Nanomaterials

26 pages, 5767 KiB

Open AccessArticle

Magnetic Nanoclusters Coated with Albumin, Casein, and Gelatin: Size Tuning, Relaxivity, Stability, Protein Corona, and Application in Nuclear Magnetic Resonance Immunoassay

by Pavel Khramtsov, Irina Barkina, Maria Kropaneva, Maria Bochkova, Valeria Timganova, Anton Nechaev, Il’ya Byzov, Svetlana Zamorina, Anatoly Yermakov and Mikhail Rayev

Nanomaterials 2019, 9(9), 1345; https://doi.org/10.3390/nano9091345 - 19 Sep 2019

Cited by 21 | Viewed by 5525

Abstract

The surface functionalization of magnetic nanoparticles improves their physicochemical properties and applicability in biomedicine. Natural polymers, including proteins, are prospective coatings capable of increasing the stability, biocompatibility, and transverse relaxivity (r2) of magnetic nanoparticles. In this work, we functionalized the nanoclusters of carbon-coated [...] Read more.

The surface functionalization of magnetic nanoparticles improves their physicochemical properties and applicability in biomedicine. Natural polymers, including proteins, are prospective coatings capable of increasing the stability, biocompatibility, and transverse relaxivity (r2) of magnetic nanoparticles. In this work, we functionalized the nanoclusters of carbon-coated iron nanoparticles with four proteins: bovine serum albumin, casein, and gelatins A and B, and we conducted a comprehensive comparative study of their properties essential to applications in biosensing. First, we examined the influence of environmental parameters on the size of prepared nanoclusters and synthesized protein-coated nanoclusters with a tunable size. Second, we showed that protein coating does not significantly influence the r2 relaxivity of clustered nanoparticles; however, the uniform distribution of individual nanoparticles inside the protein coating facilitates increased relaxivity. Third, we demonstrated the applicability of the obtained nanoclusters in biosensing by the development of a nuclear-magnetic-resonance-based immunoassay for the quantification of antibodies against tetanus toxoid. Fourth, the protein coronas of nanoclusters were studied using SDS-PAGE and Bradford protein assay. Finally, we compared the colloidal stability at various pH values and ionic strengths and in relevant complex media (i.e., blood serum, plasma, milk, juice, beer, and red wine), as well as the heat stability, resistance to proteolytic digestion, and shelf-life of protein-coated nanoclusters. Full article

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11 pages, 7960 KiB

Open AccessArticle

Efficient Production of Multi-Layer Graphene from Graphite Flakes in Water by Lipase-Graphene Sheets Conjugation

by Noelia Losada-Garcia, Angel Berenguer-Murcia, Diego Cazorla-Amorós and Jose M. Palomo

Nanomaterials 2019, 9(9), 1344; https://doi.org/10.3390/nano9091344 - 19 Sep 2019

Cited by 5 | Viewed by 3971

Abstract

Biographene was successfully produced in water from graphite flakes by a simple, rapid, and efficient methodology based on a bioexfoliation technology. The methodology consisted in the application of a lipase, with a unique mechanism of interaction with hydrophobic surfaces, combined with a previous [...] Read more.

Biographene was successfully produced in water from graphite flakes by a simple, rapid, and efficient methodology based on a bioexfoliation technology. The methodology consisted in the application of a lipase, with a unique mechanism of interaction with hydrophobic surfaces, combined with a previous mechanical sonication, to selectively generate lipase-graphene sheets conjugates in water at room temperature. The adsorption of the lipase on the graphene sheets permits to keep the sheets separated in comparison with other methods. It was possible to obtain more than 80% of graphene (in the form of multi-layer graphene) from low-cost graphite and with less damage compared to commercial graphene oxide (GO) or reduced GO. Experimental analysis demonstrated the formation of multi-layer graphene (MLG) mainly using lipase from Thermomyces Lanuginosus (TLL). Full article

(This article belongs to the Special Issue Characterization, Synthesis and Applications of 2D Nanomaterials)

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14 pages, 2533 KiB

Open AccessArticle

Amphiphilic Oxygenated Amorphous Carbon-Graphite Buckypapers with Gas Sensitivity to Polar and Non-Polar VOCs

by Shahin Homaeigohar

Nanomaterials 2019, 9(9), 1343; https://doi.org/10.3390/nano9091343 - 19 Sep 2019

Cited by 9 | Viewed by 3401

Abstract

To precisely control the emission limit of volatile organic compounds (VOCs) even at trace amounts, reactive nanomaterials of, e.g., carbon are demanded. Particularly, considering the polar/non-polar nature of VOCs, amphiphilic carbon nanomaterials with a huge surface area could act as multipurpose VOC sensors. [...] Read more.

To precisely control the emission limit of volatile organic compounds (VOCs) even at trace amounts, reactive nanomaterials of, e.g., carbon are demanded. Particularly, considering the polar/non-polar nature of VOCs, amphiphilic carbon nanomaterials with a huge surface area could act as multipurpose VOC sensors. Here, for the first time, a buckypaper sensor composed of oxygenated amorphous carbon (a-CO_x)/graphite (G) nanofilaments is developed. Presence of the oxygen-containing groups rises the selectivity of the sensor to polar VOCs, such as ethanol and acetone through formation of hydrogen bonding, affecting the electron withdrawing ability of the group, the hole carrier density, and, thus, the resistivity. On the other hand, the electrostatic interactions between the toluene aromatic ring and the π electrons of the graphitic crystals cause a formation of charge-transfer complexes, which could be the main mechanism of high responsiveness of the sensor towards non-polar toluene. To the best of my knowledge, an amphiphilic carbon nanofilamentous buckypaper has never been reported for gas sensing, and my device sensing polar/non-polar VOCs is state of the art for environmental control. Full article

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Electrically conductive oxygenated amorphous carbon (a-COx)/graphite (G) (a-COx/G) nanofibers able to sense polar (here, ethanol and acetone) and non-polar (here, toluene) volatile organic compounds (VOCs). Full article ">Figure 2
(a) The step-wise production process of a-COx/G nanofibers; (b) the schematic illustration of the gas sensing set-up comprising a glass substrate overlaid by gold contact electrodes, where the nanofilaments sit and are exposed to the gas analytes; (c) morphology and dimensions of the a-COx/G nanofibers (the nanofibers’ diameter shrinks within the course of the graphitization process); (d) the camera image shows the flexibility of the buckypaper; (e) morphology and dimensions of the chopped a-COx/G nanofilaments (the inset pictures are the atomic force microscopy (AFM) micrographs showing morphology and dimension of individual nanofilaments (upper left) and the SEM micrograph showing morphology of the nanofilaments at a high magnification (lower left)); (f) TEM image indicates the presence of two distinct regions distinguished by their different color intensity. The darker regions imply the aligned, graphitic, and dense arrangement of carbon elements, while the brighter regions are related to sparse and haphazard amorphous carbon. Full article ">Figure 3
Structural properties of the a-COx/G nanofilaments. (a) XRD verifying formation of graphite crystallites, along with a-COx domains; (b) ATR-FTIR showing the surface chemistry of a-COx/G nanofilaments; (c) Brunauer–Emmett–Teller (BET) surface area measured for the carbon nanofilament-based membrane (chopped carbon nanofilament membrane (CCNFM)) versus the carbon nanofiber-based membrane (carbon nanofiber membrane (CNFM)), stressing the effect of the chopping process on the enhancement of the surface area; (d) N2 adsorption isotherm for the CNFM and CCNFM, implying larger adsorption of nitrogen molecules onto the CCNFM versus the CNFM, due to its more extensive surface area. (e) Influence of the carbonization temperature on electrical conductivity of carbon nanofibers (CNFs); (f) electrical conductivity of the CCNFM versus that of the CNFM. The large difference between the conductivity of the CNFM and CCNFM implies that the chopping process declines the conductivity by lowering the continuity and cross links of the fibers, as witnessed by the inset SEM images (scale bars represent 20 µm). Full article ">Figure 4
(a) Volatile organic compound (VOC) gas response of the a-COx/G buckypapers; (b–d) the recovery property of the a-COx/G buckypapers exposed to ethanol, acetone, and toluene, respectively. Full article ">Figure 5
(a) ATR-FTIR showing the surface chemistry of a-COx/G nanofilaments as non-functionalized (black line) versus citric acid (CA)-functionalized (blue line) (I, II, and III represent C-O-C, C=O, and OH groups, respectively); (b) electrical conductivity of the carbon nanofilament-based membrane (buckypaper) as non-functionalized versus CA-functionalized; (c) toluene gas response of the a-COx/G buckypapers as CA-functionalized and non-functionalized. Full article ">

7 pages, 2216 KiB

Open AccessLetter

Palladium (III) Fluoride Bulk and PdF₃/Ga₂O₃/PdF₃ Magnetic Tunnel Junction: Multiple Spin-Gapless Semiconducting, Perfect Spin Filtering, and High Tunnel Magnetoresistance

by Zongbin Chen, Tingzhou Li, Tie Yang, Heju Xu, Rabah Khenata, Yongchun Gao and Xiaotian Wang

Nanomaterials 2019, 9(9), 1342; https://doi.org/10.3390/nano9091342 - 19 Sep 2019

Cited by 7 | Viewed by 3009

Abstract

Spin-gapless semiconductors (SGSs) with Dirac-like band crossings may exhibit massless fermions and dissipationless transport properties. In this study, by applying the density functional theory, novel multiple linear-type spin-gapless semiconducting band structures were found in a synthesized

R \bar{3} c

-type bulk PdF [...] Read more.

Spin-gapless semiconductors (SGSs) with Dirac-like band crossings may exhibit massless fermions and dissipationless transport properties. In this study, by applying the density functional theory, novel multiple linear-type spin-gapless semiconducting band structures were found in a synthesized

R \bar{3} c

-type bulk PdF₃ compound, which has potential applications in ultra-fast and ultra-low power spintronic devices. The effects of spin-orbit coupling and on-site Coulomb interaction were determined for the bulk material in this study. To explore the potential applications in spintronic devices, we also performed first-principles combined with the non-equilibrium Green’s function for the PdF₃/Ga₂O₃/PdF₃ magnetic tunnel junction (MTJ). The results suggested that this MTJ exhibits perfect spin filtering and high tunnel magnetoresistance (~5.04 × 10⁷). Full article

(This article belongs to the Special Issue Nanoelectronics: Concepts, Theory and Modeling)

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18 pages, 16115 KiB

Open AccessArticle

Preparation, Characterization, and Performance Analysis of S-Doped Bi₂MoO₆ Nanosheets

by Ruiqi Wang, Duanyang Li, Hailong Wang, Chenglun Liu and Longjun Xu

Nanomaterials 2019, 9(9), 1341; https://doi.org/10.3390/nano9091341 - 19 Sep 2019

Cited by 34 | Viewed by 4932

Abstract

S-doped Bi₂MoO₆ nanosheets were successfully synthesized by a simple hydrothermal method. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), N₂ adsorption–desorption isotherms, Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), elemental [...] Read more.

S-doped Bi₂MoO₆ nanosheets were successfully synthesized by a simple hydrothermal method. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), N₂ adsorption–desorption isotherms, Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), elemental mapping spectroscopy, photoluminescence spectra (PL), X-ray photoelectron spectroscopy (XPS), and UV-visible diffused reflectance spectra (UV-vis DRS). The photo-electrochemical performance of the samples was investigated via an electrochemical workstation. The S-doped Bi₂MoO₆ nanosheets exhibited enhanced photocatalytic activity under visible light irradiation. The photo-degradation rate of Rhodamine B (RhB) by S-doped Bi₂MoO₆ (1 wt%) reached 97% after 60 min, which was higher than that of the pure Bi₂MoO₆ and other S-doped products. The degradation rate of the recovered S-doped Bi₂MoO₆ (1 wt%) was still nearly 90% in the third cycle, indicating an excellent stability of the catalyst. The radical-capture experiments confirmed that superoxide radicals (·O²⁻) and holes (h⁺) were the main active substances in the photocatalytic degradation of RhB by S-doped Bi₂MoO₆. Full article

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13 pages, 29267 KiB

Open AccessArticle

Biotransformation of Pristine and Oxidized Carbon Nanotubes by the White Rot Fungus Phanerochaete chrysosporium

by Qiang Ma, Ailimire Yilihamu, Zhu Ming, Shengnan Yang, Mengyao Shi, Bowei Ouyang, Qiangqiang Zhang, Xin Guan and Sheng-Tao Yang

Nanomaterials 2019, 9(9), 1340; https://doi.org/10.3390/nano9091340 - 19 Sep 2019

Cited by 11 | Viewed by 3211

Abstract

Carbon nanomaterials are widely studied and applied nowadays, with annual production increasing. After entering the environment, the complete degradation of these carbon nanomaterials by microorganisms is proposed as an effective approach for detoxification and remediation. In this study, we evaluated the degradation of [...] Read more.

Carbon nanomaterials are widely studied and applied nowadays, with annual production increasing. After entering the environment, the complete degradation of these carbon nanomaterials by microorganisms is proposed as an effective approach for detoxification and remediation. In this study, we evaluated the degradation of pristine multiwalled carbon nanotubes (p-MWCNTs) and oxidized multiwalled carbon nanotubes (o-MWCNTs) by the white rot fungus Phanerochaete chrysosporium, which is a powerful decomposer in the carbon cycle and environmental remediation. Both p-MWCNTs and o-MWCNTs were partially oxidized by P. chrysosporium as indicated by the addition of oxygen atoms to the carbon skeleton in the forms of C=O and O–H bonds. The fungal oxidation led to the shortening of MWCNTs, where precipitated o-MWCNTs showed more short tubes. During the transformation, the defects on the tubes became detached from the carbon skeleton, resulting in decreases of the I_D/I_G (intensity of D-band/ intensity of G-band) values in Raman spectra. The transformation mechanism was attributed to the enzymatic degradation by laccase and manganese peroxidase excreted by P. chrysosporium. The results collectively indicated that MWCNTs could be transformed by P. chrysosporium, but complete degradation could not be achieved in a short time period. The implications on the environmental risks of carbon nanomaterials are discussed. Full article

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Full article ">Figure 1
TEM images of pristine multiwalled carbon nanotubes (p-MWCNTs) after the incubation with P. chrysosporium. (a) As-prepared p-MWCNTs; (b) wrapped p-MWCNTs at 3 d; (c) wrapped p-MWCNTs at 7 d; (d) wrapped p-MWCNTs at 14 d; (e) wrapped p-MWCNTs at 30 d; (f) precipitated p-MWCNTs at 3 d; (g) precipitated p-MWCNTs at 7 d; (h) precipitated p-MWCNTs at 14 d; (i) precipitated p-MWCNTs at 30 d. Shortened p-MWCNTs are indicated by red arrows. Full article ">Figure 2
TEM images of oxidized MWCNTs (o-MWCNTs) after the incubation with P. chrysosporium. (a) As-prepared o-MWCNTs; (b) wrapped o-MWCNTs at 3 d; (c) wrapped o-MWCNTs at 7 d; (d) wrapped o-MWCNTs at 14 d; (e) wrapped o-MWCNTs at 30 d; (f) precipitated o-MWCNTs at 3 d; (g) precipitated o-MWCNTs at 7 d; (h) precipitated o-MWCNTs at 14 d; (i) precipitated o-MWCNTs at 30 d. Shortened o-MWCNTs are circled in red. Full article ">Figure 3
Chemical components of MWCNTs after the incubation with P. chrysosporium. (a) Wrapped p-MWCNTs; (b) precipitated p-MWCNTs; (c) wrapped o-MWCNTs; (d) precipitated o-MWCNTs. Full article ">Figure 4
Raman spectra of MWCNTs after the incubation with P. chrysosporium. (a) Wrapped p-MWCNTs; (b) precipitated p-MWCNTs; (c) wrapped o-MWCNTs; (d) precipitated o-MWCNTs. Box-and-whisker plot shows the minimum and maximum (whisker bottom and top), first and third quartiles (box bottom and top), median (line inside box), and mean (square inside box) of ID/IG (intensity of D-band/ intensity of G-band) values (n = 20). ** p < 0.01 when compared to the 0 d samples. Full article ">Figure 5
IR spectra of MWCNTs after the incubation with P. chrysosporium. (a) Wrapped p-MWCNTs; (b) precipitated p-MWCNTs; (c) wrapped o-MWCNTs; (d) precipitated o-MWCNTs. Full article ">Figure 6
Laccase (Lac) activity (a) and manganese peroxidase (MnP) activity (b) of P. chrysosporium. Full article ">

13 pages, 5416 KiB

Open AccessArticle

TiO₂ Coated ZnO Nanorods by Mist Chemical Vapor Deposition for Application as Photoanodes for Dye-Sensitized Solar Cells

by Qiang Zhang and Chaoyang Li

Nanomaterials 2019, 9(9), 1339; https://doi.org/10.3390/nano9091339 - 19 Sep 2019

Cited by 37 | Viewed by 5479

Abstract

In this study, a mist chemical vapor deposition method was applied to create a coating of titanium dioxide particles in order to fabricate ZnO/TiO₂ core–shell nanostructures. The thin layers of titanium dioxide on the zinc oxide nanorods were uniform and confirmed as [...] Read more.

In this study, a mist chemical vapor deposition method was applied to create a coating of titanium dioxide particles in order to fabricate ZnO/TiO₂ core–shell nanostructures. The thin layers of titanium dioxide on the zinc oxide nanorods were uniform and confirmed as pure anatase phase. The morphological, structural, optical and photoluminescence properties of the ZnO/TiO₂ core–shell structures were influenced by coating time. For instance, the crystallinity of the titanium dioxide increased in accordance with an increase in the duration of the coating time. Additionally, the thickness of the titanium dioxide layer gradually increased with the coating time, resulting in an increased surface area. The transmittance of the arrayed ZnO/TiO₂ core–shell structures was 65% after 15 min of coating. The obtained ZnO/TiO₂ core–shell nanostructures demonstrated high potentiality to serve as photoanodes for application in dye-sensitized solar cells. Full article

(This article belongs to the Special Issue Nanoparticles for Photovoltaics)

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Mechanism of ZnO/TiO2 core–shell nanorod fabrication. Full article ">Figure 2
SEM images of the as-deposited ZnO nanorods (a) and ZnO nanorods coated with TiO2 by mist chemical vapor deposition (CVD) for (b) 30 s; (c) 2 min; (d) 5 min; (e) 10 min; and (f) 15 min ((1) top view and (2) cross section view). Full article ">Figure 3
The energy dispersive X-ray spectroscopy (EDS) elemental mapping images of the ZnO nanorods coated with TiO2 for 10 min ((a) a field emission scanning electron microscope (FESEM) image; (b) a zinc element mapping image; (c) a titanium element mapping image; and (d) an oxygen element mapping image). Full article ">Figure 4
Grazing incidence X-ray diffraction (GIXRD) patterns of the as-deposited ZnO nanorods and ZnO nanorods coated with TiO2 by mist CVD. Full article ">Figure 5
Raman spectra of the as-deposited ZnO nanorods and ZnO nanorods coated with TiO2 by mist CVD. Full article ">Figure 6
(a) Photoluminescence (PL) spectra of the TiO2 film on glass, as-deposited ZnO nanorods and ZnO nanorods coated with TiO2 by mist CVD; (b) PL spectra curve fitting of the as-deposited ZnO nanorods; and (c) PL spectra curve fitting of the ZnO nanorods coated with TiO2 for 10 min. Full article ">Figure 6 Cont.
(a) Photoluminescence (PL) spectra of the TiO2 film on glass, as-deposited ZnO nanorods and ZnO nanorods coated with TiO2 by mist CVD; (b) PL spectra curve fitting of the as-deposited ZnO nanorods; and (c) PL spectra curve fitting of the ZnO nanorods coated with TiO2 for 10 min. Full article ">Figure 7
(a) Transmission spectra of the as-deposited ZnO nanorods and ZnO nanorods coated with TiO2 by mist CVD; and (b) variation of (ahν)2 of the as-deposited ZnO nanorods and ZnO nanorods coated with TiO2 as a function of the photon energy (hν). Full article ">

13 pages, 4643 KiB

Open AccessArticle

A Facile Method of Preparing the Asymmetric Supercapacitor with Two Electrodes Assembled on a Sheet of Filter Paper

by Shasha Jiao, Tiehu Li, Chuanyin Xiong, Chen Tang, Alei Dang, Hao Li and Tingkai Zhao

Nanomaterials 2019, 9(9), 1338; https://doi.org/10.3390/nano9091338 - 19 Sep 2019

Cited by 15 | Viewed by 3574

Abstract

An asymmetric supercapacitor was prepared on a sheet of filter paper with two modified surfaces acting as electrodes in 1 M potassium hydroxide aqueous solution. By choosing carbon nanotubes and two different kinds of metal oxides (zinc oxide and ferro ferric oxide) as [...] Read more.

An asymmetric supercapacitor was prepared on a sheet of filter paper with two modified surfaces acting as electrodes in 1 M potassium hydroxide aqueous solution. By choosing carbon nanotubes and two different kinds of metal oxides (zinc oxide and ferro ferric oxide) as electrode materials, the asymmetric supercapacitor was successfully fabricated. The results showed that this device exhibited a wide potential window of 1.8 V and significantly improved electrochemical performances of its counterparts. Particularly, the one-sheet asymmetric supercapacitor demonstrated high energy density of 116.11 W h/kg and power density 27.48 kW/kg, which was attributed to the combined action and shortened distance between the two electrodes, respectively. Besides, it showed superior electrochemical cycling stability with 87.1% capacitance retention under room temperature. These outstanding results can not only give researchers new insights into compact energy storage systems, but they also provide a good prospect for flexible asymmetric supercapacitors. Full article

(This article belongs to the Special Issue Advances in Multifunctional Carbon-Based Nanocomposites: Synthesis, Characterization and Applications)

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15 pages, 4049 KiB

Open AccessArticle

Effect of Graphene Oxide Nano-Sheets on Structural, Morphological and Photocatalytic Activity of BiFeO₃-Based Nanostructures

by Syed Irfan, Guang-xing Liang, Fu Li, Yue-xing Chen, Syed Rizwan, Jingcheng Jin, Zheng Zhuanghao and Fan Ping

Nanomaterials 2019, 9(9), 1337; https://doi.org/10.3390/nano9091337 - 19 Sep 2019

Cited by 18 | Viewed by 4119

Abstract

Photocatalysts are widely used for the elimination of organic contaminants from waste-water and H₂ evaluation by water-splitting. Herein, the nanohybrids of lanthanum (La) and selenium (Se) co-doped bismuth ferrites with graphene oxide were synthesized. A structural analysis from X-ray diffraction confirmed the [...] Read more.

Photocatalysts are widely used for the elimination of organic contaminants from waste-water and H₂ evaluation by water-splitting. Herein, the nanohybrids of lanthanum (La) and selenium (Se) co-doped bismuth ferrites with graphene oxide were synthesized. A structural analysis from X-ray diffraction confirmed the transition of phases from rhombohedral to the distorted orthorhombic. Scanning electron microscopy (SEM) revealed that the graphene nano-sheets homogenously covered La–Se co-doped bismuth ferrites nanoparticles, particularly the (Bi_0.92La_0.08Fe_0.50Se_0.50O₃–graphene oxide) LBFSe50-G sample. Moreover, the band-gap nanohybrids of La–Se co-doped bismuth ferrites were estimated from diffuse reflectance spectra (DRS), which showed a variation from 1.84 to 2.09 eV, because the lowering of the band-gap can enhance photocatalytic degradation efficiency. Additionally, the photo-degradation efficiencies increased after the incorporation of graphene nano-sheets onto the La–Se co-doped bismuth ferrite. The maximum degradation efficiency of the LBFSe50-G sample was up to 80%, which may have been due to reduced band-gap and availability of enhanced surface area for incoming photons at the surface of the photocatalyst. Furthermore, photoluminescence spectra confirmed that the graphene oxide provided more electron-capturing sites, which decreased the recombination time of the photo-generated charge carriers. Thus, we can propose that the use of nanohybrids of La–Se co-doped bismuth ferrite with graphene oxide nano-sheets is a promising approach for both water-treatment and water-splitting, with better efficiencies of BiFeO₃. Full article

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The XRD pattern of La3+ and Se+4 co-doped BiFeO3 (BFO) nanohybrids with graphene oxide samples. Full article ">Figure 2
SEM micrographs of (a) Bi0.92La0.08FeO3–graphene oxide (LBF–G), (b) Bi0.92La0.08Fe0.90Se0.10O3–graphene oxide (LBFSe10–G), (c) Bi0.92La0.08Fe0.75Se0.25O3–graphene oxide (LBFSe25–G), (d) Bi0.92La0.08Fe0.50Se0.50O3–graphene oxide (LBFSe50–G), and (e) Bi0.92La0.08Fe0.50Se0.50O3–graphene oxide (LBFSe100–G). Full article ">Figure 3
X-ray photoelectron spectroscopy (XPS) spectra of LBFSe50–G: (a) Survey spectra, (b) oxygen-1s, (c) Bismuth-4f, and (d) carbon-1s. Full article ">Figure 4
XPS high resolution spectra of the LBFSe50–G system extracted from survey scan (a) La-3d (b) Fe-2p and (c) Se-3d. Full article ">Figure 5
The diffuse reflectance spectra of (a) LBF–G, (b) LBFSe10–G, (c) LBFSe25–G, (d) LBFSe50–G, and (e) LBFSe100–G. Full article ">Figure 6
Photoluminescence spectra of (a) LBFSe10–G, (b) LBFSe50–G, and (c) LBFSe100–G. Full article ">Figure 7
The photo-degradation efficiencies of Congo Red (CR) in the presence of, (a) BFO–G, (b) LBFSe10–G, (c) LBFSe25–G, (d) LBFSe50–G, and (e) LBFSe100–G. Full article ">Figure 8
The re-cyclic graph for LBFSe50–G after three cyclic runs under visible-light. Full article ">

12 pages, 7435 KiB

Open AccessArticle

Vertically Aligned NiCo₂O₄ Nanosheet-Encapsulated Carbon Fibers as a Self-Supported Electrode for Superior Li⁺ Storage Performance

by Yongchao Liu, Jintian Jiang, Yanyan Yuan, Qinglong Jiang and Chao Yan

Nanomaterials 2019, 9(9), 1336; https://doi.org/10.3390/nano9091336 - 18 Sep 2019

Cited by 27 | Viewed by 3387

Abstract

Binary transition metal oxides (BTMOs) have been explored as promising candidates in rechargeable lithium-ion battery (LIB) anodes due to their high specific capacity and environmental benignity. Herein, 2D ultrathin NiCo₂O₄ nanosheets vertically grown on a biomass-derived carbon fiber substrate (NCO [...] Read more.

Binary transition metal oxides (BTMOs) have been explored as promising candidates in rechargeable lithium-ion battery (LIB) anodes due to their high specific capacity and environmental benignity. Herein, 2D ultrathin NiCo₂O₄ nanosheets vertically grown on a biomass-derived carbon fiber substrate (NCO NSs/BCFs) were obtained by a facile synthetic strategy. The BCF substrate has superior flexibility and mechanical strength and thus not only offers a good support to NCO NSs/BCFs composites, but also provides high-speed paths for electron transport. Furthermore, 2D NiCo₂O₄ nanosheets grown vertically present a large contact area between the electrode and the electrolyte, which shortens the ions/electrons transport distance. The nanosheets structure can effectively limit the volume change derived from Li⁺ insertion and extraction, thus improving the stability of the electrode material. Therefore, the synthesized self-supporting NCO NSs/BCFs electrode displays excellent electrochemical performance, such as a large reversible capacity of 1128 mA·h·g⁻¹ after 80 cycles at a current density of 100 mA·g⁻¹ and a good rate capability of 818.5 mA·h·g⁻¹ at 1000 mA·g⁻¹. Undoubtedly, the cheap biomass carbon source and facile synthesis strategy here described can be extended to other composite materials for high-performance energy-storage and conversion devices. Full article

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Schematic illustration of the synthesis of the composite consisting of NiCo2O4 nanosheets grown vertically on a biomass-derived carbon fiber film (NCO NSs/BCFs). Full article ">Figure 2
(a) and (b) SEM images of the BCF substrate. Full article ">Figure 3
SEM images of the (a1–a3) NCO NSs/BCFs-6h; (b1–b3) NCO NSs/BCFs-8h; (c1–c3) NCO NSs/BCFs-10h; (d) EDS elemental mapping of Ni, Co, and O for NCO NSs/BCFs-10h. Full article ">Figure 4
(a) Raman spectra of BCFs; (b) XRD pattern of NCO NSs/BCFs; (c) XPS survey spectra of NCO NSs/BCFs; High-resolution (d) Ni 2p; (e) Co 2p; (f) O 1s XPS spectrum of NCO NSs/BCFs. Full article ">Figure 5
CV curves of (a) BCFs and (b) NCO NSs/BCFs; galvanostatic charge–discharge (GCD) profiles of (c) BCFs and (d) NCO NSs/BCFs; cycle performance of (e) BCFs and (f) NCO NSs/BCFs composite; (g) rate performance; (h) long cycle performance and corresponding coulombic efficiency of NCO NSs/BCFs-8h. Full article ">Figure 6
Nyquist plots of (a) BCFs; (b) NCO NSs/BCFs composite. Full article ">Figure 7
Schematic diagram of the self-supported NCO NSs/BCFs electrode. Full article ">

12 pages, 2537 KiB

Open AccessArticle

A Label-Free Electrochemical Immunosensor for Detection of the Tumor Marker CA242 Based on Reduced Graphene Oxide-Gold-Palladium Nanocomposite

by Xin Du, Xiaodi Zheng, Zhenhua Zhang, Xiaofan Wu, Lei Sun, Jun Zhou and Min Liu

Nanomaterials 2019, 9(9), 1335; https://doi.org/10.3390/nano9091335 - 18 Sep 2019

Cited by 17 | Viewed by 3508

Abstract

As a tumor marker, carbohydrate antigen 24-2 (CA242) is a highly accurate and specific diagnostic indicator for monitoring pancreatic and colorectal cancers. The goal of this study was to create a novel label-free electrochemical immunosensor using a nanocomposite glassy carbon electrode for the [...] Read more.

As a tumor marker, carbohydrate antigen 24-2 (CA242) is a highly accurate and specific diagnostic indicator for monitoring pancreatic and colorectal cancers. The goal of this study was to create a novel label-free electrochemical immunosensor using a nanocomposite glassy carbon electrode for the detection of CA242. Graphene oxide (GO) and polyvinyl pyrrolidone were chosen as the dopants for the preparation of a high-performance reduced-GO-gold-palladium (rGO-Au-Pd) nanocomposite. RGO-Au-Pd was characterized using X-ray diffraction and transmission electron microscopy, revealing that the material exhibited superior electrochemical redox activity and electron transfer ability. The effects of the synthesis method, material concentration, reduction cycle, and pH were investigated to optimize the performance of the immunosensor. As a result of the catalytic activity and biocompatibility of rGO-Au-Pd, the prepared CA242 immunosensor displayed a wide linear range of detection from 0.001 U/mL to 10,000 U/mL with a detection limit of 1.54 × 10⁻³ U/mL and a sensitivity of 4.24 μA (log₁₀C_CA242)⁻¹. More importantly, the immunosensor exhibited satisfactory reproducibility and selectivity when detected CA242 in PBS or human serum. The results of our study provide a platform for the development of novel bioassays for use in early cancer diagnosis and promote the application of biosensing technology in the medical field. Full article

(This article belongs to the Special Issue Biosensors Based on Nanostructure Materials)

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16 pages, 3368 KiB

Open AccessArticle

Ni_0.5Cu_0.5Co₂O₄ Nanocomposites, Morphology, Controlled Synthesis, and Catalytic Performance in the Hydrolysis of Ammonia Borane for Hydrogen Production

by Yufa Feng, Jin Zhang, Huilong Ye, Liling Li, Huize Wang, Xian Li, Xibin Zhang and Hao Li

Nanomaterials 2019, 9(9), 1334; https://doi.org/10.3390/nano9091334 - 18 Sep 2019

Cited by 25 | Viewed by 3068

Abstract

The catalytic hydrolysis of ammonia borane (AB) is a promising route to produce hydrogen for mobile hydrogen‒oxygen fuel cells. In this study, we have successfully synthesized a variety of Ni_0.5Cu_0.5Co₂O₄ nanocomposites with different morphology, including nanoplatelets, [...] Read more.

The catalytic hydrolysis of ammonia borane (AB) is a promising route to produce hydrogen for mobile hydrogen‒oxygen fuel cells. In this study, we have successfully synthesized a variety of Ni_0.5Cu_0.5Co₂O₄ nanocomposites with different morphology, including nanoplatelets, nanoparticles, and urchin-like microspheres. The catalytic performance of those Ni_0.5Cu_0.5Co₂O₄ composites in AB hydrolysis is investigated. The Ni_0.5Cu_0.5Co₂O₄ nanoplatelets show the best catalytic performance despite having the smallest specific surface area, with a turnover frequency (TOF) of 80.2 mol_hydrogen·min⁻¹·mol⁻¹_cat. The results reveal that, in contrast to the Ni_0.5Cu_0.5Co₂O₄ nanoparticles and microspheres, the Ni_0.5Cu_0.5Co₂O₄ nanoplatelets are more readily reduced, leading to the fast formation of active species for AB hydrolysis. These findings provide some insight into the design of high-performance oxide-based catalysts for AB hydrolysis. Considering their low cost and high catalytic activity, Ni_0.5Cu_0.5Co₂O₄ nanoplatelets are a strong candidate catalyst for the production of hydrogen through AB hydrolysis in practical applications. Full article

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10 pages, 1386 KiB

Open AccessArticle

Gold@Silica Nanoparticles Functionalized with Oligonucleotides: A Prominent Tool for the Detection of the Methylated Reprimo Gene in Gastric Cancer by Dynamic Light Scattering

by María José Marchant, Leda Guzmán, Alejandro H. Corvalán and Marcelo J. Kogan

Nanomaterials 2019, 9(9), 1333; https://doi.org/10.3390/nano9091333 - 18 Sep 2019

Cited by 11 | Viewed by 3870

Abstract

Reprimo (RPRM) is a tumor suppressor gene involved in the development of gastric cancer. Hypermethylation of the RPRM promoter region has been found in tumor tissue and plasma samples from patients with gastric cancer. These findings suggest that circulating methylated DNA [...] Read more.

Reprimo (RPRM) is a tumor suppressor gene involved in the development of gastric cancer. Hypermethylation of the RPRM promoter region has been found in tumor tissue and plasma samples from patients with gastric cancer. These findings suggest that circulating methylated DNA of RPRM could be a candidate for a noninvasive detection of gastric cancer. We designed a nanosystem based on the functionalization of silica coated gold nanoparticles with oligonucleotides that recognize a specific DNA fragment of the RPRM promoter region. The functionality of the oligonucleotide on the surface of the nanoparticle was confirmed by polymerase chain reaction (PCR). The nanoparticles were incubated with a synthetic DNA fragment of methylated DNA of RPRM and changes in the size distribution after hybridization were evaluated by dynamic light scattering (DLS). A difference in the size distribution of nanoparticles hybridized with genomic DNA from the KATO III gastric cancer cell line was observed when was compared with DNA from the GES-1 normal cell line. These results showed that this nanosystem may be a useful tool for the specific and sensitive detection of methylated DNA of RPRM in patients at risk of developing gastric cancer. Full article

(This article belongs to the Special Issue Functionalized Gold Nanoparticles: Synthesis, Properties and Biomedical Applications)

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Synthesis of gold nanoparticles by reduction with citrate. (a) Absorption spectrum of the AuNPs (40 nm) that exhibit a maximum absorption of 528 nm. The histogram in (a) shows the distribution of the sizes obtained by STEM with an average size of 46 ± 7 nm; (b) STEM image of 40 nm AuNPs. The bar corresponds to 100 nm. Full article ">Figure 2
Characterization of AuNPs coated with silica and functionalized with the oligonucleotide. (a) Visible spectra of the nanoparticles obtained subsequent to each of the modifications. A slight displacement was observed due to the silica coating and functionalization with the oligonucleotide; (b) STEM image showing the nanoparticles obtained after the silica coating. The bar corresponds to 50 nm. Full article ">Figure 3
Methylated DNA of RPRM capture by hybridization and the PCR reaction with Au@SiO2–COOH-oligo. Analyzed by 2% agarose gel electrophoresis and staining with ethidium bromide. M: Molecular Weight 50 bp NEB®. bp: base pairs. Full article ">Figure 4
The percentage of Au@SiO2–COOH-oligo nanoparticles after the hybridization assay with the synthetic fragment of the methylated DNA of RPRM. The average ± SD was plotted for all replicates analyzed. **** p < 0.0001. Full article ">Figure 5
Percent of Au@SiO2–COOH-oligo nanoparticles after the hybridization assay with DNA from two different cell lines. Average ± SD was plotted for all replicates analyzed. ns: not significant; **** p < 0.0001. Full article ">Scheme 1
Schematic illustration and dynamic light scattering (DLS) description of the effect of hybridization of AuNPs functionalized with oligonucleotides and DNA. Full article ">

9 pages, 10655 KiB

Open AccessArticle

Ultrafast Patterning Vertically Aligned Carbon Nanotube Forest on Al Foil and Si Substrate Using Chemical Vapor Deposition (CVD)

by Yan-Rui Li, Chin-Ping Huang, Chih-Chung Su and Shuo-Hung Chang

Nanomaterials 2019, 9(9), 1332; https://doi.org/10.3390/nano9091332 - 18 Sep 2019

Cited by 4 | Viewed by 3985

Abstract

This study introduces a method of patterning carbon nanotube (CNTs) forests that is both fast and simple. We found that, as commercially available oil-based markers undergo nanotube synthesis, a thin film forms that prevents the catalyst, ferrocene, from coming into contact with the [...] Read more.

This study introduces a method of patterning carbon nanotube (CNTs) forests that is both fast and simple. We found that, as commercially available oil-based markers undergo nanotube synthesis, a thin film forms that prevents the catalyst, ferrocene, from coming into contact with the surface of the test sample. This, thus, blocks CNT growth. Through further deduction, we used styrene maleic anhydride (SMA) to conduct CNT patterning, in addition to analyzing the relationship between the weight percent concentration of the SMA and the extent to which it blocked CNT growth. We developed two separate methods for applying ink to soft and hard substrates: one method involved ink printing and the other laser stripping. In the CNT pattern we produced, a minimum line width of around 10 µm was attained. Full article

(This article belongs to the Special Issue Carbon Nanotube: Synthesis, Characteristics and Applications)

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Synthesis setup and recipes for the experiment, which involved a three-step chemical vapor deposition (CVD) process. Full article ">Figure 2
(a–c) Transmission electron microscopy images show Fe particles along the length of the carbon nanotube (CNT). Full article ">Figure 3
(a) A film layer forms on ink-coated areas of the sample following CNT synthesis; the resulting morphology contrasts to the areas without ink. (b) Nanotubes grow under the film layer, rupture its surface, and continue growing upward. (c) Following synthesis, the area of the sample coated in ink is elevated by a CNT forest growing underneath it. Full article ">Figure 4
(a) At a styrene-maleic anhydride (SMA) concentration of 9.1 wt% nanotubes continue to grow, producing an unclear pattern. (b) At a concentration of 16.7 wt%, the pattern is clear and the covering holds. (c) Exposed to room temperature conditions, the film layer has already formed prior to CNT synthesis. Full article ">Figure 5
(a) Ink printing was used to pattern CNT forests on aluminium foil (b) and the horizontal and vertical stripe patterns from <a href="#nanomaterials-09-01332-f005" class="html-fig">Figure 5</a>a were observed via scanning electron microscopy (SEM) images. (c) Reducing line width caused ink splattering and diminished the ability of ink to block CNT forest growth. Full article ">Figure 6
(a) The process of patterning CNT forests on a silicon wafer using laser stripping. (b) SEM was used to observe a synthesized CNT forest pattern with a minimum line width of 10 µm. Full article ">

14 pages, 8955 KiB

Open AccessArticle

Mussel-Inspired Fabrication of SERS Swabs for Highly Sensitive and Conformal Rapid Detection of Thiram Bactericides

by Jun Liu, Tiantian Si, Lingzi Zhang and Zhiliang Zhang

Nanomaterials 2019, 9(9), 1331; https://doi.org/10.3390/nano9091331 - 17 Sep 2019

Cited by 26 | Viewed by 4336

Abstract

As an important sort of dithiocarbamate bactericide, thiram has been widely used for fruits, vegetables and mature crops to control various fungal diseases; however, the thiram residues in the environment pose a serious threat to human health. In this work, silver nanoparticles (AgNPs) [...] Read more.

As an important sort of dithiocarbamate bactericide, thiram has been widely used for fruits, vegetables and mature crops to control various fungal diseases; however, the thiram residues in the environment pose a serious threat to human health. In this work, silver nanoparticles (AgNPs) were grown in-situ on cotton swab (CS) surfaces, based on the mussel-inspired polydopamine (PDA) molecule and designed as highly sensitive surface-enhanced Raman scattering (SERS) swabs for the conformal rapid detection of bactericide residues. With this strategy, the obtained CS@PDA@AgNPs swabs demonstrated highly sensitive and reproducible Raman signals toward Nile blue A (NBA) probe molecules, and the detection limit was as low as 1.0 × 10⁻¹⁰ M. More critically, these CS@PDA@AgNPs swabs could be served as flexible SERS substrates for the conformal rapid detection of thiram bactericides from various fruit surfaces through a simple swabbing approach. The results showed that the detection limit of thiram residues from pear, grape and peach surfaces was approximately down to the level of 0.12 ng/cm², 0.24 ng/cm² and 0.15 ng/cm² respectively, demonstrating a high sensitivity and excellent reliability toward dithiocarbamate bactericides. Not only could these SERS swabs significantly promote the collection efficiency of thiram residues from irregular shaped matrices, but they could also greatly enhance the analytical sensitivity and reliability, and would have great potential for the on-site detection of residual bactericides in the environment and in bioscience fields. Full article

(This article belongs to the Special Issue Surface Enhanced Raman Spectroscopy in Nano-World)

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The schematic of the fabrication of CS@PDA@AgNPs swabs for the conformal rapid SERS detection of thiram bactericide residues. Full article ">Figure 2
SEM images of the (a–c) original cotton swabs, (d–f) CS@PDA swabs and (g–i) CS@PDA@AgNPs swabs, respectively. Full article ">Figure 3
(a) XPS survey of the original cotton swabs, CS@PDA swabs and CS@PDA@AgNPs swabs. (b) High-resolution Ag3d spectrum in the CS@PDA@AgNPs swabs. (c) Narrow-scan XPS spectra of C1s in the CS@PDA@AgNPs swabs. (d) The changes of the N1s spectrum in the original cotton swabs, CS@PDA swabs and CS@PDA@AgNPs swabs. Full article ">Figure 4
SEM images of the CS@PDA@AgNPs swabs after reacting with [Ag(NH3)2]+ anions for (a) 4 h, (b) 8 h and (c) 12 h. (d–f) The respective SERS spectra of NBA collected on the 4 h, 8 h and 12 h CS@PDA@AgNPs swabs. Full article ">Figure 5
(a) The Raman spectra of the NBA probe molecules at different concentrations on the CS@PDA@AgNPs swabs. (b) The relationship between the signal intensity at 591 cm−1 of the NBA molecules and the corresponding logarithmic concentration. (c) The SERS homogeneity of the CS@PDA@AgNPs swabs from 20 randomly selected points. (d) The Raman intensity distribution of the NBA molecules at 591 cm−1 collected from 20 randomly selected points. Full article ">Figure 6
The SERS spectra of thiram with different concentrations collected by CS@PDA@AgNPs swabs through swabbing extraction on (a) pear, (b) grape and (c) peach surfaces. The relationship between the SERS peak intensity at 1380 cm−1 and the corresponding logarithmic concentration of thiram molecules on (d) pear, (e) grape and (f) peach surfaces through a swabbing extraction. Full article ">Figure 7
(a) The SERS homogeneity of thiram on the CS@PDA@AgNPs swabs from 10 random spots. (b) The corresponding intensity variation at 1380 cm−1 in the histogram. (c) The Raman spectrum of thiram from the CS@PDA@AgNPs swabs stored for 0–5 months. (d) The corresponding intensity variation at 1380 cm−1 in the histogram. Full article ">

23 pages, 8887 KiB

Open AccessReview

Carbon-Based Nanomaterials in Sensors for Food Safety

by Mingfei Pan, Zongjia Yin, Kaixin Liu, Xiaoling Du, Huilin Liu and Shuo Wang

Nanomaterials 2019, 9(9), 1330; https://doi.org/10.3390/nano9091330 - 17 Sep 2019

Cited by 79 | Viewed by 5896

Abstract

Food safety is one of the most important and widespread research topics worldwide. The development of relevant analytical methods or devices for detection of unsafe factors in foods is necessary to ensure food safety and an important aspect of the studies of food [...] Read more.

Food safety is one of the most important and widespread research topics worldwide. The development of relevant analytical methods or devices for detection of unsafe factors in foods is necessary to ensure food safety and an important aspect of the studies of food safety. In recent years, developing high-performance sensors used for food safety analysis has made remarkable progress. The combination of carbon-based nanomaterials with excellent properties is a specific type of sensor for enhancing the signal conversion and thus improving detection accuracy and sensitivity, thus reaching unprecedented levels and having good application potential. This review describes the roles and contributions of typical carbon-based nanomaterials, such as mesoporous carbon, single- or multi-walled carbon nanotubes, graphene and carbon quantum dots, in the construction and performance improvement of various chemo- and biosensors for various signals. Additionally, this review focuses on the progress of applications of this type of sensor in food safety inspection, especially for the analysis and detection of all types of toxic and harmful substances in foods. Full article

(This article belongs to the Special Issue Carbon-Based Nanomaterials for (Bio)Sensors Development)

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25 pages, 2081 KiB

Open AccessReview

Developing Protein-Based Nanoparticles as Versatile Delivery Systems for Cancer Therapy and Imaging

by Febrina Sandra, Nisar Ul Khaliq, Anwar Sunna and Andrew Care

Nanomaterials 2019, 9(9), 1329; https://doi.org/10.3390/nano9091329 - 16 Sep 2019

Cited by 50 | Viewed by 8466

Abstract

In recent years, it has become apparent that cancer nanomedicine’s reliance on synthetic nanoparticles as drug delivery systems has resulted in limited clinical outcomes. This is mostly due to a poor understanding of their “bio–nano” interactions. Protein-based nanoparticles (PNPs) are rapidly emerging as [...] Read more.

In recent years, it has become apparent that cancer nanomedicine’s reliance on synthetic nanoparticles as drug delivery systems has resulted in limited clinical outcomes. This is mostly due to a poor understanding of their “bio–nano” interactions. Protein-based nanoparticles (PNPs) are rapidly emerging as versatile vehicles for the delivery of therapeutic and diagnostic agents, offering a potential alternative to synthetic nanoparticles. PNPs are abundant in nature, genetically and chemically modifiable, monodisperse, biocompatible, and biodegradable. To harness their full clinical potential, it is important for PNPs to be accurately designed and engineered. In this review, we outline the recent advancements and applications of PNPs in cancer nanomedicine. We also discuss the future directions for PNP research and what challenges must be overcome to ensure their translation into the clinic. Full article

(This article belongs to the Special Issue Optical Nanomaterials for Diagnosis and Therapy)

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The three phases of PNP delivery and the pathophysiological barriers they encounter after systemic administration (i.e., intravenous injection). Phase I: ‘Circulation.’ After entering the bloodstream, protein corona formation on PNPs can evoke recognition by the mononuclear phagocytic system (MPS), leading to their clearance via MPS-rich organs; e.g., liver, kidney, and spleen. Therefore, to enable therapeutic concentrations of the NDDS to interact with tumors, PNPs must evade the MPS, while retaining their stability during blood circulation. Phase II: ‘Accumulation and Penetration.’ PNPs must extravasate from the bloodstream via leaky vasculature into the tumor, where they must overcome physical and physiological barriers to penetrate deep into the tumor microenvironment. Phase III: ‘Internalization and Cargo Release.’ Following endocytosis, PNPs are trafficked into endo/lysosomes and finally degraded to release their therapeutic cargo. Depending on their cargo’s mode-of-action, PNPs may need to escape (and avoid degradation) from endo/lysosomal compartments to the cytosol. TAM= tumor-associated macrophages; EPR effect = enhanced permeability and retention effect; ECM = extracellular matrix; IFP = interstitial fluid pressure. Full article ">Figure 2
Illustration showing the various outer surface modifications used to make ‘stealth’ PNPs, and/or enhance their cellular targeting, uptake, and intracellular trafficking. Full article ">Figure 3
Examples of PNP-mediated drug delivery for different cancer therapies. (Left panel) Anti-hypoxia therapy: ferritin-mediated delivery of the HIF-1α inhibitor, Acriflavine (AF). (A) AF is encapsulated within PEGylated ferritin (FTn) via assembly-disassembly method. (B) Fluorescence microscopy showed that the PEGylation density of FTn affected its ability to penetrate 3D lung cancer tumor spheroids. (C) FTn with a PEG coverage of ≥75% (PEG–FTn75%) showed deep penetration and accumulation within inner hypoxic areas of tumor spheroids. (D) Tumor sections from orthotropic lung tumor-bearing mice showed that PEG–FTn75% successfully penetrated inner hypoxic areas in tumors after systemic injection. (E) Delivery of AF using PEG–FTn75% significantly reduce HIF5-1α, LOX, and VEGF expression in vivo. Adapted from [<a href="#B27-nanomaterials-09-01329" class="html-bibr">27</a>], with permission from American Chemical Society, 2019. (Right Panel) Photodynamic therapy (PDT): ferritin-mediated delivery of photosensitizers for photodynamic therapy. (F) Ferritin is used to target the delivery of photosensitizers into tumors to mediate PDT which kills cancer-associated fibroblasts (CAFs), weakens the extracellular matrix (ECM), and enhances the penetration of nanoparticles into the tumor. (G) ZnF16PC-loaded chain variable fragment (scFv)–ferritin for targeted PDT (H) Both the free photosensitizer ZnF16PC and ZnF16PC-loaded scFv–ferritin produced similar amounts of reactive oxygen species ROS upon irradiation in time dependent manner (I) Bilateral tumor bearing mice were used to compare the effect of PDT on the reduction of collagen level in the tumor ECM. The tumor covered with aluminum foil was not irradiated. (J) Tumor section from irradiated tumor and non-irradiated tumor. ECM levels were decreased by PDT in the irradiated tumor (Mason’s trichome staining). (K) Increased accumulation of 50 nm quantum dots (QDs) in the irradiated tumor after PDT indicated that the decrease in ECM improves the penetration and accumulation of the NDDS in tumor tissue (Maestro II imaging system). Adapted from [<a href="#B31-nanomaterials-09-01329" class="html-bibr">31</a>], with permission from American Chemical Society, 2018. Full article ">Figure 4
Examples of PNP-mediated delivery of biotherapeutics and imaging agents. (Upper panel) TRAIL-based therapy: PVX-mediated delivery of the anti-cancer biotherapeutic HisTRAIL. (A) Schematic showing PVX–HisTRAIL-induced apoptosis via caspase dependent pathway. (B) IC50 of free His-TRAIL and PVX–HisTRAIL against various cancer cell types (C). PVX–HisTRAIL activated caspase 8 and caspase 3/7. (D,E) In comparison to free HisTRAIL, PVX–HisTRAIL significantly regressed tumor growth in tumor-bearing mice after 30 days. Adapted from [<a href="#B24-nanomaterials-09-01329" class="html-bibr">24</a>], with permission from American Chemical Society, 2019. (Lower Panel) Magnetic resonance imaging (MRI): Hsp-mediated delivery of the MRI contrast agent Gd–DTPA. (F) Design of Hsp variants for Gd–DTPA delivery. (G) Hsp was modified with a C-terminal iRGD to target pancreatic cancer cells. To generate variants of different sizes, hydrophobic peptides repeats were attached at the N-terminus of Hsp, resulting in: 1-nanocage, 2-nanocage, 3-nanocage, and 4-nanocage. (H) Relaxivity values (at 1.5 Tesla) for each iRGD–Hsp variant of free Gd–DTPA, in vitro. (I,J) In vivo MRI images (9.4 T) in transgenic mice bearing pancreatic tumors 6h after IV injection. The ‘4-nanocage’ variant showed a significantly higher tumor-to-normal MRI contrast ratio than free Gd–DTPA. Adapted from [<a href="#B38-nanomaterials-09-01329" class="html-bibr">38</a>], with permission from Elsevier, 2018. Full article ">

12 pages, 2572 KiB

Open AccessArticle

Solution-Processed PEDOT:PSS/MoS₂ Nanocomposites as Efficient Hole-Transporting Layers for Organic Solar Cells

by Madeshwaran Sekkarapatti Ramasamy, Ka Yeon Ryu, Ju Won Lim, Asia Bibi, Hannah Kwon, Ji-Eun Lee, Dong Ha Kim and Kyungkon Kim

Nanomaterials 2019, 9(9), 1328; https://doi.org/10.3390/nano9091328 - 16 Sep 2019

Cited by 24 | Viewed by 5695

Abstract

An efficient hole-transporting layer (HTL) based on functionalized two-dimensional (2D) MoS₂-poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) composites has been developed for use in organic solar cells (OSCs). Few-layer, oleylamine-functionalized MoS₂ (FMoS₂) nanosheets were prepared via a simple and cost-effective solution-phase exfoliation method; [...] Read more.

An efficient hole-transporting layer (HTL) based on functionalized two-dimensional (2D) MoS₂-poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) composites has been developed for use in organic solar cells (OSCs). Few-layer, oleylamine-functionalized MoS₂ (FMoS₂) nanosheets were prepared via a simple and cost-effective solution-phase exfoliation method; then, they were blended into PEDOT:PSS, a conducting conjugated polymer, and the resulting hybrid film (PEDOT:PSS/FMoS₂) was tested as an HTL for poly(3-hexylthiophene):[6,6]-phenyl-C₆₁-butyric acid methyl ester (P3HT:PCBM) OSCs. The devices using this hybrid film HTL showed power conversion efficiencies up to 3.74%, which is 15.08% higher than that of the reference ones having PEDOT:PSS as HTL. Atomic force microscopy and contact angle measurements confirmed the compatibility of the PEDOT:PSS/FMoS₂ surface for active layer deposition on it. The electrical impedance spectroscopy analysis revealed that their use minimized the charge-transfer resistance of the OSCs, consequently improving their performance compared with the reference cells. Thus, the proposed fabrication of such HTLs incorporating 2D nanomaterials could be further expanded as a universal protocol for various high-performance optoelectronic devices. Full article

(This article belongs to the Special Issue Advances in Emerging Solar Cells)

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Fabrication process for poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/oleylamine-functionalized MoS2 (FMoS2) hybrid hole-transporting layer (HTL) for organic solar cells. Full article ">Figure 2
(a) Raman spectra of bulk and oleylamine-functionalized MoS2 (FMoS2). (b) Ultraviolet–visible light absorption spectrum of FMoS2. (c,d) Transmission electron microscopy images of FMoS2 nanosheets. Full article ">Figure 3
(a) Current density–voltage curves, (b) external quantum efficiency (EQE) profiles, (c) power conversion efficiencies (PCE), (d) short-circuit current density (Jsc), (e) fill factor, and (f) open-circuit voltage (Voc) values of organic solar cells based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and PEDOT:PSS/oleylamine-functionalized MoS2 (FMoS2) as hole-transporting layers. The reported average PCE values are extracted from nine identical cells for each sample. Full article ">Figure 4
Grazing-incidence wide-angle X-ray scattering diffraction patterns of poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester thin films deposited on (a) poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and PEDOT:PSS combined with (b) 5, (c) 20, and (d) 50 µL of oleylamine-functionalized MoS2. Full article ">Figure 5
(a) In-plane and (b) out-of-plane spectra of poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester thin films deposited on poly (3,4-ethylendioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) and PEDOT:PSS combined with 5, 20, and 50 µL of oleylamine-functionalized MoS2 samples obtained from grazing-incidence wide-angle X-ray scattering. Full article ">Figure 6
Electrical impedance spectra of organic solar cells based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and PEDOT:PSS/oleylamine-functionalized MoS2 (5 µL) (PEDOT:PSS/FMoS2(5)) as hole-transportation layer. Full article ">

11 pages, 2820 KiB

Open AccessArticle

Strain-Mediated Bending of InP Nanowires through the Growth of an Asymmetric InAs Shell

by Ya’akov Greenberg, Alexander Kelrich, Shimon Cohen, Sohini Kar-Narayan, Dan Ritter and Yonatan Calahorra

Nanomaterials 2019, 9(9), 1327; https://doi.org/10.3390/nano9091327 - 16 Sep 2019

Cited by 9 | Viewed by 3573

Abstract

Controlling nanomaterial shape beyond its basic dimensionality is a concurrent challenge tackled by several growth and processing avenues. One of these is strain engineering of nanowires, implemented through the growth of asymmetrical heterostructures. Here, we report metal–organic molecular beam epitaxy of bent InP/InAs [...] Read more.

Controlling nanomaterial shape beyond its basic dimensionality is a concurrent challenge tackled by several growth and processing avenues. One of these is strain engineering of nanowires, implemented through the growth of asymmetrical heterostructures. Here, we report metal–organic molecular beam epitaxy of bent InP/InAs core/shell nanowires brought by precursor flow directionality in the growth chamber. We observe the increase of bending with decreased core diameter. We further analyze the composition of a single nanowire and show through supporting finite element simulations that strain accommodation following the lattice mismatch between InP and InAs dominates nanowire bending. The simulations show the interplay between material composition, shell thickness, and tapering in determining the bending. The simulation results are in good agreement with the experimental bending curvature, reproducing the radius of 4.3 µm (±10%), for the 2.3 µm long nanowire. The InP core of the bent heterostructure was found to be compressed at about 2%. This report provides evidence of shape control and strain engineering in nanostructures, specifically through the exchange of group-V materials in III–V nanowire growth. Full article

(This article belongs to the Special Issue Novel Synthesis Strategies and Phenomena in Low-Dimensional Structures Like Nanowires and Thin Films)

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(a) Schematic of the metal–organic molecular beam epitaxy (MOMBE) growth chamber showing the vertical tube used to introduce group-III growth species to the system and the 30° inclined tube used for group-V species. (b) Schematic of the growth procedure of InP/InAs nanowire (NW) heterostructures and the resulting bent NW. (c) Schematic of the growth sequence illustrating the nominal NW form, where InAs (red arrows) was introduced four times following the growth of an InP NW. Note that the actual NW shape is significantly different. Full article ">Figure 2
SEM images of bent heterostructure grown from catalysts of various pitch and diameter, with diameter 1 (~38 nm) and diameter 2 (~43 nm), and wire pitch of (a,b) 2 µm, (c,d) 0.25 µm, (e) 1 µm, and (f) 0.5 µm. The main finding was the reduction of bending with increasing NW density and diameter. Full article ">Figure 3
Homoepitaxial growth of III–V NWs. Left hand side, InP NWs on InP <111> (following [<a href="#B38-nanomaterials-09-01327" class="html-bibr">38</a>]) and right hand side, InAs. This type of growth did not result in any bending or radial asymmetry, demonstrating that bending and asymmetry arise due to heterostructure growth. Full article ">Figure 4
(a) TEM image of a bent InP–InAs heterostructure NW. (b,c) Energy-dispersive X-ray (EDX) analysis of the wire cross section at (b) wire base and (c) wire middle. Arrows show scan direction. (d,e) High-resolution TEM (HRTEM) scans of NW heterostructures showing further bending in addition to the creation of axial InAs segments. Dashed lines are a guide to the eye. Full article ">Figure 5
COMSOL simulation of the asymmetric shell-induced bending. (a) Top view of the geometry; (b) relaxed (bent) NW, where displacement of the top was nearly 0.5 µm. The red point and arrow mark the clamping in the point-clamped case; (c) strain analysis of the simulated results, i.e., the surface-clamped tapered case (grey tinted row in <a href="#nanomaterials-09-01327-t001" class="html-table">Table 1</a>). The left-hand side shows x,y,z strains throughout the central ZX cross section, and the right-hand side shows the axial (z) strain throughout an XY cross section, with a dashed circle guiding the eye to the InP core. Overall, the NW was axially compressed and slightly strained radially following Poisson’s ratio. The scale bar is common to all cross sections. Full article ">

15 pages, 6569 KiB

Open AccessArticle

Buckling Behavior of Nanobeams Placed in Electromagnetic Field Using Shifted Chebyshev Polynomials-Based Rayleigh-Ritz Method

by Subrat Kumar Jena, Snehashish Chakraverty and Francesco Tornabene

Nanomaterials 2019, 9(9), 1326; https://doi.org/10.3390/nano9091326 - 16 Sep 2019

Cited by 26 | Viewed by 3836

Abstract

In the present investigation, the buckling behavior of Euler–Bernoulli nanobeam, which is placed in an electro-magnetic field, is investigated in the framework of Eringen’s nonlocal theory. Critical buckling load for all the classical boundary conditions such as “Pined–Pined (P-P), Clamped–Pined (C-P), Clamped–Clamped (C-C), [...] Read more.

In the present investigation, the buckling behavior of Euler–Bernoulli nanobeam, which is placed in an electro-magnetic field, is investigated in the framework of Eringen’s nonlocal theory. Critical buckling load for all the classical boundary conditions such as “Pined–Pined (P-P), Clamped–Pined (C-P), Clamped–Clamped (C-C), and Clamped-Free (C-F)” are obtained using shifted Chebyshev polynomials-based Rayleigh-Ritz method. The main advantage of the shifted Chebyshev polynomials is that it does not make the system ill-conditioning with the higher number of terms in the approximation due to the orthogonality of the functions. Validation and convergence studies of the model have been carried out for different cases. Also, a closed-form solution has been obtained for the “Pined–Pined (P-P)” boundary condition using Navier’s technique, and the numerical results obtained for the “Pined–Pined (P-P)” boundary condition are validated with a closed-form solution. Further, the effects of various scaling parameters on the critical buckling load have been explored, and new results are presented as Figures and Tables. Finally, buckling mode shapes are also plotted to show the sensitiveness of the critical buckling load. Full article

(This article belongs to the Special Issue Advanced Mechanical Modeling of Nanomaterials and Nanostructures)

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11 pages, 2930 KiB

Open AccessArticle

A Mechanochemical Route for ZnS Nanocrystals, and Batch Sorting along Size Distribution

by Pengfei Hu, Chen Xie, Zhihui Mao and Xue Liang

Nanomaterials 2019, 9(9), 1325; https://doi.org/10.3390/nano9091325 - 15 Sep 2019

Cited by 7 | Viewed by 2922

Abstract

The assistances of sodium dodecyl benzene sulfonate (SDBS) and aging treatment were introduced to further improve the room-temperature mechanochemical synthesis of the quantum-sized zinc sulfide (ZnS) nanocrystals. As a result, a green strategy for synthesizing the monodisperse nanocrystals with tunable size and crystallinity [...] Read more.

The assistances of sodium dodecyl benzene sulfonate (SDBS) and aging treatment were introduced to further improve the room-temperature mechanochemical synthesis of the quantum-sized zinc sulfide (ZnS) nanocrystals. As a result, a green strategy for synthesizing the monodisperse nanocrystals with tunable size and crystallinity was developed, holding convenient, highly efficient and low pollution. Size evolution shows a gradually increasing trend along the aging-temperature. A model that the independent reaction cells constructed by SDBS-wrapped reactant packages (solid state vesicles, SSVs) for the confined growth of ZnS nanocrystals was proposed to access the formation mechanism of ZnS quantized crystal in a solid-state synthesis system. The band gaps and band-edge luminescent emissions of as-prepared ZnS nanocrystals experienced the size-dependent quantum confinement effect, while the trap-state emissions exhibited the lattice integrity-dependence. Furthermore, ZnS quantum-sized nanocrystals with narrower size distribution can be obtained by a batch-sorting process through adjusting the centrifugal speed. Full article

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An improved mechanochemical recipe for quantized structures. Full article ">Figure 2
X-ray diffraction patterns of zinc sulfide (ZnS) nanocrystals: a) ZnS quantum dots (Q-ZnS)-I (black curve), b) Q-ZnS-I′ (red curve), c) Q-ZnS-I″ (blue curve). Full article ">Figure 3
TEM and HRTEM images of representative nanocrystals of samples: a,a′) Q-ZnS-I; b,b′) Q-ZnS-I′; c,c′) Q-ZnS-I″, respectively. Full article ">Figure 4
FT-IR spectra of SDBS and Q-ZnS-I′. Full article ">Figure 5
a) Comparison of Ultraviolet-Visible (UV-Vis) and b) Photoluminescence (PL) spectra of three samples: Q-ZnS-I (blue symbol scatter), Q-ZnS-I′ (red symbol scatter), and Q-ZnS-I″ (black symbol scatter). The inset is the plots of (αhν)2 versus (hν) for three samples: Q-ZnS-I (blue), Q-ZnS-I′ (red), and Q-ZnS-I″ (black). The band gap values were estimated to be 4.85, 4.76, and 4.58 eV for Q-ZnS-I, Q-ZnS-I′, and Q-ZnS-I″, respectively. Full article ">Figure 6
TEM images and size distribution plots of the samples through the batch-sorting process: a,a′) Q-ZnS-I′-i (3000 rpm); b,b′) Q-ZnS-I′-ii (4000 rpm), respectively. c) UV-Vis and photoluminescence spectra of the batch-sorting sample Q-ZnS-I′-ii. Full article ">Scheme 1
Proposed formation mechanism of ZnS nanocrystals through sodium dodecyl benzene sulfonate (SDBS)-wrapped zinc acetate packages in the room-temperature mechanochemical route. Bottom: SEM and EDS-mapping characterizations for the SDBS-wrapped zinc acetate solid-state vesicle. Full article ">

9 pages, 2761 KiB

Open AccessArticle

SnSe₂ Quantum Dots: Facile Fabrication and Application in Highly Responsive UV-Detectors

by Xiangyang Li, Ling Li, Huancheng Zhao, Shuangchen Ruan, Wenfei Zhang, Peiguang Yan, Zhenhua Sun, Huawei Liang and Keyu Tao

Nanomaterials 2019, 9(9), 1324; https://doi.org/10.3390/nano9091324 - 15 Sep 2019

Cited by 18 | Viewed by 3933

Abstract

Synthesizing quantum dots (QDs) using simple methods and utilizing them in optoelectronic devices are active areas of research. In this paper, we fabricated SnSe₂ QDs via sonication and a laser ablation process. Deionized water was used as a solvent, and there were [...] Read more.

Synthesizing quantum dots (QDs) using simple methods and utilizing them in optoelectronic devices are active areas of research. In this paper, we fabricated SnSe₂ QDs via sonication and a laser ablation process. Deionized water was used as a solvent, and there were no organic chemicals introduced in the process. It was a facile and environmentally-friendly method. We demonstrated an ultraviolet (UV)-detector based on monolayer graphene and SnSe₂ QDs. The photoresponsivity of the detector was up to 7.5 × 10⁶ mAW⁻¹, and the photoresponse time was ~0.31 s. The n–n heterostructures between monolayer graphene and SnSe₂ QDs improved the light absorption and the transportation of photocarriers, which could greatly increase the photoresponsivity of the device. Full article

(This article belongs to the Special Issue Functional Nanostructures for Sensors, Optoelectronic Devices and Drug Delivery)

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Schematic show of the SnSe2 structure and the quantum dot (QD) fabrication process. Full article ">Figure 2
(a) TEM image of SnSe2 QDs with a centrifugal speed of 6000 rpm. The inset shows the detailed crystal structure of a single QD; (b) the size distribution of the SnSe2 QDs. Full article ">Figure 3
Spectroscopic characterizations. (a) XRD pattern of the SnSe2 bulk and QDs; (b) Raman spectra of the SnSe2 bulk and QDs; (c) absorption spectra of the SnSe2 QDs and nanosheet solutions; (d) TEM energy dispersive spectra (TEM-EDS) of the SnSe2 QDs. The inset shows the EDS of the TEM substrate without QDs. Full article ">Figure 4
(a) Schematic diagram of a graphene photodetector decorated with SnSe2 QDs; (b) Raman spectra of the pure graphene on a p+Si/SiO2 substrate; (c) the I–V curves for the single-layer graphene phototransistor in the dark and with illumination under zero-gate voltage (VG = 0 V); (d) transfer characteristics (IDS-VG, VDS = 0.5 V) of the phototransistor with and without SnSe2 QDs on the graphene film; (e) photocurrent and (f) responsivity of a SnSe2 QD-decorated graphene photodetector as functions of drain voltages at different illumination densities. The illumination wavelength is 405 nm. Full article ">Figure 5
(a) Transfer characteristics of a graphene photodetector decorated with SnSe2 quantum dots at different illumination densities (wavelength: 405 nm, VDS = 0.5 V); (b) horizontal shift of transfer curves as functions of illumination densities. The inset shows the charge transfer between SnSe2 QDs and graphene; (c) current response to on/off light illumination for several cycles; (d) photocurrent response time of the device. (VDS = 0.05 V, illumination density: 155.2 μW/cm 2). Full article ">Figure 6
The AFM images of SnSe2 QDs with different densities (a) 2 μL, (b) 6 μL, and (c) 12 μL. The insets show their height profiles. (d) The photocurrents with different SnSe2 QDs densities at the irradiation density of 350.0 μW/cm2. Full article ">

11 pages, 3177 KiB

Open AccessArticle

Amorphous Sb₂S₃ Nanospheres In-Situ Grown on Carbon Nanotubes: Anodes for NIBs and KIBs

by Meng Li, Fengbin Huang, Jin Pan, Luoyang Li, Yifan Zhang, Qingrong Yao, Huaiying Zhou and Jianqiu Deng

Nanomaterials 2019, 9(9), 1323; https://doi.org/10.3390/nano9091323 - 15 Sep 2019

Cited by 25 | Viewed by 3876

Abstract

Antimony sulfide (Sb₂S₃) with a high theoretical capacity is considered as a promising candidate for Na-ion batteries (NIBs) and K-ion batteries (KIBs). However, its poor electrochemical activity and structural stability are the main issues to be solved. Herein, amorphous [...] Read more.

Antimony sulfide (Sb₂S₃) with a high theoretical capacity is considered as a promising candidate for Na-ion batteries (NIBs) and K-ion batteries (KIBs). However, its poor electrochemical activity and structural stability are the main issues to be solved. Herein, amorphous Sb₂S₃ nanospheres/carbon nanotube (Sb₂S₃/CNT) nanocomposites are successfully synthesized via one step self-assembly method. In-situ growth of amorphous Sb₂S₃ nanospheres on the CNTs is confirmed by X-ray diffraction, field-emission scanning electron microscopy, and transmission electron microscopy. The amorphous Sb₂S₃/CNT nanocomposites as an anode for NIBs exhibit excellent electrochemical performance, delivering a high charge capacity of 870 mA h g⁻¹ at 100 mA g⁻¹, with an initial coulomb efficiency of 77.8%. Even at 3000 mA g⁻¹, a charge capacity of 474 mA h g⁻¹ can be achieved. As an anode for KIBs, the amorphous Sb₂S₃/CNT nanocomposites also demonstrate a high charge capacity of 451 mA h g⁻¹ at 25 mA g⁻¹. The remarkable performance of the amorphous Sb₂S₃/CNT nanocomposites is attributed to the synergic effects of the amorphous Sb₂S₃ nanospheres and 3D porous conductive network constructed by the CNTs. Full article

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XRD patterns of the as-prepared Sb2S3/carbon nanotube (CNT) nanocomposites, pure Sb2S3 and CNTs. Full article ">Figure 2
SEM and TEM images of the as-synthesized Sb2S3/CNT nanocomposites. (a,b) SEM images, (c,d) TEM images and (e) EDX spectrum. Selected-area electron diffraction (SAED) pattern is illustrated in (d). Full article ">Figure 2 Cont.
SEM and TEM images of the as-synthesized Sb2S3/CNT nanocomposites. (a,b) SEM images, (c,d) TEM images and (e) EDX spectrum. Selected-area electron diffraction (SAED) pattern is illustrated in (d). Full article ">Figure 3
Electrochemical properties of the Sb2S3/CNT anode for Na-ion batteries (NIBs) in a voltage range of 0.01–1.5 V. (a) Cyclic voltammetry (CV) curves, (b) galvanostatic discharge-charge profiles measured under a current density of 100 mA g−1, (c) cycling performance at 100 mA g−1 and (d) rate capability. Full article ">Figure 4
Electrochemical performance of the Sb2S3/CNT anode for K-ion batteries (KIBs). (a) CV curves, (b) the galvanostatic discharge-charge curves at various current densities, (c) rate capability and (d) cycling performance at 500 mA g−1. Full article ">

10 pages, 3519 KiB

Open AccessArticle

A Highly Efficient and Durable Fluorescent Paper Produced from Bacterial Cellulose/Eu Complex and Cellulosic Fibers

by Mingquan Zhang, Xiao Wu, Zhenhua Hu, Zhouyang Xiang, Tao Song and Fachuang Lu

Nanomaterials 2019, 9(9), 1322; https://doi.org/10.3390/nano9091322 - 15 Sep 2019

Cited by 13 | Viewed by 4061

Abstract

The general method of producing fluorescent paper by coating fluorescent substances onto paper base faces the problems of low efficiency and poor durability. Bacterial cellulose (BC) with its nanoporous structure can be used to stabilize fluorescent particles. In this study, we used a [...] Read more.

The general method of producing fluorescent paper by coating fluorescent substances onto paper base faces the problems of low efficiency and poor durability. Bacterial cellulose (BC) with its nanoporous structure can be used to stabilize fluorescent particles. In this study, we used a novel method to produce fluorescent paper by first making Eu/BC complex and then processing the complex and cellulosic fibers into composite paper sheets. For this composting method, BC can form very stable BC/Eu complex due to its nanoporous structure, while the plant-based cellulosic fibers reduce the cost and provide stiffness to the materials. The fluorescent paper demonstrated a great fluorescent property and efficiency. The ultraviolet absorbance or the fluorescent intensity of the Eu-BC fluorescent paper increased with the increase of Eu-BC content but remained little changed after Eu-BC content was higher than 5%. After folding 200 times, the fluorescence intensity of fluorescent paper decreased by only 0.7%, which suggested that the Eu-BC fluorescent paper has great stability and durability. Full article

(This article belongs to the Special Issue Nanocelluloses: Synthesis, Modification and Applications)

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SEM images of (a) unmodified BC, (b) Eu-BC, (c) paper sheet made from sugarcane bagasse pulp, (d) Eu-BC fluorescent paper, and the cellulosic fibers on Eu-BC fluorescent paper at (e) 2K× magnification and at (f) 5K× magnification. Full article ">Figure 2
XPS spectra of (a) Eu-BC and (b) 20% Eu-BC fluorescent paper. Full article ">Figure 3
Photographs of 20% BC paper (without Eu) and 20% Eu-BC fluorescent paper (a) under visible light and (b) under ultraviolet light. Full article ">Figure 4
(a) Fluorescence excitation spectra of Eu-BC and (b) fluorescence emission spectra of fluorescent paper sheets with different Eu-BC contents. Full article ">Figure 5
(a) UV-Vis absorbance spectra of fluorescent paper sheets with different Eu-BC contents and (b) changes in UV-Vis spectra after fluorescent paper was folded 200 times. Full article ">Figure 6
SEM images of (a) 5% Eu-BC fluorescent paper and (b) 20% Eu-BC fluorescent paper at 10K× magnification. Full article ">Figure 7
Changes of fluorescence emission spectra at 618 nm for Eu-BC fluorescent paper after 200 foldings. Full article ">

15 pages, 6368 KiB

Open AccessArticle

Tuning the Supramolecular Structures of Metal-Free Porphyrin via Surfactant Assisted Self-Assembly to Enhance Photocatalytic Performance

by Jinrong Lu, Zihan Li, Weijia An, Li Liu and Wenquan Cui

Nanomaterials 2019, 9(9), 1321; https://doi.org/10.3390/nano9091321 - 15 Sep 2019

Cited by 22 | Viewed by 3735

Abstract

Metal-free porphyrin with good planarity is beneficial to π–π stack interactions, which promotes electron coupling and the separation and transfer of photogenerated carriers. It is necessary to develop metal-free porphyrin-based photocatalysts and exploit the photocatalytic mechanism. Herein, metal–free porphyrin (5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin, TCPP) was self-assembled [...] Read more.

Metal-free porphyrin with good planarity is beneficial to π–π stack interactions, which promotes electron coupling and the separation and transfer of photogenerated carriers. It is necessary to develop metal-free porphyrin-based photocatalysts and exploit the photocatalytic mechanism. Herein, metal–free porphyrin (5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin, TCPP) was self-assembled through an acid-based neutralization reaction and mixing dual-solvents under surfactants to form different aggregates. Morphology structures, optical and optoelectronic properties of the TCPP aggregates were characterized in detail. TCPP self-assemblies showed higher photocatalytic activities for the degradation of phenol under visible light than untreated TCPP powders, and the aggregates of nanorods formed through the acid-based neutralization reaction in the presence of hexadecyl trimethyl ammonium bromide (CTAB) possessed 2.6 times more activity than the nanofiber aggregates formed through mixing dual-solvents. It was proved that self-assembly methods are crucial for controlling the aggregation of porphyrins to form different aggregations, which have a profound impact on the photocatalytic activity. Full article

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11 pages, 4997 KiB

Open AccessArticle

Graphene−Perfluoroalkoxy Nanocomposite with High Through-Plane Thermal Conductivity Fabricated by Hot-Pressing

by Xinru Zhang, Xiaoyu Xie, Xinzhi Cai, Zeyi Jiang, Ting Gao, Yujie Ren, Jian Hu and Xinxin Zhang

Nanomaterials 2019, 9(9), 1320; https://doi.org/10.3390/nano9091320 - 15 Sep 2019

Cited by 10 | Viewed by 3406

Abstract

With the rapid development of electronics and portable devices, polymer nanocomposites with high through-plane thermal conductivity (TC) are urgently needed. In this work, we fabricated graphene nanosheets−perfluoroalkoxy (GNs−PFA) composite sheets with high through-plane TCs via hot-pressing followed by mechanical machining. When the GNs [...] Read more.

With the rapid development of electronics and portable devices, polymer nanocomposites with high through-plane thermal conductivity (TC) are urgently needed. In this work, we fabricated graphene nanosheets−perfluoroalkoxy (GNs−PFA) composite sheets with high through-plane TCs via hot-pressing followed by mechanical machining. When the GNs content exceeded 10 wt%, GNs were vertically aligned in the PFA matrix, and the through-plane TCs of nanocomposites were 10–15 times higher than their in-plane TCs. In particular, the composite with 30 wt% GNs exhibited a through-plane TC of 25.57 W/(m·K), which was 9700% higher than that of pure PFA. The composite with 30 wt% GNs was attached to the surface of a high-power light-emitting diode (LED) to assess its heat-dissipation capability. The composite with vertically aligned GNs lowered the LED surface temperature by approximately 16 °C compared with pure PFA. Our facile, low-cost method allows for the large-scale production of GNs–PFA nanocomposites with high through-plane TCs, which can be used in various thermal-management applications. Full article

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Schematic representation of the fabrication process for the perfluoroalkoxy (PFA) composite with vertically aligned graphene nanosheets (GNs). First, GNs were prepared by exfoliating the flaked graphite. Then, PFA powder was added into the GNs dispersion and mixed while removing the ethanol. Afterwards, the GNs–PFA slurry was dried in a vacuum oven to remove the residual ethanol. The obtained powder was placed in a mold and hot-pressed into the bulk sample. Finally, the bulk sample was cut, perpendicular to its top surface, into thin sheets. Full article ">Figure 2
(a) SEM image of pristine flaked graphite. (b–f) SEM image, Raman spectra, bright-field TEM image, AFM image, high-resolution TEM, respectively, of the GNs produced by exfoliating graphite. Inset in (f) is fast-Fourier transformation pattern of the GNs. Full article ">Figure 3
(a) Thermogravimetric analysis curves for pure PFA and GNs–PFA nanocomposites. (b) The relationship between the initial and residual GNs content obtained in the thermogravimetric analysis. (c) The heat resistance index (THRI) for pure PFA and the GNs–PFA nanocomposites. Full article ">Figure 4
SEM images of the fractured surfaces for pure PFA (a), and (b–f) GNs–PFA nanocomposites containing 5, 10, 15, 20, and 30 wt% GNs, respectively. Full article ">Figure 5
(a) Through-plane TCs (λ⊥) and in-plane TCs (λ∥) of the PFA composites with vertically aligned GNs. (b) Ratio of through-plane TC to in-plane TC (i.e., λ⊥/λ∥). (c) Comparison of the through-plane TC of the composite sheet with 30 wt% GNs with the TC values of the GNs-based composites reported in literature. Full article ">Figure 6
Infrared thermal images (a) and surface temperatures (b) as a function of time for high-power LEDs attached to pure PFA and the PFA nanocomposites with 30 wt% GNs (in-plane TC: Layer aligned GNs; through-plane TC: Vertically aligned GNs). In the experiment, the back surface of a high-power LED lamp was attached to a thin composite sheet, then a heat sink was connected to the bottom side of the composite as shown by the insets in (a). Full article ">Figure 7
(a) Dimensional change of the samples as a function of temperature. (b) The determined CTE of nanocomposites. Full article ">

13 pages, 1424 KiB

Open AccessArticle

Sustainable Desalination by 3:1 Reduced Graphene Oxide/Titanium Dioxide Nanotubes (rGO/TiONTs) Composite via Capacitive Deionization at Different Sodium Chloride Concentrations

by John Paolo L. Lazarte, Liza Bautista-Patacsil, Ramon Christian P. Eusebio, Aileen H. Orbecido and Ruey-an Doong

Nanomaterials 2019, 9(9), 1319; https://doi.org/10.3390/nano9091319 - 15 Sep 2019

Cited by 8 | Viewed by 3507

Abstract

The capability of novel 3:1 reduced graphene oxide/titanium dioxide nanotubes (rGO/TiONTs) composite to desalinate using capacitive deionization (CDI) employing highly concentrated NaCl solutions was tested in this study. Parameters such as material wettability, electrosorption capacity, charge efficiency, energy consumption, and charge-discharge retention were [...] Read more.

The capability of novel 3:1 reduced graphene oxide/titanium dioxide nanotubes (rGO/TiONTs) composite to desalinate using capacitive deionization (CDI) employing highly concentrated NaCl solutions was tested in this study. Parameters such as material wettability, electrosorption capacity, charge efficiency, energy consumption, and charge-discharge retention were tested at different NaCl initial concentrations—100 ppm, 2000 ppm, 15,000 ppm, and 30,000 ppm. The rGO/TiONTs composite showed good material wettability before and after CDI runs with its contact angles equal to 52.11° and 56.07°, respectively. Its two-hour electrosorption capacity during CDI at 30,000 ppm NaCl influent increased 1.34-fold compared to 100 ppm initial NaCl influent with energy consumption constant at 1.11 kWh per kg with NaCl removed. However, the percentage discharge (concentration-independent) at zero-voltage ranged from 4.9–7.27% only after 30 min of desorption. Repeated charge/discharge at different amperes showed that the slowest charging rate of 0.1 A·g⁻¹ had the highest charging time retention at 60% after 100 cycles. Increased concentration likewise increases charging time retention. With this consistent performance of a CDI system utilizing rGO/TiONTs composite, even at 30,000 ppm and 100 cycles, it can be a sustainable alternative desalination technology, especially if a low charging current with reverse voltage discharge is set for a longer operation. Full article

(This article belongs to the Special Issue Synthesis and Applications of Graphite Oxide and Graphene Oxide Nanocomposites)

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Magnified digital images of electrodes after operation at (A) 100 ppm, (B) 2000 ppm, (C) 15,000 ppm, (D) 30,000 ppm, showing an intact arrangement on the titanium current collector plate. No significant accumulation of sodium crystals on the surface were found. Magnification: 50×. Full article ">Figure 2
Chronoamperometric plot of CDI at different sodium chloride concentrations showing a consistent current behavior at all concentrations tested. The initial peak observed at the start of each of the operations is due to sudden introduction of 1.2 V to the system while the sudden drop towards the end of the reaction is fue to the removal of this voltage by the instrument, BioLogic SP-150. Full article ">Figure 3
Charge accumulation plot at different concentrations of sodium chloride showing a consistent trend throughout the electrosorption and desorption stage. Rate of specific charge accumulation increases with concentration as shown by the slope. The initial specific charge accumulated, however, does not correlate to the initial concentration but due to uncontrollable factors caused by the instrument and set-up. Full article ">Figure 4
Charging time (capacity) conservation plot at different sodium chloride concentrations showing that retention increases with increasing concentration. Lower specific charging current leads to a higher retention due to more rigorous and thorough ion removal during discharge. Full article ">Figure 5
Chronocoulometric plot at different sodium chloride concentrations set at five different charging currents repeated five times per set, showing that the electrodes were not completely discharged every end of the cycle, leading to a net accumulation of charge as the cycle is repeated each set. Full article ">Figure 6
Charge time (capacity) conservation plot at different charging currents showing that retention increases with specific current. All plots approach a lower limit of charging time retention with increasing number of cycles, implying that the electrode can be recycled for at least 100 cycles. Full article ">

12 pages, 3601 KiB

Open AccessArticle

Zinc Oxide Nanoparticles Cytotoxicity and Release from Newly Formed PMMA–ZnO Nanocomposites Designed for Denture Bases

by Mariusz Cierech, Jacek Wojnarowicz, Adam Kolenda, Agata Krawczyk-Balska, Emilia Prochwicz, Bartosz Woźniak, Witold Łojkowski and Elżbieta Mierzwińska-Nastalska

Nanomaterials 2019, 9(9), 1318; https://doi.org/10.3390/nano9091318 - 15 Sep 2019

Cited by 62 | Viewed by 5539

Abstract

The goal of the study was to investigate the level of zinc oxide nanoparticles (ZnO NPs) release from polymethyl methacrylate (PMMA)–ZnO nanocomposites (2.5%, 5%, and 7.5% w/w), as well as from the ZnO NPs layer produced on pure PMMA, and [...] Read more.

The goal of the study was to investigate the level of zinc oxide nanoparticles (ZnO NPs) release from polymethyl methacrylate (PMMA)–ZnO nanocomposites (2.5%, 5%, and 7.5% w/w), as well as from the ZnO NPs layer produced on pure PMMA, and the impact of the achieved final ZnO NPs concentration on cytotoxicity, before the potential use as an alternative material for denture bases. The concentration of ZnO nanoparticles released to the aqueous solution of Zn²⁺ ions was assessed using optical emission spectrometry with inductively coupled plasma (ICP-OES). In the control group (pure PMMA), the released mean for ZnO was 0.074 mg/L and for individual nanocomposites at concentrations of 2.5%, 5%, and 7.5% was 2.281 mg/L, 2.143 mg/L, and 3.512 mg/L, respectively. The median for the ZnO NPs layer produced on PMMA was 4.878 mg/L. In addition, in vitro cytotoxicity of ZnO NPs against the human HeLa cell line was determined through the reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) dye. The cytotoxicity studies demonstrate that ZnO nanoparticles in the concentrations up to 20 mg/L have no adverse effect on HeLa cells. When compared with the released and cytotoxic concentrations of ZnO NPs, it can be expected that ZnO released from dental prostheses to the oral cavity environment will have no cytotoxic effect on host cells. Full article

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

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10 pages, 3160 KiB

Open AccessCommunication

A Portable Electrospinner for Nanofiber Synthesis and Its Application for Cosmetic Treatment of Alopecia

by Richard A. Revia, Brandon A. Wagner and Miqin Zhang

Nanomaterials 2019, 9(9), 1317; https://doi.org/10.3390/nano9091317 - 14 Sep 2019

Cited by 25 | Viewed by 3617

Abstract

A portable, handheld electrospinning apparatus is designed and constructed using off-the-shelf components and 3D-printed parts. The portable electrospinner is used to generate nanofibers with diameters ranging from 85 to 600 nm; examination of these fibers is achieved with scanning electron microscopy. This portable [...] Read more.

A portable, handheld electrospinning apparatus is designed and constructed using off-the-shelf components and 3D-printed parts. The portable electrospinner is used to generate nanofibers with diameters ranging from 85 to 600 nm; examination of these fibers is achieved with scanning electron microscopy. This portable electrospinner has similar capabilities to standard stationary benchtop electrospinners in terms of the diversity of polymers the device is able to spin into nanofibers and their resulting size and morphology. However, it provides much more ambulatory flexibility, employs current-limiting measures that allow for safer operation and is cost effective. As a demonstration of the device’s unique application space afforded by its portability, the device is applied in direct-to-skin electrospinning to improve the aesthetics of simulated hair loss in a mouse model by electrospinning dyed polyacrylonitrile nanofibers that mimic hair. The superficial nanofiber treatment for thinning hair is able to achieve an improvement in appearance similar to that of a commercially available powder product but outperforms the powder in the nanofiber’s superior adherence to the affected area. The portable electrospinning apparatus overcomes many limitations of immobile benchtop electrospinners and holds promise for applications in consumer end-use scenarios such as the treatment of alopecia via cosmetic hair thickening. Full article

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Graphical abstract

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Full article ">Figure 1
Handheld electrospinner device. (a) Main PCB with two HV DC-DC converters: positive (left) and negative (right). (b) Syringe pump driven by a stepper motor. (c) Front panel user interface. Fully constructed handheld electrospinning apparatus with (d) the handle detached and (e) the handle attached. Full article ">Figure 2
An array of nanofibers synthesized with the portable electrospinner: (a) 4 wt.% CA in acetone/water, (b) 6 wt.% PVA in THF, (c) 10 wt.% PAN in DMF, (d) 6 wt.% PEO in water, (e) 15 wt.% PCL in TFE and (f) 15 wt.% PVDF in DMF/acetone. Insets show SEM images of higher magnification. Full article ">Figure 3
Array of nanofibers synthesized with a conventional benchtop electrospinner: (a) 4 wt.% CA in acetone/water, (b) 6 wt.% PVA in THF, (c) 10 wt.% PAN in DMF, (d) 6 wt.% PEO in water, (e) 15 wt.% PCL in TFE and (f) 15 wt.% PVDF in DMF/acetone. Full article ">Figure 4
Beads electrosprayed from (a) 12 wt.% PS in THF and (b) 5 wt.% PVP in ethanol. Full article ">Figure 5
Application of the portable electrospinner for hair thickening. (a) A black-haired mouse with a small patch of hair removed. (b) Hair-thickening with black-dyed, electrospun PAN nanofibers. (c) Hair-thickening with a commercial powder product (Toppik™). (d) SEM image of the dyed PAN nanofibers. (e) Virtually no residue is left after contacting the nanofiber-treated skin to a napkin. (f) Significant residue left after contacting the Toppik™-treated skin to a napkin. Full article ">

20 pages, 5213 KiB

Open AccessArticle

Exploring the Effect of the Irradiation Time on Photosensitized Dendrimer-Based Nanoaggregates for Potential Applications in Light-Driven Water Photoreduction

by Natalia P. Martínez, Ricardo Inostroza-Rivera, Boris Durán, Leonard Molero, Sebastián Bonardd, Oscar Ramírez, Mauricio Isaacs, David Díaz Díaz, Angel Leiva and César Saldías

Nanomaterials 2019, 9(9), 1316; https://doi.org/10.3390/nano9091316 - 14 Sep 2019

Cited by 5 | Viewed by 2632

Abstract

Fourth generation polyamidoamine dendrimer (PAMAM, G4) modified with fluorescein units (F) at the periphery and Pt nanoparticles stabilized by L-ascorbate were prepared. These dendrimers modified with hydrophobic fluorescein were used to achieve self-assembling structures, giving rise to the formation of nanoaggregates in water. [...] Read more.

Fourth generation polyamidoamine dendrimer (PAMAM, G4) modified with fluorescein units (F) at the periphery and Pt nanoparticles stabilized by L-ascorbate were prepared. These dendrimers modified with hydrophobic fluorescein were used to achieve self-assembling structures, giving rise to the formation of nanoaggregates in water. The photoactive fluorescein units were mainly used as photosensitizer units in the process of the catalytic photoreduction of water propitiated by light. Complementarily, Pt-ascorbate nanoparticles acted as the active sites to generate H₂. Importantly, the study of the functional, optical, surface potential and morphological properties of the photosensitized dendrimer aggregates at different irradiation times allowed for insights to be gained into the behavior of these systems. Thus, the resultant photosensitized PAMAM-fluorescein (G4-F) nanoaggregates (NG) were conveniently applied to light-driven water photoreduction along with sodium L-ascorbate and methyl viologen as the sacrificial reagent and electron relay agent, respectively. Notably, these aggregates exhibited appropriate stability and catalytic activity over time for hydrogen production. Additionally, in order to propose a potential use of these types of systems, the in situ generated H₂ was able to reduce a certain amount of methylene blue (MB). Finally, theoretical electronic analyses provided insights into the possible excited states of the fluorescein molecules that could intervene in the global mechanism of H₂ generation. Full article

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Nanomaterials, Volume 9, Issue 9 (September 2019) – 162 articles

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