Recent Advances in Nanoporous Membranes for Water Purification

PubMed Central

Wang, Zhuqing; Colombi Ciacchi, Lucio

2018-01-01

Nanoporous materials exhibit wide applications in the fields of electrocatalysis, nanodevice fabrication, energy, and environmental science, as well as analytical science. In this review, we present a summary of recent studies on nanoporous membranes for water purification application. The types and fabrication strategies of various nanoporous membranes are first introduced, and then the fabricated nanoporous membranes for removing various water pollutants, such as salt, metallic ions, anions, nanoparticles, organic chemicals, and biological substrates, are demonstrated and discussed. This work will be valuable for readers to understand the design and fabrication of various nanoporous membranes, and their potential purification mechanisms towards different water pollutants. In addition, it will be helpful for developing new nanoporous materials for quick, economic, and high-performance water purification. PMID:29370128

Boosting infrared energy transfer in 3D nanoporous gold antennas.

PubMed

Garoli, D; Calandrini, E; Bozzola, A; Ortolani, M; Cattarin, S; Barison, S; Toma, A; De Angelis, F

2017-01-05

The applications of plasmonics to energy transfer from free-space radiation to molecules are currently limited to the visible region of the electromagnetic spectrum due to the intrinsic optical properties of bulk noble metals that support strong electromagnetic field confinement only close to their plasma frequency in the visible/ultraviolet range. In this work, we show that nanoporous gold can be exploited as a plasmonic material for the mid-infrared region to obtain strong electromagnetic field confinement, co-localized with target molecules into the nanopores and resonant with their vibrational frequency. The effective optical response of the nanoporous metal enables the penetration of optical fields deep into the nanopores, where molecules can be loaded thus achieving a more efficient light-matter coupling if compared to bulk gold. In order to realize plasmonic resonators made of nanoporous gold, we develop a nanofabrication method based on polymeric templates for metal deposition and we obtain antenna arrays resonating at mid-infrared wavelengths selected by design. We then coat the antennas with a thin (3 nm) silica layer acting as the target dielectric layer for optical energy transfer. We study the strength of the light-matter coupling at the vibrational absorption frequency of silica at 1240 cm -1 through the analysis of the experimental Fano lineshape that is benchmarked against identical structures made of bulk gold. The boost in the optical energy transfer from free-space mid-infrared radiation to molecular vibrations in nanoporous 3D nanoantenna arrays can open new application routes for plasmon-enhanced physical-chemical reactions.

Effect of pH on ion current through conical nanopores

NASA Astrophysics Data System (ADS)

Chander, M.; Kumar, R.; Kumar, S.; Kumar, N.

2018-05-01

Here, we examined ionic current behavior of conical nanopores at different pH and a fixed ion concentration of potassium halide (KCl). Conical shaped nanopores have been developed by chemical etching technique in polyethylene terephthalate (PET) membrane/foil of thickness 12 micron. For this we employed a self-assembled electrochemical cell having two chambers and the foil was fitted in the centre of cell. The nanopores were produced in the foil using etching and stopping solutions. The experimental results show that ionic current rectification (ICR) occurs through synthesized conical nanopores. Further, ion current increases significantly with increase of voltage from the base side of nanopores to the tip side at fixed pH of electrolyte.

Negative differential electrolyte resistance in a solid-state nanopore resulting from electroosmotic flow bistability.

PubMed

Luo, Long; Holden, Deric A; White, Henry S

2014-03-25

A solid-state nanopore separating two aqueous solutions containing different concentrations of KCl is demonstrated to exhibit negative differential resistance (NDR) when a constant pressure is applied across the nanopore. NDR refers to a decrease in electrical current when the voltage applied across the nanopore is increased. NDR results from the interdependence of solution flow (electroosmotic and pressure-engendered) with the distributions of K+ and Cl- within the nanopore. A switch from a high-conductivity state to a low-conductivity state occurs over a very narrow voltage window (<2 mV) that depends on the nanopore geometry, electrolyte concentration, and nanopore surface charge density. Finite element simulations based on a simultaneous solution of the Navier-Stokes, Poisson, and Nernst-Planck equations demonstrate that NDR results from a positive feedback mechanism between the ion distributions and electroosmotic flow, yielding a true bistability in fluid flow and electrical current at a critical applied voltage, i.e., the NDR "switching potential". Solution pH and Ca2+ were separately employed as chemical stimuli to investigate the dependence of the NDR on the surface charge density. The NDR switching potential is remarkably sensitive to the surface charge density, and thus to pH and the presence of Ca2+, suggesting possible applications in chemical sensing.

Biomimetic glass nanopores employing aptamer gates responsive to a small molecule†

PubMed Central

Abelow, Alexis E.; Schepelina, Olga; White, Ryan J.; Vallée-Bélisle, Alexis

2011-01-01

We report the preparation of 20 and 65 nm radii glass nanopores whose surface is modified with DNA aptamers controlling the molecular transport through the nanopores in response to small molecule binding. PMID:20865192

Engineering the internal surfaces of three-dimensional nanoporous catalysts by surfactant-modified dealloying.

PubMed

Wang, Zhili; Liu, Pan; Han, Jiuhui; Cheng, Chun; Ning, Shoucong; Hirata, Akihiko; Fujita, Takeshi; Chen, Mingwei

2017-10-20

Tuning surface structures by bottom-up synthesis has been demonstrated as an effective strategy to improve the catalytic performances of nanoparticle catalysts. Nevertheless, the surface modification of three-dimensional nanoporous metals, fabricated by a top-down dealloying approach, has not been achieved despite great efforts devoted to improving the catalytic performance of three-dimensional nanoporous catalysts. Here we report a surfactant-modified dealloying method to tailor the surface structure of nanoporous gold for amplified electrocatalysis toward methanol oxidation and oxygen reduction reactions. With the assistance of surfactants, {111} or {100} faceted internal surfaces of nanoporous gold can be realized in a controllable manner by optimizing dealloying conditions. The surface modified nanoporous gold exhibits significantly enhanced electrocatalytic activities in comparison with conventional nanoporous gold. This study paves the way to develop high-performance three-dimensional nanoporous catalysts with a tunable surface structure by top-down dealloying for efficient chemical and electrochemical reactions.

Roles of Chemical Functionality and Pore Curvature in the Design of Nanoporous Proton Conductors

DOE PAGES

Jackson, Grayson L.; Perroni, Dominic V.; Mahanthappa, Mahesh K.

2017-10-03

Nanoporous proton-transporting media are critical components in fuel cells and other electrochemical devices, yet general molecular design criteria for new materials with enhanced performance remain obscure. Aqueous lyotropic liquid crystals (LLCs) comprise a platform for detailed studies of the molecular-level features governing proton transport in monodisperse, water-filled nanopores lined with well-defined chemical functionalities. Here, we report new alkylsulfonic acid LLCs that exhibit H+ conductivities as high as σ = 380 mS/cm at 80°C, which rival those of more acidic, perfluorinated polymers, thus demonstrating that the acidity of the pore functionality is not the sole determinant of proton transport. Direct experimentalmore » comparisons of LLCs with convex and concave nanopores of similar dimensions indicate that H+ conductivities therein sensitively depend on the hydration state of the acid functionalities and the pore curvature. These experiments suggest that judicious manipulation of pore curvature provides a new means for optimizing the activities of proton-exchange membranes and nanoporous solid acid catalysts.« less

Single Nanopore Investigations with Ion Conductance Microscopy

PubMed Central

Chen, Chiao-Chen; Zhou, Yi; Baker, Lane A.

2011-01-01

A three-electrode scanning ion conductance microscope (SICM) was used to investigate the local current-voltage properties of a single nanopore. In this experimental configuration, the response measured is a function of changes in the resistances involved in the pathways of ion migration. Single nanopore membranes utilized in this study were prepared with an epoxy painting procedure to isolate a single nanopore from a track-etch multi-pore membrane. Current-voltage responses measured with the SICM probe in the vicinity of a single nanopore were investigated in detail and agreed well with equivalent circuit models proposed in this study. With this modified SICM, the current-voltage responses characterized for the case of a single cylindrical pore and a single conical pore exhibit distinct conductance properties that originate from the geometry of nanopores. PMID:21923184

Effects of nanoporous anodic titanium oxide on human adipose derived stem cells.

PubMed

Malec, Katarzyna; Góralska, Joanna; Hubalewska-Mazgaj, Magdalena; Głowacz, Paulina; Jarosz, Magdalena; Brzewski, Pawel; Sulka, Grzegorz D; Jaskuła, Marian; Wybrańska, Iwona

The aim of current bone biomaterials research is to design implants that induce controlled, guided, successful, and rapid healing. Titanium implants are widely used in dental, orthopedic, and reconstructive surgery. A series of studies has indicated that cells can respond not only to the chemical properties of the biomaterial, but also, in particular, to the changes in surface topography. Nanoporous materials remain in focus of scientific queries due to their exclusive properties and broad applications. One such material is nanostructured titanium oxide with highly ordered, mutually perpendicular nanopores. Nanoporous anodic titanium dioxide (TiO 2 ) films were fabricated by a three-step anodization process in propan-1,2,3-triol-based electrolyte containing fluoride ions. Adipose-derived stem cells offer many interesting opportunities for regenerative medicine. The important goal of tissue engineering is to direct stem cell differentiation into a desired cell lineage. The influence of nanoporous TiO 2 with pore diameters of 80 and 108 nm on cell response, growth, viability, and ability to differentiate into osteoblastic lineage of human adipose-derived progenitors was explored. Cells were harvested from the subcutaneous abdominal fat tissue by a simple, minimally invasive, and inexpensive method. Our results indicate that anodic nanostructured TiO 2 is a safe and nontoxic biomaterial. In vitro studies demonstrated that the nanotopography induced and enhanced osteodifferentiation of human adipose-derived stem cells from the abdominal subcutaneous fat tissue.

Synthetic Design of Polysulfone Membranes: Morphological Effect on Property and Performance in Flow Batteries

NASA Astrophysics Data System (ADS)

Gindt, Brandon

This dissertation outlines a novel path towards improved understanding and function of proton exchange membranes (PEMs) for redox flow batteries, a large-scale battery storage device. This research uses synthetic methods and nanotechnology through two different approaches to prepare tailored polymer membranes: 1) Ion exchange membranes with enhanced chemical structures to promote membrane morphology on the nano-scale were prepared. Specifically, functional polysulfones (PSUs) were synthesized from different pre-sulfonated monomers. These PSUs have controlled placement and content of unique sulfonic acid moieties. PEMs were fabricated and characterized. The new PEMs showed desirable physical properties and performance in a vanadium redox flow battery (VRFB) cell. 2) Nanoporous PSU membranes were fabricated via post-hydrolysis of polylactide (PLA) from PLA-PSU-PLA triblock copolymer membranes. The controlled morphology and pore size of the resulting nanoporous membranes were evaluated by different microscopy and scattering techniques to understand structure-property relationships. Further, the resulting nanopore surface was chemically modified with sulfonic acid moieties. Membranes were analyzed and evaluated as separators for a VRFB. The chemically modified nanoporous PEMs exhibited unique behavior with respect to their ion conductivity when exposed to solutions of increasing acid concentration. In addition, the hierarchical micro-nanoporous membranes developed further showed promising structure and properties.

In vitro and in vivo evaluation of the inflammatory potential of various nanoporous hydroxyapatite biomaterials.

PubMed

Velard, Frédéric; Schlaubitz, Silke; Fricain, Jean-Christophe; Guillaume, Christine; Laurent-Maquin, Dominique; Möller-Siegert, Janina; Vidal, Loïc; Jallot, Edouard; Sayen, Stéphanie; Raissle, Olivier; Nedelec, Jean-Marie; Vix-Guterl, Cathie; Anselme, Karine; Amédée, Joëlle; Laquerrière, Patrice

2015-01-01

To discriminate the most important physicochemical parameters for bone reconstruction, the inflammatory potential of seven nanoporous hydroxyapatite powders synthesized by hard or soft templating was evaluated both in vitro and in vivo. After physical and chemical characterization of the powders, we studied the production of inflammatory mediators by human primary monocytes after 4 and 24 h in contact with powders, and the host response after 2 weeks implantation in a mouse critical size defect model. In vitro results highlighted increases in the secretion of TNF-α, IL-1, -8, -10 and proMMP-2 and -9 and decreases in the secretion of IL-6 only for powders prepared by hard templating. In vivo observations confirmed an extensive inflammatory tissue reaction and a strong resorption for the most inflammatory powder in vitro. These findings highlight that the most critical physicochemical parameters for these nanoporous hydroxyapatite are, the crystallinity that controls dissolution potential, the specific surface area and the size and shape of crystallites.

Hysteretic characteristics of 1/λ⁴ scattering of light during adsorption and desorption of water in porous Vycor glass with nanopores.

PubMed

Ogawa, Shigeo; Nakamura, Jiro

2013-10-01

Porous Vycor glass with nanopores is transparent in the visible region and is often used in colorimetric chemical sensing when impregnated with selectively reacting reagents. However, it has some disadvantages in sensing, since changes in the humidity of ambient air strongly affect its transmission. In this work, by combining a humidity-controlled thermostatic chamber and an ultraviolet-visible and near-infrared spectrophotometer through fiber optics, we analyzed the effect of increasing and decreasing humidity in the ambient air on the transparency change of the nanoporous glass. The transparency response in the visible region to changes in humidity is analyzed to correlate the turbidity response of the glass with the amount of water in it. The turbidity is found to be dependent on the inverse fourth power of the wavelength (1/λ⁴), which implies that Rayleigh-type scattering takes place for both adsorption and desorption of water. We show that measures of the extent of the optical inhomogeneity that causes the scattering, such as the effective radius of scatterers and their number density, exhibit a pronounced hysteretic characteristic for the imbibition and drainage of water, while the absorption inherent to imbibed water also shows another type of hysteresis that is quite similar to the sorption isotherms of water. On the basis of the above observations, we show that the transitory white turbidity of nanoporous glasses during changes in humidity can be consistently interpreted and quantitatively analyzed by a simple Rayleigh scattering mechanism.

Investigation of microcantilever array with ordered nanoporous coatings for selective chemical detection

NASA Astrophysics Data System (ADS)

Lee, J.-H.; Houk, R. T. J.; Robinson, A.; Greathouse, J. A.; Thornberg, S. M.; Allendorf, M. D.; Hesketh, P. J.

2010-04-01

In this paper we demonstrate the potential for novel nanoporous framework materials (NFM) such as metal-organic frameworks (MOFs) to provide selectivity and sensitivity to a broad range of analytes including explosives, nerve agents, and volatile organic compounds (VOCs). NFM are highly ordered, crystalline materials with considerable synthetic flexibility resulting from the presence of both organic and inorganic components within their structure. Detection of chemical weapons of mass destruction (CWMD), explosives, toxic industrial chemicals (TICs), and volatile organic compounds (VOCs) using micro-electro-mechanical-systems (MEMS) devices, such as microcantilevers and surface acoustic wave sensors, requires the use of recognition layers to impart selectivity. Traditional organic polymers are dense, impeding analyte uptake and slowing sensor response. The nanoporosity and ultrahigh surface areas of NFM enhance transport into and out of the NFM layer, improving response times, and their ordered structure enables structural tuning to impart selectivity. Here we describe experiments and modeling aimed at creating NFM layers tailored to the detection of water vapor, explosives, CWMD, and VOCs, and their integration with the surfaces of MEMS devices. Force field models show that a high degree of chemical selectivity is feasible. For example, using a suite of MOFs it should be possible to select for explosives vs. CWMD, VM vs. GA (nerve agents), and anthracene vs. naphthalene (VOCs). We will also demonstrate the integration of various NFM with the surfaces of MEMS devices and describe new synthetic methods developed to improve the quality of VFM coatings. Finally, MOF-coated MEMS devices show how temperature changes can be tuned to improve response times, selectivity, and sensitivity.

Nanoporous frameworks exhibiting multiple stimuli responsiveness

NASA Astrophysics Data System (ADS)

Kundu, Pintu K.; Olsen, Gregory L.; Kiss, Vladimir; Klajn, Rafal

2014-04-01

Nanoporous frameworks are polymeric materials built from rigid molecules, which give rise to their nanoporous structures with applications in gas sorption and storage, catalysis and others. Conceptually new applications could emerge, should these beneficial properties be manipulated by external stimuli in a reversible manner. One approach to render nanoporous frameworks responsive to external signals would be to immobilize molecular switches within their nanopores. Although the majority of molecular switches require conformational freedom to isomerize, and switching in the solid state is prohibited, the nanopores may provide enough room for the switches to efficiently isomerize. Here we describe two families of nanoporous materials incorporating the spiropyran molecular switch. These materials exhibit a variety of interesting properties, including reversible photochromism and acidochromism under solvent-free conditions, light-controlled capture and release of metal ions, as well reversible chromism induced by solvation/desolvation.

Synthesis and applications of nanoporous perovskite metal oxides

PubMed Central

Huang, Xiubing; Zhao, Guixia

2018-01-01

Perovskite-type metal oxides have been widely investigated and applied in various fields in the past several decades due to their extraordinary variability of compositions and structures with targeted physical and chemical properties (e.g., redox behaviour, oxygen mobility, electronic and ionic conductivity). Recently, nanoporous perovskite metal oxides have attracted extensive attention because of their special morphology and properties, as well as superior performance. This minireview aims at summarizing and reviewing the different synthesis methods of nanoporous perovskite metal oxides and their various applications comprehensively. The correlations between the nanoporous structures and the specific performance of perovskite oxides are summarized and highlighted. The future research directions of nanoporous perovskite metal oxides are also prospected. PMID:29862001

High performance SERS on nanoporous gold substrates synthesized by chemical de-alloying a Au-based metallic glass

NASA Astrophysics Data System (ADS)

Xue, Yanpeng; Scaglione, Federico; Rizzi, Paola; Battezzati, Livio

2017-12-01

A Au20Cu48Ag7Pd5Si20 metallic glass precursor has been used to synthesize nanoporous gold by chemical de-alloying in a mixture of HNO3 and HF. Gold ligaments of size ranging from 45 to 100 nm were obtained as a function of HNO3 concentration, electrolyte temperature and de-alloying time. The as-prepared nanoporous gold exhibited strong surface enhanced Raman scattering (SERS) effect using 4,4‧-bi-pyridine as probe molecule. For application in melamine sensing, the detection limit of 10-6 M was achieved, which indicated that this biocompatible material has great potential as SERS active substrate.

Solvothermal synthesis of nanoporous polymer chalk for painting superhydrophobic surfaces.

PubMed

Zhang, Yong-Lai; Wang, Jian-Nan; He, Yan; He, Yinyan; Xu, Bin-Bin; Wei, Shu; Xiao, Feng-Shou

2011-10-18

Reported here is a facile synthesis of nanoporous polymer chalk for painting superhydrophobic surfaces. Taking this nanoporous polymer as a media, superhydrophobicity is rapidly imparted onto three typical kinds of substrates, including paper, transparent polydimethylsiloxane (PDMS), and finger skin. Quantitative characterization showed that the adhesion between the water droplet and polymer-coated substrates decreased significantly compared to that on the original surface, further indicating the effective wetting mode transformation. The nanoporous polymer coating would open a new door for facile, rapid, safe, and larger scale fabrication of superhydrophobic surfaces on general substrates. © 2011 American Chemical Society

Engineering of Surface Chemistry for Enhanced Sensitivity in Nanoporous Interferometric Sensing Platforms.

PubMed

Law, Cheryl Suwen; Sylvia, Georgina M; Nemati, Madieh; Yu, Jingxian; Losic, Dusan; Abell, Andrew D; Santos, Abel

2017-03-15

We explore new approaches to engineering the surface chemistry of interferometric sensing platforms based on nanoporous anodic alumina (NAA) and reflectometric interference spectroscopy (RIfS). Two surface engineering strategies are presented, namely (i) selective chemical functionalization of the inner surface of NAA pores with amine-terminated thiol molecules and (ii) selective chemical functionalization of the top surface of NAA with dithiol molecules. The strong molecular interaction of Au 3+ ions with thiol-containing functional molecules of alkane chain or peptide character provides a model sensing system with which to assess the sensitivity of these NAA platforms by both molecular feature and surface engineering. Changes in the effective optical thickness of the functionalized NAA photonic films (i.e., sensing principle), in response to gold ions, are monitored in real-time by RIfS. 6-Amino-1-hexanethiol (inner surface) and 1,6-hexanedithiol (top surface), the most sensitive functional molecules from approaches i and ii, respectively, were combined into a third sensing strategy whereby the NAA platforms are functionalized on both the top and inner surfaces concurrently. Engineering of the surface according to this approach resulted in an additive enhancement in sensitivity of up to 5-fold compared to previously reported systems. This study advances the rational engineering of surface chemistry for interferometric sensing on nanoporous platforms with potential applications for real-time monitoring of multiple analytes in dynamic environments.

The role of nanopore shape in surface-induced crystallization

NASA Astrophysics Data System (ADS)

Diao, Ying; Harada, Takuya; Myerson, Allan S.; Alan Hatton, T.; Trout, Bernhardt L.

2011-11-01

Crystallization of a molecular liquid from solution often initiates at solid-liquid interfaces, and nucleation rates are generally believed to be enhanced by surface roughness. Here we show that, on a rough surface, the shape of surface nanopores can also alter nucleation kinetics. Using lithographic methods, we patterned polymer films with nanopores of various shapes and found that spherical nanopores 15-120 nm in diameter hindered nucleation of aspirin crystals, whereas angular nanopores of the same size promoted it. We also show that favourable surface-solute interactions are required for angular nanopores to promote nucleation, and propose that pore shape affects nucleation kinetics through the alteration of the orientational order of the crystallizing molecule near the angles of the pores. Our findings have clear technological implications, for instance in the control of pharmaceutical polymorphism and in the design of ‘seed’ particles for the regulation of crystallization of fine chemicals.

Atomic layer deposition of nanoporous biomaterials.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Narayan, R. J.; Adiga, S. P.; Pellin, M. J.

2010-03-01

Due to its chemical stability, uniform pore size, and high pore density, nanoporous alumina is being investigated for use in biosensing, drug delivery, hemodialysis, and other medical applications. In recent work, we have examined the use of atomic layer deposition for coating the surfaces of nanoporous alumina membranes. Zinc oxide coatings were deposited on nanoporous alumina membranes using atomic layer deposition. The zinc oxide-coated nanoporous alumina membranes demonstrated antimicrobial activity against Escherichia coli and Staphylococcus aureus bacteria. These results suggest that atomic layer deposition is an attractive technique for modifying the surfaces of nanoporous alumina membranes and other nanostructured biomaterials.more » Nanoporous alumina, also known as anodic aluminum oxide (AAO), is a nanomaterial that exhibits several unusual properties, including high pore densities, straight pores, small pore sizes, and uniform pore sizes. In 1953, Keller et al. showed that anodizing aluminum in acid electrolytes results in a thick layer of nearly cylindrical pores, which are arranged in a close-packed hexagonal cell structure. More recently, Matsuda & Fukuda demonstrated preparation of highly ordered platinum and gold nanohole arrays using a replication process. In this study, a negative structure of nanoporous alumina was initially fabricated and a positive structure of a nanoporous metal was subsequently fabricated. Over the past fifteen years, nanoporous alumina membranes have been used as templates for growth of a variety of nanostructured materials, including nanotubes, nanowires, nanorods, and nanoporous membranes.« less

Solid-State Nanopore.

PubMed

Yuan, Zhishan; Wang, Chengyong; Yi, Xin; Ni, Zhonghua; Chen, Yunfei; Li, Tie

2018-02-20

Solid-state nanopore has captured the attention of many researchers due to its characteristic of nanoscale. Now, different fabrication methods have been reported, which can be summarized into two broad categories: "top-down" etching technology and "bottom-up" shrinkage technology. Ion track etching method, mask etching method chemical solution etching method, and high-energy particle etching and shrinkage method are exhibited in this report. Besides, we also discussed applications of solid-state nanopore fabrication technology in DNA sequencing, protein detection, and energy conversion.

Solid-State Nanopore

NASA Astrophysics Data System (ADS)

Yuan, Zhishan; Wang, Chengyong; Yi, Xin; Ni, Zhonghua; Chen, Yunfei; Li, Tie

2018-02-01

Solid-state nanopore has captured the attention of many researchers due to its characteristic of nanoscale. Now, different fabrication methods have been reported, which can be summarized into two broad categories: "top-down" etching technology and "bottom-up" shrinkage technology. Ion track etching method, mask etching method chemical solution etching method, and high-energy particle etching and shrinkage method are exhibited in this report. Besides, we also discussed applications of solid-state nanopore fabrication technology in DNA sequencing, protein detection, and energy conversion.

Three-Dimensional Morphological and Chemical Evolution of Nanoporous Stainless Steel by Liquid Metal Dealloying [3D Morphological and Chemical Evolution of Nanoporous Stainless Steel by Liquid Metal Dealloying

DOE PAGES

Zhao, Chonghang; Wada, Takeshi; De Andrade, Vincent; ...

2017-09-04

Nanoporous materials, especially those fabricated by liquid metal dealloying processes, possess great potential in a wide range of applications due to their high surface area, bicontinuous structure with both open pores for transport and solid phase for conductivity or support, and low material cost. Here, we used X-ray nanotomography and X-ray fluorescence microscopy to reveal the three-dimensional (3D) morphology and elemental distribution within materials. Focusing on nanoporous stainless steel, we evaluated the 3D morphology of the dealloying front and established a quantitative processing-structure-property relationship at a later stage of dealloying. The morphological differences of samples created by liquid metal dealloyingmore » and aqueous dealloying methods were also discussed. Here, we concluded that it is particularly important to consider the dealloying, coarsening, and densification mechanisms in influencing the performance-determining, critical 3D parameters, such as tortuosity, pore size, porosity, curvature, and interfacial shape.« less

Three-Dimensional Morphological and Chemical Evolution of Nanoporous Stainless Steel by Liquid Metal Dealloying [3D Morphological and Chemical Evolution of Nanoporous Stainless Steel by Liquid Metal Dealloying

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Chonghang; Wada, Takeshi; De Andrade, Vincent

Nanoporous materials, especially those fabricated by liquid metal dealloying processes, possess great potential in a wide range of applications due to their high surface area, bicontinuous structure with both open pores for transport and solid phase for conductivity or support, and low material cost. Here, we used X-ray nanotomography and X-ray fluorescence microscopy to reveal the three-dimensional (3D) morphology and elemental distribution within materials. Focusing on nanoporous stainless steel, we evaluated the 3D morphology of the dealloying front and established a quantitative processing-structure-property relationship at a later stage of dealloying. The morphological differences of samples created by liquid metal dealloyingmore » and aqueous dealloying methods were also discussed. Here, we concluded that it is particularly important to consider the dealloying, coarsening, and densification mechanisms in influencing the performance-determining, critical 3D parameters, such as tortuosity, pore size, porosity, curvature, and interfacial shape.« less

Slow DNA Transport through Nanopores in Hafnium Oxide Membranes

PubMed Central

Bell, David C.; Cohen-Karni, Tzahi; Rosenstein, Jacob K.; Wanunu, Meni

2016-01-01

We present a study of double- and single-stranded DNA transport through nanopores fabricated in ultrathin (2–7 nm thick) free-standing hafnium oxide (HfO2) membranes. The high chemical stability of ultrathin HfO2 enables long-lived experiments with <2 nm diameter pores that last several hours, in which we observe >50 000 DNA translocations with no detectable pore expansion. Mean DNA velocities are slower than velocities through comparable silicon nitride pores, providing evidence that HfO2 nanopores have favorable physicochemical interactions with nucleic acids that can be leveraged to slow down DNA in a nanopore. PMID:24083444

Scan-rate-dependent current rectification of cone-shaped silica nanopores in quartz nanopipettes.

PubMed

Guerrette, Joshua P; Zhang, Bo

2010-12-08

Here we report the voltammetric behavior of cone-shaped silica nanopores in quartz nanopipettes in aqueous solutions as a function of the scan rate, v. Current rectification behavior for silica nanopores with diameters in the range 4-25 nm was studied. The rectification behavior was found to be strongly dependent on the scan rate. At low scan rates (e.g., v < 1 V/s), the rectification ratio was found to be at its maximum and relatively independent of v. At high scan rates (e.g., v > 200 V/s), a nearly linear current-voltage response was obtained. In addition, the initial voltage was shown to play a critical role in the current-voltage response of cone-shaped nanopores at high scan rates. We explain this v-dependent current-voltage response by ionic redistribution in the vicinity of the nanopore mouth.

Voltage-Rectified Current and Fluid Flow in Conical Nanopores.

PubMed

Lan, Wen-Jie; Edwards, Martin A; Luo, Long; Perera, Rukshan T; Wu, Xiaojian; Martin, Charles R; White, Henry S

2016-11-15

Ion current rectification (ICR) refers to the asymmetric potential-dependent rate of the passage of solution ions through a nanopore, giving rise to electrical current-voltage characteristics that mimic those of a solid-state electrical diode. Since the discovery of ICR in quartz nanopipettes two decades ago, synthetic nanopores and nanochannels of various geometries, fabricated in membranes and on wafers, have been extensively investigated to understand fundamental aspects of ion transport in highly confined geometries. It is now generally accepted that ICR requires an asymmetric electrical double layer within the nanopore, producing an accumulation or depletion of charge-carrying ions at opposite voltage polarities. Our research groups have recently explored how the voltage-dependent ion distributions and ICR within nanopores can induce novel nanoscale flow phenomena that have applications in understanding ionics in porous materials used in energy storage devices, chemical sensing, and low-cost electrical pumping of fluids. In this Account, we review our most recent investigations on this topic, based on experiments using conical nanopores (10-300 nm tip opening) fabricated in thin glass, mica, and polymer membranes. Measurable fluid flow in nanopores can be induced either using external pressure forces, electrically via electroosmotic forces, or by a combination of these two forces. We demonstrate that pressure-driven flow can greatly alter the electrical properties of nanopores and, vice versa, that the nonlinear electrical properties of conical nanopores can impart novel and useful flow phenomena. Electroosmotic flow (EOF), which depends on the magnitude of the ion fluxes within the double layer of the nanopore, is strongly coupled to the accumulation/depletion of ions. Thus, the same underlying cause of ICR also leads to EOF rectification, i.e., unequal flows occurring for the same voltage but opposite polarities. EOF rectification can be used to electrically pump fluids with very precise control across membranes containing conical pores via the application of a symmetric sinusoidal voltage. The combination of pressure and asymmetric EOF can also provide a means to generate new nanopore electrical behaviors, including negative differential resistance (NDR), in which the current through a conical pore decreases with increasing driving force (applied voltage), similar to solid-state tunnel diodes. NDR results from a positive feedback mechanism between the ion distributions and EOF, yielding a true bistability in both fluid flow and electrical current at a critical applied voltage. Nanopore-based NDR is extremely sensitive to the surface charge near the nanopore opening, suggesting possible applications in chemical sensing.

Selective Separation of Metal Ions via Monolayer Nanoporous Graphene with Carboxyl Groups.

PubMed

Li, Zhan; Liu, Yanqi; Zhao, Yang; Zhang, Xin; Qian, Lijuan; Tian, Longlong; Bai, Jing; Qi, Wei; Yao, Huijun; Gao, Bin; Liu, Jie; Wu, Wangsuo; Qiu, Hongdeng

2016-10-18

Graphene-coated plastic substrates, such as polyethylene terephthalate (PET), are regularly used in flexible electronic devices. Here we demonstrate a new application of the graphene-coated nanoporous PET membrane for the selective separation of metal ions in an ion exchange manner. Irradiation with swift heavy ions is used to perforate graphene and PET substrate. This process could create graphene nanopores with carboxyl groups, thus forming conical holes in the PET after chemical etching to support graphene nanopores. Therefore, a monolayer nanoporous graphene membrane with a PET substrate is constructed successfully to investigate its ionic selective separation. We find that the permeation ratio of ions strongly depends on the temperature and H + concentration in the driving solution. An electric field can increase the permeation ratio of ions through the graphene nanopores, but it inhibits the ion selective separation. Moreover, the structure of the graphene nanopore with carboxyl groups is resolved at the density functional theory level. The results show the asymmetric structure of the nanopore with carboxyl groups, and the analysis indicates that the ionic permeation can be attributed to the ion exchange between metal ions and protons on the two sides of graphene nanopores. These results would be beneficial to the design of membrane separation materials made from graphene with efficient online and offline bulk separation.

Length-dependent corrosion behavior, Ni2+ release, cytocompatibility, and antibacterial ability of Ni-Ti-O nanopores anodically grown on biomedical NiTi alloy.

PubMed

Hang, Ruiqiang; Liu, Yanlian; Bai, Long; Zhang, Xiangyu; Huang, Xiaobo; Jia, Husheng; Tang, Bin

2018-08-01

In the present work, nickel-titanium-oxygen nanopores with different length (0.55-114 μm) were anodically grown on nearly equiatomic nickel-titanium (NiTi) alloy. Length-dependent corrosion behavior, nickel ion (Ni 2+ ) release, cytocompatibility, and antibacterial ability were investigated by electrochemical, analytical chemistry, and biological methods. The results show constructing nanoporous structure on the NiTi alloy improve its corrosion resistance. However, the anodized samples release more Ni 2+ than that of the bare NiTi alloy, suggesting chemical dissolution of the nanopores rather than electrochemical corrosion governs the Ni 2+ release. In addition, the Ni 2+ release amount increases with nanopore length. The anodized samples show good cytocompatibility when the nanopore length is <11 μm. Encouragingly, the length scale covers the one (1-11 μm) that the nanopores showing favorable antibacterial ability. Consequently, the nanopores with length in the range of 1-11 μm are promising as coatings of biomedical NiTi alloy for anti-infection, drug delivery, and other desirable applications. Copyright © 2018 Elsevier B.V. All rights reserved.

Facile fabrication of nanofluidic diode membranes using anodic aluminium oxide

NASA Astrophysics Data System (ADS)

Wu, Songmei; Wildhaber, Fabien; Vazquez-Mena, Oscar; Bertsch, Arnaud; Brugger, Juergen; Renaud, Philippe

2012-08-01

Active control of ion transport plays important roles in chemical and biological analytical processes. Nanofluidic systems hold the promise for such control through electrostatic interaction between ions and channel surfaces. Most existing experiments rely on planar geometry where the nanochannels are generally very long and shallow with large aspect ratios. Based on this configuration the concepts of nanofluidic gating and rectification have been successfully demonstrated. However, device minimization and throughput scaling remain significant challenges. We report here an innovative and facile realization of hetero-structured Al2O3/SiO2 (Si) nanopore array membranes by using pattern transfer of self-organized nanopore structures of anodic aluminum oxide (AAO). Thanks to the opposite surface charge states of Al2O3 (positive) and SiO2 (negative), the membrane exhibits clear rectification of ion current in electrolyte solutions with very low aspect ratios compared to previous approaches. Our hetero-structured nanopore arrays provide a valuable platform for high throughput applications such as molecular separation, chemical processors and energy conversion.Active control of ion transport plays important roles in chemical and biological analytical processes. Nanofluidic systems hold the promise for such control through electrostatic interaction between ions and channel surfaces. Most existing experiments rely on planar geometry where the nanochannels are generally very long and shallow with large aspect ratios. Based on this configuration the concepts of nanofluidic gating and rectification have been successfully demonstrated. However, device minimization and throughput scaling remain significant challenges. We report here an innovative and facile realization of hetero-structured Al2O3/SiO2 (Si) nanopore array membranes by using pattern transfer of self-organized nanopore structures of anodic aluminum oxide (AAO). Thanks to the opposite surface charge states of Al2O3 (positive) and SiO2 (negative), the membrane exhibits clear rectification of ion current in electrolyte solutions with very low aspect ratios compared to previous approaches. Our hetero-structured nanopore arrays provide a valuable platform for high throughput applications such as molecular separation, chemical processors and energy conversion. Electronic supplementary information (ESI) available: Pattern transfer of local AAO mask into Si layers of different thickness; characterization of the Ag/AgCl electrodes and the cell constant; control experiments of mono-charged nanopore membranes; and simulation of ionic transport in nanofluidic diodes. See DOI: 10.1039/c2nr31243c

Highly Sensitive Biosensing with Solid-State Nanopores Displaying Enzymatically Reconfigurable Rectification Properties.

PubMed

Pérez-Mitta, Gonzalo; Peinetti, Ana S; Cortez, M Lorena; Toimil-Molares, María Eugenia; Trautmann, Christina; Azzaroni, Omar

2018-05-09

Molecular design of biosensors based on enzymatic processes taking place in nanofluidic elements is receiving increasing attention by the scientific community. In this work, we describe the construction of novel ultrasensitive enzymatic nanopore biosensors employing "reactive signal amplifiers" as key elements coupled to the transduction mechanism. The proposed framework offers innovative design concepts not only to amplify the detected ionic signal and develop ultrasensitive nanopore-based sensors but also to construct nanofluidic diodes displaying specific chemo-reversible rectification properties. The integrated approach is demonstrated by electrostatically assembling poly(allylamine) on the anionic pore walls followed by the assembly of urease. We show that the cationic weak polyelectrolyte acts as a "reactive signal amplifier" in the presence of local pH changes induced by the enzymatic reaction. These bioinduced variations in proton concentration ultimately alter the protonation degree of the polyamine resulting in amplifiable, controlled, and reproducible changes in the surface charge of the pore walls, and consequently on the generated ionic signals. The "iontronic" response of the as-obtained devices is fully reversible, and nanopores are reused and assayed with different urea concentrations, thus ensuring reliable design. The limit of detection (LOD) was 1 nM. To the best of our knowledge, this value is the lowest LOD reported to date for enzymatic urea detection. In this context, we envision that this approach based on the use of "reactive signal amplifiers" into solid-state nanochannels will provide new alternatives for the molecular design of highly sensitive nanopore biosensors as well as (bio)chemically addressable nanofluidic elements.

Engineering of highly ordered TiO2 nanopore arrays by anodization

NASA Astrophysics Data System (ADS)

Wang, Huijie; Huang, Zhennan; Zhang, Li; Ding, Jie; Ma, Zhaoxia; Liu, Yong; Kou, Shengzhong; Yang, Hangsheng

2016-07-01

Finite element analysis was used to simulate the current density distributions in the TiO2 barrier layer formed at the initial stage of Ti anodization. The morphology modification of the barrier layer was found to induce current density distribution change. By starting the anodization with proper TiO2 barrier layer morphology, the current density distribution can be adjusted to favor the formation of either nanotube arrays or nanopore arrays of anodic TiO2. We also found that the addition of sodium acetate into the electrolyte suppressed both the field-assisted chemical dissolution of TiO2 and the TiF62- hydrolysis induced TiO2 deposition during anodization, and thus further favored the nanopore formation. Accordingly, highly ordered anodic TiO2 nanopore arrays, similar to anodic aluminum oxide nanopore arrays, were successfully prepared.

Towards efficient chemical synthesis via engineering enzyme catalysis in biomimetic nanoreactors.

PubMed

Liu, Jia; Yang, Qihua; Li, Can

2015-09-18

Biocatalysis with immobilized enzymes as catalysts holds enormous promise in developing more efficient and sustainable processes for the synthesis of fine chemicals, chiral pharmaceuticals and biomass feedstocks. Despite the appealing potentials, nowadays the industrial-scale application of biocatalysts is still quite modest in comparison with that of traditional chemical catalysts. A critical issue is that the catalytic performance of enzymes, the sophisticated and vulnerable catalytic machineries, strongly depends on their intracellular working environment; however the working circumstances provided by the support matrix are radically different from those in cells. This often leads to various adverse consequences on enzyme conformation and dynamic properties, consequently decreasing the overall performance of immobilized enzymes with regard to their activity, selectivity and stability. Engineering enzyme catalysis in support nanopores by mimicking the physiological milieu of enzymes in vivo and investigating how the interior microenvironment of nanopores imposes an influence on enzyme behaviors in vitro are of paramount significance to modify and improve the catalytic functions of immobilized enzymes. In this feature article, we have summarized the recent advances in mimicking the working environment and working patterns of intracellular enzymes in nanopores of mesoporous silica-based supports. Especially, we have demonstrated that incorporation of polymers into silica nanopores could be a valuable approach to create the biomimetic microenvironment for enzymes in the immobilized state.

Building membrane nanopores

NASA Astrophysics Data System (ADS)

Howorka, Stefan

2017-07-01

Membrane nanopores--hollow nanoscale barrels that puncture biological or synthetic membranes--have become powerful tools in chemical- and biosensing, and have achieved notable success in portable DNA sequencing. The pores can be self-assembled from a variety of materials, including proteins, peptides, synthetic organic compounds and, more recently, DNA. But which building material is best for which application, and what is the relationship between pore structure and function? In this Review, I critically compare the characteristics of the different building materials, and explore the influence of the building material on pore structure, dynamics and function. I also discuss the future challenges of developing nanopore technology, and consider what the next-generation of nanopore structures could be and where further practical applications might emerge.

Pulsed plasma polymerization for controlling shrinkage and surface composition of nanopores

NASA Astrophysics Data System (ADS)

Asghar, Waseem; Ilyas, Azhar; Deshmukh, Rajendra R.; Sumitsawan, Sulak; Timmons, Richard B.; Iqbal, Samir M.

2011-07-01

Solid-state nanopores have emerged as sensors for single molecules and these have been employed to examine the biophysical properties of an increasingly large variety of biomolecules. Herein we describe a novel and facile approach to precisely adjust the pore size, while simultaneously controlling the surface chemical composition of the solid-state nanopores. Specifically, nanopores fabricated using standard ion beam technology are shrunk to the requisite molecular dimensions via the deposition of highly conformal pulsed plasma generated thin polymeric films. The plasma treatment process provides accurate control of the pore size as the conformal film deposition depends linearly on the deposition time. Simultaneously, the pore and channel chemical compositions are controlled by appropriate selection of the gaseous monomer and plasma conditions employed in the deposition of the polymer films. The controlled pore shrinkage is characterized with high resolution AFM, and the film chemistry of the plasma generated polymers is analyzed with FTIR and XPS. The stability and practical utility of this new approach is demonstrated by successful single molecule sensing of double-stranded DNA. The process offers a viable new advance in the fabrication of tailored nanopores, in terms of both the pore size and surface composition, for usage in a wide range of emerging applications.

Single molecule transistor based nanopore for the detection of nicotine

NASA Astrophysics Data System (ADS)

Ray, S. J.

2014-12-01

A nanopore based detection methodology was proposed and investigated for the detection of Nicotine. This technique uses a Single Molecular Transistor working as a nanopore operational in the Coulomb Blockade regime. When the Nicotine molecule is pulled through the nanopore area surrounded by the Source(S), Drain (D), and Gate electrodes, the charge stability diagram can detect the presence of the molecule and is unique for a specific molecular structure. Due to the weak coupling between the different electrodes which is set by the nanopore size, the molecular energy states stay almost unaffected by the electrostatic environment that can be realised from the charge stability diagram. Identification of different orientation and position of the Nicotine molecule within the nanopore area can be made from specific regions of overlap between different charge states on the stability diagram that could be used as an electronic fingerprint for detection. This method could be advantageous and useful to detect the presence of Nicotine in smoke which is usually performed using chemical chromatography techniques.

Integrated nanopore sensing platform with sub-microsecond temporal resolution

PubMed Central

Rosenstein, Jacob K; Wanunu, Meni; Merchant, Christopher A; Drndic, Marija; Shepard, Kenneth L

2012-01-01

Nanopore sensors have attracted considerable interest for high-throughput sensing of individual nucleic acids and proteins without the need for chemical labels or complex optics. A prevailing problem in nanopore applications is that the transport kinetics of single biomolecules are often faster than the measurement time resolution. Methods to slow down biomolecular transport can be troublesome and are at odds with the natural goal of high-throughput sensing. Here we introduce a low-noise measurement platform that integrates a complementary metal-oxide semiconductor (CMOS) preamplifier with solid-state nanopores in thin silicon nitride membranes. With this platform we achieved a signal-to-noise ratio exceeding five at a bandwidth of 1 MHz, which to our knowledge is the highest bandwidth nanopore recording to date. We demonstrate transient signals as brief as 1 μs from short DNA molecules as well as current signatures during molecular passage events that shed light on submolecular DNA configurations in small nanopores. PMID:22426489

Eco-friendly synthesis for MCM-41 nanoporous materials using the non-reacted reagents in mother liquor.

PubMed

Ng, Eng-Poh; Goh, Jia-Yi; Ling, Tau Chuan; Mukti, Rino R

2013-03-04

Nanoporous materials such as Mobil composite material number 41 (MCM-41) are attractive for applications such as catalysis, adsorption, supports, and carriers. Green synthesis of MCM-41 is particularly appealing because the chemical reagents are useful and valuable. We report on the eco-friendly synthesis of MCM-41 nanoporous materials via multi-cycle approach by re-using the non-reacted reagents in supernatant as mother liquor after separating the solid product. This approach was achieved via minimal requirement of chemical compensation where additional fresh reactants were added into the mother liquor followed by pH adjustment after each cycle of synthesis. The solid product of each successive batch was collected and characterized while the non-reacted reagents in supernatant can be recovered and re-used to produce subsequent cycle of MCM-41. The multi-cycle synthesis is demonstrated up to three times in this research. This approach suggests a low cost and eco-friendly synthesis of nanoporous material since less waste is discarded after the product has been collected, and in addition, product yield can be maintained at the high level.

Eco-friendly synthesis for MCM-41 nanoporous materials using the non-reacted reagents in mother liquor

PubMed Central

2013-01-01

Nanoporous materials such as Mobil composite material number 41 (MCM-41) are attractive for applications such as catalysis, adsorption, supports, and carriers. Green synthesis of MCM-41 is particularly appealing because the chemical reagents are useful and valuable. We report on the eco-friendly synthesis of MCM-41 nanoporous materials via multi-cycle approach by re-using the non-reacted reagents in supernatant as mother liquor after separating the solid product. This approach was achieved via minimal requirement of chemical compensation where additional fresh reactants were added into the mother liquor followed by pH adjustment after each cycle of synthesis. The solid product of each successive batch was collected and characterized while the non-reacted reagents in supernatant can be recovered and re-used to produce subsequent cycle of MCM-41. The multi-cycle synthesis is demonstrated up to three times in this research. This approach suggests a low cost and eco-friendly synthesis of nanoporous material since less waste is discarded after the product has been collected, and in addition, product yield can be maintained at the high level. PMID:23497184

Synthesis of Hierarchical Nanoporous Microstructures via the Kirkendall Effect in Chemical Reduction Process

NASA Astrophysics Data System (ADS)

Gao, Ling; Pang, Chao; He, Dafang; Shen, Liming; Gupta, Arunava; Bao, Ningzhong

2015-11-01

A series of novel hierarchical nanoporous microstructures have been synthesized through one-step chemical reduction of micron size Cu2O and Co3O4 particles. By controlling the reduction time, non-porous Cu2O microcubes sequentially transform to nanoporous Cu/Cu2O/Cu dented cubic composites and hollow eightling-like Cu microparticles. The mechanism involved in the complex structural evolution is explained based on oxygen diffusion and Kirkendall effect. The nanoporous Cu/Cu2O/Cu dented cubic composites exhibit superior electrochemical performance as compared to solid Cu2O microcubes. The reduction of nonporous Co3O4 also exhibits a uniform sequential reduction process from nonporous Co3O4 to porous Co3O4/CoO composites, porous CoO, porous CoO/Co composites, and porous foam-like Co particles. Nanoscale channels originate from the particle surface and eventually develop inside the entire product, resulting in porous foam-like Co microparticles. The Kirkendall effect is believed to facilitate the formation of porous structures in both processes.

Understanding Radionuclide Interactions with Layered Materials

NASA Astrophysics Data System (ADS)

Wang, Y.

2015-12-01

Layered materials play an important role in nuclear waste management and environmental cleanup. Better understanding of radionuclide interactions with those materials is critical for engineering high-performance materials for various applications. This presentation will provide an overview on radionuclide interactions with two general categories of layered materials - cationic clays and anionic clays - from a perspective of nanopore confinement. Nanopores are widely present in layered materials, either as the interlayers or as inter-particle space. Nanopore confinement can significantly modify chemical reactions in those materials. This effect may cause the preferential enrichment of radionuclides in nanopores and therefore directly impact the mobility of the radionuclides. This effect also implies that conventional sorption measurements using disaggregated samples may not represent chemical conditions in actual systems. The control of material structures on ion exchange, surface complexation, and diffusion in layered materials will be systematically examined, and the related modeling approaches will be discussed. This work was performed at Sandia National Laboratories, which is a multiprogram laboratory operated by Sandia Corporation, a Lockheed-Martin Company, for the DOE under contract DE-AC04-94AL8500.

Eco-friendly synthesis for MCM-41 nanoporous materials using the non-reacted reagents in mother liquor

NASA Astrophysics Data System (ADS)

Ng, Eng-Poh; Goh, Jia-Yi; Ling, Tau Chuan; Mukti, Rino R.

2013-03-01

Nanoporous materials such as Mobil composite material number 41 (MCM-41) are attractive for applications such as catalysis, adsorption, supports, and carriers. Green synthesis of MCM-41 is particularly appealing because the chemical reagents are useful and valuable. We report on the eco-friendly synthesis of MCM-41 nanoporous materials via multi-cycle approach by re-using the non-reacted reagents in supernatant as mother liquor after separating the solid product. This approach was achieved via minimal requirement of chemical compensation where additional fresh reactants were added into the mother liquor followed by pH adjustment after each cycle of synthesis. The solid product of each successive batch was collected and characterized while the non-reacted reagents in supernatant can be recovered and re-used to produce subsequent cycle of MCM-41. The multi-cycle synthesis is demonstrated up to three times in this research. This approach suggests a low cost and eco-friendly synthesis of nanoporous material since less waste is discarded after the product has been collected, and in addition, product yield can be maintained at the high level.

Single Nanoparticle Translocation Through Chemically Modified Solid Nanopore

NASA Astrophysics Data System (ADS)

Tan, Shengwei; Wang, Lei; Liu, Hang; Wu, Hongwen; Liu, Quanjun

2016-02-01

The nanopore sensor as a high-throughput and low-cost technology can detect single nanoparticle in solution. In the present study, the silicon nitride nanopores were fabricated by focused Ga ion beam (FIB), and the surface was functionalized with 3-aminopropyltriethoxysilane to change its surface charge density. The positively charged nanopore surface attracted negatively charged nanoparticles when they were in the vicinity of the nanopore. And, nanoparticle translocation speed was slowed down to obtain a clear and deterministic signal. Compared with previous studied small nanoparticles, the electrophoretic translocation of negatively charged polystyrene (PS) nanoparticles (diameter ~100 nm) was investigated in solution using the Coulter counter principle in which the time-dependent nanopore current was recorded as the nanoparticles were driven across the nanopore. A linear dependence was found between current drop and biased voltage. An exponentially decaying function ( t d ~ e -v/v0 ) was found between the duration time and biased voltage. The interaction between the amine-functionalized nanopore wall and PS microspheres was discussed while translating PS microspheres. We explored also translocations of PS microspheres through amine-functionalized solid-state nanopores by varying the solution pH (5.4, 7.0, and 10.0) with 0.02 M potassium chloride (KCl). Surface functionalization showed to provide a useful step to fine-tune the surface property, which can selectively transport molecules or particles. This approach is likely to be applied to gene sequencing.

Molecular simulations for energy, environmental and pharmaceutical applications of nanoporous materials: from zeolites, metal-organic frameworks to protein crystals.

PubMed

Jiang, Jianwen; Babarao, Ravichandar; Hu, Zhongqiao

2011-07-01

Nanoporous materials have widespread applications in chemical industry, but the pathway from laboratory synthesis and testing to practical utilization of nanoporous materials is substantially challenging and requires fundamental understanding from the bottom up. With ever-growing computational resources, molecular simulations have become an indispensable tool for material characterization, screening and design. This tutorial review summarizes the recent simulation studies in zeolites, metal-organic frameworks and protein crystals, and provides a molecular overview for energy, environmental and pharmaceutical applications of nanoporous materials with increasing degree of complexity in building blocks. It is demonstrated that molecular-level studies can bridge the gap between physical and engineering sciences, unravel microscopic insights that are otherwise experimentally inaccessible, and assist in the rational design of new materials. The review is concluded with major challenges in future simulation exploration of novel nanoporous materials for emerging applications.

Enhanced translocation of single DNA molecules through α-hemolysin nanopores by manipulation of internal charge

PubMed Central

Maglia, Giovanni; Restrepo, Marcela Rincon; Mikhailova, Ellina; Bayley, Hagan

2008-01-01

Both protein and solid-state nanopores are under intense investigation for the analysis of nucleic acids. A crucial advantage of protein nanopores is that site-directed mutagenesis permits precise tuning of their properties. Here, by augmenting the internal positive charge within the α-hemolysin pore and varying its distribution, we increase the frequency of translocation of a 92-nt single-stranded DNA through the pore at +120 mV by ≈10-fold over the wild-type protein and dramatically lower the voltage threshold at which translocation occurs, e.g., by 50 mV for 1 event·s−1·μM−1. Further, events in which DNA enters the pore, but is not immediately translocated, are almost eliminated. These experiments provide a basis for improved nucleic acid analysis with protein nanopores, which might be translated to solid-state nanopores by using chemical surface modification. PMID:19060213

Electrochemistry at Edge of Single Graphene Layer in a Nanopore

PubMed Central

Banerjee, Shouvik; Shim, Jiwook; Rivera, Jose; Jin, Xiaozhong; Estrada, David; Solovyeva, Vita; You, Xiuque; Pak, James; Pop, Eric; Aluru, Narayana; Bashir, Rashid

2013-01-01

We study the electrochemistry of single layer graphene edges using a nanopore-based structure consisting of stacked graphene and Al2O3 dielectric layers. Nanopores, with diameters ranging from 5 to 20 nm, are formed by an electron beam sculpting process on the stacked layers. This leads to unique edge structure which, along with the atomically thin nature of the embedded graphene electrode, demonstrates electrochemical current densities as high as 1.2 × 104 A/cm2. The graphene edge embedded structure offers a unique capability to study the electrochemical exchange at an individual graphene edge, isolated from the basal plane electrochemical activity. We also report ionic current modulation in the nanopore by biasing the embedded graphene terminal with respect to the electrodes in the fluid. The high electrochemical specific current density for a graphene nanopore-based device can have many applications in sensitive chemical and biological sensing, and energy storage devices. PMID:23249127

Nanoporous Au: An experimental study on the porosity of dealloyed AuAg leafs

NASA Astrophysics Data System (ADS)

Grillo, R.; Torrisi, V.; Ruffino, F.

2016-12-01

We present a study on the fraction of porosity for dealloyed nanoporous Au leafs. Nanoporous Au is attracting great scientific interest due to its peculiar plasmonic properties and the high exposed surface (∼10 m2/g). As examples, it was used in prototypes of chemical and biological devices. However, the maximization of the devices sensitivity is subjected to the maximization of the exposed surface by the nanoporous Au, i. e. maximization of the porosity fraction. So, we report on the analyses of the porosity fraction in nanoporous Au leafs as a function of the fabrication process parameters. We dealloyed 60 μm-thick Au23Ag77 at.% leafs and we show that: a) for dealloying time till to 6 h, only a 450 nm-thick surface layer of the leafs assumes a nanoporous structure with a porosity fraction of 32%. For a dealloying time of 20 h the leafs result fragmented in small black pieces with a porosity fraction increased to 60%. b) After 600 °C-30 minutes annealing of the previous samples, the nanopores disappear due to the Au/residual Ag inter-diffusion. c) After a second dealloying process on the previously annealed samples, the surface nanoporous structure is, again, obtained with the porosity fraction increased to 50%.

Stimuli-Responsive Polymer Brushes for Flow Control through Nanopores

PubMed Central

Adiga, Shashishekar P.; Brenner, Donald W.

2012-01-01

Responsive polymers attached to the inside of nano/micro-pores have attracted great interest owing to the prospect of designing flow-control devices and signal responsive delivery systems. An intriguing possibility involves functionalizing nanoporous materials with smart polymers to modulate biomolecular transport in response to pH, temperature, ionic concentration, light or electric field. These efforts open up avenues to develop smart medical devices that respond to specific physiological conditions. In this work, an overview of nanoporous materials functionalized with responsive polymers is given. Various examples of pH, temperature and solvent responsive polymers are discussed. A theoretical treatment that accounts for polymer conformational change in response to a stimulus and the associated flow-control effect is presented. PMID:24955529

A reference electrode based on polyvinyl butyral (PVB) polymer for decentralized chemical measurements.

PubMed

Guinovart, Tomàs; Crespo, Gastón A; Rius, F Xavier; Andrade, Francisco J

2014-04-22

A new solid-state reference electrode using a polymeric membrane of polyvinyl butyral (PVB), Ag/AgCl and NaCl to be used in decentralized chemical measurements is presented. The electrode is made by drop-casting the membrane cocktail onto a glassy carbon (GC) substrate. A stable potential (less than 1 mV dec(-1)) over a wide range of concentrations for the several chemical species tested is obtained. No significant influence to changes in redox potential, light and pH are observed. The response of this novel electrode shows good correlation when compared with a conventional double-junction reference electrode. Also good long-term stability (90±33 μV/h) and a lifetime of approximately 4 months are obtained. Aspects related to the working mechanisms are discussed. Atomic Force Microscopy (AFM) studies reveal the presence of nanopores and channels on the surface, and electrochemical impedance spectroscopy (EIS) of optimized electrodes show low bulk resistances, usually in the kΩ range, suggesting that a nanoporous polymeric structure is formed in the interface with the solution. Future applications of this electrode as a disposable device for decentralized measurements are discussed. Examples of the utilization on wearable substrates (tattoos, fabrics, etc) are provided. Copyright © 2014 Elsevier B.V. All rights reserved.

Detecting trihalomethanes using nanoporous-carbon coated surface-acoustic-wave sensors

DOE PAGES

Siegal, Michael P.; Mowry, Curtis D.; Pfeifer, Kent B.; ...

2015-03-07

We study nanoporous-carbon (NPC) grown via pulsed laser deposition (PLD) as a sorbent coating on 96.5-MHz surface-acoustic-wave (SAW) devices to detect trihalomethanes (THMs), regulated byproducts from the chemical treatment of drinking water. Using both insertion-loss and isothermal-response measurements from known quantities of chloroform, the highest vapor pressure THM, we optimize the NPC mass-density at 1.05 ± 0.08 g/cm3 by controlling the background argon pressure during PLD. Precise THM quantities in a chlorobenzene solvent are directly injected into a separation column and detected as the phase-angle shift of the SAW device output compared to the drive signal. Using optimized NPC-coated SAWs,more » we study the chloroform response as a function of operating temperatures ranging from 10–50°C. Finally, we demonstrate individual responses from complex mixtures of all four THMs, with masses ranging from 10–2000 ng, after gas chromatography separation. As a result, estimates for each THM detection limit using a simple peak-height response evaluation are 4.4 ng for chloroform and 1 ng for bromoform; using an integrated-peak area response analysis improves the detection limits to 0.73 ng for chloroform and 0.003 ng bromoform.« less

Single molecule transistor based nanopore for the detection of nicotine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ray, S. J., E-mail: ray.sjr@gmail.com

A nanopore based detection methodology was proposed and investigated for the detection of Nicotine. This technique uses a Single Molecular Transistor working as a nanopore operational in the Coulomb Blockade regime. When the Nicotine molecule is pulled through the nanopore area surrounded by the Source(S), Drain (D), and Gate electrodes, the charge stability diagram can detect the presence of the molecule and is unique for a specific molecular structure. Due to the weak coupling between the different electrodes which is set by the nanopore size, the molecular energy states stay almost unaffected by the electrostatic environment that can be realisedmore » from the charge stability diagram. Identification of different orientation and position of the Nicotine molecule within the nanopore area can be made from specific regions of overlap between different charge states on the stability diagram that could be used as an electronic fingerprint for detection. This method could be advantageous and useful to detect the presence of Nicotine in smoke which is usually performed using chemical chromatography techniques.« less

Molecular Simulation Evaluation of Macromolecular Transport through Nanofiltration Membranes

NASA Astrophysics Data System (ADS)

Almodovar Arbelo, Noelia; Boudouris, Bryan; Corti, David

A hybrid Monte Carlo and Molecular Dynamics simulation technique was implemented to elucidate the equilibrium behavior and transport properties of a model macromolecule as it navigated across a nanoporous polymer thin film (i.e., a nanofiltration membrane). The model linear homopolymer chosen was one that had interactions that were representative of poly(ethylene oxide) (PEO) due to the known interactions of PEO with solution molecules when a PEO chain is dissolved in an aqueous environment. The structural rearrangements of the PEO chain as it passes through the nanopore under an imposed chemical potential gradient was quantified as a function of solvent quality, polymer chain length, nanopore diameter and shape, and PEO-nanopore wall interactions. Thus, these computational studies provide a more detailed picture of the underlying physical mechanisms that drive macromolecular transport through nanopores, and, in particular, how dimensionally-large macromolecules (i.e., with large radii of gyration) enter and move through dimensionally-small pores (i.e., small radii nanopores). The insights gained from these studies will aid in the development of more cost-effective water purification systems in separation technologies for myriad industrial applications.

Direct fabrication of 3D graphene on nanoporous anodic alumina by plasma-enhanced chemical vapor deposition

PubMed Central

Zhan, Hualin; Garrett, David J.; Apollo, Nicholas V.; Ganesan, Kumaravelu; Lau, Desmond; Prawer, Steven; Cervenka, Jiri

2016-01-01

High surface area electrode materials are of interest for a wide range of potential applications such as super-capacitors and electrochemical cells. This paper describes a fabrication method of three-dimensional (3D) graphene conformally coated on nanoporous insulating substrate with uniform nanopore size. 3D graphene films were formed by controlled graphitization of diamond-like amorphous carbon precursor films, deposited by plasma-enhanced chemical vapour deposition (PECVD). Plasma-assisted graphitization was found to produce better quality graphene than a simple thermal graphitization process. The resulting 3D graphene/amorphous carbon/alumina structure has a very high surface area, good electrical conductivity and exhibits excellent chemically stability, providing a good material platform for electrochemical applications. Consequently very large electrochemical capacitance values, as high as 2.1 mF for a sample of 10 mm3, were achieved. The electrochemical capacitance of the material exhibits a dependence on bias voltage, a phenomenon observed by other groups when studying graphene quantum capacitance. The plasma-assisted graphitization, which dominates the graphitization process, is analyzed and discussed in detail. PMID:26805546

Direct fabrication of 3D graphene on nanoporous anodic alumina by plasma-enhanced chemical vapor deposition.

PubMed

Zhan, Hualin; Garrett, David J; Apollo, Nicholas V; Ganesan, Kumaravelu; Lau, Desmond; Prawer, Steven; Cervenka, Jiri

2016-01-25

High surface area electrode materials are of interest for a wide range of potential applications such as super-capacitors and electrochemical cells. This paper describes a fabrication method of three-dimensional (3D) graphene conformally coated on nanoporous insulating substrate with uniform nanopore size. 3D graphene films were formed by controlled graphitization of diamond-like amorphous carbon precursor films, deposited by plasma-enhanced chemical vapour deposition (PECVD). Plasma-assisted graphitization was found to produce better quality graphene than a simple thermal graphitization process. The resulting 3D graphene/amorphous carbon/alumina structure has a very high surface area, good electrical conductivity and exhibits excellent chemically stability, providing a good material platform for electrochemical applications. Consequently very large electrochemical capacitance values, as high as 2.1 mF for a sample of 10 mm(3), were achieved. The electrochemical capacitance of the material exhibits a dependence on bias voltage, a phenomenon observed by other groups when studying graphene quantum capacitance. The plasma-assisted graphitization, which dominates the graphitization process, is analyzed and discussed in detail.

A nanoporous titanium surface promotes the maturation of focal adhesions and formation of filopodia with distinctive nanoscale protrusions by osteogenic cells.

PubMed

Guadarrama Bello, Dainelys; Fouillen, Aurélien; Badia, Antonella; Nanci, Antonio

2017-09-15

While topography is a key determinant of the cellular response to biomaterials, the mechanisms implicated in the cell-surface interactions are complex and still not fully elucidated. In this context, we have examined the effect of nanoscale topography on the formation of filopodia, focal adhesions, and gene expression of proteins associated with cell adhesion and sensing. Commercially pure titanium discs were treated by oxidative nanopatterning with a solution of H 2 SO 4 /H 2 O 2 50:50 (v/v). Scanning electron microscopy and atomic force microscopy characterizations showed that this facile chemical treatment efficiently creates a unique nanoporous surface with a root-mean-square roughness of 11.5nm and pore diameter of 20±5nm. Osteogenic cells were cultured on polished (control) and nanotextured discs for periods of 6, 24, and 72h. Immunofluorescence analysis revealed increases in the adhesion formation per cell area, focal adhesion length, and maturity on the nanoporous surface. Gene expression for various focal adhesion markers, including paxillin and talin, and different integrins (e.g. α1, β1, and α5) was also significantly increased. Scanning electron microscopy revealed the presence of more filopodia on cells grown on the nanoporous surface. These cell extensions displayed abundant and distinctive nanoscale lateral protrusions of 10-15nm diameter that molded the nanopore walls. Together the increase in the focal adhesions and abundance of filopodia and associated protrusions could contribute to strengthening the adhesive interaction of cells with the surface, and thereby, alter the nanoscale biomechanical relationships that trigger cellular cascades that regulate cell behavior. Oxidative patterning was exploited to create a unique three-dimensional network of nanopores on titanium surfaces. Our study illustrates how a facile chemical treatment can be advantageously used to modulate cellular behavior. The nanoscale lateral protrusions on filopodia elicited by this surface are novel adhesive structures. Altogether, the increases in focal adhesion, length, maturity, and filopodia with distinctive lateral protrusions could substantially increase the contact area and adhesion strength of cells, thereby promoting the activation of cellular signaling cascades that may explain the positive osteogenic outcomes previously achieved with this surface. Such physicochemical cueing offers a simple attractive alternative to the use of bioactive agents for guiding tissue repair/regeneration around implantable metals. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Elastic properties of protein functionalized nanoporous polymer films

DOE PAGES

Charles T. Black; Wang, Haoyu; Akcora, Pinar

2015-12-16

Retaining the conformational structure and bioactivity of immobilized proteins is important for biosensor designs and drug delivery systems. Confined environments often lead to changes in conformation and functions of proteins. In this study, lysozyme is chemically tethered into nanopores of polystyrene thin films, and submicron pores in poly(methyl methacrylate) films are functionalized with streptavidin. Nanoindentation experiments show that stiffness of streptavidin increases with decreasing submicron pore sizes. Lysozymes in polystyrene nanopores are found to behave stiffer than the submicron pore sizes and still retain their specific bioactivity relative to the proteins on flat surfaces. Lastly, our results show that proteinmore » functionalized ordered nanoporous polystyrene/poly(methyl methacrylate) films present heterogeneous elasticity and can be used to study interactions between free proteins and designed surfaces.« less

Nanoporous membranes with electrochemically switchable, chemically stabilized ionic selectivity

NASA Astrophysics Data System (ADS)

Small, Leo J.; Wheeler, David R.; Spoerke, Erik D.

2015-10-01

Nanopore size, shape, and surface charge all play important roles in regulating ionic transport through nanoporous membranes. The ability to control these parameters in situ provides a means to create ion transport systems tunable in real time. Here, we present a new strategy to address this challenge, utilizing three unique electrochemically switchable chemistries to manipulate the terminal functional group and control the resulting surface charge throughout ensembles of gold plated nanopores in ion-tracked polycarbonate membranes 3 cm2 in area. We demonstrate the diazonium mediated surface functionalization with (1) nitrophenyl chemistry, (2) quinone chemistry, and (3) previously unreported trimethyl lock chemistry. Unlike other works, these chemistries are chemically stabilized, eliminating the need for a continuously applied gate voltage to maintain a given state and retain ionic selectivity. The effect of surface functionalization and nanopore geometry on selective ion transport through these functionalized membranes is characterized in aqueous solutions of sodium chloride at pH = 5.7. The nitrophenyl surface allows for ionic selectivity to be irreversibly switched in situ from cation-selective to anion-selective upon reduction to an aminophenyl surface. The quinone-terminated surface enables reversible changes between no ionic selectivity and a slight cationic selectivity. Alternatively, the trimethyl lock allows ionic selectivity to be reversibly switched by up to a factor of 8, approaching ideal selectivity, as a carboxylic acid group is electrochemically revealed or hidden. By varying the pore shape from cylindrical to conical, it is demonstrated that a controllable directionality can be imparted to the ionic selectivity. Combining control of nanopore geometry with stable, switchable chemistries facilitates superior control of molecular transport across the membrane, enabling tunable ion transport systems.Nanopore size, shape, and surface charge all play important roles in regulating ionic transport through nanoporous membranes. The ability to control these parameters in situ provides a means to create ion transport systems tunable in real time. Here, we present a new strategy to address this challenge, utilizing three unique electrochemically switchable chemistries to manipulate the terminal functional group and control the resulting surface charge throughout ensembles of gold plated nanopores in ion-tracked polycarbonate membranes 3 cm2 in area. We demonstrate the diazonium mediated surface functionalization with (1) nitrophenyl chemistry, (2) quinone chemistry, and (3) previously unreported trimethyl lock chemistry. Unlike other works, these chemistries are chemically stabilized, eliminating the need for a continuously applied gate voltage to maintain a given state and retain ionic selectivity. The effect of surface functionalization and nanopore geometry on selective ion transport through these functionalized membranes is characterized in aqueous solutions of sodium chloride at pH = 5.7. The nitrophenyl surface allows for ionic selectivity to be irreversibly switched in situ from cation-selective to anion-selective upon reduction to an aminophenyl surface. The quinone-terminated surface enables reversible changes between no ionic selectivity and a slight cationic selectivity. Alternatively, the trimethyl lock allows ionic selectivity to be reversibly switched by up to a factor of 8, approaching ideal selectivity, as a carboxylic acid group is electrochemically revealed or hidden. By varying the pore shape from cylindrical to conical, it is demonstrated that a controllable directionality can be imparted to the ionic selectivity. Combining control of nanopore geometry with stable, switchable chemistries facilitates superior control of molecular transport across the membrane, enabling tunable ion transport systems. Electronic supplementary information (ESI) available: Experimental procedures, synthesis, and characterization of molecules 1, 2 and 3. Explanation of the electrochemical method for approximating nanopore diameter. Additional XPS spectra. See DOI: 10.1039/C5NR02939B

Formation of self-organized nanoporous anodic oxide from metallic gallium.

PubMed

Pandey, Bipin; Thapa, Prem S; Higgins, Daniel A; Ito, Takashi

2012-09-25

This paper reports the formation of self-organized nanoporous gallium oxide by anodization of solid gallium metal. Because of its low melting point (ca. 30 °C), metallic gallium can be shaped into flexible structures, permitting the fabrication of nanoporous anodic oxide monoliths within confined spaces like the inside of a microchannel. Here, solid gallium films prepared on planar substrates were employed to investigate the effects of anodization voltage (1, 5, 10, 15 V) and H(2)SO(4) concentration (1, 2, 4, 6 M) on anodic oxide morphology. Self-organized nanopores aligned perpendicular to the film surface were obtained upon anodization of gallium films in ice-cooled 4 and 6 M aqueous H(2)SO(4) at 10 and 15 V. Nanopore formation could be recognized by an increase in anodic current after a current decrease reflecting barrier oxide formation. The average pore diameter was in the range of 18-40 nm with a narrow diameter distribution (relative standard deviation ca. 10-20%), and was larger at lower H(2)SO(4) concentration and higher applied voltage. The maximum thickness of nanoporous anodic oxide was ca. 2 μm. In addition, anodic formation of self-organized nanopores was demonstrated for a solid gallium monolith incorporated at the end of a glass capillary. Nanoporous anodic oxide monoliths formed from a fusible metal will lead to future development of unique devices for chemical sensing and catalysis.

Synthesis of copper oxide nanowires and nanoporous copper via environmentally friendly transformation of bulk copper-calcium alloys.

PubMed

Zhang, X; Turcheniuk, K; Zusmann, B; Benson, J; Nelson, S; Luo, S; Magasinski, A; Yushin, G

2018-05-24

In this work, we report a novel, one-step, inexpensive and environmentally friendly synthesis of Cu nanostructures by means of chemical de-alloying of bulk Cu-Ca alloys in aqueous solutions. By controlling the synthesis conditions, we tune the morphology of the nanostructured Cu from nanoporous Cu to copper oxide nanowires.

An Optoelectronic Nose for Detection of Toxic Gases

PubMed Central

Lim, Sung H.; Feng, Liang; Kemling, Jonathan W.; Musto, Christopher J.; Suslick, Kenneth S.

2009-01-01

We have developed a simple colorimetric sensor array (CSA) for the detection of a wide range of volatile analytes and applied it to the detection of toxic gases. The sensor consists of a disposable array of cross-responsive nanoporous pigments whose colors are changed by diverse chemical interactions with analytes. Although no single chemically responsive pigment is specific for any one analyte, the pattern of color change for the array is a unique molecular fingerprint. Clear differentiation among 19 different toxic industrial chemicals (TICs) within two minutes of exposure at IDLH (immediately dangerous to life or health) concentration has been demonstrated. Quantification of each analyte is easily accomplished based on the color change of the array, and excellent detection limits have been demonstrated, generally below the PELs (permissible exposure limits). Identification of the TICs was readily achieved using a standard chemometric approach, i.e., hierarchical clustering analysis (HCA), with no misclassifications over 140 trials. PMID:20160982

Colorimetric sensor array for determination and identification of toxic industrial chemicals.

PubMed

Feng, Liang; Musto, Christopher J; Kemling, Jonathan W; Lim, Sung H; Zhong, Wenxuan; Suslick, Kenneth S

2010-11-15

A low-cost yet highly sensitive colorimetric sensor array for the detection and identification of toxic industrial chemicals (TICs) has been developed. The sensor consists of a disposable array of cross-responsive nanoporous pigments whose colors are changed by diverse chemical interactions with analytes. Clear differentiation among 20 different TICs has been easily achieved at both their IDLH (immediately dangerous to life or health) concentration within 2 min of exposure and PEL (permissible exposure limit) concentration within 5 min of exposure with no errors or misclassifications. Detection limits are generally well below the PEL (in most cases below 5% of PEL) and are typically in the low ppb range. The colorimetric sensor array is not responsive to changes in humidity or temperature over a substantial range. The printed arrays show excellent batch to batch reproducibility and long shelf life (greater than 3 months).

An optoelectronic nose for the detection of toxic gases.

PubMed

Lim, Sung H; Feng, Liang; Kemling, Jonathan W; Musto, Christopher J; Suslick, Kenneth S

2009-10-01

We have developed a simple colorimetric sensor array that detects a wide range of volatile analytes and then applied it to the detection of toxic gases. The sensor consists of a disposable array of cross-responsive nanoporous pigments with colours that are changed by diverse chemical interactions with analytes. Although no single chemically responsive pigment is specific for any one analyte, the pattern of colour change for the array is a unique molecular fingerprint. Clear differentiation among 19 different toxic industrial chemicals (TICs) within two minutes of exposure at concentrations immediately dangerous to life or health were demonstrated. Based on the colour change of the array, quantification of each analyte was accomplished easily, and excellent detection limits were achieved, generally below the permissible exposure limits. Different TICs were identified readily using a standard chemometric approach (hierarchical clustering analysis), with no misclassifications over 140 trials.

Nanoporous thermosetting polymers.

PubMed

Raman, Vijay I; Palmese, Giuseppe R

2005-02-15

Potential applications of nanoporous thermosetting polymers include polyelectrolytes in fuel cells, separation membranes, adsorption media, and sensors. Design of nanoporous polymers for such applications entails controlling permeability by tailoring pore size, structure, and interface chemistry. Nanoporous thermosetting polymers are often synthesized via free radical mechanisms using solvents that phase separate during polymerization. In this work, a novel technique for the synthesis of nanoporous thermosets is presented that is based on the reactive encapsulation of an inert solvent using step-growth cross-linking polymerization without micro/macroscopic phase separation. The criteria for selecting such a monomer-polymer-solvent system are discussed based on FTIR analysis, observed micro/macroscopic phase separation, and thermodynamics of swelling. Investigation of resulting network pore structures by scanning electron microscopy (SEM) and small-angle X-ray scattering following extraction and supercritical drying using carbon dioxide showed that nanoporous polymeric materials with pore sizes ranging from 1 to 50 nm can be synthesized by varying the solvent content. The differences in the porous morphology of these materials compared to more common free radically polymerized analogues that exhibit phase separation were evident from SEM imaging. Furthermore, it was demonstrated that the chemical activity of the nanoporous materials obtained by our method could be tailored by grafting appropriate functional groups at the pore interface.

Nanoporous hard data: optical encoding of information within nanoporous anodic alumina photonic crystals.

PubMed

Santos, Abel; Law, Cheryl Suwen; Pereira, Taj; Losic, Dusan

2016-04-21

Herein, we present a method for storing binary data within the spectral signature of nanoporous anodic alumina photonic crystals. A rationally designed multi-sinusoidal anodisation approach makes it possible to engineer the photonic stop band of nanoporous anodic alumina with precision. As a result, the transmission spectrum of these photonic nanostructures can be engineered to feature well-resolved and selectively positioned characteristic peaks across the UV-visible spectrum. Using this property, we implement an 8-bit binary code and assess the versatility and capability of this system by a series of experiments aiming to encode different information within the nanoporous anodic alumina photonic crystals. The obtained results reveal that the proposed nanosized platform is robust, chemically stable, versatile and has a set of unique properties for data storage, opening new opportunities for developing advanced nanophotonic tools for a wide range of applications, including sensing, photonic tagging, self-reporting drug releasing systems and secure encoding of information.

Gold/silver coated nanoporous ceramic membranes: a new substrate for SERS studies

NASA Astrophysics Data System (ADS)

Kassu, A.; Robinson, P.; Sharma, A.; Ruffin, P. B.; Brantley, C.; Edwards, E.

2010-08-01

Surface Enhanced Raman Scattering (SERS) is a recently discovered powerful technique which has demonstrated sensitivity and selectivity for detecting single molecules of certain chemical species. This is due to an enhancement of Raman scattered light by factors as large as 1015. Gold and Silver-coated substrates fabricated by electron-beam lithography on Silicon are widely used in SERS technique. In this paper, we report the use of nanoporous ceramic membranes for SERS studies. Nanoporous membranes are widely used as a separation membrane in medical devices, fuel cells and other studies. Three different pore diameter sizes of commercially available nanoporous ceramic membranes: 35 nm, 55nm and 80nm are used in the study. To make the membranes SERS active, they are coated with gold/silver using sputtering techniques. We have seen that the membranes coated with gold layer remain unaffected even when immersed in water for several days. The results show that gold coated nanoporous membranes have sensitivity comparable to substrates fabricated by electron-beam lithography on Silicon substrates.

Nanoporous hard data: optical encoding of information within nanoporous anodic alumina photonic crystals

NASA Astrophysics Data System (ADS)

Santos, Abel; Law, Cheryl Suwen; Pereira, Taj; Losic, Dusan

2016-04-01

Herein, we present a method for storing binary data within the spectral signature of nanoporous anodic alumina photonic crystals. A rationally designed multi-sinusoidal anodisation approach makes it possible to engineer the photonic stop band of nanoporous anodic alumina with precision. As a result, the transmission spectrum of these photonic nanostructures can be engineered to feature well-resolved and selectively positioned characteristic peaks across the UV-visible spectrum. Using this property, we implement an 8-bit binary code and assess the versatility and capability of this system by a series of experiments aiming to encode different information within the nanoporous anodic alumina photonic crystals. The obtained results reveal that the proposed nanosized platform is robust, chemically stable, versatile and has a set of unique properties for data storage, opening new opportunities for developing advanced nanophotonic tools for a wide range of applications, including sensing, photonic tagging, self-reporting drug releasing systems and secure encoding of information.Herein, we present a method for storing binary data within the spectral signature of nanoporous anodic alumina photonic crystals. A rationally designed multi-sinusoidal anodisation approach makes it possible to engineer the photonic stop band of nanoporous anodic alumina with precision. As a result, the transmission spectrum of these photonic nanostructures can be engineered to feature well-resolved and selectively positioned characteristic peaks across the UV-visible spectrum. Using this property, we implement an 8-bit binary code and assess the versatility and capability of this system by a series of experiments aiming to encode different information within the nanoporous anodic alumina photonic crystals. The obtained results reveal that the proposed nanosized platform is robust, chemically stable, versatile and has a set of unique properties for data storage, opening new opportunities for developing advanced nanophotonic tools for a wide range of applications, including sensing, photonic tagging, self-reporting drug releasing systems and secure encoding of information. Electronic supplementary information (ESI) available: Further details about anodisation profiles, SEM cross-section images, digital pictures, transmission spectra, photonic barcodes and ASCII codes of the different NAA photonic crystals fabricated and analysed in our study. See DOI: 10.1039/c6nr01068g

Controlling Ionic Transport for Device Design in Synthetic Nanopores

NASA Astrophysics Data System (ADS)

Kalman, Eric Boyd

Polymer nanopores present a number of behaviors not seen in microscale systems, such as ion current rectification, ionic selectivity, size exclusion and potential dependent ion concentrations in and near the pore. The existence of these effects stems from the small size of nanopores with respect to the characteristic length scales of surface interactions at the interface between the nanopore surface and the solution within it. The large surface-to-volume ratio due to the nanoscale geometry of a nanopore, as well as similarity in scale between geometry and interaction demands the solution interact with the nanopore walls. As surfaces in solution almost always carry residual charge, these surface forces are primarily the electrostatic interactions between the charge groups on the pore surface and the ions in solution. These interactions may be used by the experimentalist to control ionic transport through synthetic nanopores, and use them as a template for the construction of devices. In this research, we present our work on creating a number of ionic analogs to seminal electronic devices, specifically diodes, and transistors, by controlling ionic transport through the electrostatic interactions between a single synthetic nanopore and ions. Control is achieved by "doping" the effective charge carrier concentration in specific regions of the nanopore through manipulation of the pore's surface charge. This manipulation occurs through two mechanisms: chemical modification of the surface charge and electrostatic manipulation of the local internal nanopore potential using a gate electrode. Additionally, the innate selectivity of the charged nanopores walls allows for the separation of charges in solution. This well-known effect, which spawns measureable quantities, the streaming potential and current, has been used to create nanoscale water desalination membranes. We attempt to create a device using membranes with large nanopore densities for the desalination of water which should theoretically outperform currently available devices, as through our previous work we have developed techniques allowing for transport manipulation not current accessible in traditional membrane motifs.

Metal-Organic Framework Thin Film Coated Optical Fiber Sensors: A Novel Waveguide-Based Chemical Sensing Platform.

PubMed

Kim, Ki-Joong; Lu, Ping; Culp, Jeffrey T; Ohodnicki, Paul R

2018-02-23

Integration of optical fiber with sensitive thin films offers great potential for the realization of novel chemical sensing platforms. In this study, we present a simple design strategy and high performance of nanoporous metal-organic framework (MOF) based optical gas sensors, which enables detection of a wide range of concentrations of small molecules based upon extremely small differences in refractive indices as a function of analyte adsorption within the MOF framework. Thin and compact MOF films can be uniformly formed and tightly bound on the surface of etched optical fiber through a simple solution method which is critical for manufacturability of MOF-based sensor devices. The resulting sensors show high sensitivity/selectivity to CO 2 gas relative to other small gases (H 2 , N 2 , O 2 , and CO) with rapid (

Design and fabrication of nanoelectrodes for applications with scanning electrochemical microscopy

NASA Astrophysics Data System (ADS)

Thakar, Rahul

Scanning electrochemical microscope (SECM) was introduced two decades ago and has since emerged as a powerful research tool to investigate localized electrochemical reactions at the surface of material and biological samples. The ability to obtain chemical information at a surface differentiates SECM from competing scanning probe microscopy (SPM) techniques. Although, chemical specificity is a unique advantage offered by SECM, inherent limitations due to a slow feedback response, and challenges associated with production of smaller electrodes have remained major drawbacks. Initially in this research, SECM was utilized as a characterization and investigative tool. Later, advances in SECM imaging were achieved with design and production of multifunctional nanoelectrodes. At first, platinum based nanoelectrodes were fabricated for use as electrochemical probes to investigate local electron transfer at chemically-modified surfaces. Further, micron and sub-micron platinum electrodes with chemically modified shrouds were prepared and characterized with voltammetric measurements. Studies reveal experimental evidence for the presence of edge-effects that are typically associated with submicron electrodes. Interestingly, we observed selectivity of these electrodes based on hydrophobic/ hydrophilic character. Through vapor deposition of parylene over microstructured material, single-pore membranes and porous membrane arrays were produced. Pore size characterization within porous membranes was performed with templated growth of micro/nanostructures. Characterization of transport properties of ions and redox-active molecules through hydrophobic parylene membranes was investigated with ion conductance microscopy and SECM, individually. Parylene is an insulative material that is chemically resistant, deposits conformally over high-aspect ratio objects and also converts into conductive carbon at high-temperature pyrolysis. Motivated by these results we identified a unique strategy to fabricate parylene based carbon electrodes Here, we have developed a unique strategy to obtain carbon based nanoelectrodes from vapor deposition of parylene over pulled glass nanopipettes. With this approach, multiple electrode geometries were constructed and the application of individual geomtery with SECM is demonstrated. In particular, enhanced spatial resolution and electrochemical information were obtained with the use of carbon ring/nanopore electrodes. Practical implications of edge-effects observed with carbon ring/nanopore electrodes is discussed with substrate generation tip collection (SG/TC) SECM Carbon ring/nanopore electrodes have also enabled the use of SECM in conjunction with ion conductance microscopy to alleviate the issue of poor feedback response. This has further helped in deconvolution of electrochemcial and topographical signals. Although, use of carbon nanoelectrodes is discussed with specific applications to electrochemcial microscopy, these probes have wide utility in electroanalytical applications. Initial proof-of-concept experiments along with future directions for this work are presented.

Nonlinear primary resonance of micro/nano-beams made of nanoporous biomaterials incorporating nonlocality and strain gradient size dependency

NASA Astrophysics Data System (ADS)

Sahmani, S.; Aghdam, M. M.

2018-03-01

A wide range of biological applications such as drug delivery, biosensors and hemodialysis can be provided by nanoporous biomaterials due to their uniform pore size as well as considerable pore density. In the current study, the size dependency in the nonlinear primary resonance of micro/nano-beams made of nanoporous biomaterials is anticipated. To accomplish this end, a refined truncated cube is introduced to model the lattice structure of nanoporous biomaterial. Accordingly, analytical expressions for the mechanical properties of material are derived as functions of pore size. After that, based upon a nonlocal strain gradient beam model, the size-dependent nonlinear Duffing type equation of motion is constructed. The Galerkin technique together with the multiple time-scales method is employed to obtain the nonlocal strain gradient frequency-response and amplitude-response related to the nonlinear primary resonance of a micro/nano-beam made of the nanoporous biomaterial with different pore sizes. It is indicated that the nonlocality causes to decrease the response amplitudes associated with the both bifurcation points of the jump phenomenon, while the strain gradient size dependency causes to increase them. Also, it is found that increasing the pore size leads to enhance the nonlinearity, so the maximum deflection of response occurs at higher excitation frequency.

Synthesis of nanoporous TiO2 materials using a doubly surfactant system and applying them as useful adsorbents

NASA Astrophysics Data System (ADS)

Anbia, Mansoor; Khosravi, Faezeh

Hydrothermal and non-hydrothermal nanoporous TiO2 materials were synthesized via a doubly surfactant route by using cationic cetyltrimethylammonium bromide and anionic sodium dodecyl sulfate surfactants as the molecular template/structure directing agent. Hydrothermal treatment was performed for comparison. The bulk chemical and phase compositions, crystalline structures, particle morphologies, thermal stabilities and surface texturing were determined by means of X-ray powder analysis, SEM and N2 sorptiometry. The nanoporous TiO2 materials were found to have a spherical morphology with a diameter range of 50-200 nm and a high surface area (390 m2 g-1). Hydrothermal and non-hydrothermal nanoporous TiO2 materials were applied for adsorption of heavy metal cations and the toxic organic compound, copper phthalocyanine, from water for evaluation of their adsorption properties. Both nanoporous TiO2 materials were found to have similar adsorption capacities toward heavy metal cations and CuPc. Both hydrothermal and non-hydrothermal TiO2 nanoporous materials were found to have very good potential for application as a new adsorbent especially for adsorbing heavy metal cations from wastewaters.

Photochemistry of nanoporous carbons: Perspectives in energy conversion and environmental remediation.

PubMed

Gomis-Berenguer, Alicia; Velasco, Leticia F; Velo-Gala, Inmaculada; Ania, Conchi O

2017-03-15

The interest in the use of nanoporous carbon materials in applications related to energy conversion and storage, either as catalysts or additives, has grown over recent decades in various disciplines. Since the early studies reporting the benefits of the use of nanoporous carbons as inert supports of semiconductors and as electron acceptors that enhance the splitting of the photogenerated excitons, many researchers have investigated the key role of carbon matrices coupled to all types of photoactive materials. More recently, our group has demonstrated the ability of semiconductor-free nanoporous carbons to convert the absorbed photons into chemical reactions (i.e. oxidation of pollutants, water splitting, reduction of surface groups) opening new opportunities beyond conventional applications in light energy conversion. The aim of this paper is to review the recent progress on the application of nanoporous carbons in photochemistry using varied illumination conditions (UV, simulated solar light) and covering their role as additives to semiconductors as well as their use as photocatalysts in various fields, describing the photochemical quantum yield of nanoporous carbons for different reactions, and discussing the mechanisms postulated for the carbon/light interactions in confined pore spaces. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Silicon deposition in nanopores using a liquid precursor.

PubMed

Masuda, Takashi; Tatsuda, Narihito; Yano, Kazuhisa; Shimoda, Tatsuya

2016-11-22

Techniques for depositing silicon into nanosized spaces are vital for the further scaling down of next-generation devices in the semiconductor industry. In this study, we filled silicon into 3.5-nm-diameter nanopores with an aspect ratio of 70 by exploiting thermodynamic behaviour based on the van der Waals energy of vaporized cyclopentasilane (CPS). We originally synthesized CPS as a liquid precursor for semiconducting silicon. Here we used CPS as a gas source in thermal chemical vapour deposition under atmospheric pressure because vaporized CPS can fill nanopores spontaneously. Our estimation of the free energy of CPS based on Lifshitz van der Waals theory clarified the filling mechanism, where CPS vapour in the nanopores readily undergoes capillary condensation because of its large molar volume compared to those of other vapours such as water, toluene, silane, and disilane. Consequently, a liquid-specific feature was observed during the deposition process; specifically, condensed CPS penetrated into the nanopores spontaneously via capillary force. The CPS that filled the nanopores was then transformed into solid silicon by thermal decomposition at 400 °C. The developed method is expected to be used as a nanoscale silicon filling technology, which is critical for the fabrication of future quantum scale silicon devices.

Silicon deposition in nanopores using a liquid precursor

NASA Astrophysics Data System (ADS)

Masuda, Takashi; Tatsuda, Narihito; Yano, Kazuhisa; Shimoda, Tatsuya

2016-11-01

Techniques for depositing silicon into nanosized spaces are vital for the further scaling down of next-generation devices in the semiconductor industry. In this study, we filled silicon into 3.5-nm-diameter nanopores with an aspect ratio of 70 by exploiting thermodynamic behaviour based on the van der Waals energy of vaporized cyclopentasilane (CPS). We originally synthesized CPS as a liquid precursor for semiconducting silicon. Here we used CPS as a gas source in thermal chemical vapour deposition under atmospheric pressure because vaporized CPS can fill nanopores spontaneously. Our estimation of the free energy of CPS based on Lifshitz van der Waals theory clarified the filling mechanism, where CPS vapour in the nanopores readily undergoes capillary condensation because of its large molar volume compared to those of other vapours such as water, toluene, silane, and disilane. Consequently, a liquid-specific feature was observed during the deposition process; specifically, condensed CPS penetrated into the nanopores spontaneously via capillary force. The CPS that filled the nanopores was then transformed into solid silicon by thermal decomposition at 400 °C. The developed method is expected to be used as a nanoscale silicon filling technology, which is critical for the fabrication of future quantum scale silicon devices.

Colorimetric Detection and Identification of Natural and Artificial Sweeteners

PubMed Central

Musto, Christopher J.; Lim, Sung H.; Suslick, Kenneth S.

2009-01-01

A disposable, low-cost colorimetric sensor array has been created by pin-printing onto a hydrophilic membrane 16 chemically responsive nanoporous pigments made from indicators immobilized in an organically modified silane (ormosil). The array has been used to detect and identify 14 different natural and artificial sweeteners at millimolar concentrations as well as commonly used individual serving sweetener packets. The array has shown excellent reproducibility and long shelf-life and has been optimized to work in the biological pH regime. PMID:20337402

Colorimetric detection and identification of natural and artificial sweeteners.

PubMed

Musto, Christopher J; Lim, Sung H; Suslick, Kenneth S

2009-08-01

A disposable, low-cost colorimetric sensor array has been created by pin-printing onto a hydrophilic membrane 16 chemically responsive nanoporous pigments that are comprised of indicators immobilized in an organically modified silane (ormosil). The array has been used to detect and identify 14 different natural and artificial sweeteners at millimolar concentrations, as well as commonly used individual-serving sweetener packets. The array has shown excellent reproducibility and long shelf life and has been optimized to work in the biological pH regime.

Modulation of Molecular Flux Using a Graphene Nanopore Capacitor.

PubMed

Shankla, Manish; Aksimentiev, Aleksei

2017-04-20

Modulation of ionic current flowing through nanoscale pores is one of the fundamental biological processes. Inspired by nature, nanopores in synthetic solid-state membranes are being developed to enable rapid analysis of biological macromolecules and to serve as elements of nanofludic circuits. Here, we theoretically investigate ion and water transport through a graphene-insulator-graphene membrane containing a single, electrolyte-filled nanopore. By means of all-atom molecular dynamics simulations, we show that the charge state of such a graphene nanopore capacitor can regulate both the selectivity and the magnitude of the nanopore ionic current. At a fixed transmembrane bias, the ionic current can be switched from being carried by an equal mixture of cations and anions to being carried almost exclusively by either cationic or anionic species, depending on the sign of the charge assigned to both plates of the capacitor. Assigning the plates of the capacitor opposite sign charges can either increase the nanopore current or reduce it substantially, depending on the polarity of the bias driving the transmembrane current. Facilitated by the changes of the nanopore surface charge, such ionic current modulations are found to occur despite the physical dimensions of the nanopore being an order of magnitude larger than the screening length of the electrolyte. The ionic current rectification is accompanied by a pronounced electro-osmotic effect that can transport neutral molecules such as proteins and drugs across the solid-state membrane and thereby serve as an interface between electronic and chemical signals.

Influence of nanoporosity on biological response of sol-gel-derived 70S30C bioactive glass monoliths

NASA Astrophysics Data System (ADS)

Thamma, Ukrit

In the field of bioactive glasses for hard tissue regeneration, the bioactivity of a material is measured by its ability to induce the formation of hydroxyapatite (HA), Ca10(PO4)6(OH)2, under physiological conditions. Due to its close chemical crystallographic resemblance to natural bones, the newly formed HA layer has been shown to be critical for the biological interaction and bonding between the surfaces of bioactive glasses and osteoblast (bone) cells. Since the formation mechanism of HA is dependent on the dissolution behavior of the bioactive glass substrate, the characteristics of HA layer are dominated by the glass composition and structure. By introducing nanoporosity into glass structure, the dissolution rate and HA growth rate on nanoporous sol-gel-derived glasses are drastically enhanced compared to that of non-porous melt-quench glasses with the same composition. While enhanced HA growth on nanoporous glass, compared to non-porous glass, was hypothesized to be associated with greater specific surface area (SSA), other studies argued that growth rate of HA layer on nanoporous glass is dominated by nanopore size distribution, and minimally affected by the bulk SSA of the underlying glass. In order to decouple the influence of nanopore size and SSA on HA formation, we have successfully fabricated homogeneous 70S30C bioactive glass monoliths with different nanopore sizes, yet similar SSA via sol-gel process. After 3-day PBS incubation of 70S30C nanoporous glass monoliths, the presence of hydroxyapatite and Type-B carbonated hydroxyapatite (HA/B-CHA) was confirmed by XPS and FTIR. Here, we report the influence of nanopore size on HA/CHA formation pathway, growth rate, and its microstructure. Due to pore-size limited diffusion of PO43-, two HA/CHA formation pathways were observed: HA/CHA surface deposition and/or HA/CHA incorporation into nanopores. HA/CHA growth rate on the surface of a nanoporous glass monolith is dominated by the pore-size limited transport of Ca2+ ions dissolved from nanoporous glass substrates. Furthermore, with rising overall growth rate controlled by nanopore size, HA/CHA microstructures evolved from needle-like, plate-like, and flower-like, respectively. Furthermore, the levels of initial cell attachment and protein adsorption on HA/CHA microstructures formed on different nanopore sizes were investigated. The initial cell attachment was quantified by measuring the density and average size of attached MC3T3-E1 cells after 2-hour seeding period. The amounts and conformation of adsorbed proteins after 2-hour incubation with HA/CHA were characterized by Western blot and FTIR, respectively. It was shown that the amounts of protein adsorption on various HA/CHA microstructures do not correlate with the initial MC3T3-E1 attachment, while the beta-sheet/alpha-helix ratios in Amide I of bovine albumin serum (BSA) adsorbed on HA/CHA microstructures do correlate to the level of initial cell attachment. This result suggests that the beta-sheet structure in BSA interacts with and activates the RGD sequence of adhesion proteins, such as fibronectin, upon adsorption, thus significantly enhancing the initial attachment of MC3T3-E1 cells. These findings provide new insights that can lead to a more detailed fundamental understanding of protein-surface and protein-protein interactions, which are crucial for the further development of bioactive material.

Ionic Transport through Chemically Functionalized Hydrogen Peroxide-Sensitive Asymmetric Nanopores.

PubMed

Ali, Mubarak; Ahmed, Ishtiaq; Nasir, Saima; Ramirez, Patricio; Niemeyer, Christof M; Mafe, Salvador; Ensinger, Wolfgang

2015-09-09

We describe the fabrication of a chemical-sensitive nanofluidic device based on asymmetric nanopores whose transport characteristics can be modulated upon exposure to hydrogen peroxide (H2O2). We show experimentally and theoretically that the current-voltage curves provide a suitable method to monitor the H2O2-mediated change in pore surface characteristics from the electronic readouts. We demonstrate also that the single pore characteristics can be scaled to the case of a multipore membrane whose electric outputs can be readily controlled. Because H2O2 is an agent significant for medical diagnostics, the results should be useful for sensing nanofluidic devices.

Influence of Chemical Conditions on the Nanoporous Structure of Silicate Aerogels

PubMed Central

Sinkó, Katalin

2010-01-01

Silica or various silicate aerogels can be characterized by highly porous, open cell, low density structures. The synthesis parameters influence the three-dimensional porous structures by modifying the kinetics and mechanism of hydrolysis and condensation processes. Numerous investigations have shown that the structure of porous materials can be tailored by variations in synthesis conditions (e.g., the type of precursors, catalyst, and surfactants; the ratio of water/precursor; the concentrations; the medium pH; and the solvent). The objectives of this review are to summarize and elucidate the effects of chemical conditions on the nanoporous structure of sol-gel derived silicate aerogels.

Facile fabrication of nanofluidic diode membranes using anodic aluminium oxide.

PubMed

Wu, Songmei; Wildhaber, Fabien; Vazquez-Mena, Oscar; Bertsch, Arnaud; Brugger, Juergen; Renaud, Philippe

2012-09-21

Active control of ion transport plays important roles in chemical and biological analytical processes. Nanofluidic systems hold the promise for such control through electrostatic interaction between ions and channel surfaces. Most existing experiments rely on planar geometry where the nanochannels are generally very long and shallow with large aspect ratios. Based on this configuration the concepts of nanofluidic gating and rectification have been successfully demonstrated. However, device minimization and throughput scaling remain significant challenges. We report here an innovative and facile realization of hetero-structured Al(2)O(3)/SiO(2) (Si) nanopore array membranes by using pattern transfer of self-organized nanopore structures of anodic aluminum oxide (AAO). Thanks to the opposite surface charge states of Al(2)O(3) (positive) and SiO(2) (negative), the membrane exhibits clear rectification of ion current in electrolyte solutions with very low aspect ratios compared to previous approaches. Our hetero-structured nanopore arrays provide a valuable platform for high throughput applications such as molecular separation, chemical processors and energy conversion.

Comparative study of the anchorage and the catalytic properties of nanoporous TiO2 films modified with ruthenium (II) and rhenium (I) carbonyl complexes

NASA Astrophysics Data System (ADS)

Oyarzún, Diego P.; Chardon-Noblat, Sylvie; Linarez Pérez, Omar E.; López Teijelo, Manuel; Zúñiga, César; Zarate, Ximena; Shott, Eduardo; Carreño, Alexander; Arratia-Perez, Ramiro

2018-02-01

In this article we study the anchoring of cis-[Ru(bpyC4pyr)(CO)2(CH3CN)2]2+, cis-[Ru(bpy)2(CO)2]2+ and cis-[Ru(bpyac)(CO)2Cl2], onto nanoporous TiO2 employing electropolymerization, electrostatic interaction and chemical bonding. Also, the [Re(bpyac)(CO)3Cl] rhenium(I) complex for chemical anchorage was analyzed. The characterization of TiO2/Ru(II) and TiO2/Re(I) nanocomposite films was performed by field emission scanning electron microscopy (FESEM), electron dispersive X-ray spectroscopy (EDS) and Raman spectroscopy. In addition, for the more stable nanocomposites obtained, the catalytic properties (solar energy conversion and CO2 reduction) were evaluated. The efficiency improvement in redox process derived from the (photo)electrochemical evidence indicates that modified nanoporous TiO2 structures enhance the rate of charge transfer reactions.

Mapping DNA Methylation with High Throughput Nanopore Sequencing

PubMed Central

Rand, Arthur C.; Jain, Miten; Eizenga, Jordan M.; Musselman-Brown, Audrey; Olsen, Hugh E.; Akeson, Mark

2017-01-01

Chemical modifications to DNA regulate its biological function. We present a framework for mapping methylation to cytosine and adenosine with the Oxford Nanopore Technologies MinION using its ionic current signal. We map three cytosine variants and two adenine variants. The results show that our model is sensitive enough to detect changes in genomic DNA methylation levels as a function of growth phase in E. coli. PMID:28218897

EDITORIAL: Nanopores—the 'Holey Grail' in nanotechnology research Nanopores—the 'Holey Grail' in nanotechnology research

NASA Astrophysics Data System (ADS)

Demming, Anna

2012-06-01

'Negative space' may be as important in the development of nanomaterials as it is in creating works of art. The term refers to the space around and between objects, an important aspect in artistic composition. In nanotechnology, while nanoposts and nanowires have been assiduously studied and exploited for enhancing the performance of solar cells [1], real-time chemical sensors [2], UV emitters [3] and many other applications, nanopore structures have also yielded important advances in a wide range of fields. In this issue Melnikov, Leburton and Gracheva report on the electrostatic properties of nanopores in a layered semiconductor, and show how they allow a more accurate characterization of DNA than pores in other membranes [4]. Nanoporous materials have been applied to a diverse range of technological challenges. In recognition of its potential in high-efficiency solar cells, Prakasam and colleagues in the US reported the first ever synthesis of self-aligned nanoporous haematite [5]. Haematite is abundant, stable, non-toxic and has a band gap in the visible region and, as their work demonstrates, the photoresponse of nanoporous haematite is very promising for energy harvesting applications. Nanoporous aluminum oxide has also proved to be a particularly valuable material in applications ranging from liquid display panels to biosensor microchips. A collaboration of researchers in Taiwan demonstrated that porous aluminum oxide on an indium tin oxide surface could act as an alignment layer in liquid crystal display panels that have a transmittance of 60-80%, and switch from black to bright with a response time of 62.5 ms [6]. In Korea, Chung, Son and Min investigated the effect of nanostructural parameters of porous aluminum oxide on cell adhesion and proliferation for cell-based microchips [7]. While aluminum oxide without any modifications is not favourable for adherent cell culture, the proliferation of cells dramatically increased in porous aluminum oxide, particularly when the aspect ratio of the nanopore was near unity. In the mid 1990s a collaboration of researchers in the US demonstrated that nanopores could be used to characterize DNA [8]. They showed that as an electric field drove DNA molecules through a pore in a lipid bilayer membrane, the decrease in ionic current due to the partially blocked channel allowed measurement of the polynucleotide length. 'With further improvements, the method could in principle provide direct, high-speed detection of the sequence of bases in single molecules of DNA or RNA', suggested the authors. The idea inspired a catalogue of further research. Gracheva and colleagues in Illinois described a modified approach to detecting DNA using a nanopore in a membrane fabricated from a metal-oxide-semiconductor (MOS) capacitor [9]. The use of semiconductor materials allows the direct integration of high-sensitivity nanoscale MOS amplifiers on the nanopore layer structure to improve the signal. Researchers in the Netherlands have investigated ways of refining geometrical control of nanopores in SiN membranes for more accurate molecular characterization [10]. They reported the fabrication of nanopores using transmission electron microscope beams of different sizes. They found that the stability of small nanopores is related to their geometry, which could be controlled by the size of the beam used in fabrication. One challenge for accurate DNA characterization has been the speed of translocation through the pore. In a collaboration between the University of Illinois and the University of Notre-Dame in Indiana, researchers used a time-varying electric field to slow down the molecule's passage in the pore [11]. In this issue, researchers in Illinois have studied the translocation and stretching of DNA in a pore in a semiconductor membrane consisting of doped p- and n-layers of Si forming a p-n-junction [4]. Control over the stretching of the DNA is important, as is controlling the speed of translocation. Interference between the secondary structure of the probed molecule can interfere with the recorded signal, muddling measurements of the molecule's charge. According to Gracheva and her colleagues, 'the results indicate that the tunable local electric field inside the membrane can effectively control dynamics of a DNA in the channel to either momentarily trap, slow down or allow the biomolecule to translocate at will'. The fertility of research based on nanopores complements well the interest in nanowires and nanoposts. This may largely be a symptom of the comprehensive rigour in scientific enquiry which encourages the investigation of all approaches to a solution. It was once suggested that 'art and science have their meeting point in method' [12]. One might also argue that the creative and inspired ingenuity that is evident in the application of nanopores to such wide-ranging technological challenges demonstrates how the development of scientific methods is in itself a fine art. References [1] Qiu J et al 2010 Solution-derived 40 μm vertically aligned ZnO nanowire arrays as photoelectrodes in dye-sensitized solar cells Nanotechnology 21 195602 [2] Park I, Li Z, Pisano A P and Williams R S 2010 Top-down fabricated silicon nanowire sensors for real-time chemical detection Nanotechnology 21 015501 [3] Gao J et al 2011 UV light emitting transparent conducting tin-doped indium oxide (ITO) nanowires Nanotechnology 22 195706 [4] Melnikov D V, Leburton J-P and Gracheva M E 2012 Slowing down and stretching DNA with an electrically tunable nanopore in a p-n semiconductor membrane Nanotechnology 23 255501 [5] Prakasam H E, Varghese O K, Paulose M, Mor G K and Grimes C A 2006 Synthesis and photoelectrochemical properties of nanoporous iron (III) oxide by potentiostatic anodization Nanotechnology 17 4285-91 [6] Hong C, Tang T-T, Hung C-Y, Pan R-P and Fang W 2010 Liquid crystal alignment in nanoporous anodic aluminum oxide layer for LCD panel applications Nanotechnology 21 285201 [7] Chung S H, Son S J and Min J 2010 The nanostructure effect on the adhesion and growth rates of epithelial cells with well-defined nanoporous alumina s substrates Nanotechnology 21 125104 [8] Kasianowicz J J, Brandin E, Branton D and Deamer D W 1996 Characterization of individual polynucleotide molecules using a membrane channel Proc. Natl Acad. Sci. 93 13770-3 [9] Gracheva M E, Xiong A, Aksimentiev A, Schulten K, Timp G and Leburton J-P 2006 Simulation of the electric response of DNA translocation through a semiconductor nanopore-capacitor Nanotechnology 17 622-33 [10] Van Den Hout M, Hall A R, Wu M Y, Zandbergen H W, Dekker C and Dekker N H 2010 Controlling nanopore size, shape and stability Nanotechnology 21 115304 [11] Mirsaidov U, Comer J, Dimitrov V, Aksimentiev A and Timp G 2010 Slowing the translocation of double-stranded DNA using a nanopore smaller than the double helix Nanotechnology 21 395501 [12] Baron E and Bulwer L L 1864 Caxtoniana vol 2 (Leipzig: Bernard Tauchnits) p 122

Mechanism of How Salt-Gradient-Induced Charges Affect the Translocation of DNA Molecules through a Nanopore

PubMed Central

He, Yuhui; Tsutsui, Makusu; Scheicher, Ralph H.; Fan, Chun; Taniguchi, Masateru; Kawai, Tomoji

2013-01-01

Experiments using nanopores demonstrated that a salt gradient enhances the capture rate of DNA and reduces its translocation speed. These two effects can help to enable electrical DNA sequencing with nanopores. Here, we provide a quantitative theoretical evaluation that shows the positive net charges, which accumulate around the pore entrance due to the salt gradient, are responsible for the two observed effects: they reinforce the electric capture field, resulting in promoted molecule capture rate; and they induce cationic electroosmotic flow through the nanopore, thus significantly retarding the motion of the anionic DNA through the nanopore. Our multiphysical simulation results show that, during the polymer trapping stage, the former effect plays the major role, thus resulting in promoted DNA capture rate, while during the nanopore-penetrating stage the latter effect dominates and consequently reduces the DNA translocation speed significantly. Quantitative agreement with experimental results has been reached by further taking nanopore wall surface charges into account. PMID:23931325

Over-limiting Current and Control of Dendritic Growth by Surface Conduction in Nanopores

PubMed Central

Han, Ji-Hyung; Khoo, Edwin; Bai, Peng; Bazant, Martin Z.

2014-01-01

Understanding over-limiting current (faster than diffusion) is a long-standing challenge in electrochemistry with applications in desalination and energy storage. Known mechanisms involve either chemical or hydrodynamic instabilities in unconfined electrolytes. Here, it is shown that over-limiting current can be sustained by surface conduction in nanopores, without any such instabilities, and used to control dendritic growth during electrodeposition. Copper electrodeposits are grown in anodized aluminum oxide membranes with polyelectrolyte coatings to modify the surface charge. At low currents, uniform electroplating occurs, unaffected by surface modification due to thin electric double layers, but the morphology changes dramatically above the limiting current. With negative surface charge, growth is enhanced along the nanopore surfaces, forming surface dendrites and nanotubes behind a deionization shock. With positive surface charge, dendrites avoid the surfaces and are either guided along the nanopore centers or blocked from penetrating the membrane. PMID:25394685

The rectification of mono- and bivalent ions in single conical nanopores

NASA Astrophysics Data System (ADS)

Wei, Junzhe; Du, Guanghua; Guo, Jinlong; Li, Yaning; Liu, Wenjing; Yao, Huijun; Zhao, Jing; Wu, Ruqun; Chen, Hao; Ponomarov, Artem

2017-08-01

The polyethylene terephthalate (PET) films were irradiated with single 6.9 MeV/u 58Ni19+ ions at the Lanzhou Interdisciplinary Heavy Ion Microbeam (LIHIM), and single conical nanopores were produced by asymmetric chemical etching of the latent ion tracks. Then, the current-voltage (I-V) characteristic was measured in LiCl, NaCl, KCl, MgCl2, and CaCl2 solution at different concentrations to study the transport properties of different cations in the single conical nanopores respectively. The measured I-V data showed that the conical nanopores have rectified transportation of these cations at the applied voltage of between +2 V and -2 V. The rectification coefficient γ of the mono- and bivalent ions was determined in their solution of 0.0001-1 M measured at 1 V, the result showed that the rectification coefficient is dependent on the valence of the ions and the electrolyte solution.

Nanoporous Cyanate Ester Resins: Structure-Gas Transport Property Relationships

NASA Astrophysics Data System (ADS)

Gusakova, Kristina; Fainleib, Alexander; Espuche, Eliane; Grigoryeva, Olga; Starostenko, Olga; Gouanve, Fabrice; Boiteux, Gisèle; Saiter, Jean-Marc; Grande, Daniel

2017-04-01

This contribution addresses the relationships between the structure and gas transport properties of nanoporous thermostable cyanate ester resins (CERs) derived from polycyclotrimerization of 1,1'-bis(4-cyanatophenyl)ethane in the presence of 30 or 50 wt% of inert high-boiling temperature porogens (i.e., dimethyl- or dibutyl phthalates), followed by their quantitative removal. The nanopores in the films obtained were generated via a chemically induced phase separation route with further porogen extraction from the densely crosslinked CERs. To ensure a total desorption of the porogen moieties from the networks, an additional short-term thermal annealing at 250 °C was performed. The structure and morphology of such nanoporous CER-based films were investigated by FTIR and SEM techniques, respectively. Further, the gas transport properties of CER films were analyzed after the different processing steps, and relationships between the material structure and the main gas transport parameters were established.

Modification of electrical properties of silicon dioxide through intrinsic nano-patterns

NASA Astrophysics Data System (ADS)

Majee, Subimal; Barshilia, Devesh; Banerjee, Debashree; Kumar, Sanjeev; Mishra, Prabhash; Akhtar, Jamil

2018-05-01

The inherent network of nanopores and voids in silicon dioxide (SiO2) is generally undesirable for aspects of film quality, electrical insulation and dielectric performance. However, if we view these pores as natural nano-patterns embedded in a dielectric matrix then that opens up new vistas for exploration. The nano-pattern platform can be used to tailor electrical, optical, magnetic and mechanical properties of the carrier film. In this article we report the tunable electrical properties of thermal SiO2 thin-film achieved through utilization of the metal-nanopore network where the pores are filled with metallic Titanium (Ti). Without any intentional chemical doping, we have shown that the electrical resistivity of the oxide film can be controlled through physical filling up of the intrinsic oxide nanopores with Ti. The electrical resistivity of the composite film remains constant even after complete removal of the metal from the film surface except the pores. Careful morphological, electrical and structural analyses are carried out to establish that the presence of Ti in the nanopores play a crucial role in the observed conductive nature of the nanoporous film.

Determination by Small-angle X-ray Scattering of Pore Size Distribution in Nanoporous Track-etched Polycarbonate Membranes

NASA Astrophysics Data System (ADS)

Jonas, A. M.; Legras, R.; Ferain, E.

1998-03-01

Nanoporous track-etched membranes with narrow pore size distributions and average pore size diameters tunable from 100 to 1000 Åare produced by the chemical etching of latent tracks in polymer films after irradiation by a beam of accelerated heavy ions. Nanoporous membranes are used for highly demanding filtration purposes, or as templates to obtain metallic or polymeric nanowires (L. Piraux et al., Nucl. Instr. Meth. Phys. Res. 1997, B131, 357). Such applications call for developments in nanopore size characterization techniques. In this respect, we report on the characterization by small-angle X-ray scattering (SAXS) of nanopore size distribution (nPSD) in polycarbonate track-etched membranes. The obtention of nPSD requires inverting an ill-conditioned inhomogeneous equation. We present different numerical routes to overcome the amplification of experimental errors in the resulting solutions, including a regularization technique allowing to obtain the nPSD without a priori knowledge of its shape. The effect of deviations from cylindrical pore shape on the resulting distributions are analyzed. Finally, SAXS results are compared to results obtained by electron microscopy and conductometry.

Solid-State and Biological Nanopore for Real-Time Sensing of Single Chemical and Sequencing of DNA.

PubMed

Haque, Farzin; Li, Jinghong; Wu, Hai-Chen; Liang, Xing-Jie; Guo, Peixuan

2013-02-01

Sensitivity and specificity are two most important factors to take into account for molecule sensing, chemical detection and disease diagnosis. A perfect sensitivity is to reach the level where a single molecule can be detected. An ideal specificity is to reach the level where the substance can be detected in the presence of many contaminants. The rapidly progressing nanopore technology is approaching this threshold. A wide assortment of biomotors and cellular pores in living organisms perform diverse biological functions. The elegant design of these transportation machineries has inspired the development of single molecule detection based on modulations of the individual current blockage events. The dynamic growth of nanotechnology and nanobiotechnology has stimulated rapid advances in the study of nanopore based instrumentation over the last decade, and inspired great interest in sensing of single molecules including ions, nucleotides, enantiomers, drugs, and polymers such as PEG, RNA, DNA, and polypeptides. This sensing technology has been extended to medical diagnostics and third generation high throughput DNA sequencing. This review covers current nanopore detection platforms including both biological pores and solid state counterparts. Several biological nanopores have been studied over the years, but this review will focus on the three best characterized systems including α-hemolysin and MspA, both containing a smaller channel for the detection of single-strand DNA, as well as bacteriophage phi29 DNA packaging motor connector that contains a larger channel for the passing of double stranded DNA. The advantage and disadvantage of each system are compared; their current and potential applications in nanomedicine, biotechnology, and nanotechnology are discussed.

Solid-State and Biological Nanopore for Real-Time Sensing of Single Chemical and Sequencing of DNA

PubMed Central

Haque, Farzin; Li, Jinghong; Wu, Hai-Chen; Liang, Xing-Jie; Guo, Peixuan

2013-01-01

Sensitivity and specificity are two most important factors to take into account for molecule sensing, chemical detection and disease diagnosis. A perfect sensitivity is to reach the level where a single molecule can be detected. An ideal specificity is to reach the level where the substance can be detected in the presence of many contaminants. The rapidly progressing nanopore technology is approaching this threshold. A wide assortment of biomotors and cellular pores in living organisms perform diverse biological functions. The elegant design of these transportation machineries has inspired the development of single molecule detection based on modulations of the individual current blockage events. The dynamic growth of nanotechnology and nanobiotechnology has stimulated rapid advances in the study of nanopore based instrumentation over the last decade, and inspired great interest in sensing of single molecules including ions, nucleotides, enantiomers, drugs, and polymers such as PEG, RNA, DNA, and polypeptides. This sensing technology has been extended to medical diagnostics and third generation high throughput DNA sequencing. This review covers current nanopore detection platforms including both biological pores and solid state counterparts. Several biological nanopores have been studied over the years, but this review will focus on the three best characterized systems including α-hemolysin and MspA, both containing a smaller channel for the detection of single-strand DNA, as well as bacteriophage phi29 DNA packaging motor connector that contains a larger channel for the passing of double stranded DNA. The advantage and disadvantage of each system are compared; their current and potential applications in nanomedicine, biotechnology, and nanotechnology are discussed. PMID:23504223

Biocompatibility of nanoporous alumina membranes for immunoisolation

PubMed Central

La Flamme, Kristen E.; Popat, Ketul C.; Leoni, Lara; Markiewicz, Erica; LaTempa, Thomas J.; Roman, Brian B.; Grimes, Craig A.; Desai, Tejal A.

2011-01-01

Cellular immunoisolation using semi-permeable barriers has been investigated over the past several decades as a promising treatment approach for diseases such as Parkinson’s, Alzheimer’s, and Type 1 diabetes. Typically, polymeric membranes are used for immunoisolation applications; however, recent advances in technology have led to the development of more robust membranes that are able to more completely meet the requirements for a successful immunoisolation device, including well controlled pore size, chemical and mechanical stability, non-biodegradability, and biocompatibility with both the graft tissue as well as the host. It has been shown previously that nanoporous alumina biocapsules can act effectively as immunoisolation devices, and support the viability and functionality of encapsulated β cells. The aim of this investigation was to assess the biocompatibility of the material with host tissue. The cytotoxicity of the capsule, as well as its ability to activate complement and inflammation was studied. Further, the effects of PEG-modification on the tissue response to implanted capsules were studied. Our results have shown that the device is non-toxic and does not induce significant complement activation. Further, in vivo work has demonstrated that implantation of these capsules into the peritoneal cavity of rats induces a transient inflammatory response, and that PEG is useful in minimizing the host response to the material. PMID:17335895

Cells exposed to nanosecond electrical pulses exhibit biomarkers of mechanical stress

NASA Astrophysics Data System (ADS)

Roth, Caleb C.; Barnes, Ronald A.; Ibey, Bennett L.; Beier, Hope T.; Moen, Erick K.; Glickman, Randolph D.

2015-03-01

Exposure of cells to very short (<1 μs) electric pulses in the megavolt/meter range have been shown to cause disruption of the plasma membrane. This disruption is often characterized by the formation of numerous small pores (<2 nm in diameter) in the plasma membrane that last for several minutes, allowing the flow of ions into the cell. These small pores are called nanopores and the resulting damage to the plasma membrane is referred to as nanoporation. Nanosecond electrical pulse (nsEP) exposure can impart many different stressors on a cell, including electrical, electro-chemical, and mechanical stress. Thus, nsEP exposure is not a "clean" insult, making determination of the mechanism of nanoporation quite difficult. We hypothesize that nsEP exposure creates acoustic shock waves capable of causing nanoporation. Microarray analysis of primary adult human dermal fibroblasts (HDFa) exposed to nsEP, indicated several genes associated with mechanical stress were selectively upregulated 4 h post exposure. The idea that nanoporation is caused by external mechanical force from acoustic shock waves has, to our knowledge, not been investigated. This work will critically challenge the existing paradigm that nanoporation is caused solely by an electric-field driven event and could provide the basis for a plausible explanation for electroporation.

Chemical Reaction Equilibrium in Nanoporous Materials: NO Dimerization Reaction in Carbon Slit Nanopores

DTIC Science & Technology

2006-09-01

hi 0T − Tsi 0T , 10 where the molar enthalpy, hi 0T, and the molar entropy, si 0T, may be expressed as hi 0T = Hfi Tr + Tr T cpi 0...TdT , 11 si 0T = si 0Tr + Tr T cpi 0 T T dT . 12 In Eqs. 11 and 12, Hfi Tr is the enthalpy of formation of species i at the

Water soluble nanoporous nanoparticle for in vivo targeted drug delivery and controlled release in B cells tumor context

NASA Astrophysics Data System (ADS)

de Angelis, F.; Pujia, A.; Falcone, C.; Iaccino, E.; Palmieri, C.; Liberale, C.; Mecarini, F.; Candeloro, P.; Luberto, L.; de Laurentiis, A.; Das, G.; Scala, G.; di Fabrizio, E.

2010-10-01

Multitasking nanoparticles are gaining great attention for smart drug delivery systems. The exploration of the nano-scale opens new concrete opportunities for revealing new properties and undiscovered cell-particle interactions. Here we present a biodegradable nanoporous silicon nanoparticle that can be successfully employed for in vivo targeted drug delivery and sustained release. The bare nanoporous nanocarriers can be accurately designed and fabricated with an effective control of porosity, surface chemistry and particle size, up to a few nm. The proposed nanoparticles exhibit several remarkable features including high payload, biodegradability, no toxicity, and multiple loading in water without the need of additional chemical reagents at room temperature. The targeting strategy is based on phage display technology that was successfully used to discover cell surface binding peptide for murine B lymphoma A20 cell line. The peptide used in combination with the nanoporous nanoparticles allows an efficient in vivo targeting, a sustained release and a sensible therapeutic effect.Multitasking nanoparticles are gaining great attention for smart drug delivery systems. The exploration of the nano-scale opens new concrete opportunities for revealing new properties and undiscovered cell-particle interactions. Here we present a biodegradable nanoporous silicon nanoparticle that can be successfully employed for in vivo targeted drug delivery and sustained release. The bare nanoporous nanocarriers can be accurately designed and fabricated with an effective control of porosity, surface chemistry and particle size, up to a few nm. The proposed nanoparticles exhibit several remarkable features including high payload, biodegradability, no toxicity, and multiple loading in water without the need of additional chemical reagents at room temperature. The targeting strategy is based on phage display technology that was successfully used to discover cell surface binding peptide for murine B lymphoma A20 cell line. The peptide used in combination with the nanoporous nanoparticles allows an efficient in vivo targeting, a sustained release and a sensible therapeutic effect. Electronic supplementary information (ESI) available: Nanoparticles fabrication; payload evaluation; dissolution and release profiles; multivalent loading; targeting specifity on A20 Cells; cell cycle analysis; in vitro cytotoxicity assay; in vivo cytotoxicity assay. See DOI: 10.1039/c0nr00161a

Charge-specific size-dependent separation of water-soluble organic molecules by fluorinated nanoporous networks

NASA Astrophysics Data System (ADS)

Byun, Jeehye; Patel, Hasmukh A.; Thirion, Damien; Yavuz, Cafer T.

2016-11-01

Molecular architecture in nanoscale spaces can lead to selective chemical interactions and separation of species with similar sizes and functionality. Substrate specific sorbent chemistry is well known through highly crystalline ordered structures such as zeolites, metal organic frameworks and widely available nanoporous carbons. Size and charge-dependent separation of aqueous molecular contaminants, on the contrary, have not been adequately developed. Here we report a charge-specific size-dependent separation of water-soluble molecules through an ultra-microporous polymeric network that features fluorines as the predominant surface functional groups. Treatment of similarly sized organic molecules with and without charges shows that fluorine interacts with charges favourably. Control experiments using similarly constructed frameworks with or without fluorines verify the fluorine-cation interactions. Lack of a σ-hole for fluorine atoms is suggested to be responsible for this distinct property, and future applications of this discovery, such as desalination and mixed matrix membranes, may be expected to follow.

Charge-specific size-dependent separation of water-soluble organic molecules by fluorinated nanoporous networks

PubMed Central

Byun, Jeehye; Patel, Hasmukh A.; Thirion, Damien; Yavuz, Cafer T.

2016-01-01

Molecular architecture in nanoscale spaces can lead to selective chemical interactions and separation of species with similar sizes and functionality. Substrate specific sorbent chemistry is well known through highly crystalline ordered structures such as zeolites, metal organic frameworks and widely available nanoporous carbons. Size and charge-dependent separation of aqueous molecular contaminants, on the contrary, have not been adequately developed. Here we report a charge-specific size-dependent separation of water-soluble molecules through an ultra-microporous polymeric network that features fluorines as the predominant surface functional groups. Treatment of similarly sized organic molecules with and without charges shows that fluorine interacts with charges favourably. Control experiments using similarly constructed frameworks with or without fluorines verify the fluorine-cation interactions. Lack of a σ-hole for fluorine atoms is suggested to be responsible for this distinct property, and future applications of this discovery, such as desalination and mixed matrix membranes, may be expected to follow. PMID:27830697

Investigation of bioactivity and cell effects of nano-porous sol-gel derived bioactive glass film

NASA Astrophysics Data System (ADS)

Ma, Zhijun; Ji, Huijiao; Hu, Xiaomeng; Teng, Yu; Zhao, Guiyun; Mo, Lijuan; Zhao, Xiaoli; Chen, Weibo; Qiu, Jianrong; Zhang, Ming

2013-11-01

In orthopedic surgery, bioactive glass film coating is extensively studied to improve the synthetic performance of orthopedic implants. A lot of investigations have confirmed that nano-porous structure in bioactive glasses can remarkably improve their bioactivity. Nevertheless, researches on preparation of nano-porous bioactive glasses in the form of film coating and their cell response activities are scarce. Herein, we report the preparation of nano-porous bioactive glass film on commercial glass slide based on a sol-gel technique, together with the evaluation of its in vitro bioactivity through immersion in simulated body fluid and monitoring the precipitation of apatite-like layer. Cell responses of the samples, including attachment, proliferation and osteogenic differentiation, were also investigated using BMSCS (bone marrow derived mesenchymal stem cells) as a model. The results presented here provide some basic information on structural influence of bioactive glass film on the improvement of bioactivity and cellular effects.

A novel material screening platform for nanoporous gold-based neural electrodes

NASA Astrophysics Data System (ADS)

Chapman, Christopher Abbott Reece

Neural-electrical interfaces have emerged in the past decades as a promising modality to facilitate the understanding of the electropathophysiology of neurological disorders as well as the normal functioning of the central nervous system, and enable the treatment of neurological defects through electrical stimulation or electrically-controlled drug delivery. However, chronically implanted electrodes face a myriad of design challenges, including their coupling to neural tissue (biocompatibility), small form factor requirement, and their electrical properties (maintaining a low electrical impedance). Planar electrode materials such as planar platinum and gold experience a large increase in electrical impedance when electrode dimensions are reduced to increase spatial resolution of neural recordings. A decrease in electrode surface area reduces the total capacitance of the electrode double layer resulting in an increase in electrode impedance. This high impedance can reduce the signal amplitude and increase the thermal noise, resulting in degradation of signal-to-noise ratio. Conventionally, this increase in electrical impedance at small electrode dimensions has been mitigated by coatings with rough morphologies such as platinum black, conducting polymers, and titanium nitride. Porous surfaces have high effective surface area enabling low impedance at small electrode dimensions. However, achieving long-term stability of cellular coupling to the electrode surface has remained difficult. Designing electrodes that can physically couple with neurons successfully and maintain low impedance at small electrode dimensions necessitates consideration of novel electrode coatings, such as carbon nanotubes and gold nanopillars. Another promising material, and focus of this proposal, is thin film nanoporous gold (np-Au). Nanoporous gold is a promising material for addressing these limitations because of its inherently large effective surface area allows for lower impedances at small form factors, and its modifiable surface morphology can be used to control cell-electrode coupling. Additionally, thin film nanoporous gold is fabricated by traditional microfabrication methods, and thus can be directly adopted by the current state-of-the-art neural electrode fabrication processes. All these properties make thin film nanoporous gold a promising candidate for use in neural electrode surfaces. This dissertation seeks to characterize both the morphological and the electrical response of neural cells to thin film nanoporous gold morphologies using an in vitro electrode morphology screening platform. The specific aims for this proposal are to: (i) develop a electrode morphology library that displays varying topographies to study structure-property relationships of thin film nanoporous gold and cellular response, (ii) characterize neural cell response to identified nanoporous gold topographies that reduce adverse tissue response in vitro, and (iii) develop an electrophysiology platform to characterize neural coupling to each identified nanoporous gold topography.

Nanoporous gold film based SPR sensors for trace chemical detection

NASA Astrophysics Data System (ADS)

Wang, Li; Gong, Xiaoqing; Wan, Xiumei; Lu, Dan-feng; Qi, Zhi-mei

2017-02-01

Thin films of nanoporous gold (NPG) have both localized and propagating surface plasmon resonance (SPR) effects. The propagating SPR effect of NPG film combined with its huge internal surface area makes it applicable as an evanescent wave sensor with high sensitivity. In this work, NPG films with controlled thicknesses were fabricated on glass substrates by sputtering deposition of AuAg films followed by dealloying in nitric acid. By using of the NPG films as the sensing layer, a broadband wavelength-interrogated SPR sensor was prepared for chemical and biological detection. The propagating SPR absorption band in the visible-near infrared region was clearly observed upon exposure of the NPG film to air, and this band was detected to move to longer wavelengths in response to adsorption of molecules within the NPG film. Simulations based on Fresnel equations combined with Bruggeman approximation were carried out for optimizing the propagating SPR property of NPG film. The sensor's performance was investigated using both bisphenol A (BPA) and lead (II) ions as analytes. According to the experimental results, the detection limits of the sensor are 5 nmol·L-1 for BPA and 1 nmol·L-1 for lead (II) ions. The work demonstrated the outstanding applicability of the NPG film based SPR sensor for sensitive environmental monitoring.

Metal–Organic Framework Thin Film Coated Optical Fiber Sensors: A Novel Waveguide-Based Chemical Sensing Platform

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Ki-Joong; Lu, Ping; Culp, Jeffrey T.

Integration of optical fiber with sensitive thin films offers great potential for the realization of novel chemical sensing platforms. In this study, we present a simple design strategy and high performance of nanoporous metal–organic framework (MOF) based optical gas sensors, which enables detection of a wide range of concentrations of small molecules based upon extremely small differences in refractive indices as a function of analyte adsorption within the MOF framework. Thin and compact MOF films can be uniformly formed and tightly bound on the surface of etched optical fiber through a simple solution method which is critical for manufacturability ofmore » MOF-based sensor devices. The resulting sensors show high sensitivity/selectivity to CO 2 gas relative to other small gases (H 2, N 2, O 2, and CO) with rapid (< tens of seconds) response time and excellent reversibility, which can be well correlated to the physisorption of gases into a nanoporous MOF. We propose a refractive index based sensing mechanism for the MOF-integrated optical fiber platform which results in an amplification of inherent optical absorption present within the MOF-based sensing layer with increasing values of effective refractive index associated with adsorption of gases.« less

Metal–Organic Framework Thin Film Coated Optical Fiber Sensors: A Novel Waveguide-Based Chemical Sensing Platform

DOE PAGES

Kim, Ki-Joong; Lu, Ping; Culp, Jeffrey T.; ...

2018-01-18

Integration of optical fiber with sensitive thin films offers great potential for the realization of novel chemical sensing platforms. In this study, we present a simple design strategy and high performance of nanoporous metal–organic framework (MOF) based optical gas sensors, which enables detection of a wide range of concentrations of small molecules based upon extremely small differences in refractive indices as a function of analyte adsorption within the MOF framework. Thin and compact MOF films can be uniformly formed and tightly bound on the surface of etched optical fiber through a simple solution method which is critical for manufacturability ofmore » MOF-based sensor devices. The resulting sensors show high sensitivity/selectivity to CO 2 gas relative to other small gases (H 2, N 2, O 2, and CO) with rapid (< tens of seconds) response time and excellent reversibility, which can be well correlated to the physisorption of gases into a nanoporous MOF. We propose a refractive index based sensing mechanism for the MOF-integrated optical fiber platform which results in an amplification of inherent optical absorption present within the MOF-based sensing layer with increasing values of effective refractive index associated with adsorption of gases.« less

Interfacial Engineering of Nanoporous Architectures in Ga2O3 Film toward Self-Aligned Tubular Nanostructure with an Enhanced Photocatalytic Activity on Water Splitting.

PubMed

Shrestha, Nabeen K; Bui, Hoa Thi; Lee, Taegweon; Noh, Yong-Young

2018-04-17

The present work demonstrates the formation of self-aligned nanoporous architecture of gallium oxide by anodization of gallium metal film controlled at -15 °C in aqueous electrolyte consisting of phosphoric acid. SEM examination of the anodized film reveals that by adding ethylene glycol to the electrolyte and optimizing the ratio of phosphoric acid and water, chemical etching at the oxide/electrolyte interfaces can be controlled, leading to the formation of aligned nanotubular oxide structures with closed bottom. XPS analysis confirms the chemical composition of the oxide film as Ga 2 O 3 . Further, XRD and SAED examination reveals that the as-synthesized nanotubular structure is amorphous, and can be crystallized to β-Ga 2 O 3 phase by annealing the film at 600 °C. The nanotubular structured film, when used as photoanode for photoelectrochemical splitting of water, achieved a higher photocurrent of about two folds than that of the nanoporous film, demonstrating the rewarding effect of the nanotubular structure. In addition, the work also demonstrates the formation of highly organized nonporous Ga 2 O 3 structure on a nonconducting glass substrate coated with thin film of Ga-metal, highlighting that the current approach can be extended for the formation of self-organized nanoporous Ga 2 O 3 thin film even on nonconducting flexible substrates.

Nanoscale dynamics of Joule heating and bubble nucleation in a solid-state nanopore.

PubMed

Levine, Edlyn V; Burns, Michael M; Golovchenko, Jene A

2016-01-01

We present a mathematical model for Joule heating of an electrolytic solution in a nanopore. The model couples the electrical and thermal dynamics responsible for rapid and extreme superheating of the electrolyte within the nanopore. The model is implemented numerically with a finite element calculation, yielding a time and spatially resolved temperature distribution in the nanopore region. Temperatures near the thermodynamic limit of superheat are predicted to be attained just before the explosive nucleation of a vapor bubble is observed experimentally. Knowledge of this temperature distribution enables the evaluation of related phenomena including bubble nucleation kinetics, relaxation oscillation, and bubble dynamics.

Can Nanofluidic Chemical Release Enable Fast, High Resolution Neurotransmitter-Based Neurostimulation?

PubMed

Jones, Peter D; Stelzle, Martin

2016-01-01

Artificial chemical stimulation could provide improvements over electrical neurostimulation. Physiological neurotransmission between neurons relies on the nanoscale release and propagation of specific chemical signals to spatially-localized receptors. Current knowledge of nanoscale fluid dynamics and nanofluidic technology allows us to envision artificial mechanisms to achieve fast, high resolution neurotransmitter release. Substantial technological development is required to reach this goal. Nanofluidic technology-rather than microfluidic-will be necessary; this should come as no surprise given the nanofluidic nature of neurotransmission. This perspective reviews the state of the art of high resolution electrical neuroprostheses and their anticipated limitations. Chemical release rates from nanopores are compared to rates achieved at synapses and with iontophoresis. A review of microfluidic technology justifies the analysis that microfluidic control of chemical release would be insufficient. Novel nanofluidic mechanisms are discussed, and we propose that hydrophobic gating may allow control of chemical release suitable for mimicking neurotransmission. The limited understanding of hydrophobic gating in artificial nanopores and the challenges of fabrication and large-scale integration of nanofluidic components are emphasized. Development of suitable nanofluidic technology will require dedicated, long-term efforts over many years.

DNA Sequence-Dependent Ionic Currents in Ultra-Small Solid-State Nanopores†

PubMed Central

Comer, Jeffrey

2016-01-01

Measurements of ionic currents through nanopores partially blocked by DNA have emerged as a powerful method for characterization of the DNA nucleotide sequence. Although the effect of the nucleotide sequence on the nanopore blockade current has been experimentally demonstrated, prediction and interpretation of such measurements remain a formidable challenge. Using atomic resolution computational approaches, here we show how the sequence, molecular conformation, and pore geometry affect the blockade ionic current in model solid-state nanopores. We demonstrate that the blockade current from a DNA molecule is determined by the chemical identities and conformations of at least three consecutive nucleotides. We find the blockade currents produced by the nucleotide triplets to vary considerably with their nucleotide sequence despite having nearly identical molecular conformations. Encouragingly, we find blockade current differences as large as 25% for single-base substitutions in ultra small (1.6 nm × 1.1 nm cross section; 2 nm length) solid-state nanopores. Despite the complex dependence of the blockade current on the sequence and conformation of the DNA triplets, we find that, under many conditions, the number of thymine bases is positively correlated with the current, whereas the number of purine bases and the presence of both purine and pyrimidines in the triplet are negatively correlated with the current. Based on these observations, we construct a simple theoretical model that relates the ion current to the base content of a solid-state nanopore. Furthermore, we show that compact conformations of DNA in narrow pores provide the greatest signal-to-noise ratio for single base detection, whereas reduction of the nanopore length increases the ionic current noise. Thus, the sequence dependence of nanopore blockade current can be theoretically rationalized, although the predictions will likely need to be customized for each nanopore type. PMID:27103233

Facile fabrication of highly controllable gating systems based on the combination of inverse opal structure and dynamic covalent chemistry.

PubMed

Wang, Chen; Yang, Haowei; Tian, Li; Wang, Shiqiang; Gao, Ning; Zhang, Wanlin; Wang, Peng; Yin, Xianpeng; Li, Guangtao

2017-06-01

A three-dimensional (3D) inverse opal with periodic and porous structures has shown great potential for applications not only in optics and optoelectronics, but also in functional membranes. In this work, the benzaldehyde group was initially introduced into a 3D nanoporous inverse opal, serving as a platform for fabricating functional membranes. By employing the dynamic covalent approach, a highly controllable gating system was facilely fabricated to achieve modulable and reversible transport features. It was found that the physical/chemical properties and pore size of the gating system could easily be regulated through post-modification with amines. As a demonstration, the gated nanopores were modified with three kinds of amines to control the wettability, surface charge and nanopore size which in turn was exploited to achieve selective mass transport, including hydrophobic molecules, cations and anions, and the transport with respect to the physical steric hindrance. In particular, the gating system showed extraordinary reversibility and could recover to its pristine state by simply changing pH values. Due to the unlimited variety provided by the Schiff base reaction, the inverse opal described here exhibits a significant extendibility and could be easily post-modified with stimuli-responsive molecules for special purposes. Furthermore, this work can be extended to employ other dynamic covalent routes, for example Diels-Alder, ester exchange and disulfide exchange-based routes.

Nanogeochemistry: Size-dependent mineral-fluid interface chemistry

NASA Astrophysics Data System (ADS)

Wang, Y.

2012-12-01

Nanostructures and nanometer mineral phases, both widely present in geologic materials, can potentially affect many geochemical processes. It is known that at nanometer scales a material tends to exhibit chemical properties distinct from the corresponding bulk phase. Understanding of this size-dependent property change will help us to bridge the existing knowledge gap between the molecular level understanding and the macro-scale laboratory/field observations of a geochemical process. In this presentation, I will review of the recent progresses in nanoscience and provide a perspective on how these progresses can potentially impact geochemical studies. My presentation will be focused the following areas: (1) the characterization of nanostructures in natural systems, (2) the study of fluids and chemical species in nanoconfinement, (3) the effects of nanopores on geochemical reaction and mass transfers, and (4) the use nanostructured materials for environmental management. I will demonstrate that the nanopore confinement can significantly modify geochemical reactions in porous geologic media. As the pore size is reduced to a few nanometers, the difference between surface acidity constants of a mineral (pK2 - pK1) decreases, giving rise to a higher surface charge density on a nanopore surface than that on an unconfined mineral-water interface. The change in surface acidity constants results in a shift of ion sorption edges and enhances ion sorption on nanopore surfaces. This effect causes preferential enrichment of trace elements in nanopores. I will then discuss the implications of this emergent nanometer-scale property to radionuclide transport and carbon dioxide storage in geologic media. This work was performed at Sandia National Laboratories, which is a multiprogram laboratory operated by Sandia Corporation, a Lockheed-Martin Company, for the DOE under contract DE-AC04-94AL8500.

Cesium-Induced Ionic Conduction through a Single Nanofluidic Pore Modified with Calixcrown Moieties.

PubMed

Ali, Mubarak; Ahmed, Ishtiaq; Ramirez, Patricio; Nasir, Saima; Cervera, Javier; Mafe, Salvador; Niemeyer, Christof M; Ensinger, Wolfgang

2017-09-12

We demonstrate experimentally and theoretically a nanofluidic device for the selective recognition of the cesium ion by exploiting host-guest interactions inside confined geometry. For this purpose, a host molecule, i.e., the amine-terminated p-tert-butylcalix[4]arene-crown (t-BuC[4]C-NH 2 ), is successfully synthesized and functionalized on the surface of a single conical nanopore fabricated in a poly(ethylene terephthalate) (PET) membrane through carbodiimide coupling chemistry. On exposure to the cesium cation, the t-BuC[4]C-Cs + complex is formed through host-guest interaction, leading to the generation of positive fixed charges on the pore surface. The asymmetrical distribution of these groups along the conical nanopore leads to the electrical rectification observed in the current-voltage (I-V) curve. On the contrary, other alkali cations are not able to induce any significant change in the rectification characteristics of the nanopore. The success of the chemical modification is monitored from the changes in the electrical readout of the nanopore. Theoretical results based on the Nernst-Planck and Poisson equations further demonstrate the validity of the experimental approach to the cesium-induced ionic conduction of the nanopore.

Capture and alignment of phi29 viral particles in sub-40 nanometer porous alumina membranes.

PubMed

Moon, Jeong-Mi; Akin, Demir; Xuan, Yi; Ye, Peide D; Guo, Peixuan; Bashir, Rashid

2009-02-01

Bacteriophage phi29 virus nanoparticles and its associated DNA packaging nanomotor can provide for novel possibilities towards the development of hybrid bio-nano structures. Towards the goal of interfacing the phi29 viruses and nanomotors with artificial micro and nanostructures, we fabricated nanoporous Anodic Aluminum Oxide (AAO) membranes with pore size of 70 nm and shrunk the pores to sub 40 nm diameter using atomic layer deposition (ALD) of Aluminum Oxide. We were able to capture and align particles in the anodized nanopores using two methods. Firstly, a functionalization and polishing process to chemically attach the particles in the inner surface of the pores was developed. Secondly, centrifugation of the particles was utilized to align them in the pores of the nanoporous membranes. In addition, when a mixture of empty capsids and packaged particles was centrifuged at specific speeds, it was found that the empty capsids deform and pass through 40 nm diameter pores whereas the particles packaged with DNA were mainly retained at the top surface of the nanoporous membranes. Fluorescence microscopy was used to verify the selective filtration of empty capsids through the nanoporous membranes.

Spontaneous Transport of Single-Stranded DNA through Graphene-MoS2 Heterostructure Nanopores.

PubMed

Luan, Binquan; Zhou, Ruhong

2018-04-24

The effective transport of a single-stranded DNA (ssDNA) molecule through a solid-state nanopore is essential to the future success of high-throughput and low-cost DNA sequencing. Compatible with current electric sensing technologies, here, we propose and demonstrate by molecular dynamics simulations the ssDNA transport through a quasi-two-dimensional nanopore in a heterostructure stacked together with different 2D materials, such as graphene and molybdenum disulfide (MoS 2 ). Due to different chemical potentials, U, of DNA bases on different 2D materials, it is energetically favorable for a ssDNA molecule to move from the low- U MoS 2 surface to the high- U graphene surface through a nanopore. With the proper attraction between the negatively charged phosphate group in each nucleotide and the positively charged Mo atoms exposed on the pore surface, the ssDNA molecule can be temporarily seized and released thereafter through a thermal activation, that is, a slow and possible nucleotide-by-nucleotide transport. A theoretical formulation is then developed for the free energy of the ssDNA transiting a heterostructure nanopore to properly characterize the non-equilibrium stick-slip-like motion of a ssDNA molecule.

Fluoride-induced modulation of ionic transport in asymmetric nanopores functionalized with "caged" fluorescein moieties.

PubMed

Ali, Mubarak; Ahmed, Ishtiaq; Ramirez, Patricio; Nasir, Saima; Cervera, Javier; Niemeyer, Christof M; Ensinger, Wolfgang

2016-04-28

We demonstrate experimentally and theoretically a nanofluidic fluoride sensing device based on a single conical pore functionalized with "caged" fluorescein moieties. The nanopore functionalization is based on an amine-terminated fluorescein whose phenolic hydroxyl groups are protected with tert-butyldiphenylsilyl (TBDPS) moieties. The protected fluorescein (Fcn-TBDPS-NH2) molecules are then immobilized on the nanopore surface via carbodiimide coupling chemistry. Exposure to fluoride ions removes the uncharged TBDPS moieties due to the fluoride-promoted cleavage of the silicon-oxygen bond, leading to the generation of negatively charged groups on the fluorescein moieties immobilized onto the pore surface. The asymmetrical distribution of these groups along the conical nanopore leads to the electrical rectification observed in the current-voltage (I-V) curve. On the contrary, other halides and anions are not able to induce any significant ionic rectification in the asymmetric pore. In each case, the success of the chemical functionalization and deprotection reactions is monitored through the changes observed in the I-V curves before and after the specified reaction step. The theoretical results based on the Nernst-Planck and Poisson equations further demonstrate the validity of an experimental approach to fluoride-induced modulation of nanopore current rectification behaviour.

2D nanoporous membrane for cation removal from water: Effects of ionic valence, membrane hydrophobicity, and pore size

NASA Astrophysics Data System (ADS)

Köhler, Mateus Henrique; Bordin, José Rafael; Barbosa, Marcia C.

2018-06-01

Using molecular dynamic simulations, we show that single-layers of molybdenum disulfide (MoS2) and graphene can effectively reject ions and allow high water permeability. Solutions of water and three cations with different valencies (Na+, Zn2+, and Fe3+) were investigated in the presence of the two types of membranes, and the results indicate a high dependence of the ion rejection on the cation charge. The associative characteristic of ferric chloride leads to a high rate of ion rejection by both nanopores, while the monovalent sodium chloride induces lower rejection rates. Particularly, MoS2 shows 100% of Fe3+ rejection for all pore sizes and applied pressures. On the other hand, the water permeation does not vary with the cation valence, having dependence only with the nanopore geometric and chemical characteristics. This study helps us to understand the fluid transport through a nanoporous membrane, essential for the development of new technologies for the removal of pollutants from water.

2D nanoporous membrane for cation removal from water: Effects of ionic valence, membrane hydrophobicity, and pore size.

PubMed

Köhler, Mateus Henrique; Bordin, José Rafael; Barbosa, Marcia C

2018-06-14

Using molecular dynamic simulations, we show that single-layers of molybdenum disulfide (MoS 2 ) and graphene can effectively reject ions and allow high water permeability. Solutions of water and three cations with different valencies (Na + , Zn 2+ , and Fe 3+ ) were investigated in the presence of the two types of membranes, and the results indicate a high dependence of the ion rejection on the cation charge. The associative characteristic of ferric chloride leads to a high rate of ion rejection by both nanopores, while the monovalent sodium chloride induces lower rejection rates. Particularly, MoS 2 shows 100% of Fe 3+ rejection for all pore sizes and applied pressures. On the other hand, the water permeation does not vary with the cation valence, having dependence only with the nanopore geometric and chemical characteristics. This study helps us to understand the fluid transport through a nanoporous membrane, essential for the development of new technologies for the removal of pollutants from water.

Nonfaradaic nanoporous electrochemistry for conductometry at high electrolyte concentration.

PubMed

Bae, Je Hyun; Kang, Chung Mu; Choi, Hyoungseon; Kim, Beom Jin; Jang, Woohyuk; Lim, Sung Yul; Kim, Hee Chan; Chung, Taek Dong

2015-02-17

Nanoporous electrified surfaces create a unique nonfaradaic electrochemical behavior that is sensitively influenced by pore size, morphology, ionic strength, and electric field modulation. Here, we report the contributions of ion concentration and applied ac frequency to the electrode impedance through an electrical double layer overlap and ion transport along the nanopores. Nanoporous Pt with uniform pore size and geometry (L2-ePt) responded more sensitively to conductivity changes in aqueous solutions than Pt black with poor uniformity despite similar real surface areas and enabled the previously difficult quantitative conductometry measurements at high electrolyte concentrations. The nanopores of L2-ePt were more effective in reducing the electrode impedance and exhibited superior linear responses to not only flat Pt but also Pt black, leading to successful conductometric detection in ion chromatography without ion suppressors and at high ionic strengths.

Enhanced piezoelectric output of NiO/nanoporous GaN by suppression of internal carrier screening

NASA Astrophysics Data System (ADS)

Waseem, Aadil; Jeong, Dae Kyung; Johar, Muhammad Ali; Kang, Jin-Ho; Ha, Jun-Seok; Key Lee, June; Ryu, Sang-Wan

2018-06-01

The efficiency of piezoelectric nanogenerators (PNGs) significantly depends on the free carrier concentration of semiconductors. In the presence of a mechanical stress, piezoelectric charges are generated at both ends of the PNG, which are rapidly screened by the free carriers. The screening effect rapidly decreases the piezoelectric output within fractions of a second. In this study, the piezoelectric outputs of bulk- and nanoporous GaN-based heterojunction PNGs are compared. GaN thin films were epitaxially grown on sapphire substrates using metal organic chemical vapor deposition. Nanoporous GaN was fabricated using electrochemical etching, depleted of free carriers owing to the surface Fermi-level pinning. A highly resistive NiO thin film was deposited on bulk- and nanoporous GaN using radio frequency magnetron sputter. The NiO/nanoporous GaN PNG (NPNG) under a periodic compressive stress of 4 MPa exhibited an output voltage and current of 0.32 V and 1.48 μA cm‑2, respectively. The output voltage and current of the NiO/thin film-GaN PNG (TPNG) were three and five times smaller than those of the NPNG, respectively. Therefore, the high-resistivity of NiO and nanoporous GaN depleted by the Fermi-level pinning are advantageous and provide a better piezoelectric performance of the NPNG, compared with that of the TPNG.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Devkota, Jagannath; Kim, Ki-Joong; Ohodnicki, Paul R.

The integration of nanoporous materials such as metal organic frameworks (MOFs) with sensitive transducers can result in robust sensing platforms for monitoring gases and chemical vapors for a range of applications.

Bulk synthesis of nanoporous palladium and platinum powders

DOEpatents

Robinson, David B [Fremont, CA; Fares, Stephen J [Pleasanton, CA; Tran, Kim L [Livermore, CA; Langham, Mary E [Pleasanton, CA

2012-04-17

Disclosed is a method for providing nanoporous palladium and platinum powders. These materials were synthesized on milligram to gram scales by chemical reduction of tetrahalo-complexes with ascorbate in a concentrated aqueous surfactant at temperatures between -20.degree. C. and 30.degree. C. The prepared particles have diameters of approximately 50 nm, wherein each particle is perforated by pores having diameters of approximately 3 nm, as determined by electron tomography. These materials are of potential value for hydrogen and electrical charge storage applications.

Flow-through pretreatment of lignocellulosic biomass with inorganic nanoporous membranes

DOEpatents

Bhave, Ramesh R.; Lynd, Lee; Shao, Xiongjun

2018-04-03

A process for the pretreatment of lignocellulosic biomass is provided. The process generally includes flowing water through a pretreatment reactor containing a bed of particulate ligno-cellulosic biomass to produce a pressurized, high-temperature hydrolyzate exit stream, separating solubilized compounds from the hydrolyzate exit stream using an inorganic nanoporous membrane element, fractionating the retentate enriched in solubilized organic components and recycling the permeate to the pretreatment reactor. The pretreatment process provides solubilized organics in concentrated form for the subsequent conversion into biofuels and other chemicals.

Bulk synthesis of nanoporous palladium and platinum powders

DOEpatents

Robinson, David B; Fares, Stephen J; Tran, Kim L; Langham, Mary E

2014-04-15

Disclosed is a method for providing nanoporous palladium and platinum powders. These materials were synthesized on milligram to gram scales by chemical reduction of tetrahalo-complexes with ascorbate in a concentrated aqueous surfactant at temperatures between -20.degree. C. and 30.degree. C. The prepared particles have diameters of approximately 50 nm, wherein each particle is perforated by pores having diameters of approximately 3 nm, as determined by electron tomography. These materials are of potential value for hydrogen and electrical charge storage applications.

The Molecular Design of Active Sites in Nanoporous Materials for Sustainable Catalysis.

PubMed

Chapman, Stephanie; Potter, Matthew E; Raja, Robert

2017-12-02

At the forefront of global development, the chemical industry is being confronted by a growing demand for products and services, but also the need to provide these in a manner that is sustainable in the long-term. In facing this challenge, the industry is being revolutionised by advances in catalysis that allow chemical transformations to be performed in a more efficient and economical manner. To this end, molecular design, facilitated by detailed theoretical and empirical studies, has played a pivotal role in creating highly-active and selective heterogeneous catalysts. In this review, the industrially-relevant Beckmann rearrangement is presented as an exemplar of how judicious characterisation and ab initio experiments can be used to understand and optimise nanoporous materials for sustainable catalysis.

Ultrathin gas permeable oxide membranes for chemical sensing: Nanoporous Ta 2O 5 test study

DOE PAGES

Imbault, Alexander; Wang, Yue; Kruse, Peter; ...

2015-09-25

Conductometric gas sensors made of gas permeable metal oxide ultrathin membranes can combine the functions of a selective filter, preconcentrator, and sensing element and thus can be particularly promising for the active sampling of diluted analytes. Here we report a case study of the electron transport and gas sensing properties of such a membrane made of nanoporous Ta 2O 5. These membranes demonstrated a noticeable chemical sensitivity toward ammonia, ethanol, and acetone at high temperatures above 400 °C. Furthermore, different from traditional thin films, such gas permeable, ultrathin gas sensing elements can be made suspended enabling advanced architectures of ultrasensitivemore » analytical systems operating at high temperatures and in harsh environments.« less

Sustained, Controlled and Stimuli-Responsive Drug Release Systems Based on Nanoporous Anodic Alumina with Layer-by-Layer Polyelectrolyte

NASA Astrophysics Data System (ADS)

Porta-i-Batalla, Maria; Eckstein, Chris; Xifré-Pérez, Elisabet; Formentín, Pilar; Ferré-Borrull, J.; Marsal, Lluis F.

2016-08-01

Controlled drug delivery systems are an encouraging solution to some drug disadvantages such as reduced solubility, deprived biodistribution, tissue damage, fast breakdown of the drug, cytotoxicity, or side effects. Self-ordered nanoporous anodic alumina is an auspicious material for drug delivery due to its biocompatibility, stability, and controllable pore geometry. Its use in drug delivery applications has been explored in several fields, including therapeutic devices for bone and dental tissue engineering, coronary stent implants, and carriers for transplanted cells. In this work, we have created and analyzed a stimuli-responsive drug delivery system based on layer-by-layer pH-responsive polyelectrolyte and nanoporous anodic alumina. The results demonstrate that it is possible to control the drug release using a polyelectrolyte multilayer coating that will act as a gate.

Effect of film thickness on localized surface plasmon enhanced chemical sensor

NASA Astrophysics Data System (ADS)

Kassu, Aschalew; Farley, Carlton; Sharma, Anup; Kim, Wonkyu; Guo, Junpeng

2014-05-01

A highly-sensitive, reliable, simple and inexpensive chemical detection and identification platform is demonstrated. The sensing technique is based on localized surface plasmon enhanced Raman scattering measurements from gold-coated highly-ordered symmetric nanoporous ceramic membranes fabricated from anodic aluminum oxide. To investigate the effects of the thickness of the sputter-coated gold films on the sensitivity of sensor, and optimize the performance of the substrates, the geometry of the nanopores and the film thicknesses are varied in the range of 30 nm to 120 nm. To characterize the sensing technique and the detection limits, surface enhanced Raman scatterings of low concentrations of a standard chemical adsorbed on the gold coated substrates are collected and analyzed. The morphology of the proposed substrates is characterized by atomic force microscopy and the optical properties including transmittance, reflectance and absorbance of each substrate are also investigated.

Nanoporous Anodic Alumina: A Versatile Platform for Optical Biosensors

PubMed Central

Santos, Abel; Kumeria, Tushar; Losic, Dusan

2014-01-01

Nanoporous anodic alumina (NAA) has become one of the most promising nanomaterials in optical biosensing as a result of its unique physical and chemical properties. Many studies have demonstrated the outstanding capabilities of NAA for developing optical biosensors in combination with different optical techniques. These results reveal that NAA is a promising alternative to other widely explored nanoporous platforms, such as porous silicon. This review is aimed at reporting on the recent advances and current stage of development of NAA-based optical biosensing devices. The different optical detection techniques, principles and concepts are described in detail along with relevant examples of optical biosensing devices using NAA sensing platforms. Furthermore, we summarise the performance of these devices and provide a future perspective on this promising research field. PMID:28788678

Optical and structural characterisation of epitaxial nanoporous GaN grown by CVD.

PubMed

Mena, Josué; Carvajal, Joan J; Martínez, Oscar; Jiménez, Juan; Zubialevich, Vitaly Z; Parbrook, Peter J; Diaz, Francesc; Aguiló, Magdalena

2017-09-15

In this paper we study the optical properties of nanoporous gallium nitride (GaN) epitaxial layers grown by chemical vapour deposition on non-porous GaN substrates, using photoluminescence, cathodoluminescence, and resonant Raman scattering, and correlate them with the structural characteristic of these films. We pay special attention to the analysis of the residual strain of the layers and the influence of the porosity in the light extraction. The nanoporous GaN epitaxial layers are under tensile strain, although the strain is progressively reduced as the deposition time and the thickness of the porous layer increases, becoming nearly strain free for a thickness of 1.7 μm. The analysis of the experimental data point to the existence of vacancy complexes as the main source of the tensile strain.

Effect of Surface Pore Structure of Nerve Guide Conduit on Peripheral Nerve Regeneration

PubMed Central

Oh, Se Heang; Kim, Jin Rae; Kwon, Gu Birm; Namgung, Uk; Song, Kyu Sang

2013-01-01

Polycaprolactone (PCL)/Pluronic F127 nerve guide conduits (NGCs) with different surface pore structures (nano-porous inner surface vs. micro-porous inner surface) but similar physical and chemical properties were fabricated by rolling the opposite side of asymmetrically porous PCL/F127 membranes. The effect of the pore structure on peripheral nerve regeneration through the NGCs was investigated using a sciatic nerve defect model of rats. The nerve fibers and tissues were shown to have regenerated along the longitudinal direction through the NGC with a nano-porous inner surface (Nanopore NGC), while they grew toward the porous wall of the NGC with a micro-porous inner surface (Micropore NGC) and, thus, their growth was restricted when compared with the Nanopore NGC, as investigated by immunohistochemical evaluations (by fluorescence microscopy with anti-neurofilament staining and Hoechst staining for growth pattern of nerve fibers), histological evaluations (by light microscopy with Meyer's modified trichrome staining and Toluidine blue staining and transmission electron microscopy for the regeneration of axon and myelin sheath), and FluoroGold retrograde tracing (for reconnection between proximal and distal stumps). The effect of nerve growth factor (NGF) immobilized on the pore surfaces of the NGCs on nerve regeneration was not so significant when compared with NGCs not containing immobilized NGF. The NGC system with different surface pore structures but the same chemical/physical properties seems to be a good tool that is used for elucidating the surface pore effect of NGCs on nerve regeneration. PMID:22871377

Biomimetic Mineralization of Gold Nanoclusters as Multifunctional Thin Films for Glass Nanopore Modification, Characterization, and Sensing.

PubMed

Cao, Sumei; Ding, Shushu; Liu, Yingzi; Zhu, Anwei; Shi, Guoyue

2017-08-01

Hurdles of nanopore modification and characterization restrain the development of glass capillary-based nanopore sensing platforms. In this article, a simple but effective biomimetic mineralization method was developed to decorate glass nanopore with a thin film of bovine serum albumin-protected Au nanocluster (BSA-Au NC). The BSA-Au NC film emitted a strong red fluorescence whereby nondestructive characterization of Au film decorated at the inner surface of glass nanopore can be facilely achieved by a fluorescence microscopy. Besides, the BSA molecules played dual roles in the fabrication of functionalized Au thin film in glass nanopore: they not only directed the synthesis of fluorescent Au thin film but also provided binding sites for recognition, thus achieving synthesis-modification integration. This occurred due to the ionized carboxyl groups (-COO - ) of a BSA coating layer on Au NCs which can interacted with arginine (Arg) via guanidinium groups. The added Arg selectively led to the change in the charge and ionic current of BSA-Au NC film-decorated glass nanopore. Such ionic current responses can be used for quantifying Arg with a detection limit down to 1 fM, which was more sensitive than that of previous sensing systems. Together, the designed method exhibited great promise in providing a facile and controllable solution for glass nanopore modification, characterization, and sensing.

Synergistic effect of nanotopography and bioactive ions on peri-implant bone response

PubMed Central

Su, Yingmin; Komasa, Satoshi; Li, Peiqi; Nishizaki, Mariko; Chen, Luyuan; Terada, Chisato; Yoshimine, Shigeki; Nishizaki, Hiroshi; Okazaki, Joji

2017-01-01

Both bioactive ion chemistry and nanoscale surface modifications are beneficial for enhanced osseointegration of endosseous implants. In this study, a facile synthesis approach to the incorporation of bioactive Ca2+ ions into the interlayers of nanoporous structures (Ca-nano) formed on a Ti6Al4V alloy surface was developed by sequential chemical and heat treatments. Samples with a machined surface and an Na+ ion-incorporated nanoporous surface (Na-nano) fabricated by concentrated alkali and heat treatment were used in parallel for comparison. The bone response was investigated by microcomputed tomography assessment, sequential fluorescent labeling analysis, and histological and histomorphometric evaluation after 8 weeks of implantation in rat femurs. No significant differences were found in the nanotopography, surface roughness, or crystalline properties of the Ca-nano and Na-nano surfaces. Bone–implant contact was better in the Ca-nano and Na-nano implants than in the machined implant. The Ca-nano implant was superior to the Na-nano implant in terms of enhancing the volume of new bone formation. The bone formation activity consistently increased for the Ca-nano implant but ceased for the Na-nano implant in the late healing stage. These results suggest that Ca-nano implants have promising potential for application in dentistry and orthopedics. PMID:28184162

Enhanced Azo-Dyes Degradation Performance of Fe-Si-B-P Nanoporous Architecture

PubMed Central

Weng, Nan; Wang, Feng; Qin, Fengxiang; Tang, Wanying; Dan, Zhenhua

2017-01-01

Nanoporous structures were fabricated from Fe76Si9B10P5 amorphous alloy annealed at 773 K by dealloying in 0.05 M H2SO4 solution, as a result of preferential dissolution of α-Fe grains in form of the micro-coupling cells between α-Fe and cathodic residual phases. Nanoporous Fe-Si-B-P powders exhibit much better degradation performance to methyl orange and direct blue azo dyes compared with gas-atomized Fe76Si9B10P5 amorphous powders and commercial Fe powders. The degradation reaction rate constants of nanoporous powders are almost one order higher than those of the amorphous counterpart powders and Fe powders, accompanying with lower activation energies of 19.5 and 26.8 kJ mol−1 for the degradation reactions of methyl orange and direct blue azo dyes, respectively. The large surface area of the nanoporous structure, and the existence of metalloids as well as residual amorphous phase with high catalytic activity are responsible for the enhanced azo-dyes degradation performance of the nanoporous Fe-Si-B-P powders. PMID:28846622

Highly sensitive detection using microring resonator and nanopores

NASA Astrophysics Data System (ADS)

Bougot-Robin, K.; Hoste, J. W.; Le Thomas, N.; Bienstman, P.; Edel, J. B.

2016-04-01

One of the most significant challenges facing physical and biological scientists is the accurate detection and identification of single molecules in free-solution environments. The ability to perform such sensitive and selective measurements opens new avenues for a large number of applications in biological, medical and chemical analysis, where small sample volumes and low analyte concentrations are the norm. Access to information at the single or few molecules scale is rendered possible by a fine combination of recent advances in technologies. We propose a novel detection method that combines highly sensitive label-free resonant sensing obtained with high-Q microcavities and position control in nanoscale pores (nanopores). In addition to be label-free and highly sensitive, our technique is immobilization free and does not rely on surface biochemistry to bind probes on a chip. This is a significant advantage, both in term of biology uncertainties and fewer biological preparation steps. Through combination of high-Q photonic structures with translocation through nanopore at the end of a pipette, or through a solid-state membrane, we believe significant advances can be achieved in the field of biosensing. Silicon microrings are highly advantageous in term of sensitivity, multiplexing, and microfabrication and are chosen for this study. In term of nanopores, we both consider nanopore at the end of a nanopipette, with the pore being approach from the pipette with nanoprecise mechanical control. Alternatively, solid state nanopores can be fabricated through a membrane, supporting the ring. Both configuration are discussed in this paper, in term of implementation and sensitivity.

Nanoscale Dynamics of Joule heating and Bubble Nucleation in a Solid-State Nanopore

PubMed Central

Levine, Edlyn V.; Burns, Michael M.; Golovchenko, Jene A.

2016-01-01

We present a mathematical model for Joule heating of an electrolytic solution in a nanopore. The model couples the electrical and thermal dynamics responsible for rapid and extreme superheating of the electrolyte within the nanopore. The model is implemented numerically with a finite element calculation, yielding a time and spatially resolved temperature distribution in the nanopore region. Temperatures near the thermodynamic limit of superheat are predicted to be attained just before the explosive nucleation of a vapor bubble is observed experimentally. Knowledge of this temperature distribution enables the evaluation of related phenomena including bubble nucleation kinetics, relaxation oscillation, and bubble dynamics. PACS numbers 47.55.dp, 47.55.db, 85.35.-p, 05.70Fh PMID:26871171

Nanoporous cerium oxide thin film for glucose biosensor.

PubMed

Saha, Shibu; Arya, Sunil K; Singh, S P; Sreenivas, K; Malhotra, B D; Gupta, Vinay

2009-03-15

Nanoporous cerium oxide (CeO(2)) thin film deposited onto platinum (Pt) coated glass plate using pulsed laser deposition (PLD) has been utilized for immobilization of glucose oxidase (GOx). Atomic force microscopy studies reveal the formation of nanoporous surface morphology of CeO(2) thin film. Response studies carried out using differential pulsed voltammetry (DPV) and optical measurements show that the GOx/CeO(2)/Pt bio-electrode shows linearity in the range of 25-300 mg/dl of glucose concentration. The low value of Michaelis-Menten constant (1.01 mM) indicates enhanced enzyme affinity of GOx to glucose. The observed results show promising application of the nanoporous CeO(2) thin film for glucose sensing application without any surface functionalization or mediator.

Rational Design of Photonic Dust from Nanoporous Anodic Alumina Films: A Versatile Photonic Nanotool for Visual Sensing

PubMed Central

Chen, Yuting; Santos, Abel; Wang, Ye; Kumeria, Tushar; Ho, Daena; Li, Junsheng; Wang, Changhai; Losic, Dusan

2015-01-01

Herein, we present a systematic study on the development, optimisation and applicability of interferometrically coloured distributed Bragg reflectors based on nanoporous anodic alumina (NAA-DBRs) in the form of films and nanoporous microparticles as visual/colorimetric analytical tools. Firstly, we synthesise a complete palette of NAA-DBRs by galvanostatic pulse anodisation approach, in which the current density is altered in a periodic fashion in order to engineer the effective medium of the resulting photonic films in depth. NAA-DBR photonic films feature vivid colours that can be tuned across the UV-visible-NIR spectrum by structural engineering. Secondly, the effective medium of the resulting photonic films is assessed systematically by visual analysis and reflectometric interference spectroscopy (RIfS) in order to establish the most optimal nanoporous platforms to develop visual/colorimetric tools. Then, we demonstrate the applicability of NAA-DBR photonic films as a chemically selective sensing platform for visual detection of mercury(II) ions. Finally, we generate a new nanomaterial, so-called photonic dust, by breaking down NAA-DBRs films into nanoporous microparticles. The resulting microparticles (μP-NAA-DBRs) display vivid colours and are sensitive towards changes in their effective medium, opening new opportunities for developing advanced photonic nanotools for a broad range of applications. PMID:26245759

Rational Design of Photonic Dust from Nanoporous Anodic Alumina Films: A Versatile Photonic Nanotool for Visual Sensing

NASA Astrophysics Data System (ADS)

Chen, Yuting; Santos, Abel; Wang, Ye; Kumeria, Tushar; Ho, Daena; Li, Junsheng; Wang, Changhai; Losic, Dusan

2015-08-01

Herein, we present a systematic study on the development, optimisation and applicability of interferometrically coloured distributed Bragg reflectors based on nanoporous anodic alumina (NAA-DBRs) in the form of films and nanoporous microparticles as visual/colorimetric analytical tools. Firstly, we synthesise a complete palette of NAA-DBRs by galvanostatic pulse anodisation approach, in which the current density is altered in a periodic fashion in order to engineer the effective medium of the resulting photonic films in depth. NAA-DBR photonic films feature vivid colours that can be tuned across the UV-visible-NIR spectrum by structural engineering. Secondly, the effective medium of the resulting photonic films is assessed systematically by visual analysis and reflectometric interference spectroscopy (RIfS) in order to establish the most optimal nanoporous platforms to develop visual/colorimetric tools. Then, we demonstrate the applicability of NAA-DBR photonic films as a chemically selective sensing platform for visual detection of mercury(II) ions. Finally, we generate a new nanomaterial, so-called photonic dust, by breaking down NAA-DBRs films into nanoporous microparticles. The resulting microparticles (μP-NAA-DBRs) display vivid colours and are sensitive towards changes in their effective medium, opening new opportunities for developing advanced photonic nanotools for a broad range of applications.

AAO-CNTs electrode on microfluidic flow injection system for rapid iodide sensing.

PubMed

Phokharatkul, Ditsayut; Karuwan, Chanpen; Lomas, Tanom; Nacapricha, Duangjai; Wisitsoraat, Anurat; Tuantranont, Adisorn

2011-06-15

In this work, carbon nanotubes (CNTs) nanoarrays in anodized aluminum oxide (AAO-CNTs) nanopore is integrated on a microfluidic flow injection system for in-channel electrochemical detection of iodide. The device was fabricated from PDMS (polydimethylsiloxane) microchannel bonded on glass substrates that contains three-electrode electrochemical system, including AAO-CNTs as a working electrode, silver as a reference electrode and platinum as an auxiliary electrode. Aluminum, stainless steel catalyst, silver and platinum layers were sputtered on the glass substrate through shadow masks. Aluminum layer was then anodized by two-step anodization process to form nanopore template. CNTs were then grown in AAO template by thermal chemical vapor deposition. The amperometric detection of iodide was performed in 500-μm-wide and 100-μm-deep microchannels on the microfluidic chip. The influences of flow rate, injection volume and detection potential on the current response were optimized. From experimental results, AAO-CNTs electrode on chip offers higher sensitivity and wider dynamic range than CNTs electrode with no AAO template. Copyright © 2011 Elsevier B.V. All rights reserved.

In Situ Fabrication of PtCo Alloy Embedded in Nitrogen-Doped Graphene Nanopores as Synergistic Catalyst for Oxygen Reduction Reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhong, Xing; Wang, Lei; Zhou, Hu

A novel PtCo alloy in situ etched and embedded in graphene nanopores (PtCo/NPG) as a high-performance catalyst for ORR was reported. Graphene nanopores were fabricated in situ while forming PtCo nanoparticles that were uniformly embedded in the graphene nanopores. Given the synergistic effect between PtCo alloy and nanopores, PtCo/NPG exhibited 11.5 times higher mass activity than that of the commercial Pt/C cathode electrocatalyst. DFT calculations indicated that the nanopores in NPG cannot only stabilize PtCo nanoparticles but can also definitely change the electronic structures, thereby change its adsorption abilities. This enhancement can lead to a favorable reaction pathway on PtCo/NPGmore » for ORR. This study showed that PtCo/NPG is a potential candidate for the next generation of Pt-based catalysts in fuel cells. This study also offered a promising alternative strategy and enabled the fabrication of various kinds of metal/graphene nanopore nanohybrids with potential applications in catalysts and potential use for other technological devices. The authors acknowledge the financial support from the National Basic Research Program (973 program, No. 2013CB733501), Zhejiang Provincial Education Department Research Program (Y201326554) and the National Natural Science Foundation of China (No. 21306169, 21101137, 21136001, 21176221 and 91334013). D. Mei acknowledges the support from the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. Computing time was granted by the grand challenge of computational catalysis of the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL) and by the National Energy Research Scientific Computing Center (NERSC).« less

Hydroxyl-Exchanged Nanoporous Ionic Copolymer toward Low-Temperature Cycloaddition of Atmospheric Carbon Dioxide into Carbonates.

PubMed

Guo, Zengjing; Cai, Xiaochun; Xie, Jingyan; Wang, Xiaochen; Zhou, Yu; Wang, Jun

2016-05-25

An ionic copolymer catalyst with nanopores, large surface area, high ionic density, and superior basicity was prepared via the radical copolymerization of amino-functionalized ionic liquid bromide and divinylbenzene, followed with a hydroxyl exchange for removing bromonium. Evaluated in chemical fixation of CO2 with epoxides into cyclic carbonates in the absence of any solvent and basic additive, the nanoporous copolymer catalyst showed high and stable activity, superior to various control catalysts including the halogen-containing analogue. Further, high yields were obtained over a wide scope of substrates including aliphatic long carbon-chain alkyl epoxides and internal epoxide, even under atmospheric pressure and less than 100 °C for the majority of the substrates. On the basis of in situ Fourier transform infrared (FT-IR) investigation and density functional theory (DFT) calculation for the reaction intermediates, we proposed a possible reaction mechanism accounting for the superior catalytic activity of the ionic copolymer. The specifically prepared ionic copolymer material of this work features highly stable, noncorrosive, and sustainable catalysis and, thus, may be a new possibility for efficient chemical fixation of CO2 since it is an environmentally friendly, metal-free solid catalyst.

Fabrication of nanoporous thin-film working electrodes and their biosensing applications.

PubMed

Li, Tingjie; Jia, Falong; Fan, Yaxi; Ding, Zhifeng; Yang, Jun

2013-04-15

Electrochemical detection for point-of-care diagnostics is of great interest due to its high sensitivity, fast analysis time and ability to operate on a small scale. Herein, we report the fabrication of a nanoporous thin-film electrode and its application in the configuration of a simple and robust enzymatic biosensor. The nanoporous thin-film was formed in a planar gold electrode through an alloying/dealloying process. The nanoporous electrode has an electroactive surface area up to 40 times higher than that of a flat gold electrode of the same size. The nanoporous electrode was used as a substrate to build an enzymatic electrochemical biosensor for the detection of glucose in standard samples and control serum samples. The example glucose biosensor has a linear response up to 30 mM, with a high sensitivity of 0.50 μA mM⁻¹ mm⁻², and excellent anti-interference ability against lactate, uric acid and ascorbic acid. Abundant catalyst and enzyme were stably entrapped in the nanoporous structure, leading to high stability and reproducibility of the biosensor. Development of such nanoporous structure enables the miniaturization of high-performance electrochemical biosensors for point-of-care diagnostics or environmental field testing. Copyright © 2012 Elsevier B.V. All rights reserved.

Electroactive Nanoporous Metal Oxides and Chalcogenides by Chemical Design

PubMed Central

2017-01-01

The archetypal silica- and aluminosilicate-based zeolite-type materials are renowned for wide-ranging applications in heterogeneous catalysis, gas-separation and ion-exchange. Their compositional space can be expanded to include nanoporous metal chalcogenides, exemplified by germanium and tin sulfides and selenides. By comparison with the properties of bulk metal dichalcogenides and their 2D derivatives, these open-framework analogues may be viewed as three-dimensional semiconductors filled with nanometer voids. Applications exist in a range of molecule size and shape discriminating devices. However, what is the electronic structure of nanoporous metal chalcogenides? Herein, materials modeling is used to describe the properties of a homologous series of nanoporous metal chalcogenides denoted np-MX2, where M = Si, Ge, Sn, Pb, and X = O, S, Se, Te, with Sodalite, LTA and aluminum chromium phosphate-1 structure types. Depending on the choice of metal and anion their properties can be tuned from insulators to semiconductors to metals with additional modification achieved through doping, solid solutions, and inclusion (with fullerene, quantum dots, and hole transport materials). These systems form the basis of a new branch of semiconductor nanochemistry in three dimensions. PMID:28572706

Molecular Sensing by Nanoporous Crystalline Polymers

PubMed Central

Pilla, Pierluigi; Cusano, Andrea; Cutolo, Antonello; Giordano, Michele; Mensitieri, Giuseppe; Rizzo, Paola; Sanguigno, Luigi; Venditto, Vincenzo; Guerra, Gaetano

2009-01-01

Chemical sensors are generally based on the integration of suitable sensitive layers and transducing mechanisms. Although inorganic porous materials can be effective, there is significant interest in the use of polymeric materials because of their easy fabrication process, lower costs and mechanical flexibility. However, porous polymeric absorbents are generally amorphous and hence present poor molecular selectivity and undesired changes of mechanical properties as a consequence of large analyte uptake. In this contribution the structure, properties and some possible applications of sensing polymeric films based on nanoporous crystalline phases, which exhibit all identical nanopores, will be reviewed. The main advantages of crystalline nanoporous polymeric materials with respect to their amorphous counterparts are, besides a higher selectivity, the ability to maintain their physical state as well as geometry, even after large guest uptake (up to 10–15 wt%), and the possibility to control guest diffusivity by controlling the orientation of the host polymeric crystalline phase. The final section of the review also describes the ability of suitable polymeric films to act as chirality sensors, i.e., to sense and memorize the presence of non-racemic volatile organic compounds. PMID:22303150

Electrical characteristics in reverse electrodialysis using nanoporous membranes

NASA Astrophysics Data System (ADS)

Chanda, Sourayon; Tsai, Peichun Amy

2017-11-01

We experimentally and numerically investigate the effects of concentration difference and flow velocity on sustainable electricity generation and associated fluid dynamics using a single reverse electrodialysis (RED) cell. By exploiting the charge-selective nature of nanoporous interfaces, electrical energy is generated by reverse electrodialysis harnessing chemical Gibbs energy via a salinity gradient. Experimentally, a RED cell was designed with two reservoirs, which are separated by a nanoporous, cation-selective membrane. We injected deionized water through one reservoir, whereas a solution of high salt concentration through the other. The gradient of salt concentration primarily drives the flow in the charged nano-pores, due to the interplay between charge selectivity, diffusion processes, and electro-migration. The current-voltage characteristics of the single RED cell shows a linear current-voltage relationship, similar to an electrochemical cell. The membrane resistance is increased with increasing salt concentration difference and external flow rate. The present experimental work was further analyzed numerically to better understand the detailed electrical and flow fields under different concentration gradients and external flows. NSERC Discovery, Accelerator, and CRC Programs.

Resolved single-molecule detection of individual species within a mixture of anti-biotin antibodies using an engineered monomeric nanopore.

PubMed

Fahie, Monifa; Chisholm, Christina; Chen, Min

2015-02-24

Oligomeric protein nanopores with rigid structures have been engineered for the purpose of sensing a wide range of analytes including small molecules and biological species such as proteins and DNA. We chose a monomeric β-barrel porin, OmpG, as the platform from which to derive the nanopore sensor. OmpG is decorated with seven flexible loops that move dynamically to create a distinct gating pattern when ionic current passes through the pore. Biotin was chemically tethered to the most flexible one of these loops. The gating characteristic of the loop's movement in and out of the porin was substantially altered by analyte protein binding. The gating characteristics of the pore with bound targets were remarkably sensitive to molecular identity, even providing the ability to distinguish between homologues within an antibody mixture. A total of five gating parameters were analyzed for each analyte to create a unique fingerprint for each biotin-binding protein. Our exploitation of gating noise as a molecular identifier may allow more sophisticated sensor design, while OmpG's monomeric structure greatly simplifies nanopore production.

Nanoporous polymeric nanofibers based on selectively etched PS-b-PDMS block copolymers.

PubMed

Demirel, Gokcen B; Buyukserin, Fatih; Morris, Michael A; Demirel, Gokhan

2012-01-01

One-dimensional nanoporous polymeric nanofibers have been fabricated within an anodic aluminum oxide (AAO) membrane by a facile approach based on selective etching of poly(dimethylsiloxane) (PDMS) domains in polystyrene-block-poly(dimethylsiloxane) (PS-b-PDMS) block copolymers that had been formed within the AAO template. It was observed that prior to etching, the well-ordered PS-b-PDMS nanofibers are solid and do not have any porosity. The postetched PS nanofibers, on the other hand, had a highly porous structure having about 20-50 nm pore size. The nanoporous polymeric fibers were also employed as a drug carrier for the native, continuous, and pulsatile drug release using Rhodamine B (RB) as a model drug. These studies showed that enhanced drug release and tunable drug dosage can be achieved by using ultrasound irradiation. © 2011 American Chemical Society

Immobilization of Enzymes in Nanoporous Host Materials: A Nanobiotechnological Approach to Decontamination and Demilitarization of Chemical and Biological Warfare Agents

DTIC Science & Technology

2002-05-06

Organophosphorus compounds (OPs) are highly toxic and found extensive use as pesticides , insecticides and potential chemical warfare (CW) agents . Recently...commonly used substrate, the serine protease inhibitor diisopropyl fluorophosphates (DFP), and different fluoride-containing G-type nerve agents such as...

Development of a DNA Sensor Based on Nanoporous Pt-Rich Electrodes

NASA Astrophysics Data System (ADS)

Van Hao, Pham; Thanh, Pham Duc; Xuan, Chu Thi; Hai, Nguyen Hoang; Tuan, Mai Anh

2017-06-01

Nanoporous Pt-rich electrodes with 72 at.% Pt composition were fabricated by sputtering a Pt-Ag alloy, followed by an electrochemical dealloying process to selectively etch away Ag atoms. The surface properties of nanoporous membranes were investigated by energy-dispersive x-ray spectroscopy (EDS), scanning electron microscopy (SEM), atomic force microscopy (AFM), a documentation system, and a gel image system (Gel Doc Imager). A single strand of probe deoxyribonucleic acid (DNA) was immobilized onto the electrode surface by physical adsorption. The DNA probe and target hybridization were measured using a lock-in amplifier and an electrochemical impedance spectroscope (EIS). The nanoporous Pt-rich electrode-based DNA sensor offers a fast response time of 3.7 s, with a limit of detection (LOD) of 4.35 × 10-10 M of DNA target.

Conformational Transitions and Stop-and-Go Nanopore Transport of Single Stranded DNA on Charged Graphene

PubMed Central

Shankla, Manish; Aksimentiev, Aleksei

2014-01-01

Control over interactions with biomolecules holds the key to applications of graphene in biotechnology. One such application is nanopore sequencing, where a DNA molecule is electrophoretically driven through a graphene nanopore. Here, we investigate how interactions of single-stranded DNA and a graphene membrane can be controlled by electrically biasing the membrane. The results of our molecular dynamics simulations suggest that electric charge on graphene can force a DNA homopolymer to adopt a range of strikingly different conformations. The conformational response is sensitive to even very subtle nucleotide modifications, such as DNA methylation. The speed of DNA motion through a graphene nanopore is strongly affected by the graphene charge: a positive charge accelerates the motion whereas a negative charge arrests it. As a possible application of the effect, we demonstrate stop-and-go transport of DNA controlled by the charge of graphene. Such on-demand transport of DNA is essential for realizing nanopore sequencing. PMID:25296960

A Hybrid Semi-Digital Transimpedance Amplifier With Noise Cancellation Technique for Nanopore-Based DNA Sequencing.

PubMed

Hsu, Chung-Lun; Jiang, Haowei; Venkatesh, A G; Hall, Drew A

2015-10-01

Over the past two decades, nanopores have been a promising technology for next generation deoxyribonucleic acid (DNA) sequencing. Here, we present a hybrid semi-digital transimpedance amplifier (HSD-TIA) to sense the minute current signatures introduced by single-stranded DNA (ssDNA) translocating through a nanopore, while discharging the baseline current using a semi-digital feedback loop. The amplifier achieves fast settling by adaptively tuning a DC compensation current when a step input is detected. A noise cancellation technique reduces the total input-referred current noise caused by the parasitic input capacitance. Measurement results show the performance of the amplifier with 31.6 M Ω mid-band gain, 950 kHz bandwidth, and 8.5 fA/ √Hz input-referred current noise, a 2× noise reduction due to the noise cancellation technique. The settling response is demonstrated by observing the insertion of a protein nanopore in a lipid bilayer. Using the nanopore, the HSD-TIA was able to measure ssDNA translocation events.

Conformational transitions and stop-and-go nanopore transport of single-stranded DNA on charged graphene

NASA Astrophysics Data System (ADS)

Shankla, Manish; Aksimentiev, Aleksei

2014-10-01

Control over interactions with biomolecules holds the key to applications of graphene in biotechnology. One such application is nanopore sequencing, where a DNA molecule is electrophoretically driven through a graphene nanopore. Here we investigate how interactions of single-stranded DNA and a graphene membrane can be controlled by electrically biasing the membrane. The results of our molecular dynamics simulations suggest that electric charge on graphene can force a DNA homopolymer to adopt a range of strikingly different conformations. The conformational response is sensitive to even very subtle nucleotide modifications, such as DNA methylation. The speed of DNA motion through a graphene nanopore is strongly affected by the graphene charge: a positive charge accelerates the motion, whereas a negative charge arrests it. As a possible application of the effect, we demonstrate stop-and-go transport of DNA controlled by the charge of graphene. Such on-demand transport of DNA is essential for realizing nanopore sequencing.

Responsive nanoporous metals: recoverable modulations on strength and shape by watering

NASA Astrophysics Data System (ADS)

Ye, Xing-Long; Liu, Ling-Zhi; Jin, Hai-Jun

2016-08-01

Many biological materials can readily modulate their mechanical properties and shape by interacting with water in the surrounding environment, which is essential to their high performance in application. In contrast, typical inorganic materials (such as the metals) cannot change their strength and shape without involving thermal/mechanical treatments. By introducing nano-scale porous structure and exploiting a simple physical concept—the water-capillarity in nanopores, here we report that a ‘dead’ metal can be transformed into a ‘smart’ material with water-responsive properties. We demonstrate that the apparent strength, volume and shape of nanoporous Au and Au(Pt) can be modulated in situ, dramatically and recoverably, in response to water-dipping and partial-drying. The amplitude of strength-modulation reaches 20 MPa, which is nearly 50% of the yield strength at initial state. This approach also leads to reversible length change up to 1.3% in nanoporous Au and a large reversible bending motion of a bi-layer strip with tip displacement of ˜20 mm, which may be used for actuation. This method is simple and effective, occurring in situ under ambient conditions and requiring no external power, analogous to biological materials. The findings may open up novel applications in many areas such as micro-robotics and bio-medical devices.

Preparation, Modification, Characterization, and Biosensing Application of Nanoporous Gold Using Electrochemical Techniques

PubMed Central

Neupane, Dharmendra; Nepal, Bishal; Mikhaylov, Vasilii; Stine, Keith J.

2018-01-01

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. PMID:29547580

Preparation, Modification, Characterization, and Biosensing Application of Nanoporous Gold Using Electrochemical Techniques.

PubMed

Bhattarai, Jay K; Neupane, Dharmendra; Nepal, Bishal; Mikhaylov, Vasilii; Demchenko, Alexei V; Stine, Keith J

2018-03-16

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.

Methods And Devices For Characterizing Duplex Nucleic Acid Molecules

DOEpatents

Akeson, Mark; Vercoutere, Wenonah; Haussler, David; Winters-Hilt, Stephen

2005-08-30

Methods and devices are provided for characterizing a duplex nucleic acid, e.g., a duplex DNA molecule. In the subject methods, a fluid conducting medium that includes a duplex nucleic acid molecule is contacted with a nanopore under the influence of an applied electric field and the resulting changes in current through the nanopore caused by the duplex nucleic acid molecule are monitored. The observed changes in current through the nanopore are then employed as a set of data values to characterize the duplex nucleic acid, where the set of data values may be employed in raw form or manipulated, e.g., into a current blockade profile. Also provided are nanopore devices for practicing the subject methods, where the subject nanopore devices are characterized by the presence of an algorithm which directs a processing means to employ monitored changes in current through a nanopore to characterize a duplex nucleic acid molecule responsible for the current changes. The subject methods and devices find use in a variety of applications, including, among other applications, the identification of an analyte duplex DNA molecule in a sample, the specific base sequence at a single nulceotide polymorphism (SNP), and the sequencing of duplex DNA molecules.

Surface effects on the radiation response of nanoporous Au foams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, E. G.; Caro, M.; Wang, Y. Q.

2012-11-05

We report on an experimental and simulation campaign aimed at exploring the radiation response of nanoporous Au (np-Au) foams. We find different defect accumulation behavior by varying radiation dose-rate in ion-irradiated np-Au foams. Stacking fault tetrahedra are formed when np-Au foams are irradiated at high dose-rate, but they do not seem to be formed in np-Au at low dose-rate irradiation. A model is proposed to explain the dose-rate dependent defect accumulation based on these results.

Observation and analysis of the Coulter effect through carbon nanotube and graphene nanopores.

PubMed

Agrawal, Kumar Varoon; Drahushuk, Lee W; Strano, Michael S

2016-02-13

Carbon nanotubes (CNTs) and graphene are the rolled and flat analogues of graphitic carbon, respectively, with hexagonal crystalline lattices, and show exceptional molecular transport properties. The empirical study of a single isolated nanopore requires, as evidence, the observation of stochastic, telegraphic noise from a blocking molecule commensurate in size with the pore. This standard is used ubiquitously in patch clamp studies of single, isolated biological ion channels and a wide range of inorganic, synthetic nanopores. In this work, we show that observation and study of stochastic fluctuations for carbon nanopores, both CNTs and graphene-based, enable precision characterization of pore properties that is otherwise unattainable. In the case of voltage clamp measurements of long (0.5-1 mm) CNTs between 0.9 and 2.2 nm in diameter, Coulter blocking of cationic species reveals the complex structuring of the fluid phase for confined water in this diameter range. In the case of graphene, we have pioneered the study and the analysis of stochastic fluctuations in gas transport from a pressurized, graphene-covered micro-well compartment that reveal switching between different values of the membrane permeance attributed to chemical rearrangements of individual graphene pores. This analysis remains the only way to study such single isolated graphene nanopores under these realistic transport conditions of pore rearrangements, in keeping with the thesis of this work. In summary, observation and analysis of Coulter blocking or stochastic fluctuations of permeating flux is an invaluable tool to understand graphene and graphitic nanopores including CNTs. © 2015 The Author(s).

Fabrication and Characterization of Nanoporous Niobia, and Nanotubular Tantala, Titania and Zirconia via Anodization

PubMed Central

Minagar, Sepideh; Berndt, Christopher C.; Wen, Cuie

2015-01-01

Valve metals such as titanium (Ti), zirconium (Zr), niobium (Nb) and tantalum (Ta) that confer a stable oxide layer on their surfaces are commonly used as implant materials or alloying elements for titanium-based implants, due to their exceptional high corrosion resistance and excellent biocompatibility. The aim of this study was to investigate the bioactivity of the nanostructures of tantala (Ta2O5), niobia (Nb2O5), zirconia (ZrO2) and titania (TiO2) in accordance to their roughness and wettability. Therefore, four kinds of metal oxide nanoporous and nanotubular Ta2O5, Nb2O5, ZrO2 and TiO2 were fabricated via anodization. The nanosize distribution, morphology and the physical and chemical properties of the nanolayers and their surface energies and bioactivities were investigated using SEM-EDS, X-ray diffraction (XRD) analysis and 3D profilometer. It was found that the nanoporous Ta2O5 exhibited an irregular porous structure, high roughness and high surface energy as compared to bare tantalum metal; and exhibited the most superior bioactivity after annealing among the four kinds of nanoporous structures. The nanoporous Nb2O5 showed a uniform porous structure and low roughness, but no bioactivity before annealing. Overall, the nanoporous and nanotubular layers of Ta2O5, Nb2O5, ZrO2 and TiO2 demonstrated promising potential for enhanced bioactivity to improve their biomedical application alone or to improve the usage in other biocompatible metal implants. PMID:25837724

Electrochemical Generation of a Hydrogen Bubble at a Recessed Platinum Nanopore Electrode.

PubMed

Chen, Qianjin; Luo, Long; White, Henry S

2015-04-21

We report the electrochemical generation of a single hydrogen bubble within the cavity of a recessed Pt nanopore electrode. The recessed Pt electrode is a conical pore in glass that contains a micrometer-scale Pt disk (1-10 μm radius) at the nanopore base and a nanometer-scale orifice (10-100 nm radius) that restricts diffusion of electroactive molecules and dissolved gas between the nanopore cavity and bulk solution. The formation of a H2 bubble at the Pt disk electrode in voltammetric experiments results from the reduction of H(+) in a 0.25 M H2SO4 solution; the liquid-to-gas phase transformation is indicated in the voltammetric response by a precipitous decrease in the cathodic current due to rapid bubble nucleation and growth within the nanopore cavity. Finite element simulations of the concentration distribution of dissolved H2 within the nanopore cavity, as a function of the H(+) reduction current, indicate that H2 bubble nucleation at the recessed Pt electrode surface occurs at a critical supersaturation concentration of ∼0.22 M, in agreement with the value previously obtained at (nonrecessed) Pt disk electrodes (∼0.25 M). Because the nanopore orifice limits the diffusion of H2 out of the nanopore cavity, an anodic peak corresponding to the oxidation of gaseous and dissolved H2 trapped in the recessed cavity is readily observed on the reverse voltammetric scan. Integration of the charge associated with the H2 oxidation peak is found to approach that of the H(+) reduction peak at high scan rates, confirming the assignment of the anodic peak to H2 oxidation. Preliminary results for the electrochemical generation of O2 bubbles from water oxidation at a recessed nanopore electrode are consistent with the electrogeneration of H2 bubbles.

High quality self-separated GaN crystal grown on a novel nanoporous template by HVPE.

PubMed

Huo, Qin; Shao, Yongliang; Wu, Yongzhong; Zhang, Baoguo; Hu, Haixiao; Hao, Xiaopeng

2018-02-16

In this study, a novel nanoporous template was obtained by a two-step etching process from MOCVD-GaN/Al 2 O 3 (MGA) with electrochemical etching sequentially followed by chemical wet etching. The twice-etched MOCVD-GaN/Al 2 O 3 (TEMGA) templates were utilized to grow GaN crystals by hydride vapor phase epitaxy (HVPE) method. The GaN crystals were separated spontaneously from the TEMGA template with the assistance of voids formed by the etched nanopores. Several techniques were utilized to characterize the quality of the free-standing GaN crystals obtained from the TEMGA template. Results showed that the quality of the as-obtained GaN crystals was improved obviously compared with those grown on the MGA. This convenient technique can be applied to grow high-quality free-standing GaN crystals.

Planarized arrays of aligned, untangled multiwall carbon nanotubes with Ohmic back contacts

DOE PAGES

Rochford, C.; Limmer, S. J.; Howell, S. W.; ...

2014-11-26

Vertically aligned, untangled planarized arrays of multiwall carbon nanotubes (MWNTs) with Ohmic back contacts were grown in nanopore templates on arbitrary substrates. The templates were prepared by sputter depositing Nd-doped Al films onto W-coated substrates, followed by anodization to form an aluminum oxide nanopore array. The W underlayer helps eliminate the aluminum oxide barrier that typically occurs at the nanopore bottoms by instead forming a thin WO 3 layer. The WO 3 can be selectively etched to enable electrodeposition of Co catalysts with control over the Co site density. This led to control of the site density of MWNTs grownmore » by thermal chemical vapor deposition, with the W also serving as a back electrical contact. As a result, Ohmic contact to MWNTs was confirmed, even following ultrasonic cutting of the entire array to a uniform height.« less

Bottom-up synthesis of multifunctional nanoporous graphene

NASA Astrophysics Data System (ADS)

Moreno, César; Vilas-Varela, Manuel; Kretz, Bernhard; Garcia-Lekue, Aran; Costache, Marius V.; Paradinas, Markos; Panighel, Mirko; Ceballos, Gustavo; Valenzuela, Sergio O.; Peña, Diego; Mugarza, Aitor

2018-04-01

Nanosize pores can turn semimetallic graphene into a semiconductor and, from being impermeable, into the most efficient molecular-sieve membrane. However, scaling the pores down to the nanometer, while fulfilling the tight structural constraints imposed by applications, represents an enormous challenge for present top-down strategies. Here we report a bottom-up method to synthesize nanoporous graphene comprising an ordered array of pores separated by ribbons, which can be tuned down to the 1-nanometer range. The size, density, morphology, and chemical composition of the pores are defined with atomic precision by the design of the molecular precursors. Our electronic characterization further reveals a highly anisotropic electronic structure, where orthogonal one-dimensional electronic bands with an energy gap of ∼1 electron volt coexist with confined pore states, making the nanoporous graphene a highly versatile semiconductor for simultaneous sieving and electrical sensing of molecular species.

Nano/macro porous bioactive glass scaffold

NASA Astrophysics Data System (ADS)

Wang, Shaojie

Bioactive glass (BG) and ceramics have been widely studied and developed as implants to replace hard tissues of the musculo-skeletal system, such as bones and teeth. Recently, instead of using bulk materials, which usually do not degrade rapidly enough and may remain in the human body for a long time, the idea of bioscaffold for tissue regeneration has generated much interest. An ideal bioscaffold is a porous material that would not only provide a three-dimensional structure for the regeneration of natural tissue, but also degrade gradually and, eventually be replaced by the natural tissue completely. Among various material choices the nano-macro dual porous BG appears as the most promising candidate for bioscaffold applications. Here macropores facilitate tissue growth while nanopores control degradation and enhance cell response. The surface area, which controls the degradation of scaffold can also be tuned by changing the nanopore size. However, fabrication of such 3D structure with desirable nano and macro pores has remained challenging. In this dissertation, sol-gel process combined with spinodal decomposition or polymer sponge replication method has been developed to fabricate the nano-macro porous BG scaffolds. Macropores up to 100microm are created by freezing polymer induced spinodal structure through sol-gel transition, while larger macropores (>200um) of predetermined size are obtained by the polymer sponge replication technique. The size of nanopores, which are inherent to the sol-gel method of glass fabrication, has been tailored using several approaches: Before gel point, small nanopores are generated using acid catalyst that leads to weakly-branched polymer-like network. On the other hand, larger nanopores are created with the base-catalyzed gel with highly-branched cluster-like structure. After the gel point, the nanostructure can be further modified by manipulating the sintering temperature and/or the ammonia concentration used in the solvent exchange process. Although both techniques lower the surface area of BG scaffolds, the temperature-dependent sintering process closes nanopores through densification, while the concentration-dependent solvent exchange process enlarges nanopores through Ostwald-ripening type coarsening. Therefore, nanopore size and surface area of BG scaffold are independently controlled using these methods. In vitro cell and in vivo animal tissue responses have been investigated to evaluate the performance of the nano-macro porous BG scaffold. The cells are found to migrate and penetrate deep into the 3D nano-macro porous structure, while exhibiting excellent adhesion to the bioscaffold surface. Importantly, the new tissue with both blood vessels and collagen fibers is formed deep inside the implanted scaffolds without obvious inflammatory reaction. Furthermore, our observations show biological benefits of the nanopores in the BG scaffold. In comparison to BG scaffold without nanopores, cells migrate and penetrate into nano-macro dual-porous BG scaffold faster and deeper mainly because of the increase of surface area. To study the effect of nanopore topography, we fabricated BG scaffolds with the same surface area but different nanopore sizes. It is found that the initial cell attachment is significantly enhanced on the BG scaffold with the same surface area but smaller nanopores size, indicating that the nanopore topography strongly influences the performance of BG scaffold. In conclusion, the present results demonstrate most clearly the usefulness of our nano-macro dual-porous BG as a novel and superior 3D bioscaffold for regenerative medicine and hard tissue engineering.

Ion Current Rectification, Limiting and Overlimiting Conductances in Nanopores

PubMed Central

van Oeffelen, Liesbeth; Van Roy, Willem; Idrissi, Hosni; Charlier, Daniel; Lagae, Liesbet; Borghs, Gustaaf

2015-01-01

Previous reports on Poisson-Nernst-Planck (PNP) simulations of solid-state nanopores have focused on steady state behaviour under simplified boundary conditions. These are Neumann boundary conditions for the voltage at the pore walls, and in some cases also Donnan equilibrium boundary conditions for concentrations and voltages at both entrances of the nanopore. In this paper, we report time-dependent and steady state PNP simulations under less restrictive boundary conditions, including Neumann boundary conditions applied throughout the membrane relatively far away from the nanopore. We simulated ion currents through cylindrical and conical nanopores with several surface charge configurations, studying the spatial and temporal dependence of the currents contributed by each ion species. This revealed that, due to slow co-diffusion of oppositely charged ions, steady state is generally not reached in simulations or in practice. Furthermore, it is shown that ion concentration polarization is responsible for the observed limiting conductances and ion current rectification in nanopores with asymmetric surface charges or shapes. Hence, after more than a decade of collective research attempting to understand the nature of ion current rectification in solid-state nanopores, a relatively intuitive model is retrieved. Moreover, we measured and simulated current-voltage characteristics of rectifying silicon nitride nanopores presenting overlimiting conductances. The similarity between measurement and simulation shows that overlimiting conductances can result from the increased conductance of the electric double-layer at the membrane surface at the depletion side due to voltage-induced polarization charges. The MATLAB source code of the simulation software is available via the website http://micr.vub.ac.be. PMID:25978328

Photoelectrochemical response and corrosion behavior of CdS/TiO2 nanocomposite films in an aerated 0.5 M NaCl solution

NASA Astrophysics Data System (ADS)

Boonserm, Aleena; Kruehong, Chaiyaput; Seithtanabutara, Varinrumpai; Artnaseaw, Apichart; Kwakhong, Panomkorn

2017-10-01

This research aimed to investigate the photoelectrochemical response and corrosion behavior of CdS/TiO2 nanocomposite films using electrochemical measurements in an aerated 0.5 M NaCl solution under white light illumination. The CdS/TiO2 nanocomposite films were prepared by chemical bath deposition technique in a solution of cadmium and sulfide ions. The high resolution images of CdS/TiO2 nanocomposite films were provided by field emission scanning electron microscope. Theirs chemical identification and quantitative compositional information, crystallinity and actual chemical compounds formed were determined by energy dispersive spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy, respectively. The results indicated that the photoelectrochemical activity of the films depended strongly on CdS content. From the preparation of CdS/TiO2 nanocomposite films by 5, 10 and 15 dipping cycles in the chemical solutions, the best photoelectrochemical response was revealed by the 10 dipping cycles-prepared film. Galvanic couple testing demonstrated that the photoelectrochemical response of the film decreased continuously compared to that of anodized nanoporous TiO2 substrate which described by photocorrosion of CdS nanoparticles. In addition, chloride-ion attack also induced pitting corrosion leading to fluctuation and deterioration of photoelectrochemical response. CdO2 and Cd(OH)2 depositions were found as the main photocorrosion products on collapsed nanostructured-surface. The relevance between photoelectrochemical response and corrosion behavior of CdS/TiO2 nanocomposite film was discussed in detail.

Fabrication and characterization of conductive anodic aluminum oxide substrates

NASA Astrophysics Data System (ADS)

Altuntas, Sevde; Buyukserin, Fatih

2014-11-01

Biomaterials that allow the utilization of electrical, chemical and topographic cues for improved neuron-material interaction and neural regeneration hold great promise for nerve tissue engineering applications. The nature of anodic aluminum oxide (AAO) membranes intrinsically provides delicate control over topographic and chemical cues for enhanced cell interaction; however their use in nerve regeneration is still very limited. Herein, we report the fabrication and characterization of conductive AAO (CAAO) surfaces for the ultimate goal of integrating electrical cues for improved nerve tissue behavior on the nanoporous substrate material. Parafilm was used as a protecting polymer film, for the first time, in order to obtain large area (50 cm2) free-standing AAO membranes. Carbon (C) was then deposited on the AAO surface via sputtering. Morphological characterization of the CAAO surfaces revealed that the pores remain open after the deposition process. The presence of C on the material surface and inside the nanopores was confirmed by XPS and EDX studies. Furthermore, I-V curves of the surface were used to extract surface resistance values and conductive AFM demonstrated that current signals can only be achieved where conductive C layer is present. Finally, novel nanoporous C films with controllable pore diameters and one dimensional (1-D) C nanostructures were obtained by the dissolution of the template AAO substrate.

Synthesis of nanoporous CuO/TiO2/Pd-NiO composite catalysts by chemical dealloying and their performance for methanol and ethanol electro-oxidation

NASA Astrophysics Data System (ADS)

Niu, Mengying; Xu, Wence; Zhu, Shengli; Liang, Yanqin; Cui, Zhenduo; Yang, Xianjin; Inoue, Akihisa

2017-09-01

Nanoporous CuO/TiO2/Pd-NiO-x (x = 0, 1, 3, 5, 7 at%) catalysts have been synthesized by dealloying Cu-Ti-Pd-Ni alloy ribbons in acid solution. The nanoporous structure and chemical composition of the catalysts distribute uniformly. Based on the electrochemical active area (EASA), electrocatalytic activity and stability, the np-CuO/TiO2/Pd-NiO-3 catalyst possesses the best performance for methanol and ethanol electro-oxidation. For methanol and ethanol electro-oxidation, the anodic current densities in forward scan of the np-CuO/TiO2/Pd-NiO-3 catalyst are about 5.6 times and 2.1 times larger than that of the np-CuO/TiO2/Pd catalyst, respectively. The introduction of NiO provides more electrochemical active sites due to the improved geometrical and bifunctional mechanism. NiO promotes the adsorption of oxygen-containing species (OHads) on the catalyst surface, and electron effect between Pd and Ni is favorable for charge transfer. This accelerates the removal of intermediate products during the oxidation process. The electrocatalytic processes of methanol and ethanol oxidation in alkaline solution are controlled by both charge transfer and diffusion.

Tailoring Pore Size and Chemical Interior of near 1 nm Sized Pores in a Nanoporous Polymer Based on a Discotic Liquid Crystal

PubMed Central

2017-01-01

A triazine based disc shaped molecule with two hydrolyzable units, imine and ester groups, was polymerized via acyclic diene metathesis in the columnar hexagonal (Colhex) LC phase. Fabrication of a cationic nanoporous polymer (pore diameter ∼1.3 nm) lined with ammonium groups at the pore surface was achieved by hydrolysis of the imine linkage. Size selective aldehyde uptake by the cationic porous polymer was demonstrated. The anilinium groups in the pores were converted to azide as well as phenyl groups by further chemical treatment, leading to porous polymers with neutral functional groups in the pores. The pores were enlarged by further hydrolysis of the ester groups to create ∼2.6 nm pores lined with −COONa surface groups. The same pores could be obtained in a single step without first hydrolyzing the imine linkage. XRD studies demonstrated that the Colhex order of the monomer was preserved after polymerization as well as in both the nanoporous polymers. The porous anionic polymer lined with −COOH groups was further converted to the −COOLi, −COONa, −COOK, −COOCs, and −COONH4 salts. The porous polymer lined with −COONa groups selectively adsorbs a cationic dye, methylene blue, over an anionic dye. PMID:28416888

Enzyme-modified nanoporous gold-based electrochemical biosensors.

PubMed

Qiu, Huajun; Xue, Luyan; Ji, Guanglei; Zhou, Guiping; Huang, Xirong; Qu, Yinbo; Gao, Peiji

2009-06-15

On the basis of the unique physical and chemical properties of nanoporous gold (NPG), which was obtained simply by dealloying Ag from Au/Ag alloy, an attempt was made in the present study to develop NPG-based electrochemical biosensors. The NPG-modified glassy carbon electrode (NPG/GCE) exhibited high-electrocatalytic activity toward the oxidation of nicotinamide adenine dinucleotide (NADH) and hydrogen peroxide (H(2)O(2)), which resulted in a remarkable decrease in the overpotential of NADH and H(2)O(2) electro-oxidation when compared with the gold sheet electrode. The high density of edge-plane-like defective sites and large specific surface area of NPG should be responsible for the electrocatalytic behavior. Such electrocatalytic behavior of the NPG/GCE permitted effective low-potential amperometric biosensing of ethanol or glucose via the incorporation of alcohol dehydrogenase (ADH) or glucose oxidase (GOD) within the three-dimensional matrix of NPG. The ADH- and GOD-modified NPG-based biosensors showed good analytical performance for biosensing ethanol and glucose due to the clean, reproducible and uniformly distributed microstructure of NPG. The stabilization effect of NPG on the incorporated enzymes also made the constructed biosensors very stable. After 1 month storage at 4 degrees C, the ADH- and GOD-based biosensors lost only 5.0% and 4.2% of the original current response. All these indicated that NPG was a promising electrode material for biosensors construction.

Fabrication of a high-density nano-porous structure on polyimide by using ultraviolet laser irradiation

NASA Astrophysics Data System (ADS)

Ma, Yong-Won; Jeong, Myung Yung; Lee, Sang-Mae; Shin, Bo Sung

2016-03-01

A new approach for fabricating a high-density nano-porous structure on polyimide (PI) by using a 355-nm UV laser is presented here. When PI was irradiated by using a laser, debris that had electrical conductivity was generated. Accordingly, that debris caused electrical defects in the field of electronics. Thus, many researchers have tried to focus on a clean processing without debris. However, this study focused on forming a high density of debris so as to fabricate a nano-porous structure consisting of nanofibers on the PI film. A PI film with closed pores and open pores was successfully formed by using a chemical blowing agent (azodicarbonamide, CBA) in an oven. Samples were precured at 130 °C and cured at 205 °C in sequence so that the closed pores might not coalesce in the film. When the laser irradiated the PI film with closed pores, nanofibers were generated because polyimide was not completely decomposed by photochemical ablation. Our results indicated that a film with micro-closed pores, in conjunction with a 355-nm pulsed laser, can facilitate the fabrication of a high-density nano-porous structure.

Wettability transition induced transformation and entrapment of polymer nanostructures in cylindrical nanopores.

PubMed

Feng, Xunda; Mei, Shilin; Jin, Zhaoxia

2011-12-06

We apply the concept of wettability transition to manipulate the morphology and entrapment of polymer nanostructures inside cylindrical nanopores of anodic aluminum oxide (AAO) membranes. When AAO/polystyrene (PS) hybrids, i.e., AAO/PS nanorods or AAO/PS nanotubes, are immersed into a polyethylene glycol (PEG) reservoir above the glass transition temperature of PS, a wettability transition from wetting to nonwetting of PS can be triggered due to the invasion of the more wettable PEG melt. The wettability transition enables us to develop a nondestructive method to entrap hemispherically capped nanorods inside nanopores. Moreover, we can obtain single nanorods with the desired aspect ratio by further dissolving the AAO template, in contrast to the drawbacks of nonuniformity or destructiveness from the conventional ultrasonication method. In the case of AAO/PS nanotubes, the wettability transition induced dewetting of PS nanotube walls results in the disconnection and entrapment of nonwetting PS domains (i.e., nanospheres, nanocapsules, or capped nanorods). Moreover, PEG is then washed to recover the pristine wettability of PS on the alumina surface; further annealing of the PS nanospheres inside AAO nanopores under vacuum can generate some unique nanostructures, particularly semicylindrical nanorods. © 2011 American Chemical Society

Polarization-induced local pore-wall functionalization for biosensing: from micropore to nanopore.

PubMed

Liu, Jie; Pham, Pascale; Haguet, Vincent; Sauter-Starace, Fabien; Leroy, Loïc; Roget, André; Descamps, Emeline; Bouchet, Aurélie; Buhot, Arnaud; Mailley, Pascal; Livache, Thierry

2012-04-03

The use of biological-probe-modified solid-state pores in biosensing is currently hindered by difficulties in pore-wall functionalization. The surface to be functionalized is small and difficult to target and is usually chemically similar to the bulk membrane. Herein, we demonstrate the contactless electrofunctionalization (CLEF) approach and its mechanism. This technique enables the one-step local functionalization of the single pore wall fabricated in a silica-covered silicon membrane. CLEF is induced by polarization of the pore membrane in an electric field and requires a sandwich-like composition and a conducting or semiconducting core for the pore membrane. The defects in the silica layer of the micropore wall enable the creation of an electric pathway through the silica layer, which allows electrochemical reactions to take place locally on the pore wall. The pore diameter is not a limiting factor for local wall modification using CLEF. Nanopores with a diameter of 200 nm fabricated in a silicon membrane and covered with native silica layer have been successfully functionalized with this method, and localized pore-wall modification was obtained. Furthermore, through proof-of-concept experiments using ODN-modified nanopores, we show that functionalized nanopores are suitable for translocation-based biosensing.

Probing DNA Translocations with Inplane Current Signals in a Graphene Nanoribbon with a Nanopore

PubMed Central

2018-01-01

Many theoretical studies predict that DNA sequencing should be feasible by monitoring the transverse current through a graphene nanoribbon while a DNA molecule translocates through a nanopore in that ribbon. Such a readout would benefit from the special transport properties of graphene, provide ultimate spatial resolution because of the single-atom layer thickness of graphene, and facilitate high-bandwidth measurements. Previous experimental attempts to measure such transverse inplane signals were however dominated by a trivial capacitive response. Here, we explore the feasibility of the approach using a custom-made differential current amplifier that discriminates between the capacitive current signal and the resistive response in the graphene. We fabricate well-defined short and narrow (30 nm × 30 nm) nanoribbons with a 5 nm nanopore in graphene with a high-temperature scanning transmission electron microscope to retain the crystallinity and sensitivity of the graphene. We show that, indeed, resistive modulations can be observed in the graphene current due to DNA translocation through the nanopore, thus demonstrating that DNA sensing with inplane currents in graphene nanostructures is possible. The approach is however exceedingly challenging due to low yields in device fabrication connected to the complex multistep device layout. PMID:29474060

Effect of Graphene with Nanopores on Metal Clusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Hu; Chen, Xianlang; Wang, Lei

Porous graphene, which is a novel type of defective graphene, shows excellent potential as a support material for metal clusters. In this work, the stability and electronic structures of metal clusters (Pd, Ir, Rh) supported on pristine graphene and graphene with different sizes of nanopore were investigated by first-principle density functional theory (DFT) calculations. Thereafter, CO adsorption and oxidation reaction on the Pd-graphene system were chosen to evaluate its catalytic performance. Graphene with nanopore can strongly stabilize the metal clusters and cause a substantial downshift of the d-band center of the metal clusters, thus decreasing CO adsorption. All binding energies,more » d-band centers, and adsorption energies show a linear change with the size of the nanopore: a bigger size of nanopore corresponds to a stronger metal clusters bond to the graphene, lower downshift of the d-band center, and weaker CO adsorption. By using a suitable size nanopore, supported Pd clusters on the graphene will have similar CO and O2 adsorption ability, thus leading to superior CO tolerance. The DFT calculated reaction energy barriers show that graphene with nanopore is a superior catalyst for CO oxidation reaction. These properties can play an important role in instructing graphene-supported metal catalyst preparation to prevent the diffusion or agglomeration of metal clusters and enhance catalytic performance. This work was supported by National Basic Research Program of China (973Program) (2013CB733501), the National Natural Science Foundation of China (NSFC-21176221, 21136001, 21101137, 21306169, and 91334013). D. Mei acknowledges the support from the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. Computing time was granted by the grand challenge of computational catalysis of the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL) and by the National Energy Research Scientific Computing Center (NERSC).« less

Theoretical models for electrochemical impedance spectroscopy and local ζ-potential of unfolded proteins in nanopores

NASA Astrophysics Data System (ADS)

Vitarelli, Michael J.; Talaga, David S.

2013-09-01

Single solid-state nanopores find increasing use for electrical detection and/or manipulation of macromolecules. These applications exploit the changes in signals due to the geometry and electrical properties of the molecular species found within the nanopore. The sensitivity and resolution of such measurements are also influenced by the geometric and electrical properties of the nanopore. This paper continues the development of an analytical theory to predict the electrochemical impedance spectra of nanopores by including the influence of the presence of an unfolded protein using the variable topology finite Warburg impedance model previously published by the authors. The local excluded volume of, and charges present on, the segment of protein sampled by the nanopore are shown to influence the shape and peak frequency of the electrochemical impedance spectrum. An analytical theory is used to relate the capacitive response of the electrical double layer at the surface of the protein to both the charge density at the protein surface and the more commonly measured zeta potential. Illustrative examples show how the theory predicts that the varying sequential regions of surface charge density and excluded volume dictated by the protein primary structure may allow for an impedance-based approach to identifying unfolded proteins.

Nanoporous Thermosets with Percolating Pores from Block Polymers Chemically Fixed above the Order–Disorder Transition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vidil, Thomas; Hampu, Nicholas; Hillmyer, Marc A.

A lamellar diblock polymer combining a cross-linkable segment with a chemically etchable segment was cross-linked above its order–disorder temperature (TODT) to kinetically trap the morphology associated with the fluctuating disordered state. After removal of the etchable block, evaluation of the resulting porous thermoset allows for an unprecedented experimental characterization of the trapped disordered phase. Through a combination of small-angle X-ray scattering, nitrogen sorption, scanning electron microscopy, and electron tomography experiments we demonstrate that the nanoporous structure exhibits a narrow pore size distribution and a high surface to volume ratio and is bicontinuous over a large sample area. Together with themore » processability of the polymeric starting material, the proposed system combines attractive attributes for many advanced applications. In particular, it was used to design new composite membranes for the ultrafiltration of water.« less

Biological Nanopores: Confined Spaces for Electrochemical Single-Molecule Analysis.

PubMed

Cao, Chan; Long, Yi-Tao

2018-02-20

Nanopore sensing is developing into a powerful single-molecule approach to investigate the features of biomolecules that are not accessible by studying ensemble systems. When a target molecule is transported through a nanopore, the ions occupying the pore are excluded, resulting in an electrical signal from the intermittent ionic blockade event. By statistical analysis of the amplitudes, duration, frequencies, and shapes of the blockade events, many properties of the target molecule can be obtained in real time at the single-molecule level, including its size, conformation, structure, charge, geometry, and interactions with other molecules. With the development of the use of α-hemolysin to characterize individual polynucleotides, nanopore technology has attracted a wide range of research interest in the fields of biology, physics, chemistry, and nanoscience. As a powerful single-molecule analytical method, nanopore technology has been applied for the detection of various biomolecules, including oligonucleotides, peptides, oligosaccharides, organic molecules, and disease-related proteins. In this Account, we highlight recent developments of biological nanopores in DNA-based sensing and in studying the conformational structures of DNA and RNA. Furthermore, we introduce the application of biological nanopores to investigate the conformations of peptides affected by charge, length, and dipole moment and to study disease-related proteins' structures and aggregation transitions influenced by an inhibitor, a promoter, or an applied voltage. To improve the sensing ability of biological nanopores and further extend their application to a wider range of molecular sensing, we focus on exploring novel biological nanopores, such as aerolysin and Stable Protein 1. Aerolysin exhibits an especially high sensitivity for the detection of single oligonucleotides both in current separation and duration. Finally, to facilitate the use of nanopore measurements and statistical analysis, we develop an integrated current measurement system and an accurate data processing method for nanopore sensing. The unique geometric structure of a biological nanopore offers a distinct advantage as a nanosensor for single-molecule sensing. The construction of the pore entrance is responsible for capturing the target molecule, while the lumen region determines the translocation process of the single molecule. Since the capture of the target molecule is predominantly diffusion-limited, it is expected that the capture ability of the nanopore toward the target analyte could be effectively enhanced by site-directed mutations of key amino acids with desirable groups. Additionally, changing the side chains inside the wall of the biological nanopore could optimize the geometry of the pore and realize an optimal interaction between the single-molecule interface and the analyte. These improvements would allow for high spatial and current resolution of nanopore sensors, which would ensure the possibility of dynamic study of single biomolecules, including their metastable conformations, charge distributions, and interactions. In the future, data analysis with powerful algorithms will make it possible to automatically and statistically extract detailed information while an analyte translocates through the pore. We conclude that these improvements could have tremendous potential applications for nanopore sensing in the near future.

Chemical synthesis of oriented ferromagnetic LaSr-2 × 4 manganese oxide molecular sieve nanowires

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carretero-Genevrier, Adrián; Gazquez, Jaume; Magen, Cesar

2012-04-25

Here we report a chemical solution based method using nanoporous track-etched polymer templates for producing long and oriented LaSr-2 × 4 manganese oxide molecular sieve nanowires. Scanning transmission electron microscopy and electron energy loss spectroscopy analyses show that the nanowires are ferromagnetic at room temperature, single crystalline, epitaxially grown and self-aligned.

AMN-2: Second International Conference on Advanced Materials and Nanotechnology

DTIC Science & Technology

2005-02-11

radiography 13:45 Geopolymers : nanoparticulate, nanoporous ceramics fabricated under ambient conditions 14:10 Smartening-up carbon: towards chemically...interpenetrating composites 16.15 Nanoscale surface properties of metals treated by electrochemical and physico- chemical methods 16.30 Atomistic strain...sulfonic acid for quantum dot and its characters 16.15 Characterization of photoluminescent CdTe/CdSe composite nanoparticles synthesized by the

Simultaneous Chemical and Refractive Index Sensing in the 1-2.5 μm Near-Infrared Wavelength Range on Nanoporous Gold Disks.

PubMed

Shih, Wei-Chuan; Santos, Greggy M; Zhao, Fusheng; Zenasni, Oussama; Arnob, Md Masud Parvez

2016-07-13

Near-infrared (NIR) absorption spectroscopy provides molecular and chemical information based on overtones and combination bands of the fundamental vibrational modes in the infrared wavelengths. However, the sensitivity of NIR absorption measurement is limited by the generally weak absorption and the relatively poor detector performance compared to other wavelength ranges. To overcome these barriers, we have developed a novel technique to simultaneously obtain chemical and refractive index sensing in 1-2.5 μm NIR wavelength range on nanoporous gold (NPG) disks, which feature high-density plasmonic hot-spots of localized electric field enhancement. For the first time, surface-enhanced near-infrared absorption (SENIRA) spectroscopy has been demonstrated for high sensitivity chemical detection. With a self-assembled monolayer (SAM) of octadecanethiol (ODT), an enhancement factor (EF) of up to ∼10(4) has been demonstrated for the first C-H combination band at 2400 nm using NPG disk with 600 nm diameter. Together with localized surface plasmon resonance (LSPR) extinction spectroscopy, simultaneous sensing of sample refractive index has been achieved for the first time. The performance of this technique has been evaluated using various hydrocarbon compounds and crude oil samples.

Real-time detection of BRAF V600E mutation from archival hairy cell leukemia FFPE tissue by nanopore sequencing.

PubMed

Vacca, Davide; Cancila, Valeria; Gulino, Alessandro; Lo Bosco, Giosuè; Belmonte, Beatrice; Di Napoli, Arianna; Florena, Ada Maria; Tripodo, Claudio; Arancio, Walter

2018-02-01

The MinION is a miniaturized high-throughput next generation sequencing platform of novel conception. The use of nucleic acids derived from formalin-fixed paraffin-embedded samples is highly desirable, but their adoption for molecular assays is hurdled by the high degree of fragmentation and by the chemical-induced mutations stemming from the fixation protocols. In order to investigate the suitability of MinION sequencing on formalin-fixed paraffin-embedded samples, the presence and frequency of BRAF c.1799T > A mutation was investigated in two archival tissue specimens of Hairy cell leukemia and Hairy cell leukemia Variant. Despite the poor quality of the starting DNA, BRAF mutation was successfully detected in the Hairy cell leukemia sample with around 50% of the reads obtained within 2 h of the sequencing start. Notably, the mutational burden of the Hairy cell leukemia sample as derived from nanopore sequencing proved to be comparable to a sensitive method for the detection of point mutations, namely the Digital PCR, using a validated assay. Nanopore sequencing can be adopted for targeted sequencing of genetic lesions on critical DNA samples such as those extracted from archival routine formalin-fixed paraffin-embedded samples. This result let speculating about the possibility that the nanopore sequencing could be trustably adopted for the real-time targeted sequencing of genetic lesions. Our report opens the window for the adoption of nanopore sequencing in molecular pathology for research and diagnostics.

Cross-Scale Molecular Analysis of Chemical Heterogeneity in Shale Rocks

DOE PAGES

Hao, Zhao; Bechtel, Hans A.; Kneafsey, Timothy; ...

2018-02-07

The organic and mineralogical heterogeneity in shale at micrometer and nanometer spatial scales contributes to the quality of gas reserves, gas flow mechanisms and gas production. Here, we demonstrate two molecular imaging approaches based on infrared spectroscopy to obtain mineral and kerogen information at these mesoscale spatial resolutions in large-sized shale rock samples. The first method is a modified microscopic attenuated total reflectance measurement that utilizes a large germanium hemisphere combined with a focal plane array detector to rapidly capture chemical images of shale rock surfaces spanning hundreds of micrometers with micrometer spatial resolution. The second method, synchrotron infrared nano-spectroscopy,more » utilizes a metallic atomic force microscope tip to obtain chemical images of micrometer dimensions but with nanometer spatial resolution. This chemically "deconvoluted" imaging at the nano-pore scale is then used to build a machine learning model to generate a molecular distribution map across scales with a spatial span of 1000 times, which enables high-throughput geochemical characterization in greater details across the nano-pore and micro-grain scales and allows us to identify co-localization of mineral phases with chemically distinct organics and even with gas phase sorbents. Finally, this characterization is fundamental to understand mineral and organic compositions affecting the behavior of shales.« less

Cross-Scale Molecular Analysis of Chemical Heterogeneity in Shale Rocks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hao, Zhao; Bechtel, Hans A.; Kneafsey, Timothy

The organic and mineralogical heterogeneity in shale at micrometer and nanometer spatial scales contributes to the quality of gas reserves, gas flow mechanisms and gas production. Here, we demonstrate two molecular imaging approaches based on infrared spectroscopy to obtain mineral and kerogen information at these mesoscale spatial resolutions in large-sized shale rock samples. The first method is a modified microscopic attenuated total reflectance measurement that utilizes a large germanium hemisphere combined with a focal plane array detector to rapidly capture chemical images of shale rock surfaces spanning hundreds of micrometers with micrometer spatial resolution. The second method, synchrotron infrared nano-spectroscopy,more » utilizes a metallic atomic force microscope tip to obtain chemical images of micrometer dimensions but with nanometer spatial resolution. This chemically "deconvoluted" imaging at the nano-pore scale is then used to build a machine learning model to generate a molecular distribution map across scales with a spatial span of 1000 times, which enables high-throughput geochemical characterization in greater details across the nano-pore and micro-grain scales and allows us to identify co-localization of mineral phases with chemically distinct organics and even with gas phase sorbents. Finally, this characterization is fundamental to understand mineral and organic compositions affecting the behavior of shales.« less

Zeolitic imidazolate framework-coated acoustic sensors for room temperature detection of carbon dioxide and methane

DOE PAGES

Devkota, Jagannath; Kim, Ki-Joong; Ohodnicki, Paul R.; ...

2018-01-01

The integration of nanoporous materials such as metal organic frameworks (MOFs) with sensitive transducers can result in robust sensing platforms for monitoring gases and chemical vapors for a range of applications.

Electrochemical fabrication of SrTiO3 nanowires with nanoporous alumina template.

PubMed

Kang, Jinwook; Ryu, Jaemin; Ko, Eunseong; Tak, Yongsug

2007-11-01

Strontium titanate nanowires were electrochemically synthesized with nanoporous alumina template. Both chemical and electrical variables such as electrolyte pH, temperature, and current waveform were modulated to investigate the synthesis process of SrTiO3 nanowires. Superimposed cathodic pulse and diffusion time accelerated the growth of SrTiO3 nanowires, which suggested that the concentration of H+ and Sr2+ ion inside alumina template had a strong influence on the formation of SrTiO3 nanowires. Morphology and crystallinity of SrTiO3 nanowires were investigated with scanning electron microscope, X-ray diffractometer and energy dispersive X-ray spectroscopy.

A Voltage-Responsive Free-Blockage Controlled-Release System Based on Hydrophobicity Switching.

PubMed

Jiao, Xiangyu; Sun, Ruijuan; Cheng, Yaya; Li, Fengyu; Du, Xin; Wen, Yongqiang; Song, Yanlin; Zhang, Xueji

2017-05-19

Controlled-release systems based on mesoporous silica nanomaterials (MSNs) have drawn great attention owing to their potential biomedical applications. Various switches have been designed to control the release of cargoes through the construction of physical blocking units on the surface of MSNs. However, such physical blockages are limited by poor sealing ability and low biocompatibility, and most of them lack closure ability. Herein, a voltage-responsive controlled-release system was constructed by functionalizing the nanopore of MSNs with ferrocene. The system realized free-blockage controlled release and achieved pulsatile release. The nanopores of the ferrocene-functionalized MSNs were hydrophobic enough to prevent invasion of the solution. Once a suitable voltage was applied, the nanopores became hydrophilic, which was followed by invasion of the solution and the release of the cargos. Moreover, pulsatile release was realized, which avoided unexpected release after the stimulus disappeared. Thus, we believe that our studies provide new insight into highly effective blockage for MSNs. Furthermore, the voltage-responsive release system is expected to find use in electrical stimulation combination therapy and bioelectricity-responsive release. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermally and chemically responsive nanoporous materials for efficient capture of fission product gases.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stroeve, Pieter; Faller, Roland

The objective of this project was to develop robust, high-efficiency materials for capture of fission product gases such as He, Xe and Kr in scenarios relevant for both reactor fuels and reprocessing operations. The relevant environments are extremely harsh, encompassing temperatures up to 1500 °C, high levels of radiation, as well as potential exposures to highly-reactive chemicals such as nitric acid and organic solvents such as kerosene. The requirement for nanostructured capture materials is driven in part by the very short (few micron) diffusion distances for product gases in nuclear fuel. We achieved synthesis, characterization and detailed modeling of themore » materials. Although not all materials reviewed in this report will be feasible for the ultimate goal of integration in nuclear fuel, nevertheless each material studied has particular properties which will enable an optimized material to be efficiently developed and characterized.« less

Silicon-on-insulator based nanopore cavity arrays for lipid membrane investigation.

PubMed

Buchholz, K; Tinazli, A; Kleefen, A; Dorfner, D; Pedone, D; Rant, U; Tampé, R; Abstreiter, G; Tornow, M

2008-11-05

We present the fabrication and characterization of nanopore microcavities for the investigation of transport processes in suspended lipid membranes. The cavities are situated below the surface of silicon-on-insulator (SOI) substrates. Single cavities and large area arrays were prepared using high resolution electron-beam lithography in combination with reactive ion etching (RIE) and wet chemical sacrificial underetching. The locally separated compartments have a circular shape and allow the enclosure of picoliter volume aqueous solutions. They are sealed at their top by a 250 nm thin Si membrane featuring pores with diameters from 2 µm down to 220 nm. The Si surface exhibits excellent smoothness and homogeneity as verified by AFM analysis. As biophysical test system we deposited lipid membranes by vesicle fusion, and demonstrated their fluid-like properties by fluorescence recovery after photobleaching. As clearly indicated by AFM measurements in aqueous buffer solution, intact lipid membranes successfully spanned the pores. The nanopore cavity arrays have potential applications in diagnostics and pharmaceutical research on transmembrane proteins.

Controlled release of astaxanthin from nanoporous silicified-phospholipids assembled boron nitride complex for cosmetic applications

NASA Astrophysics Data System (ADS)

Lee, Hye Sun; Sung, Dae Kyung; Kim, Sung Hyun; Choi, Won Il; Hwang, Ee Tag; Choi, Doo Jin; Chang, Jeong Ho

2017-12-01

Nanoporous silicified-phospholipids assembled boron nitride (nSPLs@BN) powder was prepared and demonstrated for use in controlled release of anti-oxidant astaxanthin (AX) as a cosmetic application. The nanoporous silicified phospholipids (nSPLs) were obtained by the silicification with tetraethyl orthosilicate (TEOS) of the hydrophilic region of phospholipid bilayers. This process involved the co-assembly of chemically active phospholipid bilayers within the porous silica matrix. In addition, nSPLs@BN was characterized using several analytical techniques and tested to assess their efficiency as drug delivery systems. We calculated the maximum release amounts as a function of time and various pH. The release rate of AX from the nSPLs@BN for the initial 24 h was 10.7 μmol/(h mg) at pH 7.4. Furthermore, we determined the antioxidant activity (KD) for the released AX with DPPH (1,1-diphenyl-2-picryl-hydrazyl) radical and the result was 34.6%.

Nanoair-bridged lateral overgrowth of GaN on ordered nanoporous GaN template

NASA Astrophysics Data System (ADS)

Wang, Y. D.; Zang, K. Y.; Chua, S. J.; Tripathy, S.; Chen, P.; Fonstad, C. G.

2005-12-01

We report the growth of high-quality GaN epilayers on an ordered nanoporous GaN template by metalorganic chemical vapor deposition. The nanopores in GaN template were created by inductively coupled plasma etching using anodic aluminum oxide film as an etch mask. The average pore diameter and interpore distance is about 65 and 110nm, respectively. Subsequent overgrowth of GaN first begins at the GaN crystallite surface between the pores, and then air-bridge-mediated lateral overgrowth leads to the formation of the continuous layer. Microphotoluminescence and micro-Raman measurements show improved optical properties and significant strain relaxation in the overgrown layer when compared to GaN layer of same thickness simultaneously grown on sapphire without any template. Similar to conventional epitaxial lateral overgrown GaN, such overgrown GaN on a nanopatterned surface would also serve as a template for the growth of ultraviolet-visible light-emitting III-nitride devices.

Investigation of thermal conduction in symmetric and asymmetric nanoporous structures

NASA Astrophysics Data System (ADS)

Yu, Ziqi; Ferrer-Argemi, Laia; Lee, Jaeho

2017-12-01

Nanoporous structures with a critical dimension comparable to or smaller than the phonon mean free path have demonstrated significant thermal conductivity reductions that are attractive for thermoelectric applications, but the presence of various geometric parameters complicates the understanding of governing mechanisms. Here, we use a ray tracing technique to investigate phonon boundary scattering phenomena in Si nanoporous structures of varying pore shapes, pore alignments, and pore size distributions, and identify mechanisms that are primarily responsible for thermal conductivity reductions. Our simulation results show that the neck size, or the smallest distance between nearest pores, is the key parameter in understanding nanoporous structures of varying pore shapes and the same porosities. When the neck size and the porosity are both identical, asymmetric pore shapes provide a lower thermal conductivity compared with symmetric pore shapes, due to localized heat fluxes. Asymmetric nanoporous structures show possibilities of realizing thermal rectification even with fully diffuse surface boundaries, in which optimal arrangements of triangular pores show a rectification ratio up to 13 when the injection angles are optimally controlled. For symmetric nanoporous structures, hexagonal-lattice pores achieve larger thermal conductivity reductions than square-lattice pores due to the limited line of sight for phonons. We also show that nanoporous structures of alternating pore size distributions from large to small pores yield a lower thermal conductivity compared with those of uniform pore size distributions in the given porosity. These findings advance the understanding of phonon boundary scattering phenomena in complex geometries and enable optimal designs of artificial nanostructures for thermoelectric energy harvesting and solid-state cooling systems.

Sorption behavior of Eu(III) from an aqueous solution onto modified hydroxyapatite: kinetics, modeling and thermodynamics.

PubMed

Gad, H M H; Youssef, M A

2017-08-16

Nano-pore hydroxyapatite (HAP) was prepared using physical activation of raw and chemically modified [using Acid; HNO 3 (HAPA) or Base; NaOH (HAPB)] bone char (BC) by heating at 900°C for 1 hr to obtain HAP9, HAPA9 and HAPB9, respectively. Investigation the effects of thermal and chemical treatment of prepared nano-hydroxyapatite on elemental analysis, FTIR, scanning electron microscopy, surface area and consequently, the sorption behavior of Eu (III) ions onto the prepared nano-pore hydroxyapatite. Batch adsorption technique was used and the obtained results revealed that the optimum pH = 5.0. The % removal of europium (III) using HAPA9 and HAPB9 reach to 100% within 15 min, while HAP9 after 180 min and the pseudo-second-order was found to be fit to the experimental data. According to Langmuir model, the maximum sorption capacities (q m ) were 123.8, 384.9 and 74.2 mg g -1 for HAP9, HAPA9 and HAPB9, respectively. The reaction is spontaneous according to ΔG° value. HCl (0.5 M) was the most efficient desorbing agent for recovery of Eu(III) and regeneration of adsorbents. Finally, nano-pore hydroxyapatite (HAP) was low cost and very effective adsorbent for sorption or recovery of Eu(III) from aqueous solutions and remediation of environmental pollution.

Characterization of Pressure Transients Generated by Nanosecond Electrical Pulse (nsEP) Exposure.

PubMed

Roth, Caleb C; Barnes, Ronald A; Ibey, Bennett L; Beier, Hope T; Christopher Mimun, L; Maswadi, Saher M; Shadaram, Mehdi; Glickman, Randolph D

2015-10-09

The mechanism(s) responsible for the breakdown (nanoporation) of cell plasma membranes after nanosecond pulse (nsEP) exposure remains poorly understood. Current theories focus exclusively on the electrical field, citing electrostriction, water dipole alignment and/or electrodeformation as the primary mechanisms for pore formation. However, the delivery of a high-voltage nsEP to cells by tungsten electrodes creates a multitude of biophysical phenomena, including electrohydraulic cavitation, electrochemical interactions, thermoelastic expansion, and others. To date, very limited research has investigated non-electric phenomena occurring during nsEP exposures and their potential effect on cell nanoporation. Of primary interest is the production of acoustic shock waves during nsEP exposure, as it is known that acoustic shock waves can cause membrane poration (sonoporation). Based on these observations, our group characterized the acoustic pressure transients generated by nsEP and determined if such transients played any role in nanoporation. In this paper, we show that nsEP exposures, equivalent to those used in cellular studies, are capable of generating high-frequency (2.5 MHz), high-intensity (>13 kPa) pressure transients. Using confocal microscopy to measure cell uptake of YO-PRO®-1 (indicator of nanoporation of the plasma membrane) and changing the electrode geometry, we determined that acoustic waves alone are not responsible for poration of the membrane.

Uncertainty Quantification of Nonlinear Electrokinetic Response in a Microchannel-Membrane Junction

NASA Astrophysics Data System (ADS)

Alizadeh, Shima; Iaccarino, Gianluca; Mani, Ali

2015-11-01

We have conducted uncertainty quantification (UQ) for electrokinetic transport of ionic species through a hybrid microfluidic system using different probabilistic techniques. The system of interest is an H-configuration consisting of two parallel microchannels that are connected via a nafion junction. This system is commonly used for ion preconcentration and stacking by utilizing a nonlinear response at the channel-nafion junction that leads to deionization shocks. In this work, the nafion medium is modeled as many parallel nano-pores where, the nano-pore diameter, nafion porosity, and surface charge density are independent random variables. We evaluated the resulting uncertainty on the ion concentration fields as well as the deionization shock location. The UQ methods predicted consistent statistics for the outputs and the results revealed that the shock location is weakly sensitive to the nano-pore surface charge and primarily driven by nano-pore diameters. The present study can inform the design of electrokinetic networks with increased robustness to natural manufacturing variability. Applications include water desalination and lab-on-a-chip systems. Shima is a graduate student in the department of Mechanical Engineering at Stanford University. She received her Master's degree from Stanford in 2011. Her research interests include Electrokinetics in porous structures and high performance computing.

Nanolock-Nanopore Facilitated Digital Diagnostics of Cancer Driver Mutation in Tumor Tissue.

PubMed

Wang, Yong; Tian, Kai; Shi, Ruicheng; Gu, Amy; Pennella, Michael; Alberts, Lindsey; Gates, Kent S; Li, Guangfu; Fan, Hongxin; Wang, Michael X; Gu, Li-Qun

2017-07-28

Cancer driver mutations are clinically significant biomarkers. In precision medicine, accurate detection of these oncogenic changes in patients would enable early diagnostics of cancer, individually tailored targeted therapy, and precise monitoring of treatment response. Here we investigated a novel nanolock-nanopore method for single-molecule detection of a serine/threonine protein kinase gene BRAF V600E mutation in tumor tissues of thyroid cancer patients. The method lies in a noncovalent, mutation sequence-specific nanolock. We found that the nanolock formed on the mutant allele/probe duplex can separate the duplex dehybridization procedure into two sequential steps in the nanopore. Remarkably, this stepwise unzipping kinetics can produce a unique nanopore electric marker, with which a single DNA molecule of the cancer mutant allele can be unmistakably identified in various backgrounds of the normal wild-type allele. The single-molecule sensitivity for mutant allele enables both binary diagnostics and quantitative analysis of mutation occurrence. In the current configuration, the method can detect the BRAF V600E mutant DNA lower than 1% in the tumor tissues. The nanolock-nanopore method can be adapted to detect a broad spectrum of both transversion and transition DNA mutations, with applications from diagnostics to targeted therapy.

Stress-induced chemical detection using flexible metal-organic frameworks.

PubMed

Allendorf, Mark D; Houk, Ronald J T; Andruszkiewicz, Leanne; Talin, A Alec; Pikarsky, Joel; Choudhury, Arnab; Gall, Kenneth A; Hesketh, Peter J

2008-11-05

In this work we demonstrate the concept of stress-induced chemical detection using metal-organic frameworks (MOFs) by integrating a thin film of the MOF HKUST-1 with a microcantilever surface. The results show that the energy of molecular adsorption, which causes slight distortions in the MOF crystal structure, can be converted to mechanical energy to create a highly responsive, reversible, and selective sensor. This sensor responds to water, methanol, and ethanol vapors, but yields no response to either N2 or O2. The magnitude of the signal, which is measured by a built-in piezoresistor, is correlated with the concentration and can be fitted to a Langmuir isotherm. Furthermore, we show that the hydration state of the MOF layer can be used to impart selectivity to CO2. Finally, we report the first use of surface-enhanced Raman spectroscopy to characterize the structure of a MOF film. We conclude that the synthetic versatility of these nanoporous materials holds great promise for creating recognition chemistries to enable selective detection of a wide range of analytes.

Selective and reversible ammonia gas detection with nanoporous film functionalized silicon photonic micro-ring resonator.

PubMed

Yebo, Nebiyu A; Sree, Sreeprasanth Pulinthanathu; Levrau, Elisabeth; Detavernier, Christophe; Hens, Zeger; Martens, Johan A; Baets, Roel

2012-05-21

Portable, low cost and real-time gas sensors have a considerable potential in various biomedical and industrial applications. For such applications, nano-photonic gas sensors based on standard silicon fabrication technology offer attractive opportunities. Deposition of high surface area nano-porous coatings on silicon photonic sensors is a means to achieve selective, highly sensitive and multiplexed gas detection on an optical chip. Here we demonstrate selective and reversible ammonia gas detection with functionalized silicon-on-insulator optical micro-ring resonators. The micro-ring resonators are coated with acidic nano-porous aluminosilicate films for specific ammonia sensing, which results in a reversible response to NH(3)with selectivity relative to CO(2). The ammonia detection limit is estimated at about 5 ppm. The detectors reach a steady response to NH(3) within 30 and return to their base level within 60 to 90 seconds. The work opens perspectives on development of nano-photonic sensors for real-time, non-invasive, low cost and light weight biomedical and industrial sensing applications.

Three-Dimensional Nanoporous Fe2O3/Fe3C-Graphene Heterogeneous Thin Films for Lithium-Ion Batteries

PubMed Central

2015-01-01

Three-dimensional self-organized nanoporous thin films integrated into a heterogeneous Fe2O3/Fe3C-graphene structure were fabricated using chemical vapor deposition. Few-layer graphene coated on the nanoporous thin film was used as a conductive passivation layer, and Fe3C was introduced to improve capacity retention and stability of the nanoporous layer. A possible interfacial lithium storage effect was anticipated to provide additional charge storage in the electrode. These nanoporous layers, when used as an anode in lithium-ion batteries, deliver greatly enhanced cyclability and rate capacity compared with pristine Fe2O3: a specific capacity of 356 μAh cm–2 μm–1 (3560 mAh cm–3 or ∼1118 mAh g–1) obtained at a discharge current density of 50 μA cm–2 (∼0.17 C) with 88% retention after 100 cycles and 165 μAh cm–2 μm–1 (1650 mAh cm–3 or ∼518 mAh g–1) obtained at a discharge current density of 1000 μA cm–2 (∼6.6 C) for 1000 cycles were achieved. Meanwhile an energy density of 294 μWh cm–2 μm–1 (2.94 Wh cm–3 or ∼924 Wh kg–1) and power density of 584 μW cm–2 μm–1 (5.84 W cm–3 or ∼1834 W kg–1) were also obtained, which may make these thin film anodes promising as a power supply for micro- or even nanosized portable electronic devices. PMID:24669862

Parametric study of thin film evaporation from nanoporous membranes

NASA Astrophysics Data System (ADS)

Wilke, Kyle L.; Barabadi, Banafsheh; Lu, Zhengmao; Zhang, TieJun; Wang, Evelyn N.

2017-10-01

The performance and lifetime of advanced electronics are often dictated by the ability to dissipate heat generated within the device. Thin film evaporation from nanoporous membranes is a promising thermal management approach, which reduces the thermal transport distance across the liquid film while also providing passive capillary pumping of liquid to the evaporating interface. In this work, we investigated the dependence of thin film evaporation from nanoporous membranes on a variety of geometric parameters. Anodic aluminum oxide membranes were used as experimental templates, where pore radii of 28-75 nm, porosities of 0.1-0.35, and meniscus locations down to 1 μm within the pore were tested. We demonstrated different heat transfer regimes and observed more than an order of magnitude increase in dissipated heat flux by operating in the pore-level evaporation regime. The pore diameter had little effect on pore-level evaporation performance due to the negligible conduction resistance from the pore wall to the evaporating interface. The dissipated heat flux scaled with porosity as the evaporative area increased. Furthermore, moving the meniscus as little as 1 μm into the pore decreased the dissipated heat flux by more than a factor of two due to the added resistance to vapor escaping the pore. The experimental results elucidate thin film evaporation from nanopores and confirm findings of recent modeling efforts. This work also provides guidance for the design of future thin film evaporation devices for advanced thermal management. Furthermore, evaporation from nanopores is relevant to water purification, chemical separations, microfluidics, and natural processes such as transpiration.

An ultrasensitive bio-surrogate for nanoporous filter membrane performance metrology directed towards contamination control in microlithography applications

NASA Astrophysics Data System (ADS)

Ahmad, Farhan; Mish, Barbara; Qiu, Jian; Singh, Amarnauth; Varanasi, Rao; Bedford, Eilidh; Smith, Martin

2016-03-01

Contamination tolerances in semiconductor manufacturing processes have changed dramatically in the past two decades, reaching below 20 nm according to the guidelines of the International Technology Roadmap for Semiconductors. The move to narrower line widths drives the need for innovative filtration technologies that can achieve higher particle/contaminant removal performance resulting in cleaner process fluids. Nanoporous filter membrane metrology tools that have been the workhorse over the past decade are also now reaching limits. For example, nanoparticle (NP) challenge testing is commonly applied for assessing particle retention performance of filter membranes. Factors such as high NP size dispersity, low NP detection sensitivity, and high NP particle-filter affinity impose challenges in characterizing the next generation of nanoporous filter membranes. We report a novel bio-surrogate, 5 nm DNA-dendrimer conjugate for evaluating particle retention performance of nanoporous filter membranes. A technique capable of single molecule detection is employed to detect sparse concentration of conjugate in filter permeate, providing >1000- fold higher detection sensitivity than any existing 5 nm-sized particle enumeration technique. This bio-surrogate also offers narrow size distribution, high stability and chemical tunability. This bio-surrogate can discriminate various sub-15 nm pore-rated nanoporous filter membranes based on their particle retention performance. Due to high bio-surrogate detection sensitivity, a lower challenge concentration of bio-surrogate (as compared to other NPs of this size) can be used for filter testing, providing a better representation of customer applications. This new method should provide better understanding of the next generation filter membranes for removing defect-causing contaminants from lithography processes.

Synthesis and characterization of pure strontium apatite particles and nanoporous scaffold prepared by dextrose-templated method

NASA Astrophysics Data System (ADS)

Ma, Xiaoyu; Liu, Yongjia; Zhu, Bangshang

2018-02-01

Strontium shows an increasing interest on bone formation and bone resorption prevention. Here, pure apatite strontium (Ap-SrOH) [Sr5(PO4)3(OH), strontium hydroxyapatite] particles were prepared by the precipitation method using Sr(NO3)2 · 6H2O and (NH4)2HPO4 as reagents. Scanning electron microscope, transmission electron microscope combined with electron diffraction, X-ray diffraction, Fourier transform infrared spectra (FTIR), variable temperature FTIR and thermo gravimetric analysis were employed to evaluate the crystalline structure, chemical composition, and thermal stability of the Ap-SrOH particles. The results show that phase pure Ap-SrOH particles were prepared by wet precipitation. The obtained Ap-SrOH particles are single crystal in phase structure, they have hexagonal fusiform shape, and their size is about 30-180 nm in diameter, and 0.4-2.5 μm in length. The cell MTT assay evaluations indicate that Ap-SrOH particles have very low cytotoxicity. Furthermore, nanoporous Ap-SrOH scaffolds were synthesized by anhydrous dextrose template method. After mixed 5-10 wt% of anhydrous dextrose with Ap-SrOH particles, pressed into discs, and sintered in microwave muffle furnace at 600 °C, the scaffolds with both nanoporous and nanotopography were formed. Cell culture of MC3T3-E1 osteoblasts in vitro show cells grow well on nanoporous Ap-SrOH scaffold. Therefore, Ap-SrOH particles and their nanoporous scaffolds are promising biomaterials for bone repairing and bone disease (e.g. osteoporosis) healing.

Electrochemical properties of nanostructured porous gold electrodes in biofouling solutions.

PubMed

Patel, Jay; Radhakrishnan, Logudurai; Zhao, Bo; Uppalapati, Badharinadh; Daniels, Rodney C; Ward, Kevin R; Collinson, Maryanne M

2013-12-03

The effect of electrode porosity on the electrochemical response of redox active molecules (potassium ferricyanide, ruthenium(III) hexammine, and ferrocene methanol) in the presence of bovine serum albumin or fibrinogen was studied at macroporous (pore diameter: 1200 nm), hierarchical (1200/60 nm), and nanoporous (<50 nm) gold. These electrodes were prepared using standard templating or dealloying techniques, and cyclic voltammetry (CV) was utilized to evaluate the effect of protein adsorption on the electron transfer of the diffusing redox probes. Following exposure to albumin (or fibrinogen) under near neutral pH conditions, planar gold electrodes showed an immediate reduction in Faradaic peak current and increase in peak splitting for potassium ferricyanide. The rate at which the CV curves changed was highly dependent on the morphology of the electrode. For example, the time required for the Faradaic current to drop to one-half of its original value was 3, 12, and 38 min for planar gold, macroporous gold, and hierarchical gold, respectively. Remarkably, for nanoporous gold, only a few percent drop in the peak Faradaic current was observed after an hour in solution. A similar suppression in the voltammetry at planar gold was also noted for ruthenium hexammine at pH 3 after exposure to albumin for several hours. At nanoporous gold, no significant loss in response was observed. The order of performance of the electrodes as judged by their ability to efficiently transfer electrons in the presence of biofouling agents tracked porosity with the electrode having the smallest pore size and largest surface area, providing near ideal results. Nanoporous gold electrodes when immersed in serum or heparinized blood containing potassium ferricyanide showed ideal voltammetry while significant fouling was evident in the electrochemical response at planar gold. The small nanopores in this 3D open framework are believed to restrict the transport of large biomolecules, thus minimizing passivation of the inner surfaces while permitting access to small redox probes to efficiently exchange electrons.

Transport mechanisms in nanopores and nanochannels: Can we mimic nature?

DOE PAGES

Tagliazucchi, Mario; Szleifer, Igal

2014-11-03

The last few years have witnessed major advancements in the synthesis, modification, characterization and modeling of nanometer-size solid-state channels and pores. Future applications in sensing, energy conversion and purification technologies will critically rely on qualitative improvements in the control over the selectivity, directionality and responsiveness of these nanochannels and nanopores. It is not surprising, therefore, that researchers in the field seek inspiration in biological ion channels and ion pumps, paradigmatic examples of transport selectivity. This work reviews our current fundamental understanding of the mechanisms of transport of ions and larger cargoes through nanopores and nanochannels by examining recent experimental andmore » theoretical work. It is argued that that structure and transport in biological channels and polyelectrolyte-modified synthetic nanopores are strongly coupled: the structure dictates transport and transport affects the structure. We compare synthetic and biological systems throughout this review to conclude that while they present interesting similarities, they also have striking differences.« less

Short infrared (IR) laser pulses can induce nanoporation

NASA Astrophysics Data System (ADS)

Roth, Caleb C.; Barnes, Ronald A.; Ibey, Bennett L.; Glickman, Randolph D.; Beier, Hope T.

2016-03-01

Short infrared (IR) laser pulses on the order of hundreds of microseconds to single milliseconds with typical wavelengths of 1800-2100 nm, have shown the capability to reversibly stimulate action potentials (AP) in neuronal cells. While the IR stimulation technique has proven successful for several applications, the exact mechanism(s) underlying the AP generation has remained elusive. To better understand how IR pulses cause AP stimulation, we determined the threshold for the formation of nanopores in the plasma membrane. Using a surrogate calcium ion, thallium, which is roughly the same shape and charge, but lacks the biological functionality of calcium, we recorded the flow of thallium ions into an exposed cell in the presence of a battery of channel antagonists. The entry of thallium into the cell indicated that the ions entered via nanopores. The data presented here demonstrate a basic understanding of the fundamental effects of IR stimulation and speculates that nanopores, formed in response to the IR exposure, play an upstream role in the generation of AP.

Monitoring tetracycline through a solid-state nanopore sensor

NASA Astrophysics Data System (ADS)

Zhang, Yuechuan; Chen, Yanling; Fu, Yongqi; Ying, Cuifeng; Feng, Yanxiao; Huang, Qimeng; Wang, Chao; Pei, De-Sheng; Wang, Deqiang

2016-06-01

Antibiotics as emerging environmental contaminants, are widely used in both human and veterinary medicines. A solid-state nanopore sensing method is reported in this article to detect Tetracycline, which is based on Tet-off and Tet-on systems. rtTA (reverse tetracycline-controlled trans-activator) and TRE (Tetracycline Responsive Element) could bind each other under the action of Tetracycline to form one complex. When the complex passes through nanopores with 8 ~ 9 nanometers in diameter, we could detect the concentrations of Tet from 2 ng/mL to 2000 ng/mL. According to the Logistic model, we could define three growth zones of Tetracycline for rtTA and TRE. The slow growth zone is 0-39.5 ng/mL. The rapid growth zone is 39.5-529.7 ng/mL. The saturated zone is > 529.7 ng/mL. Compared to the previous methods, the nanopore sensor could detect and quantify these different kinds of molecule at the single-molecule level.

Science of Nanofluidics and Energy Conversion

NASA Astrophysics Data System (ADS)

Xu, Baoxing

The emerging subject of nanofluidics, where solids and fluids interact closely at the nanoscale, has exhibited radically different from their macroscopic counterparts (and sometimes counterintuitive), and yet relatively less explored. On the other hand, the resulting unique properties may contribute to a number of innovative functions with fascinating applications. Among various exciting potential applications, an important and ever expanding one is to provide alternative solutions to energy conversion with high efficiency, including energy absorption, actuation and harvesting. In this dissertation, we first report a novel protection mechanism of energy capture through which an intensive impact or blast energy can be effectively mitigated based on a nonwetting liquid-nanoporous material system. The captured energy is stored in nanopores in the form of potential energy of intercalated water molecules for a while, and not necessarily converted to other forms of energy (e.g. heat). At unloading stage, the captured energy will be released gradually due to the hydrophobic inner surfaces of nanopores through the diffusion of water molecules out of nanopores, thus making this system reusable. Several key controlling factors including impacting velocity, nanopore size, nanopore structure, and liquid phase have been investigated on the capacity of energy capture. The molecular mechanism is elucidated through the study of water molecular distributions inside nanpores. These molecular dynamic (MD) findings are quantitatively verified by a parallel blast experiment on a zeolite/water system. During the transport of confined liquid molecules, the friction resistance exerted by solid atoms of nanopores to liquid molecules will dissipate part of energy, and is highly dependent of temperature of liquid molecules and wall morphology of nanopores. Using MD simulations, the effects of temperature and wall roughness on the transport resistance of water molecules inside nanopores are investigated in Chapter 3. The effective shear stress and nominal viscosity that dominate the nanofluidic transport resistance are extracted and coupled with the nanopore size, transport rate, and liquid property. The molecular-level mechanisms are revealed through the study of the density profile and hydrogen bonding of confined liquid molecules. A parallel experiment on a nanoporous carbon-liquid system is carried out and qualitatively verifies MD findings. Motived by the well-known thermo- and electro-capillary effect, Chapter 4 and Chapter 5 present a conceptual design of thermal and electric actuation system by adjusting the relative hydrophobicity of a liquid-nanoporous system through a thermal and electric field, respectively. The thermally and electrically dependent infiltration behaviors of liquids into nanopores are analyzed by using MD simulations. The fundamental molecular characteristics, including the density profile, contact angle, and surface tension of the confined liquid molecules, are examined to reveal underlying mechanisms. The energy density, power density, and efficiency of both thermal and electric actuation systems are explored and their variations with pore size, solid phase, and liquid phase are evaluated. Thermally and electrically controlled infiltration experiments on a zeolite-water /electrolyte solution system are performed accordingly to qualitatively validate these findings. These energy actuation systems can also become high density thermal or electric storage devices with proper designs. Energy harvesting by the flow of a hydrochloric acid-water solution through a nanopore is explored using atomistic simulations in the last chapter. Through ion configurations near the pore wall, an averaged ion drifting velocity is determined, and the induced voltage along the axial direction is obtained as a function of key material parameters, including the applied flow rate, environmental temperature, solution concentration and nanopore size. The molecular mechanism of ion hopping and motion is revealed. This study shed light on harvesting wasted thermal and mechanical energy from ambient environmental sources such as wasted heat in power plants. Nanofluidics is a novel and thriving research area, whose couplings with other disciplines such as material, mechanical, physical, chemical, electrical engineering are open.

Multiscale Characterization of Structural Compositional and Textural Heterogeneity of Nano-porous Geomaterials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoon, Hongkyu

The purpose of the project was to perform multiscale characterization of low permeability rocks to determine the effect of physical and chemical heterogeneity on the poromechanical and flow responses of shales and carbonate rocks with a broad range of physical and chemical heterogeneity . An integrated multiscale imaging of shale and carbonate rocks from nanometer to centimeter scales include s dual focused ion beam - scanning electron microscopy (FIB - SEM) , micro computed tomography (micro - CT) , optical and confocal microscopy, and 2D and 3D energy dispersive spectroscopy (EDS). In addition, mineralogical mapping and backscattered imaging with nanoindentationmore » testing advanced the quantitative evaluat ion of the relationship between material heterogeneity and mechanical behavior. T he spatial distribution of compositional heterogeneity, anisotropic bedding patterns, and mechanical anisotropy were employed as inputs for brittle fracture simulations using a phase field model . Comparison of experimental and numerical simulations reveal ed that proper incorporation of additional material information, such as bedding layer thickness and other geometrical attributes of the microstructures, can yield improvements on the numerical prediction of the mesoscale fracture patterns and hence the macroscopic effective toughness. Overall, a comprehensive framework to evaluate the relationship between mechanical response and micro-lithofacial features can allow us to make more accurate prediction of reservoir performance by developing a multi - scale understanding of poromechanical response to coupled chemical and mechanical interactions for subsurface energy related activities.« less

Asymmetric Nanopore Electrode-Based Amplification for Electron Transfer Imaging in Live Cells.

PubMed

Ying, Yi-Lun; Hu, Yong-Xu; Gao, Rui; Yu, Ru-Jia; Gu, Zhen; Lee, Luke P; Long, Yi-Tao

2018-04-25

Capturing real-time electron transfer, enzyme activity, molecular dynamics, and biochemical messengers in living cells is essential for understanding the signaling pathways and cellular communications. However, there is no generalizable method for characterizing a broad range of redox-active species in a single living cell at the resolution of cellular compartments. Although nanoelectrodes have been applied in the intracellular detection of redox-active species, the fabrication of nanoelectrodes to maximize the signal-to-noise ratio of the probe remains challenging because of the stringent requirements of 3D fabrication. Here, we report an asymmetric nanopore electrode-based amplification mechanism for the real-time monitoring of NADH in a living cell. We used a two-step 3D fabrication process to develop a modified asymmetric nanopore electrode with a diameter down to 90 nm, which allowed for the detection of redox metabolism in living cells. Taking advantage of the asymmetric geometry, the above 90% potential drop at the two terminals of the nanopore electrode converts the faradaic current response into an easily distinguishable bubble-induced transient ionic current pattern. Therefore, the current signal was amplified by at least 3 orders of magnitude, which was dynamically linked to the presence of trace redox-active species. Compared to traditional wire electrodes, this wireless asymmetric nanopore electrode exhibits a high signal-to-noise ratio by increasing the current resolution from nanoamperes to picoamperes. The asymmetric nanopore electrode achieves the highly sensitive and selective probing of NADH concentrations as low as 1 pM. Moreover, it enables the real-time nanopore monitoring of the respiration chain (i.e., NADH) in a living cell and the evaluation of the effects of anticancer drugs in an MCF-7 cell. We believe that this integrated wireless asymmetric nanopore electrode provides promising building blocks for the future imaging of electron transfer dynamics in live cells.

Some properties of electrolyte solutions in nanoconfinement revealed by the measurement of transient filtration potential after pressure switch off.

PubMed

Yaroshchuk, Andriy E; Boiko, Yuriy P; Makovetskiy, Alexandre L

2005-08-16

We have demonstrated that with a composite nanoporous ceramic membrane in a batch membrane cell it is technically feasible to switch off the trans-membrane hydrostatic pressure difference within tens of milliseconds. That enabled us to resolve practically the whole time evolution of transient filtration potential. Measurements of the latter have been complemented by measurements of steady-state salt rejection by the composite membrane and by measurements of the streaming potential and hydraulic permeability of membrane supports available separately. A theory has been developed in terms of network thermodynamics for the electrical response of a bilayer membrane to a pressure perturbation. In combination with the results of salt rejection measurements, from the time transients of filtration potential we could determine the ion transport numbers within the nanoporous layer. Besides that, from the dependence of steady-state salt rejection on the trans-membrane volume flow, we have determined the diffusion permeability of and the salt reflection coefficient in the nanoporous layer. This has enabled us to estimate the contributions of Donnan and non-Donnan mechanisms to the rejection of ions by the nanoporous membrane used in this study. It has been unexpectedly found that the Donnan exclusion played only a secondary role. Our hypothesis is that the non-Donnan exclusion of ions from the nanopores might be caused by changes in water properties in nanoconfinement. Proceeding from the results of steady-state filtration experiments with the membrane and the support, we also concluded that the nanoporous layer was imperfection-free and had a quite narrow pore size distribution, which made it a suitable object for fundamental studies of ion transfer mechanisms in nanopores.

Asymmetric nanopore membranes: Single molecule detection and unique transport properties

NASA Astrophysics Data System (ADS)

Bishop, Gregory William

Biological systems rely on the transport properties of transmembrane channels. Such pores can display selective transport by allowing the passage of certain ions or molecules while rejecting others. Recent advances in nanoscale fabrication have allowed the production of synthetic analogs of such channels. Synthetic nanopores (pores with a limiting dimension of 1--100 nm) can be produced in a variety of materials by several different methods. In the Martin group, we have been exploring the track-etch method to produce asymmetric nanopores in thin films of polymeric or crystalline materials. Asymmetric nanopores are of particular interest due to their ability to serve as ion-current rectifiers. This means that when a membrane that contains such a pore or collection of pores is used to separate identical portions of electrolyte solution, the magnitude of the ionic current will depend not only on the magnitude of the applied potential (as expected) but also the polarity. Ion-current rectification is characterized by an asymmetric current--potential response. Here, the interesting transport properties of asymmetric nanopores (ion-current rectification and the related phenomenon of electroosmotic flow rectification) are explored. The effects of pore shape and pore density on these phenomena are investigated. Membranes that contain a single nanopore can serve as platforms for the single-molecule sensing technique known as resistive pulse sensing. The resistive-pulse sensing method is based on the Coulter principle. Thus, the selectivity of the technique is based largely upon size, making the analysis of mixtures by this method difficult in many cases. Here, the surface of a single nanopore membrane is modified with a molecular recognition agent in an attempt to obtain a more selective resistive-pulse sensor for a specific analyte.

Electric double-layer capacitors based on highly graphitized nanoporous carbons derived from ZIF-67.

PubMed

Torad, Nagy L; Salunkhe, Rahul R; Li, Yunqi; Hamoudi, Hicham; Imura, Masataka; Sakka, Yoshio; Hu, Chi-Chang; Yamauchi, Yusuke

2014-06-23

Nanoporous carbons (NPCs) have large specific surface areas, good electrical and thermal conductivity, and both chemical and mechanical stability, which facilitate their use in energy storage device applications. In the present study, highly graphitized NPCs are synthesized by one-step direct carbonization of cobalt-containing zeolitic imidazolate framework-67 (ZIF-67). After chemical etching, the deposited Co content can be completely removed to prepare pure NPCs with high specific surface area, large pore volume, and intrinsic electrical conductivity (high content of sp(2) -bonded carbons). A detailed electrochemical study is performed using cyclic voltammetry and galvanostatic charge-discharge measurements. Our NPC is very promising for efficient electrodes for high-performance supercapacitor applications. A maximum specific capacitance of 238 F g(-1) is observed at a scan rate of 20 mV s(-1) . This value is very high compared to previous works on carbon-based electric double layer capacitors. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanoporous Cu–Al–Co Alloys for Selective Furfural Hydrodeoxygenation to 2-Methylfuran

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hutchings, Gregory S.; Luc, Wesley; Lu, Qi

By finding new catalysts for selective and efficient conversion of biomass-derived products to industrially relevant chemicals and fuels, a transition from fossil fuel feedstocks may be achieved. Furfural (C 5H 4O 2) is a platform chemical which may be converted to multiple heterocyclic and ring-opening products, but to date there have been few catalysts which enable selective hydrodeoxygenation to 2-methylfuran (2-MF, C 5H 6O). Here, we present a self-supported nanoporous Cu–Al–Co ternary alloy catalyst with high furfural HDO activity toward 2-MF, achieving up to 66.0% selectivity and 98.2% overall conversion at 513 K with only a ~5 atomic % Comore » composition. Some further analysis over multiple temperature conditions and nominal Co concentrations was performed to examine optimal conditions and tune catalyst performance, and operando X-ray absorption spectroscopy experiments were conducted to elucidate the structure of the catalyst in the reaction environment.« less

Immobilization induced molecular compression of ionic liquid in ordered mesoporous matrix

NASA Astrophysics Data System (ADS)

Tripathi, Alok Kumar; Singh, Rajendra Kumar

2018-02-01

In this work, ionic liquid (IL) 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide ([EMIM][FSI]) has been immobilized into ordered mesoporous silica MCM-41 by a physical imbibition process. Transmission electron microscopy confirms the filling of mesopores of MCM-41. The effect of IL content in MCM-41 was probed in terms of thermal stability, chemical interactions, and dielectric properties. N2-sorption results indicate the compression of the IL in the nanopores of MCM-41, which contributes to an increase of the melting point probed by differential scanning calorimetry. The quantum chemical calculations confirmed that the ion-ion interaction in ion-pairs of IL were preferred over the hydrogen bonding interaction in the presence of SiO2 molecules, and these interactions probably compress the molecular size in the nanopores of MCM-41. Strong interactions between IL and porous MCM-41 were suggested as the mechanism of this immobilization, which was characterized by FTIR and dielectric spectroscopy.

Characterization of nanosecond pulse electrical field shock waves using imaging techniques

NASA Astrophysics Data System (ADS)

Mimun, L. Chris; Ibey, Bennett L.; Roth, Caleb C.; Barnes, Ronald A.; Sardar, Dhiraj K.; Beier, Hope T.

2015-03-01

Nanosecond pulsed electric fields (nsPEF) cause the formation of small pores, termed nanopores, in the membrane of cells. Current nanoporation models treat nsPEF exposure as a purely electromagnetic phenomenon, but recent publications showing pressure transients, ROS production, temperature gradients, and pH waves suggest the stimulus may be physically and chemically multifactorial causing elicitation of diverse biological conditions and stressors. Our research group's goal is to quantify the breadth and participation of these stressors generated during nsPEF exposure and determine their relative importance to the observed cellular response. In this paper, we used advanced imaging techniques to identify a possible source of nsPEF-induced acoustic shock waves. nsPEFs were delivered in an aqueous media via a pair of 125 μm tungsten electrodes separated by 100 μm, mirroring our previously published cellular exposure experiments. To visualize any pressure transients emanating from the electrodes or surrounding medium, we used the Schlieren imaging technique. Resulting images and measurements confirmed that mechanical pressure waves and electrode-based stresses are formed during nsPEF, resulting in a clearer understanding of the whole exposure dosimetry. This information will be used to better quantify the impact of nsPEF-induced acoustic shock waves on cells, and has provided further evidence of non-electrical-field induced exposures for elicitation of bioieffects.

Catalytic conversion in nanoporous materials: Concentration oscillations and spatial correlations due to inhibited transport and intermolecular interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia, Andres; Evans, James W.

2016-11-03

We show that steady-state catalytic conversion in nanoporous materials can occur in a quasi-counter-diffusion mode with the reactant (product) concentration strongly decaying (growing) into the pore, but also with oscillations in the total concentration. These oscillations reflect the response of the fluid to the transition from an extended to a confined environment near the pore opening. We focus on the regime of strongly inhibited transport in narrow pores corresponding to single-file diffusion. Here, limited penetration of the reactant into the pores and the associated low reaction yield is impacted by strong spatial correlations induced by both reaction (non-equilibrium correlations) andmore » also by intermolecular interactions (thermodynamic correlations). We develop a generalized hydrodynamic formulation to effectively describe inhibited transport accounting for the effect of these correlations, and incorporate this description of transport into appropriate reaction-diffusion equations. These equations accurately describe both shorter-range concentration oscillations near the pore opening and the longer-range mesoscale variation of concentration profiles in the pore (and thus also describe reaction yield). Success of the analytic theory is validated by comparison with a precise kinetic Monte Carlo simulation of an appropriate molecular-level stochastic reaction-diffusion model. As a result, this work elucidates unconventional chemical kinetics in interacting confined systems.« less

Nanocarbon-Coated Porous Anodic Alumina for Bionic Devices

PubMed Central

Aramesh, Morteza; Tong, Wei; Fox, Kate; Turnley, Ann; Seo, Dong Han; Prawer, Steven; Ostrikov, Kostya (Ken)

2015-01-01

A highly-stable and biocompatible nanoporous electrode is demonstrated herein. The electrode is based on a porous anodic alumina which is conformally coated with an ultra-thin layer of diamond-like carbon. The nanocarbon coating plays an essential role for the chemical stability and biocompatibility of the electrodes; thus, the coated electrodes are ideally suited for biomedical applications. The corrosion resistance of the proposed electrodes was tested under extreme chemical conditions, such as in boiling acidic/alkali environments. The nanostructured morphology and the surface chemistry of the electrodes were maintained after wet/dry chemical corrosion tests. The non-cytotoxicity of the electrodes was tested by standard toxicity tests using mouse fibroblasts and cortical neurons. Furthermore, the cell–electrode interaction of cortical neurons with nanocarbon coated nanoporous anodic alumina was studied in vitro. Cortical neurons were found to attach and spread to the nanocarbon coated electrodes without using additional biomolecules, whilst no cell attachment was observed on the surface of the bare anodic alumina. Neurite growth appeared to be sensitive to nanotopographical features of the electrodes. The proposed electrodes show a great promise for practical applications such as retinal prostheses and bionic implants in general. PMID:28793486

Phosphatase activity and its relationship with physical and chemical parameters during vermicomposting of filter cake and cattle manure.

PubMed

Busato, Jader Galba; Papa, Gabriella; Canellas, Luciano Pasqualoto; Adani, Fabrizio; de Oliveira, Aline Lima; Leão, Tairone Paiva

2016-03-15

Recycling of phosphorus (P) from organic residues (ORs) is important to develop environmentally friendly agriculture. The use of this P source depends on phosphatase enzymes, which can be affected by a chain of parameters during maturation of ORs. In this study the phosphatase activity levels throughout vermicomposting of filter cake (FC) and cattle manure (CM) were correlated with different physical and chemical parameters in an effort to increase the knowledge about recycling of P from ORs. FC presented higher total nitrogen content (TNC), total organic carbon (TOC), humic acid (HA) content, water-soluble P (WSP), phosphatase activities and nanopore volume than CM during vermicomposting. Decreases in TOC of CM resulted from carbohydrate mineralization, which was not observed for FC. CM showed increased hydrophobic index during vermicomposting while FC showed a slight decrease. Phosphatase activities correlated positively with TOC, pH and WSP and negatively with HA content for both vermicomposts. Nanopore volume was negatively correlated with phosphatase activities for FC but not for CM. No correlations between hydrophobicity and phosphatase activities were found for FC. Increased hydrophobicity throughout vermicomposting of CM could be partially associated with decreases in phosphatase levels. © 2015 Society of Chemical Industry.

Characterization of Pressure Transients Generated by Nanosecond Electrical Pulse (nsEP) Exposure

PubMed Central

Roth, Caleb C.; Barnes Jr., Ronald A.; Ibey, Bennett L.; Beier, Hope T.; Christopher Mimun, L.; Maswadi, Saher M.; Shadaram, Mehdi; Glickman, Randolph D.

2015-01-01

The mechanism(s) responsible for the breakdown (nanoporation) of cell plasma membranes after nanosecond pulse (nsEP) exposure remains poorly understood. Current theories focus exclusively on the electrical field, citing electrostriction, water dipole alignment and/or electrodeformation as the primary mechanisms for pore formation. However, the delivery of a high-voltage nsEP to cells by tungsten electrodes creates a multitude of biophysical phenomena, including electrohydraulic cavitation, electrochemical interactions, thermoelastic expansion, and others. To date, very limited research has investigated non-electric phenomena occurring during nsEP exposures and their potential effect on cell nanoporation. Of primary interest is the production of acoustic shock waves during nsEP exposure, as it is known that acoustic shock waves can cause membrane poration (sonoporation). Based on these observations, our group characterized the acoustic pressure transients generated by nsEP and determined if such transients played any role in nanoporation. In this paper, we show that nsEP exposures, equivalent to those used in cellular studies, are capable of generating high-frequency (2.5 MHz), high-intensity (>13 kPa) pressure transients. Using confocal microscopy to measure cell uptake of YO-PRO®-1 (indicator of nanoporation of the plasma membrane) and changing the electrode geometry, we determined that acoustic waves alone are not responsible for poration of the membrane. PMID:26450165

Nanopore sensing of individual transcription factors bound to DNA

PubMed Central

Squires, Allison; Atas, Evrim; Meller, Amit

2015-01-01

Transcription factor (TF)-DNA interactions are the primary control point in regulation of gene expression. Characterization of these interactions is essential for understanding genetic regulation of biological systems and developing novel therapies to treat cellular malfunctions. Solid-state nanopores are a highly versatile class of single-molecule sensors that can provide rich information about local properties of long charged biopolymers using the current blockage patterns generated during analyte translocation, and provide a novel platform for characterization of TF-DNA interactions. The DNA-binding domain of the TF Early Growth Response Protein 1 (EGR1), a prototypical zinc finger protein known as zif268, is used as a model system for this study. zif268 adopts two distinct bound conformations corresponding to specific and nonspecific binding, according to the local DNA sequence. Here we implement a solid-state nanopore platform for direct, label- and tether-free single-molecule detection of zif268 bound to DNA. We demonstrate detection of single zif268 TFs bound to DNA according to current blockage sublevels and duration of translocation through the nanopore. We further show that the nanopore can detect and discriminate both specific and nonspecific binding conformations of zif268 on DNA via the distinct current blockage patterns corresponding to each of these two known binding modes. PMID:26109509

Functional Nanopores: A Solid-state Concept for Artificial Reaction Compartments and Molecular Factories.

PubMed

Puebla-Hellmann, Gabriel; Mayor, Marcel; Lörtscher, Emanuel

2016-01-01

On the road towards the long-term goal of the NCCR Molecular Systems Engineering to create artificial molecular factories, we aim at introducing a compartmentalization strategy based on solid-state silicon technology targeting zeptoliter reaction volumes and simultaneous electrical contact to ensembles of well-oriented molecules. This approach allows the probing of molecular building blocks under a controlled environment prior to their use in a complex molecular factory. Furthermore, these ultra-sensitive electrical conductance measurements allow molecular responses to a variety of external triggers to be used as sensing and feedback mechanisms. So far, we demonstrate the proof-of-concept by electrically contacting self-assembled mono-layers of alkane-dithiols as an established test system. Here, the molecular films are laterally constrained by a circular dielectric confinement, forming a so-called 'nanopore'. Device yields above 85% are consistently achieved down to sub-50 nm nanopore diameters. This generic platform will be extended to create distributed, cascaded reactors with individually addressable reaction sites, including interconnecting micro-fluidic channels for electrochemical communication among nanopores and sensing sites for reaction control and feedback. In this scientific outlook, we will sketch how such a solid-state nanopore concept can be used to study various aspects of molecular compounds tailored for operation in a molecular factory.

Nanopore sensing of individual transcription factors bound to DNA

NASA Astrophysics Data System (ADS)

Squires, Allison; Atas, Evrim; Meller, Amit

2015-06-01

Transcription factor (TF)-DNA interactions are the primary control point in regulation of gene expression. Characterization of these interactions is essential for understanding genetic regulation of biological systems and developing novel therapies to treat cellular malfunctions. Solid-state nanopores are a highly versatile class of single-molecule sensors that can provide rich information about local properties of long charged biopolymers using the current blockage patterns generated during analyte translocation, and provide a novel platform for characterization of TF-DNA interactions. The DNA-binding domain of the TF Early Growth Response Protein 1 (EGR1), a prototypical zinc finger protein known as zif268, is used as a model system for this study. zif268 adopts two distinct bound conformations corresponding to specific and nonspecific binding, according to the local DNA sequence. Here we implement a solid-state nanopore platform for direct, label- and tether-free single-molecule detection of zif268 bound to DNA. We demonstrate detection of single zif268 TFs bound to DNA according to current blockage sublevels and duration of translocation through the nanopore. We further show that the nanopore can detect and discriminate both specific and nonspecific binding conformations of zif268 on DNA via the distinct current blockage patterns corresponding to each of these two known binding modes.

Osmylated DNA, a novel concept for sequencing DNA using nanopores

NASA Astrophysics Data System (ADS)

Kanavarioti, Anastassia

2015-03-01

Saenger sequencing has led the advances in molecular biology, while faster and cheaper next generation technologies are urgently needed. A newer approach exploits nanopores, natural or solid-state, set in an electrical field, and obtains base sequence information from current variations due to the passage of a ssDNA molecule through the pore. A hurdle in this approach is the fact that the four bases are chemically comparable to each other which leads to small differences in current obstruction. ‘Base calling’ becomes even more challenging because most nanopores sense a short sequence and not individual bases. Perhaps sequencing DNA via nanopores would be more manageable, if only the bases were two, and chemically very different from each other; a sequence of 1s and 0s comes to mind. Osmylated DNA comes close to such a sequence of 1s and 0s. Osmylation is the addition of osmium tetroxide bipyridine across the C5-C6 double bond of the pyrimidines. Osmylation adds almost 400% mass to the reactive base, creates a sterically and electronically notably different molecule, labeled 1, compared to the unreactive purines, labeled 0. If osmylated DNA were successfully sequenced, the result would be a sequence of osmylated pyrimidines (1), and purines (0), and not of the actual nucleobases. To solve this problem we studied the osmylation reaction with short oligos and with M13mp18, a long ssDNA, developed a UV-vis assay to measure extent of osmylation, and designed two protocols. Protocol A uses mild conditions and yields osmylated thymidines (1), while leaving the other three bases (0) practically intact. Protocol B uses harsher conditions and effectively osmylates both pyrimidines, but not the purines. Applying these two protocols also to the complementary of the target polynucleotide yields a total of four osmylated strands that collectively could define the actual base sequence of the target DNA.

Ultrafast and scalable laser liquid synthesis of tin oxide nanotubes and its application in lithium ion batteries

NASA Astrophysics Data System (ADS)

Liu, Zhikun; Cao, Zeyuan; Deng, Biwei; Wang, Yuefeng; Shao, Jiayi; Kumar, Prashant; Liu, C. Richard; Wei, Bingqing; Cheng, Gary J.

2014-05-01

Laser-induced photo-chemical synthesis of SnO2 nanotubes has been demonstrated by employing a nanoporous polycarbonate membrane as a template. The SnO2 nanotube diameter can be controlled by the nanoporous template while the nanotube length can be tuned by laser parameters and reaction duration. The microstructure characterization of the nanotubes indicates that they consist of mesoporous structures with sub 5 nm size nanocrystals connected by the twinning structure. The application of SnO2 nanotubes as an anode material in lithium ion batteries has also been explored, and they exhibited high capacity and excellent cyclic stability. The laser based emerging technique for scalable production of crystalline metal oxide nanotubes in a matter of seconds is remarkable. The compliance of the laser based technique with the existing technologies would lead to mass production of novel nanomaterials that would be suitable for several emerging applications.Laser-induced photo-chemical synthesis of SnO2 nanotubes has been demonstrated by employing a nanoporous polycarbonate membrane as a template. The SnO2 nanotube diameter can be controlled by the nanoporous template while the nanotube length can be tuned by laser parameters and reaction duration. The microstructure characterization of the nanotubes indicates that they consist of mesoporous structures with sub 5 nm size nanocrystals connected by the twinning structure. The application of SnO2 nanotubes as an anode material in lithium ion batteries has also been explored, and they exhibited high capacity and excellent cyclic stability. The laser based emerging technique for scalable production of crystalline metal oxide nanotubes in a matter of seconds is remarkable. The compliance of the laser based technique with the existing technologies would lead to mass production of novel nanomaterials that would be suitable for several emerging applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr06444a

The role of nanosecond electric pulse-induced mechanical stress in cellular nanoporation

NASA Astrophysics Data System (ADS)

Roth, Caleb C.

Background: Exposures of cells to very short (less than 1 microsecond) electric pulses in the megavolt/meter range have been shown to cause a multitude of effects, both physical and molecular in nature. Physically, nanosecond electrical pulse exposure can disrupt the plasma membrane, leading to a phenomenon known as nanoporation. Nanoporation is the production of nanometer sized holes (less than 2 nanometers in diameter) that can persist for up to fifteen minutes, allowing the flow of ions into and out of the cell. Nanoporation can lead to secondary physical effects, such as cellular swelling, shrinking and blebbing. Molecularly, nanosecond electrical pulses have been shown to activate signaling pathways, produce oxidative stress, stimulate hormone secretion and induce both apoptotic and necrotic death. The mechanism by which nanosecond electrical pulses cause molecular changes is unknown; however, it is thought the flow of ions, such as calcium, into the cell via nanopores, could be a major cause. The ability of nanosecond electrical pulses to cause membranes to become permeable and to induce apoptosis makes the technology a desirable modality for cancer research; however, the lack of understanding regarding the mechanisms by which nanosecond electrical pulses cause nanoporation impedes further development of this technology. This dissertation documents the genomic and proteomic responses of cells exposed to nanosecond electrical pulses and describes in detail the biophysical effects of these electrical pulses, including the demonstration for the first time of the generation of acoustic pressure transients capable of disrupting plasma membranes and possibly contributing to nanoporation. Methods: Jurkat, clone E6-1 (human lymphocytic cell line), U937 (human lymphocytic cell line), Chinese hamster ovarian cells and adult primary human dermal fibroblasts exposed to nanosecond electrical pulses were subjected to a variety of molecular assays, including flow cytometry, fluorescent confocal microscopy, microarray analysis and or real time polymerase chain reaction. To investigate the physical interaction(s) of the electrical pulse with the aqueous environment, optical techniques such as pump-probe imaging, schlieren imaging, and probe beam deflection were used. Finally, electrochemistry was employed to modify the electrical parameters of the exposures such that different biophysical phenomena could be detected. Results: Approximately 500 genes were selectively up-regulated in each of the assayed cells. Validation of the microarray data indicated genes such as the putative transforming gene of avian sarcoma virus 17, commonly known as jun proto-oncogene, and the Finkel--Biskis--Jinkins murine osteosarcoma viral oncogene homolog were significantly up-regulated in response to the exposure. Many of the genes selectively up-regulated in each cell type are biomarkers of mechanical stress. Proteomic analysis indicated proteins responsible for mitigation of reactive oxygen species were produced in response to nanosecond electrical pulse exposure. Analysis using the Probe Beam Deflection Technique identified the generation of an acoustic pressure transient emanating from the electrodes immediately after the application of the pulse. This acoustic pressure transient traveled at approximately 1500 meters per second, had a frequency bandwidth of 2.5 megahertz and was capable of delivering 13 kilopascals of pressure at 5 millimeters distance from the generating electrodes. Visual confirmation of the acoustic pressure transients was accomplished using pump-probe, schlieren and ultrasonic imaging techniques. Modification of the bathing media in which the cells were exposed indicated that acoustic pressure transient formation was directly dependent on the amount of electrical current induced by the exposure. Confocal microscopy revealed that, in the absence of the acoustic pressure transients, nanoporation, as detected by a green fluorescent carbocyanine nucleic acid stain, was greatly enhanced. Conclusions: We found several genes, some of which are mechanosensitive, were selectively up-regulated due to nanosecond electrical pulse exposure. The source of this apparent mechanical stress was likely the acoustic pressure transients generated by the nanosecond electrical pulse exposure interacting with the plasma membrane of exposed cells. Contrary to our original hypothesis that these acoustic pressure transients enhance nanoporation, it appears that the opposite is true. Acoustic pressure transients generated by nanosecond electrical pulses inhibit nanoporation (or at least are negatively correlated with nanopore formation). This finding is substantiated by other reports in the literature, which indicate shock waves produced by electrical exposures inhibit gene transfection. General Significance: This work provides strong evidence that cells exposed to nanosecond electrical pulses experience a mechanical stress which by some unknown mechanism inhibits nanoporation. The findings in this dissertation are not only poised to cause a paradigm shift in how researchers understand electrical pulses cause electropermeabilization, but also will help fill in a gap in the knowledge concerning this technology, thus enabling its further development as a potential cancer therapy.

Tuning ligament shape in dealloyed nanoporous tin and the impact of nanoscale morphology on its applications in Na-ion alloy battery anodes

NASA Astrophysics Data System (ADS)

Detsi, Eric; Petrissans, Xavier; Yan, Yan; Cook, John B.; Deng, Ziling; Liang, Yu-Lun; Dunn, Bruce; Tolbert, Sarah H.

2018-05-01

Control over the morphology of nanostructured materials is of primary importance in structure-property relationship studies. Although the size of ligaments and pores in dealloyed nanoporous metals can be controlled by thermal and/or (electro)chemical treatments, tuning the shape of those ligaments is much harder. In the present work, we use corroding media with different reactivity to effectively tailor the ligament shape in nanoporous tin (NP-Sn) during dealloying by free corrosion. NP-Sn architectures with nanowire and granular ligament shapes were made by controlling the pH of the corroding solution, and thus the rate of Sn oxidation relative to the etching rate of the sacrificial component. The standard nanowire structure was formed under acidic conditions where oxidation was slow, but a hierarchical granular structure was formed when fusion of the Sn nanocrystals was inhibited by surface oxidation. To demonstrate the advantages of this architectural control, these two materials systems were investigated as electrodes for Na-ion battery anodes. Similar initial Na storage capacities of ˜500 and 550 mAh/g were achieved in the nanowire and granular materials, respectively, but the cycle life of the two materials was quite different. NP-Sn with a granular ligament shape showed enhanced stability with a capacity retention of ˜55 % over 95 cycles at a specific current of 40 mA/g. By contrast, NP-Sn with a nanowire ligament shape showed very fast capacity fading within the first 10 cycles. This work thus demonstrates the dramatic impact of the nanoscale morphology on the electrochemical performance of nanoporous materials and highlights the need for both shape and size control in dealloyed nanoporous metals.

Nanostructures and radionuclide transport in clay formations (Invited)

NASA Astrophysics Data System (ADS)

Wang, Y.

2010-12-01

Nanostructures are widely present in geologic materials and are expected to directly affect the interactions of these materials with geologic fluids. The study of mineral-water interface chemistry as controlled by nanostructures is a necessary step to bridge the existing gap between the molecular level understanding of a geochemical process and the macro-scale laboratory and field observations. In this presentation, I will review the recent progresses in nanoscience and provide a perspective on how these progresses can potentially impact geochemical studies. My presentation will be focused the following areas: (1) the characterization of nanostructures in natural systems, (2) the study of water and chemical species in nanoconfinement, (3) the effects of nanopores on geochemical reaction and mass transfers, and (4) the use nanostructured materials for environmental remediation and cleanup. Specifically, I will demonstrate that the nanopore confinement can significantly modify geochemical reactions in porous geologic media. As the pore size is reduced to a few nanometers, the difference between surface acidity constants (pK2 - pK1) decreases, giving rise to a higher surface charge density on a nanopore surface than that on an unconfined mineral-water interface. The change in surface acidity constants results in a shift of ion sorption edges and enhances ion sorption on nanopore surfaces. This effect causes preferential enrichment of trace elements in nanopores and therefore directly impacts the bioavailability of these elements. The implication of these processes to radionuclide transport in clay formations will be discussed. This work was performed at Sandia National Laboratories, which is a multiprogram laboratory operated by Sandia Corporation, a Lockheed-Martin Company, for the DOE under contract DE-AC04-94AL8500.

Depolarized haze of nano-porous AAO film via porosity and aspect control

NASA Astrophysics Data System (ADS)

Tseng, Chun-Wei; Lin, Yung-Hsiang; Cheng, Chih-Hsien; Lin, Gong-Ru

2018-01-01

Multiple scattering induced haze and depolarization effects of nano-porous AAO films controlled by detuning the porosity and aspect ratio of the nano holes are investigated. The nano-porous AAO film with its porosity increasing from 12.6% to 19.3% enhances the scattering of the incident laser beam with its maximal scattering angle enlarged from 5° to 8° under TM-mode incidence and from 6° to 10° under TE-mode incidence. Because of multiple scattering within the porous holes of the AAO, the depolarization on the reflected beam by transferring its electric field from horizontal to the vertical such that the polarization ratio is degraded with a randomized haze. The porosity of AAO surface broadens from 12.6% to 19.3% when increasing the bias voltage from 40 to 60 V during the second-step of the electro-chemical anodization process, which essentially adjusts the polarization ratio under TM-mode and TE-mode incidences raise from 0.31 to 0.35 and from 0.32 to 0.48, respectively. The depolarized haze of the nano-porous AAO film is correlated with its porosity and aspect ratio controlled by the pore size and etched depth of the AAO. Under TM-mode incidence, the simulated polarization ratio increases from 0.35 to 0.38, which correlates well with experimental results. In contrast, the experiment result slightly deviates from the theoretical prediction as the TE-mode field interacts more surface area than the TM-mode field does. Such a nano-porous AAO exhibits tunable depolarized haze via the control porosity and aspect ratio, which is particularly suitable to serve as the catalytic buffer for synthesizing the hydrophobic and hazed solar energy converters.

Multimodal nanoporous silica nanoparticles functionalized with aminopropyl groups for improving loading and controlled release of doxorubicin hydrochloride.

PubMed

Wang, Xin; Li, Chang; Fan, Na; Li, Jing; He, Zhonggui; Sun, Jin

2017-09-01

The purpose of this study was to develop amino modified multimodal nanoporous silica nanoparticles (M-NSNs-NH 2 ) loaded with doxorubicin hydrochloride (DOX), intended to enhance the drug loading capacity and to achieve controlled release effect. M-NSNs were functionalized with aminopropyl groups through post-synthesis. The contribution of large pore sizes and surface chemical groups on DOX loading and release were systemically studied using transmission electron microscope (TEM), nitrogen adsorption/desorption measurement, Fourier transform infrared spectroscopy (FTIR), zeta potential analysis, X-ray photoelectron spectroscopy (XPS) and ultraviolet spectrophotometer (UV). The results demonstrated that the NSNs were functionalized with aminopropyl successfully and the DOX molecules were adsorbed inside the nanopores by the hydrogen bonding. The release performance indicated that DOX loaded M-NSNs significantly controlled DOX release, furthermore DOX loaded M-NSNs-NH 2 performed slower controlled release, which was mainly attributed to its stronger hydrogen bonding forces. As expected, we developed a novel carrier with high drug loading capacity and controlled release for DOX. Copyright © 2017 Elsevier B.V. All rights reserved.

Nanoporous Hybrid Electrolytes for High-Energy Batteries Based on Reactive Metal Anodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tu, Zhengyuan; Zachman, Michael J.; Choudhury, Snehashis

2017-01-06

Successful strategies for stabilizing electrodeposition of reactive metals, including lithium, sodium, and aluminum are a requirement for safe, high-energy electrochemical storage technologies that utilize these metals as anodes. Unstable deposition produces high-surface area dendritic structures at the anode/electrolyte interface, which causes premature cell failure by complex physical and chemical processes that have presented formidable barriers to progress. Here, it is reported that hybrid electrolytes created by infusing conventional liquid electrolytes into nanoporous membranes provide exceptional ability to stabilize Li. Electrochemical cells based on γ-Al2O3 ceramics with pore diameters below a cut-off value above 200 nm exhibit long-term stability even atmore » a current density of 3 mA cm-2. The effect is not limited to ceramics; similar large enhancements in stability are observed for polypropylene membranes with less monodisperse pores below 450 nm. These findings are critically assessed using theories for ion rectification and electrodeposition reactions in porous solids and show that the source of stable electrodeposition in nanoporous electrolytes is fundamental.« less

Morphology dependent field emission characteristics of ZnS/silicon nanoporous pillar array

NASA Astrophysics Data System (ADS)

Wang, Ling Li; Zhao, Cheng Zhou; Kang, Li Ping; Liu, De Wei; Zhao, Hui Chun; Hao, Shan Peng; Zhang, Yuan Kai; Chen, Zhen Ping; Li, Xin Jian

2016-10-01

Through depositing zinc sulphide (ZnS) nanoparticals on silicon nanoporous pillar array (Si-NPA) and crater-shaped silicon nanoporous pillar array (c-Si-NPA) by chemical bath deposition (CBD) method, ZnS/Si-NPA and c-ZnS/Si-NPA were prepared and the field emission (FE) properties of them were investigated. The turn-on electric fields of were 3.8 V/mm for ZnS/Si-NPA and 5.0 V/mm for c-ZnS/Si-NPA, respectively. The lower turn-on electric fields of ZnS/Si-NPA than that of c-ZnS/Si-NPA were attributed to the different electric distribution of the field emitters causing by the different surface morphology of the two samples, which was further demonstrated via the simulated results by finite element modeling. The FN curves for the ZnS/Si-NPA showed two-slope behavior. All the results indicate that the morphology play an important role in the FE properties and designing an appropriate top morphology for the emitter is a very efficient way to improve the FE performance.

Nanoporous Gallium Nitride Through Anisotropic Metal-Assisted Electroless Photochemical Wet Etching Technique

NASA Astrophysics Data System (ADS)

Perumal, R.; Hassan, Z.

2016-12-01

Nanoporous gallium nitride (GaN) has many potential applications in light-emitting diodes (LEDs), photovoltaics, templates and chemical sensors. This article reports the porosification of GaN through UV enhanced metal-assisted electroless photochemical wet etching technique using three different acid-based etchants and platinum served as catalyst for porosification. The etching process was conducted at room temperature for a duration of 90min. The morphological, structural, spectral and optical features of the developed porous GaN were studied with appropriate characterization techniques and the obtained results were presented. Field emission scanning electron micrographs exhibited the porosity nature along with excellent porous network of the etched samples. Structural studies confirmed the mono crystalline quality of the porous nanostructures. Raman spectral analyzes inferred the presenting phonon modes such as E2 (TO) and A1 (LO) in fabricated nanoporous structures. The resulted porous nanostructures hold the substantially enhanced photoluminescence intensity compared with the pristine GaN epitaxial film that is interesting and desirable for several advances in the applications of Nano-optoelectronic devices.

Electrically Conductive and Optically Active Porous Silicon Nanowires

PubMed Central

Qu, Yongquan; Liao, Lei; Li, Yujing; Zhang, Hua; Huang, Yu; Duan, Xiangfeng

2009-01-01

We report the synthesis of vertical silicon nanowire array through a two-step metal-assisted chemical etching of highly doped n-type silicon (100) wafers in a solution of hydrofluoric acid and hydrogen peroxide. The morphology of the as-grown silicon nanowires is tunable from solid nonporous nanowires, nonporous/nanoporous core/shell nanowires, and entirely nanoporous nanowires by controlling the hydrogen peroxide concentration in the etching solution. The porous silicon nanowires retain the single crystalline structure and crystallographic orientation of the starting silicon wafer, and are electrically conductive and optically active with visible photoluminescence. The combination of electronic and optical properties in the porous silicon nanowires may provide a platform for the novel optoelectronic devices for energy harvesting, conversion and biosensing. PMID:19807130

Expanding the functionality and applications of nanopore sensors

NASA Astrophysics Data System (ADS)

Venta, Kimberly E.

Nanopore sensors have developed into powerful tools for single-molecule studies since their inception two decades ago. Nanopore sensors function as nanoscale Coulter counters, by monitoring ionic current modulations as particles pass through a nanopore. While nanopore sensors can be used to study any nanoscale particle, their most notable application is as a low cost, fast alternative to current DNA sequencing technologies. In recent years, signifcant progress has been made toward the goal of nanopore-based DNA sequencing, which requires an ambitious combination of a low-noise and high-bandwidth nanopore measurement system and spatial resolution. In this dissertation, nanopore sensors in thin membranes are developed to improve dimensional resolution, and these membranes are used in parallel with a high-bandwidth amplfier. Using this nanopore sensor system, the signals of three DNA homopolymers are differentiated for the first time in solid-state nanopores. The nanopore noise is also reduced through the addition of a layer of SU8, a spin-on polymer, to the supporting chip structure. By increasing the temporal and spatial resolution of nanopore sensors, studies of shorter molecules are now possible. Nanopore sensors are beginning to be used for the study and characterization of nanoparticles. Nanoparticles have found many uses from biomedical imaging to next-generation solar cells. However, further insights into the formation and characterization of nanoparticles would aid in developing improved synthesis methods leading to more effective and customizable nanoparticles. This dissertation presents two methods of employing nanopore sensors to benet nanoparticle characterization and fabrication. Nanopores were used to study the formation of individual nanoparticles and serve as nanoparticle growth templates that could be exploited to create custom nanoparticle arrays. Additionally, nanopore sensors were used to characterize the surface charge density of anisotropic nanopores, which previously could not be reliably measured. Current nanopore sensor resolution levels have facilitated innovative research on nanoscale systems, including studies of DNA and nanoparticle characterization. Further nanopore system improvements will enable vastly improved DNA sequencing capabilities and open the door to additional nanopore sensing applications.

Computational modeling of ion transport through nanopores.

PubMed

Modi, Niraj; Winterhalter, Mathias; Kleinekathöfer, Ulrich

2012-10-21

Nanoscale pores are ubiquitous in biological systems while artificial nanopores are being fabricated for an increasing number of applications. Biological pores are responsible for the transport of various ions and substrates between the different compartments of biological systems separated by membranes while artificial pores are aimed at emulating such transport properties. As an experimental method, electrophysiology has proven to be an important nano-analytical tool for the study of substrate transport through nanopores utilizing ion current measurements as a probe for the detection. Independent of the pore type, i.e., biological or synthetic, and objective of the study, i.e., to model cellular processes of ion transport or electrophysiological experiments, it has become increasingly important to understand the dynamics of ions in nanoscale confinements. To this end, numerical simulations have established themselves as an indispensable tool to decipher ion transport processes through biological as well as artificial nanopores. This article provides an overview of different theoretical and computational methods to study ion transport in general and to calculate ion conductance in particular. Potential new improvements in the existing methods and their applications are highlighted wherever applicable. Moreover, representative examples are given describing the ion transport through biological and synthetic nanopores as well as the high selectivity of ion channels. Special emphasis is placed on the usage of molecular dynamics simulations which already have demonstrated their potential to unravel ion transport properties at an atomic level.

Impedimetric DNA biosensor based on a nanoporous alumina membrane for the detection of the specific oligonucleotide sequence of dengue virus.

PubMed

Deng, Jiajia; Toh, Chee-Seng

2013-06-17

A novel and integrated membrane sensing platform for DNA detection is developed based on an anodic aluminum oxide (AAO) membrane. Platinum electrodes (~50-100 nm thick) are coated directly on both sides of the alumina membrane to eliminate the solution resistance outside the nanopores. The electrochemical impedance technique is employed to monitor the impedance changes within the nanopores upon DNA binding. Pore resistance (Rp) linearly increases in response towards the increasing concentration of the target DNA in the range of 1 × 10⁻¹² to 1 × 10⁻⁶ M. Moreover, the biosensor selectively differentiates the complementary sequence from single base mismatched (MM-1) strands and non-complementary strands. This study reveals a simple, selective and sensitive method to fabricate a label-free DNA biosensor.

Fast fabrication of long TiO2 nanotube array with high photoelectrochemical property on flexible stainless steel.

PubMed

Tao, Jie; Wu, Tao; Gao, Peng

2012-03-01

Oriented highly ordered long TiO2 nanotube array films with nanopore structure and high photoelectrochemical property were fabricated on flexible stainless steel substrate (50 microm) by anodization treatment of titanium thin films in a short time. The samples were characterized by means of field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and photoelectrochemical methods, respectively. The results showed that Ti films deposited at the condition of 0.7 Pa Ar pressure and 96 W sputtering power at room temperature was uniform and dense with good homogeneity and high crystallinity. The voltage and the anodization time both played significant roles in the formation of TiO2 nanopore-nanotube array film. The optimal voltage was 60 V and the anodization time is less than 30 min by anodizing Ti films in ethylene glycerol containing 0.5% (w) NH4F and 3% (w) H2O. The growth rate of TiO2 nanotube array was as high as 340 nm/min. Moreover, the photocurrent-potential curves, photocurrent response curves and electrochemical impedance spectra results indicated that the TiO2 nanotube array film with the nanoporous structure exhibited a better photo-response ability and photoelectrochemical performance than the ordinary TiO2 nanotube array film. The reason is that the nanoporous structure on the surface of the nanotube array can separate the photo electron-hole pairs more efficiently and completely than the tubular structure.

High density group IV semiconductor nanowire arrays fabricated in nanoporous alumina templates

NASA Astrophysics Data System (ADS)

Redwing, Joan M.; Dilts, Sarah M.; Lew, Kok-Keong; Cranmer, Alexana E.; Mohney, Suzanne E.

2005-11-01

The fabrication of high density arrays of semiconductor nanowires is of interest for nanoscale electronics, chemical and biological sensing and energy conversion applications. We have investigated the synthesis, intentional doping and electrical characterization of Si and Ge nanowires grown by the vapor-liquid-solid (VLS) method in nanoporous alumina membranes. Nanoporous membranes provide a convenient platform for nanowire growth and processing, enabling control of wire diameter via pore size and the integration of contact metals for electrical testing. For VLS growth in nanoporous materials, reduced pressures and temperatures are required in order to promote the diffusion of reactants into the pore without premature decomposition on the membrane surface or pore walls. The effect of growth conditions on the growth rate of Si and Ge nanowires from SiH 4 and GeH 4 sources, respectively, was investigated and compared. In both cases, the measured activation energies for nanowire growth were substantially lower than activation energies typically reported for Si and Ge thin film deposition under similar growth conditions, suggesting that gold plays a catalytic role in the VLS growth process. Intentionally doped SiNW arrays were also prepared using trimethylboron (TMB) and phosphine (PH 3) as p-type and n-type dopant sources, respectively. Nanowire resistivities were calculated from plots of the array resistance as a function of nanowire length. A decrease in resistivity was observed for both n-type and p-type doped SiNW arrays compared to those grown without the addition of a dopant source.

Can ionophobic nanopores enhance the energy storage capacity of electric-double-layer capacitors containing nonaqueous electrolytes?

DOE PAGES

Lian, Cheng; Univ. of California, Riverside, CA; Liu, Honglai; ...

2016-08-22

The ionophobicity effect of nanoporous electrodes on the capacitance and the energy storage capacity of nonaqueous-electrolyte supercapacitors is studied by means of the classical density functional theory (DFT). It has been hypothesized that ionophobic nanopores may create obstacles in charging, but they store energy much more efficiently than ionophilic pores. In this paper, we find that, for both ionic liquids and organic electrolytes, an ionophobic pore exhibits a charging behavior different from that of an ionophilic pore, and that the capacitance–voltage curve changes from a bell shape to a two-hump camel shape when the pore ionophobicity increases. For electric-double-layer capacitorsmore » containing organic electrolytes, an increase in the ionophobicity of the nanopores leads to a higher capacity for energy storage. Without taking into account the effects of background screening, the DFT predicts that an ionophobic pore containing an ionic liquid does not enhance the supercapacitor performance within the practical voltage ranges. However, by using an effective dielectric constant to account for ion polarizability, the DFT predicts that, like an organic electrolyte, an ionophobic pore with an ionic liquid is also able to increase the energy stored when the electrode voltage is beyond a certain value. We find that the critical voltage for an enhanced capacitance in an ionic liquid is larger than that in an organic electrolyte. Finally, our theoretical predictions provide further understanding of how chemical modification of porous electrodes affects the performance of supercapacitors.« less

Room-temperature synthesis of nanoporous 1D microrods of graphitic carbon nitride (g-C3N4) with highly enhanced photocatalytic activity and stability.

PubMed

Pawar, Rajendra C; Kang, Suhee; Park, Jung Hyun; Kim, Jong-Ho; Ahn, Sunghoon; Lee, Caroline S

2016-08-08

A one-dimensional (1D) nanostructure having a porous network is an exceptional photocatalytic material to generate hydrogen (H2) and decontaminate wastewater using solar energy. In this report, we synthesized nanoporous 1D microrods of graphitic carbon nitride (g-C3N4) via a facile and template-free chemical approach at room temperature. The use of concentrated acids induced etching and lift-off because of strong oxidation and protonation. Compared with the bulk g-C3N4, the porous 1D microrod structure showed five times higher photocatalytic degradation performance toward methylene blue dye (MB) under visible light irradiation. The photocatalytic H2 evolution of the 1D nanostructure (34 μmol g(-1)) was almost 26 times higher than that of the bulk g-C3N4 structure (1.26 μmol g(-1)). Additionally, the photocurrent stability of this nanoporous 1D morphology over 24 h indicated remarkable photocorrosion resistance. The improved photocatalytic activities were attributed to prolonged carrier lifetime because of its quantum confinement effect, effective separation and transport of charge carriers, and increased number of active sites from interconnected nanopores throughout the microrods. The present 1D nanostructure would be highly suited for photocatalytic water purification as well as water splitting devices. Finally, this facile and room temperature strategy to fabricate the nanostructures is very cost-effective.

Room-temperature synthesis of nanoporous 1D microrods of graphitic carbon nitride (g-C3N4) with highly enhanced photocatalytic activity and stability

NASA Astrophysics Data System (ADS)

Pawar, Rajendra C.; Kang, Suhee; Park, Jung Hyun; Kim, Jong-Ho; Ahn, Sunghoon; Lee, Caroline S.

2016-08-01

A one-dimensional (1D) nanostructure having a porous network is an exceptional photocatalytic material to generate hydrogen (H2) and decontaminate wastewater using solar energy. In this report, we synthesized nanoporous 1D microrods of graphitic carbon nitride (g-C3N4) via a facile and template-free chemical approach at room temperature. The use of concentrated acids induced etching and lift-off because of strong oxidation and protonation. Compared with the bulk g-C3N4, the porous 1D microrod structure showed five times higher photocatalytic degradation performance toward methylene blue dye (MB) under visible light irradiation. The photocatalytic H2 evolution of the 1D nanostructure (34 μmol g-1) was almost 26 times higher than that of the bulk g-C3N4 structure (1.26 μmol g-1). Additionally, the photocurrent stability of this nanoporous 1D morphology over 24 h indicated remarkable photocorrosion resistance. The improved photocatalytic activities were attributed to prolonged carrier lifetime because of its quantum confinement effect, effective separation and transport of charge carriers, and increased number of active sites from interconnected nanopores throughout the microrods. The present 1D nanostructure would be highly suited for photocatalytic water purification as well as water splitting devices. Finally, this facile and room temperature strategy to fabricate the nanostructures is very cost-effective.

Room-temperature synthesis of nanoporous 1D microrods of graphitic carbon nitride (g-C3N4) with highly enhanced photocatalytic activity and stability

PubMed Central

Pawar, Rajendra C.; Kang, Suhee; Park, Jung Hyun; Kim, Jong-ho; Ahn, Sunghoon; Lee, Caroline S.

2016-01-01

A one-dimensional (1D) nanostructure having a porous network is an exceptional photocatalytic material to generate hydrogen (H2) and decontaminate wastewater using solar energy. In this report, we synthesized nanoporous 1D microrods of graphitic carbon nitride (g-C3N4) via a facile and template-free chemical approach at room temperature. The use of concentrated acids induced etching and lift-off because of strong oxidation and protonation. Compared with the bulk g-C3N4, the porous 1D microrod structure showed five times higher photocatalytic degradation performance toward methylene blue dye (MB) under visible light irradiation. The photocatalytic H2 evolution of the 1D nanostructure (34 μmol g−1) was almost 26 times higher than that of the bulk g-C3N4 structure (1.26 μmol g−1). Additionally, the photocurrent stability of this nanoporous 1D morphology over 24 h indicated remarkable photocorrosion resistance. The improved photocatalytic activities were attributed to prolonged carrier lifetime because of its quantum confinement effect, effective separation and transport of charge carriers, and increased number of active sites from interconnected nanopores throughout the microrods. The present 1D nanostructure would be highly suited for photocatalytic water purification as well as water splitting devices. Finally, this facile and room temperature strategy to fabricate the nanostructures is very cost-effective. PMID:27498979

Synthesis of Three-Dimensional Nanoporous Li-Rich Layered Cathode Oxides for High Volumetric and Power Energy Density Lithium-Ion Batteries.

PubMed

Qiu, Bao; Yin, Chong; Xia, Yonggao; Liu, Zhaoping

2017-02-01

As rechargeable Li-ion batteries have expanded their applications into on-board energy storage for electric vehicles, the energy and power must be increased to meet the new demands. Li-rich layered oxides are one of the most promising candidate materials; however, it is very difficult to make them compatible with high volumetric energy density and power density. Here, we develop an innovative approach to synthesize three-dimensional (3D) nanoporous Li-rich layered oxides Li[Li 0.144 Ni 0.136 Co 0.136 Mn 0.544 ]O 2 , directly occurring at deep chemical delithiation with carbon dioxide. It is found that the as-prepared material presents a micrometer-sized spherical structure that is typically composed of interconnected nanosized subunits with narrow distributed pores at 3.6 nm. As a result, this unique 3D micro-/nanostructure not only has a high tap density over 2.20 g cm -3 but also exhibits excellent rate capability (197.6 mA h g -1 at 1250 mA g -1 ) as an electrode. The excellent electrochemical performance is ascribed to the unique nanoporous micro-nanostructures, which facilitates the Li + diffusion and enhances the structural stability of the Li-rich layered cathode materials. Our work offers a comprehensive designing strategy to construct 3D nanoporous Li-rich layered oxides for both high volumetric energy density and power density in Li-ion batteries.

The Role of Computer Simulation in Nanoporous Metals—A Review

PubMed Central

Xia, Re; Wu, Run Ni; Liu, Yi Lun; Sun, Xiao Yu

2015-01-01

Nanoporous metals (NPMs) have proven to be all-round candidates in versatile and diverse applications. In this decade, interest has grown in the fabrication, characterization and applications of these intriguing materials. Most existing reviews focus on the experimental and theoretical works rather than the numerical simulation. Actually, with numerous experiments and theory analysis, studies based on computer simulation, which may model complex microstructure in more realistic ways, play a key role in understanding and predicting the behaviors of NPMs. In this review, we present a comprehensive overview of the computer simulations of NPMs, which are prepared through chemical dealloying. Firstly, we summarize the various simulation approaches to preparation, processing, and the basic physical and chemical properties of NPMs. In this part, the emphasis is attached to works involving dealloying, coarsening and mechanical properties. Then, we conclude with the latest progress as well as the future challenges in simulation studies. We believe that highlighting the importance of simulations will help to better understand the properties of novel materials and help with new scientific research on these materials. PMID:28793491

Facile method for modulating the profiles and periods of self-ordered three-dimensional alumina taper-nanopores.

PubMed

Li, Juan; Li, Congshan; Chen, Cheng; Hao, Qingli; Wang, Zhijia; Zhu, Jie; Gao, Xuefeng

2012-10-24

We report a facile nanofabrication method, one-step hard anodizing and etching peeling (OS-HA-EP) of aluminum foils followed by multistep mild anodizing and etching pore-widening (MS-MA-EW), for the controllable tailoring of hexagonally packed three-dimensional alumina taper-nanopores. Their profiles can be precisely tailored by the synergistic control of anodizing time, etching time and cyclic times at the MS-MA-EW stage, exemplified by linear cones, whorl-embedded cones, funnels, pencils, parabolas, and trumpets. Meantime, their periods can also be modulated in the range of 70-370 nm by choosing matched anodizing electrolytes (e.g., H(2)C(2)O(4), H(2)SO(4), H(2)C(2)O(4)-H(2)SO(4), and H(2)C(2)O(4)-C(2)H(5)OH mixture) and anodizing voltages at the OS-HA-EP stage. We also demonstrated that the long-range ordering of nanopits and the peak voltage of stable self-ordered HA, which are unachievable in a single H(2)C(2)O(4) electrolyte system, can be effectively tuned by simply adding tiny quantity of H(2)SO(4) and C(2)H(5)OH to keep an appropriate HA current density, respectively. This method of using the combination of simple pure chemical nanofabrication technologies is very facile and efficient in realizing the controllable tailoring of large-area alumina membranes containing self-ordered taper-nanopores. Our work opens a door for exploring the novel physical and chemical properties of different materials of nanotaper arrays.

Nanoporous carbon materials with enhanced supercapacitance performance and non-aromatic chemical sensing with C1/C2 alcohol discrimination

NASA Astrophysics Data System (ADS)

Shrestha, Lok Kumar; Adhikari, Laxmi; Shrestha, Rekha Goswami; Adhikari, Mandira Pradhananga; Adhikari, Rina; Hill, Jonathan P.; Pradhananga, Raja Ram; Ariga, Katsuhiko

2016-01-01

We have investigated the textural properties, electrochemical supercapacitances and vapor sensing performances of bamboo-derived nanoporous carbon materials (NCM). Bamboo, an abundant natural biomaterial, was chemically activated with phosphoric acid at 400 °C and the effect of impregnation ratio of phosphoric acid on the textural properties and electrochemical performances was systematically investigated. Fourier transform-infrared (FTIR) spectroscopy confirmed the presence of various oxygen-containing surface functional groups (i.e. carboxyl, carboxylate, carbonyl and phenolic groups) in NCM. The prepared NCM are amorphous in nature and contain hierarchical micropores and mesopores. Surface areas and pore volumes were found in the range 218-1431 m2 g-1 and 0.26-1.26 cm3 g-1, respectively, and could be controlled by adjusting the impregnation ratio of phosphoric acid and bamboo cane powder. NCM exhibited electrical double-layer supercapacitor behavior giving a high specific capacitance of c.256 F g-1 at a scan rate of 5 mV s-1 together with high cyclic stability with capacitance retention of about 92.6% after 1000 cycles. Furthermore, NCM exhibited excellent vapor sensing performance with high sensitivity for non-aromatic chemicals such as acetic acid. The system would be useful to discriminate C1 and C2 alcohol (methanol and ethanol).

Influence of Nanopore Shapes on Thermal Conductivity of Two-Dimensional Nanoporous Material.

PubMed

Huang, Cong-Liang; Huang, Zun; Lin, Zi-Zhen; Feng, Yan-Hui; Zhang, Xin-Xin; Wang, Ge

2016-12-01

The influence of nanopore shapes on the electronic thermal conductivity (ETC) was studied in this paper. It turns out that with same porosity, the ETC will be quite different for different nanopore shapes, caused by the different channel width for different nanopore shapes. With same channel width, the influence of different nanopore shapes can be approximately omitted if the nanopore is small enough (smaller than 0.5 times EMFP in this paper). The ETC anisotropy was discovered for triangle nanopores at a large porosity with a large nanopore size, while there is a similar ETC for small pore size. It confirmed that the structure difference for small pore size may not be seen by electrons in their moving.

Nanoceramics for blood-borne virus removal.

PubMed

Zhao, Yufeng; Sugiyama, Sadahiro; Miller, Thomas; Miao, Xigeng

2008-05-01

The development of nanoscience and nanotechnology in the field of ceramics has brought new opportunities for the development of virus-removal techniques. A number of nanoceramics, including nanostructured alumina, titania and zirconia, have been introduced for the applications in virus removal or separation. Filtration or adsorption of viruses, and thus the removal of viruses through nanoceramics, such as nanoporous/mesoporous ceramic membranes, ceramic nanofibers and ceramic nanoparticles, will make it possible to produce an efficient system for virus removal from blood and one with excellent chemical/thermal stability. Currently, nanoceramic membranes and filters based on sol-gel alumina membranes and NanoCeram nanofiber filters have been commercialized and applied to remove viruses from the blood. Nevertheless, filtration using nanoporous filters is limited to the removal of only free viruses in the bloodstream.

Synthesis of single-crystal-like nanoporous carbon membranes and their application in overall water splitting

PubMed Central

Wang, Hong; Min, Shixiong; Ma, Chun; Liu, Zhixiong; Zhang, Weiyi; Wang, Qiang; Li, Debao; Li, Yangyang; Turner, Stuart; Han, Yu; Zhu, Haibo; Abou-hamad, Edy; Hedhili, Mohamed Nejib; Pan, Jun; Yu, Weili; Huang, Kuo-Wei; Li, Lain-Jong; Yuan, Jiayin; Antonietti, Markus; Wu, Tom

2017-01-01

Nanoporous graphitic carbon membranes with defined chemical composition and pore architecture are novel nanomaterials that are actively pursued. Compared with easy-to-make porous carbon powders that dominate the porous carbon research and applications in energy generation/conversion and environmental remediation, porous carbon membranes are synthetically more challenging though rather appealing from an application perspective due to their structural integrity, interconnectivity and purity. Here we report a simple bottom–up approach to fabricate large-size, freestanding and porous carbon membranes that feature an unusual single-crystal-like graphitic order and hierarchical pore architecture plus favourable nitrogen doping. When loaded with cobalt nanoparticles, such carbon membranes serve as high-performance carbon-based non-noble metal electrocatalyst for overall water splitting. PMID:28051082

Nanoporous aerogel as a bacteria repelling hygienic material for healthcare environment

NASA Astrophysics Data System (ADS)

Oh, Jun Kyun; Kohli, Nandita; Zhang, Yuanzhong; Min, Younjin; Jayaraman, Arul; Cisneros-Zevallos, Luis; Akbulut, Mustafa

2016-02-01

Healthcare-associated infections (HAIs) caused by pathogenic bacteria are a worldwide problem and responsible for numerous cases of morbidity and mortality. Exogenous cross-contamination is one of the main mechanisms contributing to such infections. This work investigates the potential of hydrophobically modified nanoporous silica aerogel as an antiadhesive hygienic material that can inhibit exogenous bacterial contamination. Nanoporous silica aerogels were synthesized via sol-gel polymerization of tetraethyl orthosilicate and hydrophobized using trimethylsilyl chloride. Bacterial adhesion characteristics were evaluated via dip-inoculation in suspensions of Gram-negative Escherichia coli O157:H7 and Gram-positive Staphylococcus aureus. The attachment of E. coli O157:H7 and S. aureus to hydrophobic nanoporous silica aerogel (HNSA) was found to be significantly lower than that to hydrophilic and hydrophobic nonporous silica materials: 99.91% (E. coli O157:H7) and 99.93% (S. aureus) reduction in comparison to hydrophilic nonporous silica, and 82.95% (E. coli O157:H7) and 84.90% (S. aureus) reduction in comparison to hydrophobic nonporous silica. These results suggest that the use of HNSA as surfaces that come into contact with bacterial pathogens in the healthcare environment can improve bacterial hygiene, and therefore may reduce the rate of HAIs.

Nanoporous aerogel as a bacteria repelling hygienic material for healthcare environment.

PubMed

Oh, Jun Kyun; Kohli, Nandita; Zhang, Yuanzhong; Min, Younjin; Jayaraman, Arul; Cisneros-Zevallos, Luis; Akbulut, Mustafa

2016-02-26

Healthcare-associated infections (HAIs) caused by pathogenic bacteria are a worldwide problem and responsible for numerous cases of morbidity and mortality. Exogenous cross-contamination is one of the main mechanisms contributing to such infections. This work investigates the potential of hydrophobically modified nanoporous silica aerogel as an antiadhesive hygienic material that can inhibit exogenous bacterial contamination. Nanoporous silica aerogels were synthesized via sol-gel polymerization of tetraethyl orthosilicate and hydrophobized using trimethylsilyl chloride. Bacterial adhesion characteristics were evaluated via dip-inoculation in suspensions of Gram-negative Escherichia coli O157:H7 and Gram-positive Staphylococcus aureus. The attachment of E. coli O157:H7 and S. aureus to hydrophobic nanoporous silica aerogel (HNSA) was found to be significantly lower than that to hydrophilic and hydrophobic nonporous silica materials: 99.91% (E. coli O157:H7) and 99.93% (S. aureus) reduction in comparison to hydrophilic nonporous silica, and 82.95% (E. coli O157:H7) and 84.90% (S. aureus) reduction in comparison to hydrophobic nonporous silica. These results suggest that the use of HNSA as surfaces that come into contact with bacterial pathogens in the healthcare environment can improve bacterial hygiene, and therefore may reduce the rate of HAIs.

Nanoporous Carbons: Looking Beyond Their Perception as Adsorbents, Catalyst Supports and Supercapacitors.

PubMed

Bandosz, Teresa J

2016-02-01

The discovery of carbon nanoforms, and especially graphene, has opened up new directions of science and technology. Many applications are based on the unique properties of graphene, such as its high electrical and thermal conductivity, strength, flexibility, photoactivity and transparency. Inspired by the emerging graphene science, we directed our efforts to the exploration of new applications of nanoporous (microporous) carbons. Their matrix is built of distorted graphene layers, between which pores with sizes ranging from a fraction of a nanometer to hundreds of nanometers exist. This is a very unique feature of nanoporous carbons resulting in their developed surface areas. Moreover, there are vast possibilities to modify the surface chemistry of carbons and thus their surface properties. Even though the traditional applications of porous carbons focus mainly on adsorption and separation, we decided to explore them as photocatalysts, oxygen reduction catalysts and sensors. Related to their visible-light activity, their possible application in solar energy harvesting is also indicated. This Personal Account presents our paths leading to the exploration of these directions, describing the results collected and difficulties encountered, along with the challenges remaining to be addressed. © 2015 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Protein-releasing conductive anodized alumina membranes for nerve-interface materials.

PubMed

Altuntas, Sevde; Buyukserin, Fatih; Haider, Ali; Altinok, Buket; Biyikli, Necmi; Aslim, Belma

2016-10-01

Nanoporous anodized alumina membranes (AAMs) have numerous biomedical applications spanning from biosensors to controlled drug delivery and implant coatings. Although the use of AAM as an alternative bone implant surface has been successful, its potential as a neural implant coating remains unclear. Here, we introduce conductive and nerve growth factor-releasing AAM substrates that not only provide the native nanoporous morphology for cell adhesion, but also induce neural differentiation. We recently reported the fabrication of such conductive membranes by coating AAMs with a thin C layer. In this study, we investigated the influence of electrical stimulus, surface topography, and chemistry on cell adhesion, neurite extension, and density by using PC 12 pheochromocytoma cells in a custom-made glass microwell setup. The conductive AAMs showed enhanced neurite extension and generation with the electrical stimulus, but cell adhesion on these substrates was poorer compared to the naked AAMs. The latter nanoporous material presents chemical and topographical features for superior neuronal cell adhesion, but, more importantly, when loaded with nerve growth factor, it can provide neurite extension similar to an electrically stimulated CAAM counterpart. Copyright © 2016 Elsevier B.V. All rights reserved.

Cavitation and pore blocking in nanoporous glasses.

PubMed

Reichenbach, C; Kalies, G; Enke, D; Klank, D

2011-09-06

In gas adsorption studies, porous glasses are frequently referred to as model materials for highly disordered mesopore systems. Numerous works suggest that an accurate interpretation of physisorption isotherms requires a complete understanding of network effects upon adsorption and desorption, respectively. The present article deals with nitrogen and argon adsorption at different temperatures (77 and 87 K) performed on a series of novel nanoporous glasses (NPG) with different mean pore widths. NPG samples contain smaller mesopores and significantly higher microporosity than porous Vycor glass or controlled pore glass. Since the mean pore width of NPG can be tuned sensitively, the evolution of adsorption characteristics with respect to a broadening pore network can be investigated starting from the narrowest nanopore width. With an increasing mean pore width, a H2-type hysteresis develops gradually which finally transforms into a H1-type. In this connection, a transition from a cavitation-induced desorption toward desorption controlled by pore blocking can be observed. Furthermore, we find concrete hints for a pore size dependence of the relative pressure of cavitation in highly disordered pore systems. By comparing nitrogen and argon adsorption, a comprehensive insight into adsorption mechanisms in novel disordered materials is provided. © 2011 American Chemical Society

Efficient biocatalyst by encapsulating lipase into nanoporous gold

PubMed Central

2013-01-01

Lipases are one of the most important biocatalysts for biotechnological applications. Immobilization is an efficient method to increase the stability and reusability of lipases. In this study, nanoporous gold (NPG), a new kind of nanoporous material with tunable porosity and excellent biocompatibility, was employed as an effective support for lipase immobilization. The pore size of NPG and adsorption time played key roles in the construction of lipase-NPG biocomposites. The morphology and composition of NPG before and after lipase loading are verified using a scanning electron microscope, equipped with an energy-dispersive X-ray spectrometer. The resulting lipase-NPG biocomposites exhibited excellent catalytic activity and remarkable reusability. The catalytic activity of the lipase-NPG biocomposite with a pore size of 35 nm had no decrease after ten recycles. Besides, the lipase-NPG biocomposite exhibited high catalytic activity in a broader pH range and higher temperature than that of free lipase. In addition, the leaching of lipase from NPG could be prevented by matching the protein’s diameter and pore size. Thus, the encapsulation of enzymes within NPG is quite useful for establishing new functions and will have wide applications for different chemical processes. PMID:23601503

Multiple Approaches to Characterizing Nano-Pore Structure of Barnett Shale

NASA Astrophysics Data System (ADS)

Hu, Q.; Gao, Z.; Ewing, R. P.; Dultz, S.; Kaufmann, J.; Hamamoto, S.; Webber, B.; Ding, M.

2013-12-01

Microscopic characteristics of porous media - pore shape, pore-size distribution, and pore connectivity - control fluid flow and mass transport. This presentation discusses various approaches to investigating nano-pore structure of Barnett shale, with its implications in gas production behavior. The innovative approaches include imbibition, tracer diffusion, edge-accessible porosity, porosimetry (mercury intrusion porosimetry, nitrogen and water vapor sorption isotherms, and nuclear magnetic resonance cyroporometry), and imaging (Wood's metal impregnation followed with laser ablation-inductively coupled plasma-mass spectrometry, focused ion beam/scanning electron microscopy, and small angle neutron scattering). Results show that the shale pores are predominantly in the nm size range, with measured median pore-throat diameters about 5 nm. But small pore size is not the major contributor to low gas recovery; rather, the low mass diffusivity appears to be caused by low pore connectivity of Barnett shale. Chemical diffusion in sparsely-connected pore spaces is not well described by classical Fickian behavior; anomalous behavior is suggested by percolation theory, and confirmed by results of imbibition and diffusion tests. Our evolving complementary approaches, with their several advantages and disadvantages, provide a rich toolbox for tackling the nano-pore structure characteristics of shales and other natural rocks.

Dramatic pressure-sensitive ion conduction in conical nanopores.

PubMed

Jubin, Laetitia; Poggioli, Anthony; Siria, Alessandro; Bocquet, Lydéric

2018-04-17

Ion transporters in Nature exhibit a wealth of complex transport properties such as voltage gating, activation, and mechanosensitive behavior. When combined, such processes result in advanced ionic machines achieving active ion transport, high selectivity, or signal processing. On the artificial side, there has been much recent progress in the design and study of transport in ionic channels, but mimicking the advanced functionalities of ion transporters remains as yet out of reach. A prerequisite is the development of ionic responses sensitive to external stimuli. In the present work, we report a counterintuitive and highly nonlinear coupling between electric and pressure-driven transport in a conical nanopore, manifesting as a strong pressure dependence of the ionic conductance. This result is at odds with standard linear response theory and is akin to a mechanical transistor functionality. We fully rationalize this behavior on the basis of the coupled electrohydrodynamics in the conical pore by extending the Poisson-Nernst-Planck-Stokes framework. The model is shown to capture the subtle mechanical balance occurring within an extended spatially charged zone in the nanopore. The pronounced sensitivity to mechanical forcing offers leads in tuning ion transport by mechanical stimuli. The results presented here provide a promising avenue for the design of tailored membrane functionalities.

Microfluidic multiplexing of solid-state nanopores

NASA Astrophysics Data System (ADS)

Jain, Tarun; Rasera, Benjamin C.; Guerrero, Ricardo Jose S.; Lim, Jong-Min; Karnik, Rohit

2017-12-01

Although solid-state nanopores enable electronic analysis of many clinically and biologically relevant molecular structures, there are few existing device architectures that enable high-throughput measurement of solid-state nanopores. Herein, we report a method for microfluidic integration of multiple solid-state nanopores at a high density of one nanopore per (35 µm2). By configuring microfluidic devices with microfluidic valves, the nanopores can be rinsed from a single fluid input while retaining compatibility for multichannel electrical measurements. The microfluidic valves serve the dual purpose of fluidic switching and electric switching, enabling serial multiplexing of the eight nanopores with a single pair of electrodes. Furthermore, the device architecture exhibits low noise and is compatible with electroporation-based in situ nanopore fabrication, providing a scalable platform for automated electronic measurement of a large number of integrated solid-state nanopores.

Threading DNA through nanopores for biosensing applications

NASA Astrophysics Data System (ADS)

Fyta, Maria

2015-07-01

This review outlines the recent achievements in the field of nanopore research. Nanopores are typically used in single-molecule experiments and are believed to have a high potential to realize an ultra-fast and very cheap genome sequencer. Here, the various types of nanopore materials, ranging from biological to 2D nanopores are discussed together with their advantages and disadvantages. These nanopores can utilize different protocols to read out the DNA nucleobases. Although, the first nanopore devices have reached the market, many still have issues which do not allow a full realization of a nanopore sequencer able to sequence the human genome in about a day. Ways to control the DNA, its dynamics and speed as the biomolecule translocates the nanopore in order to increase the signal-to-noise ratio in the reading-out process are examined in this review. Finally, the advantages, as well as the drawbacks in distinguishing the DNA nucleotides, i.e., the genetic information, are presented in view of their importance in the field of nanopore sequencing.

Hybrid micro/nanostructural surface offering improved stress distribution and enhanced osseointegration properties of the biomedical titanium implant.

PubMed

Hou, Ping-Jen; Ou, Keng-Liang; Wang, Chin-Chieh; Huang, Chiung-Fang; Ruslin, Muhammad; Sugiatno, Erwan; Yang, Tzu-Sen; Chou, Hsin-Hua

2018-03-01

The aim of the present study was to investigate the surface characteristic, biomechanical behavior, hemocompatibility, bone tissue response and osseointegration of the optimal micro-arc oxidation surface-treated titanium (MST-Ti) dental implant. The surface characteristic, biomechanical behavior and hemocompatibility of the MST-Ti dental implant were performed using scanning electron microscope, finite element method, blood dripping and immersion tests. The mini-pig model was utilized to evaluate the bone tissue response and osseointegration of the MST-Ti dental implant in vivo. Data were analyzed by analysis of variance using the Student's t-test (P ≤ 0.05). The hybrid volcano-like micro/nanoporous structure was formed on the surface of the MST-Ti dental implant. The hybrid volcano-like micro/nanoporous surface played an important role to improve the stress transfer between fixture, cortical bone and cancellous bone for the MST-Ti dental implant. Moreover, the MST-Ti implant was considered to have the outstanding hemocompatibility. In vivo testing results showed that the bone-to-implant contact (BIC) ratio significantly altered as the implant with micro/nanoporous surface. After 12 weeks of implantation, the MST-Ti dental implant group exhibited significantly higher BIC ratio than the untreated dental implant group. In addition, the MST-Ti dental implant group also presented an enhancing osseointegration, particularly in the early stages of bone healing. It can be concluded that the micro-arc oxidation approach induced the formation of micro/nanoporous surface is a promising and reliable alternative surface modification for Ti dental implant applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Nanoporous TiO2 and WO3 films by anodization of titanium and tungsten substrates: influence of process variables on morphology and photoelectrochemical response.

PubMed

de Tacconi, N R; Chenthamarakshan, C R; Yogeeswaran, G; Watcharenwong, A; de Zoysa, R S; Basit, N A; Rajeshwar, K

2006-12-21

The photoelectrochemical response of nanoporous films, obtained by anodization of Ti and W substrates in a variety of corrosive media and at preselected voltages in the range from 10 to 60 V, was studied. The as-deposited films were subjected to thermal anneal and characterized by scanning electron microscopy and X-ray diffraction. Along with the anodization media developed by previous authors, the effect of poly(ethylene glycol) (PEG 400) or D-mannitol as a modifier to the NH4F electrolyte and glycerol addition to the oxalic acid electrolyte was studied for TiO2 and WO3, respectively. In general, intermediate anodization voltages and film growth times yielded excellent-quality photoelectrochemical response for both TiO2 and WO3 as assessed by linear-sweep photovoltammetry and photoaction spectra. The photooxidation of water and formate species was used as reaction probes to assess the photoresponse quality of the nanoporous oxide semiconductor films. In the presence of formate as an electron donor, the incident photon to electron conversion efficiency (IPCE) ranged from approximately 130% to approximately 200% for both TiO2 and WO3 depending on the film preparation protocol. The best photoactive films were obtained from poly(ethylene glycol) (PEG 400) containing NH4F for TiO2 and from aqueous NaF for WO3.

Nanopore thin film enabled optical platform for drug loading and release.

PubMed

Song, Chao; Che, Xiangchen; Que, Long

2017-08-07

In this paper, a drug loading and release device fabricated using nanopore thin film and layer-by-layer (LbL) nanoassembly is reported. The nanopore thin film is a layer of anodic aluminum oxide (AAO), consisting of honeycomb-shape nanopores. Using the LbL nanoassembly process, the drug, using gentamicin sulfate (GS) as the model, can be loaded into the nanopores and the stacked layers on the nanopore thin film surface. The drug release from the device is achieved by immersing it into flowing DI water. Both the loading and release processes can be monitored optically. The effect of the nanopore size/volume on drug loading and release has also been evaluated. Further, the neuron cells have been cultured and can grow normally on the nanopore thin film, verifying its bio-compatibility. The successful fabrication of nanopore thin film device on silicon membrane render it as a potential implantable controlled drug release device.

Ion transport in a pH-regulated nanopore.

PubMed

Yeh, Li-Hsien; Zhang, Mingkan; Qian, Shizhi

2013-08-06

Fundamental understanding of ion transport phenomena in nanopores is crucial for designing the next-generation nanofluidic devices. Due to surface reactions of dissociable functional groups on the nanopore wall, the surface charge density highly depends upon the proton concentration on the nanopore wall, which in turn affects the electrokinetic transport of ions, fluid, and particles within the nanopore. Electrokinetic ion transport in a pH-regulated nanopore, taking into account both multiple ionic species and charge regulation on the nanopore wall, is theoretically investigated for the first time. The model is verified by the experimental data of nanopore conductance available in the literature. The results demonstrate that the spatial distribution of the surface charge density at the nanopore wall and the resulting ion transport phenomena, such as ion concentration polarization (ICP), ion selectivity, and conductance, are significantly affected by the background solution properties, such as the pH and salt concentration.

Single Molecule Sensing by Nanopores and Nanopore Devices

PubMed Central

Gu, Li-Qun; Shim, Ji Wook

2010-01-01

Molecular-scale pore structures, called nanopores, can be assembled by protein ion channels through genetic engineering or be artificially fabricated on solid substrates using fashion nanotechnology. When target molecules interact with the functionalized lumen of a nanopore, they characteristically block the ion pathway. The resulting conductance changes allow for identification of single molecules and quantification of target species in the mixture. In this review, we first overview nanopore-based sensory techniques that have been created for the detection of myriad biomedical targets, from metal ions, drug compounds, and cellular second messengers to proteins and DNA. Then we introduce our recent discoveries in nanopore single molecule detection: (1) using the protein nanopore to study folding/unfolding of the G-quadruplex aptamer; (2) creating a portable and durable biochip that is integrated with a single-protein pore sensor (this chip is compared with recently developed protein pore sensors based on stabilized bilayers on glass nanopore membranes and droplet interface bilayer); and (3) creating a glass nanopore-terminated probe for single-molecule DNA detection, chiral enantiomer discrimination, and identification of the bioterrorist agent ricin with an aptamer-encoded nanopore. PMID:20174694

Nanopore Electrochemistry: A Nexus for Molecular Control of Electron Transfer Reactions

PubMed Central

2018-01-01

Pore-based structures occur widely in living organisms. Ion channels embedded in cell membranes, for example, provide pathways, where electron and proton transfer are coupled to the exchange of vital molecules. Learning from mother nature, a recent surge in activity has focused on artificial nanopore architectures to effect electrochemical transformations not accessible in larger structures. Here, we highlight these exciting advances. Starting with a brief overview of nanopore electrodes, including the early history and development of nanopore sensing based on nanopore-confined electrochemistry, we address the core concepts and special characteristics of nanopores in electron transfer. We describe nanopore-based electrochemical sensing and processing, discuss performance limits and challenges, and conclude with an outlook for next-generation nanopore electrode sensing platforms and the opportunities they present. PMID:29392173

Molecular transport through large-diameter DNA nanopores

NASA Astrophysics Data System (ADS)

Krishnan, Swati; Ziegler, Daniela; Arnaut, Vera; Martin, Thomas G.; Kapsner, Korbinian; Henneberg, Katharina; Bausch, Andreas R.; Dietz, Hendrik; Simmel, Friedrich C.

2016-09-01

DNA-based nanopores are synthetic biomolecular membrane pores, whose geometry and chemical functionality can be tuned using the tools of DNA nanotechnology, making them promising molecular devices for applications in single-molecule biosensing and synthetic biology. Here we introduce a large DNA membrane channel with an ~4 nm diameter pore, which has stable electrical properties and spontaneously inserts into flat lipid bilayer membranes. Membrane incorporation is facilitated by a large number of hydrophobic functionalizations or, alternatively, streptavidin linkages between biotinylated channels and lipids. The channel displays an Ohmic conductance of ~3 nS, consistent with its size, and allows electrically driven translocation of single-stranded and double-stranded DNA analytes. Using confocal microscopy and a dye influx assay, we demonstrate the spontaneous formation of membrane pores in giant unilamellar vesicles. Pores can be created both in an outside-in and an inside-out configuration.

Fundamental transport mechanisms, fabrication and potential applications of nanoporous atomically thin membranes.

PubMed

Wang, Luda; Boutilier, Michael S H; Kidambi, Piran R; Jang, Doojoon; Hadjiconstantinou, Nicolas G; Karnik, Rohit

2017-06-06

Graphene and other two-dimensional materials offer a new approach to controlling mass transport at the nanoscale. These materials can sustain nanoscale pores in their rigid lattices and due to their minimum possible material thickness, high mechanical strength and chemical robustness, they could be used to address persistent challenges in membrane separations. Here we discuss theoretical and experimental developments in the emerging field of nanoporous atomically thin membranes, focusing on the fundamental mechanisms of gas- and liquid-phase transport, membrane fabrication techniques and advances towards practical application. We highlight potential functional characteristics of the membranes and discuss applications where they are expected to offer advantages. Finally, we outline the major scientific questions and technological challenges that need to be addressed to bridge the gap from theoretical simulations and proof-of-concept experiments to real-world applications.

Experimental proof of the existence of a Widom line based on peculiarities of the behavior of hydrogen in nanoporous silicate at -45°C and atmospheric pressure

NASA Astrophysics Data System (ADS)

Bordonskii, G. S.; Gurulev, A. A.

2017-04-01

We have experimentally studied the thermal and microwave properties of a nanoporous medium (silica gel) with hydrogen-filled pores. On cooling down to about -45°C at atmospheric pressure, the system exhibited chemical transformations, a first-order phase transition with heat evolution, and a sharp change in the power of microwave radiation at 34 GHz transmitted through a sample. It is concluded that this point on the phase diagram corresponds to a point on the Widom line featuring sharp increase in fluctuations of the entropy and density of supercooled water formed during hydrogen interaction with the surface of pores in silica gel. These results confirm the existence of a second critical point of water, from which the Widom line originates.

Pore Characterization of Shale Rock and Shale Interaction with Fluids at Reservoir Pressure-Temperature Conditions Using Small-Angle Neutron Scattering

NASA Astrophysics Data System (ADS)

Ding, M.; Hjelm, R.; Watkins, E.; Xu, H.; Pawar, R.

2015-12-01

Oil/gas produced from unconventional reservoirs has become strategically important for the US domestic energy independence. In unconventional realm, hydrocarbons are generated and stored in nanopores media ranging from a few to hundreds of nanometers. Fundamental knowledge of coupled thermo-hydro-mechanical-chemical (THMC) processes that control fluid flow and propagation within nano-pore confinement is critical for maximizing unconventional oil/gas production. The size and confinement of the nanometer pores creates many complex rock-fluid interface interactions. It is imperative to promote innovative experimental studies to decipher physical and chemical processes at the nanopore scale that govern hydrocarbon generation and mass transport of hydrocarbon mixtures in tight shale and other low permeability formations at reservoir pressure-temperature conditions. We have carried out laboratory investigations exploring quantitative relationship between pore characteristics of the Wolfcamp shale from Western Texas and the shale interaction with fluids at reservoir P-T conditions using small-angle neutron scattering (SANS). We have performed SANS measurements of the shale rock in single fluid (e.g., H2O and D2O) and multifluid (CH4/(30% H2O+70% D2O)) systems at various pressures up to 20000 psi and temperature up to 150 oF. Figure 1 shows our SANS data at different pressures with H2O as the pressure medium. Our data analysis using IRENA software suggests that the principal changes of pore volume in the shale occurred on smaller than 50 nm pores and pressure at 5000 psi (Figure 2). Our results also suggest that with increasing P, more water flows into pores; with decreasing P, water is retained in the pores.

Statistical mechanical model of gas adsorption in porous crystals with dynamic moieties

PubMed Central

Braun, Efrem; Carraro, Carlo; Smit, Berend

2017-01-01

Some nanoporous, crystalline materials possess dynamic constituents, for example, rotatable moieties. These moieties can undergo a conformation change in response to the adsorption of guest molecules, which qualitatively impacts adsorption behavior. We pose and solve a statistical mechanical model of gas adsorption in a porous crystal whose cages share a common ligand that can adopt two distinct rotational conformations. Guest molecules incentivize the ligands to adopt a different rotational configuration than maintained in the empty host. Our model captures inflections, steps, and hysteresis that can arise in the adsorption isotherm as a signature of the rotating ligands. The insights disclosed by our simple model contribute a more intimate understanding of the response and consequence of rotating ligands integrated into porous materials to harness them for gas storage and separations, chemical sensing, drug delivery, catalysis, and nanoscale devices. Particularly, our model reveals design strategies to exploit these moving constituents and engineer improved adsorbents with intrinsic thermal management for pressure-swing adsorption processes. PMID:28049851

Statistical mechanical model of gas adsorption in porous crystals with dynamic moieties.

PubMed

Simon, Cory M; Braun, Efrem; Carraro, Carlo; Smit, Berend

2017-01-17

Some nanoporous, crystalline materials possess dynamic constituents, for example, rotatable moieties. These moieties can undergo a conformation change in response to the adsorption of guest molecules, which qualitatively impacts adsorption behavior. We pose and solve a statistical mechanical model of gas adsorption in a porous crystal whose cages share a common ligand that can adopt two distinct rotational conformations. Guest molecules incentivize the ligands to adopt a different rotational configuration than maintained in the empty host. Our model captures inflections, steps, and hysteresis that can arise in the adsorption isotherm as a signature of the rotating ligands. The insights disclosed by our simple model contribute a more intimate understanding of the response and consequence of rotating ligands integrated into porous materials to harness them for gas storage and separations, chemical sensing, drug delivery, catalysis, and nanoscale devices. Particularly, our model reveals design strategies to exploit these moving constituents and engineer improved adsorbents with intrinsic thermal management for pressure-swing adsorption processes.

Integrating Sub-3 nm Plasmonic Gaps into Solid-State Nanopores.

PubMed

Shi, Xin; Verschueren, Daniel; Pud, Sergii; Dekker, Cees

2018-05-01

Plasmonic nanopores combine the advantages of nanopore sensing and surface plasmon resonances by introducing confined electromagnetic fields to a solid-state nanopore. Ultrasmall nanogaps between metallic nanoantennas can generate the extremely enhanced localized electromagnetic fields necessary for single-molecule optical sensing and manipulation. Challenges in fabrication, however, hamper the integration of such nanogaps into nanopores. Here, a top-down approach for integrating a plasmonic antenna with an ultrasmall nanogap into a solid-state nanopore is reported. Employing a two-step e-beam lithography process, the reproducible fabrication of nanogaps down to a sub-1 nm scale is demonstrated. Subsequently, nanopores are drilled through the 20 nm SiN membrane at the center of the nanogap using focused-electron-beam sculpting with a transmission electron microscope, at the expense of a slight gap expansion for the smallest gaps. Using this approach, sub-3 nm nanogaps can be readily fabricated on solid-state nanopores. The functionality of these plasmonic nanopores for single-molecule detection is shown by performing DNA translocations. These integrated devices can generate intense electromagnetic fields at the entrance of the nanopore and can be expected to find applications in nanopore-based single-molecule trapping and optical sensing. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanopore fabricated in pyramidal HfO2 film by dielectric breakdown method

NASA Astrophysics Data System (ADS)

Wang, Yifan; Chen, Qi; Deng, Tao; Liu, Zewen

2017-10-01

The dielectric breakdown method provides an innovative solution to fabricate solid-state nanopores on insulating films. A nanopore generation event via this method is considered to be caused by random charged traps (i.e., structural defects) and high electric fields in the membrane. Thus, the position and number of nanopores on planar films prepared by the dielectric breakdown method is hard to control. In this paper, we propose to fabricate nanopores on pyramidal HfO2 films (10-nm and 15-nm-thick) to improve the ability to control the location and number during the fabrication process. Since the electric field intensity gets enhanced at the corners of the pyramid-shaped film, the probability of nanopore occurrence at vertex and edge areas increases. This priority of appearance provides us chance to control the location and number of nanopores by monitoring a sudden irreversible discrete increase in current. The experimental results showed that the probability of nanopore occurrence decreases in an order from the vertex area, the edge area to the side face area. The sizes of nanopores ranging from 30 nm to 10 nm were obtained. Nanopores fabricated on the pyramid-shaped HfO2 film also showed an obvious ion current rectification characteristic, which might improve the nanopore performance as a biomolecule sequencing platform.

Biological and chemical sensors based on graphene materials.

PubMed

Liu, Yuxin; Dong, Xiaochen; Chen, Peng

2012-03-21

Owing to their extraordinary electrical, chemical, optical, mechanical and structural properties, graphene and its derivatives have stimulated exploding interests in their sensor applications ever since the first isolation of free-standing graphene sheets in year 2004. This article critically and comprehensively reviews the emerging graphene-based electrochemical sensors, electronic sensors, optical sensors, and nanopore sensors for biological or chemical detection. We emphasize on the underlying detection (or signal transduction) mechanisms, the unique roles and advantages of the used graphene materials. Properties and preparations of different graphene materials, their functionalizations are also comparatively discussed in view of sensor development. Finally, the perspective and current challenges of graphene sensors are outlined (312 references).

Discrimination of three types of homopolymers in single-stranded DNA with solid-state nanopores through external control of the DNA motion.

PubMed

Akahori, Rena; Yanagi, Itaru; Goto, Yusuke; Harada, Kunio; Yokoi, Takahide; Takeda, Ken-Ichi

2017-08-22

To achieve DNA sequencing with solid-state nanopores, the speed of the DNA in the nanopore must be controlled to obtain sequence-specific signals. In this study, we fabricated a nanopore-sensing system equipped with a DNA motion controller. DNA strands were immobilized on a Si probe, and approach of this probe to the nanopore vicinity could be controlled using a piezo actuator and stepper motor. The area of the Si probe was larger than the area of the membrane, which meant that the immobilized DNA could enter the nanopore without the need for the probe to scan to determine the location of the nanopore in the membrane. We demonstrated that a single-stranded DNA could be inserted into and removed from a nanopore in our experimental system. The number of different ionic-current levels observed while DNA remained in the nanopore corresponded to the number of different types of homopolymers in the DNA.

Large apparent electric size of solid-state nanopores due to spatially extended surface conduction.

PubMed

Lee, Choongyeop; Joly, Laurent; Siria, Alessandro; Biance, Anne-Laure; Fulcrand, Rémy; Bocquet, Lydéric

2012-08-08

Ion transport through nanopores drilled in thin membranes is central to numerous applications, including biosensing and ion selective membranes. This paper reports experiments, numerical calculations, and theoretical predictions demonstrating an unexpectedly large ionic conduction in solid-state nanopores, taking its origin in anomalous entrance effects. In contrast to naive expectations based on analogies with electric circuits, the surface conductance inside the nanopore is shown to perturb the three-dimensional electric current streamlines far outside the nanopore in order to meet charge conservation at the pore entrance. This unexpected contribution to the ionic conductance can be interpreted in terms of an apparent electric size of the solid-state nanopore, which is much larger than its geometric counterpart whenever the number of charges carried by the nanopore surface exceeds its bulk counterpart. This apparent electric size, which can reach hundreds of nanometers, can have a major impact on the electrical detection of translocation events through nanopores, as well as for ionic transport in biological nanopores.

Reaching the Ionic Current Detection Limit in Silicon-Based Nanopores

NASA Astrophysics Data System (ADS)

Puster, Matthew; Rodriguez-Manzo, Julio Alejandro; Nicolai, Adrien; Meunier, Vincent; Drndic, Marija

2015-03-01

Solid-state nanopores act as single-molecule sensors whereby passage of an individual molecule in aqueous electrolyte through a nanopore is registered as a change in ionic conductance (ΔG). Future nanopore applications such as DNA sequencing at high bandwidth require high ΔG for optimal signal-to-noise ratio. Reducing the nanopore diameter and thickness increase ΔG. Molecule size limits the diameter, thus efforts concentrate on minimizing the thickness by thinning oxide/nitride films or using 2D materials. Weighted by electrolyte conductivity the highest ΔG reported to date for DNA translocations were obtained with nanopores made in oxide/nitride films. We present a controlled electron irradiation technique to thin such films to the limit of their stability, producing nanopores tailored to molecule size in amorphous Si with thicknesses less than 2 nm. We compare ΔG values with results found in the literature for DNA translocation through these nanopores, where access resistance becomes comparable to the resistance through the nanopore itself.

PREFACE New developments in nanopore research—from fundamentals to applications New developments in nanopore research—from fundamentals to applications

NASA Astrophysics Data System (ADS)

Albrecht, Tim; Edel, Joshua B.; Winterhalter, Mathias

2010-11-01

Biological and solid-state nanopores are an exciting field of research, which has seen a rapid development over the last 10 to 20 years. Activities in this area range from theoretical and experimental work on the underlying fundamental (bio)physics to applications in single-molecule biosensing. And while the prospect of DNA sequencing continues to be a major driving force, other applications with potentially similar impact begin to emerge, for example the detection of small molecules, proteins, protein/protein and protein/DNA complexes, and RNA to name just a few. It has also become apparent that both classes of nanopore devices have intrinsic advantages and disadvantages; hybrid structures combining the better of the two worlds would be a logical consequence and are beginning to appear in the literature. Many other highly innovative ideas and concepts continue to emerge and the number of nanopore-related publications has increased drastically over recent years. We found that more than 100 research groups worldwide are active in this area; several commercial settings are in the process of translating fundamental research into real-life applications. We therefore felt that now is the right time to showcase these new developments in a special issue: to inspire researchers active in the field, to liberate inherent synergies, and not least, to demonstrate to the outside world the current state-of-the-art and future opportunities. The title 'New developments in nanopore research—from fundamentals to applications' in some way reflects these ambitions and, even though not everyone invited was able to contribute, we were able to assemble 34 high-quality research papers from all over the world. We would like to acknowledge and thank all the contributors for their submissions, which made this special issue possible in the first place. Moreover, we would like to thank the staff at IOP Publishing for helping us with the administrative aspects and for coordinating the refereeing process, and Ms Natalia Goehring for the beautiful cover artwork. Finally, to the readers, we hope you find this special issue a valuable source of information and insight into the field of nanopores. New developments in nanopore research—from fundamentals to applications contents Mathematical modeling and simulation of nanopore blocking by precipitation M-T Wolfram, M Burger and Z S Siwy Protein conducting nanopores Anke Harsman, Vivien Krüger, Philipp Bartsch, Alf Honigmann, Oliver Schmidt, Sanjana Rao, Christof Meisinger and Richard Wagner Electrically sensing protease activity with nanopores Mikiembo Kukwikila and Stefan Howorka Electrical characterization of DNA-functionalized solid state nanopores for bio-sensing V Mussi, P Fanzio, L Repetto, G Firpo, P Scaruffi, S Stigliani, M Menotta, M Magnani, G P Tonini and U Valbusa Automatable lipid bilayer formation and ion channel measurement using sessile droplets J L Poulos, S A Portonovo, H Bang and J J Schmidt Critical assessment of OmpF channel selectivity: merging information from different experimental protocols M L López, E García-Giménez, V M Aguilella and A Alcaraz Chemically modified solid state nanopores for high throughput nanoparticle separation Anmiv S Prabhu, Talukder Zaki N Jubery, Kevin J Freedman, Rafael Mulero, Prashanta Dutta and Min Jun Kim Changes in ion channel geometry resolved to sub-ångström precision via single molecule mass spectrometry Joseph W F Robertson, John J Kasianowicz and Joseph E Reiner Entropic transport of finite size particles W Riefler, G Schmid, P S Burada and P Hänggi Osmotic stress regulates the strength and kinetics of sugar binding to the maltoporin channel Philip A Gurnev, Daniel Harries, V Adrian Parsegian and Sergey M Bezrukov Detection of urea-induced internal denaturation of dsDNA using solid-state nanoporesn Alon Singer, Heiko Kuhn, Maxim Frank-Kamenetskii and Amit Meller Translocation events in a single-walled carbon nanotube Jin He, Hao Liu, Pei Pang, Di Cao and Stuart Lindsay Probing DNA with micro- and nanocapillaries and optical tweezers L J Steinbock, O Otto, D R Skarstam, S Jahn, C Chimerel, J L Gornall and U F Keyser Fabrication of nanopores with embedded annular electrodes and transverse carbon nanotube electrodes Zhijun Jiang, Mirna Mihovilovic, Jason Chan and Derek Stein Fabrication and electrical characterization of a pore-cavity-pore device D Pedone, M Langecker, A M Münzer, R Wei, R D Nagel and U Rant Use of tunable nanopore blockade rates to investigate colloidal dispersions G R Willmott, R Vogel, S S C Yu, L G Groenewegen, G S Roberts, D Kozak, W Anderson and M Trau Facilitated translocation of polypeptides through a single nanopore Robert Bikwemu, Aaron J Wolfe, Xiangjun Xing and Liviu Movileanu Mechanistic insight into gramicidin-based detection of protein-ligand interactions via sensitized photoinactivation Tatyana I Rokitskaya, Michael X Macrae, Steven Blake, Natalya S Egorova, Elena A Kotova, Jerry Yang and Yuri N Antonenko Sequence-dependent unfolding kinetics of DNA hairpins studied by nanopore force spectroscopy Stephan Renner, Andrey Bessonov, Ulrich Gerland and Friedrich C Simmel Hydration properties of mechanosensitive channel pores define the energetics of gating A Anishkin, B Akitake, K Kamaraju, C-S Chiang and S Sukharev Dynamic translocation of ligand-complexed DNA through solid-state nanopores with optical tweezers Andy Sischka, Andre Spiering, Maryam Khaksar, Miriam Laxa, Janine König, Karl-Josef Dietz and Dario Anselmetti Force fluctuations assist nanopore unzipping of DNA V Viasnoff, N Chiaruttini, J Muzard and U Bockelmann Control and reversal of the electrophoretic force on DNA in a charged nanopore Binquan Luan and Aleksei Aksimentiev The properties of the outer membrane localized Lipid A transporter LptD Raimund Haarmann, Mohamed Ibrahim, Mara Stevanovic, Rolf Bredemeier and Enrico Schleiff Structural and dynamical properties of the porins OmpF and OmpC: insights from molecular simulations Amit Kumar, Eric Hajjar, Paolo Ruggerone and Matteo Ceccarelli Dehydration and ionic conductance quantization in nanopores Michael Zwolak, James Wilson and Massimiliano Di Ventra Current oscillations generated by precipitate formation in the mixing zone between two solutions inside a nanopore Erik C Yusko, Yazan N Billeh and Michael Mayer Precise electrochemical fabrication of sub-20 nm solid-state nanopores for single-molecule biosensing Mariam Ayub, Aleksandar Ivanov, Jongin Hong, Phillip Kuhn, Emanuele Instuli, Joshua B Edel and Tim Albrecht The distribution of DNA translocation times in solid-state nanopores Jiali Li and David S Talaga Crowding effects in non-equilibrium transport through nano-channels A Zilman and G Bel Permeation through nanochannels: revealing fast kinetics Kozhinjampara R Mahendran, Pratik Raj Singh, Jürgen Arning, Stefan Stolte, Ulrich Kleinekathöfer and Mathias Winterhalter LILBID-mass spectrometry of the mitochondrial preprotein translocase TOM Frauke Mager, Lucie Sokolova, Julia Lintzel, Bernhard Brutschy and Stephan Nussberger Evidence that small proteins translocate through silicon nitride pores in a folded conformation Radu I Stefureac, Dhruti Trivedi, Andre Marziali and Jeremy S Lee Methods for controlling the pore properties of ultra-thin nanocrystalline silicon membranes D Z Fang, C C Striemer, T R Gaborski, J L McGrath and P M Fauchet

Controlled formation of closed-edge nanopores in graphene

NASA Astrophysics Data System (ADS)

He, Kuang; Robertson, Alex W.; Gong, Chuncheng; Allen, Christopher S.; Xu, Qiang; Zandbergen, Henny; Grossman, Jeffrey C.; Kirkland, Angus I.; Warner, Jamie H.

2015-07-01

Dangling bonds at the edge of a nanopore in monolayer graphene make it susceptible to back-filling at low temperatures from atmospheric hydrocarbons, leading to potential instability for nanopore applications, such as DNA sequencing. We show that closed edge nanopores in bilayer graphene are robust to back-filling under atmospheric conditions for days. A controlled method for closed edge nanopore formation starting from monolayer graphene is reported using an in situ heating holder and electron beam irradiation within an aberration-corrected transmission electron microscopy. Tailoring of closed-edge nanopore sizes is demonstrated from 1.4-7.4 nm. These results should provide mechanisms for improving the stability of nanopores in graphene for a wide range of applications involving mass transport.Dangling bonds at the edge of a nanopore in monolayer graphene make it susceptible to back-filling at low temperatures from atmospheric hydrocarbons, leading to potential instability for nanopore applications, such as DNA sequencing. We show that closed edge nanopores in bilayer graphene are robust to back-filling under atmospheric conditions for days. A controlled method for closed edge nanopore formation starting from monolayer graphene is reported using an in situ heating holder and electron beam irradiation within an aberration-corrected transmission electron microscopy. Tailoring of closed-edge nanopore sizes is demonstrated from 1.4-7.4 nm. These results should provide mechanisms for improving the stability of nanopores in graphene for a wide range of applications involving mass transport. Electronic supplementary information (ESI) available: Low magnification images, image processing techniques employed, modelling and simulation of closed edge nanoribbon, comprehensive AC-TEM dataset, and supporting analysis. See DOI: 10.1039/c5nr02277k

Ionic-Liquid-Infused Nanostructures as Repellent Surfaces.

PubMed

Galvan, Yaraset; Phillips, Katherine R; Haumann, Marco; Wasserscheid, Peter; Zarraga, Ramon; Vogel, Nicolas

2018-06-12

In order to prepare lubricant-infused repellent coatings on silica nanostructures using low vapor pressure ionic liquids as lubricants, we study the wetting behavior of a set of imidazolium-based ionic liquids with different alkyl side chains as a function of the applied surface functionalities. We take advantage of the structural color of inverse opals prepared from a colloidal coassembly technique to study the infiltration of ionic liquids into these nanoporous structures. We find that the more hydrophobic ionic liquids with butyl and hexyl side chains can completely infiltrate inverse opals functionalized with mixed self-assembled monolayers composed of imidazole groups and aliphatic hydrocarbon chains, which we introduce via silane chemistry. These molecular species reflect the chemical nature of the ionic liquid, thereby increasing the affinity between the liquid and solid surface. The mixed surface chemistry provides sufficiently small contact angles with the ionic liquid to infiltrate the nanopores while maximizing the contact angle with water. As a result, the mixed monolayers enable the design of a stable ionic liquid/solid interface that is able to repel water as a test liquid. Our results underline the importance of matching chemical affinities to predict and control the wetting behavior in complex, multiphase systems.

Color filters based on a nanoporous Al-AAO resonator featuring structure tolerant color saturation.

PubMed

Yue, Wenjing; Li, Yang; Wang, Cong; Yao, Zhao; Lee, Sang-Shin; Kim, Nam-Young

2015-10-19

Reflection type subtractive tri-color filters, enabling metal-thickness tolerant high color saturation, were proposed and demonstrated capitalizing on a nanoporous metal-dielectric-metal (MDM) resonant structure, which comprises a cavity made of self-assembled nanoporous anodic aluminum oxide (AAO), sandwiched between an Al film of the same nanoporous configuration and a highly reflective aluminum (Al) substrate. For the proposed filter, the output color was easily determined by controlling the resonance wavelength via the thickness of the porous AAO cavity. In particular, the spectral response was deemed to exhibit a near-zero resonant dip, thereby achieving enhanced color saturation, which was stably maintained irrespective of the thickness of the porous Al film, due to its reduced effective refractive index. In order to manufacture the proposed color filters on a large scale, a porous Al film of hexagonal lattice configuration was integrated with an identically porous self-assembled AAO layer, which has been grown on an Al substrate. For the realized tri-color filters for cyan, magenta, and yellow (CMY), having a 15-nm Al film, near-zero reflection dips were observed to be centered at the wavelengths of 436, 500, and 600 nm, respectively. The resulting enhanced color saturation was stably maintained even though the variations were as large as 10 nm in the metal thickness.

Chemoresponsive Colloidosomes via Ag⁺ Soldering of Surface-Assembled Nanoparticle Monolayers.

PubMed

Liu, Miao; Tian, Qian; Li, Yulin; You, Bo; Xu, An; Deng, Zhaoxiang

2015-04-28

Colloidosomes with a hollow interior and a porous plasmonic shell are highly desired for many applications including nanoreactors, surface-enhanced Raman scattering (SERS), photothermal therapy, and controlled drug release. We herein report a silica nanosphere-templated electrostatic self-assembly in conjunction with a newly developed Ag(+) soldering to fabricate gold colloidosomes toward multifunctionality and stimuli-responsibility. The gold colloidosomes are capable of capturing a nanosized object and releasing it via structural dissociation upon responding to a biochemical input (GSH, glutathione) at a concentration close to its cellular level. In addition, the colloidosomes have a tunable nanoporous shell composed of strongly coupled gold nanoparticles, which exhibit broadened near-infrared plasmon resonance. These features along with the simplicity and high tunability of the fabrication process make the gold colloidosomes quite promising for applications in a chemical or cellular environment.

Stretching and Controlled Motion of Single-Stranded DNA in Locally-Heated Solid-State Nanopores

PubMed Central

Belkin, Maxim; Maffeo, Christopher; Wells, David B.

2013-01-01

Practical applications of solid-state nanopores for DNA detection and sequencing require the electrophoretic motion of DNA through the nanopores to be precisely controlled. Controlling the motion of single-stranded DNA presents a particular challenge, in part because of the multitude of conformations that a DNA strand can adopt in a nanopore. Through continuum, coarse-grained and atomistic modeling, we demonstrate that local heating of the nanopore volume can be used to alter the electrophoretic mobility and conformation of single-stranded DNA. In the nanopore systems considered, the temperature near the nanopore is modulated via a nanometer-size heater element that can be radiatively switched on and off. The local enhancement of temperature produces considerable stretching of the DNA fragment confined within the nanopore. Such stretching is reversible, so that the conformation of DNA can be toggled between compact (local heating is off) and extended (local heating is on) states. The effective thermophoretic force acting on single-stranded DNA in the vicinity of the nanopore is found to be sufficiently large (4–8 pN) to affect such changes in the DNA conformation. The local heating of the nanopore volume is observed to promote single-file translocation of DNA strands at transmembrane biases as low as 10 mV, which opens new avenues for using solid-state nanopores for detection and sequencing of DNA. PMID:23876013

Study on the Characteristics of Gas Molecular Mean Free Path in Nanopores by Molecular Dynamics Simulations

PubMed Central

Liu, Qixin; Cai, Zhiyong

2014-01-01

This paper presents studies on the characteristics of gas molecular mean free path in nanopores by molecular dynamics simulation. Our study results indicate that the mean free path of all molecules in nanopores depend on both the radius of the nanopore and the gas-solid interaction strength. Besides mean free path of all molecules in the nanopore, this paper highlights the gas molecular mean free path at different positions of the nanopore and the anisotropy of the gas molecular mean free path at nanopores. The molecular mean free path varies with the molecule’s distance from the center of the nanopore. The least value of the mean free path occurs at the wall surface of the nanopore. The present paper found that the gas molecular mean free path is anisotropic when gas is confined in nanopores. The radial gas molecular mean free path is much smaller than the mean free path including all molecular collisions occuring in three directions. Our study results also indicate that when gas is confined in nanopores the gas molecule number density does not affect the gas molecular mean free path in the same way as it does for the gas in unbounded space. These study results may bring new insights into understanding the gas flow’s characteristic at nanoscale. PMID:25046745

Modification and Utilization of Nanoporous Gold for Loading and Release of Drugs

NASA Astrophysics Data System (ADS)

Al-badri, Ibtisam

Nanoporous gold (np-Au) is a sponge-like structure of gold, which can be created by removing the less noble element from the precursor alloy, most typically silver or copper, using different chemical or electrochemical methods. It consists of interconnected ligaments and gaps between the ligaments, whose width can range from a few nanometers to a few hundreds of nanometers, creating a high surface area-to-volume ratio. Due to its many important properties (e.g., conductivity, high surface area-to-volume ratio, plasmonic response, biocompatibility, chemically inertness, and physically robustness), np-Au is suitable for different types of applications, including as a transducer for biosensors, in catalysis, for biomolecule separation, as a substrate for enzyme immobilization, and in drug delivery. The widths of the ligaments and gaps of np-Au can be easily tuned by varying conditions during the pre- or post-production process, for example, time kept in an acid bath and post-annealing (e.g. thermal, chemical, and electrochemical), depending on the requirement of the study. Thermal annealing is a commonly used process for tuning the ligaments and pore size of np-Au. However, the effects of thermal annealing on modification of ligaments and gaps sizes are not completely understood and more research needs to be done. Herein, we have explored the effect of annealing time and thickness of the np-Au sample on modification of ligaments and gaps. Furthermore, we used the electroless plating method to cover the pores or gaps partially on the surface without modifying the interior of np-Au. As-prepared np-Au was then studied as a platform for molecular loading and releasing kinetics for the possible use in drug delivery. We have found that simply applying the electroless deposition for 1 to 5 min can drastically decrease the rate of release of the molecules, and flow cell-based loading is the preferred way to load the molecules inside np-Au compared to the static method. The structure of the np-Au monoliths before and after the modification was characterized using Energy-Dispersive X-ray Spectroscopy (EDS) and scanning electron microscopy (SEM), whereas the molecular loading and releasing studies were performed using UV-Vis spectrophotometer.

Nanopore DNA sensors based on dendrimer-modified nanopipettes.

PubMed

Fu, Yaqin; Tokuhisa, Hideo; Baker, Lane A

2009-08-28

A dendrimer-modified nanopipette is used to detect hybridization of a specific DNA sequence through evaluation of the extent of rectification of ion currents observed in the measured current-voltage response.

Ultra-Thin Solid-State Nanopores: Fabrication and Applications

NASA Astrophysics Data System (ADS)

Kuan, Aaron Tzeyang

Solid-state nanopores are a nanofluidic platform with unique advantages for single-molecule analysis and filtration applications. However, significant improvements in device performance and scalable fabrication methods are needed to make nanopore devices competitive with existing technologies. This dissertation investigates the potential advantages of ultra-thin nanopores in which the thickness of the membrane is significantly smaller than the nanopore diameter. Novel, scalable fabrication methods were first developed and then utilized to examine device performance for water filtration and single molecule sensing applications. Fabrication of nanometer-thin pores in silicon nitride membranes was achieved using a feedback-controlled ion beam method in which ion sputtering is arrested upon detection of the first few ions that drill through the membrane. Performing fabrication at liquid nitrogen temperatures prevents surface atom rearrangements that have previously complicated similar processes. A novel cross-sectional imaging method was also developed to allow careful examination of the full nanopore geometry. Atomically-thin graphene nanopores were fabricated via an electrical pulse method in which sub-microsecond electrical pulses applied across a graphene membrane in electrolyte solution are used to create a defect in the membrane and controllably enlarge it into a nanopore. This method dramatically increases the accuracy and reliability of graphene nanopore production, allowing consistent production of single nanopores down to subnanometer sizes. In filtration applications in which nanopores are used to selectively restrict the passage of dissolved contaminants, ultra-thin nanopores minimize the flow resistance, increasing throughput and energy-efficiency. The ability of graphene nanopores to separate different ions was characterized via ionic conductance and reversal potential measurements. Graphene nanopores were observed to conduct cations preferentially over anions with selectivity ratios of 100 or higher for pores as large as 20 nm in diameter, suggesting that porous graphene membranes can be used to create highly effective cation exchange membranes for electrodialysis filtration. These surprisingly high selectivities cannot be explained by current models of ionic conduction in graphene nanopores, motivating the development of a new model in which elevated concentrations of mobile cations near the graphene surface generate additional ion selectivity.

The relationship between substrate morphology and biological performances of nano-silver-loaded dopamine coatings on titanium surfaces

PubMed Central

Zhang, Weibo; Wang, Shuang; Ge, Shaohua; Ji, Ping

2018-01-01

Biomedical device-associated infection (BAI) and lack of osseointegration are the main causes of implant failure. Therefore, it is imperative for implants not only to depress microbial activity and biofilm colonization but also to prompt osteoblast functions and osseointegration. As part of the coating development for implants, the interest of in vitro studies on the interaction between implant substrate morphology and the coating's biological performances is growing. In this study, by harnessing the adhesion and reactivity of bioinspired polydopamine, nano-silver was successfully anchored onto micro/nanoporous as well as smooth titanium surfaces to analyse the effect of substrate morphology on biological performances of the coatings. Compared with the smooth surface, a small size of nano-silver and high silver content was found on the micro/nanoporous surface. More mineralization happened on the coating on the micro/nanoporous structure than on the smooth surface, which led to a more rapid decrease of silver release from the micro/nanoporous surface. Antimicrobial tests indicated that both surfaces with resulting coating inhibit microbial colonization on them and growth around them, indicating that the coating eliminates the shortcoming of the porous structure which render the implant extremely susceptible to BAI. Besides, the multiple osteoblast responses of nano-silver-loaded dopamine coatings on both surfaces, i.e. attachment, proliferation and differentiation, have deteriorated, however the mineralized surfaces of these coatings stimulated osteoblast proliferation and differentiation, especially for the micro/nanoporous surface. Therefore, nano-silver-loaded dopamine coatings on micro/nanoporous substratum may not only reduce the risk of infection but also facilitate mineralization during the early post-operative period and then promote osseointegration owing to the good osteoblast-biocompatibility of the mineralized surface. These results clearly highlight the influence of the substrate morphology on the biological performances of implant coating. PMID:29765680

Synthesis of nanostructured porous silica coatings on titanium and their cell adhesive and osteogenic differentiation properties.

PubMed

Inzunza, Débora; Covarrubias, Cristian; Von Marttens, Alfredo; Leighton, Yerko; Carvajal, Juan Carlos; Valenzuela, Francisco; Díaz-Dosque, Mario; Méndez, Nicolás; Martínez, Constanza; Pino, Ana María; Rodríguez, Juan Pablo; Cáceres, Mónica; Smith, Patricio

2014-01-01

Nanostructured porous silica coatings were synthesized on titanium by the combined sol-gel and evaporation-induced self-assembly process. The silica-coating structures were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and nitrogen sorptometry. The effect of the nanoporous surface on apatite formation in simulated body fluid, protein adsorption, osteoblast cell adhesion behavior, and osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs) is reported. Silica coatings with highly ordered sub-10 nm porosity accelerate early osteoblast adhesive response, a favorable cell response that is attributed to an indirect effect due to the high protein adsorption observed on the large-specific surface area of the nanoporous coating but is also probably due to direct mechanical stimulus from the nanostructured topography. The nanoporous silica coatings, particularly those doped with calcium and phosphate, also promote the osteogenic differentiation of hBMSCs with spontaneous mineral nodule formation in basal conditions. The bioactive surface properties exhibited by the nanostructured porous silica coatings make these materials a promising alternative to improve the osseointegration properties of titanium dental implants and could have future impact on the nanoscale design of implant surfaces. Copyright © 2013 Wiley Periodicals, Inc., a Wiley Company.

A nanoporous gold membrane for sensing applications

PubMed Central

Oo, Swe Zin; Silva, Gloria; Carpignano, Francesca; Noual, Adnane; Pechstedt, Katrin; Mateos, Luis; Grant-Jacob, James A.; Brocklesby, Bill; Horak, Peter; Charlton, Martin; Boden, Stuart A.; Melvin, Tracy

2016-01-01

Design and fabrication of three-dimensionally structured, gold membranes containing hexagonally close-packed microcavities with nanopores in the base, are described. Our aim is to create a nanoporous structure with localized enhancement of the fluorescence or Raman scattering at, and in the nanopore when excited with light of approximately 600 nm, with a view to provide sensitive detection of biomolecules. A range of geometries of the nanopore integrated into hexagonally close-packed assemblies of gold micro-cavities was first evaluated theoretically. The optimal size and shape of the nanopore in a single microcavity were then considered to provide the highest localized plasmon enhancement (of fluorescence or Raman scattering) at the very center of the nanopore for a bioanalyte traversing through. The optimized design was established to be a 1200 nm diameter cavity of 600 nm depth with a 50 nm square nanopore with rounded corners in the base. A gold 3D-structured membrane containing these sized microcavities with the integrated nanopore was successfully fabricated and ‘proof of concept’ Raman scattering experiments are described. PMID:26973809

Modeling the self-assembly of ordered nanoporous materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Monson, Peter; Auerbach, Scott

This report describes progress on a collaborative project on the multiscale modeling of the assembly processes in the synthesis of nanoporous materials. Such materials are of enormous importance in modern technology with application in the chemical process industries, biomedicine and biotechnology as well as microelectronics. The project focuses on two important classes of materials: i) microporous crystalline materials, such as zeolites, and ii) ordered mesoporous materials. In the first case the pores are part of the crystalline structure, while in the second the structures are amorphous on the atomistic length scale but where surfactant templating gives rise to order onmore » the length scale of 2 - 20 nm. We have developed a modeling framework that encompasses both these kinds of materials. Our models focus on the assembly of corner sharing silica tetrahedra in the presence of structure directing agents. We emphasize a balance between sufficient realism in the models and computational tractibility given the complex many-body phenomena. We use both on-lattice and off-lattice models and the primary computational tools are Monte Carlo simulations with sampling techniques and ensembles appropriate to specific situations. Our modeling approach is the first to capture silica polymerization, nanopore crystallization, and mesopore formation through computer-simulated self assembly.« less

Simulation of a model nanopore sensor: Ion competition underlies device behavior.

PubMed

Mádai, Eszter; Valiskó, Mónika; Dallos, András; Boda, Dezső

2017-12-28

We study a model nanopore sensor with which a very low concentration of analyte molecules can be detected on the basis of the selective binding of the analyte molecules to the binding sites on the pore wall. The bound analyte ions partially replace the current-carrier cations in a thermodynamic competition. This competition depends both on the properties of the nanopore and the concentrations of the competing ions (through their chemical potentials). The output signal given by the device is the current reduction caused by the presence of the analyte ions. The concentration of the analyte ions can be determined through calibration curves. We model the binding site with the square-well potential and the electrolyte as charged hard spheres in an implicit background solvent. We study the system with a hybrid method in which we compute the ion flux with the Nernst-Planck (NP) equation coupled with the Local Equilibrium Monte Carlo (LEMC) simulation technique. The resulting NP+LEMC method is able to handle both strong ionic correlations inside the pore (including finite size of ions) and bulk concentrations as low as micromolar. We analyze the effect of bulk ion concentrations, pore parameters, binding site parameters, electrolyte properties, and voltage on the behavior of the device.

Simulation of a model nanopore sensor: Ion competition underlies device behavior

NASA Astrophysics Data System (ADS)

Mádai, Eszter; Valiskó, Mónika; Dallos, András; Boda, Dezső

2017-12-01

We study a model nanopore sensor with which a very low concentration of analyte molecules can be detected on the basis of the selective binding of the analyte molecules to the binding sites on the pore wall. The bound analyte ions partially replace the current-carrier cations in a thermodynamic competition. This competition depends both on the properties of the nanopore and the concentrations of the competing ions (through their chemical potentials). The output signal given by the device is the current reduction caused by the presence of the analyte ions. The concentration of the analyte ions can be determined through calibration curves. We model the binding site with the square-well potential and the electrolyte as charged hard spheres in an implicit background solvent. We study the system with a hybrid method in which we compute the ion flux with the Nernst-Planck (NP) equation coupled with the Local Equilibrium Monte Carlo (LEMC) simulation technique. The resulting NP+LEMC method is able to handle both strong ionic correlations inside the pore (including finite size of ions) and bulk concentrations as low as micromolar. We analyze the effect of bulk ion concentrations, pore parameters, binding site parameters, electrolyte properties, and voltage on the behavior of the device.

Phosphorene-directed self-assembly of asymmetric PS-b-PMMA block copolymer for perpendicularly-oriented sub-10 nm PS nanopore arrays

NASA Astrophysics Data System (ADS)

Zhang, Ziming; Zheng, Lu; Khurram, Muhammad; Yan, Qingfeng

2017-10-01

Few-layer black phosphorus, also known as phosphorene, is a new two-dimensional material which is of enormous interest for applications, mainly in electronics and optoelectronics. Herein, we for the first time employ phosphorene for directing the self-assembly of asymmetric polystyrene-block-polymethylmethacrylate (PS-b-PMMA) block copolymer (BCP) thin film to form the perpendicular orientation of sub-10 nm PS nanopore arrays in a hexagonal fashion normal to the interface. We experimentally demonstrate that none of the PS and PMMA blocks exhibit preferential affinity to the phosphorene-modified surface. Furthermore, the perpendicularly-oriented PS nanostructures almost stay unchanged with the variation of number of layers of few-layer phosphorene nanoflakes between 15-30 layers. Differing from the neutral polymer brushes which are widely used for chemical modification of the silicon substrate, phosphorene provides a novel physical way to control the interfacial interactions between the asymmetric PS-b-PMMA BCP thin film and the silicon substrate. Based on our results, it is possible to build a new scheme for producing sub-10 nm PS nanopore arrays oriented perpendicularly to the few-layer phosphorene nanoflakes. Furthermore, the nanostructural microdomains could serve as a promising nanolithography template for surface patterning of phosphorene nanoflakes.

Realisation and optical engineering of linear variable bandpass filters in nanoporous anodic alumina photonic crystals.

PubMed

Sukarno; Law, Cheryl Suwen; Santos, Abel

2017-06-08

We present the first realisation of linear variable bandpass filters in nanoporous anodic alumina (NAA-LVBPFs) photonic crystal structures. NAA gradient-index filters (NAA-GIFs) are produced by sinusoidal pulse anodisation and used as photonic crystal platforms to generate NAA-LVBPFs. The anodisation period of NAA-GIFs is modified from 650 to 850 s to systematically tune the characteristic photonic stopband of these photonic crystals across the UV-visible-NIR spectrum. Then, the nanoporous structure of NAA-GIFs is gradually widened along the surface under controlled conditions by wet chemical etching using a dip coating approach aiming to create NAA-LVBPFs with finely engineered optical properties. We demonstrate that the characteristic photonic stopband and the iridescent interferometric colour displayed by these photonic crystals can be tuned with precision across the surface of NAA-LVBPFs by adjusting the fabrication and etching conditions. Here, we envisage for the first time the combination of the anodisation period and etching conditions as a cost-competitive, facile, and versatile nanofabrication approach that enables the generation of a broad range of unique LVBPFs covering the spectral regions. These photonic crystal structures open new opportunities for multiple applications, including adaptive optics, hyperspectral imaging, fluorescence diagnostics, spectroscopy, and sensing.

Mechanical stability of heat-treated nanoporous anodic alumina subjected to repetitive mechanical deformation

NASA Astrophysics Data System (ADS)

Bankova, A.; Videkov, V.; Tzaneva, B.; Mitov, M.

2018-03-01

We report studies on the mechanical response and deformation behavior of heat-treated nanoporous anodic alumina using a micro-balance test and experimental test equipment especially designed for this purpose. AAO samples were characterized mechanically by a three-point bending test using a micro-analytical balance. The deformation behavior was studied by repetitive mechanical bending of the AAO membranes using an electronically controlled system. The nanoporous AAO structures were prepared electrochemically from Al sheet substrates using a two-step anodizing technique in oxalic acid followed by heat treatment at 700 °C in air. The morphological study of the aluminum oxide layer after the mechanical tests and mechanical deformation was conducted using scanning electron and optical microscopy, respectively. The experimental results showed that the techniques proposed are simple and accurate; they could, therefore, be combined to constitute a method for mechanical stability assessment of nanostructured AAO films, which are important structural components in the design of MEMS devices and sensors.

d -zero magnetism in nanoporous amorphous alumina membranes

NASA Astrophysics Data System (ADS)

Esmaeily, Amir Sajad; Venkatesan, M.; Sen, S.; Coey, J. M. D.

2018-05-01

Nanoporous alumina membranes produced by mild or hard anodization have a controllable pore surface area up to 400 times that of the membrane itself. They exhibit a temperature-independent and almost anhysteretic saturating response to a magnetic field up to temperatures of 300 K or more. The magnetism, which cannot be explained by the ˜1 ppm of transition-metal impurities present in the membranes, increases with the area of the open nanopores, reaching values of 0.6 Bohr magnetons per square nanometer for mild anodization and 8 Bohr magnetons per square nanometer for the faster hard anodization process. Crystallization of the membrane or treatment with salicylic acid can destroy 90% of the magnetism. The effect is therefore linked with the surfaces of the open pores in the amorphous A l2O3 . Possible explanations in terms of electrons associated with oxygen vacancies (F or F+ centers) are considered. It is concluded that the phenomenon involved is likely to be saturating giant orbital paramagnetism, rather than any sort of collective ferromagnetic spin order.

Nanoporous platinum-cobalt alloy for electrochemical sensing for ethanol, hydrogen peroxide, and glucose.

PubMed

Xu, Caixia; Sun, Fenglei; Gao, Hua; Wang, Jinping

2013-05-30

Nanoporous platinum-cobalt (NP-PtCo) alloy with hierarchical nanostructure is straightforwardly fabricated by dealloying PtCoAl alloy in a mild alkaline solution. Selectively etching Al resulted in a hierarchical three-dimensional network nanostructure with a narrow size distribution at 3 nm. The as-prepared NP-PtCo alloy shows superior performance toward ethanol and hydrogen peroxide (H2O2) with highly sensitive response due to its unique electrocatalytic activity. In addition, NP-PtCo also exhibits excellent amperometric durability and long-term stability for H2O2 as well as a good anti-interference toward ascorbic acid, uric acid, and dopamine. The hierarchical nanoporous architecture in PtCo alloy is also highly active for glucose sensing electrooxidation and sensing in a wide linear range. The NP-PtCo alloy holds great application potential for electrochemical sensing with simple preparation, unique catalytic activity, and high structure stability. Copyright © 2013 Elsevier B.V. All rights reserved.

Conductivity affects nanosecond electrical pulse induced pressure transient formation

NASA Astrophysics Data System (ADS)

Roth, Caleb C.; Barnes, Ronald A.; Ibey, Bennett L.; Beier, Hope T.; Glickman, Randolph D.

2016-03-01

Nanoporation occurs in cells exposed to high amplitude short duration (< 1μs) electrical pulses. The biophysical mechanism(s) responsible for nanoporation is unknown although several theories exist. Current theories focus exclusively on the electrical field, citing electrostriction, water dipole alignment and/or electrodeformation as the primary mechanisms for pore formation. Our group has shown that mechanical forces of substantial magnitude are also generated during nsEP exposures. We hypothesize that these mechanical forces may contribute to pore formation. In this paper, we report that alteration of the conductivity of the exposure solution also altered the level of mechanical forces generated during a nsEP exposure. By reducing the conductivity of the exposure solutions, we found that we could completely eliminate any pressure transients normally created by nsEP exposure. The data collected for this proceeding does not definitively show that the pressure transients previously identified contribute to nanoporation; however; it indicates that conductivity influences both survival and pressure transient formation.

Effect of ultraviolet illumination and ambient gases on the photoluminescence and electrical properties of nanoporous silicon layer for organic vapor sensor.

PubMed

Atiwongsangthong, Narin

2012-08-01

The purpose of this research, the nanoporous silicon layer were fabricated and investigated the physical properties such as photoluminescence and the electrical properties in order to develop organic vapor sensor by using nanoporous silicon. The Changes in the photoluminescence intensity of nanoporous silicon samples are studied during ultraviolet illumination in various ambient gases such as nitrogen, oxigen and vacuum. In this paper, the nanoporous silicon layer was used as organic vapor adsorption and sensing element. The advantage of this device are simple process compatible in silicon technology and usable in room temperature. The structure of this device consists of nanoporous silicon layer which is formed by anodization of silicon wafer in hydrofluoric acid solution and aluminum electrode which deposited on the top of nanoporous silicon layer by evaporator. The nanoporous silicon sensors were placed in a gas chamber with various organic vapor such as ethanol, methanol and isopropyl alcohol. From studying on electrical characteristics of this device, it is found that the nanoporous silicon layer can detect the different organic vapor. Therefore, the nanoporous silicon is important material for organic vapor sensor and it can develop to other applications about gas sensors in the future.

Atomic layer deposition-based functionalization of materials for medical and environmental health applications

PubMed Central

Narayan, Roger J.; Adiga, Shashishekar P.; Pellin, Michael J.; Curtiss, Larry A.; Hryn, Alexander J.; Stafslien, Shane; Chisholm, Bret; Shih, Chun-Che; Shih, Chun-Ming; Lin, Shing-Jong; Su, Yea-Yang; Jin, Chunming; Zhang, Junping; Monteiro-Riviere, Nancy A.; Elam, Jeffrey W.

2010-01-01

Nanoporous alumina membranes exhibit high pore densities, well-controlled and uniform pore sizes, as well as straight pores. Owing to these unusual properties, nanoporous alumina membranes are currently being considered for use in implantable sensor membranes and water purification membranes. Atomic layer deposition is a thin-film growth process that may be used to modify the pore size in a nanoporous alumina membrane while retaining a narrow pore distribution. In addition, films deposited by means of atomic layer deposition may impart improved biological functionality to nanoporous alumina membranes. In this study, zinc oxide coatings and platinum coatings were deposited on nanoporous alumina membranes by means of atomic layer deposition. PEGylated nanoporous alumina membranes were prepared by self-assembly of 1-mercaptoundec-11-yl hexa(ethylene glycol) on platinum-coated nanoporous alumina membranes. The pores of the PEGylated nanoporous alumina membranes remained free of fouling after exposure to human platelet-rich plasma; protein adsorption, fibrin networks and platelet aggregation were not observed on the coated membrane surface. Zinc oxide-coated nanoporous alumina membranes demonstrated activity against two waterborne pathogens, Escherichia coli and Staphylococcus aureus. The results of this work indicate that nanoporous alumina membranes may be modified using atomic layer deposition for use in a variety of medical and environmental health applications. PMID:20308114

Multichannel detection of ionic currents through two nanopores fabricated on integrated Si3N4 membranes.

PubMed

Yanagi, Itaru; Akahori, Rena; Aoki, Mayu; Harada, Kunio; Takeda, Ken-Ichi

2016-08-16

Integration of solid-state nanopores and multichannel detection of signals from each nanopore are effective measures for realizing high-throughput nanopore sensors. In the present study, we demonstrated fabrication of Si3N4 membrane arrays and the simultaneous measurement of ionic currents through two nanopores formed in two adjacent membranes. Membranes with thicknesses as low as 6.4 nm and small nanopores with diameters of less than 2 nm could be fabricated using the poly-Si sacrificial-layer process and multilevel pulse-voltage injection. Using the fabricated nanopore membranes, we successfully achieved simultaneous detection of clear ionic-current blockades when single-stranded short homopolymers (poly(dA)60) passed through two nanopores. In addition, we investigated the signal crosstalk and leakage current among separated chambers. When two nanopores were isolated on the front surface of the membrane, there was no signal crosstalk or leakage current between the chambers. However, when two nanopores were isolated on the backside of the Si substrate, signal crosstalk and leakage current were observed owing to high-capacitance coupling between the chambers and electrolysis of water on the surface of the Si substrate. The signal crosstalk and leakage current could be suppressed by oxidizing the exposed Si surface in the membrane chip. Finally, the observed ionic-current blockade when poly(dA)60 passed through the nanopore in the oxidized chip was approximately half of that observed in the non-oxidized chip.

Characteristic Features of Water Dynamics in Restricted Geometries Investigated with Quasi-Elastic Neutron Scattering

DOE PAGES

Osti, Naresh C.; Mamontov, Eugene; Ramirez-cuesta, A.; ...

2015-12-10

Understanding the molecular behavior of water in spatially restricted environments is important to better understanding its role in many biological, chemical and geological processes. Here we examine the translational diffusion of water confined to a variety of substrates, from flat surfaces to nanoporous media, in the context of a recently proposed universal scaling law (Chiavazzo 2014) [1]. Using over a dozen previous neutron scattering results, we test the validity of this law, evaluating separately the influence of the hydration amount, and the effects of the size and morphology of the confining medium. Additionally, we investigate the effects of changing instrumentmore » resolutions and fitting models on the applicability of this law. Finally, we perform quasi-elastic neutron scattering measurements on water confined inside nanoporous silica to further evaluate this predictive law, in the temperature range 250≤T≤290 K.« less

Recent advances in applications of nanomaterials for sample preparation.

PubMed

Xu, Linnan; Qi, Xiaoyue; Li, Xianjiang; Bai, Yu; Liu, Huwei

2016-01-01

Sample preparation is a key step for qualitative and quantitative analysis of trace analytes in complicated matrix. Along with the rapid development of nanotechnology in material science, numerous nanomaterials have been developed with particularly useful applications in analytical chemistry. Benefitting from their high specific areas, increased surface activities, and unprecedented physical/chemical properties, the potentials of nanomaterials for rapid and efficient sample preparation have been exploited extensively. In this review, recent progress of novel nanomaterials applied in sample preparation has been summarized and discussed. Both nanoparticles and nanoporous materials are evaluated for their unusual performance in sample preparation. Various compositions and functionalizations extended the applications of nanomaterials in sample preparations, and distinct size and shape selectivity was generated from the diversified pore structures of nanoporous materials. Such great variety make nanomaterials a kind of versatile tools in sample preparation for almost all categories of analytes. Copyright © 2015 Elsevier B.V. All rights reserved.

Quantifying similarity of pore-geometry in nanoporous materials

DOE PAGES

Lee, Yongjin; Barthel, Senja D.; Dłotko, Paweł; ...

2017-05-23

In most applications of nanoporous materials the pore structure is as important as the chemical composition as a determinant of performance. For example, one can alter performance in applications like carbon capture or methane storage by orders of magnitude by only modifying the pore structure. For these applications it is therefore important to identify the optimal pore geometry and use this information to find similar materials. But, the mathematical language and tools to identify materials with similar pore structures, but different composition, has been lacking. We develop a pore recognition approach to quantify similarity of pore structures and classify themmore » using topological data analysis. This then allows us to identify materials with similar pore geometries, and to screen for materials that are similar to given top-performing structures. Using methane storage as a case study, we also show that materials can be divided into topologically distinct classes requiring different optimization strategies.« less

Targeted drug delivery using genetically engineered diatom biosilica.

PubMed

Delalat, Bahman; Sheppard, Vonda C; Rasi Ghaemi, Soraya; Rao, Shasha; Prestidge, Clive A; McPhee, Gordon; Rogers, Mary-Louise; Donoghue, Jacqueline F; Pillay, Vinochani; Johns, Terrance G; Kröger, Nils; Voelcker, Nicolas H

2015-11-10

The ability to selectively kill cancerous cell populations while leaving healthy cells unaffected is a key goal in anticancer therapeutics. The use of nanoporous silica-based materials as drug-delivery vehicles has recently proven successful, yet production of these materials requires costly and toxic chemicals. Here we use diatom microalgae-derived nanoporous biosilica to deliver chemotherapeutic drugs to cancer cells. The diatom Thalassiosira pseudonana is genetically engineered to display an IgG-binding domain of protein G on the biosilica surface, enabling attachment of cell-targeting antibodies. Neuroblastoma and B-lymphoma cells are selectively targeted and killed by biosilica displaying specific antibodies sorbed with drug-loaded nanoparticles. Treatment with the same biosilica leads to tumour growth regression in a subcutaneous mouse xenograft model of neuroblastoma. These data indicate that genetically engineered biosilica frustules may be used as versatile 'backpacks' for the targeted delivery of poorly water-soluble anticancer drugs to tumour sites.

Investigation of nanoporous platinum thin films fabricated by reactive sputtering: Application as micro-SOFC electrode

NASA Astrophysics Data System (ADS)

Jung, WooChul; Kim, Jae Jin; Tuller, Harry L.

2015-02-01

Highly porous Pt thin films, with nano-scale porosity, were fabricated by reactive sputtering. The strategy involved deposition of thin film PtOx at room temperature, followed by the subsequent decomposition of the oxide by rapid heat treatment. The resulting films exhibited percolating Pt networks infiltrated with interconnected nanosized pores, critical for superior solid oxide fuel cell cathode performance. This approach is particularly attractive for micro-fabricated solid oxide fuel cells, since it enables fabrication of the entire cell stack (anode/electrolyte/cathode) within the sputtering chamber, without breaking vacuum. In this work, the morphological, crystallographic and chemical properties of the porous electrode were systematically varied by control of deposition conditions. Oxygen reduction reaction kinetics were investigated by means of electrochemical impedance spectroscopy, demonstrating the critical role of nano-pores in achieving satisfactory micro-SOFC cathode performance.

Rh6G released from solid and nanoporous SiO2 spheres prepared by sol-gel route

NASA Astrophysics Data System (ADS)

García-Macedo, J. A.; Francisco S., P.; Franco, A.

2015-10-01

Porous silica nanoparticles are considering good systems for drug cargo and liquid separation. In this work we studied the release of rhodamine 6G (Rh6G) from solid and porous silica nanoparticles. Solid and porous SiO2 spheres were prepared by sol-gel method. Nanoporous channels were produced by using a surfactant that was removed by chemical procedure. Rh6G was incorporated into the channels by impregnation. The hexagonal structure of the pores was detected by XRD and confirmed by HRTEM micrographs. Rh6G released from the particles by stirring them in water at controlled speed was studied as function of time by photoluminescence. Released ratio was faster in the solid nanoparticles than in the porous ones. In the last case, a second release mechanism was observed. It was related with rhodamine coming out from the porous.

DNA translocation through graphene nanopores.

PubMed

Merchant, Christopher A; Healy, Ken; Wanunu, Meni; Ray, Vishva; Peterman, Neil; Bartel, John; Fischbein, Michael D; Venta, Kimberly; Luo, Zhengtang; Johnson, A T Charlie; Drndić, Marija

2010-08-11

We report on DNA translocations through nanopores created in graphene membranes. Devices consist of 1-5 nm thick graphene membranes with electron-beam sculpted nanopores from 5 to 10 nm in diameter. Due to the thin nature of the graphene membranes, we observe larger blocked currents than for traditional solid-state nanopores. However, ionic current noise levels are several orders of magnitude larger than those for silicon nitride nanopores. These fluctuations are reduced with the atomic-layer deposition of 5 nm of titanium dioxide over the device. Unlike traditional solid-state nanopore materials that are insulating, graphene is an excellent electrical conductor. Use of graphene as a membrane material opens the door to a new class of nanopore devices in which electronic sensing and control are performed directly at the pore.

Label-free histamine detection with nanofluidic diodes through metal ion displacement mechanism.

PubMed

Ali, Mubarak; Ramirez, Patricio; Duznovic, Ivana; Nasir, Saima; Mafe, Salvador; Ensinger, Wolfgang

2017-02-01

We design and characterize a nanofluidic device for the label-free specific detection of histamine neurotransmitter based on a metal ion displacement mechanism. The sensor consists of an asymmetric polymer nanopore fabricated via ion track-etching technique. The nanopore sensor surface having metal-nitrilotriacetic (NTA-Ni 2+ ) chelates is obtained by covalent coupling of native carboxylic acid groups with N α ,N α -bis(carboxymethyl)-l-lysine (BCML), followed by exposure to Ni 2+ ion solution. The BCML immobilization and subsequent Ni 2+ ion complexation with NTA moieties change the surface charge concentration, which has a significant impact on the current-voltage (I-V) curve after chemical modification of the nanopore. The sensing mechanism is based on the displacement of the metal ion from the NTA-Ni 2+ chelates. When the modified pore is exposed to histamine solution, the Ni 2+ ion in NTA-Ni 2+ chelate recognizes histamine through a metal ion coordination displacement process and formation of stable Ni-histamine complexes, leading to the regeneration of metal-free NTA groups on the pore surface, as shown in the current-voltage characteristics. Nanomolar concentrations of the histamine in the working electrolyte can be detected. On the contrary, other neurotransmitters such as glycine, serotonin, gamma-aminobutyric acid, and dopamine do not provoke significant changes in the nanopore electronic signal due to their inability to displace the metal ion and form a stable complex with Ni 2+ ion. The nanofluidic sensor exhibits high sensitivity, specificity and reusability towards histamine detection and can then be used to monitor the concentration of biological important neurotransmitters. Copyright © 2016 Elsevier B.V. All rights reserved.

Structure-dependent water transport across nanopores of carbon nanotubes: toward selective gating upon temperature regulation.

PubMed

Zhao, Kuiwen; Wu, Huiying

2015-04-28

Determining water structure in nanopores and its influence on water transport behaviour is of great importance for understanding and regulating the transport across nanopores. Here we report an ultrafast-slow flow transition phenomenon for water transport across nanopores of carbon nanotubes owing to the change in water structure in nanopores induced by temperature. By performing extensive molecular dynamics simulations, we show the dependence of water transport behaviours on water structures. Our results indicate that owing to the change in water structure in nanopores, water flux across nanopores with certain pore sizes decreases sharply (nearly 3 orders of magnitude) with the decreasing temperature. This phenomenon is very sensitive to the pore size. The threshold temperatures for the occurrence of the ultrafast-slow flow transition for water transport are also determined for various pore sizes. These findings suggest a novel protocol for selective gating of water and proton conduction across nanopores and temperature-controlled drug release.

Nanopore-CMOS Interfaces for DNA Sequencing

PubMed Central

Magierowski, Sebastian; Huang, Yiyun; Wang, Chengjie; Ghafar-Zadeh, Ebrahim

2016-01-01

DNA sequencers based on nanopore sensors present an opportunity for a significant break from the template-based incumbents of the last forty years. Key advantages ushered by nanopore technology include a simplified chemistry and the ability to interface to CMOS technology. The latter opportunity offers substantial promise for improvement in sequencing speed, size and cost. This paper reviews existing and emerging means of interfacing nanopores to CMOS technology with an emphasis on massively-arrayed structures. It presents this in the context of incumbent DNA sequencing techniques, reviews and quantifies nanopore characteristics and models and presents CMOS circuit methods for the amplification of low-current nanopore signals in such interfaces. PMID:27509529

Nanopore-CMOS Interfaces for DNA Sequencing.

PubMed

Magierowski, Sebastian; Huang, Yiyun; Wang, Chengjie; Ghafar-Zadeh, Ebrahim

2016-08-06

DNA sequencers based on nanopore sensors present an opportunity for a significant break from the template-based incumbents of the last forty years. Key advantages ushered by nanopore technology include a simplified chemistry and the ability to interface to CMOS technology. The latter opportunity offers substantial promise for improvement in sequencing speed, size and cost. This paper reviews existing and emerging means of interfacing nanopores to CMOS technology with an emphasis on massively-arrayed structures. It presents this in the context of incumbent DNA sequencing techniques, reviews and quantifies nanopore characteristics and models and presents CMOS circuit methods for the amplification of low-current nanopore signals in such interfaces.

Membranes with functionalized carbon nanotube pores for selective transport

DOEpatents

Bakajin, Olgica; Noy, Aleksandr; Fornasiero, Francesco; Park, Hyung Gyu; Holt, Jason K; Kim, Sangil

2015-01-27

Provided herein composition and methods for nanoporous membranes comprising single walled, double walled, or multi-walled carbon nanotubes embedded in a matrix material. Average pore size of the carbon nanotube can be 6 nm or less. These membranes are a robust platform for the study of confined molecular transport, with applications in liquid and gas separations and chemical sensing including desalination, dialysis, and fabric formation.

Nanochannel Device with Embedded Nanopore: a New Approach for Single-Molecule DNA Analysis and Manipulation

NASA Astrophysics Data System (ADS)

Zhang, Yuning; Reisner, Walter

2013-03-01

Nanopore and nanochannel based devices are robust methods for biomolecular sensing and single DNA manipulation. Nanopore-based DNA sensing has attractive features that make it a leading candidate as a single-molecule DNA sequencing technology. Nanochannel based extension of DNA, combined with enzymatic or denaturation-based barcoding schemes, is already a powerful approach for genome analysis. We believe that there is revolutionary potential in devices that combine nanochannels with embedded pore detectors. In particular, due to the fast translocation of a DNA molecule through a standard nanopore configuration, there is an unfavorable trade-off between signal and sequence resolution. With a combined nanochannel-nanopore device, based on embedding a pore inside a nanochannel, we can in principle gain independent control over both DNA translocation speed and sensing signal, solving the key draw-back of the standard nanopore configuration. We demonstrate that we can optically detect successful translocation of DNA from the nanochannel out through the nanopore, a possible method to 'select' a given barcode for further analysis. In particular, we show that in equilibrium DNA will not escape through an embedded sub-persistence length nanopore, suggesting that the pore could be used as a nanoscale window through which to interrogate a nanochannel extended DNA molecule. Furthermore, electrical measurements through the nanopore are performed, indicating that DNA sensing is feasible using the nanochannel-nanopore device.

Optofluidic devices with integrated solid-state nanopores

PubMed Central

Hawkins, Aaron R.; Schmidt, Holger

2016-01-01

This review (with 90 refs.) covers the state of the art in optofluidic devices with integrated solid-state nanopores for use in detection and sensing. Following an introduction into principles of optofluidics and solid-state nanopore technology, we discuss features of solid-state nanopore based assays using optofluidics. This includes the incorporation of solid-state nanopores into optofluidic platforms based on liquid-core anti-resonant reflecting optical waveguides (ARROWs), methods for their fabrication, aspects of single particle detection and particle manipulation. We then describe the new functionalities provided by solid-state nanopores integrated into optofluidic chips, in particular acting as smart gates for correlated electro-optical detection and discrimination of nanoparticles. This enables the identification of viruses and λ-DNA, particle trajectory simulations, enhancing sensitivity by tuning the shape of nanopores. The review concludes with a summary and an outlook. PMID:27046940

In vitro proliferation and osteogenic differentiation of mesenchymal stem cells on nanoporous alumina

PubMed Central

Song, Yuanhui; Ju, Yang; Song, Guanbin; Morita, Yasuyuki

2013-01-01

Cell adhesion, migration, and proliferation are significantly affected by the surface topography of the substrates on which the cells are cultured. Alumina is one of the most popular implant materials used in orthopedics, but few data are available concerning the cellular responses of mesenchymal stem cells (MSCs) grown on nanoporous structures. MSCs were cultured on smooth alumina substrates and nanoporous alumina substrates to investigate the interaction between surface topographies of nanoporous alumina and cellular behavior. Nanoporous alumina substrates with pore sizes of 20 nm and 100 nm were used to evaluate the effect of pore size on MSCs as measured by proliferation, morphology, expression of integrin β1, and osteogenic differentiation. An MTT assay was used to measure cell viability of MSCs on different substrates, and determined that cell viability decreased with increasing pore size. Scanning electron microscopy was used to investigate the effect of pore size on cell morphology. Extremely elongated cells and prominent cell membrane protrusions were observed in cells cultured on alumina with the larger pore size. The expression of integrin β1 was enhanced in MSCs cultured on porous alumina, revealing that porous alumina substrates were more favorable for cell growth than smooth alumina substrates. Higher levels of osteoblastic differentiation markers such as alkaline phosphatase, osteocalcin, and mineralization were detected in cells cultured on alumina with 100 nm pores compared with cells cultured on alumina with either 20 nm pores or smooth alumina. This work demonstrates that cellular behavior is affected by variation in pore size, providing new insight into the potential application of this novel biocompatible material for the developing field of tissue engineering. PMID:23935364

A universal model for nanoporous carbon supercapacitors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Jingsong; Sumpter, Bobby G; Meunier, Vincent

2009-01-01

Supercapacitors based on nanoporous carbon materials, commonly called electric double-layer capacitors (EDLCs), are emerging as a novel type of energy-storage device with the potential to substitute batteries in applications that require high power densities. Nanoporous carbon supercapacitors are generally viewed as a parallel-plate capacitor since supercapacitors store energy by charge separation in an electric double layer formed at the electrode/electrolyte interface. The EDLC model has been used to characterize the energy storage of supercapacitors for decades. We comment in this chapter on the shortcomings of the EDLC model when applied to nanoporous carbon supercapacitors. In response to the latest experimentalmore » breakthrough in nanoporous carbon supercapacitors, we have proposed a heuristic model that takes pore curvature into account as a replacement for the EDLC model. When the pore size is in the mesopore regime (2 50 nm), electrolyte counterions enter mesoporous carbons and approach the pore wall to form an electric double-cylinder capacitor (EDCC); in the micropore regime (< 2 nm), solvated/desolvated counterions line up along the pore axis to form an electric wire-in-cylinder capacitor (EWCC). In the macropore regime (> 50 nm), where pores are large enough so that pore curvature is no longer significant, the EDCC model can be reduced to the EDLC model. With the backing of experimental data and quantum density functional theory calculations, we have shown that the EDCC/EWCC model is universal for carbon supercapacitors with diverse carbon materials and electrolytes. The strengths and limitations of this new model are discussed. The new model allows the supercapacitor properties to be correlated with pore size, specific surface area, Debye length, electrolyte concentration, dielectric constant, and solute ion size, and may lend support to the systematic optimization of the properties of carbon supercapacitors through experiments.« less

Solid-state nanopores of controlled geometry fabricated in a transmission electron microscope

NASA Astrophysics Data System (ADS)

Qian, Hui; Egerton, Ray F.

2017-11-01

Energy-filtered transmission electron microscopy and electron tomography were applied to in situ studies of the formation, shape, and diameter of nanopores formed in a silicon nitride membrane in a transmission electron microscope. The nanopore geometry was observed in three dimensions by electron tomography. Drilling conditions, such as probe current, beam convergence angle, and probe position, affect the formation rate and the geometry of the pores. With a beam convergence semi-angle of α = 22 mrad, a conical shaped nanopore is formed but at α = 45 mrad, double-cone (hourglass-shaped) nanopores were produced. Nanopores with an effective diameter between 10 nm and 1.8 nm were fabricated by controlling the drilling time.

Storage and recovery of methane-ethane mixtures in single shale pores

NASA Astrophysics Data System (ADS)

Wu, Haiyi; Qiao, Rui

2017-11-01

Natural gas production from shale formations has received extensive attention recently. While great progress has been made in understanding the adsorption and transport of single-component gas inside shales' nanopores, the adsorption and transport of multicomponent shale gas under reservoir conditions (CH4 and C2H6 mixture) has only begun to be studied. In this work, we use molecular simulations to compute the storage of CH4 and C2H6 mixtures in single nanopores and their subsequent recovery. We show that surface adsorption contributes greatly to the storage of CH4 and C2H6 inside the pores and C2H6 is enriched over CH4. The enrichment of C2H6 is enhanced as the pore is narrowed, but is weakened as the pressure increases. We show that the recovery of gas mixtures from the nanopores approximately follows the diffusive scaling law. The ratio of the production rates of C2H6 and CH4 is close to their initial mole ratio inside the pore despite that the mobility of pure C2H6 is much smaller than that of pure CH4 inside the pores. By using scale analysis, we show that the strong coupling between the transport of CH4 and C2H6 is responsible for the effective recovery of C2H6 from the nanopores.

Recent patents of nanopore DNA sequencing technology: progress and challenges.

PubMed

Zhou, Jianfeng; Xu, Bingqian

2010-11-01

DNA sequencing techniques witnessed fast development in the last decades, primarily driven by the Human Genome Project. Among the proposed new techniques, Nanopore was considered as a suitable candidate for the single DNA sequencing with ultrahigh speed and very low cost. Several fabrication and modification techniques have been developed to produce robust and well-defined nanopore devices. Many efforts have also been done to apply nanopore to analyze the properties of DNA molecules. By comparing with traditional sequencing techniques, nanopore has demonstrated its distinctive superiorities in main practical issues, such as sample preparation, sequencing speed, cost-effective and read-length. Although challenges still remain, recent researches in improving the capabilities of nanopore have shed a light to achieve its ultimate goal: Sequence individual DNA strand at single nucleotide level. This patent review briefly highlights recent developments and technological achievements for DNA analysis and sequencing at single molecule level, focusing on nanopore based methods.

Single nanopore transport of synthetic and biological polyelectrolytes in three-dimensional hybrid microfluidic/nanofluidic devices

DOE PAGES

King, Travis L.; Gatimu, Enid N.; Bohn, Paul W.

2009-01-02

This paper presents a study of electrokinetic transport in single nanopores integrated into vertically-stacked three-dimensional hybrid microfluidic/nanofluidic structures. In these devices single nanopores, created by focused ion beam (FIB) milling in thin polymer films, provide fluidic connection between two vertically separated, perpendicular microfluidic channels. Experiments address both systems in which the nanoporous membrane is composed of the same (homojunction) or different (heterojunction) polymer as the microfluidic channels. These devices are then used to study the electrokinetic transport properties of synthetic (i.e., polystyrene sulfonate and polyallylamine) and biological (i.e.,DNA) polyelectrolytes across these nanopores. Single nanopore transport of polyelectrolytes across these nanoporesmore » using both electrical current measurements and confocal microscopy. Both optical and electrical measurements indicate that electroosmotic transport is predominant over electrophoresis in single nanopores with d > 180 nm, consistent with results obtained under similar conditions for nanocapillary array membranes.« less

Na⁺ and K⁺ ion selectivity by size-controlled biomimetic graphene nanopores.

PubMed

Kang, Yu; Zhang, Zhisen; Shi, Hui; Zhang, Junqiao; Liang, Lijun; Wang, Qi; Ågren, Hans; Tu, Yaoquan

2014-09-21

Because biological ionic channels play a key role in cellular transport phenomena, they have attracted extensive research interest for the design of biomimetic nanopores with high permeability and selectivity in a variety of technical applications. Inspired by the structure of K(+) channel proteins, we designed a series of oxygen doped graphene nanopores of different sizes by molecular dynamics simulations to discriminate between K(+) and Na(+) channel transport. The results from free energy calculations indicate that the ion selectivity of such biomimetic graphene nanopores can be simply controlled by the size of the nanopore; compared to K(+), the smaller radius of Na(+) leads to a significantly higher free energy barrier in the nanopore of a certain size. Our results suggest that graphene nanopores with a distance of about 3.9 Å between two neighboring oxygen atoms could constitute a promising candidate to obtain excellent ion selectivity for Na(+) and K(+) ions.

Alumina plate containing photosystem I reaction center complex oriented inside plate-penetrating silica nanopores.

PubMed

Kamidaki, Chihiro; Kondo, Toru; Noji, Tomoyasu; Itoh, Tetsuji; Yamaguchi, Akira; Itoh, Shigeru

2013-08-22

The photosynthetic photosystem I reaction center complex (PSI-RC), which has a molecular diameter of 21 nm with 100 pigments, was incorporated into silica nanopores with a 100-nm diameter that penetrates an alumina plate of 60-μm thickness to make up an inorganic-biological hybrid photocell. PSI-RCs, purified from a thermophilic cyanobacterium, were stable inside the nanopores and rapidly photoreduced a mediator dye methyl viologen. The reduced dye was more stable inside nanopores suggesting the decrease of dissolved oxygen. The analysis by a cryogenic electron spin paramagnetic resonance indicated the oriented arrangement of RCs inside the 100-nm nanopores, with their surface parallel to the silica wall and perpendicular to the plane of the alumina plate. PSI RC complex in the semicrystalline orientation inside silica nanopores can be a new type of light energy conversion unit to supply strong reducing power selectively to other molecules inside or outside nanopores.

In situ heavy ion irradiation studies of nanopore shrinkage and enhanced radiation tolerance of nanoporous Au

DOE PAGES

Li, Jin; Fan, Cuncai; Ding, Jie; ...

2017-01-03

High energy particle radiations induce severe microstructural damage in metallic materials. Nanoporous materials with a giant surface-to-volume ratio may alleviate radiation damage in irradiated metallic materials as free surface are defect sinks. We show, by using in situ Kr ion irradiation in a transmission electron microscope at room temperature, that nanoporous Au indeed has significantly improved radiation tolerance comparing with coarse-grained, fully dense Au. In situ studies show that nanopores can absorb and eliminate a large number of radiation-induced defect clusters. Meanwhile, nanopores shrink (self-heal) during radiation, and their shrinkage rate is pore size dependent. Furthermore, the in situ studiesmore » show dose-rate-dependent diffusivity of defect clusters. Our study sheds light on the design of radiation-tolerant nanoporous metallic materials for advanced nuclear reactor applications.« less

Highly active thermally stable nanoporous gold catalyst

DOE Office of Scientific and Technical Information (OSTI.GOV)

Biener, Juergen; Wittstock, Arne; Biener, Monika M.

In one embodiment, a system includes a nanoporous gold structure and a plurality of oxide particles deposited on the nanoporous gold structure; the oxide particles are characterized by a crystalline phase. In another embodiment, a method includes depositing oxide nanoparticles on a nanoporous gold support to form an active structure and functionalizing the deposited oxide nanoparticles.

Development of a 3D origami multiplex electrochemical immunodevice using a nanoporous silver-paper electrode and metal ion functionalized nanoporous gold-chitosan.

PubMed

Li, Weiping; Li, Long; Li, Meng; Yu, Jinghua; Ge, Shenguang; Yan, Mei; Song, Xianrang

2013-10-25

A simple and sensitive 3D microfluidic origami multiplex electrochemical immunodevice was developed for the first time using a novel nanoporous silver modified paper working electrode as a sensor platform and different metal ion functionalized nanoporous gold-chitosan as a tracer.

Basic evaluation of typical nanoporous silica nanoparticles in being drug carrier: Structure, wettability and hemolysis.

PubMed

Li, Jing; Guo, Yingyu

2017-04-01

Herein, the present work devoted to study the basic capacity of nanoporous silica nanoparticles in being drug carrier that covered structure, wettability and hemolysis so as to provide crucial evaluation. Typical nanoporous silica nanoparticles that consist of nanoporous silica nanoparticles (NSN), amino modified nanoporous silica nanoparticles (amino-NSN), carboxyl modified nanoporous silica nanoparticles (carboxyl-NSN) and hierachical nanoporous silica nanoparticles (hierachical-NSN) were studied. The results showed that their wettability and hemolysis were closely related to structure and surface modification. Basically, wettability became stronger as the amount of OH on the surface of NSN was higher. Both large nanopores and surface modification can reduce the wettability of NSN. Furthermore, NSN series were safe to be used when they circulated into the blood in low concentration, while if high concentration can not be avoided during administration, high porosity or amino modification of NSN were safer to be considered. It is believed that the basic evaluation of NSN can make contribution in providing scientific instruction for designing drug loaded NSN systems. Copyright © 2016 Elsevier B.V. All rights reserved.

Precise fabrication of a 5 nm graphene nanopore with a helium ion microscope for biomolecule detection

NASA Astrophysics Data System (ADS)

Deng, Yunsheng; Huang, Qimeng; Zhao, Yue; Zhou, Daming; Ying, Cuifeng; Wang, Deqiang

2017-01-01

We report a scalable method to fabricate high-quality graphene nanopores for biomolecule detection using a helium ion microscope (HIM). HIM milling shows promising capabilities for precisely controlling the size and shape, and may allow for the potential production of nanopores at wafer scale. Nanopores could be fabricated at different sizes ranging from 5 to 30 nm in diameter in few minutes. Compared with the current solid-state nanopore fabrication techniques, e.g. transmission electron microscopy, HIM is fast. Furthermore, we investigated the exposure-time dependence of graphene nanopore formation: the rate of pore expansion did not follow a simple linear relationship with exposure time, but a fast expansion rate at short exposure time and a slow rate at long exposure time. In addition, we performed biomolecule detection with our patterned graphene nanopore. The ionic current signals induced by 20-base single-stranded DNA homopolymers could be used as a basis for homopolymer differentiation. However, the charge interaction of homopolymer chains with graphene nanopores, and the conformations of homopolymer chains need to be further considered to improve the accuracy of discrimination.

Measurement of DNA translocation dynamics in a solid-state nanopore at 100-ns temporal resolution

PubMed Central

Shekar, Siddharth; Niedzwiecki, David J.; Chien, Chen-Chi; Ong, Peijie; Fleischer, Daniel A.; Lin, Jianxun; Rosenstein, Jacob K.; Drndic, Marija; Shepard, Kenneth L.

2017-01-01

Despite the potential for nanopores to be a platform for high-bandwidth study of single-molecule systems, ionic current measurements through nanopores have been limited in their temporal resolution by noise arising from poorly optimized measurement electronics and large parasitic capacitances in the nanopore membranes. Here, we present a complementary metal-oxide-semiconductor (CMOS) nanopore (CNP) amplifier capable of low noise recordings at an unprecedented 10 MHz bandwidth. When integrated with state-of-the-art solid-state nanopores in silicon nitride membranes, we achieve an SNR of greater than 10 for ssDNA translocations at a measurement bandwidth of 5 MHz, which represents the fastest ion current recordings through nanopores reported to date. We observe transient features in ssDNA translocation events that are as short as 200 ns, which are hidden even at bandwidths as high as 1 MHz. These features offer further insights into the translocation kinetics of molecules entering and exiting the pore. This platform highlights the advantages of high-bandwidth translocation measurements made possible by integrating nanopores and custom-designed electronics. PMID:27332998

Nanofluidic Device with Embedded Nanopore

NASA Astrophysics Data System (ADS)

Zhang, Yuning; Reisner, Walter

2014-03-01

Nanofluidic based devices are robust methods for biomolecular sensing and single DNA manipulation. Nanopore-based DNA sensing has attractive features that make it a leading candidate as a single-molecule DNA sequencing technology. Nanochannel based extension of DNA, combined with enzymatic or denaturation-based barcoding schemes, is already a powerful approach for genome analysis. We believe that there is revolutionary potential in devices that combine nanochannels with nanpore detectors. In particular, due to the fast translocation of a DNA molecule through a standard nanopore configuration, there is an unfavorable trade-off between signal and sequence resolution. With a combined nanochannel-nanopore device, based on embedding a nanopore inside a nanochannel, we can in principle gain independent control over both DNA translocation speed and sensing signal, solving the key draw-back of the standard nanopore configuration. We demonstrate that we can detect - using fluorescent microscopy - successful translocation of DNA from the nanochannel out through the nanopore, a possible method to 'select' a given barcode for further analysis. We also show that in equilibrium DNA will not escape through an embedded sub-persistence length nanopore until a certain voltage bias is added.

3-D simulation of nanopore structure for DNA sequencing.

PubMed

Park, Jun-Mo; Pak, Y Eugene; Chun, Honggu; Lee, Jong-Ho

2012-07-01

In this paper, we propose a method for simulating nanopore structure by using conventional 3-D simulation tool to mimic the I-V behavior of the nanopore structure. In the simulation, we use lightly doped silicon for ionic solution where some parameters like electron affinity and dielectric constant are fitted to consider the ionic solution. By using this method, we can simulate the I-V behavior of nanopore structure depending on the location and the size of the sphere shaped silicon oxide which is considered to be an indicator of a DNA base. In addition, we simulate an Ionic Field Effect Transistor (IFET) which has basically the nanopore structure, and show that the simulated curves follow sufficiently the I-V behavior of the measurement data. Therefore, we think it is reasonable to apply parameter modeling mentioned above to simulate nanopore structure. The key idea is to modify electron affinity of silicon which is used to mimic the KCl solution to avoid band bending and depletion inside the nanopore. We could efficiently utilize conventional 3-D simulation tool to simulate the I-V behavior of nanopore structures.

Translocation of a Polymer Chain across a Nanopore: A Brownian Dynamics Simulation Study

NASA Technical Reports Server (NTRS)

Tian, Pu; Smith, Grant D.

2003-01-01

We carried out Brownian dynamics simulation studies of the translocation of single polymer chains across a nanosized pore under the driving of an applied field (chemical potential gradient). The translocation process can be either dominated by the entropic barrier resulted from restricted motion of flexible polymer chains or by applied forces (or chemical gradient across the wall), we focused on the latter case in our studies. Calculation of radius of gyrations at the two opposite sides of the wall shows that the polymer chains are not in equilibrium during the translocation process. Despite this fact, our results show that the one-dimensional diffusion and the nucleation model provide an excellent description of the dependence of average translocation time on the chemical potential gradients, the polymer chain length and the solvent viscosity. In good agreement with experimental results and theoretical predictions, the translocation time distribution of our simple model shows strong non-Gaussian characteristics. It is observed that even for this simple tubelike pore geometry, more than one peak of translocation time distribution can be generated for proper pore diameter and applied field strengths. Both repulsive Weeks-Chandler-Anderson and attractive Lennard-Jones polymer-nanopore interaction were studied, attraction facilitates the translocation process by shortening the total translocation time and dramatically improve the capturing of polymer chain. The width of the translocation time distribution was found to decrease with increasing temperature, increasing field strength, and decreasing pore diameter.

Ion selection of charge-modified large nanopores in a graphene sheet

NASA Astrophysics Data System (ADS)

Zhao, Shijun; Xue, Jianming; Kang, Wei

2013-09-01

Water desalination becomes an increasingly important approach for clean water supply to meet the rapidly growing demand of population boost, industrialization, and urbanization. The main challenge in current desalination technologies lies in the reduction of energy consumption and economic costs. Here, we propose to use charged nanopores drilled in a graphene sheet as ion exchange membranes to promote the efficiency and capacity of desalination systems. Using molecular dynamics simulations, we investigate the selective ion transport behavior of electric-field-driven KCl electrolyte solution through charge modified graphene nanopores. Our results reveal that the presence of negative charges at the edge of graphene nanopore can remarkably impede the passage of Cl- while enhance the transport of K+, which is an indication of ion selectivity for electrolytes. We further demonstrate that this selectivity is dependent on the pore size and total charge number assigned at the nanopore edge. By adjusting the nanopore diameter and electric charge on the graphene nanopore, a nearly complete rejection of Cl- can be realized. The electrical resistance of nanoporous graphene, which is a key parameter to evaluate the performance of ion exchange membranes, is found two orders of magnitude lower than commercially used membranes. Our results thus suggest that graphene nanopores are promising candidates to be used in electrodialysis technology for water desalinations with a high permselectivity.

Micropatterning of a nanoporous alumina membrane with poly(ethylene glycol) hydrogel to create cellular micropatterns on nanotopographic substrates.

PubMed

Lee, Hyun Jong; Kim, Dae Nyun; Park, Saemi; Lee, Yeol; Koh, Won-Gun

2011-03-01

In this paper, we describe a simple method for fabricating micropatterned nanoporous substrates that are capable of controlling the spatial positioning of mammalian cells. Micropatterned substrates were prepared by fabricating poly(ethylene glycol) (PEG) hydrogel microstructures on alumina membranes with 200 nm nanopores using photolithography. Because hydrogel precursor solution could infiltrate and become crosslinked within the nanopores, the resultant hydrogel micropatterns were firmly anchored on the substrate without the use of adhesion-promoting monolayers, thereby allow tailoring of the surface properties of unpatterned nanoporous areas. For mammalian cell patterning, arrays of microwells of different dimensions were fabricated. These microwells were composed of hydrophilic PEG hydrogel walls surrounding nanoporous bottoms that were modified with cell-adhesive Arg-Gly-Asp (RGD) peptides. Because the PEG hydrogel was non-adhesive towards proteins and cells, cells adhered selectively and remained viable within the RGD-modified nanoporous regions, thereby creating cellular micropatterns. Although the morphology of cell clusters and the number of cells inside one microwell were dependent on the lateral dimension of the microwells, adhered cells that were in direct contact with nanopores were able to penetrate into the nanopores by small extensions (filopodia) for all the different sizes of microwells evaluated. Copyright © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Asymmetric Supercapacitors Using 3D Nanoporous Carbon and Cobalt Oxide Electrodes Synthesized from a Single Metal-Organic Framework.

PubMed

Salunkhe, Rahul R; Tang, Jing; Kamachi, Yuichiro; Nakato, Teruyuki; Kim, Jung Ho; Yamauchi, Yusuke

2015-06-23

Nanoporous carbon and nanoporous cobalt oxide (Co3O4) materials have been selectively prepared from a single metal-organic framework (MOF) (zeolitic imidazolate framework, ZIF-67) by optimizing the annealing conditions. The resulting ZIF-derived carbon possesses highly graphitic walls and a high specific surface area of 350 m(2)·g(-1), while the resulting ZIF-derived nanoporous Co3O4 possesses a high specific surface area of 148 m(2)·g(-1) with much less carbon content (1.7 at%). When nanoporous carbon and nanoporous Co3O4 were tested as electrode materials for supercapacitor application, they showed high capacitance values (272 and 504 F·g(-1), respectively, at a scan rate of 5 mV·s(-1)). To further demonstrate the advantages of our ZIF-derived nanoporous materials, symmetric (SSCs) and asymmetric supercapacitors (ASCs) were also fabricated using nanoporous carbon and nanoporous Co3O4 electrodes. Improved capacitance performance was successfully realized for the ASC (Co3O4//carbon), better than those of the SSCs based on nanoporous carbon and nanoporous Co3O4 materials (i.e., carbon//carbon and Co3O4//Co3O4). The developed ASC with an optimal mass loading can be operated within a wide potential window of 0.0-1.6 V, which leads to a high specific energy of 36 W·h·kg(-1). More interestingly, this ASC also exhibits excellent rate capability (with the highest specific power of 8000 W·kg(-1) at a specific energy of 15 W·h·kg(-1)) combined with long-term stability up to 2000 cycles.

Improved Analysis of Nanopore Sequence Data and Scanning Nanopore Techniques

NASA Astrophysics Data System (ADS)

Szalay, Tamas

The field of nanopore research has been driven by the need to inexpensively and rapidly sequence DNA. In order to help realize this goal, this thesis describes the PoreSeq algorithm that identifies and corrects errors in real-world nanopore sequencing data and improves the accuracy of de novo genome assembly with increasing coverage depth. The approach relies on modeling the possible sources of uncertainty that occur as DNA advances through the nanopore and then using this model to find the sequence that best explains multiple reads of the same region of DNA. PoreSeq increases nanopore sequencing read accuracy of M13 bacteriophage DNA from 85% to 99% at 100X coverage. We also use the algorithm to assemble E. coli with 30X coverage and the lambda genome at a range of coverages from 3X to 50X. Additionally, we classify sequence variants at an order of magnitude lower coverage than is possible with existing methods. This thesis also reports preliminary progress towards controlling the motion of DNA using two nanopores instead of one. The speed at which the DNA travels through the nanopore needs to be carefully controlled to facilitate the detection of individual bases. A second nanopore in close proximity to the first could be used to slow or stop the motion of the DNA in order to enable a more accurate readout. The fabrication process for a new pyramidal nanopore geometry was developed in order to facilitate the positioning of the nanopores. This thesis demonstrates that two of them can be placed close enough to interact with a single molecule of DNA, which is a prerequisite for being able to use the driving force of the pores to exert fine control over the motion of the DNA. Another strategy for reading the DNA is to trap it completely with one pore and to move the second nanopore instead. To that end, this thesis also shows that a single strand of immobilized DNA can be captured in a scanning nanopore and examined for a full hour, with data from many scans at many different voltages obtained in order to detect a bound protein placed partway along the molecule.

Engineering the entropy-driven free-energy landscape of a dynamic nanoporous protein assembly.

PubMed

Alberstein, Robert; Suzuki, Yuta; Paesani, Francesco; Tezcan, F Akif

2018-04-30

De novo design and construction of stimuli-responsive protein assemblies that predictably switch between discrete conformational states remains an essential but highly challenging goal in biomolecular design. We previously reported synthetic, two-dimensional protein lattices self-assembled via disulfide bonding interactions, which endows them with a unique capacity to undergo coherent conformational changes without losing crystalline order. Here, we carried out all-atom molecular dynamics simulations to map the free-energy landscape of these lattices, validated this landscape through extensive structural characterization by electron microscopy and established that it is predominantly governed by solvent reorganization entropy. Subsequent redesign of the protein surface with conditionally repulsive electrostatic interactions enabled us to predictably perturb the free-energy landscape and obtain a new protein lattice whose conformational dynamics can be chemically and mechanically toggled between three different states with varying porosities and molecular densities.

Immobilization of glucose oxidase into a nanoporous TiO₂ film layered on metallophthalocyanine modified vertically-aligned carbon nanotubes for efficient direct electron transfer.

PubMed

Cui, Hui-Fang; Zhang, Kuan; Zhang, Yong-Fang; Sun, Yu-Long; Wang, Jia; Zhang, Wei-De; Luong, John H T

2013-08-15

Glucose oxidase (GOD) was adsorbed into a nanoporous TiO₂ film layered on the surface of an iron phthalocyanine (FePc) vertically-aligned carbon nanotube (CNT) modified electrode. A Nafion film was then dropcast on the electrode's surface to improve operational and storage stabilities of the GOD-based electrode. Scanning electron microscopy (SEM) micrographs revealed the formation of FePc and nanoporous TiO₂ nanoparticles along the sidewall and the tip of CNTs. Cyclic voltammograms of the GOD electrode in neutral PBS exhibited a pair of well-defined redox peaks, attesting the direct electron transfer of GOD (FAD/FADH₂) with the underlying electrode. The potential of glucose electro-oxidation under nitrogen was ∼+0.12 V with an oxidation current density of 65.3 μA cm(-2) at +0.77 V. Voltammetric and amperometric responses were virtually unaffected by oxygen, illustrating an efficient and fast direct electron transfer. The modification of the CNT surface with FePc resulted in a biosensor with remarkable detection sensitivity with an oxygen-independent bioelectrocatalysis. In deaerated PBS, the biosensor displayed average response time of 12 s, linearity from 50 μM to 4 mM, and a detection limit of 30 μM (S/N=3) for glucose. Copyright © 2013 Elsevier B.V. All rights reserved.

Ultrathin NiCo2O4 nanowalls supported on a 3D nanoporous gold coated needle for non-enzymatic amperometric sensing of glucose.

PubMed

Li, Weiwei; Qi, Hui; Wang, Baogang; Wang, Qiyu; Wei, Shuting; Zhang, Xiaolin; Wang, Ying; Zhang, Lei; Cui, Xiaoqiang

2018-01-24

A disposable needle-type of hybrid electrode was prepared from a core of stainless steel needle whose surface was modified with a 3D nanoporous gold/NiCo 2 O 4 nanowall hybrid structure for electrochemical non-enzymatic glucose detection. This hybrid electrode, best operated at 0.45 V (vs. SCE) in solutions of pH 13 has a linear response in the 0.01 to 21 mM glucose concentration range, a response time of <1 s, and a 1 μM detection limit (at an S/N ratio of 3). The remarkable enhancement compared to the solid gold/NiCo 2 O 4 and stainless steel/NiCo 2 O 4 hybrid electrodes in electrochemical performance is assumed to originate from the good electrical conductivity and large surface area of the hybrid electrode, which enhance the transport of mass and charge during electrochemical reactions. This biosensor was also applied to real sample analysis with little interferences. The electrode is disposable and considered to be a promising tool for non-enzymatic sensing of glucose in a variety of practical situations. Graphical abstract Ultrathin NiCo 2 O 4 nanowalls supported on nanoporous gold that is coated on a stainless steel needle was fabricated for sensitive non-enzymatic amperometric sensing of glucose.

WS2 nanopores for molecule analysis

NASA Astrophysics Data System (ADS)

Danda, Gopinath; Masih Das, Paul; Chou, Yung-Chien; Mlack, Jerome; Naylor, Carl; Perea-Lopez, Nestor; Lin, Zhong; Fulton, Laura Beth; Terrones, Mauricio; Johnson, A. T. Charlie; Drndic, Marija

Atomically thin 2D materials like graphene and transition metal dichalcogenides (TMDs) are interesting as membranes in solid state nanopore sensors for DNA analysis as they may facilitate single base resolution sequencing. These materials also exhibit unique optical and electronic properties which may be exploited to enhance the functionality of nanopore sensors. Here, we report WS2 nanopores, fabricated using a focused TEM beam. We also report their controlled laser-induced expansion in ionic solution. This study demonstrates the possibility of dynamic control of nanopore characteristics optically. NIH Grant R21HG007856, NSF EFRI-1542707.

Fabricatable nanopore sensors with an atomic thickness

NASA Astrophysics Data System (ADS)

Luan, Binquan; Bai, Jingwei; Stolovitzky, Gustavo

2013-10-01

When analyzing biological molecules (such as DNA and proteins) transported through a nanopore sensor, the pore length limits both the sensitivity and the spatial resolution. Atomically thin as a graphene nanopore is, it is difficult to make graphene pores and the scalable-fabrication of those pores has not yet been possible. We theoretically studied a type of atomically thin nanopores that are formed by intersection of two perpendicular nano-slits. Based on theoretical analyses, we demonstrate that slit nanopores behave similarly to graphene pores and can be manufactured at a wafer scale.

Nanopores formed by DNA origami: a review.

PubMed

Bell, Nicholas A W; Keyser, Ulrich F

2014-10-01

Nanopores have emerged over the past two decades to become an important technique in single molecule experimental physics and biomolecule sensing. Recently DNA nanotechnology, in particular DNA origami, has been used for the formation of nanopores in insulating materials. DNA origami is a very attractive technique for the formation of nanopores since it enables the construction of 3D shapes with precise control over geometry and surface functionality. DNA origami has been applied to nanopore research by forming hybrid architectures with solid state nanopores and by direct insertion into lipid bilayers. This review discusses recent experimental work in this area and provides an outlook for future avenues and challenges. Copyright © 2014 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Shock response of nanoporous Cu--A molecular dynamics simulation

NASA Astrophysics Data System (ADS)

Zhao, Fengpeng

2015-06-01

Shock response of porous materials can be of crucial significance for shock physics and bears many practical applications in materials synthesis and engineering. Molecular dynamics simulations are carried out to investigate shock response of nanoporous metal materials, including elastic-plastic deformation, Hugoniot states, shock-induced melting, partial or complete void collapse, hotspot formation, nanojetting, and vaporization. A model nanoporous Cu with cylindrical voids and a high porosity under shocking is established to investigate such physical properties as velocity, temperature, density, stress and von Mises stress at different stages of compression and release. The elastic-plastic and overtaking shocks are observed at different shock strengths. A modified power-law P- α model is proposed to describe the Hugoniot states. The Grüneisen equation of state is validated. Shock-induced melting shows no clear signs of bulk premelting or superheating. Void collapse via plastic flow nucleated from voids, and the exact processes are shock strength dependent. With increasing shock strengths, void collapse transits from the ``geometrical'' mode (collapse of a void is dominated by crystallography and void geometry and can be different from that of one another) to ``hydrodynamic'' mode (collapse of a void is similar to one another). The collapse may be achieved predominantly by plastic flows along the {111} slip planes, by way of alternating compression and tension zones, by means of transverse flows, via forward and transverse flows, or through forward nano-jetting. The internal jetting induces pronounced shock front roughening, leading to internal hotspot formation and sizable high speed jets on atomically flat free surfaces. P. O. Box 919-401, Mianyang, 621900, Sichuan, PRC.

Chemical and Biological Resistant Clothing

DTIC Science & Technology

2013-04-01

for DMMP Measurement (Data from Samples with and without the Addition of Particulate Zeolite Sorbents... zeolite -NaA particles (which is a nanoporous zeolite with composition of [Na12(H2O)27][Al12Si12O48]) as dehydrating agent was added to the solution to...adsorb/remove water from the solution completely. The zeolite had a uniform pore diameter of ~0.41 nm, too small to accommodate DMMP molecules

Design of Stratified Functional Nanoporous Materials for CO 2 Capture and Conversion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, J. Karl; Ye, Jingyun

The objective of this project is to develop novel nanoporous materials for CO 2 capture and conversion. The motivation of this work is that capture of CO 2 from flue gas or the atmosphere coupled with catalytic hydrogenation of CO 2 into valuable chemicals and fuels can reduce the net amount of CO 2 in the atmosphere while providing liquid transportation fuels and other commodity chemicals. One approach to increasing the economic viability of carbon capture and conversion is to design a single material that can be used for both the capture and catalytic conversion of CO 2, because suchmore » a material could increase efficiency through process intensification. We have used density functional theory (DFT) methods to design catalytic moieties that can be incorporated into various metal organic framework (MOF) materials. We chose to work with MOFs because they are highly tailorable, can be functionalized, and have been shown to selectively adsorb CO 2 over N 2, which is a requirement for CO 2 capture from flue gas. Moreover, the incorporation of molecular catalytic moieties into MOF, through covalent bonding, produces a heterogeneous catalytic material having activities and selectivities close to those of homogeneous catalysts, but without the draw-backs associated with homogeneous catalysis.« less

Nanoporous Block Polymer Thin Films Functionalized with Bio-Inspired Ligands for the Efficient Capture of Heavy Metal Ions from Water.

PubMed

Weidman, Jacob L; Mulvenna, Ryan A; Boudouris, Bryan W; Phillip, William A

2017-06-07

Heavy metal contamination of water supplies poses a serious threat to public health, prompting the development of novel and sustainable treatment technologies. One promising approach is to molecularly engineer the chemical affinity of a material for the targeted removal of specific molecules from solution. In this work, nanoporous polymer thin films generated from tailor-made block polymers were functionalized with the bio-inspired moieties glutathione and cysteamine for the removal of heavy metal ions, including lead and cadmium, from aqueous solutions. In a single equilibrium stage, the films achieved removal rates of the ions in excess of 95%, which was consistent with predictions based on the engineered material properties. In a flow-through configuration, the thin films achieved an even greater removal rate of the metal ions. Furthermore, in mixed ion solutions the capacity of the thin films, and corresponding removal rates, did not demonstrate any reduction due to competitive adsorption effects. After such experiments the material was repeatedly regenerated quickly with no observed loss in capacity. Thus, these membranes provide a sustainable platform for the efficient purification of lead- and cadmium-contaminated water sources to safe levels. Moreover, their straightforward chemical modifications suggest that they could be engineered to treat sources containing other recalcitrant environmental contaminants as well.

A Scalable Route to Nanoporous Large-Area Atomically Thin Graphene Membranes by Roll-to-Roll Chemical Vapor Deposition and Polymer Support Casting.

PubMed

Kidambi, Piran R; Mariappan, Dhanushkodi D; Dee, Nicholas T; Vyatskikh, Andrey; Zhang, Sui; Karnik, Rohit; Hart, A John

2018-03-28

Scalable, cost-effective synthesis and integration of graphene is imperative to realize large-area applications such as nanoporous atomically thin membranes (NATMs). Here, we report a scalable route to the production of NATMs via high-speed, continuous synthesis of large-area graphene by roll-to-roll chemical vapor deposition (CVD), combined with casting of a hierarchically porous polymer support. To begin, we designed and built a two zone roll-to-roll graphene CVD reactor, which sequentially exposes the moving foil substrate to annealing and growth atmospheres, with a sharp, isothermal transition between the zones. The configurational flexibility of the reactor design allows for a detailed evaluation of key parameters affecting graphene quality and trade-offs to be considered for high-rate roll-to-roll graphene manufacturing. With this system, we achieve synthesis of uniform high-quality monolayer graphene ( I D / I G < 0.065) at speeds ≥5 cm/min. NATMs fabricated from the optimized graphene, via polymer casting and postprocessing, show size-selective molecular transport with performance comparable to that of membranes made from conventionally synthesized graphene. Therefore, this work establishes the feasibility of a scalable manufacturing process of NATMs, for applications including protein desalting and small-molecule separations.

Improving on aquaporins

DOE PAGES

Siwy, Zuzanna; Fornasiero, Francesco

2017-08-25

Biological nanopores can selectively and rapidly transport ions and molecules through membranes. For example, many biological ion channels conduct only one type of ion across the cell membrane, and they do so in response to external stimuli. Aquaporins transport water at astonishingly high rates and are efficient desalination units, in that they have excellent rejection of all ions, including protons. In conclusion, on page 792 of this issue, Tunuguntla et al. present an artificial nanopore system that sustains water fluxes exceeding those of aquaporins, exhibits ionic selectivities comparable to those of biological ion channels, and consists of carbon nanotubes (CNTs)more » that are 10 nm long and merely 0.8 nm in diameter embedded in a lipid bilayer.« less

Comparative Study of the Binding of Concanavalin A to Self-Assembled Monolayers Containing a Thiolated α-Mannoside on Flat Gold and on Nanoporous Gold

PubMed Central

Pandey, Binod; Tan, Yih Horng; Fujikawa, Kohki; Demchenko, Alexei V.

2013-01-01

We have prepared SAMs containing 8-mercaptooctyl α-D-mannopyranoside, either as a single component or in mixed SAMs with n-octanethiol on flat gold surfaces and on nanoporous gold. Electrochemical impedance spectroscopy showed that the mixed SAMs on flat gold surfaces showed the highest Con A binding near 1:9 solution molar ratio of thiolatedα-mannoside to n-octanethiol whereas those on NPG showed the highest response at 1:19 solution molar ratio of thiolated α-mannoside to n-octanethiol. Atomic force microscopy was employed to image the monolayers, and also to image the bound Con A protein. PMID:23519474

Development of Solid-State Nanopore Technology for Life Detection

NASA Technical Reports Server (NTRS)

Bywaters, K. B.; Schmidt, H.; Vercoutere, W.; Deamer, D.; Hawkins, A. R.; Quinn, R. C.; Burton, A. S.; Mckay, C. P.

2017-01-01

Biomarkers for life on Earth are an important starting point to guide the search for life elsewhere. However, the search for life beyond Earth should incorporate technologies capable of recognizing an array of potential biomarkers beyond what we see on Earth, in order to minimize the risk of false negatives from life detection missions. With this in mind, charged linear polymers may be a universal signature for life, due to their ability to store information while also inherently reducing the tendency of complex tertiary structure formation that significantly inhibit replication. Thus, these molecules are attractive targets for biosignature detection as potential "self-sustaining chemical signatures." Examples of charged linear polymers, or polyelectrolytes, include deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) as well as synthetic polyelectrolytes that could potentially support life, including threose nucleic acid (TNA) and other xenonucleic acids (XNAs). Nanopore analysis is a novel technology that has been developed for singlemolecule sequencing with exquisite single nucleotide resolution which is also well-suited for analysis of polyelectrolyte molecules. Nanopore analysis has the ability to detect repeating sequences of electrical charges in organic linear polymers, and it is not molecule- specific (i.e. it is not restricted to only DNA or RNA). In this sense, it is a better life detection technique than approaches that are based on specific molecules, such as the polymerase chain reaction (PCR), which requires that the molecule being detected be composed of DNA.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lian, Cheng; Univ. of California, Riverside, CA; Liu, Honglai

The ionophobicity effect of nanoporous electrodes on the capacitance and the energy storage capacity of nonaqueous-electrolyte supercapacitors is studied by means of the classical density functional theory (DFT). It has been hypothesized that ionophobic nanopores may create obstacles in charging, but they store energy much more efficiently than ionophilic pores. In this paper, we find that, for both ionic liquids and organic electrolytes, an ionophobic pore exhibits a charging behavior different from that of an ionophilic pore, and that the capacitance–voltage curve changes from a bell shape to a two-hump camel shape when the pore ionophobicity increases. For electric-double-layer capacitorsmore » containing organic electrolytes, an increase in the ionophobicity of the nanopores leads to a higher capacity for energy storage. Without taking into account the effects of background screening, the DFT predicts that an ionophobic pore containing an ionic liquid does not enhance the supercapacitor performance within the practical voltage ranges. However, by using an effective dielectric constant to account for ion polarizability, the DFT predicts that, like an organic electrolyte, an ionophobic pore with an ionic liquid is also able to increase the energy stored when the electrode voltage is beyond a certain value. We find that the critical voltage for an enhanced capacitance in an ionic liquid is larger than that in an organic electrolyte. Finally, our theoretical predictions provide further understanding of how chemical modification of porous electrodes affects the performance of supercapacitors.« less

Dynamics of Ice/Water Confined in Nanoporous Alumina.

PubMed

Suzuki, Yasuhito; Steinhart, Martin; Graf, Robert; Butt, Hans-Jürgen; Floudas, George

2015-11-19

Dielectric (DS), IR spectroscopy, and (1)H MAS NMR are employed in the study of ice/water confined in nanoporous alumina with pore diameters ranging from 400 nm down to 25 nm. Within nanoporous alumina there is a transformation from heterogeneous nucleation of hexagonal ice in the larger pores to homogeneous nucleation of cubic ice in the smaller pores. DS and IR show excellent agreement in the temperature interval and pore size dependence of the transformation. DS further revealed two dynamic processes under confinement. The "fast" and "slow" processes with an Arrhenius temperature dependence are attributed to ice and supercooled water relaxation, respectively. The main relaxation process of ice under confinement ("slow" process) has an activation energy of 44 ± 2 kJ/mol. The latter is in agreement with the reported relaxation times and activation energy of cubic ice prepared following a completely different route (by pressure). (1)H MAS NMR provided new insight in the state of ice structures as well as of supercooled water. Under confinement, a layer of liquid-like water coexists with ice structures. In addition, both ice structures under confinement appear to be more ordered than bulk hexagonal ice. Supercooled water in the smaller pores is different from bulk water. It shows a shift of the signal toward higher chemical shift values which may suggest stronger hydrogen bonding between the water molecules or increasing interactions with the AAO walls.

Computational Evaluation of Mg–Salen Compounds as Subsurface Fluid Tracers: Molecular Dynamics Simulations in Toluene–Water Mixtures and Clay Mineral Nanopores

DOE Office of Scientific and Technical Information (OSTI.GOV)

Greathouse, Jeffery A.; Boyle, Timothy J.; Kemp, Richard A.

Molecular tracers that can be selectively placed underground and uniquely identified at the surface using simple on-site spectroscopic methods would significantly enhance subsurface fluid monitoring capabilities. To ensure their widespread utility, the solubility of these tracers must be easily tuned to oil- or water-wet conditions as well as reducing or eliminating their propensity to adsorb onto subsurface rock and/or mineral phases. In this work, molecular dynamics simulations were used to investigate the relative solubilities and mineral surface adsorption properties of three candidate tracer compounds comprising Mg–salen derivatives of varying degrees of hydrophilic character. Simulations in water–toluene liquid mixtures indicate thatmore » the partitioning of each Mg–salen compound relative to the interface is strongly influenced by the degree of hydrophobicity of the compound. Simulations of these complexes in fluid-filled mineral nanopores containing neutral (kaolinite) and negatively charged (montmorillonite) mineral surfaces reveal that adsorption tendencies depend upon a variety of parameters, including tracer chemical properties, mineral surface type, and solvent type (water or toluene). Simulation snapshots and averaged density profiles reveal insight into the solvation and adsorption mechanisms that control the partitioning of these complexes in mixed liquid phases and nanopore environments. As a result, this work demonstrates the utility of molecular simulation in the design and screening of molecular tracers for use in subsurface applications.« less

Computational Evaluation of Mg–Salen Compounds as Subsurface Fluid Tracers: Molecular Dynamics Simulations in Toluene–Water Mixtures and Clay Mineral Nanopores

DOE PAGES

Greathouse, Jeffery A.; Boyle, Timothy J.; Kemp, Richard A.

2018-04-11

Molecular tracers that can be selectively placed underground and uniquely identified at the surface using simple on-site spectroscopic methods would significantly enhance subsurface fluid monitoring capabilities. To ensure their widespread utility, the solubility of these tracers must be easily tuned to oil- or water-wet conditions as well as reducing or eliminating their propensity to adsorb onto subsurface rock and/or mineral phases. In this work, molecular dynamics simulations were used to investigate the relative solubilities and mineral surface adsorption properties of three candidate tracer compounds comprising Mg–salen derivatives of varying degrees of hydrophilic character. Simulations in water–toluene liquid mixtures indicate thatmore » the partitioning of each Mg–salen compound relative to the interface is strongly influenced by the degree of hydrophobicity of the compound. Simulations of these complexes in fluid-filled mineral nanopores containing neutral (kaolinite) and negatively charged (montmorillonite) mineral surfaces reveal that adsorption tendencies depend upon a variety of parameters, including tracer chemical properties, mineral surface type, and solvent type (water or toluene). Simulation snapshots and averaged density profiles reveal insight into the solvation and adsorption mechanisms that control the partitioning of these complexes in mixed liquid phases and nanopore environments. As a result, this work demonstrates the utility of molecular simulation in the design and screening of molecular tracers for use in subsurface applications.« less

Highly effective hydrogen isotope separation in nanoporous metal-organic frameworks with open metal sites: direct measurement and theoretical analysis.

PubMed

Oh, Hyunchul; Savchenko, Ievgeniia; Mavrandonakis, Andreas; Heine, Thomas; Hirscher, Michael

2014-01-28

Separating gaseous mixtures that consist of very similar size is one of the critical issues in modern separation technology. Especially, the separation of the isotopes hydrogen and deuterium requires special efforts, even though these isotopes show a very large mass ratio. Conventionally, H/D separation can be realized through cryogenic distillation of the molecular species or the Girdler-sulfide process, which are among the most energy-intensive separation techniques in the chemical industry. However, costs can be significantly reduced by using highly mass-selective nanoporous sorbents. Here, we describe a hydrogen isotope separation strategy exploiting the strongly attractive open metal sites present in nanoporous metal-organic frameworks of the CPO-27 family (also referred to as MOF-74). A theoretical analysis predicts an outstanding hydrogen isotopologue separation at open metal sites due to isotopal effects, which has been directly observed through cryogenic thermal desorption spectroscopy. For H2/D2 separation of an equimolar mixture at 60 K, the selectivity of 12 is the highest value ever measured, and this methodology shows extremely high separation efficiencies even above 77 K. Our theoretical results imply also a high selectivity for HD/H2 separation at similar temperatures, and together with catalytically active sites, we propose a mechanism to produce D2 from HD/H2 mixtures with natural or enriched deuterium content.

Influence of HF acid catalyst concentration on properties of aerogel low-k thin films

NASA Astrophysics Data System (ADS)

Gaikwad, A. S.; Gupta, S. A.; Mahajan, A. M.

2016-08-01

The effect of hydrofluoric acid (HF) catalyst concentration in coating solution on chemical, physical and structural properties of silica aerogel thin films was investigated. The aerogel films were synthesized by using a sol-gel spin coating method followed by aging in ethanol and CO2 supercritical drying. The refractive index (RI) is observed to be reduced from 1.32 to 1.13 and porosity percentage increased from 30.21% to 71.64% in accordance with increasing HF concentration. Deposition of silica aerogel was confirmed from Fourier transform infrared spectroscopy measurement. The nanoporous nature of deposited films was confirmed from field effect scanning electron microscopy and observed pore diameter is in the range of 3.33 to 6.69 nm. The nanoporous nature of the film was also validated from atomic force microscopy and root mean square roughness was observed to be increased from 2.31 nm to 3.2 nm with increasing acid catalyst concentration in the coating solution. The calculated dielectric constant from CV measurement of fabricated metal-insulator-semiconductor structure for the silica aerogel formed at 0.8 ml HF concentration is observed to be 1.73. These deposited nanoporous silica aerogel low-k films with lower k value and smaller pore size have application as interlayer dielectric materials to minimize the disadvantages of porous materials.

Unique Three-Dimensional InP Nanopore Arrays for Improved Photoelectrochemical Hydrogen Production.

PubMed

Li, Qiang; Zheng, Maojun; Ma, Liguo; Zhong, Miao; Zhu, Changqing; Zhang, Bin; Wang, Faze; Song, Jingnan; Ma, Li; Shen, Wenzhong

2016-08-31

Ordered three-dimensional (3D) nanostructure arrays hold promise for high-performance energy harvesting and storage devices. Here, we report the fabrication of InP nanopore arrays (NPs) in unique 3D architectures with excellent light trapping characteristic and large surface areas for use as highly active photoelectrodes in photoelectrochemical (PEC) hydrogen evolution devices. The ordered 3D NPs were scalably synthesized by a facile two-step etching process of (1) anodic etching of InP in neutral 3 M NaCl electrolytes to realize nanoporous structures and (2) wet chemical etching in HCl/H3PO4 (volume ratio of 1:3) solutions for removing the remaining top irregular layer. Importantly, we demonstrated that the use of neutral electrolyte of NaCl instead of other solutions, such as HCl, in anodic etching of InP can significantly passivate the surface states of 3D NPs. As a result, the maximum photoconversion efficiency obtained with ∼15.7 μm thick 3D NPs was 0.95%, which was 7.3 and 1.4 times higher than that of planar and 2D NPs. Electrochemical impedance spectroscopy and photoluminescence analyses further clarified that the improved PEC performance was attributed to the enhanced charge transfer across 3D NPs/electrolyte interfaces, the improved charge separation at 3D NPs/electrolyte junction, and the increased PEC active surface areas with our unique 3D NP arrays.

SEM-induced shrinkage and site-selective modification of single-crystal silicon nanopores

NASA Astrophysics Data System (ADS)

Chen, Qi; Wang, Yifan; Deng, Tao; Liu, Zewen

2017-07-01

Solid-state nanopores with feature sizes around 5 nm play a critical role in bio-sensing fields, especially in single molecule detection and sequencing of DNA, RNA and proteins. In this paper we present a systematic study on shrinkage and site-selective modification of single-crystal silicon nanopores with a conventional scanning electron microscope (SEM). Square nanopores with measurable sizes as small as 8 nm × 8 nm and rectangle nanopores with feature sizes (the smaller one between length and width) down to 5 nm have been obtained, using the SEM-induced shrinkage technique. The analysis of energy dispersive x-ray spectroscopy and the recovery of the pore size and morphology reveal that the grown material along with the edge of the nanopore is the result of deposition of hydrocarbon compounds, without structural damage during the shrinking process. A simplified model for pore shrinkage has been developed based on observation of the cross-sectional morphology of the shrunk nanopore. The main factors impacting on the task of controllably shrinking the nanopores, such as the accelerating voltage, spot size, scanned area of e-beam, and the initial pore size have been discussed. It is found that single-crystal silicon nanopores shrink linearly with time under localized irradiation by SEM e-beam in all cases, and the pore shrinkage rate is inversely proportional to the initial equivalent diameter of the pore under the same e-beam conditions.

Nanochannel Device with Embedded Nanopore: a New Approach for Single-Molecule DNA Analysis and Manipulation

NASA Astrophysics Data System (ADS)

Zhang, Yuning; Reisner, Walter

2012-02-01

Nanopore and nanochannel based devices are robust methods for biomolecular sensing and single DNA manipulation. Nanopore-based DNA sensing has attractive features that make it a leading candidate as a single-molecule DNA sequencing technology. Nanochannel based extension of DNA, combined with enzymatic or denaturation-based barcoding schemes, is already a powerful approach for genome analysis. We believe that there is revolutionary potential in devices that combine nanochannels with nanpore detectors. In particular, due to the fast translocation of a DNA molecule through a standard nanopore configuration, there is an unfavorable trade-off between signal and sequence resolution. With a combined nanochannel-nanopore device, based on embedding a nanopore inside a nanochannel, we can in principle gain independent control over both DNA translocation speed and sensing signal, solving the key draw-back of the standard nanopore configuration. We will discuss our recent progress on device fabrication and characterization. In particular, we demonstrate that we can detect - using fluorescent microscopy - successful translocation of DNA from the nanochannel out through the nanopore, a possible method to 'select' a given barcode for further analysis. In particular, we show that in equilibrium DNA will not escape through an embedded sub-persistence length nanopore, suggesting that the embedded pore could be used as a nanoscale window through which to interrogate a nanochannel extended DNA molecule.

Quantifying short-lived events in multistate ionic current measurements.

PubMed

Balijepalli, Arvind; Ettedgui, Jessica; Cornio, Andrew T; Robertson, Joseph W F; Cheung, Kin P; Kasianowicz, John J; Vaz, Canute

2014-02-25

We developed a generalized technique to characterize polymer-nanopore interactions via single channel ionic current measurements. Physical interactions between analytes, such as DNA, proteins, or synthetic polymers, and a nanopore cause multiple discrete states in the current. We modeled the transitions of the current to individual states with an equivalent electrical circuit, which allowed us to describe the system response. This enabled the estimation of short-lived states that are presently not characterized by existing analysis techniques. Our approach considerably improves the range and resolution of single-molecule characterization with nanopores. For example, we characterized the residence times of synthetic polymers that are three times shorter than those estimated with existing algorithms. Because the molecule's residence time follows an exponential distribution, we recover nearly 20-fold more events per unit time that can be used for analysis. Furthermore, the measurement range was extended from 11 monomers to as few as 8. Finally, we applied this technique to recover a known sequence of single-stranded DNA from previously published ion channel recordings, identifying discrete current states with subpicoampere resolution.

Gas adsorption and capillary condensation in nanoporous alumina films.

PubMed

Casanova, Fèlix; Chiang, Casey E; Li, Chang-Peng; Roshchin, Igor V; Ruminski, Anne M; Sailor, Michael J; Schuller, Ivan K

2008-08-06

Gas adsorption and capillary condensation of organic vapors are studied by optical interferometry, using anodized nanoporous alumina films with controlled geometry (cylindrical pores with diameters in the range of 10-60 nm). The optical response of the film is optimized with respect to the geometric parameters of the pores, for potential performance as a gas sensor device. The average thickness of the adsorbed film at low relative pressures is not affected by the pore size. Capillary evaporation of the liquid from the nanopores occurs at the liquid-vapor equilibrium described by the classical Kelvin equation with a hemispherical meniscus. Due to the almost complete wetting, we can quantitatively describe the condensation for isopropanol using the Cohan model with a cylindrical meniscus in the Kelvin equation. This model describes the observed hysteresis and allows us to use the adsorption branch of the isotherm to calculate the pore size distribution of the sample in good agreement with independent structural measurements. The condensation for toluene lacks reproducibility due to incomplete surface wetting. This exemplifies the relevant role of the fluid-solid (van der Waals) interactions in the hysteretic behavior of capillary condensation.

Irradiation response and stability of nanoporous materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Engang; Wang, Yongqiang; Serrano De Caro, Magdalena

2012-08-28

Nanoporous materials consist of a regular organic or inorganic framework supporting a regular, porous structure. Pores are by definition roughly in the nanometre range, that is between 0.2 nm and 100 nm. Nanoporous materials can be subdivided into 3 categories (IUPAC): (1) Microporous materials - 0.2-2 nm; (2) Mesoporous materials - 2-50 nm; and (3) Macroporous materials - 50-1000 nm. np-Au foams were successfully synthesized by de-alloying process. np-Au foams remain porous structure after Ne ion irradiation to 1 dpa. Stacking Fault Tetrahedra (SFTs) were observed in RT irradiated np-Au foams under the highest and intermediate fluxes, but not undermore » the lowest flux. SFTs were not observed in LNT irradiated np-Au foams under all fluxes. The vacancy diffusivity in Au at RT is high enough so that the vacancies have enough time to agglomerate and then collapse to form SFTs. The high ion flux creates more damage per unit time; vacancies don't have enough time to diffuse or recombine. As a result, SFTs were formed at high ion fluxes.« less

Using Synthetic Nanopores for Single-Molecule Analyses: Detecting SNPs, Trapping DNA Molecules, and the Prospects for Sequencing DNA

ERIC Educational Resources Information Center

Dimitrov, Valentin V.

2009-01-01

This work focuses on studying properties of DNA molecules and DNA-protein interactions using synthetic nanopores, and it examines the prospects of sequencing DNA using synthetic nanopores. We have developed a method for discriminating between alleles that uses a synthetic nanopore to measure the binding of a restriction enzyme to DNA. There exists…

Modeling electrochemical deposition inside nanotubes to obtain metal-semiconductor multiscale nanocables or conical nanopores.

PubMed

Lebedev, Konstantin; Mafé, Salvador; Stroeve, Pieter

2005-08-04

Nanocables with a radial metal-semiconductor heterostructure have recently been prepared by electrochemical deposition inside metal nanotubes. First, a bare nanoporous polycarbonate track-etched membrane is coated uniformly with a metal film by electroless deposition. The film forms a working electrode for further deposition of a semiconductor layer that grows radially inside the nanopore when the deposition rate is slow. We propose a new physical model for the nanocable synthesis and study the effects of the deposited species concentration, potential-dependent reaction rate, and nanopore dimensions on the electrochemical deposition. The problem involves both axial diffusion through the nanopore and radial transport to the nanopore surface, with a surface reaction rate that depends on the axial position and the time. This is so because the radial potential drop across the deposited semiconductor layer changes with the layer thickness through the nanopore. Since axially uniform nanocables are needed for most applications, we consider the relative role of reaction and axial diffusion rates on the deposition process. However, in those cases where partial, empty-core deposition should be desirable (e.g., for producing conical nanopores to be used in single nanoparticle detection), we give conditions where asymmetric geometries can be experimentally realized.

Thermal conductivity model for nanoporous thin films

NASA Astrophysics Data System (ADS)

Huang, Congliang; Zhao, Xinpeng; Regner, Keith; Yang, Ronggui

2018-03-01

Nanoporous thin films have attracted great interest because of their extremely low thermal conductivity and potential applications in thin thermal insulators and thermoelectrics. Although there are some numerical and experimental studies about the thermal conductivity of nanoporous thin films, a simplified model is still needed to provide a straightforward prediction. In this paper, by including the phonon scattering lifetimes due to film thickness boundary scattering, nanopore scattering and the frequency-dependent intrinsic phonon-phonon scattering, a fitting-parameter-free model based on the kinetic theory of phonon transport is developed to predict both the in-plane and the cross-plane thermal conductivities of nanoporous thin films. With input parameters such as the lattice constants, thermal conductivity, and the group velocity of acoustic phonons of bulk silicon, our model shows a good agreement with available experimental and numerical results of nanoporous silicon thin films. It illustrates that the size effect of film thickness boundary scattering not only depends on the film thickness but also on the size of nanopores, and a larger nanopore leads to a stronger size effect of the film thickness. Our model also reveals that there are different optimal structures for getting the lowest in-plane and cross-plane thermal conductivities.

Single Protein Structural Analysis with a Solid-state Nanopore Sensor

NASA Astrophysics Data System (ADS)

Li, Jiali; Golovchenko, Jene; McNabb, David

2005-03-01

We report on the use of solid-state nanopore sensors to detect single polypeptides. These solid-state nanopores are fabricated in thin membranes of silicon nitride by ion beam sculpting...[1]. When an electrically biased nanopore is exposed to denatured proteins in ionic solution, discrete transient electronic signals: current blockages are observed. We demonstrate examples of such transient electronic signals for Bovine Serum Albumin (BSA) and human placental laminin M proteins in Guanidine hydrochloride solution, which suggest that these polypeptides are individually translocating through the nanopore during the detecting process. The amplitude of the current blockages is proportional to the bias voltage. No transient current blockages are observed when proteins are not present in the solution. To probe protein-folding state, pH and temperature dependence experiments are performed. The results demonstrate a solid-state nanopore sensor can be used to detect and analyze single polypeptide chains. Similarities and differences with signals obtained from double stranded DNA in a solid-state nanopore and single stranded DNA in a biological nanopore are discussed. [.1] Li, J., D. Stein, C. McMullan, D. Branton, M.J. Aziz, and J.A. Golovchenko, Ion-beam sculpting at nanometre length scales. Nature, 2001. 412(12 July): p. 166-169.

Hierarchical nanoporous metals as a path toward the ultimate three-dimensional functionality.

PubMed

Fujita, Takeshi

2017-01-01

Nanoporous metals prepared via dealloying or selective leaching of solid solution alloys and compounds represent an emerging class of materials. They possess a three-dimensional (3D) structure of randomly interpenetrating ligaments/nanopores with sizes between 5 nm and several tens of micrometers, which can be tuned by varying their preparation conditions (such as dealloying time and temperature) or additional thermal coarsening. As compared to other nanostructured materials, nanoporous metals have many advantages, including their bicontinuous structure, tunable pore sizes, bulk form, good electrical conductivity, and high structural stability. Therefore, nanoporous metals represent ideal 3D materials with versatile functionality, which can be utilized in various fields. In this review, we describe the recent applications of nanoporous metals in molecular detection, catalysis, 3D graphene synthesis, hierarchical pore formation, and additive manufacturing (3D printing) together with our own achievements in these areas. Finally, we discuss possible ways of realizing the ultimate 3D functionality beyond the scope of nanoporous metals.

Noise Properties of Rectifying Nanopore

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vlassiouk, Ivan V

2011-01-01

Ion currents through three types of rectifying nanoporous structures are studied and compared: conically shaped polymer nanopores, glass nanopipettes, and silicon nitride nanopores. Time signals of ion currents are analyzed by the power spectrum. We focus on the low-frequency range where the power spectrum magnitude scales with frequency, f, as 1/f. Glass nanopipettes and polymer nanopores exhibit nonequilibrium 1/f noise; thus, the normalized power spectrum depends on the voltage polarity and magnitude. In contrast, 1/f noise in rectifying silicon nitride nanopores is of equilibrium character. Various mechanisms underlying the voltage-dependent 1/f noise are explored and discussed, including intrinsic pore wallmore » dynamics and formation of vortices and nonlinear flow patterns in the pore. Experimental data are supported by modeling of ion currents based on the coupled Poisson-Nernst-Planck and Navier-Stokes equations. We conclude that the voltage-dependent 1/f noise observed in polymer and glass asymmetric nanopores might result from high and asymmetric electric fields, inducing secondary effects in the pore, such as enhanced water dissociation.« less

One-step synthesis of zero-dimensional hollow nanoporous gold nanoparticles with enhanced methanol electrooxidation performance.

PubMed

Pedireddy, Srikanth; Lee, Hiang Kwee; Tjiu, Weng Weei; Phang, In Yee; Tan, Hui Ru; Chua, Shu Quan; Troadec, Cedric; Ling, Xing Yi

2014-09-17

Nanoporous gold with networks of interconnected ligaments and highly porous structure holds stimulating technological implications in fuel cell catalysis. Current syntheses of nanoporous gold mainly revolve around de-alloying approaches that are generally limited by stringent and harsh multistep protocols. Here we develop a one-step solution phase synthesis of zero-dimensional hollow nanoporous gold nanoparticles with tunable particle size (150-1,000 nm) and ligament thickness (21-54 nm). With faster mass diffusivity, excellent specific electroactive surface area and large density of highly active surface sites, our zero-dimensional nanoporous gold nanoparticles exhibit ~1.4 times enhanced catalytic activity and improved tolerance towards carbonaceous species, demonstrating their superiority over conventional nanoporous gold sheets. Detailed mechanistic study also reveals the crucial heteroepitaxial growth of gold on the surface of silver chloride templates, implying that our synthetic protocol is generic and may be extended to the synthesis of other nanoporous metals via different templates.

Hierarchical nanoporous metals as a path toward the ultimate three-dimensional functionality

PubMed Central

Fujita, Takeshi

2017-01-01

Abstract Nanoporous metals prepared via dealloying or selective leaching of solid solution alloys and compounds represent an emerging class of materials. They possess a three-dimensional (3D) structure of randomly interpenetrating ligaments/nanopores with sizes between 5 nm and several tens of micrometers, which can be tuned by varying their preparation conditions (such as dealloying time and temperature) or additional thermal coarsening. As compared to other nanostructured materials, nanoporous metals have many advantages, including their bicontinuous structure, tunable pore sizes, bulk form, good electrical conductivity, and high structural stability. Therefore, nanoporous metals represent ideal 3D materials with versatile functionality, which can be utilized in various fields. In this review, we describe the recent applications of nanoporous metals in molecular detection, catalysis, 3D graphene synthesis, hierarchical pore formation, and additive manufacturing (3D printing) together with our own achievements in these areas. Finally, we discuss possible ways of realizing the ultimate 3D functionality beyond the scope of nanoporous metals. PMID:29057026

Theoretical and experimental studies on ionic currents in nanopore-based biosensors.

PubMed

Liu, Lei; Li, Chu; Ma, Jian; Wu, Yingdong; Ni, Zhonghua; Chen, Yunfei

2014-12-01

Novel generation of analytical technology based on nanopores has provided possibilities to fabricate nanofluidic devices for low-cost DNA sequencing or rapid biosensing. In this paper, a simplified model was suggested to describe DNA molecule's translocation through a nanopore, and the internal potential, ion concentration, ionic flowing speed and ionic current in nanopores with different sizes were theoretically calculated and discussed on the basis of Poisson-Boltzmann equation, Navier-Stokes equation and Nernst-Planck equation by considering several important parameters, such as the applied voltage, the thickness and the electric potential distributions in nanopores. In this way, the basic ionic currents, the modulated ionic currents and the current drops induced by translocation were obtained, and the size effects of the nanopores were carefully compared and discussed based on the calculated results and experimental data, which indicated that nanopores with a size of 10 nm or so are more advantageous to achieve high quality ionic current signals in DNA sensing.

Tailored nanoporous coatings fabricated on conformable polymer substrates.

PubMed

Poxson, David J; Mont, Frank W; Cho, Jaehee; Schubert, E Fred; Siegel, Richard W

2012-11-01

Nanoporous coatings have become the subject of intense investigation, in part because they have been shown to have unique and tailorable physical properties that can depart greatly from their dense or macroscopic counterparts. Nanoporous coatings are frequently fabricated utilizing oblique-angle or glancing-angle physical vapor-phase deposition techniques. However, a significant limitation for such coatings exists; they are almost always deposited on smooth and rigid planar substrates, such as silicon and glass. This limitation greatly constrains the applicability, tailorability, functionality and even the economic viability, of such nanoporous coatings. Here, we report our findings on nanoporous/polymer composite systems (NPCS) fabricated by utilizing oblique-angle electron-beam methodology. These unique composite systems exhibit several favorable characteristics, namely, (i) fine-tuned control over coating nanoporosity and thickness, (ii) excellent adhesion between the nanoporous coating and polymer substrate, (iii) the ability to withstand significant and repeated bending, and (iv) the ability to be molded conformably on two and three-dimensional surfaces while closely retaining the composite system's designed nanoporous film structure and, hence, properties.

DNA Origami-Graphene Hybrid Nanopore for DNA Detection.

PubMed

Barati Farimani, Amir; Dibaeinia, Payam; Aluru, Narayana R

2017-01-11

DNA origami nanostructures can be used to functionalize solid-state nanopores for single molecule studies. In this study, we characterized a nanopore in a DNA origami-graphene heterostructure for DNA detection. The DNA origami nanopore is functionalized with a specific nucleotide type at the edge of the pore. Using extensive molecular dynamics (MD) simulations, we computed and analyzed the ionic conductivity of nanopores in heterostructures carpeted with one or two layers of DNA origami on graphene. We demonstrate that a nanopore in DNA origami-graphene gives rise to distinguishable dwell times for the four DNA base types, whereas for a nanopore in bare graphene, the dwell time is almost the same for all types of bases. The specific interactions (hydrogen bonds) between DNA origami and the translocating DNA strand yield different residence times and ionic currents. We also conclude that the speed of DNA translocation decreases due to the friction between the dangling bases at the pore mouth and the sequencing DNA strands.

Impedance nanopore biosensor: influence of pore dimensions on biosensing performance.

PubMed

Kant, Krishna; Yu, Jingxian; Priest, Craig; Shapter, Joe G; Losic, Dusan

2014-03-07

Knowledge about electrochemical and electrical properties of nanopore structures and the influence of pore dimensions on these properties is important for the development of nanopore biosensing devices. The aim of this study was to explore the influence of nanopore dimensions (diameter and length) on biosensing performance using non-faradic electrochemical impedance spectroscopy (EIS). Nanoporous alumina membranes (NPAMs) prepared by self-ordered electrochemical anodization of aluminium were used as model nanopore sensing platforms. NPAMs with different pore diameters (25-65 nm) and lengths (4-18 μm) were prepared and the internal pore surface chemistry was modified by covalently attaching streptavidin and biotin. The performance of this antibody nanopore biosensing platform was evaluated using various concentrations of biotin as a model analyte. EIS measurements of pore resistivity and conductivity were carried out for pores with different diameters and lengths. The results showed that smaller pore dimensions of 25 nm and pore lengths up to 10 μm provide better biosensing performance.

The Influence of Nanopore Dimensions on the Electrochemical Properties of Nanopore Arrays Studied by Impedance Spectroscopy

PubMed Central

Kant, Krishna; Priest, Craig; Shapter, Joe G.; Losic, Dusan

2014-01-01

The understanding of the electrochemical properties of nanopores is the key factor for better understanding their performance and applications for nanopore-based sensing devices. In this study, the influence of pore dimensions of nanoporous alumina (NPA) membranes prepared by an anodization process and their electrochemical properties as a sensing platform using impedance spectroscopy was explored. NPA with four different pore diameters (25 nm, 45 nm and 65 nm) and lengths (5 μm to 20 μm) was used and their electrochemical properties were explored using different concentration of electrolyte solution (NaCl) ranging from 1 to 100 μM. Our results show that the impedance and resistance of nanopores are influenced by the concentration and ion species of electrolytes, while the capacitance is independent of them. It was found that nanopore diameters also have a significant influence on impedance due to changes in the thickness of the double layer inside the pores. PMID:25393785

One-step synthesis of zero-dimensional hollow nanoporous gold nanoparticles with enhanced methanol electrooxidation performance

NASA Astrophysics Data System (ADS)

Pedireddy, Srikanth; Lee, Hiang Kwee; Tjiu, Weng Weei; Phang, In Yee; Tan, Hui Ru; Chua, Shu Quan; Troadec, Cedric; Ling, Xing Yi

2014-09-01

Nanoporous gold with networks of interconnected ligaments and highly porous structure holds stimulating technological implications in fuel cell catalysis. Current syntheses of nanoporous gold mainly revolve around de-alloying approaches that are generally limited by stringent and harsh multistep protocols. Here we develop a one-step solution phase synthesis of zero-dimensional hollow nanoporous gold nanoparticles with tunable particle size (150-1,000 nm) and ligament thickness (21-54 nm). With faster mass diffusivity, excellent specific electroactive surface area and large density of highly active surface sites, our zero-dimensional nanoporous gold nanoparticles exhibit ~1.4 times enhanced catalytic activity and improved tolerance towards carbonaceous species, demonstrating their superiority over conventional nanoporous gold sheets. Detailed mechanistic study also reveals the crucial heteroepitaxial growth of gold on the surface of silver chloride templates, implying that our synthetic protocol is generic and may be extended to the synthesis of other nanoporous metals via different templates.

Nanoporous Ag prepared from the melt-spun Cu-Ag alloys

NASA Astrophysics Data System (ADS)

Li, Guijing; Song, Xiaoping; Sun, Zhanbo; Yang, Shengchun; Ding, Bingjun; Yang, Sen; Yang, Zhimao; Wang, Fei

2011-07-01

Nanoporous Ag ribbons with different morphology and porosity were achieved by the electrochemical corrosion of the melt-spun Cu-Ag alloys. The Cu-rich phase in the alloys was removed, resulting in the formation of the nanopores distributed across the whole ribbon. It is found that the structures, morphology and porosity of the nanoporous Ag ribbons were dependent on the microstructures of the parent alloys. The most of ligaments presented a rod-like shape due to the formation of pseudoeutectic microstructure in the melt-spun Cu 55Ag 45 and Cu 70Ag 30 alloys. For nanoporous Ag prepared from Cu 85Ag 15 alloys, the ligaments were camber-like because of the appearance of the divorced microstructures. Especially, a novel bamboo-grove-like structure could be observed at the cross-section of the nanoporous Ag ribbons. The experiment reveals that nanoporous Ag ribbons exhibited excellent enhancement of surface-enhanced Raman scattering (SERS) effect, but a slight difference existed due to the discrepancy of their morphology.

Electrochemical annealing of nanoporous gold by application of cyclic potential sweeps

PubMed Central

Sharma, Abeera; Bhattarai, Jay K.; Alla, Allan J.; Demchenko, Alexei V.; Stine, Keith J.

2015-01-01

An electrochemical method for annealing the pore sizes of nanoporous gold is reported. The pore sizes of nanoporous gold can be increased by electrochemical cycling with the upper potential limit being just at the onset of gold oxide formation. This study has been performed in electrolyte solutions including potassium chloride, sodium nitrate and sodium perchlorate. Scanning electron microscopy images have been used for ligament and pore size analysis. We examine the modifications of nanoporous gold due to annealing using electrochemical impedance spectroscopy, and cyclic voltammetry and offer a comparison of the surface coverage using the gold oxide stripping method as well as the method in which electrochemically accessible surface area is determined by using a diffusing redox probe. The effect of additives adsorbed on the nanoporous gold surface when subjected to annealing in different electrolytes as well as the subsequent structural changes in nanoporous gold are also reported. The effect of the annealing process on the application of nanoporous gold as a substrate for glucose electro-oxidation is briefly examined. PMID:25649027

Hierarchical nanoporous metals as a path toward the ultimate three-dimensional functionality

NASA Astrophysics Data System (ADS)

Fujita, Takeshi

2017-12-01

Nanoporous metals prepared via dealloying or selective leaching of solid solution alloys and compounds represent an emerging class of materials. They possess a three-dimensional (3D) structure of randomly interpenetrating ligaments/nanopores with sizes between 5 nm and several tens of micrometers, which can be tuned by varying their preparation conditions (such as dealloying time and temperature) or additional thermal coarsening. As compared to other nanostructured materials, nanoporous metals have many advantages, including their bicontinuous structure, tunable pore sizes, bulk form, good electrical conductivity, and high structural stability. Therefore, nanoporous metals represent ideal 3D materials with versatile functionality, which can be utilized in various fields. In this review, we describe the recent applications of nanoporous metals in molecular detection, catalysis, 3D graphene synthesis, hierarchical pore formation, and additive manufacturing (3D printing) together with our own achievements in these areas. Finally, we discuss possible ways of realizing the ultimate 3D functionality beyond the scope of nanoporous metals.

Lithography-based fabrication of nanopore arrays in freestanding SiN and graphene membranes

NASA Astrophysics Data System (ADS)

Verschueren, Daniel V.; Yang, Wayne; Dekker, Cees

2018-04-01

We report a simple and scalable technique for the fabrication of nanopore arrays on freestanding SiN and graphene membranes based on electron-beam lithography and reactive ion etching. By controlling the dose of the single-shot electron-beam exposure, circular nanopores of any size down to 16 nm in diameter can be fabricated in both materials at high accuracy and precision. We demonstrate the sensing capabilities of these nanopores by translocating dsDNA through pores fabricated using this method, and find signal-to-noise characteristics on par with transmission-electron-microscope-drilled nanopores. This versatile lithography-based approach allows for the high-throughput manufacturing of nanopores and can in principle be used on any substrate, in particular membranes made out of transferable two-dimensional materials.

Graphene nanopore devices for DNA sensing.

PubMed

Merchant, Chris A; Drndić, Marija

2012-01-01

We describe here a method for detecting the translocation of individual DNA molecules through nanopores created in graphene membranes. The devices consist of 1-5-nm thick graphene membranes with electron-beam sculpted nanopores from 5 to 10 nm in diameter. Due to the thin nature of the graphene membranes, and the reduced electrical resistance, we observe larger blocked currents than for traditional solid-state nanopores. We also show how ionic current noise levels can be reduced with the atomic-layer deposition of a few nanometers of titanium dioxide over the graphene surface. Unlike traditional solid-state nanopore materials that are insulating, graphene is an excellent electrical conductor, and its use opens the door to a new future class of nanopore devices in which electronic sensing and control is performed directly at the pore.

The Utility of Nanopore Technology for Protein and Peptide Sensing.

PubMed

Robertson, Joseph W F; Reiner, Joseph E

2018-06-28

Resistive-pulse nanopore sensing enables label-free single-molecule analysis of a wide range of analytes. An increasing number of studies have demonstrated the feasibility and usefulness of nanopore sensing for protein and peptide characterization. Nanopores offer the potential to study a variety of protein-related phenomena that includes unfolding kinetics, differences in unfolding pathways, protein structure stability and free energy profiles of DNA-protein and RNA-protein binding. In addition to providing a tool for fundamental protein characterization, nanopores have also been used as highly selective protein detectors in various solution mixtures and conditions. This review highlights these and other developments in the area of nanopore-based protein and peptide detection. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Ultrasonic modification of carbon materials for electrochemical capacitors

NASA Astrophysics Data System (ADS)

Rachiy, Bogdan I.; Nykoliuk, Marian O.; Budzulyak, Ivan M.; Kachmar, Andrii I.

2017-01-01

The paper is devoted to study the ultrasonic impact on the biomass of natural raw materials, which were used for the creation a nanoporous carbon material (NCM), which was used as electrode material for electrochemical capacitors (EC). The dry shells of apricot seeds were a feedstock, which were modified by the chemical treatment in the phosphoric acid and part of them were impacted by ultrasonic waves for 25 minutes. The NCM, which were obtained by carbonization at 550 °C, were modified by chemical treatment in the nitric acid. Thus, the different of modification NCM was obtained to compare their capacitance characteristics for EC. From experimental data we can do a conclusion, that ultrasonic modification and chemical treatment in nitric acidare improvecapacitance characteristics of NCM for EC.

Design and fabrication of asymmetric nanopores using pulsed PECVD

NASA Astrophysics Data System (ADS)

Kelkar, Sanket S.

Manipulating matter at nanometric length scales is important for many electronic, chemical and biological applications. Structures such as nanopores demonstrate a phenomenon known as hindered transport which can be exploited in analytical applications such as DNA sequencing, ionic transistors, and molecular sieving. Precisely controlling the size, geometry and surface characteristics of the nanopores is important for realizing these applications. In this work, we employ relatively large template structures (˜ 100 nm) produced by track-etching or electron beam lithography. The pore size is then reduced to the desired level by deposition of material using pulsed plasma enhanced chemical vapor deposition (PECVD). Pulsed PECVD has been developed as a high throughput alternative to atomic layer deposition (ALD) to deliver self-limiting growth of thin films. The goal of this thesis is to extend the application of pulsed PECVD to fabricate asymmetric nanopores. In contrast to ALD, pulsed PECVD does not result in perfectly conformal deposition profiles, and predicting the final nanostructure is more complicated. A two dimensional feature scale model was developed to predict film profile evolution. The model was built in COMSOL, and is based on a diffusion reaction framework with a spatially varying Knudsen diffusion coefficient to account for the molecular transport inside the features. A scaling analysis was used to account for ALD exposure limitations that commonly occur when coating these extremely high aspect ratio features. The model was verified by cross-section microscopy of deposition profiles on patterned cylinders and trenches. The model shows that it is possible to obtain unique nanopore morphologies in pulsed PECVD that are distinct from either steady state deposition processes such as physical vapor deposition (PVD) or conventional ALD. Polymeric track etched (TE) membrane supports with a nominal size of 100 nm were employed as model template structures to demonstrate the capability of pulsed PECVD for precise pore size reduction of model supports. The efficacy of pulsed PECVD for nanopore fabrication was compared to both ALD and PVD. Flux and solute rejection measurements demonstrate that the pulsed PECVD-modified TE membranes exhibit higher selectivity without compromising on the flux due to their asymmetric structure. For example, the TiO2 modified supports were demonstrated to deliver high retention (˜ 75%) of bovine serum albumin (BSA) protein while maintaining 70% of their initial pure water flux. PVD also forms asymmetric membranes that enable high flux. But due to morphological instabilities, reproducibility and control were poor in the PVD-modified membranes, and it was not possible to optimize the flux and the selectivity of the membranes simultaneously. Excellent agreement between measured flux and model predictions based on feature scale simulations provided further validation of the tool's fidelity. Since surface energetics can often dominate hindered transport, the kinetics and thermodynamics of the octadecyltrichlorosilane (OTS) attachment was investigated in-depth as an approach to convert hydrophilic metal oxides into hydrophobic surfaces. It was shown that a simple ozone treatment was a satisfactory alternative to hazardous acids to create the highly hydroxylated surface required for OTS attachment, and that using heptane as the solvent enabled the process to be conducted under ambient conditions without the need of a glovebox. The kinetics of OTS self-assembled monolayer (SAM) formation and the saturation contact angle (˜100°) on alumina are comparable to what has been observed for OTS attachment on silicon. The OTS SAMs also demonstrated excellent thermal stability, and the modified surface showed a critical surface tension of 21.4 dyne/cm.

What controls open-pore and residual currents in the first sensing zone of alpha-hemolysin nanopore? Combined experimental and theoretical study

NASA Astrophysics Data System (ADS)

de Biase, Pablo M.; Ervin, Eric N.; Pal, Prithwish; Samoylova, Olga; Markosyan, Suren; Keehan, Michael G.; Barrall, Geoffrey A.; Noskov, Sergei Yu.

2016-06-01

The electrophoretic transport of single-stranded DNA through biological nanopores such as alpha-hemolysin (αHL) is a promising and cost-effective technology with the potential to revolutionize genomics. The rational design of pores with the controlled polymer translocation rates and high contrast between different nucleotides could improve significantly nanopore sequencing applications. Here, we apply a combination of theoretical and experimental methods in an attempt to elucidate several selective modifications in the pore which were proposed to be central for the effective discrimination between purines and pyrimidines. Our nanopore test set includes the wild type αHL and six mutants (E111N/M113X/K147N) in which the cross-section and chemical functionality of the first constriction zone of the pore are modified. Electrophysiological recordings were combined with all-atom Molecular Dynamics simulations (MD) and a recently developed Brownian Dynamics (BROMOC) protocol to investigate residual ion currents and pore-DNA interactions for two homo-polymers e.g. poly(dA)40 or poly(dC)40 blocking the pore. The calculated residual currents and contrast in the poly(dA)40/poly(dC)40 blocked pore are in qualitative agreement with the experimental recordings. We showed that a simple structural metric allows rationalization of key elements in the emergent contrast between purines and pyrimidines in the modified αHL mutants. The shape of the pore and its capacity for hydrogen bonding to a translocated polynucleotide are two essential parameters for contrast optimization. To further probe the impact of these two factors in the ssDNA sensing, we eliminated the effect of the primary constriction using serine substitutions (i.e. E111S/M113S/T145S/K147S) and increased the hydrophobic volume of the central residue in the secondary constriction (L135I). This pore modification sharply increased the contrast between Adenine (A) and Cytosine (C).The electrophoretic transport of single-stranded DNA through biological nanopores such as alpha-hemolysin (αHL) is a promising and cost-effective technology with the potential to revolutionize genomics. The rational design of pores with the controlled polymer translocation rates and high contrast between different nucleotides could improve significantly nanopore sequencing applications. Here, we apply a combination of theoretical and experimental methods in an attempt to elucidate several selective modifications in the pore which were proposed to be central for the effective discrimination between purines and pyrimidines. Our nanopore test set includes the wild type αHL and six mutants (E111N/M113X/K147N) in which the cross-section and chemical functionality of the first constriction zone of the pore are modified. Electrophysiological recordings were combined with all-atom Molecular Dynamics simulations (MD) and a recently developed Brownian Dynamics (BROMOC) protocol to investigate residual ion currents and pore-DNA interactions for two homo-polymers e.g. poly(dA)40 or poly(dC)40 blocking the pore. The calculated residual currents and contrast in the poly(dA)40/poly(dC)40 blocked pore are in qualitative agreement with the experimental recordings. We showed that a simple structural metric allows rationalization of key elements in the emergent contrast between purines and pyrimidines in the modified αHL mutants. The shape of the pore and its capacity for hydrogen bonding to a translocated polynucleotide are two essential parameters for contrast optimization. To further probe the impact of these two factors in the ssDNA sensing, we eliminated the effect of the primary constriction using serine substitutions (i.e. E111S/M113S/T145S/K147S) and increased the hydrophobic volume of the central residue in the secondary constriction (L135I). This pore modification sharply increased the contrast between Adenine (A) and Cytosine (C). Electronic supplementary information (ESI) available: Statistical data on correlation between experimental and predicted conductance, ion densities in open and blocked pores and data on solvent structuring in nanopores. See DOI: 10.1039/c6nr00164e

Study of polymer molecules and conformations with a nanopore

DOEpatents

Golovchenko, Jene A.; Li, Jiali; Stein, Derek; Gershow, Marc H.

2013-03-12

The invention features methods for evaluating the conformation of a polymer, for example, for determining the conformational distribution of a plurality of polymers and to detect binding or denaturation events. The methods employ a nanopore which the polymer, e.g., a nucleic acid, traverses. As the polymer traverses the nanopore, measurements of transport properties of the nanopore yield data on the conformation of the polymer.

Study of polymer molecules and conformations with a nanopore

DOEpatents

Golovchenko, Jene A.; Li, Jiali; Stein, Derek; Gershow, Marc H.

2010-12-07

The invention features methods for evaluating the conformation of a polymer, for example, for determining the conformational distribution of a plurality of polymers and to detect binding or denaturation events. The methods employ a nanopore which the polymer, e.g., a nucleic acid, traverses. As the polymer traverses the nanopore, measurements of transport properties of the nanopore yield data on the conformation of the polymer.

Study of polymer molecules and conformations with a nanopore

DOEpatents

Golovchenko, Jene A; Li, Jiali; Stein, Derek; Gershow, Marc H

2015-03-03

The invention features methods for evaluating the conformation of a polymer, for example, for determining the conformational distribution of a plurality of polymers and to detect binding or denaturation events. The methods employ a nanopore which the polymer, e.g., a nucleic acid, traverses. As the polymer traverses the nanopore, measurements of transport properties of the nanopore yield data on the conformation of the polymer.

Integration of solid-state nanopores in a 0.5 μm cmos foundry process

PubMed Central

Uddin, A; Yemenicioglu, S; Chen, C-H; Corigliano, E; Milaninia, K; Theogarajan, L

2013-01-01

High-bandwidth and low-noise nanopore sensor and detection electronics are crucial in achieving single-DNA base resolution. A potential way to accomplish this goal is to integrate solid-state nanopores within a CMOS platform, in close proximity to the biasing electrodes and custom-designed amplifier electronics. Here we report the integration of solid-state nanopore devices in a commercial complementary metal-oxide semiconductor (CMOS) potentiostat chip implemented in On-Semiconductor’s 0.5 μm technology. Nanopore membranes incorporating electrodes are fabricated by post-CMOS micromachining utilizing the N+ polysilicon/SiO2/N+ polysilicon capacitor structure available in the aforementioned process. Nanopores are created in the CMOS process by drilling in a transmission electron microscope and shrinking by atomic layer deposition. We also describe a batch fabrication method to process a large of number of electrode-embedded nanopores with sub-10 nm diameter across CMOS-compatible wafers by electron beam lithography and atomic layer deposition. The CMOS-compatibility of our fabrication process is verified by testing the electrical functionality of on-chip circuitry. We observe high current leakage with the CMOS nanopore devices due to the ionic diffusion through the SiO2 membrane. To prevent this leakage, we coat the membrane with Al2O3 which acts as an efficient diffusion barrier against alkali ions. The resulting nanopore devices also exhibit higher robustness and lower 1/f noise as compared to SiO2 and SiNx. Furthermore, we propose a theoretical model for our low-capacitance CMOS nanopore devices, showing good agreement with the experimental value. In addition, experiments and theoretical models of translocation studies are presented using 48.5 kbp λ-DNA in order to prove the functionality of on-chip pores coated with Al2O3. PMID:23519330

Nanopore formation in neuroblastoma cells following ultrashort electric pulse exposure

NASA Astrophysics Data System (ADS)

Roth, Caleb C.; Payne, Jason A.; Wilmink, Gerald J.; Ibey, Bennett L.

2011-03-01

Ultrashort or nanosecond electrical pulses (USEP) cause repairable damage to the plasma membranes of cells through formation of nanopores. These nanopores are able to pass small ions such as sodium, calcium, and potassium, but remain impermeable to larger molecules like trypan blue and propidium iodide. What remains uncertain is whether generation of nanopores by ultrashort electrical pulses can inhibit action potentials in excitable cells. In this paper, we explored the sensitivity of excitable cells to USEP using Calcium Green AM 1 ester fluorescence to measure calcium uptake indicative of nanopore formation in the plasma membrane. We determined the threshold for nanopore formation in neuroblastoma cells for three pulse parameters (amplitude, pulse width, and pulse number). Measurement of such thresholds will guide future studies to determine if USEP can inhibit action potentials without causing irreversible membrane damage.

A novel input-parasitic compensation technique for a nanopore-based CMOS DNA detection sensor

NASA Astrophysics Data System (ADS)

Kim, Jungsuk

2016-12-01

This paper presents a novel input-parasitic compensation (IPC) technique for a nanopore-based complementary metal-oxide-semiconductor (CMOS) DNA detection sensor. A resistive-feedback transimpedance amplifier is typically adopted as the headstage of a DNA detection sensor to amplify the minute ionic currents generated from a nanopore and convert them to a readable voltage range for digitization. But, parasitic capacitances arising from the headstage input and the nanopore often cause headstage saturation during nanopore sensing, thereby resulting in significant DNA data loss. To compensate for the unwanted saturation, in this work, we propose an area-efficient and automated IPC technique, customized for a low-noise DNA detection sensor, fabricated using a 0.35- μm CMOS process; we demonstrated this prototype in a benchtop test using an α-hemolysin ( α-HL) protein nanopore.

Polyelectrolyte layer-by-layer deposition in cylindrical nanopores.

PubMed

Lazzara, Thomas D; Lau, K H Aaron; Abou-Kandil, Ahmed I; Caminade, Anne-Marie; Majoral, Jean-Pierre; Knoll, Wolfgang

2010-07-27

Layer-by-layer (LbL) deposition of polyelectrolytes within nanopores in terms of the pore size and the ionic strength was experimentally studied. Anodic aluminum oxide (AAO) membranes, which have aligned, cylindrical, nonintersecting pores, were used as a model nanoporous system. Furthermore, the AAO membranes were also employed as planar optical waveguides to enable in situ monitoring of the LbL process within the nanopores by optical waveguide spectroscopy (OWS). Structurally well-defined N,N-disubstituted hydrazine phosphorus-containing dendrimers of the fourth generation, with peripherally charged groups and diameters of approximately 7 nm, were used as the model polyelectrolytes. The pore diameter of the AAO was varied between 30-116 nm and the ionic strength was varied over 3 orders of magnitude. The dependence of the deposited layer thickness on ionic strength within the nanopores is found to be significantly stronger than LbL deposition on a planar surface. Furthermore, deposition within the nanopores can become inhibited even if the pore diameter is much larger than the diameter of the G4-polyelectrolyte, or if the screening length is insignificant relative to the dendrimer diameter at high ionic strengths. Our results will aid in the template preparation of polyelectrolyte multilayer nanotubes, and our experimental approach may be useful for investigating theories regarding the partitioning of nano-objects within nanopores where electrostatic interactions are dominant. Furthermore, we show that the enhanced ionic strength dependence of polyelectrolyte transport within the nanopores can be used to selectively deposit a LbL multilayer atop a nanoporous substrate.

Adiabatic burst evaporation from bicontinuous nanoporous membranes

PubMed Central

Ichilmann, Sachar; Rücker, Kerstin; Haase, Markus; Enke, Dirk

2015-01-01

Evaporation of volatile liquids from nanoporous media with bicontinuous morphology and pore diameters of a few 10 nm is an ubiquitous process. For example, such drying processes occur during syntheses of nanoporous materials by sol–gel chemistry or by spinodal decomposition in the presence of solvents as well as during solution impregnation of nanoporous hosts with functional guests. It is commonly assumed that drying is endothermic and driven by non-equilibrium partial pressures of the evaporating species in the gas phase. We show that nearly half of the liquid evaporates in an adiabatic mode involving burst-like liquid-to-gas conversions. During single adiabatic burst evaporation events liquid volumes of up to 107 μm3 are converted to gas. The adiabatic liquid-to-gas conversions occur if air invasion fronts get unstable because of the built-up of high capillary pressures. Adiabatic evaporation bursts propagate avalanche-like through the nanopore systems until the air invasion fronts have reached new stable configurations. Adiabatic cavitation bursts thus compete with Haines jumps involving air invasion front relaxation by local liquid flow without enhanced mass transport out of the nanoporous medium and prevail if the mean pore diameter is in the range of a few 10 nm. The results reported here may help optimize membrane preparation via solvent-based approaches, solution-loading of nanopore systems with guest materials as well as routine use of nanoporous membranes with bicontinuous morphology and may contribute to better understanding of adsorption/desorption processes in nanoporous media. PMID:25926406

Propylene/propane permeation properties of ethyl cellulose (EC) mixed matrix membranes fabricated by incorporation of nanoporous graphene nanosheets

PubMed Central

Yuan, Bingbing; Sun, Haixiang; Wang, Tao; Xu, Yanyan; Li, Peng; Kong, Ying; Niu, Q. Jason

2016-01-01

Nanopore containing graphene nanosheets were synthesized by graphene oxide and a reducing agent using a facile hydrothermal treatment in sodium hydroxide media. The as-prepared nanoporous graphene was incorporated into ethyl cellulose (EC) to prepare the mixed matrix membranes (MMMs) for C3H6/C3H8 separation. Transmission electron microscopy (TEM) photograph and X-ray photoelectron spectroscopy (XPS) analysis of nanoporous graphene nanosheets indicated that the structure of nano-pore was irregular and the oxygen-containing groups in the surface were limited. More importantly, the as-prepared MMMs presented better separation performance than that of pristine EC membrane due to simultaneous enhancement of C3H6 permeability and ideal selectivity. The ideal selectivity of the MMMs with 1.125 wt‰ nanoporous graphene content for C3H6/C3H8 increased from 3.45 to 10.42 and the permeability of C3H6 increased from 57.9 Barrer to 89.95 Barrer as compared with the pristine membrane. The presumed facilitated mechanism was that the high specific surface area of nanoporous graphene in polymer matrix increased the length of the tortuous pathway formed by nanopores for the gas diffusion as compared with the pristine graphene nanosheets, and generated a rigidified interface between the EC chains and fillers, thus enhanced the diffusivity selectivity. Therefore, it is expected that nanoporous graphene would be effective material for the C3H6/C3H8 separation. PMID:27352851

Creation of nanopores on graphene planes with MgO template for preparing high-performance supercapacitor electrodes

NASA Astrophysics Data System (ADS)

Wang, Huanjing; Sun, Xiuxia; Liu, Zonghuai; Lei, Zhibin

2014-05-01

Creation of nanopores on graphene planar sheets is of great significance in promoting the kinetic diffusion of electrolyte and enhancing the utilization efficiency of graphene planar sheets. Herein, we developed a facile chemical vapor deposition strategy to prepare highly porous graphene with flake-like MgO as template and ferrocene as the carbon precursor. The graphene layers show a highly porous structure with small mesopores of 4-8 nm, large mesopores of 10-20 nm and additional macropores of 100-200 nm. These nanopores on graphene sheets provide numerous channels for fast ion transport perpendicular to the 2D basal plane, while the good powder conductivity ensures an effective electron propagation within the 2D graphene plane. As a result, a specific capacitance of 303 F g-1, an areal capacitance up to 17.3 μF cm-2 and a nearly tenfold shorter time constant were achieved when compared with those of nonporous and stacked graphene electrodes. The method demonstrated herein would open up an opportunity to prepare porous graphene for a wide applications in energy storage, biosensors, nanoelectronics and catalysis.Creation of nanopores on graphene planar sheets is of great significance in promoting the kinetic diffusion of electrolyte and enhancing the utilization efficiency of graphene planar sheets. Herein, we developed a facile chemical vapor deposition strategy to prepare highly porous graphene with flake-like MgO as template and ferrocene as the carbon precursor. The graphene layers show a highly porous structure with small mesopores of 4-8 nm, large mesopores of 10-20 nm and additional macropores of 100-200 nm. These nanopores on graphene sheets provide numerous channels for fast ion transport perpendicular to the 2D basal plane, while the good powder conductivity ensures an effective electron propagation within the 2D graphene plane. As a result, a specific capacitance of 303 F g-1, an areal capacitance up to 17.3 μF cm-2 and a nearly tenfold shorter time constant were achieved when compared with those of nonporous and stacked graphene electrodes. The method demonstrated herein would open up an opportunity to prepare porous graphene for a wide applications in energy storage, biosensors, nanoelectronics and catalysis. Electronic supplementary information (ESI) available: TGA curve, SEM and XRD patterns of MgO; TEM image of Mg5(CO3)4(OH)2.4H2O HRTEM; Raman spectrum of porous graphene, and its electrochemical performance including CV and galvanostatic charge-discharge curves in a three-electrode cell with 6.0 mol L-1 aqueous KOH as electrolyte; comparative electrocapacitive performances of graphene materials prepared by various methods; CV behaviors of porous graphene in two-electrode cell and the last 10 cycles in 1000 charge-discharge cycles in 1.0 mol L-1 TEABF4/AN electrolyte. See DOI: 10.1039/c4nr00538d

A smart temperature and magnetic-responsive gating carbon nanotube membrane for ion and protein transportation

PubMed Central

Cong, Hailin; Xu, Xiaodan; Yu, Bing; Yang, Zhaohui; Zhang, Xiaoyan

2016-01-01

Carbon nanotube (CNT) nanoporous membranes based on pre-aligned CNTs have superior nano-transportation properties in biological science. Herein, we report a smart temperature- and temperature-magnetic-responsive CNT nanoporous membrane (CNM) by grafting thermal-sensitive poly(N-isopropylacrylamide) (PNIPAM) and Fe3O4 nanoparticles (Fe3O4-NPs) on the open ends of pre-aligned CNTs with a diameter around 15 nm via surface-initiated atom transfer radical polymerization (SI-ATRP) method. The inner cavity of the modified CNTs in the membrane is designed to be the only path for ion and protein transportation, and its effective diameter with a variation from ~5.7 nm to ~12.4 nm can be reversible tuned by temperature and magnetic field. The PNIPAM modified CNM (PNIPAM-CNM) and PNIPAM magnetic nanoparticles modified CNM (PNIPAM-MAG-CNM) exhibit excellent temperature- or temperature-magnetic-responsive gating property to separate proteins of different sizes. The PNIPAM-CNMs and PNIPAM-MAG-CNMs have potential applications in making artificial cells, biosensors, bioseparation and purification filters. PMID:27535103

Fast-Response, Sensitivitive and Low-Powered Chemosensors by Fusing Nanostructured Porous Thin Film and IDEs-Microheater Chip

PubMed Central

Dai, Zhengfei; Xu, Lei; Duan, Guotao; Li, Tie; Zhang, Hongwen; Li, Yue; Wang, Yi; Wang, Yuelin; Cai, Weiping

2013-01-01

The chemiresistive thin film gas sensors with fast response, high sensitivity, low power consumption and mass-produced potency, have been expected for practical application. It requires both sensitive materials, especially exquisite nanomaterials, and efficient substrate chip for heating and electrical addressing. However, it is challenging to achieve repeatable microstructures across the films and low power consumption of substrate chip. Here we presented a new sensor structure via the fusion of metal-oxide nanoporous films and micro-electro-mechanical systems (MEMS)-based sensing chip. An interdigital-electrodes (IDEs) and microheater integrated MEMS structure is designed and employed as substrate chip to in-situ fabricate colloidal monolayer template-induced metal-oxide (egg. SnO2) nanoporous sensing films. This fused sensor demonstrates mW-level low power, ultrafast response (~1 s), and parts-per-billion lever detection for ethanol gas. Due to the controllable template strategy and mass-production potential, such micro/nano fused high-performance gas sensors will be next-generation key miniaturized/integrated devices for advanced practical applications. PMID:23591580

Cascaded nano-porous silicon for high sensitive biosensing and functional group distinguishing by Mid-IR spectra.

PubMed

Nguyen, Minh-Hang; Tsai, Hau-Jie; Wu, Jen-Kuei; Wu, Yi-Shiuan; Lee, Ming-Chang; Tseng, Fan-Gang

2013-09-15

We present a chemical-biosensor in the Mid-IR range and based on cascaded porous silicon made on p- and n-type (100) silicon substrates of resistivities between 0.001Ωcm and 0.005Ωcm. The stacked porous layers of various porosities (20-80%) and thicknesses (5-9μm) are formed by successive electrochemical etchings with different current densities. Working with FTIR technique that possesses fast response, high sensitivity, and capability of detecting and identifying functional groups, the cascaded porous structures provided enhanced refractive index sensitivities and reduced detection limits in chemical and biodetection. The largest wavenumber shifts were 50cm(-1)/mM obtained for d-(+)-glucose and 96cm(-1)/μg/mL for Cy5-conjungated Rabbit Anti-Mouse IgG. The lowest detectable concentration of glucose was 80μM (1.4mg/mL) with PS porosity of 40% and thickness of about 9μm while it was 40ng/mL for Cy5-conjugated Rabbit Anti-Mouse IgG which is 2.5×10(5) folds better than those in literature. Copyright © 2013 Elsevier B.V. All rights reserved.

Portable SERS sensor for malachite green and other small dye molecules

NASA Astrophysics Data System (ADS)

Qiu, Suyan; Zhao, Fusheng; Li, Jingting; Shih, Wei-Chuan

2017-02-01

Sensitive detection of specific chemicals on site can be extremely powerful in many fields. Owing to its molecular fingerprinting capability, surface-enhanced Raman scattering has been one of the technological contenders. In this paper, we describe the novel use of DNA topological nanostructure on nanoporous gold nanoparticle (NPG-NP) array chip for chemical sensing. NPG-NP features large surface area and high-density plasmonic field enhancement known as "hotspots". Hence, NPG-NP array chip has found many applications in nanoplasmonic sensor development. This technique can provide novel label-free molecular sensing capability and enables high sensitivity and specificity detection using a portable Raman spectrometer.

Amphotericin B channels in phospholipid membrane-coated nanoporous silicon surfaces: implications for photovoltaic driving of ions across membranes.

PubMed

Yilma, Solomon; Liu, Nangou; Samoylov, Alexander; Lo, Ting; Brinker, C Jeffrey; Vodyanoy, Vitaly

2007-03-15

The antimycotic agent amphotericin B (AmB) functions by forming complexes with sterols to form ion channels that cause membrane leakage. When AmB and cholesterol mixed at 2:1 ratio were incorporated into phospholipid bilayer membranes formed on the tip of patch pipettes, ion channel current fluctuations with characteristic open and closed states were observed. These channels were also functional in phospholipid membranes formed on nanoporous silicon surfaces. Electrophysiological studies of AmB-cholesterol mixtures that were incorporated into phospholipid membranes formed on the surface of nanoporous (6.5 nm pore diameter) silicon plates revealed large conductance ion channels ( approximately 300 pS) with distinct open and closed states. Currents through the AmB-cholesterol channels on nanoporous silicon surfaces can be driven by voltage applied via conventional electrical circuits or by photovoltaic electrical potential entirely generated when the nanoporous silicon surface is illuminated with a narrow laser beam. Electrical recordings made during laser illumination of AmB-cholesterol containing membrane-coated nanoporous silicon surfaces revealed very large conductance ion channels with distinct open and closed states. Our findings indicate that nanoporous silicon surfaces can serve as mediums for ion-channel-based biosensors. The photovoltaic properties of nanoporous silicon surfaces show great promise for making such biosensors addressable via optical technologies.

Ultrafine nanoporous palladium-aluminum film fabricated by citric acid-assisted hot-water-treatment of aluminum-palladium alloy film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harumoto, Takashi; Tamura, Yohei; Ishiguro, Takashi, E-mail: ishiguro@rs.noda.tus.ac.jp

Hot-water-treatment has been adapted to fabricate ultrafine nanoporous palladium-aluminum film from aluminum-palladium alloy film. Using citric acid as a chelating agent, a precipitation of boehmite (aluminum oxide hydroxide, AlOOH) on the nanoporous palladium-aluminum film was suppressed. According to cross-sectional scanning transmission electron microscopy observations, the ligament/pore sizes of the prepared nanoporous film were considerably small (on the order of 10 nm). Since this fabrication method only requires aluminum alloy film and hot-water with chelating agent, the ultrafine nanoporous film can be prepared simply and environmentally friendly.

Simultaneous Size Control of Microcapsule and Its Nanopores Using Polymer Concentration

NASA Astrophysics Data System (ADS)

Cha, Jemyung; Jeong, Eun Ho; Takahiro, Arakawa; Kim, Kyung Chun; Shoji, Shuich; Go, Jeung Sang

2010-03-01

Polymeric microcapsules with nanopores are produced using the droplet-based self-assembly of a block copolymer in the microfluidic channel. Differently from the conventional wise, the sizes of the microcapsule and its nanopores are controlled by changing the concentration of the block copolymer dissolved in an organic solvent. The increase in the polymer concentration shows the increase in the size of the microcapsule and the decrease of the size and number of the nanopores. Also, to obtain the optimal morphology of the nanopores in the microcapsule, the removal process of a surfactant is newly developed by using a microporous metal mesh.

Thermoelectric studies of nanoporous thin films with adjusted pore-edge charges

NASA Astrophysics Data System (ADS)

Hao, Qing; Zhao, Hongbo; Xu, Dongchao

2017-03-01

In recent years, nanoporous thin films have been widely studied for thermoelectric applications. High thermoelectric performance is reported for nanoporous Si films, which is attributed to the dramatically reduced lattice thermal conductivity and bulk-like electrical properties. Porous materials can also be used in gas sensing applications by engineering the surface-trapped charges on pore edges. In this work, an analytical model is developed to explore the relationship between the thermoelectric properties and pore-edge charges in a periodic two-dimensional nanoporous material. The presented model can be widely used to analyze the measured electrical properties of general nanoporous thin films and two-dimensional materials.

EDITORIAL: Nanotechnological selection Nanotechnological selection

NASA Astrophysics Data System (ADS)

Demming, Anna

2013-01-01

At the nanoscale measures can move from a mass-scale analogue calibration to counters of discrete units. The shift redefines the possible levels of control that can be achieved in a system if adequate selectivity can be imposed. As an example as ionic substances pass through nanoscale pores, the quantity of ions is low enough that the pore can contain either negative or positive ions. Yet precise control over this selectivity still raises difficulties. In this issue researchers address the challenge of how to regulate the ionic selectivity of negative and positive charges with the use of an external charge. The approach may be useful for controlling the behaviour, properties and chemical composition of liquids and has possible technical applications for nanofluidic field effect transistors [1]. Selectivity is a critical advantage in the administration of drugs. Nanoparticles functionalized with targeting moieties can allow delivery of anti-cancer drugs to tumour cells, whilst avoiding healthy cells and hence reducing some of the debilitating side effects of cancer treatments [2]. Researchers in Belarus and the US developed a new theranostic approach—combining therapy and diagnosis—to support the evident benefits of cellular selectivity that can be achieved when nanoparticles are applied in medicine [3]. Their process uses nanobubbles of photothermal vapour, referred to as plasmonic nanobubbles, generated by plasmonic excitations in gold nanoparticles conjugated to diagnosis-specific antibodies. The intracellular plasmonic nanobubbles are controlled by laser fluence so that the response can be tuned in individual living cells. Lower fluence allows non-invasive high-sensitive imaging for diagnosis and higher fluence can disrupt the cellular membrane for treatments. The selective response of carbon nanotubes to different gases has leant them to be used within various different types of sensors, as summarized in a review by researchers at the University of California, Riverside [4]. Mangu et al in the US have developed highly sensitive and selective room temperature gas sensors made from composites of multiwalled carbon nanotubes and polymers [5]. They report sensitivities as high as 28% when exposed to 100 ppm of NH3 and 29.8% to 100 ppm of NO2. Nanopore structures are also showing increasing promise for sensing and biophysical characterization applications, in particular DNA [6]. An applied potential drives negatively charged DNA molecules through nanopores in a membrane and gives rise to current blockage pulses that are characteristic of specific analytes. Solid-state nanopore structures hold advantages over biological pores, such as those in α-haemolysin protein, as they are more resilient to experimental conditions, and ideally should also allow control of the nanopore diameter, channel length and surface composition. Asghar and colleagues have now reported a method that enables just that, 'a rapid solid-state nanopore fabrication and controlled pore shrinking process which does provide simultaneous in situ control of surface properties' [7]. In addition, they demonstrate the viability of the approach for single molecule sensor applications using double-stranded DNA. In this issue, researchers in China report on a different approach which allows control over the transport of ionic fluids through nanopore-type structures. They describe the rapid field effect control of electrical conductance in single nanotube nanofluidic transistors [1]. Rather than seeking to control the charge of thenanotube inner surface, Gong and colleagues control polarity switching based on negative and positive ion selectivity using an external charge. 'The polarity of the nanotube can be reversed and tuned by the external field, which could find interesting applications in the field of ion separation and energy conversion', they explain, adding that the system may also find a use as a voltage sensor through the detection of the type of ions across the channel. The aim of achieving selectivity encompasses a huge range of fields in nanotechnology research, from sensing and medicine to nanoelectronics and self-assembly. As our understanding of how nanosystems behave deepens, so too does the hunger to improve our capabilities, allowing greater precision and control in manipulating these systems. Selectivity is far from trivial when shrinking to systems of nanoscale dimensions, but the range of opportunities it brings just keeps on growing. References [1] Gong X, Li J, Guo C, Xu K and Hui Y 2012 Molecular switch for tuning ions across nanopores by an external electric field Nanotechnology 24 025502 [2] Brannon-Peppas L and Blanchette J O 2004 Nanoparticle and targeted systems for cancer therapy Adv. Drug Deliv. Rev 56 1649-59 [3] Lukianova-Hleb E Y, Hanna E Y, Hafner J H and Lapotko D O 2010 Tunable plasmonic nanobubbles for cell theranostics Nanotechnology 21 085102 [4] Zhang T, Mubeen S, Myung N V and Deshusses M A 2008 Recent progress in carbon nanotube-based gas sensors Nanotechnology 19 332001 [5] Mangu R, Rajaputra S and Singh V P 2011 MWCNT-polymer composites as highly sensitive and selective room temperature gas sensors Nanotechnology 22 215502 [6]Meller A, Nivon L, Brandin E, Golovchenko J and Branton D 2000 Rapid nanopore discrimination between single polynucleotide molecules Proc. Natl Acad. Sci. 97 1079-84 [7] Asghar W, Ilyas A, Deshmukh R R, Sumitsawan S, Timmons R B and Iqbal S M 2011 Pulsed plasma polymerization for controlling shrinkage and surface composition of nanopores Nanotechnology 22 285304

Extremely durable biofouling-resistant metallic surfaces based on electrodeposited nanoporous tungstite films on steel

PubMed Central

Tesler, Alexander B.; Kim, Philseok; Kolle, Stefan; Howell, Caitlin; Ahanotu, Onye; Aizenberg, Joanna

2015-01-01

Formation of unwanted deposits on steels during their interaction with liquids is an inherent problem that often leads to corrosion, biofouling and results in reduction in durability and function. Here we report a new route to form anti-fouling steel surfaces by electrodeposition of nanoporous tungsten oxide (TO) films. TO-modified steels are as mechanically durable as bare steel and highly tolerant to compressive and tensile stresses due to chemical bonding to the substrate and island-like morphology. When inherently superhydrophilic TO coatings are converted to superhydrophobic, they remain non-wetting even after impingement with yttria-stabilized-zirconia particles, or exposure to ultraviolet light and extreme temperatures. Upon lubrication, these surfaces display omniphobicity against highly contaminating media retaining hitherto unseen mechanical durability. To illustrate the applicability of such a durable coating in biofouling conditions, we modified naval construction steels and surgical instruments and demonstrated significantly reduced marine algal film adhesion, Escherichia coli attachment and blood staining. PMID:26482559

Nano Petri dishes: a new polystyrene platform for studying cell-nanoengineered surface interactions

NASA Astrophysics Data System (ADS)

Cha, Kyoung Je; Na, Moon-Hee; Kim, Hyung Woo; Kim, Dong Sung

2014-05-01

In this study, we fabricated and fully characterized a new type of polystyrene (PS) cell-culture platform containing nanoengineered surfaces (NES), referred to as a nano Petri dish, which can be used at the transition stage of basic cell-NES interaction studies for clinical applications. Nano-injection molding in this study was used for the mass production of the nano Petri dish having nanopore arrays. The effects of processing parameters of the injection molding on the replication quality of the nanopore arrays were quantitatively evaluated by means of design of experiments based on the Taguchi method. This allowed efficient and reliable cell culture studies by providing large numbers of the same dishes, in addition to removing the fixation step of the NES plates inside the cell-culture container. Physical, chemical and mechanical properties of the NES, as well as cell behavior including attachment and proliferation of human osteosarcoma MG-63 cells on the NES, were then characterized, with and without the oxygen plasma surface treatment.

Extremely durable biofouling-resistant metallic surfaces based on electrodeposited nanoporous tungstite films on steel

NASA Astrophysics Data System (ADS)

Tesler, Alexander B.; Kim, Philseok; Kolle, Stefan; Howell, Caitlin; Ahanotu, Onye; Aizenberg, Joanna

2015-10-01

Formation of unwanted deposits on steels during their interaction with liquids is an inherent problem that often leads to corrosion, biofouling and results in reduction in durability and function. Here we report a new route to form anti-fouling steel surfaces by electrodeposition of nanoporous tungsten oxide (TO) films. TO-modified steels are as mechanically durable as bare steel and highly tolerant to compressive and tensile stresses due to chemical bonding to the substrate and island-like morphology. When inherently superhydrophilic TO coatings are converted to superhydrophobic, they remain non-wetting even after impingement with yttria-stabilized-zirconia particles, or exposure to ultraviolet light and extreme temperatures. Upon lubrication, these surfaces display omniphobicity against highly contaminating media retaining hitherto unseen mechanical durability. To illustrate the applicability of such a durable coating in biofouling conditions, we modified naval construction steels and surgical instruments and demonstrated significantly reduced marine algal film adhesion, Escherichia coli attachment and blood staining.

Nanoporous metal organic frameworks as hybrid polymer-metal composites for drug delivery and biomedical applications.

PubMed

Beg, Sarwar; Rahman, Mahfoozur; Jain, Atul; Saini, Sumant; Midoux, Patrick; Pichon, Chantal; Ahmad, Farhan Jalees; Akhter, Sohail

2017-04-01

Metal organic frameworks (MOFs), porous hybrid polymer-metal composites at the nanoscale, are recent innovations in the field of chemistry; they are novel polymeric materials with diverse biomedical applications. MOFs are nanoporous materials, consisting of metal ions linked together by organic bridging ligands. The unique physical and chemical characteristics of MOFs have attracted wider attention from the scientific community, exploring their utility in the field of material science, biology, nanotechnology and drug delivery. The practical feasibility of MOFs is possible owing to their abilities for biodegradability, excellent porosity, high loading capacity, ease of surface modification, among others. In this regard, this review provides an account of various types of MOFs, their physiochemical characteristics and use in diverse disciplines of biomedical sciences - with special emphasis on drug delivery and theranostics. Moreover, this review also highlights the stability and toxicity issues of MOFs, along with their market potential for biomedical applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

Extremely durable biofouling-resistant metallic surfaces based on electrodeposited nanoporous tungstite films on steel

DOE PAGES

Tesler, Alexander B.; Kim, Philseok; Kolle, Stefan; ...

2015-10-20

Formation of unwanted deposits on steels during their interaction with liquids is an inherent problem that often leads to corrosion, biofouling and results in reduction in durability and function. Here we report a new route to form anti-fouling steel surfaces by electrodeposition of nanoporous tungsten oxide (TO) films. TO-modified steels are as mechanically durable as bare steel and highly tolerant to compressive and tensile stresses due to chemical bonding to the substrate and island-like morphology. When inherently superhydrophilic TO coatings are converted to superhydrophobic, they remain non-wetting even after impingement with yttria-stabilized-zirconia particles, or exposure to ultraviolet light and extrememore » temperatures. Upon lubrication, these surfaces display omniphobicity against highly contaminating media retaining hitherto unseen mechanical durability. Furthermore, to illustrate the applicability of such a durable coating in biofouling conditions, we modified naval construction steels and surgical instruments and demonstrated significantly reduced marine algal film adhesion, Escherichia coli attachment and blood staining.« less

High-flux water desalination with interfacial salt sieving effect in nanoporous carbon composite membranes

NASA Astrophysics Data System (ADS)

Chen, Wei; Chen, Shuyu; Liang, Tengfei; Zhang, Qiang; Fan, Zhongli; Yin, Hang; Huang, Kuo-Wei; Zhang, Xixiang; Lai, Zhiping; Sheng, Ping

2018-04-01

Freshwater flux and energy consumption are two important benchmarks for the membrane desalination process. Here, we show that nanoporous carbon composite membranes, which comprise a layer of porous carbon fibre structures grown on a porous ceramic substrate, can exhibit 100% desalination and a freshwater flux that is 3-20 times higher than existing polymeric membranes. Thermal accounting experiments demonstrated that the carbon composite membrane saved over 80% of the latent heat consumption. Theoretical calculations combined with molecular dynamics simulations revealed the unique microscopic process occurring in the membrane. When the salt solution is stopped at the openings to the nanoscale porous channels and forms a meniscus, the vapour can rapidly transport across the nanoscale gap to condense on the permeate side. This process is driven by the chemical potential gradient and aided by the unique smoothness of the carbon surface. The high thermal conductivity of the carbon composite membrane ensures that most of the latent heat is recovered.

Microstructure and Rheology of a Flow-Induced Structured Phase in Wormlike Micellar Solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cardiel Rivera, Joshua J.; Dohnalkova, Alice; Dubash, Neville

2013-04-30

Surfactant molecules found in soaps and detergents can self-assemble into a great variety of morphologies (e.g., spherical micelles, cylindrical micelles, and lamellar phases). The resulting morphology is highly affected by ionic strength, temperature, and flow conditions. In particular, cylindrical micelles in the presence of inorganic or organic salts can self-assemble into large flexible and elongated wormlike micelles. In equilibrium, the wormlike micelles transition from slightly entangled to branched and, finally, to multi-connected structures with increasing salt concentration. In our work, by introducing external flow conditions via microfluidics, these micellar structures can follow very different trajectories on the phase map andmore » new nanoporous structures can be created. This flow induced approach offers great potential to create novel materials and nanoporous scaffolds from wormlike micelles under ambient temperature and pressure, without any chemical and thermal means (1). As a result, this work provides attractive solutions for synthesizing new biocompatible materials under ambient conditions with biosensing, encapsulation, catalysis, photonics, and self-healing applications.« less

Synthesis of Dicyclopentadiene Oligomer Over Nanoporous Al-MCM-41 Catalysts.

PubMed

Park, Eunseo; Kim, Jinhan; Yim, Jin-Heong; Han, Jeongsik; Kwon, Tae Soo; Park, Y K; Jeon, Jong-Ki

2016-05-01

One step reaction composed of DCPD oligomerization and DCPD oligomer isomerization was investigated over nanoporous Al-MCM-41 catalysts. The effects of aluminum grafting over MCM-41 on the catalyst characteristics were studied with respect to the synthesis of TCPD isomer. Physical and chemical properties of the catalysts were analyzed by N2 adsorption, temperature-programmed desorption of ammonia, and infrared spectroscopy of adsorbed pyridine. The overall number of acid sites as well as the number of Lewis acid sites increased with increasing of aluminum content over MCM-41. When utilizing MCM-41 and Al-MCM-41 as the catalyst, DCPD oligomerization reaction activity greatly increased compared to the thermal reaction. The highest TCPD isomer selectivity over the Al-MCM-41 catalyst with the highest aluminum content could be ascribed to the largest amount of acid sites. This study showed an increased level of TCPD isomer selectivity by an increasing level of Lewis acid sites through aluminum addition over MCM-41.

Noise Properties of Rectifying Nanopores

DOE Office of Scientific and Technical Information (OSTI.GOV)

Powell, M R; Sa, N; Davenport, M

2011-02-18

Ion currents through three types of rectifying nanoporous structures are studied and compared for the first time: conically shaped polymer nanopores, glass nanopipettes, and silicon nitride nanopores. Time signals of ion currents are analyzed by power spectrum. We focus on the low-frequency range where the power spectrum magnitude scales with frequency, f, as 1/f. Glass nanopipettes and polymer nanopores exhibit non-equilibrium 1/f noise, thus the normalized power spectrum depends on the voltage polarity and magnitude. In contrast, 1/f noise in rectifying silicon nitride nanopores is of equilibrium character. Various mechanisms underlying the voltage-dependent 1/f noise are explored and discussed, includingmore » intrinsic pore wall dynamics, and formation of vortices and non-linear flow patterns in the pore. Experimental data are supported by modeling of ion currents based on the coupled Poisson-Nernst-Planck and Navier Stokes equations. We conclude that the voltage-dependent 1/f noise observed in polymer and glass asymmetric nanopores might result from high and asymmetric electric fields inducing secondary effects in the pore such as enhanced water dissociation.« less

Surface effects on ionic Coulomb blockade in nanometer-size pores

NASA Astrophysics Data System (ADS)

Tanaka, Hiroya; Iizuka, Hideo; Pershin, Yuriy V.; Di Ventra, Massimiliano

2018-01-01

Ionic Coulomb blockade in nanopores is a phenomenon that shares some similarities but also differences with its electronic counterpart. Here, we investigate this phenomenon extensively using all-atom molecular dynamics of ionic transport through nanopores of about one nanometer in diameter and up to several nanometers in length. Our goal is to better understand the role of atomic roughness and structure of the pore walls in the ionic Coulomb blockade. Our numerical results reveal the following general trends. First, the nanopore selectivity changes with its diameter, and the nanopore position in the membrane influences the current strength. Second, the ionic transport through the nanopore takes place in a hopping-like fashion over a set of discretized states caused by local electric fields due to membrane atoms. In some cases, this creates a slow-varying ‘crystal-like’ structure of ions inside the nanopore. Third, while at a given voltage, the resistance of the nanopore depends on its length, the slope of this dependence appears to be independent of the molarity of ions. An effective kinetic model that captures the ionic Coulomb blockade behavior observed in MD simulations is formulated.

Surface effects on ionic Coulomb blockade in nanometer-size pores.

PubMed

Tanaka, Hiroya; Iizuka, Hideo; Pershin, Yuriy V; Ventra, Massimiliano Di

2018-01-12

Ionic Coulomb blockade in nanopores is a phenomenon that shares some similarities but also differences with its electronic counterpart. Here, we investigate this phenomenon extensively using all-atom molecular dynamics of ionic transport through nanopores of about one nanometer in diameter and up to several nanometers in length. Our goal is to better understand the role of atomic roughness and structure of the pore walls in the ionic Coulomb blockade. Our numerical results reveal the following general trends. First, the nanopore selectivity changes with its diameter, and the nanopore position in the membrane influences the current strength. Second, the ionic transport through the nanopore takes place in a hopping-like fashion over a set of discretized states caused by local electric fields due to membrane atoms. In some cases, this creates a slow-varying 'crystal-like' structure of ions inside the nanopore. Third, while at a given voltage, the resistance of the nanopore depends on its length, the slope of this dependence appears to be independent of the molarity of ions. An effective kinetic model that captures the ionic Coulomb blockade behavior observed in MD simulations is formulated.

Synthetic Nanopores as a Test Case for Ion Channel Theories: The Anomalous Mole Fraction Effect without Single Filing

PubMed Central

Gillespie, Dirk; Boda, Dezső; He, Yan; Apel, Pavel; Siwy, Zuzanna S.

2008-01-01

The predictions of a theory for the anomalous mole fraction effect (AMFE) are tested experimentally with synthetic nanopores in plastic. The negatively charged synthetic nanopores under consideration are highly cation selective and 50 Å in diameter at their smallest point. These pores exhibit an AMFE in mixtures of Ca2+ and monovalent cations. An AMFE occurs when the conductance through a pore is lower in a mixture of salts than in the pure salts at the same concentration. For ion channels, the textbook interpretation of the AMFE is that multiple ions move through the pore in coordinated, single-file motion. However, because the synthetic nanopores are so wide, their AMFE shows that single filing is not necessary for the AMFE. It is shown that the AMFE in the synthetic nanopores is explained by a theory of preferential ion selectivity. The unique properties of the synthetic nanopores allow us to experimentally confirm several predictions of this theory. These same properties make synthetic nanopores an interesting new platform to test theories of ion channel permeation and selectivity in general. PMID:18390596

Anti-reflective nanoporous silicon for efficient hydrogen production

DOEpatents

Oh, Jihun; Branz, Howard M

2014-05-20

Exemplary embodiments are disclosed of anti-reflective nanoporous silicon for efficient hydrogen production by photoelectrolysis of water. A nanoporous black Si is disclosed as an efficient photocathode for H.sub.2 production from water splitting half-reaction.

Applications of Nanoporous Materials in Agriculture

USDA-ARS?s Scientific Manuscript database

Nanoporous materials possess organized pore distributions and increased surface areas. Advances in the systematic design of nanoporous materials enable incorporation of functionality for better sensitivity in detection methods, increased capacity of sorbents, and improved selectivity and yield in ca...

Nanoporous Ni with High Surface Area for Potential Hydrogen Storage Application.

PubMed

Zhou, Xiaocao; Zhao, Haibo; Fu, Zhibing; Qu, Jing; Zhong, Minglong; Yang, Xi; Yi, Yong; Wang, Chaoyang

2018-06-01

Nanoporous metals with considerable specific surface areas and hierarchical pore structures exhibit promising applications in the field of hydrogen storage, electrocatalysis, and fuel cells. In this manuscript, a facile method is demonstrated for fabricating nanoporous Ni with a high surface area by using SiO₂ aerogel as a template, i.e., electroless plating of Ni into an SiO₂ aerogel template followed by removal of the template at moderate conditions. The effects of the prepared conditions, including the electroless plating time, temperature of the structure, and the magnetism of nanoporous Ni are investigated in detail. The resultant optimum nanoporous Ni with a special 3D flower-like structure exhibited a high specific surface area of about 120.5 m²/g. The special nanoporous Ni exhibited a promising prospect in the field of hydrogen storage, with a hydrogen capacity of 0.45 wt % on 4.5 MPa at room temperature.

A Protein Nanopore-Based Approach for Bacteria Sensing

NASA Astrophysics Data System (ADS)

Apetrei, Aurelia; Ciuca, Andrei; Lee, Jong-kook; Seo, Chang Ho; Park, Yoonkyung; Luchian, Tudor

2016-11-01

We present herein a first proof of concept demonstrating the potential of a protein nanopore-based technique for real-time detection of selected Gram-negative bacteria ( Pseudomonas aeruginosa or Escherichia coli) at a concentration of 1.2 × 108 cfu/mL. The anionic charge on the bacterial outer membrane promotes the electrophoretically driven migration of bacteria towards a single α-hemolysin nanopore isolated in a lipid bilayer, clamped at a negative electric potential, and followed by capture at the nanopore's mouth, which we found to be described according to the classical Kramers' theory. By using a specific antimicrobial peptide as a putative molecular biorecognition element for the bacteria used herein, we suggest that the detection system can combine the natural sensitivity of the nanopore-based sensing techniques with selective biological recognition, in aqueous samples, and highlight the feasibility of the nanopore-based platform to provide portable, sensitive analysis and monitoring of bacterial pathogens.

Atomic layer deposition of TIO{sub 2} thin films on nanoporous alumina templates : medical applications.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Narayan, R. J.; Monteiro-Riviere, N. A.; Brigmon, R. L.

2009-06-01

Nanostructured materials may play a significant role in controlled release of pharmacologic agents for treatment of cancer. Many nanoporous polymer materials are inadequate for use in drug delivery. Nanoporous alumina provides several advantages over other materials for use in controlled drug delivery and other medical applications. Atomic layer deposition was used to coat all the surfaces of a nanoporous alumina membrane in order to reduce the pore size in a controlled manner. Neither the 20 nm nor the 100 nm TiO{sub 2}-coated nanoporous alumina membranes exhibited statistically lower viability compared to the uncoated nanoporous alumina membrane control materials. Nanostructured materialsmore » prepared using atomic layer deposition may be useful for delivering a pharmacologic agent at a precise rate to a specific location in the body. These materials may serve as the basis for 'smart' drug delivery devices, orthopedic implants, or self-sterilizing medical devices.« less

Balancing size exclusion and adsorption of polymers in nanopores

NASA Astrophysics Data System (ADS)

Kim, Won; Ryu, Chang Y.

2006-03-01

The liquid chromatography at critical condition (LCCC) presents the condition, at which the size exclusion and adsorption of polymer chains are balanced upon interactions with nanoporous substrates. In this study, we investigate how the polymer interactions with nanopores are affected by the solvent quality and nanopore size. Specifically, we measure the retention times of monodisperse polystyrenes in C18-bonded nanoporous silica column as a function of molecular weight, when a mixed solvent of methylene chloride and acetonitrile are used as elutent. C18-bonded silica particles with 70, 100, and 250 A pore size are used as a stationary phase to study how the transition from SEC-like to IC-like retention behavior depends on the condition of temperature and solvent composition. To locate the LCCC at various nanopore sizes, the temperature and solvent composition have been varied from 0 to 60 C and from 51 to 62 v/v% of methylene chloride, respectively.

Pre-breakdown cavitation nanopores in the dielectric fluid in the inhomogeneous, pulsed electric fields

NASA Astrophysics Data System (ADS)

Pekker, Mikhail; Shneider, Mikhail N.

2015-10-01

This paper discusses the nanopores emerging and developing in a liquid dielectric under the action of the ponderomotive electrostrictive forces in a nonuniform electric field. It is shown that the gradient of the electric field in the vicinity of the rupture (cavitation nanopore) substantially increases and determines whether the rupture grows or collapses. The cavitation rupture in the liquid (nanopore) tends to stretch along the lines of the original field. The mechanism of the breakdown associated with the generation of secondary ruptures in the vicinity of the poles of the nanopore is proposed. The estimations of the extension time for nanopore in water and oil (polar and nonpolar liquids, respectively) are presented. A new mechanism of nano- and subnanosecond breakdown in the insulating (transformer) oil that can be realized in the vicinity of water microdroplets in nanosecond high-voltage devices is considered.

Tailoring the hydrophobicity of graphene for its use as nanopores for DNA translocation

NASA Astrophysics Data System (ADS)

Schneider, Grégory F.; Xu, Qiang; Hage, Susanne; Luik, Stephanie; Spoor, Johannes N. H.; Malladi, Sairam; Zandbergen, Henny; Dekker, Cees

2013-10-01

Graphene nanopores are potential successors to biological and silicon-based nanopores. For sensing applications, it is however crucial to understand and block the strong nonspecific hydrophobic interactions between DNA and graphene. Here we demonstrate a novel scheme to prevent DNA-graphene interactions, based on a tailored self-assembled monolayer. For bare graphene, we encounter a paradox: whereas contaminated graphene nanopores facilitated DNA translocation well, clean crystalline graphene pores very quickly exhibit clogging of the pore. We attribute this to strong interactions between DNA nucleotides and graphene, yielding sticking and irreversible pore closure. We develop a general strategy to noncovalently tailor the hydrophobic surface of graphene by designing a dedicated self-assembled monolayer of pyrene ethylene glycol, which renders the surface hydrophilic. We demonstrate that this prevents DNA to adsorb on graphene and show that single-stranded DNA can now be detected in graphene nanopores with excellent nanopore durability and reproducibility.

Molecular-based design and emerging applications of nanoporous carbon spheres

NASA Astrophysics Data System (ADS)

Liu, Jian; Wickramaratne, Nilantha P.; Qiao, Shi Zhang; Jaroniec, Mietek

2015-08-01

Over the past decade, considerable progress has been made in the synthesis and applications of nanoporous carbon spheres ranging in size from nanometres to micrometres. This Review presents the primary techniques for preparing nanoporous carbon spheres and the seminal research that has inspired their development, presented potential applications and uncovered future challenges. First we provide an overview of the synthesis techniques, including the Stöber method and those based on templating, self-assembly, emulsion and hydrothermal carbonization, with special emphasis on the design and functionalization of nanoporous carbon spheres at the molecular level. Next, we cover the key applications of these spheres, including adsorption, catalysis, separation, energy storage and biomedicine -- all of which might benefit from the regular geometry, good liquidity, tunable porosity and controllable particle-size distribution offered by nanoporous carbon spheres. Finally, we present the current challenges and opportunities in the development and commercial applications of nanoporous carbon spheres.

Molecular-based design and emerging applications of nanoporous carbon spheres.

PubMed

Liu, Jian; Wickramaratne, Nilantha P; Qiao, Shi Zhang; Jaroniec, Mietek

2015-08-01

Over the past decade, considerable progress has been made in the synthesis and applications of nanoporous carbon spheres ranging in size from nanometres to micrometres. This Review presents the primary techniques for preparing nanoporous carbon spheres and the seminal research that has inspired their development, presented potential applications and uncovered future challenges. First we provide an overview of the synthesis techniques, including the Stöber method and those based on templating, self-assembly, emulsion and hydrothermal carbonization, with special emphasis on the design and functionalization of nanoporous carbon spheres at the molecular level. Next, we cover the key applications of these spheres, including adsorption, catalysis, separation, energy storage and biomedicine — all of which might benefit from the regular geometry, good liquidity, tunable porosity and controllable particle-size distribution offered by nanoporous carbon spheres. Finally, we present the current challenges and opportunities in the development and commercial applications of nanoporous carbon spheres.

Transport of Proteins through Nanopores

NASA Astrophysics Data System (ADS)

Luan, Binquan

In biological cells, a malfunctioned protein (such as misfolded or damaged) is degraded by a protease in which an unfoldase actively drags the protein into a nanopore-like structure and then a peptidase cuts the linearized protein into small fragments (i.e. a recycling process). Mimicking this biological process, many experimental studies have focused on the transport of proteins through a biological protein pore or a synthetic solid-state nanopore. Potentially, the nanopore-based sensors can provide a platform for interrogating proteins that might be disease-related or be targeted by a new drug molecule. The single-profile of a protein chain inside an extremely small nanopore might even permit the sequencing of the protein. Here, through all-atom molecular dynamics simulations, I will show various types of protein transport through a nanopore and reveal the nanoscale mechanics/energetics that plays an important role governing the protein transport.

Normal-incidence quantum cascade detector coupled by nanopore structure

NASA Astrophysics Data System (ADS)

Liu, Jianqi; Wang, Fengjiao; Zhai, Shenqiang; Zhang, Jinchuan; Liu, Shuman; Liu, Junqi; Wang, Lijun; Liu, Fengqi; Wang, Zhanguo

2018-04-01

A normal-incidence quantum cascade detector coupled by a nanopore array structure (NPS) is demonstrated. The NPS is fabricated on top of an In0.53Ga0.47As contact layer by inductively coupled plasma etching using anodic aluminum oxide as a mask. Because of the nonuniform volume fraction at different areas of the device mesa, the NPS acts as subwavelength random gratings. Normal-incidence light can be scattered into random oblique directions for inter-sub-band transition absorption. With normal incidence, the responsivities of the device reach 24 mA/W at 77 K and 15.7 mA/W at 300 K, which are enhanced 2.23 and 1.96 times, respectively, compared with that of the 45°-edge device.

Asymmetric ion transport through ion-channel-mimetic solid-state nanopores.

PubMed

Guo, Wei; Tian, Ye; Jiang, Lei

2013-12-17

Both scientists and engineers are interested in the design and fabrication of synthetic nanofluidic architectures that mimic the gating functions of biological ion channels. The effort to build such structures requires interdisciplinary efforts at the intersection of chemistry, materials science, and nanotechnology. Biological ion channels and synthetic nanofluidic devices have some structural and chemical similarities, and therefore, they share some common features in regulating the traverse ionic flow. In the past decade, researchers have identified two asymmetric ion transport phenomena in synthetic nanofluidic structures, the rectified ionic current and the net diffusion current. The rectified ionic current is a diode-like current-voltage response that occurs when switching the voltage bias. This phenomenon indicates a preferential direction of transport in the nanofluidic system. The net diffusion current occurs as a direct product of charge selectivity and is generated from the asymmetric diffusion through charged nanofluidic channels. These new ion transport phenomena and the elaborate structures that occur in biology have inspired us to build functional nanofluidic devices for both fundamental research and practical applications. In this Account, we review our recent progress in the design and fabrication of biomimetic solid-state nanofluidic devices with asymmetric ion transport behavior. We demonstrate the origin of the rectified ionic current and the net diffusion current. We also identify several influential factors and discuss how to build these asymmetric features into nanofluidic systems by controlling (1) nanopore geometry, (2) surface charge distribution, (3) chemical composition, (4) channel wall wettability, (5) environmental pH, (6) electrolyte concentration gradient, and (7) ion mobility. In the case of the first four features, we build these asymmetric features directly into the nanofluidic structures. With the final three, we construct different environmental conditions in the electrolyte solutions on either side of the nanochannel. The novel and well-controlled nanofluidic phenomena have become the foundation for many promising applications, and we have highlighted several representative examples. Inspired by the electrogenic cell of the electric eel, we have demonstrated a proof-of-concept nanofluidic reverse electrodialysis system (NREDS) that converts salinity gradient energy into electricity by means of net diffusion current. We have also constructed chirality analysis systems into nanofluidic architectures and monitored these sensing events as the change in the degree of ionic current rectification. Moreover, we have developed a biohybrid nanosystem, in which we reconstituted the F0F1-ATPase on a liposome-coated, solid-state nanoporous membrane. By applying a transmembrane proton concentration gradient, the biohybrid nanodevice can synthesize ATP in vitro. These findings have improved our understanding of the asymmetric ion transport phenomena in synthetic nanofluidic systems and offer innovative insights into the design of functional nanofluidic devices.

Capture, Unfolding, and Detection of Individual tRNA Molecules Using a Nanopore Device

PubMed Central

Smith, Andrew M.; Abu-Shumays, Robin; Akeson, Mark; Bernick, David L.

2015-01-01

Transfer RNAs (tRNA) are the most common RNA molecules in cells and have critical roles as both translators of the genetic code and regulators of protein synthesis. As such, numerous methods have focused on studying tRNA abundance and regulation, with the most widely used methods being RNA-seq and microarrays. Though revolutionary to transcriptomics, these assays are limited by an inability to encode tRNA modifications in the requisite cDNA. These modifications are abundant in tRNA and critical to their function. Here, we describe proof-of-concept experiments where individual tRNA molecules are examined as linear strands using a biological nanopore. This method utilizes an enzymatically ligated synthetic DNA adapter to concentrate tRNA at the lipid bilayer of the nanopore device and efficiently denature individual tRNA molecules, as they are pulled through the α-hemolysin (α-HL) nanopore. Additionally, the DNA adapter provides a loading site for ϕ29 DNA polymerase (ϕ29 DNAP), which acts as a brake on the translocating tRNA. This increases the dwell time of adapted tRNA in the nanopore, allowing us to identify the region of the nanopore signal that is produced by the translocating tRNA itself. Using adapter-modified Escherichia coli tRNAfMet and tRNALys, we show that the nanopore signal during controlled translocation is dependent on the identity of the tRNA. This confirms that adapter-modified tRNA can translocate end-to-end through nanopores and provide the foundation for future work in direct sequencing of individual transfer RNA with a nanopore-based device. PMID:26157798

Real-time single-molecule electronic DNA sequencing by synthesis using polymer-tagged nucleotides on a nanopore array

PubMed Central

Fuller, Carl W.; Kumar, Shiv; Porel, Mintu; Chien, Minchen; Bibillo, Arek; Stranges, P. Benjamin; Dorwart, Michael; Tao, Chuanjuan; Li, Zengmin; Guo, Wenjing; Shi, Shundi; Korenblum, Daniel; Trans, Andrew; Aguirre, Anne; Liu, Edward; Harada, Eric T.; Pollard, James; Bhat, Ashwini; Cech, Cynthia; Yang, Alexander; Arnold, Cleoma; Palla, Mirkó; Hovis, Jennifer; Chen, Roger; Morozova, Irina; Kalachikov, Sergey; Russo, James J.; Kasianowicz, John J.; Davis, Randy; Roever, Stefan; Church, George M.; Ju, Jingyue

2016-01-01

DNA sequencing by synthesis (SBS) offers a robust platform to decipher nucleic acid sequences. Recently, we reported a single-molecule nanopore-based SBS strategy that accurately distinguishes four bases by electronically detecting and differentiating four different polymer tags attached to the 5′-phosphate of the nucleotides during their incorporation into a growing DNA strand catalyzed by DNA polymerase. Further developing this approach, we report here the use of nucleotides tagged at the terminal phosphate with oligonucleotide-based polymers to perform nanopore SBS on an α-hemolysin nanopore array platform. We designed and synthesized several polymer-tagged nucleotides using tags that produce different electrical current blockade levels and verified they are active substrates for DNA polymerase. A highly processive DNA polymerase was conjugated to the nanopore, and the conjugates were complexed with primer/template DNA and inserted into lipid bilayers over individually addressable electrodes of the nanopore chip. When an incoming complementary-tagged nucleotide forms a tight ternary complex with the primer/template and polymerase, the tag enters the pore, and the current blockade level is measured. The levels displayed by the four nucleotides tagged with four different polymers captured in the nanopore in such ternary complexes were clearly distinguishable and sequence-specific, enabling continuous sequence determination during the polymerase reaction. Thus, real-time single-molecule electronic DNA sequencing data with single-base resolution were obtained. The use of these polymer-tagged nucleotides, combined with polymerase tethering to nanopores and multiplexed nanopore sensors, should lead to new high-throughput sequencing methods. PMID:27091962

Solvothermal synthesis of stable nanoporous polymeric bases-crystalline TiO2 nanocomposites: visible light active and efficient photocatalysts for water treatment

NASA Astrophysics Data System (ADS)

Liu, Fujian; Kong, Weiping; Wang, Liang; Noshadi, Iman; Zhang, Zhonghua; Qi, Chenze

2015-02-01

Visible light active and stable nanoporous polymeric base-crystalline TiO2 nanocomposites were solvothermally synthesized from in situ copolymerization of divinylbenzene (DVB) with 1-vinylimidazolate (VI) or 4-vinylpyridine (Py) in the presence of tetrabutyl titanate without the use of any other additives (PDVB-VI-TiO2-x, PDVB-Py-TiO2-x, where x stands for the molar ratio of TiO2 to VI or Py), which showed excellent activity with respect to catalyzing the degradation of organic pollutants of p-nitrophenol (PNP) and rhodamine-B (RhB). TEM and SEM images show that PDVB-VI-TiO2-x and PDVB-Py-TiO2-x have abundant nanopores, and TiO2 nanocrystals with a high degree of crystallinity were homogeneously embedded in the PDVB-VI-TiO2-x and PDVB-Py-TiO2-x, forming a stable ‘brick-and-mortar’ nanostructure. PDVB-VI and PDVB-Py supports act as the glue linking TiO2 nanocrystals to form nanopores and constraining the agglomeration of TiO2 nanocrystals. XPS spectra show evidence of unique interactions between TiO2 and basic sites in these samples. UV diffuse reflectance shows that PDVB-VI-TiO2-x and PDVB-Py-TiO2-x exhibit a unique response to visible light. Catalytic tests show that the PDVB-VI-TiO2-x and PDVB-Py-TiO2-x were active in catalyzing the degradation of PNP and RhB organic pollutants under visible light irradiation. The enhanced activities of the PDVB-VI-TiO2-x and PDVB-Py-TiO2-x were ascribed to synergistic effects between abundant nanopores and the unique optical adsorption of visible light in the samples.

Solvothermal synthesis of stable nanoporous polymeric bases-crystalline TiO2 nanocomposites: visible light active and efficient photocatalysts for water treatment.

PubMed

Liu, Fujian; Kong, Weiping; Wang, Liang; Noshadi, Iman; Zhang, Zhonghua; Qi, Chenze

2015-02-27

Visible light active and stable nanoporous polymeric base-crystalline TiO2 nanocomposites were solvothermally synthesized from in situ copolymerization of divinylbenzene (DVB) with 1-vinylimidazolate (VI) or 4-vinylpyridine (Py) in the presence of tetrabutyl titanate without the use of any other additives (PDVB-VI-TiO2-x, PDVB-Py-TiO2-x, where x stands for the molar ratio of TiO2 to VI or Py), which showed excellent activity with respect to catalyzing the degradation of organic pollutants of p-nitrophenol (PNP) and rhodamine-B (RhB). TEM and SEM images show that PDVB-VI-TiO2-x and PDVB-Py-TiO2-x have abundant nanopores, and TiO2 nanocrystals with a high degree of crystallinity were homogeneously embedded in the PDVB-VI-TiO2-x and PDVB-Py-TiO2-x, forming a stable 'brick-and-mortar' nanostructure. PDVB-VI and PDVB-Py supports act as the glue linking TiO2 nanocrystals to form nanopores and constraining the agglomeration of TiO2 nanocrystals. XPS spectra show evidence of unique interactions between TiO2 and basic sites in these samples. UV diffuse reflectance shows that PDVB-VI-TiO2-x and PDVB-Py-TiO2-x exhibit a unique response to visible light. Catalytic tests show that the PDVB-VI-TiO2-x and PDVB-Py-TiO2-x were active in catalyzing the degradation of PNP and RhB organic pollutants under visible light irradiation. The enhanced activities of the PDVB-VI-TiO2-x and PDVB-Py-TiO2-x were ascribed to synergistic effects between abundant nanopores and the unique optical adsorption of visible light in the samples.

Microwave-aided synthesis and applications of gold and nickel nanoporous metal foams

NASA Astrophysics Data System (ADS)

Lu, Zhifeng

In the field of nanoscience, nanoporous metal foams are a representative type of nanostructured materials, representing the ultimate form factor of a metal. They possess the hybrid properties of metal and nanoarchitectures, including the following properties such as good electrical and thermal conductivity, catalytic activity and high surface area, ultralow density, high strength-to-weight ratio. The outstanding properties bring the nanoporous metal foams to a wide range of applications, especially in the field of sensor system, energy storage and chemical catalyst. A new method of synthesis developed recently is presented for nanoporous metal foams of gold and nickel. The goal of this study is for the synthesis process of NMFs of and some applications in research and realistic life. Gold NMFs were produced by mixing gold chloride with ethylene glycol, ethanol, and reducing agent, and heating at 150 °C for 5 min with a CEM microwave. Both hydrazine and sodium borohydride were applied as the reducing agent for this redox reaction. Nickel NMFs were produced through the similar procedure with a little difference in the heating condition of 50 W, instead of 150 °C, with either hydrazine or sodium borohydride as the reducing agent. Gold NMFs were applied in surface-enhanced Raman spectroscopy (SERS) as a substrate. It is presented that with the presence of gold NMFs, the detection of the rhodamine 6G (R6G), a model analyte, can be enhanced significantly. The limit of detection for rhodamine 6G was found to be 5.2 x 10 -7 M in this research. Nickel NMFs was applied to degrade methyl orange (MO). An aqueous MO solution will turn nearly colorless after only 10 h of mixing with 0.025 g of nickel NMFs at room temperature under dark condition. In order to study the kinetics of the degradation reaction, MO solution with different initial concentration were used. This application of Ni NMFs is applicable as waste treatment of industrial water and to protect the environment.

Pore spanning lipid bilayers on silanised nanoporous alumina membranes

NASA Astrophysics Data System (ADS)

Md Jani, Abdul M.; Zhou, Jinwen; Nussio, Matthew R.; Losic, Dusan; Shapter, Joe G.; Voelcker, Nicolas H.

2008-12-01

The preparation of bilayer lipid membranes (BLMs) on solid surfaces is important for many studies probing various important biological phenomena including the cell barrier properties, ion-channels, biosensing, drug discovery and protein/ligand interactions. In this work we present new membrane platforms based on suspended BLMs on nanoporous anodic aluminium oxide (AAO) membranes. AAO membranes were prepared by electrochemical anodisation of aluminium foil in 0.3 M oxalic acid using a custom-built etching cell and applying voltage of 40 V, at 1oC. AAO membranes with controlled diameter of pores from 30 - 40 nm (top of membrane) and 60 -70 nm (bottom of membrane) were fabricated. Pore dimensions have been confirmed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). AAO membranes were chemically functionalised with 3-aminopropyltriethoxysilane (APTES). Confirmation of the APTES attachment to the AAO membrane was achieved by means of infrared spectroscopy, X-ray photoelectron spectroscopy and contact angle measurements. The Fourier transform infrared (FTIR) spectra of functionalised membranes show several peaks from 2800 to 3000 cm-1 which were assigned to symmetric and antisymmetric CH2 bands. XPS data of the membrane showed a distinct increase in C1s (285 eV), N1s (402 eV) and Si2p (102 eV) peaks after silanisation. The water contact angle of the functionalised membrane was 80o as compared to 20o for the untreated membrane. The formation of BLMs comprising dioleoyl-phosphatidylserine (DOPS) on APTESmodified AAO membranes was carried using the vesicle spreading technique. AFM imaging and force spectroscopy was used to characterise the structural and nanomechanical properties of the suspended membrane. This technique also confirmed the stability of bilayers on the nanoporous alumina support for several days. Fabricated suspended BLMs on nanoporous AAO hold promise for the construction of biomimetic membrane architectures with embedded transmembrane proteins.

Can ionophobic nanopores enhance the energy storage capacity of electric-double-layer capacitors containing nonaqueous electrolytes?

NASA Astrophysics Data System (ADS)

Lian, Cheng; Liu, Honglai; Henderson, Douglas; Wu, Jianzhong

2016-10-01

The ionophobicity effect of nanoporous electrodes on the capacitance and the energy storage capacity of nonaqueous-electrolyte supercapacitors is studied by means of the classical density functional theory (DFT). It has been hypothesized that ionophobic nanopores may create obstacles in charging, but they store energy much more efficiently than ionophilic pores. In this study, we find that, for both ionic liquids and organic electrolytes, an ionophobic pore exhibits a charging behavior different from that of an ionophilic pore, and that the capacitance-voltage curve changes from a bell shape to a two-hump camel shape when the pore ionophobicity increases. For electric-double-layer capacitors containing organic electrolytes, an increase in the ionophobicity of the nanopores leads to a higher capacity for energy storage. Without taking into account the effects of background screening, the DFT predicts that an ionophobic pore containing an ionic liquid does not enhance the supercapacitor performance within the practical voltage ranges. However, by using an effective dielectric constant to account for ion polarizability, the DFT predicts that, like an organic electrolyte, an ionophobic pore with an ionic liquid is also able to increase the energy stored when the electrode voltage is beyond a certain value. We find that the critical voltage for an enhanced capacitance in an ionic liquid is larger than that in an organic electrolyte. Our theoretical predictions provide further understanding of how chemical modification of porous electrodes affects the performance of supercapacitors. The authors are saddened by the passing of George Stell but are pleased to contribute this article in his memory. Some years ago, DH gave a talk at a Gordon Conference that contained an approximation that George had demonstrated previously to be in error in one of his publications. Rather than making this point loudly in the discussion, George politely, quietly, and privately pointed this out later. In 2002, DH shared a room with George at a conference in China. This is remembered fondly.

Brittle-to-ductile transition of lithiated silicon electrodes: Crazing to stable nanopore growth.

PubMed

Wang, Haoran; Wang, Xueju; Xia, Shuman; Chew, Huck Beng

2015-09-14

Using first principle calculations, we uncover the underlying mechanisms explaining the brittle-to-ductile transition of LixSi electrodes in lithium ion batteries with increasing Li content. We show that plasticity initiates at x = ∼ 0.5 with the formation of a craze-like network of nanopores separated by Si-Si bonds, while subsequent failure is still brittle-like with the breaking of Si-Si bonds. Transition to ductile behavior occurs at x ⩾ 1 due to the increased density of highly stretchable Li-Li bonds, which delays nanopore formation and stabilizes nanopore growth. Collapse of the nanopores during unloading of the LixSi alloys leads to significant strain recovery.

An overview on the characterization and mechanical behavior of nanoporous Gold

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hodge, A M; Hayes, J R; Caro, J A

2005-09-13

In this paper we present what we believe are the most pressing issues in understanding the mechanical behavior of nanoporous foams. We have postulated that a gold foam presents the best candidate for a systematic study of nanoporous foams since it can be synthesized with a wide range of ligaments sizes and densities. We have also conducted preliminary tests that demonstrate (a) Au foams have a fracture behavior dictated by the ligament size, and (b) nanoporous Au is a high yield strength material. Thus, we have demonstrated the potential in developing nanoporous foams as a new class of high yieldmore » strength/low density materials.« less

Nanopore fabrication and characterization by helium ion microscopy

NASA Astrophysics Data System (ADS)

Emmrich, D.; Beyer, A.; Nadzeyka, A.; Bauerdick, S.; Meyer, J. C.; Kotakoski, J.; Gölzhäuser, A.

2016-04-01

The Helium Ion Microscope (HIM) has the capability to image small features with a resolution down to 0.35 nm due to its highly focused gas field ionization source and its small beam-sample interaction volume. In this work, the focused helium ion beam of a HIM is utilized to create nanopores with diameters down to 1.3 nm. It will be demonstrated that nanopores can be milled into silicon nitride, carbon nanomembranes, and graphene with well-defined aspect ratio. To image and characterize the produced nanopores, helium ion microscopy and high resolution scanning transmission electron microscopy were used. The analysis of the nanopores' growth behavior allows inferring on the profile of the helium ion beam.

Thermal Conductivity in Nanoporous Gold Films during Electron-Phonon Nonequilibrium

DOE PAGES

Hopkins, Patrick E.; Norris, Pamela M.; Phinney, Leslie M.; ...

2008-01-01

The reduction of nanodevices has given recent attention to nanoporous materials due to their structure and geometry. However, the thermophysical properties of these materials are relatively unknown. In this article, an expression for thermal conductivity of nanoporous structures is derived based on the assumption that the finite size of the ligaments leads to electron-ligament wall scattering. This expression is then used to analyze the thermal conductivity of nanoporous structures in the event of electron-phonon nonequilibrium.

Signal and Noise in FET-Nanopore Devices.

PubMed

Parkin, William M; Drndić, Marija

2018-02-23

The combination of a nanopore with a local field-effect transistor (FET-nanopore), like a nanoribbon, nanotube, or nanowire, in order to sense single molecules translocating through the pore is promising for DNA sequencing at megahertz bandwidths. Previously, it was experimentally determined that the detection mechanism was due to local potential fluctuations that arise when an analyte enters a nanopore and constricts ion flow through it, rather than the theoretically proposed mechanism of direct charge coupling between the DNA and nanowire. However, there has been little discussion on the experimentally observed detection mechanism and its relation to the operation of real devices. We model the intrinsic signal and noise in such an FET-nanopore device and compare the results to the ionic current signal. The physical dimensions of DNA molecules limit the change in gate voltage on the FET to below 40 mV. We discuss the low-frequency flicker noise (<10 kHz), medium-frequency thermal noise (<100 kHz), and high-frequency capacitive noise (>100 kHz) in FET-nanopore devices. At bandwidths dominated by thermal noise, the signal-to-noise ratio in FET-nanopore devices is lower than in the ionic current signal. At high frequencies, where noise due to parasitic capacitances in the amplifier and chip is the dominant source of noise in ionic current measurements, high-transconductance FET-nanopore devices can outperform ionic current measurements.

Ultrasonic modification of carbon materials for electrochemical capacitors.

PubMed

Rachiy, Bogdan I; Nykoliuk, Marian O; Budzulyak, Ivan M; Kachmar, Andrii I

2017-12-01

The paper is devoted to study the ultrasonic impact on the biomass of natural raw materials, which were used for the creation a nanoporous carbon material (NCM), which was used as electrode material for electrochemical capacitors (EC). The dry shells of apricot seeds were a feedstock, which were modified by the chemical treatment in the phosphoric acid and part of them were impacted by ultrasonic waves for 25 minutes. The NCM, which were obtained by carbonization at 550 °C, were modified by chemical treatment in the nitric acid. Thus, the different of modification NCM was obtained to compare their capacitance characteristics for EC. From experimental data we can do a conclusion, that ultrasonic modification and chemical treatment in nitric acidare improvecapacitance characteristics of NCM for EC.

Effect of various de-anodizing techniques on the surface stability of non-colored and colored nanoporous AAO films in acidic solution

NASA Astrophysics Data System (ADS)

Awad, Ahmed M.; Shehata, Omnia S.; Heakal, Fakiha El-Taib

2015-12-01

Anodic aluminum oxide (AAO) is well known as an important nanostructured material, and a useful template in the fabrication of nanostructures. Nanoporous anodic alumina (PAA) with high open porosity was prepared by adopting three de-anodizing regimes following the first anodizing step and preceding the second one. The de-anodizing methods include electrolytic etching (EE) and chemical etching using either phosphoric acid (PE) or sodium hydroxide (HE) solutions. Three of the obtained AAO samples were black colored by electrodeposition of copper nanoparticles in their pores. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques were used to characterize the electrochemical performance of the two sets of the prepared samples. In general, the data obtained in aggressive aerated 0.5 M HCl solution demonstrated dissimilar behavior for the three prepared samples despite that the second anodizing step was the same for all of them. The data indicated that the resistance and thickness of the inner barrier part of nano-PAA film, are the main controlling factors determining its stability. On the other hand, coloring the film decreased its stability due to the galvanic effect. The difference in the electrochemical behavior of the three colored samples was discussed based on the difference in both the pore size and thickness of the outer porous part of PAA film as supported by SEM, TEM and cross-sectional micrographs. These results can thus contribute for better engineering applications of nanoporous AAO.

A facile one-pot oxidation-assisted dealloying protocol to massively synthesize monolithic core-shell architectured nanoporous copper@cuprous oxide nanonetworks for photodegradation of methyl orange

PubMed Central

Liu, Wenbo; Chen, Long; Dong, Xin; Yan, Jiazhen; Li, Ning; Shi, Sanqiang; Zhang, Shichao

2016-01-01

In this report, a facile and effective one-pot oxidation-assisted dealloying protocol has been developed to massively synthesize monolithic core-shell architectured nanoporous copper@cuprous oxide nanonetworks (C-S NPC@Cu2O NNs) by chemical dealloying of melt-spun Al 37 at.% Cu alloy in an oxygen-rich alkaline solution at room temperature, which possesses superior photocatalytic activity towards photodegradation of methyl orange (MO). The experimental results show that the as-prepared nanocomposite exhibits an open, bicontinuous interpenetrating ligament-pore structure with length scales of 20 ± 5 nm, in which the ligaments comprising Cu and Cu2O are typical of core-shell architecture with uniform shell thickness of ca. 3.5 nm. The photodegradation experiments of C-S NPC@Cu2O NNs show their superior photocatalytic activities for the MO degradation under visible light irradiation with degradation rate as high as 6.67 mg min−1 gcat−1, which is a diffusion-controlled kinetic process in essence in light of the good linear correlation between photodegradation ratio and square root of irradiation time. The excellent photocatalytic activity can be ascribed to the synergistic effects between unique core-shell architecture and 3D nanoporous network with high specific surface area and fast mass transfer channel, indicating that the C-S NPC@Cu2O NNs will be a promising candidate for photocatalysts of MO degradation. PMID:27830720

A controllable molecular sieve for Na+ and K+ ions.

PubMed

Gong, Xiaojing; Li, Jichen; Xu, Ke; Wang, Jianfeng; Yang, Hui

2010-02-17

The selective rate of specific ion transport across nanoporous material is critical to biological and nanofluidic systems. Molecular sieves for ions can be achieved by steric and electrical effects. However, the radii of Na(+) and K(+) are quite similar; they both carry a positive charge, making them difficult to separate. Biological ionic channels contain precisely arranged arrays of amino acids that can efficiently recognize and guide the passage of K(+) or Na(+) across the cell membrane. However, the design of inorganic channels with novel recognition mechanisms that control the ionic selectivity remains a challenge. We present here a design for a controllable ion-selective nanopore (molecular sieve) based on a single-walled carbon nanotube with specially arranged carbonyl oxygen atoms modified inside the nanopore, which was inspired by the structure of potassium channels in membrane spanning proteins (e.g., KcsA). Our molecular dynamics simulations show that the remarkable selectivity is attributed to the hydration structure of Na(+) or K(+) confined in the nanochannels, which can be precisely tuned by different patterns of the carbonyl oxygen atoms. The results also suggest that a confined environment plays a dominant role in the selectivity process. These studies provide a better understanding of the mechanism of ionic selectivity in the KcsA channel and possible technical applications in nanotechnology and biotechnology, including serving as a laboratory-in-nanotube for special chemical interactions and as a high-efficiency nanodevice for purification or desalination of sea and brackish water.

Recent advances in functionalized micro and mesoporous carbon materials: synthesis and applications.

PubMed

Benzigar, Mercy R; Talapaneni, Siddulu Naidu; Joseph, Stalin; Ramadass, Kavitha; Singh, Gurwinder; Scaranto, Jessica; Ravon, Ugo; Al-Bahily, Khalid; Vinu, Ajayan

2018-04-23

Functionalized nanoporous carbon materials have attracted the colossal interest of the materials science fraternity owing to their intriguing physical and chemical properties including a well-ordered porous structure, exemplary high specific surface areas, electronic and ionic conductivity, excellent accessibility to active sites, and enhanced mass transport and diffusion. These properties make them a special and unique choice for various applications in divergent fields such as energy storage batteries, supercapacitors, energy conversion fuel cells, adsorption/separation of bulky molecules, heterogeneous catalysts, catalyst supports, photocatalysis, carbon capture, gas storage, biomolecule detection, vapour sensing and drug delivery. Because of the anisotropic and synergistic effects arising from the heteroatom doping at the nanoscale, these novel materials show high potential especially in electrochemical applications such as batteries, supercapacitors and electrocatalysts for fuel cell applications and water electrolysis. In order to gain the optimal benefit, it is necessary to implement tailor made functionalities in the porous carbon surfaces as well as in the carbon skeleton through the comprehensive experimentation. These most appealing nanoporous carbon materials can be synthesized through the carbonization of high carbon containing molecular precursors by using soft or hard templating or non-templating pathways. This review encompasses the approaches and the wide range of methodologies that have been employed over the last five years in the preparation and functionalisation of nanoporous carbon materials via incorporation of metals, non-metal heteroatoms, multiple heteroatoms, and various surface functional groups that mostly dictate their place in a wide range of practical applications.

Giant increase in the metal-enhanced fluorescence of organic molecules in nanoporous alumina templates and large molecule-specific red/blue-shift of the fluorescence peak.

PubMed

Sarkar, S; Kanchibotla, B; Nelson, J D; Edwards, J D; Anderson, J; Tepper, G C; Bandyopadhyay, S

2014-10-08

The fluorescence of organic fluorophore molecules is enhanced when they are placed in contact with certain metals (Al, Ag, Cu, Au, etc.) whose surface plasmon waves couple into the radiative modes of the molecules and increase the radiative efficiency. Here, we report a hitherto unknown size dependence of this metal-enhanced fluorescence (MEF) effect in the nanoscale. When the molecules are deposited in nanoporous anodic alumina films with exposed aluminum at the bottom of the pores, they form organic nanowires standing on aluminum nanoparticles whose plasmon waves have much larger amplitudes. This increases the MEF strongly, resulting in several orders of magnitude increase in the fluorescence intensity of the organic fluorophores. The increase in intensity shows an inverse superlinear dependence on nanowire diameter because the nanowires also act as plasmonic "waveguides" that concentrate the plasmons and increase the coupling of the plasmons with the radiative modes of the molecules. Furthermore, if the nanoporous template housing the nanowires has built-in electric fields due to space charges, a strong molecule-specific red- or blue-shift is induced in the fluorescence peak owing to a renormalization of the dipole moment of the molecule. This can be exploited to detect minute amounts of target molecules in a mixture using their optical signature (fluorescence) despite the presence of confounding background signals. It can result in a unique new technology for biosensing and chemical sensing.

A facile one-pot oxidation-assisted dealloying protocol to massively synthesize monolithic core-shell architectured nanoporous copper@cuprous oxide nanonetworks for photodegradation of methyl orange

NASA Astrophysics Data System (ADS)

Liu, Wenbo; Chen, Long; Dong, Xin; Yan, Jiazhen; Li, Ning; Shi, Sanqiang; Zhang, Shichao

2016-11-01

In this report, a facile and effective one-pot oxidation-assisted dealloying protocol has been developed to massively synthesize monolithic core-shell architectured nanoporous copper@cuprous oxide nanonetworks (C-S NPC@Cu2O NNs) by chemical dealloying of melt-spun Al 37 at.% Cu alloy in an oxygen-rich alkaline solution at room temperature, which possesses superior photocatalytic activity towards photodegradation of methyl orange (MO). The experimental results show that the as-prepared nanocomposite exhibits an open, bicontinuous interpenetrating ligament-pore structure with length scales of 20 ± 5 nm, in which the ligaments comprising Cu and Cu2O are typical of core-shell architecture with uniform shell thickness of ca. 3.5 nm. The photodegradation experiments of C-S NPC@Cu2O NNs show their superior photocatalytic activities for the MO degradation under visible light irradiation with degradation rate as high as 6.67 mg min-1 gcat-1, which is a diffusion-controlled kinetic process in essence in light of the good linear correlation between photodegradation ratio and square root of irradiation time. The excellent photocatalytic activity can be ascribed to the synergistic effects between unique core-shell architecture and 3D nanoporous network with high specific surface area and fast mass transfer channel, indicating that the C-S NPC@Cu2O NNs will be a promising candidate for photocatalysts of MO degradation.

Photophysics and energy transfer studies of Alq3 confined in the voids of nanoporous anodic alumina.

PubMed

Mohammadpour, Arash; Utkin, Ilya; Bodepudi, Srikrishna Chanakya; Kar, Piyush; Fedosejevs, Robert; Pramanik, Sandipan; Shankar, Karthik

2013-04-01

We report on a hierarchical nanoarchitecture wherein distinct chromophores are deterministically placed at two different types of sites in a nanoporous metal oxide framework. One chromophore, namely Tris(8-hydroxyquinoline)aluminium(III) (Alq3), is embedded in the 1-2 nm sized nanovoids of anodic aluminum oxide (AAO) and another chromophore (carboxyfluorescein or pyrenebutyric acid) is anchored in the form of a monolayer to the surface of the walls of the cylindrical nanopores (- 20 nm in diameter) of AAO. We found the luminescence maximum to occur at 492 nm, blueshifted by at least 18 nm from the value in solutions and thin films. The excited state decay of Alq3 molecules in nanovoids was found to be biexponential with a fast component of 338 ps and a slower component of 2.26 ns, different from Alq3 thin films and solutions. Using a combination of steady state and time-resolved luminescence studies, we found that efficient Forster-type resonance energy transfer (FRET) from Alq3 in the nanovoids to the carboxyfluorescein monolayer could be used to pump the emission of surface-bound chromophores. Conversely, the emission of nanovoid-confined Alq3 could be pumped by energy transfer from a pyrenebutyric acid monolayer. Such intra-nanoarchitecture interactions between chromophores deterministically placed in different spatial locations are important in applications such as organic light emitting diodes, chemical sensors, energy transfer fluorescent labels, light harvesting antennas and organic spintronics.

Integration of solid-state nanopores in a 0.5 μm CMOS foundry process.

PubMed

Uddin, A; Yemenicioglu, S; Chen, C-H; Corigliano, E; Milaninia, K; Theogarajan, L

2013-04-19

High-bandwidth and low-noise nanopore sensor and detection electronics are crucial in achieving single-DNA-base resolution. A potential way to accomplish this goal is to integrate solid-state nanopores within a CMOS platform, in close proximity to the biasing electrodes and custom-designed amplifier electronics. Here we report the integration of solid-state nanopore devices in a commercial complementary metal-oxide-semiconductor (CMOS) potentiostat chip implemented in On-Semiconductor's 0.5 μm technology. Nanopore membranes incorporating electrodes are fabricated by post-CMOS micromachining utilizing the n+ polysilicon/SiO2/n+ polysilicon capacitor structure available in the aforementioned process. Nanopores are created in the CMOS process by drilling in a transmission electron microscope and shrinking by atomic layer deposition. We also describe a batch fabrication method to process a large of number of electrode-embedded nanopores with sub-10 nm diameter across CMOS-compatible wafers by electron beam lithography and atomic layer deposition. The CMOS-compatibility of our fabrication process is verified by testing the electrical functionality of on-chip circuitry. We observe high current leakage with the CMOS nanopore devices due to the ionic diffusion through the SiO2 membrane. To prevent this leakage, we coat the membrane with Al2O3, which acts as an efficient diffusion barrier against alkali ions. The resulting nanopore devices also exhibit higher robustness and lower 1/f noise as compared to SiO2 and SiNx. Furthermore, we propose a theoretical model for our low-capacitance CMOS nanopore devices, showing good agreement with the experimental value. In addition, experiments and theoretical models of translocation studies are presented using 48.5 kbp λ-DNA in order to prove the functionality of on-chip pores coated with Al2O3.

Streaming current magnetic fields in a charged nanopore.

PubMed

Mansouri, Abraham; Taheri, Peyman; Kostiuk, Larry W

2016-11-11

Magnetic fields induced by currents created in pressure driven flows inside a solid-state charged nanopore were modeled by numerically solving a system of steady state continuum partial differential equations, i.e., Poisson, Nernst-Planck, Ampere and Navier-Stokes equations (PNPANS). This analysis was based on non-dimensional transport governing equations that were scaled using Debye length as the characteristic length scale, and applied to a finite length cylindrical nano-channel. The comparison of numerical and analytical studies shows an excellent agreement and verified the magnetic fields density both inside and outside the nanopore. The radially non-uniform currents resulted in highly non-uniform magnetic fields within the nanopore that decay as 1/r outside the nanopore. It is worth noting that for either streaming currents or streaming potential cases, the maximum magnetic field occurred inside the pore in the vicinity of nanopore wall, as opposed to a cylindrical conductor that carries a steady electric current where the maximum magnetic fields occur at the perimeter of conductor. Based on these results, it is suggested and envisaged that non-invasive external magnetic fields readouts generated by streaming/ionic currents may be viewed as secondary electronic signatures of biomolecules to complement and enhance current DNA nanopore sequencing techniques.

Simultaneous Ionic Current and Potential Detection of Nanoparticles by a Multifunctional Nanopipette.

PubMed

Panday, Namuna; Qian, Gongming; Wang, Xuewen; Chang, Shuai; Pandey, Popular; He, Jin

2016-12-27

Nanopore sensing-based technologies have made significant progress for single molecule and single nanoparticle detection and analysis. In recent years, multimode sensing by multifunctional nanopores shows the potential to greatly improve the sensitivity and selectivity of traditional resistive-pulse sensing methods. In this paper, we showed that two label-free electric sensing modes could work cooperatively to detect the motion of 40 nm diameter spherical gold nanoparticles (GNPs) in solution by a multifunctional nanopipette. The multifunctional nanopipettes containing both nanopore and nanoelectrode (pyrolytic carbon) at the tip were fabricated quickly and cheaply. We demonstrated that the ionic current and local electrical potential changes could be detected simultaneously during the translocation of individual GNPs. We also showed that the nanopore/CNE tip geometry enabled the CNE not only to detect the translocation of single GNP but also to collectively detect several GNPs outside the nanopore entrance. The dynamic accumulation of GNPs near the nanopore entrance resulted in no detectable current changes, but was detected by the potential changes at the CNE. We revealed the motions of GNPs both outside and inside the nanopore, individually and collectively, with the combination of ionic current and potential measurements.

Detecting the Length of Double-stranded DNA with Solid State Nanopores

NASA Astrophysics Data System (ADS)

Li, Jiali; Gershow, Marc; Stein, Derek; Qun, Cai; Brandin, Eric; Wang, Hui; Huang, Albert; Branton, Dan; Golovchenko, Jene

2003-03-01

We report on the use of nanometer scale diameter, solid-state nanopores as single molecule detectors of double stranded DNA molecules. These solid-state nanopores are fabricated in thin membranes of silicon nitride, by ion beam sculpting 1. They produce discrete electronic signals: current blockages, when an electrically biased nanopore is exposed to DNA molecules in aqueous salt solutions. We demonstrate examples of such electronic signals for 3k base pairs (bp) and 10k bp double stranded DNA molecules, which suggest that these molecules are individually translocating through the nanopore during the detection process. The translocating time for the 10k bp double stranded DNA is about 3 times longer than the 3k bp, demonstrating that a solid-state nanopore device can be used to detect the lengths of double stranded DNA molecules. Similarities and differences with signals obtained from single stranded DNA in a biological nanopores are discussed 2. 1. Li, J., Stein, D., McMullan, C., Branton, D. Aziz, M. J. and Golovchenko, J. Ion Beam Sculpting at nanometer length scales. Nature 412, 166-169 (2001). 2. Meller, A., L. Nivon, E. Brandin, Golovchenko, J. & Branton, D. Proc. Natl. Acad. Sci. USA 97, 1079-1084 (2000).

Streaming current magnetic fields in a charged nanopore

NASA Astrophysics Data System (ADS)

Mansouri, Abraham; Taheri, Peyman; Kostiuk, Larry W.

2016-11-01

Magnetic fields induced by currents created in pressure driven flows inside a solid-state charged nanopore were modeled by numerically solving a system of steady state continuum partial differential equations, i.e., Poisson, Nernst-Planck, Ampere and Navier-Stokes equations (PNPANS). This analysis was based on non-dimensional transport governing equations that were scaled using Debye length as the characteristic length scale, and applied to a finite length cylindrical nano-channel. The comparison of numerical and analytical studies shows an excellent agreement and verified the magnetic fields density both inside and outside the nanopore. The radially non-uniform currents resulted in highly non-uniform magnetic fields within the nanopore that decay as 1/r outside the nanopore. It is worth noting that for either streaming currents or streaming potential cases, the maximum magnetic field occurred inside the pore in the vicinity of nanopore wall, as opposed to a cylindrical conductor that carries a steady electric current where the maximum magnetic fields occur at the perimeter of conductor. Based on these results, it is suggested and envisaged that non-invasive external magnetic fields readouts generated by streaming/ionic currents may be viewed as secondary electronic signatures of biomolecules to complement and enhance current DNA nanopore sequencing techniques.

Nanopore arrays in a silicon membrane for parallel single-molecule detection: DNA translocation

NASA Astrophysics Data System (ADS)

Zhang, Miao; Schmidt, Torsten; Jemt, Anders; Sahlén, Pelin; Sychugov, Ilya; Lundeberg, Joakim; Linnros, Jan

2015-08-01

Optical nanopore sensing offers great potential in single-molecule detection, genotyping, or DNA sequencing for high-throughput applications. However, one of the bottle-necks for fluorophore-based biomolecule sensing is the lack of an optically optimized membrane with a large array of nanopores, which has large pore-to-pore distance, small variation in pore size and low background photoluminescence (PL). Here, we demonstrate parallel detection of single-fluorophore-labeled DNA strands (450 bps) translocating through an array of silicon nanopores that fulfills the above-mentioned requirements for optical sensing. The nanopore array was fabricated using electron beam lithography and anisotropic etching followed by electrochemical etching resulting in pore diameters down to ∼7 nm. The DNA translocation measurements were performed in a conventional wide-field microscope tailored for effective background PL control. The individual nanopore diameter was found to have a substantial effect on the translocation velocity, where smaller openings slow the translocation enough for the event to be clearly detectable in the fluorescence. Our results demonstrate that a uniform silicon nanopore array combined with wide-field optical detection is a promising alternative with which to realize massively-parallel single-molecule detection.

Impact of the De-Alloying Kinetics and Alloy Microstructure on the Final Morphology of De-Alloyed Meso-Porous Metal Films

PubMed Central

Lin, Bao; Kong, Lingxue; Hodgson, Peter D.; Dumée, Ludovic F.

2014-01-01

Nano-textured porous metal materials present unique surface properties due to their enhanced surface energy with potential applications in sensing, molecular separation and catalysis. In this paper, commercial alloy foils, including brass (Cu85Zn15 and Cu70Zn30) and white gold (Au50Ag50) foils have been chemically de-alloyed to form nano-porous thin films. The impact of the initial alloy micro-structure and number of phases, as well as chemical de-alloying (DA) parameters, including etchant concentration, time and solution temperature on the final nano-porous thin film morphology and properties were investigated by electron microscopy (EM). Furthermore, the penetration depth of the pores across the alloys were evaluated through the preparation of cross sections by focus ion beam (FIB) milling. It is demonstrated that ordered pores ranging between 100 nm and 600 nm in diameter and 2–5 μm in depth can be successfully formed for the range of materials tested. The microstructure of the foils were obtained by electron back-scattered diffraction (EBSD) and linked to development of pits across the material thickness and surface during DA. The role of selective etching of both noble and sacrificial metal phases of the alloy were discussed in light of the competitive surface etching across the range of microstructures and materials tested. PMID:28344253

Nanoporous polymer electrolyte

DOEpatents

Elliott, Brian [Wheat Ridge, CO; Nguyen, Vinh [Wheat Ridge, CO

2012-04-24

A nanoporous polymer electrolyte and methods for making the polymer electrolyte are disclosed. The polymer electrolyte comprises a crosslinked self-assembly of a polymerizable salt surfactant, wherein the crosslinked self-assembly includes nanopores and wherein the crosslinked self-assembly has a conductivity of at least 1.0.times.10.sup.-6 S/cm at 25.degree. C. The method of making a polymer electrolyte comprises providing a polymerizable salt surfactant. The method further comprises crosslinking the polymerizable salt surfactant to form a nanoporous polymer electrolyte.

Computational modeling and analysis of thermoelectric properties of nanoporous silicon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, H.; Yu, Y.; Li, G., E-mail: gli@clemson.edu

2014-03-28

In this paper, thermoelectric properties of nanoporous silicon are modeled and studied by using a computational approach. The computational approach combines a quantum non-equilibrium Green's function (NEGF) coupled with the Poisson equation for electrical transport analysis, a phonon Boltzmann transport equation (BTE) for phonon thermal transport analysis and the Wiedemann-Franz law for calculating the electronic thermal conductivity. By solving the NEGF/Poisson equations self-consistently using a finite difference method, the electrical conductivity σ and Seebeck coefficient S of the material are numerically computed. The BTE is solved by using a finite volume method to obtain the phonon thermal conductivity k{sub p}more » and the Wiedemann-Franz law is used to obtain the electronic thermal conductivity k{sub e}. The figure of merit of nanoporous silicon is calculated by ZT=S{sup 2}σT/(k{sub p}+k{sub e}). The effects of doping density, porosity, temperature, and nanopore size on thermoelectric properties of nanoporous silicon are investigated. It is confirmed that nanoporous silicon has significantly higher thermoelectric energy conversion efficiency than its nonporous counterpart. Specifically, this study shows that, with a n-type doping density of 10{sup 20} cm{sup –3}, a porosity of 36% and nanopore size of 3 nm × 3 nm, the figure of merit ZT can reach 0.32 at 600 K. The results also show that the degradation of electrical conductivity of nanoporous Si due to the inclusion of nanopores is compensated by the large reduction in the phonon thermal conductivity and increase of absolute value of the Seebeck coefficient, resulting in a significantly improved ZT.« less

Nanopore-based fourth-generation DNA sequencing technology.

PubMed

Feng, Yanxiao; Zhang, Yuechuan; Ying, Cuifeng; Wang, Deqiang; Du, Chunlei

2015-02-01

Nanopore-based sequencers, as the fourth-generation DNA sequencing technology, have the potential to quickly and reliably sequence the entire human genome for less than $1000, and possibly for even less than $100. The single-molecule techniques used by this technology allow us to further study the interaction between DNA and protein, as well as between protein and protein. Nanopore analysis opens a new door to molecular biology investigation at the single-molecule scale. In this article, we have reviewed academic achievements in nanopore technology from the past as well as the latest advances, including both biological and solid-state nanopores, and discussed their recent and potential applications. Copyright © 2015 The Authors. Production and hosting by Elsevier Ltd.. All rights reserved.

Coordinative nanoporous polymers synthesized with hydrogen-bonded columnar liquid crystals.

PubMed

Ishihara, Shinsuke; Furuki, Yusuke; Hill, Jonathan P; Ariga, Katsuhiko; Takeoka, Shinji

2012-10-01

In this paper, we report the development of nanoporous polymer which demonstrates the coordination property toward zinc porphyrin. A hydrogen-bonded columnar liquid crystalline precursor composed of a triphenylene template and three equivalent of the surrounding dendric amphiphile bearing a pyridyl head group and a polymerizable aliphatic chain, was covalently fixed by photopolymerization, and then the subsequent selective removal of the template successively resulted in a nanoporous polymer in which the pore wall is modified with pyridyl groups. The nanoporous polymer reflected the conformation of template, and displayed considerable coordination ability of the pyridyl groups towards zinc porphyrin. The coordinative nanoporous polymer is promising as a nano-scaled scaffold for the organization of dyes into functional supramolecular architectures.

Aptamer-Encoded Nanopore for Ultrasensitive Detection of Bioterrorist Agent Ricin at Single-Molecule Resolution

PubMed Central

Gu, Li-Qun; Ding, Shu; Gao, Changlu

2011-01-01

The molecular-scale pore structure, called nanopore, can be formed from protein ion channels by genetic engineering or fabricated on solid substrates using fashion nanotechnology. Target molecules in interaction with the functionalized lumen of nanopore, can produce characteristic changes in the pore conductance, which act as fingerprints, allowing us to identify single molecules and simultaneously quantify each target species in the mixture. Nanopore sensors have been created for tremendous biomedical detections, with targets ranging from metal ions, drug compounds and cellular second messengers, to proteins and DNAs. Here we will review our recent discoveries with a lab-in-hand glass nanopore: single-molecule discrimination of chiral enantiomers with a trapped cyclodextrin, and sensing of bioterrorist agent ricin. PMID:19964179

Fabrication and characterization of a solid state nanopore with self-aligned carbon nanoelectrodes for molecular detection

NASA Astrophysics Data System (ADS)

Spinney, Patrick; Collins, Scott D.; Howitt, David G.; Smith, Rosemary L.

2012-06-01

Rapid and cost-effective DNA sequencing is a pivotal prerequisite for the genomics era. Many of the recent advances in forensics, medicine, agriculture, taxonomy, and drug discovery have paralleled critical advances in DNA sequencing technology. Nanopore modalities for DNA sequencing have recently surfaced including the electrical interrogation of protein ion channels and/or solid-state nanopores during translocation of DNA. However to date, most of this work has met with mixed success. In this work, we present a unique nanofabrication strategy that realizes an artificial nanopore articulated with carbon electrodes to sense the current modulations during the transport of DNA through the nanopore. This embodiment overcomes most of the technical difficulties inherent in other artificial nanopore embodiments and present a versatile platform for the testing of DNA single nucleotide detection. Characterization of the device using gold nanoparticles, silica nanoparticles, lambda dsDNA and 16-mer ssDNA are presented. Although single molecule DNA sequencing is still not demonstrated, the device shows a path towards this goal.

Redox behavior of uranium at the nanoporous aluminum oxide-water interface: implications for uranium remediation.

PubMed

Jung, Hun Bok; Boyanov, Maxim I; Konishi, Hiromi; Sun, Yubing; Mishra, Bhoopesh; Kemner, Kenneth M; Roden, Eric E; Xu, Huifang

2012-07-03

Sorption-desorption experiments show that the majority (ca. 80-90%) of U(VI) presorbed to mesoporous and nanoporous alumina could not be released by extended (2 week) extraction with 50 mM NaHCO(3) in contrast with non-nanoporous α alumina. The extent of reduction of U(VI) presorbed to aluminum oxides was semiquantitatively estimated by comparing the percentages of uranium desorbed by anoxic sodium bicarbonate between AH(2)DS-reacted and unreacted control samples. X-ray absorption spectroscopy confirmed that U(VI) presorbed to non-nanoporous alumina was rapidly and completely reduced to nanoparticulate uraninite by AH(2)DS, whereas reduction of U(VI) presorbed to nanoporous alumina was slow and incomplete (<5% reduction after 1 week). The observed nanopore size-dependent redox behavior of U has important implications in developing efficient remediation techniques for the subsurface uranium contamination because the efficiency of in situ bioremediation depends on how effectively and rapidly U(VI) bound to sediment or soil can be converted to an immobile phase.

Non-sticky translocation of bio-molecules through Tween 20-coated solid-state nanopores in a wide pH range

NASA Astrophysics Data System (ADS)

Li, Xiaoqing; Hu, Rui; Li, Ji; Tong, Xin; Diao, J. J.; Yu, Dapeng; Zhao, Qing

2016-10-01

Nanopore-based sensing technology is considered high-throughput and low-cost for single molecule detection, but solid-state nanopores have suffered from pore clogging issues. A simple Tween 20 coating method is applied to ensure long-term (several hours) non-sticky translocation of various types of bio-molecules through SiN nanopores in a wide pH range (4.0-13.0). We also emphasize the importance of choosing appropriate concentration of Tween 20 coating buffer for desired effect. By coating nanopores with a Tween 20 layer, we are able to differentiate between single-stranded DNA and double-stranded DNA, to identify drift-dominated domain for single-stranded DNA, to estimate BSA volume and to observe the shape of individual nucleosome translocation event without non-specific adsorption. The wide pH endurance from 4.0 to 13.0 and the broad types of detection analytes including nucleic acids, proteins, and biological complexes highlight the great application potential of Tween 20-coated solid-state nanopores.

Mean force potential of interaction between Na+ and Cl- ions in planar nanopores in contact with water under pressure

NASA Astrophysics Data System (ADS)

Shevkunov, S. V.

2017-11-01

The mean force potential (MFP) of interaction between counterions Na+ and Cl- in a planar nanopore with structureless hydrophobic walls is calculated via computer simulation under the condition that the nanopore is in contact with water at an external pressure that exceeds the saturation pressure but remains insufficient to fill the nanopore with water. For a nanopore with a liquid phase, the MFP dependence on the interionic distance indicates the dissociation of an ion pair into two hydrated ions in a nanopore that is not completely filled with water. Fluctuations in the number of water molecules drawn into the interionic space decisively influence the dissociation. The attraction between counterions, averaged over thermal fluctuations, depends largely on the pore width and grows as the shielding of the ions' electric field by water molecules in a narrow pore diminishes. The contributions from energy and entropy to the free energy of hydration are analyzed.

Fabrication of high reflectivity nanoporous distributed Bragg reflectors by controlled electrochemical etching of GaN

NASA Astrophysics Data System (ADS)

Lee, Seung-Min; Kang, Jin-Ho; Lee, June Key; Ryu, Sang-Wan

2016-09-01

The nanoporous medium is a valuable feature of optical devices because of its variable optical refractive index with porosity. One important application is in a GaN-based vertical cavity surface emitting laser having a distributed Bragg reflector (DBR) composed of alternating nanoporous and bulk GaNs. However, optimization of the fabrication process for high reflectivity DBRs having wellcontrolled high reflection bands has not been studied yet. We used electrochemical etching to study the fabrication process of a nanoporous GaN DBR and analyzed the relationship between the morphology and optical reflectivity. Several electrolytes were examined for the formation of the optimized nanoporous structure. A highly reflective DBRs having reflectivity of ~100% were obtained over a wide wavelength range of 450-750 nm. Porosification of semiconductors into nanoporous layers could provide a high reflectivity DBR due to controlled index-contrast, which would be advantages for the construction of a high-Q optical cavity.

Sensing small neurotransmitter-enzyme interaction with nanoporous gated ion-sensitive field effect transistors.

PubMed

Kisner, Alexandre; Stockmann, Regina; Jansen, Michael; Yegin, Ugur; Offenhäusser, Andreas; Kubota, Lauro Tatsuo; Mourzina, Yulia

2012-01-15

Ion-sensitive field effect transistors with gates having a high density of nanopores were fabricated and employed to sense the neurotransmitter dopamine with high selectivity and detectability at micromolar range. The nanoporous structure of the gates was produced by applying a relatively simple anodizing process, which yielded a porous alumina layer with pores exhibiting a mean diameter ranging from 20 to 35 nm. Gate-source voltages of the transistors demonstrated a pH-dependence that was linear over a wide range and could be understood as changes in surface charges during protonation and deprotonation. The large surface area provided by the pores allowed the physical immobilization of tyrosinase, which is an enzyme that oxidizes dopamine, on the gates of the transistors, and thus, changes the acid-base behavior on their surfaces. Concentration-dependent dopamine interacting with immobilized tyrosinase showed a linear dependence into a physiological range of interest for dopamine concentration in the changes of gate-source voltages. In comparison with previous approaches, a response time relatively fast for detecting dopamine was obtained. Additionally, selectivity assays for other neurotransmitters that are abundantly found in the brain were examined. These results demonstrate that the nanoporous structure of ion-sensitive field effect transistors can easily be used to immobilize specific enzyme that can readily and selectively detect small neurotransmitter molecule based on its acid-base interaction with the receptor. Therefore, it could serve as a technology platform for molecular studies of neurotransmitter-enzyme binding and drugs screening. Copyright © 2011 Elsevier B.V. All rights reserved.

Use of a nanoporous biodegradable miniature device to regulate cytokine release for cancer treatment

PubMed Central

He, Hongyan; Grignol, Valerie; Karpa, Volodymyr; Yen, Chi; LaPerle, Krista; Zhang, Xiaoli; Jones, Natalie B.; Liang, Margaret I.; Lesinski, Gregory B.; Ho, W.S. Winston; Carson, William E.; Lee, L. James

2014-01-01

The clinical management of locally recurrent or unresectable malignant melanoma continues to pose a significant challenge. These lesions are typically painful and currently available treatments, such as repeated intratumoral injections of interferon-alpha (IFN-α), are costly and inconvenient. Nanotechnology offers promise as a novel means of drug delivery. A capsule-like nanoporous miniature device (NMD) based on a biodegradable polymer, poly(polycaprolactone) (PCL) was developed for controlling the local delivery of immunological agents to the tumor microenvironment. The device consists of a nanoporous release gate, a fabricated drug reservoir loaded with IFN-α and a protective layer. To improve the biocompatibility of the device, a hydrophilic poly(ethylene glycol) monoacrylate was applied to the outside wall of the device via covalent bonding techniques. Microscopic visualization of the nanoporous gate from in vitro experiments exhibited good pore stability over a two-month period. In vitro experiments demonstrated a constant release rate of IFN-α from the NMD and showed that the release rate could be regulated by the gate area. The released IFN-α was biologically functional. Cytokine-containing supernatants from release experiments phosphorylated signal transducer and activator of transcription (STAT1) in peripheral blood mononuclear cells. Subcutaneous implantation of the NMDs was well tolerated and associated with an anti-tumor effect in a human xenograft model of melanoma. There was no evidence of a significant inflammatory response to the NMD or encapsulation of the NMD by fibrosis. These experiments show that the NMD can be fabricated and employed in vivo as a versatile drug delivery platform. PMID:21362447

Sugar and pH dual-responsive mesoporous silica nanocontainers based on competitive binding mechanisms

NASA Astrophysics Data System (ADS)

Yilmaz, M. Deniz; Xue, Min; Ambrogio, Michael W.; Buyukcakir, Onur; Wu, Yilei; Frasconi, Marco; Chen, Xinqi; Nassar, Majed S.; Stoddart, J. Fraser; Zink, Jeffrey I.

2014-12-01

A sugar and pH dual-responsive controlled release system, which is highly specific towards molecular stimuli, has been developed based on the binding between catechol and boronic acid on a platform of mesoporous silica nanoparticles (MSNs). By grafting phenylboronic acid stalks onto the silica surface, catechol-containing β-cyclodextrins can be attached to the orifices of the MSNs' nanopores through formation of boronate esters which block access to the nanopores. These esters are stable enough to prevent cargo molecules from escaping. The boronate esters disassociate in the presence of sugars, enabling the molecule-specific controlled-release feature of this hybrid system. The rate of release has been found to be tunable by varying both the structures and the concentrations of sugars, as a result of the competitive binding nature associated with the mechanism of its operation. Acidification also induces the release of cargo molecules. Further investigations show that the presence of both a low pH and sugar molecules provides cooperative effects which together control the rate of release.A sugar and pH dual-responsive controlled release system, which is highly specific towards molecular stimuli, has been developed based on the binding between catechol and boronic acid on a platform of mesoporous silica nanoparticles (MSNs). By grafting phenylboronic acid stalks onto the silica surface, catechol-containing β-cyclodextrins can be attached to the orifices of the MSNs' nanopores through formation of boronate esters which block access to the nanopores. These esters are stable enough to prevent cargo molecules from escaping. The boronate esters disassociate in the presence of sugars, enabling the molecule-specific controlled-release feature of this hybrid system. The rate of release has been found to be tunable by varying both the structures and the concentrations of sugars, as a result of the competitive binding nature associated with the mechanism of its operation. Acidification also induces the release of cargo molecules. Further investigations show that the presence of both a low pH and sugar molecules provides cooperative effects which together control the rate of release. Electronic supplementary information (ESI) available: Synthetic schemes, electron microscopy images and nitrogen adsorption/desorption isotherms of the nanoparticles, FT-IR spectra, isothermal titration calorimetry, X-ray photoelectron spectra and time-of-flight secondary ion mass spectra. DLS results for nanoparticle stability. See DOI: 10.1039/c4nr04796f

Formation, Characteristics and Electrocatalytic Properties of Nanoporous Metals Formed by Dealloying of Ternary-Noble Alloys

NASA Astrophysics Data System (ADS)

Vega Zuniga, Adrian A.

Nanoporous metals formed by electrochemical dealloying of silver from Ag-Au-Pt alloys, with 77 at.% silver and platinum contents of 1, 2 and 3 at.%, have been studied. The presence of platinum, which is immobile relative to gold, refine the ligament size and stabilized the nanostructure against coarsening, even under experimental conditions that would be expected to promote coarsening (e.g., exposure to high temperature, longer dealloying times). By adding only 1 at.% Pt to the alloy precursor, the ligament/pore size was reduced by 50% with respect to that in nanoporous gold (NPG), which was formed on a Ag-Au alloy with the same silver content as ternary alloys. A further decrease in the ligament size was observed by increasing the platinum content of the precursor; however, most of the improvement occurred with 1 at.% Pt. The adsorbate-induced surface segregation of platinum was also investigated for these nanoporous metals. By exposing freshly-dealloyed nanostructures to moderate temperatures in the presence of air, platinum segregated to the ligament surface; in contrast, in an inert atmosphere (Ar-H 2), platinum mostly reverted to the bulk of the ligaments. This thermally activated process was thermodynamically driven by the interaction between platinum and oxygen; however, at the desorption temperature of oxygen, platinum de-segregated from the surface. Moreover, the co-segregation of platinum and oxygen hindered the thermal coarsening of the ligaments. Finally, the electrocatalytic abilities of these nanostructures were studied towards methanol and ethanol electro-oxidation, in alkaline and acidic media, showing significantly improved response in comparison to that observed in NPG. The synergistic effect between gold and platinum atoms and the smaller feature size of the nanostructures were directly associated with this behaviour. In alkaline electrolyte, the nanostructure formed on the alloy with 1 at.% Pt showed higher catalytic response than the other two ternary nanostructures, which could be associated with the platinum/gold ratio on the surface of the structure. In acidic electrolyte, the nanostructure with the highest platinum content displayed the highest electrocatalytic response. Furthermore, the presence of platinum changed the selectivity of both reactions: the concentrations of carbonate produced increased by increasing the platinum content in the alloy precursor.

Fabrication and textural characterization of nanoporous carbon electrodes embedded with CuO nanoparticles for supercapacitors.

PubMed

Prasad, Kumaresa P S; Dhawale, Dattatray S; Sivakumar, Thiripuranthagan; Aldeyab, Salem S; Zaidi, Javaid S M; Ariga, Katsuhiko; Vinu, Ajayan

2011-08-01

We introduce a novel strategy of fabricating nanoporous carbons loaded with different amounts of CuO nanoparticles via a hard templating approach, using copper-containing mesoporous silica as the template and sucrose as the carbon source. The nature and dispersion of the CuO nanoparticles on the surface of the nanoporous carbons were investigated by x-ray diffraction (XRD), high-resolution scanning electron microscopy (HRSEM) and high-resolution transmission electron microscopy (HRTEM). XRD results reveal that nanoporous carbons with embedded CuO nanoparticles exhibit a well-ordered mesoporous structure, whereas the nitrogen adsorption measurements indicate the presence of excellent textural characteristics such as high surface area, large pore volume and uniform pore size distribution. The amount of CuO nanoparticles in the nanochannels of the nanoporous carbon could be controlled by simply varying the Si/Cu molar ratio of the mesoporous silica template. Morphological characterization by SEM and TEM reveals that high-quality CuO nanoparticles are distributed homogeneously within the nanoporous carbon framework. The supercapacitance behavior of the CuO-loaded nanoporous carbons was investigated. The material with a small amount of CuO in the mesochannels and high surface area affords a maximum specific capacitance of 300 F g -1 at a 20 mV s -1 scan rate in an aqueous electrolyte solution. A supercapacitor containing the CuO-loaded nanoporous carbon is highly stable and exhibits a long cycle life with 91% specific capacitance retained after 1000 cycles.

Fabrication and textural characterization of nanoporous carbon electrodes embedded with CuO nanoparticles for supercapacitors

NASA Astrophysics Data System (ADS)

Prasad, Kumaresa P. S.; Dhawale, Dattatray S.; Sivakumar, Thiripuranthagan; Aldeyab, Salem S.; Zaidi, Javaid S. M.; Ariga, Katsuhiko; Vinu, Ajayan

2011-08-01

We introduce a novel strategy of fabricating nanoporous carbons loaded with different amounts of CuO nanoparticles via a hard templating approach, using copper-containing mesoporous silica as the template and sucrose as the carbon source. The nature and dispersion of the CuO nanoparticles on the surface of the nanoporous carbons were investigated by x-ray diffraction (XRD), high-resolution scanning electron microscopy (HRSEM) and high-resolution transmission electron microscopy (HRTEM). XRD results reveal that nanoporous carbons with embedded CuO nanoparticles exhibit a well-ordered mesoporous structure, whereas the nitrogen adsorption measurements indicate the presence of excellent textural characteristics such as high surface area, large pore volume and uniform pore size distribution. The amount of CuO nanoparticles in the nanochannels of the nanoporous carbon could be controlled by simply varying the Si/Cu molar ratio of the mesoporous silica template. Morphological characterization by SEM and TEM reveals that high-quality CuO nanoparticles are distributed homogeneously within the nanoporous carbon framework. The supercapacitance behavior of the CuO-loaded nanoporous carbons was investigated. The material with a small amount of CuO in the mesochannels and high surface area affords a maximum specific capacitance of 300 F g-1 at a 20 mV s-1 scan rate in an aqueous electrolyte solution. A supercapacitor containing the CuO-loaded nanoporous carbon is highly stable and exhibits a long cycle life with 91% specific capacitance retained after 1000 cycles.

Identification of Essential Sensitive Regions of the Aerolysin Nanopore for Single Oligonucleotide Analysis.

PubMed

Wang, Ya-Qian; Li, Meng-Yin; Qiu, Hu; Cao, Chan; Wang, Ming-Bo; Wu, Xue-Yuan; Huang, Jin; Ying, Yi-Lun; Long, Yi-Tao

2018-06-11

The aerolysin nanopore channel is one of the confined spaces for single molecule analysis which displays high spatial and temporal resolution for the discrimination of single nucleotides, identification of DNA base modification, and analyzing the structural transition of DNAs. However, to overcome the challenge of achieving the ultimate goal of the widespread real analytical application, it is urgent to probe the sensing regions of the aerolysin to further improve the sensitivity. In this paper, we explore the sensing regions of the aerolysin nanopore by a series of well-designed mutant nanopore experiments combined with molecular dynamics simulations-based electrostatic analysis. The positively charged lumen-exposed Lys-238, identified as one of the key sensing sites due to the presence of a deep valley in the electrostatic potentials, was replaced by different charged and sized amino acids. The results show that the translocation time of oligonucleotides through the nanopore can be readily modulated by the choice of the target amino acid at the 238 site. In particular, a 7-fold slower translocation at a voltage bias of +120 mV is observed with respect to the wild-type aerolysin, which provides a high resolution for methylated cytosine discrimination. We further determine that both the electrostatic properties and geometrical structure of the aerolysin nanopore are crucial to its sensing ability. These insights open ways for rationally designing the sensing mechanism of the aerolysin nanopore, thus providing a novel paradigm for nanopore sensing.

Fabrication and textural characterization of nanoporous carbon electrodes embedded with CuO nanoparticles for supercapacitors

PubMed Central

Prasad, Kumaresa P S; Dhawale, Dattatray S; Sivakumar, Thiripuranthagan; Aldeyab, Salem S; Zaidi, Javaid S M; Ariga, Katsuhiko; Vinu, Ajayan

2011-01-01

We introduce a novel strategy of fabricating nanoporous carbons loaded with different amounts of CuO nanoparticles via a hard templating approach, using copper-containing mesoporous silica as the template and sucrose as the carbon source. The nature and dispersion of the CuO nanoparticles on the surface of the nanoporous carbons were investigated by x-ray diffraction (XRD), high-resolution scanning electron microscopy (HRSEM) and high-resolution transmission electron microscopy (HRTEM). XRD results reveal that nanoporous carbons with embedded CuO nanoparticles exhibit a well-ordered mesoporous structure, whereas the nitrogen adsorption measurements indicate the presence of excellent textural characteristics such as high surface area, large pore volume and uniform pore size distribution. The amount of CuO nanoparticles in the nanochannels of the nanoporous carbon could be controlled by simply varying the Si/Cu molar ratio of the mesoporous silica template. Morphological characterization by SEM and TEM reveals that high-quality CuO nanoparticles are distributed homogeneously within the nanoporous carbon framework. The supercapacitance behavior of the CuO-loaded nanoporous carbons was investigated. The material with a small amount of CuO in the mesochannels and high surface area affords a maximum specific capacitance of 300 F g-1 at a 20 mV s-1 scan rate in an aqueous electrolyte solution. A supercapacitor containing the CuO-loaded nanoporous carbon is highly stable and exhibits a long cycle life with 91% specific capacitance retained after 1000 cycles. PMID:27877410

Charging dynamics of supercapacitors with narrow cylindrical nanopores.

PubMed

Lee, Alpha A; Kondrat, Svyatoslav; Oshanin, Gleb; Kornyshev, Alexei A

2014-08-08

We present a coarse-grained, continuum kinetic theory for charging supercapacitors with narrow cylindrical nanopores. The theory reveals that the occupancy of a nonpolarized pore and the energy barrier for ion-ion interdiffusion are the key issues controlling the different regimes of dynamic response. For 'ionophobic' pores, where the pore is empty at no applied voltage, charge density advances into the pore via diffusion-like dynamics. The mechanism of charging an 'ionophilic' pore is starkly different: for moderate ionophilicities, co-ions are expelled from the pore in a front-like manner, with significant 'congestion' at the pore entrance predicted for strong ionophilicity. We thus show that pore ionophilicity is detrimental to the speed of charging/discharging cycles, whereas making pores more ionophobic can substantially accelerate charging and cyclic recharging.

Charging dynamics of supercapacitors with narrow cylindrical nanopores

NASA Astrophysics Data System (ADS)

Lee, Alpha A.; Kondrat, Svyatoslav; Oshanin, Gleb; Kornyshev, Alexei A.

2014-08-01

We present a coarse-grained, continuum kinetic theory for charging supercapacitors with narrow cylindrical nanopores. The theory reveals that the occupancy of a nonpolarized pore and the energy barrier for ion-ion interdiffusion are the key issues controlling the different regimes of dynamic response. For ‘ionophobic’ pores, where the pore is empty at no applied voltage, charge density advances into the pore via diffusion-like dynamics. The mechanism of charging an ‘ionophilic’ pore is starkly different: for moderate ionophilicities, co-ions are expelled from the pore in a front-like manner, with significant ‘congestion’ at the pore entrance predicted for strong ionophilicity. We thus show that pore ionophilicity is detrimental to the speed of charging/discharging cycles, whereas making pores more ionophobic can substantially accelerate charging and cyclic recharging.

Electro-elastoviscous response of polyaniline functionalized nano-porous zeolite based colloidal dispersions.

PubMed

Chattopadhyay, Ankur; Rani, Poonam; Srivastava, Rajendra; Dhar, Purbarun

2018-06-01

The present article discusses the typical influence of grafted conducting polymers in the mesoscale pores of dielectric particles on the static and dynamic electrorheology and electro-viscoelastic behavior of corresponding colloids. Nanocrystalline meso-nanoporous zeolite has been prepared by chemical synthesis and subsequently polyaniline (PANI) coating has been implemented. Electrorheological (ER) suspensions have been formed by dispersing the nanoparticles in silicone oil and their viscoelastic behaviors are examined to understand the nature of such complex colloidal systems under electric fields. PANI-Zeolite ER fluids demonstrate higher static electroviscous effects and yield stress potential than untreated Zeolite, typically studied in literature. Transient electro-viscous characterizations show a stable and negligible hysteresis behavior when both the fluids are exposed to constant as well as time varying electric field intensities. Further oscillatory shear experiments of frequency and strain sweeps exhibit predominant elastic behavior in case of Zeolite based ER suspensions as compared to PANI systems. Detailed investigations reveal Zeolite based ER suspensions display enhanced relative yielding as well as electro-viscoelastic stability than the PANI-Zeolite. The steady state viscous behaviors are scaled against the non-dimensional Mason number to model the system behavior for both fluids. Experimental data of flow behaviors of both the ER fluids are compared with semi-classical models and it is found that the CCJ model possesses a closer proximity than traditional Bingham model, thereby revealing the fluids to be generic pseudo-linear fluids. The present article reveals that while the PANI based fluids are typically hailed superior in literature, it is only restricted to steady shear utilities. In case of dynamic and oscillatory systems, the traditional Zeolite based fluids exhibit superior ER caliber. Copyright © 2018 Elsevier Inc. All rights reserved.

Analysis of electrolyte transport through charged nanopores.

PubMed

Peters, P B; van Roij, R; Bazant, M Z; Biesheuvel, P M

2016-05-01

We revisit the classical problem of flow of electrolyte solutions through charged capillary nanopores or nanotubes as described by the capillary pore model (also called "space charge" theory). This theory assumes very long and thin pores and uses a one-dimensional flux-force formalism which relates fluxes (electrical current, salt flux, and fluid velocity) and driving forces (difference in electric potential, salt concentration, and pressure). We analyze the general case with overlapping electric double layers in the pore and a nonzero axial salt concentration gradient. The 3×3 matrix relating these quantities exhibits Onsager symmetry and we report a significant new simplification for the diagonal element relating axial salt flux to the gradient in chemical potential. We prove that Onsager symmetry is preserved under changes of variables, which we illustrate by transformation to a different flux-force matrix given by Gross and Osterle [J. Chem. Phys. 49, 228 (1968)JCPSA60021-960610.1063/1.1669814]. The capillary pore model is well suited to describe the nonlinear response of charged membranes or nanofluidic devices for electrokinetic energy conversion and water desalination, as long as the transverse ion profiles remain in local quasiequilibrium. As an example, we evaluate electrical power production from a salt concentration difference by reverse electrodialysis, using an efficiency versus power diagram. We show that since the capillary pore model allows for axial gradients in salt concentration, partial loops in current, salt flux, or fluid flow can develop in the pore. Predictions for macroscopic transport properties using a reduced model, where the potential and concentration are assumed to be invariant with radial coordinate ("uniform potential" or "fine capillary pore" model), are close to results of the full model.

Biomimetic oral mucin from polymer micelle networks

NASA Astrophysics Data System (ADS)

Authimoolam, Sundar Prasanth

Mucin networks are formed by the complexation of bottlebrush-like mucin glycoprotein with other small molecule glycoproteins. These glycoproteins create nanoscale strands that then arrange into a nanoporous mesh. These networks play an important role in ensuring surface hydration, lubricity and barrier protection. In order to understand the functional behavior in mucin networks, it is important to decouple their chemical and physical effects responsible for generating the fundamental property-function relationship. To achieve this goal, we propose to develop a synthetic biomimetic mucin using a layer-by-layer (LBL) deposition approach. In this work, a hierarchical 3-dimensional structures resembling natural mucin networks was generated using affinity-based interactions on synthetic and biological surfaces. Unlike conventional polyelectrolyte-based LBL methods, pre-assembled biotin-functionalized filamentous (worm-like) micelles was utilized as the network building block, which from complementary additions of streptavidin generated synthetic networks of desired thickness. The biomimetic nature in those synthetic networks are studied by evaluating its structural and bio-functional properties. Structurally, synthetic networks formed a nanoporous mesh. The networks demonstrated excellent surface hydration property and were able capable of microbial capture. Those functional properties are akin to that of natural mucin networks. Further, the role of synthetic mucin as a drug delivery vehicle, capable of providing localized and tunable release was demonstrated. By incorporating antibacterial curcumin drug loading within synthetic networks, bacterial growth inhibition was also demonstrated. Thus, such bioactive interfaces can serve as a model for independently characterizing mucin network properties and through its role as a drug carrier vehicle it presents exciting future opportunities for localized drug delivery, in regenerative applications and as bio-functional implant coats. KEYWORDS: Biomimic, Bioapplication, Drug delivery, Filomicelle, Mucin, Polymer networks.

Method of making nanostructured glass-ceramic waste forms

DOEpatents

Gao, Huizhen; Wang, Yifeng; Rodriguez, Mark A.; Bencoe, Denise N.

2012-12-18

A method of rendering hazardous materials less dangerous comprising trapping the hazardous material in nanopores of a nanoporous composite material, reacting the trapped hazardous material to render it less volatile/soluble, sealing the trapped hazardous material, and vitrifying the nanoporous material containing the less volatile/soluble hazardous material.

DNA translocation measurements in solid-state nanopores fabricated using helium-ion microscope

NASA Astrophysics Data System (ADS)

Liu, Liping; Miao, Wang; Huynh, Chuong; Liu, Quanjun; Ling, Xinsheng

2012-02-01

We report high-quality DNA translocation measurements in solid-state nanopores drilled in free-standing SiN membranes by using a helium-ion beam in a Zeiss helium-ion microscope (HIM). We show that the HIM nanopores have similar performance as the TEM-drilled pores.