cytochrome <i>c</i> Superstructures Encapsulated in Silica Nanoarchitectures

Wallace, Jean Marie; Dening, Brett M.; Eden, Kristin; Stroud, Rhonda M.; Long, Jeffrey W.; Rolison, Debra R.

doi:10.1021/la048478u

Cited by 27 publications

(49 citation statements)

References 22 publications

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“…Franzen, Feldheim, and coworkers [45] also found that adsorption of a peptide-modified BSA does not saturate with increasing protein concentration, which indicates that more than a monolayer of protein is adsorbing to the nanoparticles. Extensive protein multilayers have been observed previously for cytochrome c on Ag nanoparticles, although these structures were observed under special circumstances including aerogel formation, which may have stabilized their formation [52,53].…”

Section: Quantification Of Bound Hrp and F-hrpmentioning

confidence: 75%

Synthesis and characterization of enzyme-Au bioconjugates: HRP and fluorescein-labeled HRP

et al. 2007

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Enzyme adsorption to Au nanoparticles is important for bioanalytical, catalytic, and biotechnological applications. In this manuscript, adsorption of horseradish peroxidase (HRP) and fluorescein labeled HRP (F-HRP) to colloidal Au nanoparticles is compared. Flocculation analysis indicates some differences in adsorption behavior for the labeled and unlabeled enzymes, particularly at pH 8.0, and to a lesser extent also, at pH 4.0. Zeta potential measurements were quite similar for HRP and F-HRP and leveled off at lower enzyme:Au ratios than observed by flocculation, particularly for pH 6.0 and 8.0. Direct quantification of bound F-HRP was performed by dissolution of Au nanoparticles before fluorescence measurements. We observed F-HRP binding at greater than monolayer coverage on the particles and did not reach saturation even at high solution F-HRP:Au ratios. Indirect quantification of bound unlabeled HRP based on supernatant analysis followed similar trends. More than 50% of the specific enzyme activity was retained for conjugates with a low HRP coverage. With increasing enzyme coverage, the specific activity decreased significantly; however, the total activity per particle remained nearly constant. These findings suggest HRP multilayer formation on the Au nanoparticles, with the outermost layer of HRP contributing to the major part of the conjugate enzyme activity.

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Section: Quantification Of Bound Hrp and F-hrpmentioning

confidence: 75%

Synthesis and characterization of enzyme-Au bioconjugates: HRP and fluorescein-labeled HRP

et al. 2007

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“…This work showed that the defect density of SAMs on the gold substrates created from NP films can have a significant impact in how those SAMs can be used or how they perform in a specific application like protein monolayer electrochemistry where it can impact the signal-to-background of the voltammetry. By better understanding the properties of SAMs that form on the NP-based gold, one can begin to engineer these methods for application to three-dimensional or porous materials applications [58,59].…”

Section: Discussionmentioning

confidence: 99%

Electrochemical characterization of self-assembled monolayers on gold substrates derived from thermal decomposition of monolayer-protected cluster films

et al. 2015

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Networked films of monolayer-protected clusters (MPCs), alkanethiolate-stabilized gold nanoparticles, can be thermally decomposed to form stable gold on glass substrates that are subsequently modified with self-assembled monolayers (SAMs) for use as modified electrodes. Electrochemical assessment of these SAM-modified gold substrates, including double-layer capacitance measurements, linear sweep desorption of the alkanethiolates, and diffusional redox probing, all show that SAMs formed on gold supports formed from thermolysis of MPC films possess substantially higher defect density compared to SAMs formed on traditional evaporated gold. The density of defects in the SAMs on thermolyzed gold is directly related to the strategies used to assemble the MPC film prior to thermolysis. Specifically, gold substrates formed from thermally decomposing MPC films formed with electrostatic bridges between carboxylic acid-modified MPCs and metal ion linkers are particularly sensitive to the degree of metal exposure during the assembly process. While specific metal dependence was observed, metal concentration within the MPC precursor film was determined to be a more significant factor. Specific MPC film linking strategies and pretreatment methods that emphasized lower metal exposure resulted in gold films that supported SAMs of lower defect density. The defect density of a SAM-modified electrode is shown to be critical in certain electrochemical experiments such as protein monolayer electrochemistry of adsorbed cytochrome c. While the thermal decomposition of nanoparticle film assemblies remains a viable and interesting technique for coating both flat and irregular shaped substrates, this study provides electrochemical assessment tools and tactics for determining and controlling SAM defect density on this type of gold structure, a property critical to their effective use in subsequent electrochemical applications.

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“…22 Citrate-capped palladium nanoparticles have only recently been reported in the literature because palladium is an unstable system when compared with other precious metal catalysts like gold and platinum, and tends to agglomerate with other nanoparticles into larger particles. 21 The following optimized protocol is the result of a series of attempts to produce stable palladium nanoparticles.…”

Section: Palladium Synthesismentioning

confidence: 99%

Development and Implementation of Carbon Nanofoam Cathode Structures for Magnesium-Hydrogen Peroxide Semi-Fuel Cells

Renninger¹

2008

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including g the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of the collection of information, including suggestions for reducing this burden to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and ABSTRACT(cont from p. 1) and the extent of thiophenylation in the interior of the nanofoam paper has been improved by elevating the reflux temperature from 50 ºC to 70 ºC. Palladium nanoparticles are synthesized by chemically reducing 2.2 mM sodium tetrachloropalladate with sodium borohydride (NaBH4) in the presence of sodium citrate as a stabilizing ligand. The diameter of the diversiform nanoparticles is tuned between 4-11 nm by varying the ratio of Pd:citrate, and citrate-capped colloidal suspensions remain stable for months. Palladium-decorated carbon nanofoam papers behave as electrochemical double-layer capacitors in 0.2 M H2SO4/simulated brine, but electrochemically reduce H2O2 twice as effectively as bare carbon nanofoams, while only containing ~0.2 wt% (~4 μg Pd cm-2). All accessible and electrifiable Pd nanoparticles in the nanofoam scaffold are simultaneously utilized, as determined by comparing the maximum reduction current at increasing peroxide concentrations and with increased rotation rates. Future experiments will seek to boost the carbon conductivity and the Pd loading to improve electrochemical performance. A rotating disc electrode configuration was used for all electrochemical measurements to maximize the flux of fuel to the electrode surfaces. Palladium contents were determined by ICP-MS and electrochemical performances were normalized to the total mass of each electrode.

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Silver-Colloid-Nucleated Cytochrome c Superstructures Encapsulated in Silica Nanoarchitectures

Cited by 27 publications

References 22 publications

Synthesis and characterization of enzyme-Au bioconjugates: HRP and fluorescein-labeled HRP

Synthesis and characterization of enzyme-Au bioconjugates: HRP and fluorescein-labeled HRP

Electrochemical characterization of self-assembled monolayers on gold substrates derived from thermal decomposition of monolayer-protected cluster films

Development and Implementation of Carbon Nanofoam Cathode Structures for Magnesium-Hydrogen Peroxide Semi-Fuel Cells

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