Nanoporous Gold and Other Related Materials

A special issue of Nanomaterials (ISSN 2079-4991).

Deadline for manuscript submissions: closed (30 April 2018) | Viewed by 38422

Special Issue Editor

Department of Chemistry and Biochemistry, University of Missouri–Saint Louis, Saint Louis, MO 63121, USA
Interests: surface modification; nanomaterials; porous materials; electrochemistry; microscopy; carbohydrates; lipids; biosensors
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Nanoporous gold and other related nanoporous metals or porous nanoparticle assemblies have gained a great deal of attention in recent years due to their novel chemical, optical, and mechanical properties. Nanoporous gold has found application as a support for biomolecules for biosensor development, as a catalyst for oxidation of small molecules, as a material with plasmonic properties useful for optical sensing, as a matrix for controlled release, as a mechanical actuator, and in other areas. Many studies have focused on tuning the porosity of the material, and on studying the relationship between the porosity and the mechanical properties of the material. The material provides a high surface area on which formation of self-assembled monolayers can be performed to impart recognition properties for molecular binding or transport. Nanoporous gold is part of a group of materials known as nanoporous metals which are generally formed by dealloying processes. Nanoporous forms of metals other than gold also have interesting catalytic and optical properties. Related materials with porosity can be formed through the large-scale assembly of nanoparticles. This Special Issue is devoted to the preparation, characterization and application of these nanomaterials.

Prof. Dr. Keith J. Stine
Guest Editor

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Keywords

  • nanoporous gold
  • nanoporous metal
  • dealloying
  • catalysis
  • biomolecule immobilization
  • chemical sensor
  • biosensor

Published Papers (9 papers)

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Editorial

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3 pages, 152 KiB  
Editorial
Nanoporous Gold and Other Related Materials
by Keith J. Stine
Nanomaterials 2019, 9(8), 1080; https://doi.org/10.3390/nano9081080 - 27 Jul 2019
Cited by 9 | Viewed by 2140
Abstract
The field of nanomaterials continues to expand with the discovery of new nanostructures opening up new possibilities for both the study of unique physical properties and new applications [...] Full article
(This article belongs to the Special Issue Nanoporous Gold and Other Related Materials)

Research

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12 pages, 2682 KiB  
Communication
A Microfluidic Platform to Study Astrocyte Adhesion on Nanoporous Gold Thin Films
by Alexander E. Hampe, Zidong Li, Sunjay Sethi, Pamela J. Lein and Erkin Seker
Nanomaterials 2018, 8(7), 452; https://doi.org/10.3390/nano8070452 - 21 Jun 2018
Cited by 8 | Viewed by 2944
Abstract
Nanoporous gold (np-Au) electrode coatings have shown improved neural electrophysiological recording fidelity in vitro, in part due to reduced surface coverage by astrocytes. This reduction in astrocytic spreading has been attributed to the influence of electrode nanostructure on focal adhesion (FA) formation. This [...] Read more.
Nanoporous gold (np-Au) electrode coatings have shown improved neural electrophysiological recording fidelity in vitro, in part due to reduced surface coverage by astrocytes. This reduction in astrocytic spreading has been attributed to the influence of electrode nanostructure on focal adhesion (FA) formation. This study describes the development and use of a microfluidic flow cell for imposing controllable hydrodynamic shear on astrocytes cultured on gold surfaces of different morphologies, in order to study the influence of nanostructure on astrocyte adhesion strength as a function of np-Au electrode morphology. Astrocyte detachment (a surrogate for adhesion strength) monotonically increased as feature size was reduced from planar surfaces to np-Au, demonstrating that adhesion strength is dependent on nanostructure. Putative mechanisms responsible for this nanostructure-driven detachment phenomenon are also discussed. Full article
(This article belongs to the Special Issue Nanoporous Gold and Other Related Materials)
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9 pages, 2104 KiB  
Article
(9R)-9-Hydroxystearate-Functionalized Anticancer Ceramics Promote Loading of Silver Nanoparticles
by Elisa Boanini, Maria Cristina Cassani, Katia Rubini, Carla Boga and Adriana Bigi
Nanomaterials 2018, 8(6), 390; https://doi.org/10.3390/nano8060390 - 31 May 2018
Cited by 11 | Viewed by 2740
Abstract
Functionalization of calcium phosphates for biomedical applications has been proposed as a strategy to enrich the good osteoinductive properties of these materials with specific therapeutic characteristics. Herein, we prepared and characterized hydroxyapatite nanocrystals functionalized with an anticancer agent, (9R)-9-hydroxystearate (HSA), and [...] Read more.
Functionalization of calcium phosphates for biomedical applications has been proposed as a strategy to enrich the good osteoinductive properties of these materials with specific therapeutic characteristics. Herein, we prepared and characterized hydroxyapatite nanocrystals functionalized with an anticancer agent, (9R)-9-hydroxystearate (HSA), and loaded with an antimicrobial agent, namely silver nanoparticles (AgNPs). Nanocrystals at two different contents of HSA, about 4 and 9 wt %, were prepared via direct synthesis in aqueous solution. Loading with the antibacterial agent was achieved through interaction with different volumes of AgNPs suspensions. The amount of loaded nanoparticles increases with the volume of the AgNPs suspension and with the hydroxystearate content of the nanocrystals, up to about 3.3 wt %. The structural, morphological, and hydrophobic properties of the composite materials depend on hydroxystearate content, whereas they are not affected by AgNPs loading. At variance, the values of zeta potential slightly increase with the content of AgNPs, which exhibit a sustained release in cell culture medium. Full article
(This article belongs to the Special Issue Nanoporous Gold and Other Related Materials)
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12 pages, 3433 KiB  
Article
High Temperature Flow Behavior of Ultra-Strong Nanoporous Au assessed by Spherical Nanoindentation
by Alexander Leitner, Verena Maier-Kiener and Daniel Kiener
Nanomaterials 2018, 8(6), 366; https://doi.org/10.3390/nano8060366 - 24 May 2018
Cited by 6 | Viewed by 4286
Abstract
Nanoporous metals have attracted attention in various research fields in the past years since their unique microstructures make them favorable for catalytic, sensory or microelectronic applications. Moreover, the refinement of the ligaments down to the nanoscale leads to an exceptionally high strength. To [...] Read more.
Nanoporous metals have attracted attention in various research fields in the past years since their unique microstructures make them favorable for catalytic, sensory or microelectronic applications. Moreover, the refinement of the ligaments down to the nanoscale leads to an exceptionally high strength. To guarantee a smooth implementation of nanoporous metals into modern devices their thermo-mechanical behavior must be properly understood. Within this study the mechanical flow properties of nanoporous Au were investigated at elevated temperatures up to 300 °C. In contrast to the conventional synthesis by dealloying of AuAg precursors, the present foam was fabricated via severe plastic deformation of an AuFe nanocomposite and subsequent selective etching of iron, resulting in Au ligaments consisting of nanocrystalline grains, while remaining Fe impurities excessively stabilize the microstructure. A recently developed spherical nanoindentation protocol was used to extract the stress-strain curves of nanoporous Au. A tremendous increase of yield strength due to ligament and grain refinement was observed, which is largely maintained at high temperatures. Reviewing literature will evidence that the combined nanocrystalline and nanoporous structure leads to remarkable mechanical properties. Furthermore, comparison to a previous Berkovich nanoindentation study outlines the conformity of different indentation techniques. Full article
(This article belongs to the Special Issue Nanoporous Gold and Other Related Materials)
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18 pages, 4391 KiB  
Article
Electrically Guided DNA Immobilization and Multiplexed DNA Detection with Nanoporous Gold Electrodes
by Jovana Veselinovic, Zidong Li, Pallavi Daggumati and Erkin Seker
Nanomaterials 2018, 8(5), 351; https://doi.org/10.3390/nano8050351 - 21 May 2018
Cited by 20 | Viewed by 5645
Abstract
Molecular diagnostics have significantly advanced the early detection of diseases, where the electrochemical sensing of biomarkers (e.g., DNA, RNA, proteins) using multiple electrode arrays (MEAs) has shown considerable promise. Nanostructuring the electrode surface results in higher surface coverage of capture probes and more [...] Read more.
Molecular diagnostics have significantly advanced the early detection of diseases, where the electrochemical sensing of biomarkers (e.g., DNA, RNA, proteins) using multiple electrode arrays (MEAs) has shown considerable promise. Nanostructuring the electrode surface results in higher surface coverage of capture probes and more favorable orientation, as well as transport phenomena unique to nanoscale, ultimately leading to enhanced sensor performance. The central goal of this study is to investigate the influence of electrode nanostructure on electrically-guided immobilization of DNA probes for nucleic acid detection in a multiplexed format. To that end, we used nanoporous gold (np-Au) electrodes that reduced the limit of detection (LOD) for DNA targets by two orders of magnitude compared to their planar counterparts, where the LOD was further improved by an additional order of magnitude after reducing the electrode diameter. The reduced electrode diameter also made it possible to create a np-Au MEA encapsulated in a microfluidic channel. The electro-grafting reduced the necessary incubation time to immobilize DNA probes into the porous electrodes down to 10 min (25-fold reduction compared to passive immobilization) and allowed for grafting a different DNA probe sequence onto each electrode in the array. The resulting platform was successfully used for the multiplexed detection of three different biomarker genes relevant to breast cancer diagnosis. Full article
(This article belongs to the Special Issue Nanoporous Gold and Other Related Materials)
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12 pages, 8078 KiB  
Article
Novel Gold Dendritic Nanoforests Combined with Titanium Nitride for Visible-Light-Enhanced Chemical Degradation
by Ming-Hua Shiao, Chun-Ting Lin, Jian-Jia Zeng and Yung-Sheng Lin
Nanomaterials 2018, 8(5), 282; https://doi.org/10.3390/nano8050282 - 26 Apr 2018
Cited by 14 | Viewed by 4985
Abstract
In this study, gold dendritic nanoforests (Au DNFs)-titanium nitride (TiN) composite was firstly proposed for visible-light photodegradation of pollutants. A high-power impulse magnetron sputtering system was used to coat TiN films on silicon wafers, and a fluoride-assisted galvanic replacement reaction was applied to [...] Read more.
In this study, gold dendritic nanoforests (Au DNFs)-titanium nitride (TiN) composite was firstly proposed for visible-light photodegradation of pollutants. A high-power impulse magnetron sputtering system was used to coat TiN films on silicon wafers, and a fluoride-assisted galvanic replacement reaction was applied to deposit Au DNFs on TiN/Si substrates. Scanning electron microscope images and X-ray diffraction patterns of TiN/Si, Au DNFs/Si, and Au DNFs/TiN/Si samples verified that this synthesis process was accurately controlled. The average reflectance of Au DNFs/Si and Au DNFs/TiN/Si considerably declined to approximately 10%, because the broadband localized surface plasmon resonances of Au DNFs cause broadband absorbance and low reflectance. In photocatalytic performance, 90.66 ± 1.41% 4-nitrophenol was successfully degraded in 180 min by Au DNFs/TiN/Si under visible-light irradiation. Therefore, Au DNFs/TiN/Si has the chance to be a visible-light photocatalyst for photodegradation of pollutants. Full article
(This article belongs to the Special Issue Nanoporous Gold and Other Related Materials)
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4239 KiB  
Article
Constructing Asymmetric Polyion Complex Vesicles via Template Assembling Strategy: Formulation Control and Tunable Permeability
by Junbo Li, Lijuan Liang, Ju Liang, Wenlan Wu, Huiyun Zhou and Jinwu Guo
Nanomaterials 2017, 7(11), 387; https://doi.org/10.3390/nano7110387 - 13 Nov 2017
Cited by 6 | Viewed by 3860
Abstract
A strategy for constructing polyion complex vesicles (PICsomes) with asymmetric structure is described. Poly(methylacrylic acid)-block-poly(N-isopropylacrylamide) modified gold nanoparticles (PMAA-b-PNIPAm-@-Au NPs) were prepared and then assembled with poly(ethylene glycol)-block-poly[1-methyl-3-(2-methacryloyloxy propylimidazolium bromine)] (PEG-b-PMMPImB) via polyion [...] Read more.
A strategy for constructing polyion complex vesicles (PICsomes) with asymmetric structure is described. Poly(methylacrylic acid)-block-poly(N-isopropylacrylamide) modified gold nanoparticles (PMAA-b-PNIPAm-@-Au NPs) were prepared and then assembled with poly(ethylene glycol)-block-poly[1-methyl-3-(2-methacryloyloxy propylimidazolium bromine)] (PEG-b-PMMPImB) via polyion complex of PMMA and PMMPImB. After removing the Au NPs template, asymmetric PICsomes composed of a PNIPAm inner-shell, PIC wall, and PEG outer-corona were obtained. These PICsomes have low protein absorption and thermally tunable permeability, provided by the PEG outer-corona and the PNIPAm inner-shell, respectively. Moreover, PICsome size can be tailored by using templates of predetermined sizes. This novel strategy for constructing asymmetric PICsomes with well-defined properties and controllable size is valuable for applications such as drug delivery, catalysis and monitoring of chemical reactions, and biomimetics. Full article
(This article belongs to the Special Issue Nanoporous Gold and Other Related Materials)
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7188 KiB  
Article
Controlling the Mechanical Properties of Bulk Metallic Glasses by Superficial Dealloyed Layer
by Chaoyang Wang, Man Li, Mo Zhu, Han Wang, Chunling Qin, Weimin Zhao and Zhifeng Wang
Nanomaterials 2017, 7(11), 352; https://doi.org/10.3390/nano7110352 - 27 Oct 2017
Cited by 9 | Viewed by 3228
Abstract
Cu50Zr45Al5 bulk metallic glass (BMG) presents high fracture strength. For improving its plasticity and controlling its mechanical properties, superficial dealloying of the BMG was performed. A composite structure containing an inner rod-shaped Cu-Zr-Al amorphous core with high strength [...] Read more.
Cu50Zr45Al5 bulk metallic glass (BMG) presents high fracture strength. For improving its plasticity and controlling its mechanical properties, superficial dealloying of the BMG was performed. A composite structure containing an inner rod-shaped Cu-Zr-Al amorphous core with high strength and an outer dealloyed nanoporous layer with high energy absorption capacity was obtained. The microstructures and mechanical properties of the composites were studied in detail. It was found, for the first time, that the mechanical properties of Cu50Zr45Al5 BMG can be controlled by adjusting the width of the buffer deformation zone in the dealloyed layer, which can be easily manipulated with different dealloying times. As a result, the compressive strength, compressive strain, and energy absorption capacity of the BMGs can be effectively modulated from 0.9 to 1.5 GPa, from 2.9% to 4.7%, and from 29.1 to 40.2 MJ/m3, respectively. The paper may open a door for developing important engineering materials with regulable and comprehensive performances. Full article
(This article belongs to the Special Issue Nanoporous Gold and Other Related Materials)
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Review

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29 pages, 4734 KiB  
Review
Preparation, Modification, Characterization, and Biosensing Application of Nanoporous Gold Using Electrochemical Techniques
by Jay K. Bhattarai, Dharmendra Neupane, Bishal Nepal, Vasilii Mikhaylov, Alexei V. Demchenko and Keith J. Stine
Nanomaterials 2018, 8(3), 171; https://doi.org/10.3390/nano8030171 - 16 Mar 2018
Cited by 60 | Viewed by 7631
Abstract
Nanoporous gold (np-Au), because of its high surface area-to-volume ratio, excellent conductivity, chemical inertness, physical stability, biocompatibility, easily tunable pores, and plasmonic properties, has attracted much interested in the field of nanotechnology. It has promising applications in the fields of catalysis, bio/chemical sensing, [...] Read more.
Nanoporous gold (np-Au), because of its high surface area-to-volume ratio, excellent conductivity, chemical inertness, physical stability, biocompatibility, easily tunable pores, and plasmonic properties, has attracted much interested in the field of nanotechnology. It has promising applications in the fields of catalysis, bio/chemical sensing, drug delivery, biomolecules separation and purification, fuel cell development, surface-chemistry-driven actuation, and supercapacitor design. Many chemical and electrochemical procedures are known for the preparation of np-Au. Recently, researchers are focusing on easier and controlled ways to tune the pores and ligaments size of np-Au for its use in different applications. Electrochemical methods have good control over fine-tuning pore and ligament sizes. The np-Au electrodes that are prepared using electrochemical techniques are robust and are easier to handle for their use in electrochemical biosensing. Here, we review different electrochemical strategies for the preparation, post-modification, and characterization of np-Au along with the synergistic use of both electrochemistry and np-Au for applications in biosensing. Full article
(This article belongs to the Special Issue Nanoporous Gold and Other Related Materials)
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