Molecular release from patterned nanoporous gold thin films

Kurtuluş, Özge; Daggumati, Pallavi; Şeker, Erkin

doi:10.1039/c4nr01288g

Cited by 46 publications

(109 citation statements)

References 53 publications

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“…Transport limitations, especially for MB to penetrate the porous structure once dispersed into the electrolyte, are more prominent in np-Au films owing to their highly tortuous structure 21 . Hence the extent of signal reduction was greater in np-Au (65%) compared to planar Au (50%).…”

Section: Interaction Of Mb With Probe-modified Np-au Filmsmentioning

confidence: 99%

Effect of Nanoporous Gold Thin Film Morphology on Electrochemical DNA Sensing

2015

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Advances in materials science and chemistry have led to the development of a wide range of nanostructured materials for building novel electrochemical biosensors. A systematic understanding of the challenges related to electrode morphology involved in designing such sensors is essential for developing effective biosensing tools. In this study, we use nanoporous gold (npAu) thin film electrode coatings with sub-micron thicknesses, as a model system to investigate the influence of nanostructuring on DNA-methylene blue (MB) interactions and their application for DNA biosensors. The interaction of single-and double-stranded DNA immobilized onto morphologically different np-Au films with MB was electrochemically interrogated via square wave voltammetry (SWV). The electrochemical signal from these electrodes in response to MB decayed progressively with each SWV scan. The decay rate was governed by accessibility of the electrochemically-active np-Au surface by the analyte. The optimum frequency for extracting the maximum signal via SWV was influenced by the film morphology, where the optimum frequency was lower for the nanoporous morphology with lower density of molecular access points into the porous coating. Overall, the np-Au electrodes exhibited a 10-fold enhancement in probe grafting density and approximately 10-fold higher electrochemical current upon probetarget hybridization as compared to the planar Au electrodes. The np-Au electrodes enabled sensitive detection with a dynamic range of 10 nM to 100 nM that shifts by an order of magnitude for coarsened np-Au morphology due to increased target penetration into the porous network and hence enhanced hybridization efficiency. These findings provide insight into the influence of nanostructuring on the transport mechanisms of small molecules and nucleic acids, and yield an understanding of diverse sensor performance parameters such as DNA grafting density, hybridization efficiency, sensitivity and dynamic range.

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Section: Interaction Of Mb With Probe-modified Np-au Filmsmentioning

confidence: 99%

Effect of Nanoporous Gold Thin Film Morphology on Electrochemical DNA Sensing

2015

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“…Tensile stress accumulation during the dealloying step results in hairline cracks (large connected darker regions in top SEM view) throughout the film, which were included in the determination of pore width 19 . The influence of cracks on loading capacity and release kinetics have been reported previously 11 . 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 …”

Section: Resultsmentioning

confidence: 99%

“…Our previous work describes the detailed fabrication of patterned np-Au thin films used in the release experiments 11,16 . Briefly, in order to fabricate the release chips (also referred to as release samples) used for molecular release from 3 mm x 3 mm np-Au patterns, we sputtered a stack of metal layers through a laser-cut PDMS stencil mask temporarily placed on glass coverslips.…”

Section: Fabrication and Characterization Of Np-au Release Samplesmentioning

confidence: 99%

“…After the rinse, each chip was placed into a new microcentrifuge tube filled with release medium of interest (DI water or PBS) to initiate fluorescein release from the np-Au chips. At successive time points, 10 μL of solution was sampled from the elution tube (following pipet agitation to ensure homogeneity) and mixed with 10 μL of 50 mM NaOH to enhance fluorescence intensity 11,16 . The fluorescence intensity of the resulting solution was quantified with NanoDrop 3300 fluorospectrometer at a peak emission wavelength of 515 nm.…”

Section: Loading and Molecular Release Quantificationmentioning

confidence: 99%

“…Properties of the drug molecules (e.g., electrical charge, size, chemical reactivity), the materials (e.g., morphology, surface charge), and the liquid medium where the molecules are delivered (e.g., ionic strength, pH) are all crucial factors in dictating drug delivery performance 2,6 . Nanoporous gold (np-Au), with its high effective surface area, well established gold-thiol-mediated surface modifications, and tunable pore morphology, is a promising material for drug delivery applications and studying the influence of physicochemical surface properties on the moleculeloading capacity and release kinetics [8][9][10][11][12][13][14][15] . Our previous studies have focused on the effect of pore morphology and elution medium constituents on the molecular release from np-Au coatings 11,16 .…”

Section: Introductionmentioning

confidence: 99%

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Effect of Surface–Molecule Interactions on Molecular Loading Capacity of Nanoporous Gold Thin Films

Polat

Şeker

2016

J. Phys. Chem. C

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Surface-molecule interactions play an essential role in loading capacity and release kinetics in nanostructured materials with high surface area-to-volume ratio. Engineering the surfaces via immobilizing functional moieties is therefore a versatile means to enhance the performance of drug delivery platforms with nanostructured components. Nanoporous gold (np-Au), with its high effective surface area, well established gold-thiol chemistry, and tunable pore morphology, is an emerging material not only for drug delivery applications but also as a model system to study the influence of physicochemical surface properties on molecular loading capacity and release kinetics. Here, we functionalize np-Au with self-assembled monolayers (SAMs) of alkanethiols with varying functional groups and chain lengths, and use fluorescein (a small-molecule drug surrogate) to provide insight into the relationship between surface properties and molecular release. The results revealed that electrostatic interactions dominate the loading capacity for short SAMs (two carbons). As SAM length increases the loading capacity displays a nonmonotonic dependence on chain length, where for medium-length SAMs (six carbons) allow for higher loading plausibly due to denser SAM surface packing. For longer SAMs (11 carbons), the steric hindrance due to long chains crowds the pores, thereby hampering fluorescein access to the deeper pore layers, consequently reducing loading capacity.

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Nanoporous Gold Biointerfaces: Modifying Nanostructure to Control Neural Cell Coverage and Enhance Electrophysiological Recording Performance

et al. 2016

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Nanostructured neural interface coatings have significantly enhanced recording fidelity in both implantable and in vitro devices. As such, nano-porous gold (np-Au) has shown promise as a multifunctional neural interface coating due, in part, to its ability to promote nanostructure-mediated reduction in astrocytic surface coverage while not affecting neuronal coverage. The goal of this study is to provide insight into the mechanisms by which the np-Au nanostructure drives the differential response of neurons versus astrocytes in an in vitro model. Utilizing microfabricated libraries that display varying feature sizes of np-Au, it is demonstrated that np-Au influ-ences neural cell coverage through modulating focal adhesion formation in a feature size-dependent manner. The results here show that surfaces with small (≈30 nm) features control astrocyte spreading through inhibition of focal adhesion formation, while surfaces with large (≈170 nm and greater) features control astrocyte spreading through other mechanotransduction mechanisms. This cellular response combined with lower electrical impedance of np-Au electrodes significantly enhances the fidelity and stability of electrophysiological recordings from cortical neuronglia co-cultures relative to smooth gold electrodes. Finally, by leveraging the effect of nanostructure on neuronal versus glial cell attachment, the use of laser-based nanostructure modulation is demonstrated for selectively patterning neurons with micrometer spatial resolution.

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Molecular release from patterned nanoporous gold thin films

Cited by 46 publications

References 53 publications

Effect of Nanoporous Gold Thin Film Morphology on Electrochemical DNA Sensing

Effect of Nanoporous Gold Thin Film Morphology on Electrochemical DNA Sensing

Effect of Surface–Molecule Interactions on Molecular Loading Capacity of Nanoporous Gold Thin Films

Nanoporous Gold Biointerfaces: Modifying Nanostructure to Control Neural Cell Coverage and Enhance Electrophysiological Recording Performance

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