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Nanomaterials, Volume 7, Issue 9 (September 2017)

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Cover Story We have exploited the self-assembly of polystyrene nanospheres to provide a template for producing [...] Read more.
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Open AccessArticle Bi-Component Nanostructured Arrays of Co Dots Embedded in Ni80Fe20 Antidot Matrix: Synthesis by Self-Assembling of Polystyrene Nanospheres and Magnetic Properties
Nanomaterials 2017, 7(9), 232; doi:10.3390/nano7090232
Received: 28 July 2017 / Revised: 17 August 2017 / Accepted: 19 August 2017 / Published: 23 August 2017
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Abstract
A bi-component nanostructured system composed by a Co dot array embedded in a Ni80Fe20 antidot matrix has been prepared by means of the self-assembling polystyrene nanospheres lithography technique. Reference samples constituted by the sole Co dots or Ni80Fe
[...] Read more.
A bi-component nanostructured system composed by a Co dot array embedded in a Ni80Fe20 antidot matrix has been prepared by means of the self-assembling polystyrene nanospheres lithography technique. Reference samples constituted by the sole Co dots or Ni80Fe20 antidots have also been prepared, in order to compare their properties with those of the bi-component material. The coupling between the two ferromagnetic elements has been studied by means of magnetic and magneto-transport measurements. The Ni80Fe20 matrix turned out to affect the vortex nucleation field of the Co dots, which in turn modifies the magneto-resistance behaviour of the system and its spinwave properties. Full article
(This article belongs to the Special Issue Multifunctional Metallic Nanomaterials)
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Open AccessArticle Highly Efficient and Stable Organic Solar Cells via Interface Engineering with a Nanostructured ITR-GO/PFN Bilayer Cathode Interlayer
Nanomaterials 2017, 7(9), 233; doi:10.3390/nano7090233
Received: 22 July 2017 / Revised: 10 August 2017 / Accepted: 21 August 2017 / Published: 23 August 2017
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Abstract
An innovative bilayer cathode interlayer (CIL) with a nanostructure consisting of in situ thermal reduced graphene oxide (ITR-GO) and poly[(9,9-bis(3′-(N,N-dimethylamion)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctyl) fluorene] (PFN) has been fabricated for inverted organic solar cells (OSCs). An approach to prepare a CIL of high
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An innovative bilayer cathode interlayer (CIL) with a nanostructure consisting of in situ thermal reduced graphene oxide (ITR-GO) and poly[(9,9-bis(3′-(N,N-dimethylamion)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctyl) fluorene] (PFN) has been fabricated for inverted organic solar cells (OSCs). An approach to prepare a CIL of high electronic quality by using ITR-GO as a template to modulate the morphology of the interface between the active layer and electrode and to further reduce the work function of the electrode has also been realized. This bilayer ITR-GO/PFN CIL is processed by a spray-coating method with facile in situ thermal reduction. Meanwhile, the CIL shows a good charge transport efficiency and less charge recombination, which leads to a significant enhancement of the power conversion efficiency from 6.47% to 8.34% for Poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl} (PTB7):[6,6]-phenyl-C71-butyric acid methyl ester (PC71BM)-based OSCs. In addition, the long-term stability of the OSC is improved by using the ITR-GO/PFN CIL when compared with the pristine device. These results indicate that the bilayer ITR-GO/PFN CIL is a promising way to realize high-efficiency and stable OSCs by using water-soluble conjugated polymer electrolytes such as PFN. Full article
(This article belongs to the Special Issue Nanomaterials for Renewable and Sustainable Energy)
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Open AccessArticle Preparation and Structural Analysis of Nano-Silver Loaded Poly(styrene-co-acrylic acid) Core-Shell Nanospheres with Defined Shape and Composition
Nanomaterials 2017, 7(9), 234; doi:10.3390/nano7090234
Received: 30 June 2017 / Revised: 16 August 2017 / Accepted: 18 August 2017 / Published: 23 August 2017
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Abstract
A systematic study for the preparation and structural analysis of poly(styrene-co-acrylic acid) composite nanospheres (PSA) and silver nanoparticles loaded poly(styrene-co-acrylic acid) composite nanospheres (nAg@PSA) is reported. Poly(styrene-co-acrylic acid) nanospheres were synthesized by soap-free emulsion polymerization of styrene
[...] Read more.
A systematic study for the preparation and structural analysis of poly(styrene-co-acrylic acid) composite nanospheres (PSA) and silver nanoparticles loaded poly(styrene-co-acrylic acid) composite nanospheres (nAg@PSA) is reported. Poly(styrene-co-acrylic acid) nanospheres were synthesized by soap-free emulsion polymerization of styrene (St) and acrylic acid (AA) in water. Ag nanoparticles (Ag-NPs) were well-dispersed on the surfaces of poly(styrene-co-acrylic acid) composite nanospheres by in situ chemical reduction of AgNO3 using NaBH4 as a reducing agent in water. The particle size of PSA nanospheres was uniform. The surfaces of PSA nanospheres were distributed by highly uniform half-sphere arrays. Those half-sphere protruded more with the increase of the feeding amount of AA or the feed ratios of AA and St. The carboxyl groups content of nanospheres was directly proportional to the nanosphere surface area. This relationship and X-ray photoelectron spectroscopy and transmission electron microscopy images of the PSA nanospheres indicate that the acrylic acid was mainly distributed on the surface of the polystyrene spheres with unnegligible thickness. The number of Ag-NPs depends on immobilized carboxyl groups on the surface of PSA, according to thermogravimetry, ultraviolet-visible, X-ray diffraction and transmission electron microscopy results. Full article
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Open AccessArticle Radiolytic Synthesis of Pt-Particle/ABS Catalysts for H2O2 Decomposition in Contact Lens Cleaning
Nanomaterials 2017, 7(9), 235; doi:10.3390/nano7090235
Received: 29 June 2017 / Accepted: 21 August 2017 / Published: 23 August 2017
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Abstract
A container used in contact lens cleaning requires a Pt plating weight of 1.5 mg for H2O2 decomposition although Pt is an expensive material. Techniques that decrease the amount of Pt are therefore needed. In this study, Pt nanoparticles instead
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A container used in contact lens cleaning requires a Pt plating weight of 1.5 mg for H2O2 decomposition although Pt is an expensive material. Techniques that decrease the amount of Pt are therefore needed. In this study, Pt nanoparticles instead of Pt plating film were supported on a substrate of acrylonitrile–butadiene–styrene copolymer (ABS). This was achieved by the reduction of Pt ions in an aqueous solution containing the ABS substrate using high-energy electron-beam irradiation. Pt nanoparticles supported on the ABS substrate (Pt-particle/ABS) had a size of 4–10 nm. The amount of Pt required for Pt-particle/ABS was 250 times less than that required for an ABS substrate covered with Pt plating film (Pt-film/ABS). The catalytic activity for H2O2 decomposition was estimated by measuring the residual H2O2 concentration after immersing the catalyst for 360 min. The Pt-particle/ABS catalyst had a considerably higher specific catalytic activity for H2O2 decomposition than the Pt-film/ABS catalyst. In addition, sterilization performance was estimated from the initial rate of H2O2 decomposition over 60 min. The Pt-particle/ABS catalyst demonstrated a better sterilization performance than the Pt-film/ABS catalyst. The difference between Pt-particle/ABS and Pt-film/ABS was shown to reflect the size of the O2 bubbles formed during H2O2 decomposition. Full article
(This article belongs to the Special Issue Noble Metal Nanoparticles in Catalysis)
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Open AccessArticle Electrostatic Assembly of Platinum Nanoparticles along Electrospun Polymeric Nanofibers for High Performance Electrochemical Sensors
Nanomaterials 2017, 7(9), 236; doi:10.3390/nano7090236
Received: 9 July 2017 / Revised: 14 August 2017 / Accepted: 15 August 2017 / Published: 24 August 2017
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Abstract
A novel polyacrylonitrile (PAN) nanofibrous membrane conjugated with platinum nanoparticles (PtNPs) was fabricated by electrospinning and electrostatic assembly techniques. In this procedure, PAN was electrospun with 3-aminopropyltriethoxysilane (APS) together as precursor materials. First, amine groups were introduced onto PAN nanofibers, and then the
[...] Read more.
A novel polyacrylonitrile (PAN) nanofibrous membrane conjugated with platinum nanoparticles (PtNPs) was fabricated by electrospinning and electrostatic assembly techniques. In this procedure, PAN was electrospun with 3-aminopropyltriethoxysilane (APS) together as precursor materials. First, amine groups were introduced onto PAN nanofibers, and then the as-prepared negative-charged platinum nanoparticles (PtNPs) were conjugated onto the surface of the amino-modified PAN nanofibers uniformly by the electrostatic interaction-mediated assembly. The fabricated PAN–PtNPs hybrid nanofibrous membrane was further utilized to modify the glassy carbon electrodes and was used for the fabrication of a non-enzymatic amperometric sensor to detect hydrogen peroxide (H2O2). The electrochemical results indicated that, due to the uniform dispersion of PtNPs and the electrostatic interaction between amine groups and PtNPs, the fabricated PAN–PtNPs nanofibrous membrane-based electrochemical sensor showed excellent electrocatalytic activity toward H2O2, and the chronoamperometry measurements illustrated that the fabricated sensor had a high sensitivity for detecting H2O2. It is anticipated that the strategies used in this work will not only guide the design and fabrication of functional polymeric nanofiber-based biomaterials and nanodevices, but also extend their potential applications in energy storage, cytology, and tissue engineering. Full article
(This article belongs to the Special Issue The Fabrication and Application of Nanofibers)
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Open AccessArticle Fabrication of Monodisperse Flower-Like Coordination Polymers (CP) Microparticles by Spray Technique
Nanomaterials 2017, 7(9), 237; doi:10.3390/nano7090237
Received: 4 July 2017 / Revised: 19 August 2017 / Accepted: 21 August 2017 / Published: 25 August 2017
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Abstract
In this manuscript, we have developed an efficient spraying method to successfully fabricate a series of flower-like coordination polymers (CP) microparticles, including Co/BDC (1,4-benzenedicarboxylate) metal organic frameworks (MOF) and infinite coordination polymers (ICP) microparticles, as well as Ni-Co/BDC MOF and Zn/DOBDC (2,5-dioxido-1,4-benzenedicarboxylate) MOF.
[...] Read more.
In this manuscript, we have developed an efficient spraying method to successfully fabricate a series of flower-like coordination polymers (CP) microparticles, including Co/BDC (1,4-benzenedicarboxylate) metal organic frameworks (MOF) and infinite coordination polymers (ICP) microparticles, as well as Ni-Co/BDC MOF and Zn/DOBDC (2,5-dioxido-1,4-benzenedicarboxylate) MOF. The spraying method has shown high efficiency and universality in synthesizing the flower-like CP. The crystalline structure can be adjusted by varying the solvent composition in the spraying process. SEM observation demonstrated the MOF and ICP microparticles possess the similar flower-like structure, which is composed of nanoflakes with smooth surface, and the flower-like microparticles could be monodisperse with as low as 5% polydispersity. Moreover, the fabrication of the flower-like CP microparticles by spraying has a wide operation window, because there is no need to precisely control the experiment conditions, like solvents, concentration, and spray order. Due to the practicality of spray technique, this work would pave the way for the manufacture of the flower-like materials and have great potential in applications of catalysis, sensor, energy storage, and so on. Full article
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Open AccessArticle Optimization of the Fano Resonance Lineshape Based on Graphene Plasmonic Hexamer in Mid-Infrared Frequencies
Nanomaterials 2017, 7(9), 238; doi:10.3390/nano7090238
Received: 25 July 2017 / Revised: 18 August 2017 / Accepted: 22 August 2017 / Published: 26 August 2017
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Abstract
In this article, the lineshape of Fano-like resonance of graphene plasmonic oligomers is investigated as a function of the parameters of the nanostructures, such as disk size, chemical potential and electron momentum relaxation time in mid-infrared frequencies. Also, the mechanism of the optimization
[...] Read more.
In this article, the lineshape of Fano-like resonance of graphene plasmonic oligomers is investigated as a function of the parameters of the nanostructures, such as disk size, chemical potential and electron momentum relaxation time in mid-infrared frequencies. Also, the mechanism of the optimization is discussed. Furthermore, the environmental index sensing effect of the proposed structure is revealed, and a figure of merit of 25.58 is achieved with the optimized graphene oligomer. The proposed nanostructure could find applications in the fields of chemical or biochemical sensing. Full article
(This article belongs to the Special Issue Graphene and Nanotube Based Devices)
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Open AccessArticle Synthesis of Au-Pd Bimetallic Nanoflowers for Catalytic Reduction of 4-Nitrophenol
Nanomaterials 2017, 7(9), 239; doi:10.3390/nano7090239
Received: 19 July 2017 / Revised: 6 August 2017 / Accepted: 22 August 2017 / Published: 26 August 2017
Cited by 1 | PDF Full-text (3391 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Due to the great potential to improve catalytic performance, gold (Au) and palladium (Pd) bimetallic catalysts have prompted structure-controlled synthesis of Au-Pd nanoalloys bounded by high-index facets. In this work, we prepared Au-Pd bimetallic nanoflowers (NFs) with a uniform size, well-defined dendritic morphology,
[...] Read more.
Due to the great potential to improve catalytic performance, gold (Au) and palladium (Pd) bimetallic catalysts have prompted structure-controlled synthesis of Au-Pd nanoalloys bounded by high-index facets. In this work, we prepared Au-Pd bimetallic nanoflowers (NFs) with a uniform size, well-defined dendritic morphology, and homogeneous alloy structure in an aqueous solution by seed-mediated synthesis. The prepared bimetallic NFs were fully characterized using a combination of transmission electron microscopy, Ultraviolet-Visible (UV-vis) spectroscopy, inductively coupled plasma optical emission spectroscopy, and cyclic voltammetry measurements. The catalytic activities of the prepared Au-Pd nanoparticles for 4-nitrophenol reduction were also investigated, and the activities are in the order of Au@Pd NFs > Au-Pd NFs (Au1Pd1 core) > Au-Pd NFs (Au core), which could be related to the content and exposed different reactive surfaces of Pd in alloys. This result clearly demonstrates that the superior activities of Au-Pd alloy nanodendrites could be attributed to the synergy between Au and Pd in catalysts. Full article
(This article belongs to the Special Issue Noble Metal Nanoparticles in Catalysis)
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Open AccessArticle Antimicrobial Properties of Silver Cations Substituted to Faujasite Mineral
Nanomaterials 2017, 7(9), 240; doi:10.3390/nano7090240
Received: 10 July 2017 / Revised: 7 August 2017 / Accepted: 25 August 2017 / Published: 27 August 2017
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Abstract
A goal of our study was to find an alternative to nano-silver-based antimicrobial materials which would contain active silver immobilized in a solid matrix that prevents its migration into the surrounding environment. In this study, we investigated whether silver cations dispersed in an
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A goal of our study was to find an alternative to nano-silver-based antimicrobial materials which would contain active silver immobilized in a solid matrix that prevents its migration into the surrounding environment. In this study, we investigated whether silver cations dispersed in an atomic form and trapped in an ion-exchanged zeolite show comparable antimicrobial activity to silver nanoparticles (NPs). The biocidal active material was prepared from the sodium form of faujasite type zeolite in two steps: (1) exchange with silver cations, (2) removal of the external silver oxide NPs by elution with Na2EDTA solution. The modified biocidal zeolite was then added to paper pulp to obtain sheets. The zeolite paper samples and reference samples containing silver NPs were tested in terms of biocidal activity against an array of fungi and bacteria strains, including Escherichia coli, Serratia marcescens, Bacillus subtilis, Bacillus megaterium, Trichoderma viride, Chaetomium globosum, Aspergillus niger, Cladosporium cladosporioides, and Mortierella alpina. The paper with the modified faujasite additive showed higher or similar antibacterial and antifungal activities towards the majority of tested microbes in comparison with the silver NP-filled paper. A reverse effect was observed for the Mortierella alpina strain. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
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Open AccessArticle The Improvement of Skin Whitening of Phenylethyl Resorcinol by Nanostructured Lipid Carriers
Nanomaterials 2017, 7(9), 241; doi:10.3390/nano7090241
Received: 1 August 2017 / Revised: 18 August 2017 / Accepted: 23 August 2017 / Published: 28 August 2017
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Abstract
Phenylethyl resorcinol (4-(1-phenylethyl)1,3-benzenediol) (PR) is a new whitening agent that has been found to have the ability to inhibit tyrosinase activity. However, the application of PR is limited by photo instability and poor solubility. PR-loaded nanostructured lipid carriers (PR-NLCs) were prepared by the
[...] Read more.
Phenylethyl resorcinol (4-(1-phenylethyl)1,3-benzenediol) (PR) is a new whitening agent that has been found to have the ability to inhibit tyrosinase activity. However, the application of PR is limited by photo instability and poor solubility. PR-loaded nanostructured lipid carriers (PR-NLCs) were prepared by the hot-melted ultrasonic method. Glycerol monostearate and olive oil were selected as the solid lipid and liquid lipid for considering the solubility of PR in liquid lipid and partition coefficient of PR in solid lipid, respectively. The particle size and polydispersity index of PR-NLCs were 57.9 ± 1.3 nm and 0.24 ± 0.01, respectively. The encapsulation efficiency and loading capacity of PR-NLCs were 93.1 ± 4.2% and 8.5 ± 0.4%, respectively. The stability test demonstrated that the incorporation of PR into NLCs conferred excellent physicochemical stability and photo stability for at least three months at 4 °C in the dark and 25 °C under daylight. In vitro release of PR-NLCs revealed a sustained release pattern. Cellular tyrosinase assay showed that PR-NLCs could significantly inhibit tyrosinase activity in melanoma cells, suggesting that NLCs can be used as a biocompatible nanocarrier for the effective delivery of skin whitening agents. Full article
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Open AccessArticle The Tuning of Optical Properties of Nanoscale MOFs-Based Thin Film through Post-Modification
Nanomaterials 2017, 7(9), 242; doi:10.3390/nano7090242
Received: 22 July 2017 / Revised: 17 August 2017 / Accepted: 22 August 2017 / Published: 29 August 2017
Cited by 1 | PDF Full-text (4828 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Optical properties, which determine the application of optical devices in different fields, are the most significant properties of optical thin films. In recent years, Metal-organic framework (MOF)-based optical thin films have attracted increasing attention because of their novel optical properties and important potential
[...] Read more.
Optical properties, which determine the application of optical devices in different fields, are the most significant properties of optical thin films. In recent years, Metal-organic framework (MOF)-based optical thin films have attracted increasing attention because of their novel optical properties and important potential applications in optical and photoelectric devices, especially optical thin films with tunable optical properties. This study reports the first example of tuning the optical properties of a MOF-based optical thin film via post-modification. The MOF-based optical thin film was composed of NH2-MIL-53(Al) nanorods (NRs) (MIL: Materials from Institute Lavoisier), and was constructed via a spin-coating method. Three aldehydes with different lengths of carbon chains were chosen to modify the MOF optical thin film to tune their optical properties. After post-modification, the structural color of the NH2-MIL-53(Al) thin film showed an obvious change from purple to bluish violet and cyan. The reflection spectrum and the reflectivity also altered in different degrees. The effective refractive index (neff) of MOFs thin film can also be tuned from 1.292 to 1.424 at a wavelength of 750 nm. The success of tuning of the optical properties of MOFs thin films through post-modification will make MOFs optical thin films meet different needs of optical properties in various optical and optoelectronic devices. Full article
(This article belongs to the Special Issue Nanoparticles in Metal-Organic Frameworks)
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Open AccessArticle Gadolinium-Doped Gallic Acid-Zinc/Aluminium-Layered Double Hydroxide/Gold Theranostic Nanoparticles for a Bimodal Magnetic Resonance Imaging and Drug Delivery System
Nanomaterials 2017, 7(9), 244; doi:10.3390/nano7090244
Received: 16 July 2017 / Revised: 18 August 2017 / Accepted: 25 August 2017 / Published: 31 August 2017
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Abstract
We have developed gadolinium-based theranostic nanoparticles for co-delivery of drug and magnetic resonance imaging (MRI) contrast agent using Zn/Al-layered double hydroxide as the nanocarrier platform, a naturally occurring phenolic compound, gallic acid (GA) as therapeutic agent, and Gd(NO3)3 as diagnostic
[...] Read more.
We have developed gadolinium-based theranostic nanoparticles for co-delivery of drug and magnetic resonance imaging (MRI) contrast agent using Zn/Al-layered double hydroxide as the nanocarrier platform, a naturally occurring phenolic compound, gallic acid (GA) as therapeutic agent, and Gd(NO3)3 as diagnostic agent. Gold nanoparticles (AuNPs) were grown on the system to support the contrast for MRI imaging. The nanoparticles were characterized using techniques such as Hi-TEM, XRD, ICP-ES. Kinetic release study of the GA from the nanoparticles showed about 70% of GA was released over a period of 72 h. The in vitro cell viability test for the nanoparticles showed relatively low toxicity to human cell lines (3T3) and improved toxicity on cancerous cell lines (HepG2). A preliminary contrast property test of the nanoparticles, tested on a 3 Tesla MRI machine at various concentrations of GAGZAu and water (as a reference) indicates that the nanoparticles have a promising dual diagnostic and therapeutic features to further develop a better future for clinical remedy for cancer treatment. Full article
(This article belongs to the Special Issue Nanocolloids for Nanomedicine and Drug delivery)
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Open AccessArticle A General Route for Growing Metal Sulfides onto Graphene Oxide and Exfoliated Graphite Oxide
Nanomaterials 2017, 7(9), 245; doi:10.3390/nano7090245
Received: 15 July 2017 / Revised: 18 August 2017 / Accepted: 26 August 2017 / Published: 31 August 2017
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Abstract
Graphene-based materials are elective materials for a number of technologies due to their unique properties. Also, semiconductor nanocrystals have been extensively explored due to their size-dependent properties that make them useful for several applications. By coupling both types of materials, new applications are
[...] Read more.
Graphene-based materials are elective materials for a number of technologies due to their unique properties. Also, semiconductor nanocrystals have been extensively explored due to their size-dependent properties that make them useful for several applications. By coupling both types of materials, new applications are envisaged that explore the synergistic properties in such hybrid nanostructures. This research reports a general wet chemistry method to prepare graphene oxide (GO) sheets decorated with nanophases of semiconductor metal sulfides. This method allows the in situ growth of metal sulfides onto GO by using metal dialkyldithiocarbamate complexes as single-molecule precursors. In particular, the role of GO as heterogeneous substrate for the growth of semiconductor nanocrystals was investigated by using Raman spectroscopic and imaging methods. The method was further extended to other graphene-based materials, which are easily prepared in a larger scale, such as exfoliated graphite oxide (EGO). Full article
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Open AccessArticle Thermal Conductivity of a Nanoscale Yttrium Iron Garnet Thin-Film Prepared by the Sol-Gel Process
Nanomaterials 2017, 7(9), 247; doi:10.3390/nano7090247
Received: 23 July 2017 / Revised: 28 August 2017 / Accepted: 29 August 2017 / Published: 31 August 2017
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Abstract
The thermal conductivity of a nanoscale yttrium iron garnet (Y3Fe5O12, YIG) thin-film prepared by a sol-gel method was evaluated using the ultrafast pump-probe technique in the present study. The thermoreflectance change on the surface of a 250
[...] Read more.
The thermal conductivity of a nanoscale yttrium iron garnet (Y3Fe5O12, YIG) thin-film prepared by a sol-gel method was evaluated using the ultrafast pump-probe technique in the present study. The thermoreflectance change on the surface of a 250 nm thick YIG film, induced by the irradiation of femtosecond laser pulses, was measured, and curve fitting of a numerical solution for the transient heat conduction equation to the experimental data was performed using the finite difference method in order to extract the thermal property. Results show that the film’s thermal conductivity is 22–83% higher than the properties of bulk YIG materials prepared by different fabrication techniques, reflecting the microstructural characteristics and quality of the film. Full article
(This article belongs to the Special Issue Sol-Gel Preparation of Nanomaterials)
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Open AccessArticle Characterization and Discrimination of Gram-Positive Bacteria Using Raman Spectroscopy with the Aid of Principal Component Analysis
Nanomaterials 2017, 7(9), 248; doi:10.3390/nano7090248
Received: 14 July 2017 / Revised: 27 August 2017 / Accepted: 28 August 2017 / Published: 1 September 2017
Cited by 1 | PDF Full-text (3380 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Raman scattering and its particular effect, surface-enhanced Raman scattering (SERS), are whole-organism fingerprinting spectroscopic techniques that gain more and more popularity in bacterial detection. In this work, two relevant Gram-positive bacteria species, Lactobacillus casei (L. casei) and Listeria monocytogenes (L.
[...] Read more.
Raman scattering and its particular effect, surface-enhanced Raman scattering (SERS), are whole-organism fingerprinting spectroscopic techniques that gain more and more popularity in bacterial detection. In this work, two relevant Gram-positive bacteria species, Lactobacillus casei (L. casei) and Listeria monocytogenes (L. monocytogenes) were characterized based on their Raman and SERS spectral fingerprints. The SERS spectra were used to identify the biochemical structures of the bacterial cell wall. Two synthesis methods of the SERS-active nanomaterials were used and the recorded spectra were analyzed. L. casei and L. monocytogenes were successfully discriminated by applying Principal Component Analysis (PCA) to their specific spectral data. Full article
(This article belongs to the Special Issue Nanomaterials for SERS Applications)
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Open AccessArticle Catalytic Behavior of Chromium Oxide Supported on Nanocasting-Prepared Mesoporous Alumina in Dehydrogenation of Propane
Nanomaterials 2017, 7(9), 249; doi:10.3390/nano7090249
Received: 24 July 2017 / Revised: 23 August 2017 / Accepted: 28 August 2017 / Published: 1 September 2017
Cited by 1 | PDF Full-text (2303 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Mesoporous alumina with narrow pore size distribution centered in the range of 4.4–5.0 nm and with a specific surface area as high as 270 m2·g−1 was prepared via the nanocasting approach using a CMK-3 carbon replica as a hard template.
[...] Read more.
Mesoporous alumina with narrow pore size distribution centered in the range of 4.4–5.0 nm and with a specific surface area as high as 270 m2·g−1 was prepared via the nanocasting approach using a CMK-3 carbon replica as a hard template. Based on this support, a series of catalysts containing 1, 5, 10, 20 and 30 wt % of chromium was prepared by incipient wetness impregnation, characterized, and studied in the dehydrogenation of propane to propene (PDH). Cr species in three oxidation states—Cr(III), Cr(V) and Cr(VI)—were found on the oxidized surface of the catalysts. The concentration of these species varied with the total Cr loading. Temperature-programmed reduction (H2-TPR) and UV-Vis diffuse reflectance spectroscopy (UV-Vis-DRS) studies revealed that Cr(VI) species dominated at the lowest Cr content. An increase in the Cr loading resulted in an appearance of an increasing amount of Cr(III) oxide. UV-Vis-DRS measurements performed in situ during the PDH process showed that at the beginning of the catalytic test Cr(VI) species were reduced to Cr(III) redox species. A crucial role of the redox species in the PDH process over the catalysts with the low Cr content was confirmed. The stability test for the catalyst containing 20 wt % of Cr showed that this sample exhibited the reproducible catalytic performance after the first four regeneration–dehydrogenation cycles. Moreover, this catalyst had higher resistance on deactivation during the PDH process as compared to the reference catalyst with the same Cr loading, but was supported on commercially available alumina. Full article
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Open AccessArticle Dynamic Response of Graphitic Flakes in Nematic Liquid Crystals: Confinement and Host Effect
Nanomaterials 2017, 7(9), 250; doi:10.3390/nano7090250
Received: 22 July 2017 / Revised: 24 August 2017 / Accepted: 30 August 2017 / Published: 1 September 2017
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Abstract
Electric field-induced reorientation of suspended graphitic (GP) flakes and its relaxation back to the original state in a nematic liquid crystal (NLC) host are of interest not only in academia, but also in industrial applications, such as polarizer-free and optical film-free displays, and
[...] Read more.
Electric field-induced reorientation of suspended graphitic (GP) flakes and its relaxation back to the original state in a nematic liquid crystal (NLC) host are of interest not only in academia, but also in industrial applications, such as polarizer-free and optical film-free displays, and electro-optic light modulators. As the phenomenon has been demonstrated by thorough observation, the detailed study of the physical properties of the host NLC (the magnitude of dielectric anisotropy, elastic constants, and rotational viscosity), the size of the GP flakes, and cell thickness, are urgently required to be explored and investigated. Here, we demonstrate that the response time of GP flakes reorientation associated with an NLC host can be effectively enhanced by controlling the physical properties. In a vertical field-on state, higher dielectric anisotropy and higher elasticity of NLC give rise to quicker reorientation of the GP flakes (switching from planar to vertical alignment) due to the field-induced coupling effect of interfacial Maxwell-Wagner polarization and NLC reorientation. In a field off-state, lower rotational viscosity of NLC and lower cell thickness can help to reduce the decay time of GP flakes reoriented from vertical to planar alignment. This is mainly attributed to strong coupling between GP flakes and NLC originating from the strong π-π interaction between benzene rings in the honeycomb-like graphene structure and in NLC molecules. The high-uniformity of reoriented GP flakes exhibits a possibility of new light modulation with a relatively faster response time in the switching process and, thus, it can show potential application in field-induced memory and modulation devices. Full article
(This article belongs to the Special Issue Nanomaterials in Liquid Crystals)
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Open AccessArticle TiO2 Nanobelt@Co9S8 Composites as Promising Anode Materials for Lithium and Sodium Ion Batteries
Nanomaterials 2017, 7(9), 252; doi:10.3390/nano7090252
Received: 9 August 2017 / Revised: 26 August 2017 / Accepted: 28 August 2017 / Published: 2 September 2017
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Abstract
TiO2 anodes have attracted great attention due to their good cycling stability for lithium ion batteries and sodium ion batteries (LIBs and SIBs). Unfortunately, the low specific capacity and poor conductivity limit their practical application. The mixed phase TiO2 nanobelt (anatase
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TiO2 anodes have attracted great attention due to their good cycling stability for lithium ion batteries and sodium ion batteries (LIBs and SIBs). Unfortunately, the low specific capacity and poor conductivity limit their practical application. The mixed phase TiO2 nanobelt (anatase and TiO2-B) based Co9S8 composites have been synthesized via the solvothermal reaction and subsequent calcination. During the formation process of hierarchical composites, glucose between TiO2 nanobelts and Co9S8 serves as a linker to increase the nucleation and growth of sulfides on the surface of TiO2 nanobelts. As anode materials for LIBs and SIBs, the composites combine the advantages of TiO2 nanobelts with those of Co9S8 nanomaterials. The reversible specific capacity of TiO2 nanobelt@Co9S8 composites is up to 889 and 387 mAh·g−1 at 0.1 A·g−1 after 100 cycles, respectively. The cooperation of excellent cycling stability of TiO2 nanobelts and high capacities of Co9S8 nanoparticles leads to the good electrochemical performances of TiO2 nanobelt@Co9S8 composites. Full article
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Open AccessArticle Electrochemical Properties of an Na4Mn9O18-Reduced Graphene Oxide Composite Synthesized via Spray Drying for an Aqueous Sodium-Ion Battery
Nanomaterials 2017, 7(9), 253; doi:10.3390/nano7090253
Received: 17 August 2017 / Revised: 27 August 2017 / Accepted: 28 August 2017 / Published: 2 September 2017
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Abstract
An aqueous sodium ion battery (ASIB) with metal Zn as anode and Na4Mn9O18-reduced graphene oxide (Na4Mn9O18-RGO) as cathode has been developed. In this work, spherical Na4Mn9O18
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An aqueous sodium ion battery (ASIB) with metal Zn as anode and Na4Mn9O18-reduced graphene oxide (Na4Mn9O18-RGO) as cathode has been developed. In this work, spherical Na4Mn9O18-RGO composite particles were prepared via spray drying. The aqueous battery exhibits stable cyclability and high specific capacities. Typically, a high initial discharge capacity of 61.7 mAh·g−1 is attained at a high current rate of 4 C, and a stabilizing reversible capacity of 58.9 mAh·g−1 was obtained after 150 cycles. The network interlaced by RGO sheets provided fast electron conduction paths and structural stability to accommodate the mechanical stresses induced by sodium insertion and extraction, so the Na4Mn9O18-RGO electrode displayed superior electrochemical performance in the ASIB. Full article
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Open AccessArticle An Optimum Specimen Geometry for Equibiaxial Experimental Tests of Reinforced Magnetorheological Elastomers with Iron Micro- and Nanoparticles
Nanomaterials 2017, 7(9), 254; doi:10.3390/nano7090254
Received: 14 August 2017 / Revised: 29 August 2017 / Accepted: 31 August 2017 / Published: 3 September 2017
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Abstract
The aim of this paper focused on obtaining the optimum cruciform geometry of reinforced magnetorheological elastomers (MRE) to perform homogeneous equibiaxial deformation tests, by using optimization algorithms and Finite Element Method (FEM) simulations. To validate the proposed specimen geometry, a digital image correlation
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The aim of this paper focused on obtaining the optimum cruciform geometry of reinforced magnetorheological elastomers (MRE) to perform homogeneous equibiaxial deformation tests, by using optimization algorithms and Finite Element Method (FEM) simulations. To validate the proposed specimen geometry, a digital image correlation (DIC) system was used to compare experimental result measurements with respect to those of FEM simulations. Moreover, and based on the optimum cruciform geometry, specimens produced from MRE reinforced with carbonyl-iron microparticles or iron nanoparticles were subjected to equibiaxial loading and unloading cycles to examine their Mullin’s effect and their residual strain deformations. Full article
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Open AccessArticle Hollow Au–Ag Alloy Nanorices and Their Optical Properties
Nanomaterials 2017, 7(9), 255; doi:10.3390/nano7090255
Received: 26 July 2017 / Revised: 29 August 2017 / Accepted: 29 August 2017 / Published: 4 September 2017
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Abstract
Hollow noble metal nanoparticles have excellent performance not only in surface catalysis but also in optics. In this work, the hollow Au–Ag alloy nanorices are fabricated by the galvanic replacement reaction. The dark-field spectrum points out that there is a big difference in
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Hollow noble metal nanoparticles have excellent performance not only in surface catalysis but also in optics. In this work, the hollow Au–Ag alloy nanorices are fabricated by the galvanic replacement reaction. The dark-field spectrum points out that there is a big difference in the optical properties between the pure Ag nanorices and the hollow alloy nanorices that exhibit highly tunable localized surface plasmon resonances (LSPR) and that possess larger radiative damping, which is also indicated by the finite element method. Furthermore, the surface enhanced Raman scattering (SERS) and oxidation test indicate that hollow Au–Ag alloy nanorices show good anti-oxidation and have broad application prospects in surface-plasmon-related fields. Full article
(This article belongs to the Special Issue Nanomaterials for SERS Applications)
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Open AccessFeature PaperArticle Effects of a Transverse Field in Two Mixed-Spin Ising Bilayer Films
Nanomaterials 2017, 7(9), 256; doi:10.3390/nano7090256
Received: 16 June 2017 / Revised: 7 August 2017 / Accepted: 23 August 2017 / Published: 4 September 2017
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Abstract
The magnetic properties (phase diagrams and magnetizations) of two mixed-spin Ising bilayer films with a transverse field are investigated by the use of the effective field theory with correlations. The systems consist of two magnetic atoms where spin-1/2 atoms are directed to the
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The magnetic properties (phase diagrams and magnetizations) of two mixed-spin Ising bilayer films with a transverse field are investigated by the use of the effective field theory with correlations. The systems consist of two magnetic atoms where spin-1/2 atoms are directed to the z-direction and only spin-1 atoms are canted from the z-direction by applying a transverse field. We examined how magnetization sign reversal can be realized in the system, due to the effects of the transverse field on the spin-1 atoms. The compensation point phenomena are found in both systems, depending on the selections of physical parameters. However, the reentrant phenomena are found only for one of the two systems. Full article
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Open AccessArticle Effect of Different Activated Carbon as Carrier on the Photocatalytic Activity of Ag-N-ZnO Photocatalyst for Methyl Orange Degradation under Visible Light Irradiation
Nanomaterials 2017, 7(9), 258; doi:10.3390/nano7090258
Received: 1 August 2017 / Revised: 30 August 2017 / Accepted: 1 September 2017 / Published: 5 September 2017
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Abstract
In order to enhance the photodegradation of methyl orange (MO) by ZnO under visible light irradiation, ZnO nanoparticles co-doped with Ag and N and supported on activated carbon (AC) with different properties were synthesized through the sol-gel method. The prepared photocatalysts were characterized
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In order to enhance the photodegradation of methyl orange (MO) by ZnO under visible light irradiation, ZnO nanoparticles co-doped with Ag and N and supported on activated carbon (AC) with different properties were synthesized through the sol-gel method. The prepared photocatalysts were characterized in terms of the structure and properties through X-ray diffraction, N2 adsorption-desorption, ultraviolet-visible (UV-vis), diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, photoluminescence, and electron spin resonance. The photocatalytic activities of these photocatalysts followed the order: Ag-N-ZnO/ACs > Ag-N-ZnO > N, or Ag single-doped ZnO > commercial ZnO. This result was attributed to the small particle size, large surface area, narrow band gap, and high charge separation of Ag-N-ZnO/ACs. The Ag-N-ZnO/coconut husk activated carbon (Ag-N-ZnO/CHAC) exhibited the highest degradation efficiency of 98.82% for MO under visible light irradiation. This outcome was due to the abundant pore structure of Ag-N-ZnO/CHAC, resulting in stronger adsorption than that of other Ag-N-ZnO/ACs. Moreover, the degradation of MO on photocatalysis followed first order kinetics. The reactive species ·OH and ·O2 played more important roles in the photocatalytic degradation of MO over composite photocatalyst. Ag-N-ZnO/CHAC photocatalyst exhibited higher photocatalytic activity than unsupported Ag-N-ZnO after five recycling runs. Full article
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Open AccessArticle Hypophosphite/Graphitic Carbon Nitride Hybrids: Preparation and Flame-Retardant Application in Thermoplastic Polyurethane
Nanomaterials 2017, 7(9), 259; doi:10.3390/nano7090259
Received: 13 August 2017 / Revised: 29 August 2017 / Accepted: 30 August 2017 / Published: 5 September 2017
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Abstract
A series of aluminum hypophosphite (AHPi)/graphite-like carbon nitride (g-C3N4) (designated as CAHPi) hybrids were prepared, followed by incorporation into thermoplastic polyurethane (TPU). The introduction of CAHPi hybrids into TPU led to a marked reduction in the peak of the
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A series of aluminum hypophosphite (AHPi)/graphite-like carbon nitride (g-C3N4) (designated as CAHPi) hybrids were prepared, followed by incorporation into thermoplastic polyurethane (TPU). The introduction of CAHPi hybrids into TPU led to a marked reduction in the peak of the heat release rate (pHRR), total heat release, weight loss rate, smoke production rate and total smoke production (TSP). For instance, pHRR and TSP decreased by 40% and 50% for TPU/CAHPi20. Furthermore, the increasing fire growth index and decreasing fire performance index were obtained for TPU/CAHPi systems, suggesting reduced fire hazards. It was found that improved fire safety of TPU nanocomposites was contributed by condensed phase and gas phase mechanisms. On one hand, g-C3N4 accelerated the thermal decomposition of AHPi for the formation of more char layers. On the other hand, g-C3N4 induced AHPi to generate more free radical capture agents when exposed to flame, besides protecting AHPi against thermal oxidation. Full article
(This article belongs to the Special Issue Graphitic Carbon Nitride Nanostructures: Catalysis and Beyond)
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Open AccessArticle Biomass Waste Inspired Highly Porous Carbon for High Performance Lithium/Sulfur Batteries
Nanomaterials 2017, 7(9), 260; doi:10.3390/nano7090260
Received: 30 July 2017 / Revised: 27 August 2017 / Accepted: 1 September 2017 / Published: 6 September 2017
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Abstract
The synthesis of highly porous carbon (HPC) materials from poplar catkin by KOH chemical activation and hydrothermal carbonization as a conductive additive to a lithium-sulfur cathode is reported. Elemental sulfur was composited with as-prepared HPC through a melt diffusion method to form a
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The synthesis of highly porous carbon (HPC) materials from poplar catkin by KOH chemical activation and hydrothermal carbonization as a conductive additive to a lithium-sulfur cathode is reported. Elemental sulfur was composited with as-prepared HPC through a melt diffusion method to form a S/HPC nanocomposite. Structure and morphology characterization revealed a hierarchically sponge-like structure of HPC with high pore volume (0.62 cm3∙g−1) and large specific surface area (1261.7 m2∙g−1). When tested in Li/S batteries, the resulting compound demonstrated excellent cycling stability, delivering a second-specific capacity of 1154 mAh∙g−1 as well as presenting 74% retention of value after 100 cycles at 0.1 C. Therefore, the porous structure of HPC plays an important role in enhancing electrochemical properties, which provides conditions for effective charge transfer and effective trapping of soluble polysulfide intermediates, and remarkably improves the electrochemical performance of S/HPC composite cathodes. Full article
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Open AccessArticle Nanosilver–Silica Composite: Prolonged Antibacterial Effects and Bacterial Interaction Mechanisms for Wound Dressings
Nanomaterials 2017, 7(9), 261; doi:10.3390/nano7090261
Received: 24 July 2017 / Revised: 22 August 2017 / Accepted: 3 September 2017 / Published: 6 September 2017
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Abstract
Infected superficial wounds were traditionally controlled by topical antibiotics until the emergence of antibiotic-resistant bacteria. Silver (Ag) is a kernel for alternative antibacterial agents to fight this resistance quandary. The present study demonstrates a method for immobilizing small-sized (~5 nm) silver nanoparticles on
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Infected superficial wounds were traditionally controlled by topical antibiotics until the emergence of antibiotic-resistant bacteria. Silver (Ag) is a kernel for alternative antibacterial agents to fight this resistance quandary. The present study demonstrates a method for immobilizing small-sized (~5 nm) silver nanoparticles on silica matrix to form a nanosilver–silica (Ag–SiO2) composite and shows the prolonged antibacterial effects of the composite in vitro. The composite exhibited a rapid initial Ag release after 24 h and a slower leaching after 48 and 72 h and was effective against both methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli). Ultraviolet (UV)-irradiation was superior to filter-sterilization in retaining the antibacterial effects of the composite, through the higher remaining Ag concentration. A gauze, impregnated with the Ag–SiO2 composite, showed higher antibacterial effects against MRSA and E. coli than a commercial Ag-containing dressing, indicating a potential for the management and infection control of superficial wounds. Transmission and scanning transmission electron microscope analyses of the composite-treated MRSA revealed an interaction of the released silver ions with the bacterial cytoplasmic constituents, causing ultimately the loss of bacterial membranes. The present results indicate that the Ag–SiO2 composite, with prolonged antibacterial effects, is a promising candidate for wound dressing applications. Full article
(This article belongs to the Special Issue Antibacterial Activity of Nanomaterials)
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Open AccessArticle Effects of Various Surfactants on the Dispersion of MWCNTs–OH in Aqueous Solution
Nanomaterials 2017, 7(9), 262; doi:10.3390/nano7090262
Received: 16 July 2017 / Revised: 23 August 2017 / Accepted: 30 August 2017 / Published: 6 September 2017
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Abstract
Dispersion of carbon nanotubes (CNTs) is a challenge for their application in the resulting matrixes. The present study conducted a comparison investigation of the effect of four surfactants: Alkylphenol polyoxyethylene ether (APEO), Silane modified polycarboxylate (Silane-PCE), I-Cationic polycarboxylate (I-C-PCE), and II-Cationic polycarboxylate (II-C-PCE)
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Dispersion of carbon nanotubes (CNTs) is a challenge for their application in the resulting matrixes. The present study conducted a comparison investigation of the effect of four surfactants: Alkylphenol polyoxyethylene ether (APEO), Silane modified polycarboxylate (Silane-PCE), I-Cationic polycarboxylate (I-C-PCE), and II-Cationic polycarboxylate (II-C-PCE) on the dispersion of hydroxyl functionalized multi-walled carbon nanotubes (MWCNTs–OH). Among the four surfactants, APEO and II-C-PCE provide the best and the worst dispersion effect of CNTs in water, respectively. Dispersion effect of MWCNTs–OH has been characterized by optical microscope (OM), field emission-scanning electron microscope (FE-SEM), and Ultraviolet–visible spectroscopy (UV–Vis).The OM images are well consistent with the UV–Vis results. Based on the chemical molecular structures of the four surfactants, the mechanism of MWCNTs–OH dispersion in water was investigated. For each kind of surfactant, an optimum surfactant/MWCNTs–OH ratio has been determined. This ratio showed a significant influence on the dispersion of MWCNTs–OH. Surfactant concentration higher or lower than this value can weaken the dispersion quality of MWCNTs–OH. Full article
(This article belongs to the Special Issue Experimental Nanosciences, Computational Chemistry, and Data Analysis)
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Open AccessArticle Optimizing Melamine Resin Microspheres with Excess Formaldehyde for the SERS Substrate
Nanomaterials 2017, 7(9), 263; doi:10.3390/nano7090263
Received: 9 July 2017 / Revised: 29 August 2017 / Accepted: 1 September 2017 / Published: 6 September 2017
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Abstract
Influence of the excess monomer within the synthetic reaction solution of melamine resin microspheres (MFMSs) on the surface-enhanced Raman spectroscopy (SERS) enhancement from Rhodamine 6G (R6G) was investigated, where the R6G was adsorbed on the silver nanoparticles (AgNPs) that were loaded on the
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Influence of the excess monomer within the synthetic reaction solution of melamine resin microspheres (MFMSs) on the surface-enhanced Raman spectroscopy (SERS) enhancement from Rhodamine 6G (R6G) was investigated, where the R6G was adsorbed on the silver nanoparticles (AgNPs) that were loaded on the MFMSs. Surface characteristics of the MFMSs were modified by the excess monomer (i.e., the excessive melamine or formaldehyde) through its terminal overreaction, which can be simply controlled by some of the synthetic reaction conditions, thus further allowing us to optimize the assembly of the loaded AgNPs for the SERS detection. These SERS substrates incorporating the optimized MFMSs with the excess formaldehyde can also be used for tracing analyses of more environmental and food contaminants. Full article
(This article belongs to the Special Issue Nanomaterials for SERS Applications)
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Open AccessArticle Room Temperature Tunable Multiferroic Properties in Sol-Gel-Derived Nanocrystalline Sr(Ti1−xFex)O3−δ Thin Films
Nanomaterials 2017, 7(9), 264; doi:10.3390/nano7090264
Received: 17 August 2017 / Revised: 2 September 2017 / Accepted: 5 September 2017 / Published: 8 September 2017
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Abstract
Sr(Ti1−xFex)O3−δ (0 ≤ x ≤ 0.2) thin films were grown on Si(100) substrates with LaNiO3 buffer-layer by a sol-gel process. Influence of Fe substitution concentration on the structural, ferroelectric, and magnetic properties, as well as the
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Sr(Ti1−xFex)O3−δ (0 ≤ x ≤ 0.2) thin films were grown on Si(100) substrates with LaNiO3 buffer-layer by a sol-gel process. Influence of Fe substitution concentration on the structural, ferroelectric, and magnetic properties, as well as the leakage current behaviors of the Sr(Ti1−xFex)O3−δ thin films, were investigated by using the X-ray diffractometer (XRD), atomic force microscopy (AFM), the ferroelectric test system, and the vibrating sample magnetometer (VSM). After substituting a small amount of Ti ion with Fe, highly enhanced ferroelectric properties were obtained successfully in SrTi0.9Ti0.1O3−δ thin films, with a double remanent polarization (2Pr) of 1.56, 1.95, and 9.14 μC·cm−2, respectively, for the samples were annealed in air, oxygen, and nitrogen atmospheres. The leakage current densities of the Fe-doped SrTiO3 thin films are about 10−6–10−5 A·cm−2 at an applied electric field of 100 kV·cm−1, and the conduction mechanism of the thin film capacitors with various Fe concentrations has been analyzed. The ferromagnetic properties of the Sr(Ti1−xFex)O3−δ thin films have been investigated, which can be correlated to the mixed valence ions and the effects of the grain boundary. The present results revealed the multiferroic nature of the Sr(Ti1−xFex)O3−δ thin films. The effect of the annealing environment on the room temperature magnetic and ferroelectric properties of Sr(Ti0.9Fe0.1)O3−δ thin films were also discussed in detail. Full article
(This article belongs to the Special Issue Frontiers in Toxicity and Functionalization of Nanomaterials)
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Open AccessArticle Rapid Evaporation of Water on Graphene/Graphene-Oxide: A Molecular Dynamics Study
Nanomaterials 2017, 7(9), 265; doi:10.3390/nano7090265
Received: 6 August 2017 / Revised: 2 September 2017 / Accepted: 5 September 2017 / Published: 7 September 2017
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Abstract
To reveal the mechanism of energy storage in the water/graphene system and water/grapheme-oxide system, the processes of rapid evaporation of water molecules on the sheets of graphene and graphene-oxide are investigated by molecular dynamics simulations. The results show that both the water/graphene and
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To reveal the mechanism of energy storage in the water/graphene system and water/grapheme-oxide system, the processes of rapid evaporation of water molecules on the sheets of graphene and graphene-oxide are investigated by molecular dynamics simulations. The results show that both the water/graphene and water/grapheme-oxide systems can store more energy than the pure water system during evaporation. The hydroxyl groups on the surface of graphene-oxide are able to reduce the attractive interactions between water molecules and the sheet of graphene-oxide. Also, the radial distribution function of the oxygen atom indicates that the hydroxyl groups affect the arrangement of water molecules at the water/graphene-oxide interface. Therefore, the capacity of thermal energy storage of the water/graphene-oxide system is lower than that of the water/graphene system, because of less desorption energy at the water/graphene-oxide interface. Also, the evaporation rate of water molecules on the graphene-oxide sheet is slower than that on the graphene sheet. The Leidenfrost phenomenon can be observed during the evaporation process in the water/grapheme-oxide system. Full article
(This article belongs to the Special Issue Nanomaterials for Renewable and Sustainable Energy)
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Open AccessArticle Growth Method-Dependent and Defect Density-Oriented Structural, Optical, Conductive, and Physical Properties of Solution-Grown ZnO Nanostructures
Nanomaterials 2017, 7(9), 266; doi:10.3390/nano7090266
Received: 1 August 2017 / Revised: 28 August 2017 / Accepted: 7 September 2017 / Published: 10 September 2017
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Abstract
It is time for industry to pay a serious heed to the application and quality-dependent research on the most important solution growth methods for ZnO, namely, aqueous chemical growth (ACG) and microwave-assisted growth (MAG) methods. This study proffers a critical analysis on how
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It is time for industry to pay a serious heed to the application and quality-dependent research on the most important solution growth methods for ZnO, namely, aqueous chemical growth (ACG) and microwave-assisted growth (MAG) methods. This study proffers a critical analysis on how the defect density and formation behavior of ZnO nanostructures (ZNSs) are growth method-dependent. Both antithetical and facile methods are exploited to control the ZnO defect density and the growth mechanism. In this context, the growth of ZnO nanorods (ZNRs), nanoflowers, and nanotubes (ZNTs) are considered. The aforementioned growth methods directly stimulate the nanostructure crystal growth and, depending upon the defect density, ZNSs show different trends in structural, optical, etching, and conductive properties. The defect density of MAG ZNRs is the least because of an ample amount of thermal energy catered by high-power microwaves to the atoms to grow on appropriate crystallographic planes, which is not the case in faulty convective ACG ZNSs. Defect-centric etching of ZNRs into ZNTs is also probed and methodological constraints are proposed. ZNS optical properties are different in the visible region, which are quite peculiar, but outstanding for ZNRs. Hall effect measurements illustrate incongruent conductive trends in both samples. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures)
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Open AccessArticle Mechano-Physical Properties and Microstructure of Carbon Nanotube Reinforced Cement Paste after Thermal Load
Nanomaterials 2017, 7(9), 267; doi:10.3390/nano7090267
Received: 3 August 2017 / Revised: 29 August 2017 / Accepted: 6 September 2017 / Published: 11 September 2017
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Abstract
The article presents the results obtained in the course of a study on the use of carbon nanotubes (CNTs) for the modification of a cement matrix. Carbon nanotubes were introduced into a cement paste in the form of an aqueous dispersion in the
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The article presents the results obtained in the course of a study on the use of carbon nanotubes (CNTs) for the modification of a cement matrix. Carbon nanotubes were introduced into a cement paste in the form of an aqueous dispersion in the presence of a surfactant (SDS—sodium dodecyl sulfate), which was sonicated. The selected physical and mechanical parameters were examined, and the correlations between these parameters were determined. An analysis of the local microstructure of the modified cement pastes has been carried out using scanning electron microscope (SEM) and X-ray microanalysis (EDS). In addition, the effect of carbon nanotubes on the change in characteristics of the cementitious material exposed to the sudden, short-term thermal load, was determined. The obtained material was characterized by a much lower density than a traditional cement matrix because the phenomenon of foaming occurred. The material was also characterized by reduced durability, higher shrinkage, and higher resistance to the effect of elevated temperature. Further research on the carbon nanotube reinforced cement paste, with SDS, may contribute to the development of a modified cement binder for the production of a lightweight or an aerated concrete. Full article
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Open AccessArticle In Vitro Sonodynamic Therapeutic Effect of Polyion Complex Micelles Incorporating Titanium Dioxide Nanoparticles
Nanomaterials 2017, 7(9), 268; doi:10.3390/nano7090268
Received: 1 August 2017 / Revised: 28 August 2017 / Accepted: 6 September 2017 / Published: 11 September 2017
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Abstract
Titanium dioxide nanoparticles (TiO2 NPs) can act as sonosensitizers, generating reactive oxygen species under ultrasound irradiation, for use in sonodynamic therapy. For TiO2 NPs delivery, we prepared polyion complex micelles incorporating TiO2 NPs (TiO2 NPs-PIC micelles) by mixing TiO
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Titanium dioxide nanoparticles (TiO2 NPs) can act as sonosensitizers, generating reactive oxygen species under ultrasound irradiation, for use in sonodynamic therapy. For TiO2 NPs delivery, we prepared polyion complex micelles incorporating TiO2 NPs (TiO2 NPs-PIC micelles) by mixing TiO2 NPs with polyallylamine bearing poly(ethylene glycol) grafts. In this study, the effects of polymer composition and ultrasound irradiation conditions on the sonodynamic therapeutic effect toward HeLa cells were evaluated experimentally using cell viability evaluation, intracellular distribution observation, and a cell staining assay. TiO2 NPs-PIC micelles with widely distributed features induced a significant decrease in cell viability under ultrasound irradiation. Furthermore, prolonging the irradiation time killed cells more effectively than did increasing the ultrasound power. The combination of TiO2 NP-PIC micelles and ultrasound irradiation was confirmed to induce apoptotic cell death. Full article
(This article belongs to the Special Issue ZnO and TiO2 Based Nanostructures)
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Open AccessArticle Near-Infrared-Triggered Photodynamic Therapy toward Breast Cancer Cells Using Dendrimer-Functionalized Upconversion Nanoparticles
Nanomaterials 2017, 7(9), 269; doi:10.3390/nano7090269
Received: 3 August 2017 / Revised: 4 September 2017 / Accepted: 7 September 2017 / Published: 11 September 2017
PDF Full-text (6096 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Water-soluble upconversion nanoparticles (UCNPs) that exhibit significant ultraviolet, blue, and red emissions under 980-nm laser excitation were successfully synthesized for performing near infrared (NIR)-triggered photodynamic therapy (PDT). The lanthanide-doped UCNPs bearing oleate ligands were first exchanged by citrates to generate polyanionic surfaces and
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Water-soluble upconversion nanoparticles (UCNPs) that exhibit significant ultraviolet, blue, and red emissions under 980-nm laser excitation were successfully synthesized for performing near infrared (NIR)-triggered photodynamic therapy (PDT). The lanthanide-doped UCNPs bearing oleate ligands were first exchanged by citrates to generate polyanionic surfaces and then sequentially encapsulated with NH2-terminated poly(amido amine) (PAMAM) dendrimers (G4) and chlorine6 (Ce6) using a layer-by-layer (LBL) absorption strategy. Transmission electron microscopy and X-ray diffraction analysis confirm that the hybrid UCNPs possess a polygonal morphology with an average dimension of 16.0 ± 2.1 nm and α-phase crystallinity. A simple calculation derived through thermogravimetric analysis revealed that one polycationic G4 dendrimer could be firmly accommodated by approximately 150 polyanionic citrates through multivalent interactions. Moreover, zeta potential measurements indicated that the LBL fabrication results in the hybrid nanoparticles with positively charged surfaces originated from these dendrimers, which assist the cellular uptake in biological specimens. The cytotoxic singlet oxygen based on the photosensitization of the adsorbed Ce6 through the upconversion emissions can be readily accumulated by increasing the irradiation time of the incident lasers. Compared with that of 660-nm lasers, NIR-laser excitation exhibits optimized in vitro PDT effects toward human breast cancer MCF-7 cells cultured in the tumorspheres, and less than 40% of cells survived under a low Ce6 dosage of 2.5 × 10−7 M. Fluorescence microscopy analysis indicated that the NIR-driven PDT causes more effective destruction of the cells located inside spheres that exhibit significant cancer stem cell or progenitor cell properties. Moreover, an in vivo assessment based on immunohistochemical analysis for a 4T1 tumor-bearing mouse model confirmed the effective inhibition of cancer cell proliferation through cellular DNA damage by the expression of Ki67 and γH2AXser139 protein markers. Thus, the hybrid UCNPs are a promising NIR-triggered PDT module for cancer treatment. Full article
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Open AccessFeature PaperArticle Retention of Antibacterial Activity in Geranium Plasma Polymer Thin Films
Nanomaterials 2017, 7(9), 270; doi:10.3390/nano7090270
Received: 3 August 2017 / Revised: 5 September 2017 / Accepted: 5 September 2017 / Published: 13 September 2017
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Abstract
Bacterial colonisation of biomedical devices demands novel antibacterial coatings. Plasma-enabled treatment is an established technique for selective modification of physicochemical characteristics of the surface and deposition of polymer thin films. We investigated the retention of inherent antibacterial activity in geranium based plasma polymer
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Bacterial colonisation of biomedical devices demands novel antibacterial coatings. Plasma-enabled treatment is an established technique for selective modification of physicochemical characteristics of the surface and deposition of polymer thin films. We investigated the retention of inherent antibacterial activity in geranium based plasma polymer thin films. Attachment and biofilm formation by Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli was significantly reduced on the surfaces of samples fabricated at 10 W radio frequency (RF) power, compared to that of control or films fabricated at higher input power. This was attributed to lower contact angle and retention of original chemical functionality in the polymer films fabricated under low input power conditions. The topography of all surfaces was uniform and smooth, with surface roughness of 0.18 and 0.69 nm for films fabricated at 10 W and 100 W, respectively. Hardness and elastic modules of films increased with input power. Independent of input power, films were optically transparent within the visible wavelength range, with the main absorption at ~290 nm and optical band gap of ~3.6 eV. These results suggest that geranium extract-derived polymers may potentially be used as antibacterial coatings for contact lenses. Full article
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Open AccessArticle Water Diffusion through a Titanium Dioxide/Poly(Carbonate Urethane) Nanocomposite for Protecting Cultural Heritage: Interactions and Viscoelastic Behavior
Nanomaterials 2017, 7(9), 271; doi:10.3390/nano7090271
Received: 3 July 2017 / Revised: 6 September 2017 / Accepted: 7 September 2017 / Published: 13 September 2017
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Abstract
Water diffusion through a TiO2/poly (carbonate urethane) nanocomposite designed for the eco-sustainable protection of outdoor cultural heritage stonework was investigated. Water is recognized as a threat to heritage, hence the aim was to gather information on the amount of water uptake,
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Water diffusion through a TiO2/poly (carbonate urethane) nanocomposite designed for the eco-sustainable protection of outdoor cultural heritage stonework was investigated. Water is recognized as a threat to heritage, hence the aim was to gather information on the amount of water uptake, as well as of species of water molecules absorbed within the polymer matrix. Gravimetric and vibrational spectroscopy measurements demonstrated that diffusion behavior of the nanocomposite/water system is Fickian, i.e., diffusivity is independent of concentration. The addition of only 1% of TiO2 nanoparticles strongly betters PU barrier properties and water-repellency requirement is imparted. Defensive action against penetration of water free from, and bonded through, H-bonding association arises from balance among TiO2 hydrophilicity, tortuosity effects and quality of nanoparticle dispersion and interfacial interactions. Further beneficial to antisoiling/antigraffiti action is that water-free fraction was found to be desorbed at a constant rate. In environmental conditions, under which weathering processes are most likely to occur, nanocomposite Tg values remain suitable for heritage treatments. Full article
(This article belongs to the Special Issue Polymer Nanocomposites)
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Open AccessArticle Comparison of Ti-Based Coatings on Silicon Nanowires for Phosphopeptide Enrichment and Their Laser Assisted Desorption/Ionization Mass Spectrometry Detection
Nanomaterials 2017, 7(9), 272; doi:10.3390/nano7090272
Received: 15 August 2017 / Revised: 4 September 2017 / Accepted: 9 September 2017 / Published: 15 September 2017
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Abstract
We created different TiO2-based coatings on silicon nanowires (SiNWs) by using either thermal metallization or atomic layer deposition (ALD). The fabricated surfaces were characterized by X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), and reflectivity measurements. Surfaces with different TiO
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We created different TiO2-based coatings on silicon nanowires (SiNWs) by using either thermal metallization or atomic layer deposition (ALD). The fabricated surfaces were characterized by X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), and reflectivity measurements. Surfaces with different TiO2 based coating thicknesses were then used for phosphopeptide enrichment and subsequent detection by laser desorption/ionization mass spectrometry (LDI-MS). Results showed that the best enrichment and LDI-MS detection were obtained using the silicon nanowires covered with 10 nm of oxidized Ti deposited by means of thermal evaporation. This sample was also able to perform phosphopeptide enrichment and MS detection from serum. Full article
(This article belongs to the Special Issue Nanomaterials for Mass Spectrometry Applications)
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Open AccessArticle Construction of Hierarchical CuO/Cu2O@NiCo2S4 Nanowire Arrays on Copper Foam for High Performance Supercapacitor Electrodes
Nanomaterials 2017, 7(9), 273; doi:10.3390/nano7090273
Received: 13 August 2017 / Revised: 11 September 2017 / Accepted: 11 September 2017 / Published: 15 September 2017
Cited by 1 | PDF Full-text (1970 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Hierarchical copper oxide @ ternary nickel cobalt sulfide (CuO/Cu2O@NiCo2S4) core-shell nanowire arrays on Cu foam have been successfully constructed by a facile two-step strategy. Vertically aligned CuO/Cu2O nanowire arrays are firstly grown on Cu foam
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Hierarchical copper oxide @ ternary nickel cobalt sulfide (CuO/Cu2O@NiCo2S4) core-shell nanowire arrays on Cu foam have been successfully constructed by a facile two-step strategy. Vertically aligned CuO/Cu2O nanowire arrays are firstly grown on Cu foam by one-step thermal oxidation of Cu foam, followed by electrodeposition of NiCo2S4 nanosheets on the surface of CuO/Cu2O nanowires to form the CuO/Cu2O@NiCo2S4 core-shell nanostructures. Structural and morphological characterizations indicate that the average thickness of the NiCo2S4 nanosheets is ~20 nm and the diameter of CuO/Cu2O core is ~50 nm. Electrochemical properties of the hierarchical composites as integrated binder-free electrodes for supercapacitor were evaluated by various electrochemical methods. The hierarchical composite electrodes could achieve ultrahigh specific capacitance of 3.186 F cm−2 at 10 mA cm−2, good rate capability (82.06% capacitance retention at the current density from 2 to 50 mA cm−2) and excellent cycling stability, with capacitance retention of 96.73% after 2000 cycles at 10 mA cm−2. These results demonstrate the significance of optimized design and fabrication of electrode materials with more sufficient electrolyte-electrode interface, robust structural integrity and fast ion/electron transfer. Full article
(This article belongs to the Special Issue Nanomaterials Based Fuel Cells and Supercapacitors)
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Open AccessArticle Biocompatibility of Titania Nanotube Coatings Enriched with Silver Nanograins by Chemical Vapor Deposition
Nanomaterials 2017, 7(9), 274; doi:10.3390/nano7090274
Received: 7 August 2017 / Revised: 9 September 2017 / Accepted: 12 September 2017 / Published: 15 September 2017
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Abstract
Bioactivity investigations of titania nanotube (TNT) coatings enriched with silver nanograins (TNT/Ag) have been carried out. TNT/Ag nanocomposite materials were produced by combining the electrochemical anodization and chemical vapor deposition methods. Fabricated coatings were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy
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Bioactivity investigations of titania nanotube (TNT) coatings enriched with silver nanograins (TNT/Ag) have been carried out. TNT/Ag nanocomposite materials were produced by combining the electrochemical anodization and chemical vapor deposition methods. Fabricated coatings were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The release effect of silver ions from TNT/Ag composites immersed in bodily fluids, has been studied using inductively coupled plasma mass spectrometry (ICP-MS). The metabolic activity assay (MTT) was applied to determine the L929 murine fibroblasts adhesion and proliferation on the surface of TNT/Ag coatings. Moreover, the results of immunoassays (using peripheral blood mononuclear cells—PBMCs isolated from rats) allowed the estimation of the immunological activity of TNT/Ag surface materials. Antibacterial activity of TNT/Ag coatings with different morphological and structural features was estimated against two Staphylococcus aureus strains (ATCC 29213 and H9). The TNT/Ag nanocomposite layers produced revealed a good biocompatibility promoting the fibroblast adhesion and proliferation. A desirable anti-biofilm activity against the S. aureus reference strain was mainly noticed for these TiO2 nanotube coatings, which contain dispersed Ag nanograins deposited on their surface. Full article
(This article belongs to the Special Issue Nanoparticles in Immunology)
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Open AccessArticle Field Emission from Self-Catalyzed GaAs Nanowires
Nanomaterials 2017, 7(9), 275; doi:10.3390/nano7090275
Received: 23 August 2017 / Revised: 12 September 2017 / Accepted: 13 September 2017 / Published: 16 September 2017
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Abstract
We report observations of field emission from self-catalyzed GaAs nanowires grown on Si (111). The measurements were taken inside a scanning electron microscope chamber with a nano-controlled tungsten tip functioning as anode. Experimental data were analyzed in the framework of the Fowler-Nordheim theory.
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We report observations of field emission from self-catalyzed GaAs nanowires grown on Si (111). The measurements were taken inside a scanning electron microscope chamber with a nano-controlled tungsten tip functioning as anode. Experimental data were analyzed in the framework of the Fowler-Nordheim theory. We demonstrate stable current up to 10−7 A emitted from the tip of single nanowire, with a field enhancement factor β of up to 112 at anode-cathode distance d = 350 nm. A linear dependence of β on the anode-cathode distance was found. We also show that the presence of a Ga catalyst droplet suppresses the emission of current from the nanowire tip. This allowed for the detection of field emission from the nanowire sidewalls, which occurred with a reduced field enhancement factor and stability. This study further extends GaAs technology to vacuum electronics applications. Full article
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Open AccessArticle Preparation, Characterization, and Preliminary In Vitro Testing of Nanoceria-Loaded Liposomes
Nanomaterials 2017, 7(9), 276; doi:10.3390/nano7090276
Received: 4 August 2017 / Revised: 13 September 2017 / Accepted: 14 September 2017 / Published: 16 September 2017
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Abstract
Cerium oxide nanoparticles (nanoceria), well known for their pro- and antioxidant features, have been recently proposed for the treatment of several pathologies, including cancer and neurodegenerative diseases. However, interaction between nanoceria and biological molecules such as proteins and lipids, short blood circulation time,
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Cerium oxide nanoparticles (nanoceria), well known for their pro- and antioxidant features, have been recently proposed for the treatment of several pathologies, including cancer and neurodegenerative diseases. However, interaction between nanoceria and biological molecules such as proteins and lipids, short blood circulation time, and the need of a targeted delivery to desired sites are some aspects that require strong attention for further progresses in the clinical application of these nanoparticles. The aim of this work is the encapsulation of nanoceria into a liposomal formulation in order to improve their therapeutic potentialities. After the preparation through a reverse-phase evaporation method, size, Z-potential, morphology, and loading efficiency of nanoceria-loaded liposomes were investigated. Finally, preliminary in vitro studies were performed to test cell uptake efficiency and preserved antioxidant activity. Nanoceria-loaded liposomes showed a good colloidal stability, an excellent biocompatibility, and strong antioxidant properties due to the unaltered activity of the entrapped nanoceria. With these results, the possibility of exploiting liposomes as carriers for cerium oxide nanoparticles is demonstrated here for the first time, thus opening exciting new opportunities for in vivo applications. Full article
(This article belongs to the Special Issue Nanocolloids for Nanomedicine and Drug delivery)
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Open AccessArticle Fabrication of Magnetic Nanofibers by Needleless Electrospinning from a Self-Assembling Polymer Ferrofluid Cone Array
Nanomaterials 2017, 7(9), 277; doi:10.3390/nano7090277
Received: 20 August 2017 / Revised: 12 September 2017 / Accepted: 13 September 2017 / Published: 17 September 2017
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Abstract
Magnetic nanofiber has been widely applied in biomedical fields due to its distinctive size, morphology, and properties. We proposed a novel needleless electrospinning method to prepare magnetic nanofibers from the self-assembling “Taylor cones” of poly(vinyl pyrrolidone) (PVP)/Fe3O4 ferrofluid (PFF) under
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Magnetic nanofiber has been widely applied in biomedical fields due to its distinctive size, morphology, and properties. We proposed a novel needleless electrospinning method to prepare magnetic nanofibers from the self-assembling “Taylor cones” of poly(vinyl pyrrolidone) (PVP)/Fe3O4 ferrofluid (PFF) under the coincident magnetic and electric fields. The results demonstrated that a static PFF Rosensweig instability with a conical protrusion could be obtained under the magnetic field. The tip of the protrusion emitted an electrospinning jet under the coincident magnetic and electric fields. The needleless electrospinning showed a similar process phenomenon in comparison with conventional electrospinning. The prepared nanofibers were composed of Fe3O4 particles and PVP polymer. The Fe3O4 particles aggregated inside and on the surface of the nanofibers. The nanofibers prepared by needleless electrospinning exhibited similar morphology compared with the conventionally electrospun nanofibers. The nanofibers also exhibited good ferromagnetic and magnetic field responsive properties. Full article
(This article belongs to the Special Issue The Fabrication and Application of Nanofibers)
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Open AccessArticle Acetylene Gas-Sensing Properties of Layer-by-Layer Self-Assembled Ag-Decorated Tin Dioxide/Graphene Nanocomposite Film
Nanomaterials 2017, 7(9), 278; doi:10.3390/nano7090278
Received: 22 August 2017 / Revised: 10 September 2017 / Accepted: 14 September 2017 / Published: 18 September 2017
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Abstract
This paper demonstrates an acetylene gas sensor based on an Ag-decorated tin dioxide/reduced graphene oxide (Ag–SnO2/rGO) nanocomposite film, prepared by layer-by-layer (LbL) self-assembly technology. The as-prepared Ag–SnO2/rGO nanocomposite was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM),
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This paper demonstrates an acetylene gas sensor based on an Ag-decorated tin dioxide/reduced graphene oxide (Ag–SnO2/rGO) nanocomposite film, prepared by layer-by-layer (LbL) self-assembly technology. The as-prepared Ag–SnO2/rGO nanocomposite was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectrum. The acetylene sensing properties were investigated using different working temperatures and gas concentrations. An optimal temperature of 90 °C was determined, and the Ag–SnO2/rGO nanocomposite sensor exhibited excellent sensing behaviors towards acetylene, in terms of response, repeatability, stability and response/recovery characteristics, which were superior to the pure SnO2 and SnO2/rGO film sensors. The sensing mechanism of the Ag–SnO2/rGO sensor was attributed to the synergistic effect of the ternary nanomaterials, and the heterojunctions created at the interfaces between SnO2 and rGO. This work indicates that the Ag–SnO2/rGO nanocomposite is a good candidate for constructing a low-temperature acetylene sensor. Full article
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Open AccessArticle Development and Biocompatibility Evaluation of Photocatalytic TiO2/Reduced Graphene Oxide-Based Nanoparticles Designed for Self-Cleaning Purposes
Nanomaterials 2017, 7(9), 279; doi:10.3390/nano7090279
Received: 4 August 2017 / Revised: 11 September 2017 / Accepted: 14 September 2017 / Published: 19 September 2017
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Abstract
Graphene is widely used in nanotechnologies to amplify the photocatalytic activity of TiO2, but the development of TiO2/graphene composites imposes the assessment of their risk to human and environmental health. Therefore, reduced graphene oxide was decorated with two types
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Graphene is widely used in nanotechnologies to amplify the photocatalytic activity of TiO2, but the development of TiO2/graphene composites imposes the assessment of their risk to human and environmental health. Therefore, reduced graphene oxide was decorated with two types of TiO2 particles co-doped with 1% iron and nitrogen, one of them being obtained by a simultaneous precipitation of Ti3+ and Fe3+ ions to achieve their uniform distribution, and the other one after a sequential precipitation of these two cations for a higher concentration of iron on the surface. Physico-chemical characterization, photocatalytic efficiency evaluation, antimicrobial analysis and biocompatibility assessment were performed for these TiO2-based composites. The best photocatalytic efficiency was found for the sample with iron atoms localized at the sample surface. A very good anti-inhibitory activity was obtained for both samples against biofilms of Gram-positive and Gram-negative strains. Exposure of human skin and lung fibroblasts to photocatalysts did not significantly affect cell viability, but analysis of oxidative stress showed increased levels of carbonyl groups and advanced oxidation protein products for both cell lines after 48 h of incubation. Our findings are of major importance by providing useful knowledge for future photocatalytic self-cleaning and biomedical applications of graphene-based materials. Full article
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Open AccessArticle Differential Effects of Surface-Functionalized Zirconium Oxide Nanoparticles on Alveolar Macrophages, Rat Lung, and a Mouse Allergy Model
Nanomaterials 2017, 7(9), 280; doi:10.3390/nano7090280
Received: 21 August 2017 / Revised: 11 September 2017 / Accepted: 12 September 2017 / Published: 19 September 2017
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Abstract
Nanoparticles (NPs) may affect the lung via their chemical composition on the surface. Here, we compared the bioactivity of zirconium oxide (ZrO2) NPs coated with either aminopropilsilane (APTS), tetraoxidecanoic acid (TODS), polyethyleneglycol (PGA), or acrylic acid (Acryl). Supernatants from NPs-treated cultured
[...] Read more.
Nanoparticles (NPs) may affect the lung via their chemical composition on the surface. Here, we compared the bioactivity of zirconium oxide (ZrO2) NPs coated with either aminopropilsilane (APTS), tetraoxidecanoic acid (TODS), polyethyleneglycol (PGA), or acrylic acid (Acryl). Supernatants from NPs-treated cultured alveolar macrophages (NR8383) tested for lactate dehydrogenase, glucuronidase, tumor necrosis factor α, and H2O2 formation revealed dose-dependent effects, with only gradual differences among particles whose gravitational settling and cellular uptake were similar. We selected TODS- and Acryl-coated NPs for intratracheal administration into the rat lung. Darkfield and hyperspectral microscopy combined with immunocytochemistry showed that both NPs qualities accumulate mainly within the alveolar macrophage compartment, although minute amounts also occurred in neutrophilic granulocytes. Dose-dependent signs of inflammation were found in the broncho-alveolar lavage fluid on day 3 but no longer on day 21 post-application of ≥1.2 mg per lung; again only minor differences occurred between TODS- and Acryl-coated NPs. In contrast, the response of allergic mice was overall higher compared to control mice and dependent on the surface modification. Increases in eosinophils, lymphocytes and macrophages were highest following ZrO2-PGA administration, followed by ZrO2-Acryl, ZrO2-TODS, and ZrO2-APTS. We conclude that surface functionalization of ZrO2 NPs has minor effects on the inflammatory lung response of rats and mice, but is most relevant for an allergic mouse model. Allergic individuals may therefore be more susceptible to exposure to NPs with specific surface modifications. Full article
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Open AccessArticle Transparent Pullulan/Mica Nanocomposite Coatings with Outstanding Oxygen Barrier Properties
Nanomaterials 2017, 7(9), 281; doi:10.3390/nano7090281
Received: 31 August 2017 / Revised: 14 September 2017 / Accepted: 15 September 2017 / Published: 19 September 2017
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Abstract
This study presents a new bionanocomposite coating on poly(ethylene terephthalate) (PET) made of pullulan and synthetic mica. Mica nanolayers have a very high aspect ratio (α), at levels much greater than that of conventional exfoliated clay layers (e.g., montmorillonite). A very small amount
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This study presents a new bionanocomposite coating on poly(ethylene terephthalate) (PET) made of pullulan and synthetic mica. Mica nanolayers have a very high aspect ratio (α), at levels much greater than that of conventional exfoliated clay layers (e.g., montmorillonite). A very small amount of mica (0.02 wt %, which is ϕ ≈ 0.00008) in pullulan coatings dramatically improved the oxygen barrier performance of the nanocomposite films under dry conditions, however, this performance was partly lost as the environmental relative humidity (RH) increased. This outcome was explained in terms of the perturbation of the spatial ordering of mica sheets within the main pullulan phase, because of RH fluctuations. This was confirmed by modelling of the experimental oxygen transmission rate (OTR) data according to Cussler’s model. The presence of the synthetic nanobuilding block (NBB) led to a decrease in both static and kinetic coefficients of friction, compared with neat PET (≈12% and 23%, respectively) and PET coated with unloaded pullulan (≈26% reduction in both coefficients). In spite of the presence of the filler, all of the coating formulations did not significantly impair the overall optical properties of the final material, which exhibited haze values below 3% and transmittance above 85%. The only exception to this was represented by the formulation with the highest loading of mica (1.5 wt %, which is ϕ ≈ 0.01). These findings revealed, for the first time, the potential of the NBB mica to produce nanocomposite coatings in combination with biopolymers for the generation of new functional features, such as transparent high oxygen barrier materials. Full article
(This article belongs to the Special Issue Polymer Nanocomposites)
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Open AccessArticle Bioaccessibility and Cellular Uptake of β-Carotene Encapsulated in Model O/W Emulsions: Influence of Initial Droplet Size and Emulsifiers
Nanomaterials 2017, 7(9), 282; doi:10.3390/nano7090282
Received: 16 August 2017 / Revised: 1 September 2017 / Accepted: 15 September 2017 / Published: 20 September 2017
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Abstract
The effects of the initial emulsion structure (droplet size and emulsifier) on the properties of β-carotene-loaded emulsions and the bioavailability of β-carotene after passing through simulated gastrointestinal tract (GIT) digestion were investigated. Exposure to GIT significantly changed the droplet size, surface charge and
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The effects of the initial emulsion structure (droplet size and emulsifier) on the properties of β-carotene-loaded emulsions and the bioavailability of β-carotene after passing through simulated gastrointestinal tract (GIT) digestion were investigated. Exposure to GIT significantly changed the droplet size, surface charge and composition of all emulsions, and these changes were dependent on their initial droplet size and the emulsifiers used. Whey protein isolate (WPI)-stabilized emulsion showed the highest β-carotene bioaccessibility, while sodium caseinate (SCN)-stabilized emulsion showed the highest cellular uptake of β-carotene. The bioavailability of emulsion-encapsulated β-carotene based on the results of bioaccessibility and cellular uptake showed the same order with the results of cellular uptake being SCN > TW80 > WPI. An inconsistency between the results of bioaccessibility and bioavailability was observed, indicating that the cellular uptake assay is necessary for a reliable evaluation of the bioavailability of emulsion-encapsulated compounds. The findings in this study contribute to a better understanding of the correlation between emulsion structure and the digestive fate of emulsion-encapsulated nutrients, which make it possible to achieve controlled or potential targeted delivery of nutrients by designing the structure of emulsion-based carriers. Full article
(This article belongs to the Special Issue Nanomaterials in Food Safety)
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Open AccessReview Magnetic Nanoparticles: From Design and Synthesis to Real World Applications
Nanomaterials 2017, 7(9), 243; doi:10.3390/nano7090243
Received: 30 June 2017 / Revised: 21 August 2017 / Accepted: 22 August 2017 / Published: 29 August 2017
Cited by 1 | PDF Full-text (2847 KB) | HTML Full-text | XML Full-text
Abstract
The increasing number of scientific publications focusing on magnetic materials indicates growing interest in the broader scientific community. Substantial progress was made in the synthesis of magnetic materials of desired size, morphology, chemical composition, and surface chemistry. Physical and chemical stability of magnetic
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The increasing number of scientific publications focusing on magnetic materials indicates growing interest in the broader scientific community. Substantial progress was made in the synthesis of magnetic materials of desired size, morphology, chemical composition, and surface chemistry. Physical and chemical stability of magnetic materials is acquired by the coating. Moreover, surface layers of polymers, silica, biomolecules, etc. can be designed to obtain affinity to target molecules. The combination of the ability to respond to the external magnetic field and the rich possibilities of coatings makes magnetic materials universal tool for magnetic separations of small molecules, biomolecules and cells. In the biomedical field, magnetic particles and magnetic composites are utilized as the drug carriers, as contrast agents for magnetic resonance imaging (MRI), and in magnetic hyperthermia. However, the multifunctional magnetic particles enabling the diagnosis and therapy at the same time are emerging. The presented review article summarizes the findings regarding the design and synthesis of magnetic materials focused on biomedical applications. We highlight the utilization of magnetic materials in separation/preconcentration of various molecules and cells, and their use in diagnosis and therapy. Full article
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Open AccessReview Mini Review: Nanosheet Technology towards Biomedical Application
Nanomaterials 2017, 7(9), 246; doi:10.3390/nano7090246
Received: 7 August 2017 / Revised: 26 August 2017 / Accepted: 28 August 2017 / Published: 31 August 2017
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Abstract
The fabrication technique of ultrathin film (commonly known as nanosheets) has been significantly developed over the years. Due to the mechanical properties of nanosheets, such as high levels of adhesion and flexibility, this made nanosheets the ideal candidate in biomedical applications. In this
[...] Read more.
The fabrication technique of ultrathin film (commonly known as nanosheets) has been significantly developed over the years. Due to the mechanical properties of nanosheets, such as high levels of adhesion and flexibility, this made nanosheets the ideal candidate in biomedical applications. In this review, innovative biomedical applications of nanosheets are discussed, which include, drug delivery, wound treatment, and functional nanosheets towards flexible biodevices, etc. Finally, the future outlook of nanosheet technology towards a biomedical application is discussed. Full article
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Open AccessReview Pro-Inflammatory Versus Anti-Inflammatory Effects of Dendrimers: The Two Faces of Immuno-Modulatory Nanoparticles
Nanomaterials 2017, 7(9), 251; doi:10.3390/nano7090251
Received: 21 July 2017 / Revised: 25 August 2017 / Accepted: 30 August 2017 / Published: 1 September 2017
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Abstract
Dendrimers are soft matter, hyperbranched, and multivalent nanoparticles whose synthesis theoretically affords monodisperse compounds. They are built from a core on which one or several successive series of branches are engrafted in an arborescent way. At the end of the synthesis, the tunable
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Dendrimers are soft matter, hyperbranched, and multivalent nanoparticles whose synthesis theoretically affords monodisperse compounds. They are built from a core on which one or several successive series of branches are engrafted in an arborescent way. At the end of the synthesis, the tunable addition of surface groups gives birth to multivalent nano-objects which are generally intended for a specific use. For these reasons, dendrimers have received a lot of attention from biomedical researchers. In particular, some of us have demonstrated that dendrimers can be intrinsically drug-candidate for the treatment of inflammatory disorders, amongst others, using relevant preclinical animal models. These anti-inflammatory dendrimers are innovative in the pharmaceutical field. More recently, it has appeared that some dendrimers (even among those which have been described as anti-inflammatory) can promote inflammatory responses in non-diseased animals. The main corpus of this concise review is focused on the reports which describe anti-inflammatory properties of dendrimers in vivo, following which we review the few recent articles that show pro-inflammatory effects of our favorite molecules, to finally discuss this duality in immuno-modulation which has to be taken into account for the preclinical and clinical developments of dendrimers. Full article
(This article belongs to the Special Issue Nanoparticles in Immunology)
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Open AccessReview Production and Status of Bacterial Cellulose in Biomedical Engineering
Nanomaterials 2017, 7(9), 257; doi:10.3390/nano7090257
Received: 29 June 2017 / Revised: 30 August 2017 / Accepted: 1 September 2017 / Published: 4 September 2017
Cited by 1 | PDF Full-text (14392 KB) | HTML Full-text | XML Full-text
Abstract
Bacterial cellulose (BC) is a highly pure and crystalline material generated by aerobic bacteria, which has received significant interest due to its unique physiochemical characteristics in comparison with plant cellulose. BC, alone or in combination with different components (e.g., biopolymers and nanoparticles), can
[...] Read more.
Bacterial cellulose (BC) is a highly pure and crystalline material generated by aerobic bacteria, which has received significant interest due to its unique physiochemical characteristics in comparison with plant cellulose. BC, alone or in combination with different components (e.g., biopolymers and nanoparticles), can be used for a wide range of applications, such as medical products, electrical instruments, and food ingredients. In recent years, biomedical devices have gained important attention due to the increase in medical engineering products for wound care, regeneration of organs, diagnosis of diseases, and drug transportation. Bacterial cellulose has potential applications across several medical sectors and permits the development of innovative materials. This paper reviews the progress of related research, including overall information about bacterial cellulose, production by microorganisms, mechanisms as well as BC cultivation and its nanocomposites. The latest use of BC in the biomedical field is thoroughly discussed with its applications in both a pure and composite form. This paper concludes the further investigations of BC in the future that are required to make it marketable in vital biomaterials. Full article
(This article belongs to the Special Issue Nanofibrous Scaffolds for Biomedical Application)
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