Electrically tunable pore morphology in nanoporous gold thin films

Dorofeeva, Tatiana S.; Şeker, Erkin

doi:10.1007/s12274-015-0726-x

Cited by 23 publications

(32 citation statements)

References 41 publications

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“…Np-Au is a nanostructured material that is produced by selective dissolution of silver from a gold-silver alloy, resulting in a network of gold ligaments and pores. 11, 31 Specifically, np-Au has attracted attention for its applications in electrochemical sensors, 12, 22, 29 catalytic platforms, 18 fundamental nanoscale materials studies, 6, 10 tunable drug release, 21 and high fidelity recordings from organotypic brain slices. 30 These properties, along with its compatibility with microfabrication techniques, suggest np-Au as an attractive option for high sensitivity multifunctional biosensors with potential applications ranging from lab-on-a-chip based field devices to implantable drug-eluting neural electrodes.…”

Section: Introductionmentioning

confidence: 99%

Mechanisms of Reduced Astrocyte Surface Coverage in Cortical Neuron-Glia Co-cultures on Nanoporous Gold Surfaces

et al. 2016

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Nanoporous gold (np-Au) is a promising multifunctional material for neural electrodes. We have previously shown that np-Au nanotopography reduces astrocyte surface coverage (linked to undesirable gliosis) while maintaining high neuronal coverage in a cortical primary neuron-glia co-culture model as long as two weeks in vitro. Here, we investigate the potential influence of secreted soluble factors from cells grown on np-Au on the cell type-specific surface coverage of cells grown on conventional tissue culture plastic and test the hypothesis that secretion of factors is responsible for inhibiting astrocyte coverage on np-Au. In order to assess whether factors secreted from cells grown on np-Au surfaces reduced surface coverage by astrocytes, we seeded fresh primary rat neuron-glia co-cultures on conventional polystyrene culture dishes, but maintained the cells in conditioned media from co-cultures grown on np-Au surfaces. After one week in vitro, a preferential reduction in astrocyte surface coverage was not observed, suggesting that soluble factors are not playing a role. In contrast, four hours after cell seeding there were a significant number of non-adhered, yet still viable, cells for the cultures on np-Au surfaces. We hypothesize that the non-adherent cells are mainly astrocytes, because: (i) there was no difference in neuronal cell coverage between np-Au and pl-Au for long culture durations and (ii) neurons are post-mitotic and not expected to increase in number upon attaching to the surface. Overall, the results suggest that the np-Au topography leads to preferential neuronal attachment shortly after cell seeding and limits astrocyte-specific np-Au surface coverage at longer culture durations.

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Section: Introductionmentioning

confidence: 99%

Mechanisms of Reduced Astrocyte Surface Coverage in Cortical Neuron-Glia Co-cultures on Nanoporous Gold Surfaces

et al. 2016

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“…Top views were converted to binary images and ligament and pore sizes were calculated using custom MatLab scripts and ImageJ software, using methods previously described 19 . .…”

Section: Morphological Characterizationmentioning

confidence: 99%

“…As a model system for nanoporous metals produced by dealloying, we use nanoporous gold (np-Au), which has been the most popular material system as it embodies numerous advantages, including high electrical conductivity 22 , compatibility with microfabrication processes 19 , well-established gold-thiol chemistry for surface functionalization 23 , tunable mechanical properties [24][25] , and biocompatibility 26 . By employing electrochemical etching at time-varying potentials, we probe the underlying etch mechanisms and discuss its implications to catalysis and sensing applications.…”

Section: Introductionmentioning

confidence: 99%

Electrochemically Triggered Pore Expansion in Nanoporous Gold Thin Films

et al. 2016

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Nanoporous electrode coatings have played a significant role in enhancing the performance of catalysts and sensors. For optimal performance in these applications, the fundamental requirement is a large effective surface area (site at which catalysis and sensing events occur) with unhindered transport of reactants and products to/from the active surface. This necessitates low-density porous electrodes with an interconnected 3D network of thin conductive ligaments to maintain high effective surface area. While the logical approach to create such electrodes is to etch the ligaments uniformly through the entire porous network, accomplishing this has not been trivial. Here, we use nanoporous gold (np-Au) as a model material system to demonstrate an electrochemically-triggered etching method for restructuring sputter-deposited sub-micron np-Au thin films for enlarging the pores with minimal decrease in the effective surface area. We systematically employ time-varying potential waveforms to electrochemically modify morphologies and reveal underlying mechanisms of the etching process. The results suggest that the etch cycle at positive potentials plays a dual role of electrophoretic attraction of chloride ions and initiating the electrochemical etch. The final nanoporous morphology is dictated by a competition between ligament coarsening and ligament thinning, which provide a means to generate a wide range of electrode morphologies.

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“…Nanoporous gold (np-Au) has potential use in various technological applications because of its properties that include a high surface-to-volume ratio, a wide range of formats from thin films to large monoliths, and a tunable pore size which is easily controlled by thermal annealing treatment, acid treatment or by electrochemical methods [1–3]. Np-Au is prepared by dealloying in which any of a variety of less noble elements, such as Ag, Cu, Zn and others are removed from a precursor alloy of typically at least 20 to not more than 50 atomic percent gold [4, 5].…”

Section: Introductionmentioning

confidence: 99%

Electrochemical impedance spectroscopy study of carbohydrate-terminated alkanethiol monolayers on nanoporous gold: Implications for pore wetting

Sharma

Bhattarai

Nigudkar

et al. 2016

Journal of Electroanalytical Chemistry

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Electrochemical impedance spectroscopy (EIS) is used to compare the apparent electron transfer rate constant (kapp) for a series of alkanethiol and of carbohydrate-terminated alkanethiol self-assembled monolayers (SAMs) on both flat gold and on nanoporous gold (np-Au). Using the surface area for np-Au determined by oxide stripping, the values of kapp for the alkanethiol modified np-Au are initially over two orders of magnitude smaller than the values found on flat Au. This result provides evidence that the diffusing redox probe Fe(CN)63−/4− only accesses a fraction of the np-Au surface after alkanethiol modification suggesting very limited wetting of the internal pores due to the hydrophobic nature of these surfaces. In contrast, for np-Au modified by carbohydrate-terminated (mannose or galactose) alkanethiols the values of kapp are about 10–40 fold smaller than on flat gold, suggesting more extensive access of the diffusing redox probe within the pores and better but still incomplete wetting, a result also found for modification of np-Au with mercaptododecanoic acid. A short chain PEG thiol derivative is found to result in a comparison of kapp values that suggests nearly complete wetting of the internal pores for this highly hydrophilic derivative. These results are of significance for the potential applications of SAM modified np-Au in electrochemical sensors, especially for those based on carbohydrate–protein recognition, or those of np-Au modified by SAMs with polar terminal groups.

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Electrically tunable pore morphology in nanoporous gold thin films

Cited by 23 publications

References 41 publications

Mechanisms of Reduced Astrocyte Surface Coverage in Cortical Neuron-Glia Co-cultures on Nanoporous Gold Surfaces

Mechanisms of Reduced Astrocyte Surface Coverage in Cortical Neuron-Glia Co-cultures on Nanoporous Gold Surfaces

Electrochemically Triggered Pore Expansion in Nanoporous Gold Thin Films

Electrochemical impedance spectroscopy study of carbohydrate-terminated alkanethiol monolayers on nanoporous gold: Implications for pore wetting

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