Nanomaterials

1704 KiB

Open AccessArticle

A Label-Free and Sensitive Fluorescent Qualitative Assay for Bisphenol A Based on Rolling Circle Amplification/Exonuclease III-Combined Cascade Amplification

by Xia Li, Juan Song, Qing-Wang Xue, Fu-Heng You, Xia Lu, Yan-Cong Kong, Shu-Yi Ma, Wei Jiang and Chen-Zhong Li

Nanomaterials 2016, 6(10), 190; https://doi.org/10.3390/nano6100190 - 21 Oct 2016

Cited by 16 | Viewed by 6207

Abstract

Bisphenol A (BPA) detection in drinking water and food packaging materials has attracted much attention since the discovery that BPA can interfere with normal physiological processes and cause adverse health effects. Here, we constructed a label-free aptamer fluorescent assay for selective and sensitive [...] Read more.

Bisphenol A (BPA) detection in drinking water and food packaging materials has attracted much attention since the discovery that BPA can interfere with normal physiological processes and cause adverse health effects. Here, we constructed a label-free aptamer fluorescent assay for selective and sensitive detection of BPA based on the rolling circle amplification (RCA)/Exonuclease III (Exo III)-combined cascade amplification strategy. First, the duplex DNA probe (RP) with anti-BPA aptamer and trigger sequence was designed for BPA recognition and signal amplification. Next, under the action of BPA, the trigger probe was liberated from RP to initiate RCA reaction as primary amplification. Subsequently, the RCA products were used to trigger Exo III assisted secondary amplification with the help of hairpin probes, producing plenty of “G-quadruplex” in lantern-like structures. Finally, the continuously enriched “G-quadruplex lanterns” were lightened by zinc(II)-protoporphyrin IX (ZnPPIX) generating enhanced fluorescence signals. By integrating the primary RCA and secondary Exo III mediated cascade amplification strategy, this method displayed an excellent sensitivity with the detection limits of 5.4 × 10⁻¹⁷ M. In addition, the anti-BPA aptamer exhibits high recognition ability with BPA, guaranteeing the specificity of detection. The reporter signal probe (G-quadruplex with ZnPPIX) provides a label-free fluorescence signals readout without complicated labeling procedures, making the method simple in design and cost-effective in operation. Moreover, environmental samples analysis was also performed, suggesting that our strategy was reliable and had a great potential application in environmental monitoring. Full article

(This article belongs to the Special Issue Nanostructured Biosensors 2016)

► Show Figures

Figure 1

2739 KiB

Open AccessArticle

Cytotoxicity of Silver Nanoparticle and Chitin-Nanofiber Sheet Composites Caused by Oxidative Stress

by Jun Kinoda, Masayuki Ishihara, Hidemi Hattori, Shingo Nakamura, Koichi Fukuda and Hidetaka Yokoe

Nanomaterials 2016, 6(10), 189; https://doi.org/10.3390/nano6100189 - 20 Oct 2016

Cited by 29 | Viewed by 5869

Abstract

Size-controlled spherical silver nanoparticles (<10 nm) and chitin-nanofiber sheet composites (Ag NPs/CNFS) have previously been reported to have strong antimicrobial activity in vitro. Although Ag NPs/CNFS have strong antimicrobial activity, their cytotoxicity has not been investigated. This study was performed to evaluate the [...] Read more.

Size-controlled spherical silver nanoparticles (<10 nm) and chitin-nanofiber sheet composites (Ag NPs/CNFS) have previously been reported to have strong antimicrobial activity in vitro. Although Ag NPs/CNFS have strong antimicrobial activity, their cytotoxicity has not been investigated. This study was performed to evaluate the effects of Ag NPs/CNFS on cytotoxicity for fibroblasts in vitro and healing delay of wound repair in vivo, focused on oxidative stress. Cytotoxic activities of Ag NPs/CNFS were investigated using a fibroblast cell proliferation assay, nitric oxide/nitrogen dioxide (NO/NO₂) measurement of the cell lysates in vitro, inhibitory effects of Ag NPs/CNFS on healing-impaired wound repair using diabetic mice in vivo, 8-hydroxy-2′-deoxyguanosine (8-OHdG) immunohistochemical staining of the skin sections, and generation of carbonyl protein in the wound was performed to evaluate cytotoxicity with oxidative stress. Ag NPs/CNFS exhibited cytotoxicity for fibroblasts and a significant increase of total NO/NO₂ levels in the cell lysates in vitro and increased levels of 8-OHdG and carbonyl proteins in vivo. Although wound repair in the continuously Ag NPs/CNFS-treated group was delayed, it could be mitigated by washing the covered wound with saline. Thus, Ag NPs/CNFS may become accepted as an anti-infectious wound dressing. Full article

(This article belongs to the Special Issue Antimicrobial Nanomaterials and Nanotechnology)

► Show Figures

Figure 1

2243 KiB

Open AccessArticle

Polymer Nanocomposite Film with Metal Rich Surface Prepared by In Situ Single-Step Formation of Palladium Nanoparticles: An Interesting Way to Combine Specific Functional Properties

by David Thompson, David Kranbuehl and Eliane Espuche

Nanomaterials 2016, 6(10), 188; https://doi.org/10.3390/nano6100188 - 18 Oct 2016

Cited by 4 | Viewed by 4208

Abstract

This paper presents a continuous single-step route that permits preparation of a thermostable polymer/metal nanocomposite film and to combine different functional properties in a unique material. More precisely, palladium nanoparticles are in situ generated in a polyimide matrix thanks to a designed curing [...] Read more.

This paper presents a continuous single-step route that permits preparation of a thermostable polymer/metal nanocomposite film and to combine different functional properties in a unique material. More precisely, palladium nanoparticles are in situ generated in a polyimide matrix thanks to a designed curing cycle which is applied to a polyamic acid/metal precursor solution cast on a glass plate. A metal-rich surface layer which is strongly bonded to the bulk film is formed in addition to homogeneously dispersed metal nanoparticles. This specific morphology leads to obtaining an optically reflective film. The metal nanoparticles act as gas diffusion barriers for helium, oxygen, and carbon dioxide; they induce a tortuosity effect which allows dividing the gas permeation coefficients by a factor near to 2 with respect to the neat polyimide matrix. Moreover, the ability of the in situ synthesized palladium nanoparticles to entrap hydrogen is evidenced. The nanocomposite film properties can be modulated as a function of the location of the film metal-rich surface with respect to the hydrogen feed. The synthesized nanocomposite could represent a major interest for a wide variety of applications, from specific coatings for aerospace or automotive industry, to catalysis applications or sensors. Full article

(This article belongs to the Special Issue Multifunctional Polymer-Based Nanocomposites)

► Show Figures

Figure 1

5639 KiB

Open AccessArticle

Oxidation of CO and Methanol on Pd-Ni Catalysts Supported on Different Chemically-Treated Carbon Nanofibers

by Juan Carlos Calderón, Miguel Rios Ráfales, María Jesús Nieto-Monge, Juan Ignacio Pardo, Rafael Moliner and María Jesús Lázaro

Nanomaterials 2016, 6(10), 187; https://doi.org/10.3390/nano6100187 - 18 Oct 2016

Cited by 14 | Viewed by 5325

Abstract

In this work, palladium-nickel nanoparticles supported on carbon nanofibers were synthesized, with metal contents close to 25 wt % and Pd:Ni atomic ratios near to 1:2. These catalysts were previously studied in order to determine their activity toward the oxygen reduction reaction. Before [...] Read more.

In this work, palladium-nickel nanoparticles supported on carbon nanofibers were synthesized, with metal contents close to 25 wt % and Pd:Ni atomic ratios near to 1:2. These catalysts were previously studied in order to determine their activity toward the oxygen reduction reaction. Before the deposition of metals, the carbon nanofibers were chemically treated in order to generate oxygen and nitrogen groups on their surface. Transmission electron microscopy analysis (TEM) images revealed particle diameters between 3 and 4 nm, overcoming the sizes observed for the nanoparticles supported on carbon black (catalyst Pd-Ni CB 1:2). From the CO oxidation at different temperatures, the activation energy E_act for this reaction was determined. These values indicated a high tolerance of the catalysts toward the CO poisoning, especially in the case of the catalysts supported on the non-chemically treated carbon nanofibers. On the other hand, apparent activation energy E_ap for the methanol oxidation was also determined finding—as a rate determining step—the CO_ads diffusion to the OH_ads for the catalysts supported on carbon nanofibers. The results here presented showed that the surface functional groups only play a role in the obtaining of lower particle sizes, which is an important factor in the obtaining of low CO oxidation activation energies. Full article

(This article belongs to the Special Issue Semiconductor Core/Shell Nanocrystals for Optoelectronic Applications)

► Show Figures

Figure 1

1785 KiB

Open AccessArticle

Effects of G-Quadruplex Topology on Electronic Transfer Integrals

by Wenming Sun, Daniele Varsano and Rosa Di Felice

Nanomaterials 2016, 6(10), 184; https://doi.org/10.3390/nano6100184 - 15 Oct 2016

Cited by 10 | Viewed by 4539

Abstract

G-quadruplex is a quadruple helical form of nucleic acids that can appear in guanine-rich parts of the genome. The basic unit is the G-tetrad, a planar assembly of four guanines connected by eight hydrogen bonds. Its rich topology and its possible relevance as [...] Read more.

G-quadruplex is a quadruple helical form of nucleic acids that can appear in guanine-rich parts of the genome. The basic unit is the G-tetrad, a planar assembly of four guanines connected by eight hydrogen bonds. Its rich topology and its possible relevance as a drug target for a number of diseases have stimulated several structural studies. The superior stiffness and electronic π-π overlap between consecutive G-tetrads suggest exploitation for nanotechnologies. Here we inspect the intimate link between the structure and the electronic properties, with focus on charge transfer parameters. We show that the electronic couplings between stacked G-tetrads strongly depend on the three-dimensional atomic structure. Furthermore, we reveal a remarkable correlation with the topology: a topology characterized by the absence of syn-anti G-G sequences can better support electronic charge transfer. On the other hand, there is no obvious correlation of the electronic coupling with usual descriptors of the helix shape. We establish a procedure to maximize the correlation with a global helix shape descriptor. Full article

(This article belongs to the Special Issue DNA-Based Nanotechnology)

► Show Figures

Graphical abstract

3359 KiB

Open AccessArticle

Triboelectric Hydrogen Gas Sensor with Pd Functionalized Surface

by Sung-Ho Shin, Yang Hyeog Kwon, Young-Hwan Kim, Joo-Yun Jung and Junghyo Nah

Nanomaterials 2016, 6(10), 186; https://doi.org/10.3390/nano6100186 - 14 Oct 2016

Cited by 29 | Viewed by 6943

Abstract

Palladium (Pd)-based hydrogen (H₂) gas sensors have been widely investigated thanks to its fast reaction and high sensitivity to hydrogen. Various sensing mechanisms have been adopted for H₂ gas sensors; however, all the sensors must be powered through an external [...] Read more.

Palladium (Pd)-based hydrogen (H₂) gas sensors have been widely investigated thanks to its fast reaction and high sensitivity to hydrogen. Various sensing mechanisms have been adopted for H₂ gas sensors; however, all the sensors must be powered through an external battery. We report here an H₂ gas sensor that can detect H₂ by measuring the output voltages generated during contact electrification between two friction surfaces. When the H₂ sensor, composed of Pd-coated ITO (indium tin oxide) and PET (polyethylene Terephthalate) film, is exposed to H₂, its output voltage is varied in proportion to H₂ concentration because the work function (WF) of Pd-coated surface changes, altering triboelectric charging behavior. Specifically, the output voltage of the sensor is gradually increased as exposing H₂ concentration increases. Reproducible and sensitive sensor response was observed up 1% H₂ exposure. The approach introduced here can easily be adopted to development of triboelectric gas sensors detecting other gas species. Full article

(This article belongs to the Special Issue Nanostructured Biosensors 2016)

► Show Figures

Figure 1

647 KiB

Open AccessCorrection

Correction: Yan, X., et al. Study on Utilization of Carboxyl Group Decorated Carbon Nanotubes and Carbonation Reaction for Improving Strengths and Microstructures of Cement Paste. Nanomaterials 2016, 6, 153

by Xiantong Yan, Hongzhi Cui, Qinghua Qin, Waiching Tang and Xiangming Zhou

Nanomaterials 2016, 6(10), 185; https://doi.org/10.3390/nano6100185 - 13 Oct 2016

Cited by 2 | Viewed by 3454

Abstract

The authors wish to make the following correction to this paper [1].[...] Full article

(This article belongs to the Special Issue Nanomechanics of Carbon Nanotubes and Graphene Sheets)

► Show Figures

Figure 3

2156 KiB

Open AccessArticle

A Study of Inverted-Type Perovskite Solar Cells with Various Composition Ratios of (FAPbI₃)_1−x(MAPbBr₃)_x

by Lung-Chien Chen, Zong-Liang Tseng and Jun-Kai Huang

Nanomaterials 2016, 6(10), 183; https://doi.org/10.3390/nano6100183 - 13 Oct 2016

Cited by 24 | Viewed by 8859

Abstract

This work presents mixed (FAPbI₃)_1−x(MAPbBr₃)_x perovskite films with various composition ratios, x (x = 0–1), which are formed using the spin coating method. The structural, optical, and electronic behaviors of the mixed (FAPbI₃ [...] Read more.

This work presents mixed (FAPbI₃)_1−x(MAPbBr₃)_x perovskite films with various composition ratios, x (x = 0–1), which are formed using the spin coating method. The structural, optical, and electronic behaviors of the mixed (FAPbI₃)_1−x(MAPbBr₃)_x perovskite films are discussed. A device with structure glass/indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)/mixed perovskite/C₆₀/BCP/Ag was fabricated. The mixed perovskite film was an active light-harvesting layer. PEDOT:PSS was a hole transporting layer between the ITO and perovskite. Both C₆₀ and bathocuproine (BCP) were electron transporting layers. MAPbBr₃ was added to FAPbI₃ with a composition ratio of x = 0.2, stabilizing the perovskite phase, which exhibited a uniform and dense morphology. The optimal device exhibited band matching with C₆₀, resulting in a low series resistance (R_sh) and a high fill factor (FF). Therefore, the device with composition (FAPbI₃)_1−x(MAPbBr₃)_x and x = 0.2 exhibited outstanding performance. Full article

(This article belongs to the Special Issue Colloidal Quantum Dots (QDs) for Display, Solar Cells and Bio-Image Applications)

► Show Figures

Figure 1

2896 KiB

Open AccessArticle

Effect of Continuous Multi-Walled Carbon Nanotubes on Thermal and Mechanical Properties of Flexible Composite Film

by Ji Eun Cha, Seong Yun Kim and Seung Hee Lee

Nanomaterials 2016, 6(10), 182; https://doi.org/10.3390/nano6100182 - 12 Oct 2016

Cited by 29 | Viewed by 6940

Abstract

To investigate the effect of continuous multi-walled carbon nanotubes (MWCNTs) on the thermal and mechanical properties of composites, we propose a fabrication method for a buckypaper-filled flexible composite film prepared by a two-step process involving buckypaper fabrication using vacuum filtration of MWCNTs, and [...] Read more.

To investigate the effect of continuous multi-walled carbon nanotubes (MWCNTs) on the thermal and mechanical properties of composites, we propose a fabrication method for a buckypaper-filled flexible composite film prepared by a two-step process involving buckypaper fabrication using vacuum filtration of MWCNTs, and composite film fabrication using the dipping method. The thermal conductivity and tensile strength of the composite film filled with the buckypaper exhibited improved results, respectively 76% and 275% greater than those of the individual MWCNT-filled composite film. It was confirmed that forming continuous MWCNT fillers is an important factor which determines the physical characteristics of the composite film. In light of the study findings, composite films using buckypaper as a filler and polydimethylsiloxane (PDMS) as a flexible matrix have sufficient potential to be applied as a heat-dissipating material, and as a flexible film with high thermal conductivity and excellent mechanical properties. Full article

(This article belongs to the Special Issue Textiles Nanotechnology)

► Show Figures

Graphical abstract

3859 KiB

Open AccessArticle

Separation of Bacteria, Protozoa and Carbon Nanotubes by Density Gradient Centrifugation

by Monika Mortimer, Elijah J. Petersen, Bruce A. Buchholz and Patricia A. Holden

Nanomaterials 2016, 6(10), 181; https://doi.org/10.3390/nano6100181 - 12 Oct 2016

Cited by 21 | Viewed by 9687

Abstract

Sustainable production and use of carbon nanotube (CNT)-enabled materials require efficient assessment of CNT environmental hazards, including the potential for CNT bioaccumulation and biomagnification in environmental receptors. Microbes, as abundant organisms responsible for nutrient cycling in soil and water, are important ecological receptors [...] Read more.

Sustainable production and use of carbon nanotube (CNT)-enabled materials require efficient assessment of CNT environmental hazards, including the potential for CNT bioaccumulation and biomagnification in environmental receptors. Microbes, as abundant organisms responsible for nutrient cycling in soil and water, are important ecological receptors for studying the effects of CNTs. Quantification of CNT association with microbial cells requires efficient separation of CNT-associated cells from individually dispersed CNTs and CNT agglomerates. Here, we designed, optimized, and demonstrated procedures for separating bacteria (Pseudomonas aeruginosa) from unbound multiwall carbon nanotubes (MWCNTs) and MWCNT agglomerates using sucrose density gradient centrifugation. We demonstrate separation of protozoa (Tetrahymena thermophila) from MWCNTs, bacterial agglomerates, and protozoan fecal pellets by centrifugation in an iodixanol solution. The presence of MWCNTs in the density gradients after centrifugation was determined by quantification of ¹⁴C-labeled MWCNTs; the recovery of microbes from the density gradient media was confirmed by optical microscopy. Protozoan intracellular contents of MWCNTs and of bacteria were also unaffected by the designed separation process. The optimized methods contribute to improved efficiency and accuracy in quantifying MWCNT association with bacteria and MWCNT accumulation in protozoan cells, thus supporting improved assessment of CNT bioaccumulation. Full article

(This article belongs to the Special Issue Engineered Nanomaterials in the Environment)

► Show Figures

Figure 1

2413 KiB

Open AccessReview

Probe Microscopic Studies of DNA Molecules on Carbon Nanotubes

by Kazuo Umemura, Katsuki Izumi and Shusuke Oura

Nanomaterials 2016, 6(10), 180; https://doi.org/10.3390/nano6100180 - 08 Oct 2016

Cited by 13 | Viewed by 6118

Abstract

Hybrids of DNA and carbon nanotubes (CNTs) are promising nanobioconjugates for nanobiosensors, carriers for drug delivery, and other biological applications. In this review, nanoscopic characterization of DNA-CNT hybrids, in particular, characterization by scanning probe microscopy (SPM), is summarized. In many studies, topographical imaging [...] Read more.

Hybrids of DNA and carbon nanotubes (CNTs) are promising nanobioconjugates for nanobiosensors, carriers for drug delivery, and other biological applications. In this review, nanoscopic characterization of DNA-CNT hybrids, in particular, characterization by scanning probe microscopy (SPM), is summarized. In many studies, topographical imaging by atomic force microscopy has been performed. However, some researchers have demonstrated advanced SPM operations in order to maximize its unique and valuable functions. Such sophisticated approaches are attractive and will have a significant impact on future studies of DNA-CNT hybrids. Full article

(This article belongs to the Special Issue DNA-Based Nanotechnology)

► Show Figures

Figure 1

3838 KiB

Open AccessArticle

Zinc Oxide Nanorods-Decorated Graphene Nanoplatelets: A Promising Antimicrobial Agent against the Cariogenic Bacterium Streptococcus mutans

by Elena Zanni, Chandrakanth Reddy Chandraiahgari, Giovanni De Bellis, Maria Rita Montereali, Giovanna Armiento, Paolo Ballirano, Antonella Polimeni, Maria Sabrina Sarto and Daniela Uccelletti

Nanomaterials 2016, 6(10), 179; https://doi.org/10.3390/nano6100179 - 29 Sep 2016

Cited by 59 | Viewed by 7937

Abstract

Nanomaterials are revolutionizing the field of medicine to improve the quality of life due to the myriad of applications stemming from their unique properties, including the antimicrobial activity against pathogens. In this study, the antimicrobial and antibiofilm properties of a novel nanomaterial composed [...] Read more.

Nanomaterials are revolutionizing the field of medicine to improve the quality of life due to the myriad of applications stemming from their unique properties, including the antimicrobial activity against pathogens. In this study, the antimicrobial and antibiofilm properties of a novel nanomaterial composed by zinc oxide nanorods-decorated graphene nanoplatelets (ZNGs) are investigated. ZNGs were produced by hydrothermal method and characterized through field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) techniques. The antimicrobial activity of ZNGs was evaluated against Streptococcus mutans, the main bacteriological agent in the etiology of dental caries. Cell viability assay demonstrated that ZNGs exerted a strikingly high killing effect on S. mutans cells in a dose-dependent manner. Moreover, FE-SEM analysis revealed relevant mechanical damages exerted by ZNGs at the cell surface of this dental pathogen rather than reactive oxygen species (ROS) generation. In addition, inductively coupled plasma mass spectrometry (ICP-MS) measurements showed negligible zinc dissolution, demonstrating that zinc ion release in the suspension is not associated with the high cell mortality rate. Finally, our data indicated that also S. mutans biofilm formation was affected by the presence of graphene-zinc oxide (ZnO) based material, as witnessed by the safranin staining and growth curve analysis. Therefore, ZNGs can be a remarkable nanobactericide against one of the main dental pathogens. The potential applications in dental care and therapy are very promising. Full article

(This article belongs to the Special Issue Antimicrobial Nanomaterials and Nanotechnology)

► Show Figures

Figure 1

8919 KiB

Open AccessArticle

Simultaneous Detection of Dopamine and Uric Acid Using a Poly(l-lysine)/Graphene Oxide Modified Electrode

by Yuehua Zhang, Wu Lei, Yujuan Xu, Xifeng Xia and Qingli Hao

Nanomaterials 2016, 6(10), 178; https://doi.org/10.3390/nano6100178 - 28 Sep 2016

Cited by 53 | Viewed by 9053

Abstract

A novel, simple and selective electrochemical method was investigated for the simultaneous detection of dopamine (DA) and uric acid (UA) on a poly(l-lysine)/graphene oxide (GO) modified glassy carbon electrode (PLL/GO/GCE) by differential pulse voltammetry (DPV). The electrochemically prepared PLL/GO sensory platform [...] Read more.

A novel, simple and selective electrochemical method was investigated for the simultaneous detection of dopamine (DA) and uric acid (UA) on a poly(l-lysine)/graphene oxide (GO) modified glassy carbon electrode (PLL/GO/GCE) by differential pulse voltammetry (DPV). The electrochemically prepared PLL/GO sensory platform toward the oxidation of UA and DA exhibited several advantages, including high effective surface area, more active sites and enhanced electrochemical activity. Compared to the PLL-modified GCE (PLL/GCE), GO-modified GCE and bare GCE, the PLL/GO/GCE exhibited an increase in the anodic potential difference and a remarkable enhancement in the current responses for both UA and DA. For the simultaneous detection of DA and UA, the detection limits of 0.021 and 0.074 μM were obtained, while 0.031 and 0.018 μM were obtained as the detection limits for the selective detection of UA and DA, using DPV in the linear concentration ranges of 0.5 to 20.0 and 0.5 to 35 μM, respectively. In addition, the PLL/GO/GCE demonstrated good reproducibility, long-term stability, excellent selectivity and negligible interference of ascorbic acid (AA). The proposed modified electrode was successfully implemented in the simultaneous detection of DA and UA in human blood serum, urine and dopamine hydrochloride injection with satisfactory results. Full article

(This article belongs to the Special Issue Nanomaterials for Electrocatalysis)

► Show Figures

Graphical abstract

1732 KiB

Open AccessArticle

Ionic Adsorption and Desorption of CNT Nanoropes

by Jun-Jun Shang, Qing-Sheng Yang, Xiao-Hui Yan, Xiao-Qiao He and Kim-Meow Liew

Nanomaterials 2016, 6(10), 177; https://doi.org/10.3390/nano6100177 - 28 Sep 2016

Cited by 8 | Viewed by 4741

Abstract

A nanorope is comprised of several carbon nanotubes (CNTs) with different chiralities. A molecular dynamic model is built to investigate the ionic adsorption and desorption of the CNT nanoropes. The charge distribution on the nanorope is obtained by using a modified gradient method [...] Read more.

A nanorope is comprised of several carbon nanotubes (CNTs) with different chiralities. A molecular dynamic model is built to investigate the ionic adsorption and desorption of the CNT nanoropes. The charge distribution on the nanorope is obtained by using a modified gradient method based on classical electrostatic theory. The electrostatic interactions among charged carbon atoms are calculated by using the Coulomb law. It was found here that the charged nanorope can adsorb heavy metal ions, and the adsorption and desorption can be realized by controlling the strength of applied electric field. The distance between the ions and the nanorope as well as the amount of ions have an effect on the adsorption capacity of the nanorope. The desorption process takes less time than that of adsorption. The study indicates that the CNT nanorope can be used as a core element of devices for sewage treatment. Full article

(This article belongs to the Special Issue Nanomechanics of Carbon Nanotubes and Graphene Sheets)

► Show Figures

Graphical abstract

1769 KiB

Open AccessArticle

Silver Nanoparticle-Embedded Thin Silica-Coated Graphene Oxide as an SERS Substrate

by Xuan-Hung Pham, Eunil Hahm, Hyung-Mo Kim, Seongbo Shim, Tae Han Kim, Dae Hong Jeong, Yoon-Sik Lee and Bong-Hyun Jun

Nanomaterials 2016, 6(10), 176; https://doi.org/10.3390/nano6100176 - 22 Sep 2016

Cited by 14 | Viewed by 8423

Abstract

A hybrid of Ag nanoparticle (NP)-embedded thin silica-coated graphene oxide (GO@SiO₂@Ag NPs) was prepared as a surface-enhanced Raman scattering (SERS) substrate. A 6 nm layer of silica was successfully coated on the surface of GO by the physical adsorption of sodium [...] Read more.

A hybrid of Ag nanoparticle (NP)-embedded thin silica-coated graphene oxide (GO@SiO₂@Ag NPs) was prepared as a surface-enhanced Raman scattering (SERS) substrate. A 6 nm layer of silica was successfully coated on the surface of GO by the physical adsorption of sodium silicate, followed by the hydrolysis of 3-mercaptopropyl trimethoxysilane. Ag NPs were introduced onto the thin silica-coated graphene oxide by the reduction of Ag⁺ to prepare GO@SiO₂@Ag NPs. The GO@SiO₂@Ag NPs exhibited a 1.8-fold enhanced Raman signal compared to GO without a silica coating. The GO@SiO₂@Ag NPs showed a detection limit of 4-mercaptobenzoic acid (4-MBA) at 0.74 μM. Full article

(This article belongs to the Special Issue 2D Nanomaterials: Graphene and Beyond Graphene)

► Show Figures

Graphical abstract

Journal Menu

Journal Browser

Nanomaterials, Volume 6, Issue 10 (October 2016) – 15 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI