Nanomaterials

10 pages, 1431 KiB

Open AccessArticle

Optical Properties of Graphene/MoS₂ Heterostructure: First Principles Calculations

by Bin Qiu, Xiuwen Zhao, Guichao Hu, Weiwei Yue, Junfeng Ren and Xiaobo Yuan

Nanomaterials 2018, 8(11), 962; https://doi.org/10.3390/nano8110962 - 21 Nov 2018

Cited by 69 | Viewed by 8661

The electronic structure and the optical properties of Graphene/MoS₂ heterostructure (GM) are studied based on density functional theory. Compared with single-layer graphene, the bandgap will be opened; however, the bandgap will be reduced significantly when compared with single-layer MoS₂. Redshifts [...] Read more.

The electronic structure and the optical properties of Graphene/MoS₂ heterostructure (GM) are studied based on density functional theory. Compared with single-layer graphene, the bandgap will be opened; however, the bandgap will be reduced significantly when compared with single-layer MoS₂. Redshifts of the absorption coefficient, refractive index, and the reflectance appear in the GM system; however, blueshift is found for the energy loss spectrum. Electronic structure and optical properties of single-layer graphene and MoS₂ are changed after they are combined to form the heterostructure, which broadens the extensive developments of two-dimensional materials. Full article

(This article belongs to the Special Issue 2D Materials and Van der Waals Heterostructures: Physics and Applications)

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12 pages, 24150 KiB

Open AccessArticle

Design and Evaluation of Europium Containing Mesoporous Bioactive Glass Nanospheres: Doxorubicin Release Kinetics and Inhibitory Effect on Osteosarcoma MG 63 Cells

by Ying Zhang, Meng Hu, Xiang Wang, Zhufa Zhou and Yu Liu

Nanomaterials 2018, 8(11), 961; https://doi.org/10.3390/nano8110961 - 21 Nov 2018

Cited by 30 | Viewed by 3776

Abstract

Functional ions and drug factors play a vital role in stimulating bone tissue regeneration as we understand it. In this work, europium-containing mesoporous bioactive glass nanospheres (Eu/MBGs), composed of 60% SiO₂—(36–x)%CaO—x%Eu₂O₃—4%P₂O₅ (x = 0, [...] Read more.

Functional ions and drug factors play a vital role in stimulating bone tissue regeneration as we understand it. In this work, europium-containing mesoporous bioactive glass nanospheres (Eu/MBGs), composed of 60% SiO₂—(36–x)%CaO—x%Eu₂O₃—4%P₂O₅ (x = 0, 0.5, 1, 2 mol%), were prepared by a facile sol-gel process. The results indicate that Eu ions play an important role to influence the microstructure of MBGs, in which a suitable concentration of Eu (1 mol%) increases their surface area (502 m²/g) as well as their pore volume (0.34 cm³/g). Proper doping of Eu ions in MBGs can observably induce apatite mineralization and improve the doxorubicin (DOX) release behavior. Furthermore, DOX-loaded Eu/MBGs could maintain a long-term inhibitory effect on the viability of osteosarcoma MG 63 cells. This work has demonstrated that it is possible to develop functional Eu/MBGs by combining excellent apatite-mineralization ability, controllable drug (DOX) release and antitumor functions for the therapy of bone tissue regeneration. Full article

(This article belongs to the Special Issue Sol-Gel Preparation of Nanomaterials)

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15 pages, 1980 KiB

Open AccessReview

Scaffold Structural Microenvironmental Cues to Guide Tissue Regeneration in Bone Tissue Applications

by Xuening Chen, Hongyuan Fan, Xiaowei Deng, Lina Wu, Tao Yi, Linxia Gu, Changchun Zhou, Yujiang Fan and Xingdong Zhang

Nanomaterials 2018, 8(11), 960; https://doi.org/10.3390/nano8110960 - 21 Nov 2018

Cited by 157 | Viewed by 12685

Abstract

In the process of bone regeneration, new bone formation is largely affected by physico-chemical cues in the surrounding microenvironment. Tissue cells reside in a complex scaffold physiological microenvironment. The scaffold should provide certain circumstance full of structural cues to enhance multipotent mesenchymal stem [...] Read more.

In the process of bone regeneration, new bone formation is largely affected by physico-chemical cues in the surrounding microenvironment. Tissue cells reside in a complex scaffold physiological microenvironment. The scaffold should provide certain circumstance full of structural cues to enhance multipotent mesenchymal stem cell (MSC) differentiation, osteoblast growth, extracellular matrix (ECM) deposition, and subsequent new bone formation. This article reviewed advances in fabrication technology that enable the creation of biomaterials with well-defined pore structure and surface topography, which can be sensed by host tissue cells (esp., stem cells) and subsequently determine cell fates during differentiation. Three important cues, including scaffold pore structure (i.e., porosity and pore size), grain size, and surface topography were studied. These findings improve our understanding of how the mechanism scaffold microenvironmental cues guide bone tissue regeneration. Full article

(This article belongs to the Special Issue Nanoscale Materials and Technologies in Tissue Engineering)

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11 pages, 2811 KiB

Open AccessArticle

Size Fractionation of Fluorescent Graphene Quantum Dots Using a Cross-Flow Membrane Filtration System

by Sang-Gu Yim, Yong Jin Kim, Ye-Eun Kang, Byung Kee Moon, Eun Sang Jung and Seung Yun Yang

Nanomaterials 2018, 8(11), 959; https://doi.org/10.3390/nano8110959 - 21 Nov 2018

Cited by 10 | Viewed by 4898

Abstract

Graphene quantum dots (GQDs) have received great attention as optical agents because of their low toxicity, stable photoluminescence (PL) in moderate pH solutions, and size-dependent optical properties. Although many synthetic routes have been proposed for producing GQD solutions, the broad size distribution in [...] Read more.

Graphene quantum dots (GQDs) have received great attention as optical agents because of their low toxicity, stable photoluminescence (PL) in moderate pH solutions, and size-dependent optical properties. Although many synthetic routes have been proposed for producing GQD solutions, the broad size distribution in GQD solutions limits its use as an efficient optical agent. Here, we present a straightforward method for size fractionation of GQDs dispersed in water using a cross-flow filtration system and a track-etched membrane with cylindrical uniform nanopores. The GQD aqueous suspension, which primarily contained blue-emitting GQDs (B-GQDs) and green-emitting GQDs (G-GQDs), was introduced to the membrane in tangential flow and was fractionated with a constant permeate flow of about 800 L m⁻² h⁻¹ bar⁻¹. After filtration, we observed a clear blue PL spectrum from the permeate side, which can be attributed to selective permeation of relatively small B-GQDs. The process provided a separation factor (B-GQDs/G-GQDs) of 0.74. In the cross-flow filtration system, size-dependent permeation through cylindrical nanochannels was confirmed by simulation. Our results demonstrate a feasible method facilitating size fractionation of two-dimensional nanostructures using a cross-flow membrane filtration system. Since membrane filtration is simple, cost-effective, and scalable, our approach can be applied to prepare a large amount of size-controlled GQDs required for high performance opto-electronics and bio-imaging applications. Full article

(This article belongs to the Special Issue Graphene-Based Nanostructures and Optoelectronic Applications)

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16 pages, 3014 KiB

Open AccessArticle

A DFT Screening of M-HKUST-1 MOFs for Nitrogen-Containing Compounds Adsorption

by Shibiao Zong, Yajing Zhang, Na Lu, Pan Ma, Jianguo Wang and Xue-Rong Shi

Nanomaterials 2018, 8(11), 958; https://doi.org/10.3390/nano8110958 - 20 Nov 2018

Cited by 16 | Viewed by 5368

Abstract

To develop promising adsorbent candidates for adsorptive denitrogenation, we screened the adsorption of NO, NO₂, and NH₃ in 19 M-HKUST-1 (M = Be, Fe, Ni, Cr, Co, Cu, V, Zn, Mo, Mn, W, Sn, Ti, Cd, Mg, Sc, Ca, Sr, [...] Read more.

To develop promising adsorbent candidates for adsorptive denitrogenation, we screened the adsorption of NO, NO₂, and NH₃ in 19 M-HKUST-1 (M = Be, Fe, Ni, Cr, Co, Cu, V, Zn, Mo, Mn, W, Sn, Ti, Cd, Mg, Sc, Ca, Sr, and Ba) systematically using first-principle calculations. Of these, four variants of M-HKUST-1 (M = Ni, Co, V, and Sc) yield more negative adsorption Gibbs free energy ΔG_ads than the original Cu-HKUST-1 for three adsorbates, suggesting stronger adsorbate binding. Ti-HKUST-1, Sc-HKUST-1, and Be-HKUST-1 are predicted to have the largest NO, NO₂, and NH₃ adsorption energies within the screened M-HKUST-1 series, respectively. With the one exception of NO₂ dissociation on V-HKUST-1, dissociative adsorption of NO, NO₂, and NH₃ molecules on the other considered M-HKUST-1 is energetically less favorable than molecular adsorption thermodynamically. The barrier calculations show that the dissociation is difficult to occur on Cu-HKUST-1 kinetically due to the very large dissociation barrier. Electronic analysis is provided to explain the bond nature between the adsorbates and M-HKUST-1. Note that the isostructural substitution of Cu to the other metals is a major simplification of the system, representing the ideal situation; however, the present study provides interesting targets for experimental synthesis and testing. Full article

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15 pages, 3954 KiB

Open AccessArticle

Efficient Removal of Lead, Copper and Cadmium Ions from Water by a Porous Calcium Alginate/Graphene Oxide Composite Aerogel

by Linhai Pan, Zhuqing Wang, Qi Yang and Rongyi Huang

Nanomaterials 2018, 8(11), 957; https://doi.org/10.3390/nano8110957 - 20 Nov 2018

Cited by 109 | Viewed by 6140

Abstract

In this study, we fabricated a porous calcium alginate/graphene oxide composite aerogel by using polystyrene colloidal particles as sacrificial template and graphene oxide as a reinforcing filler. Owing to the excellent metal chelation ability of calcium alginate and controlled nanosized pore structure, the [...] Read more.

In this study, we fabricated a porous calcium alginate/graphene oxide composite aerogel by using polystyrene colloidal particles as sacrificial template and graphene oxide as a reinforcing filler. Owing to the excellent metal chelation ability of calcium alginate and controlled nanosized pore structure, the as-prepared calcium alginate/graphene oxide composite aerogel (mp-CA/GO) can reach the adsorption equilibrium in 40 min, and the maximum adsorption capacity for Pb²⁺, Cu²⁺ and Cd²⁺ is 368.2, 98.1 and 183.6 mg/g, respectively. This is higher than most of the reported heavy metal ion sorbents. Moreover, the mp-CA/GO can be regenerated through simple acid-washing and be used repeatedly with little loss in performance. The adsorption mechanism analysis indicates that the mp-CA/GO adsorb the heavy metal ions mainly through the ion exchange and chemical coordination effects. Full article

(This article belongs to the Special Issue Nanocomposites for Environmental and Energy Applications)

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14 pages, 4169 KiB

Open AccessArticle

Inhibition Effect of Graphene on Space Charge Injection and Accumulation in Low-Density Polyethylene

by Zhonglei Li, Jingang Su, Boxue Du, Zhaohao Hou and Chenlei Han

Nanomaterials 2018, 8(11), 956; https://doi.org/10.3390/nano8110956 - 20 Nov 2018

Cited by 16 | Viewed by 3367

Abstract

Space charge injection and accumulation is attracting much attention in the field of dielectric insulation especially for electronic devices, power equipment and so on. This paper proposes using the inhibition effect of graphene for the injection and accumulation of space charge in low-density [...] Read more.

Space charge injection and accumulation is attracting much attention in the field of dielectric insulation especially for electronic devices, power equipment and so on. This paper proposes using the inhibition effect of graphene for the injection and accumulation of space charge in low-density polyethylene (LDPE). Scanning electron microscope (SEM) and transmission electron microscopy (TEM) images were employed to observe the dispersion of graphene with a two-dimensional structure in LDPE. The time-dependent space charge dynamic behaviors of graphene/LDPE nanocomposites with the filler content of 0, 0.003, 0.005, 0.007 and 0.01 wt % were characterized by the pulsed electro-acoustic (PEA) test at 40, 60 and 80 °C, and the charge mobility was evaluated by its depolarization processes. The experimental results show that for the undoped LDPE film, large amounts of space charges were injected from the electrodes into samples, especially at 60 and 80 °C. The graphene/LDPE nanocomposites with a filler content of 0.005 wt % could markedly suppress the space charge injection and accumulation even at 80 °C, which is attributed to the large quantities of graphene-polymer in interface regions. These interface regions introduced numbers of deep trap sites within the forbidden band of nanocomposites, which can reduce the de-trapping rate of charges and suppress the space charge accumulation in the polymer bulks. The graphene/LDPE nanocomposites are suggested for dielectric applications, intending the inhibition of space charge injection and accumulation. Full article

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12 pages, 5343 KiB

Open AccessArticle

Enhanced Electrocatalytic Activity and Stability toward the Oxygen Reduction Reaction with Unprotected Pt Nanoclusters

by Jing Liu, Jiao Yin, Bo Feng, Tao Xu and Fu Wang

Nanomaterials 2018, 8(11), 955; https://doi.org/10.3390/nano8110955 - 20 Nov 2018

Cited by 12 | Viewed by 4081

Abstract

The Pt particles within diameters of 1–3 nm known as Pt nanoclusters (NCs) are widely considered to be satisfactory oxygen reduction reaction (ORR) catalysts due to higher electrocatalytic performance and cost effectiveness. However, the utilization of such smaller Pt NCs is always limited [...] Read more.

The Pt particles within diameters of 1–3 nm known as Pt nanoclusters (NCs) are widely considered to be satisfactory oxygen reduction reaction (ORR) catalysts due to higher electrocatalytic performance and cost effectiveness. However, the utilization of such smaller Pt NCs is always limited by the synthesis strategies, stability and methanol tolerance of Pt. Herein, unprotected Pt NCs (~2.2 nm) dispersed on carbon nanotubes (CNTs) were prepared via a modified top-down approach using liquid Li as a solvent to break down the bulk Pt. Compared with the commercial Pt/C, the resultant Pt NCs/CNTs catalyst (Pt loading: 10 wt.%) exhibited more desirable ORR catalytic performance in 0.1 M HClO₄. The specific activity (SA) and mass activity (MA) at 0.9 V for ORR over Pt NCs/CNTs were 2.5 and 3.2 times higher than those over the commercial Pt/C (Pt loading: 20 wt.%). Meanwhile, the Pt NCs/CNTs catalyst demonstrated more satisfactory stability and methanol tolerance. Compared with the obvious loss (~69%) of commercial Pt/C, only a slight current decrease (~10%) was observed for Pt NCs/CNTs after the chronoamperometric measurement for 2 × 10⁴ s. Hence, the as-prepared Pt NCs/CNTs material displays great potential as a practical ORR catalyst. Full article

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10 pages, 4160 KiB

Open AccessArticle

Growth and Self-Assembly of Silicon–Silicon Carbide Nanoparticles into Hybrid Worm-Like Nanostructures at the Silicon Wafer Surface

by Manuel Alejandro Perez-Guzman, Rebeca Ortega-Amaya, Yasuhiro Matsumoto, Andres Mauricio Espinoza-Rivas, Juan Morales-Corona, Jaime Santoyo-Salazar and Mauricio Ortega-Lopez

Nanomaterials 2018, 8(11), 954; https://doi.org/10.3390/nano8110954 - 20 Nov 2018

Cited by 4 | Viewed by 3966

Abstract

This work describes the growth of silicon–silicon carbide nanoparticles (Si–SiC) and their self-assembly into worm-like 1D hybrid nanostructures at the interface of graphene oxide/silicon wafer (GO/Si) under Ar atmosphere at 1000 °C. Depending on GO film thickness, spread silicon nanoparticles apparently develop on [...] Read more.

This work describes the growth of silicon–silicon carbide nanoparticles (Si–SiC) and their self-assembly into worm-like 1D hybrid nanostructures at the interface of graphene oxide/silicon wafer (GO/Si) under Ar atmosphere at 1000 °C. Depending on GO film thickness, spread silicon nanoparticles apparently develop on GO layers, or GO-embedded Si–SiC nanoparticles self-assembled into some-micrometers-long worm-like nanowires. It was found that the nanoarrays show that carbon–silicon-based nanowires (CSNW) are standing on the Si wafer. It was assumed that Si nanoparticles originated from melted Si at the Si wafer surface and GO-induced nucleation. Additionally, a mechanism for the formation of CSNW is proposed. Full article

(This article belongs to the Special Issue Silicon-Based Nanomaterials: Technology and Applications)

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16 pages, 3030 KiB

Open AccessArticle

A Raman Imaging Approach Using CD47 Antibody-Labeled SERS Nanoparticles for Identifying Breast Cancer and Its Potential to Guide Surgical Resection

by Ryan M. Davis, Jos L. Campbell, Sean Burkitt, Zhen Qiu, Soyoung Kang, Mana Mehraein, Dominie Miyasato, Helen Salinas, Jonathan T. C. Liu and Cristina Zavaleta

Nanomaterials 2018, 8(11), 953; https://doi.org/10.3390/nano8110953 - 20 Nov 2018

Cited by 45 | Viewed by 6087

Abstract

Raman spectroscopic imaging has shown great promise for improved cancer detection and localization with the use of tumor targeting surface enhanced Raman scattering (SERS) nanoparticles. With the ultrasensitive detection and multiplexing capabilities that SERS imaging has to offer, scientists have been investigating several [...] Read more.

Raman spectroscopic imaging has shown great promise for improved cancer detection and localization with the use of tumor targeting surface enhanced Raman scattering (SERS) nanoparticles. With the ultrasensitive detection and multiplexing capabilities that SERS imaging has to offer, scientists have been investigating several clinical applications that could benefit from this unique imaging strategy. Recently, there has been a push to develop new image-guidance tools for surgical resection to help surgeons sensitively and specifically identify tumor margins in real time. We hypothesized that SERS nanoparticles (NPs) topically applied to breast cancer resection margins have the potential to provide real-time feedback on the presence of residual cancer in the resection margins during lumpectomy. Here, we explore the ability of SERS nanoparticles conjugated with a cluster of differentiation-47 (CD47) antibody to target breast cancer. CD47 is a cell surface receptor that has recently been shown to be overexpressed on several solid tumor types. The binding potential of our CD47-labeled SERS nanoparticles was assessed using fluorescence assisted cell sorting (FACS) on seven different human breast cancer cell lines, some of which were triple negative (negative expression of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor-2 (HER2)). Xenograft mouse models were also used to assess the ability of our Raman imaging system to identify tumor from normal tissue. A ratiometric imaging strategy was used to quantify specific vs. nonspecific probe binding, resulting in improved tumor-to-background ratios. FACS analysis showed that CD47-labeled SERS nanoparticles bound to seven different breast cancer cell lines at levels 12-fold to 70-fold higher than isotype control-labeled nanoparticles (p < 0.01), suggesting that our CD47-targeted nanoparticles actively bind to CD47 on breast cancer cells. In a mouse xenograft model of human breast cancer, topical application of CD47-targeted nanoparticles to excised normal and cancer tissue revealed increased binding of CD47-targeted nanoparticles on tumor relative to normal adjacent tissue. The findings of this study support further investigation and suggest that SERS nanoparticles topically applied to breast cancer could guide more complete surgical resection during lumpectomy. Full article

(This article belongs to the Special Issue Raman Imaging Methods for Nanomaterials and Bioapplications)

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16 pages, 9871 KiB

Open AccessArticle

pH-Sensitive Poly(β-amino ester)s Nanocarriers Facilitate the Inhibition of Drug Resistance in Breast Cancer Cells

by Mengxue Zhou, Xingcai Zhang, Jin Xie, Rongxiang Qi, Huiru Lu, Stefano Leporatti, Jun Chen and Yi Hu

Nanomaterials 2018, 8(11), 952; https://doi.org/10.3390/nano8110952 - 19 Nov 2018

Cited by 51 | Viewed by 6047

Abstract

Multidrug resistance (MDR) remains an unmet challenge in chemotherapy. Stimuli-responsive nanocarriers emerge as a promising tool to overcome MDR. Herein, pH-sensitive poly(β-amino ester)s polymers (PHP)-based micellar nanoparticles were synthesized for enhanced doxorubicin (DOX) delivery in drug resistant breast cancer MCF-7/ADR cells. DOX-loaded PHP [...] Read more.

Multidrug resistance (MDR) remains an unmet challenge in chemotherapy. Stimuli-responsive nanocarriers emerge as a promising tool to overcome MDR. Herein, pH-sensitive poly(β-amino ester)s polymers (PHP)-based micellar nanoparticles were synthesized for enhanced doxorubicin (DOX) delivery in drug resistant breast cancer MCF-7/ADR cells. DOX-loaded PHP micelles showed rapid cell-internalization and lysosomal escape in MCF-7/ADR cells. The cytotoxicity assays showed relatively higher cell inhibition of DOX-loaded PHP micelles than that of free DOX against MCF-7/ADR cells. Further mechanistic studies showed that PHP micelles were able to inhibit P-glycoprotein (P-gp) activity by lowering mitochondrial membrane potentials and ATP levels. These results suggested that the enhanced antitumor effect might be attributed to PHP-mediated lysosomal escape and drug efflux inhibition. Therefore, PHP would be a promising pH-responsive nanocarrier for enhanced intracellular drug delivery and overcoming MDR in cancer cells. Full article

(This article belongs to the Special Issue Biomedical Applications of Nanotechnology)

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13 pages, 5792 KiB

Open AccessArticle

Effect of Aminosilane Coupling Agents with Different Chain Lengths on Thermo-Mechanical Properties of Cross-Linked Epoxy Resin

by Yujing Tang, Chao Tang, Dong Hu and Yingang Gui

Nanomaterials 2018, 8(11), 951; https://doi.org/10.3390/nano8110951 - 19 Nov 2018

Cited by 32 | Viewed by 4293

Abstract

In this paper, a molecular dynamics simulation method was used to study the thermo-mechanical properties of cross-linked epoxy resins doped with nano silica particles that were grafted with 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and 3-[2-(2-aminoethylamino)ethylamino]-propyl-trimethoxysilane with different chain lengths. Firstly, a set of pure epoxy [...] Read more.

In this paper, a molecular dynamics simulation method was used to study the thermo-mechanical properties of cross-linked epoxy resins doped with nano silica particles that were grafted with 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and 3-[2-(2-aminoethylamino)ethylamino]-propyl-trimethoxysilane with different chain lengths. Firstly, a set of pure epoxy resin models, and four sets of SiO₂/EP composite models were established. Then, a reasonable structure was obtained through a series of optimizations using molecular dynamics calculations. Next, the mechanical properties, hydrogen bond statistics, glass transition temperature, free volume fraction, and chain spacing of the five models were studied comparatively. The results show that doped nano silica particles of surfaces grafted with 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and 3-[2-(2-aminoethylamino)ethylamino]-propyl-trimethoxysilane with different chain lengths enhanced mechanical properties such as elastic modulus, shear modulus, and volume modulus obviously. The glass transition temperature increased by 15–16 K, 40–41 K, and 24–27 K, respectively. Finally, the data show that the cross-linked epoxy resin modified by nanoparticles grafted with N-(2-aminoethyl)-3-aminopropyl trimethoxysilane had better effects for improving thermo-mechanical properties by the comparatively studying the five groups of parameter models under the same conditions. Full article

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18 pages, 5963 KiB

Open AccessArticle

Peculiarities of Synthesis and Properties of Lignin–Silica Nanocomposites Prepared by Sol-Gel Method

by Tetyana M. Budnyak, Selda Aminzadeh, Ievgen V. Pylypchuk, Anastasia V. Riazanova, Valentin A. Tertykh, Mikael E. Lindström and Olena Sevastyanova

Nanomaterials 2018, 8(11), 950; https://doi.org/10.3390/nano8110950 - 18 Nov 2018

Cited by 35 | Viewed by 7469

Abstract

The development of advanced hybrid materials based on polymers from biorenewable sources and mineral nanoparticles is currently of high importance. In this paper, we applied softwood kraft lignins for the synthesis of lignin/SiO₂ nanostructured composites. We described the peculiarities of composites formation [...] Read more.

The development of advanced hybrid materials based on polymers from biorenewable sources and mineral nanoparticles is currently of high importance. In this paper, we applied softwood kraft lignins for the synthesis of lignin/SiO₂ nanostructured composites. We described the peculiarities of composites formation in the sol-gel process through the incorporation of the lignin into a silica network during the hydrolysis of tetraethoxysilane (TEOS). The initial activation of lignins was achieved by means of a Mannich reaction with 3-aminopropyltriethoxysilane (APTES). In the study, we present a detailed investigation of the physicochemical characteristics of initial kraft lignins and modified lignins on each step of the synthesis. Thus, 2D-NMR, ³¹P-NMR, size-exclusion chromatography (SEC) and dynamic light scattering (DLS) were applied to analyze the characteristics of pristine lignins and lignins in dioxan:water solutions. X-Ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) were used to confirm the formation of the lignin–silica network and characterize the surface and bulk structures of the obtained hybrids. Termogravimetric analysis (TGA) in nitrogen and air atmosphere were applied to a detailed investigation of the thermal properties of pristine lignins and lignins on each step of modification. SEM confirmed the nanostructure of the obtained composites. As was demonstrated, the activation of lignin is crucial for the sol-gel formation of a silica network in order to create novel hybrid materials from lignins and alkoxysilanes (e.g., TEOS). It was concluded that the structure of the lignin had an impact on its reactivity during the activation reaction, and consequently affected the properties of the final hybrid materials. Full article

(This article belongs to the Special Issue Synthesis, Characterization, and Applications of Polymer Nanocomposites)

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20 pages, 3572 KiB

Open AccessReview

Nanostructure Optimization of Platinum-Based Nanomaterials for Catalytic Applications

by Sibin Duan, Zhe Du, Hongsheng Fan and Rongming Wang

Nanomaterials 2018, 8(11), 949; https://doi.org/10.3390/nano8110949 - 17 Nov 2018

Cited by 39 | Viewed by 6725

Abstract

Platinum-based nanomaterials have attracted much interest for their promising potentials in fields of energy-related and environmental catalysis. Designing and controlling the surface/interface structure of platinum-based nanomaterials at the atomic scale and understanding the structure-property relationship have great significance for optimizing the performances in [...] Read more.

Platinum-based nanomaterials have attracted much interest for their promising potentials in fields of energy-related and environmental catalysis. Designing and controlling the surface/interface structure of platinum-based nanomaterials at the atomic scale and understanding the structure-property relationship have great significance for optimizing the performances in practical catalytic applications. In this review, the strategies to obtain platinum-based catalysts with fantastic activity and great stability by composition regulation, shape control, three-dimension structure construction, and anchoring onto supports, are presented in detail. Moreover, the structure-property relationship of platinum-based nanomaterials are also exhibited, and a brief outlook are given on the challenges and possible solutions in future development of platinum-based nanomaterials towards catalytic reactions. Full article

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11 pages, 4126 KiB

Open AccessArticle

In-Situ Preparation of CdTe Quantum Dots Capped with a β-Cyclodextrin-Epichlorohydrin Polymer: Polymer Influence on the Nanocrystal’s Optical Properties

by Rudy Martin-Trasanco, Hilda E. Esparza-Ponce, Pedro D. Ortiz, Diego P. Oyarzun, Cesar Zuñiga, Maria E. Montero-Cabrera, Alain Tundidor-Camba, Guadalupe del C. Pizarro and Ramiro Arratia-Pérez

Nanomaterials 2018, 8(11), 948; https://doi.org/10.3390/nano8110948 - 17 Nov 2018

Cited by 3 | Viewed by 3352

Abstract

β-Cyclodextrin (βCD), the less water soluble of the cyclodextrins, has been used as a capping agent in the preparation of semiconductor nanocrystals or quantum dots (QDs). Nevertheless, no reports have been found in the use of the highly water-soluble polymer of this, prepared [...] Read more.

β-Cyclodextrin (βCD), the less water soluble of the cyclodextrins, has been used as a capping agent in the preparation of semiconductor nanocrystals or quantum dots (QDs). Nevertheless, no reports have been found in the use of the highly water-soluble polymer of this, prepared by the crosslinking of the βCD units with epichlorohydrin in basic medium (βCDP). This polymer, besides to overcome the low solubility of the βCD, increases the inclusion constant of the guest; two parameters that deserve its use as capping agent, instead of the native cyclodextrin. In the present manuscript, we afforded the in-situ aqueous preparation of cadmium telluride (CdTe) QDs capped with βCDP. The polymer influence on the photoluminescent properties of the nanocrystals was analyzed. The βCDP controls the nanocrystals growth during the Oswald ripening stage. Consequently, the CdTe capped βCDP QDs showed lower Stokes-shift values, higher photoluminescent efficiency, and narrower size distribution than for nanocrystals obtained in the absence of polymer. Transmission electron microscopy (TEM) micrographs and energy dispersive X-ray spectroscopy (EDS) analysis revealed the composition and crystallinity of the CdTe QDs. This βCDP capped CdTe QDs is a potential scaffold for the supramolecular modification of QDs surface. Full article

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16 pages, 16662 KiB

Open AccessArticle

Advancing the Use of High-Performance Graphene-Based Multimodal Polymer Nanocomposite at Scale

by Ibrahim A. Ahmad, Krzysztof K. K. Koziol, Suleyman Deveci, Hyun-Kyung Kim and Ramachandran Vasant Kumar

Nanomaterials 2018, 8(11), 947; https://doi.org/10.3390/nano8110947 - 17 Nov 2018

Cited by 8 | Viewed by 5876

Abstract

The production of an innovative, high-performance graphene-based polymer nanocomposite using cost-effective techniques was pursued in this study. Well-dispersed and uniformly distributed graphene platelets within a polymer matrix, with strong interfacial bonding between the platelets and the matrix, provided an optimal nanocomposite system for [...] Read more.

The production of an innovative, high-performance graphene-based polymer nanocomposite using cost-effective techniques was pursued in this study. Well-dispersed and uniformly distributed graphene platelets within a polymer matrix, with strong interfacial bonding between the platelets and the matrix, provided an optimal nanocomposite system for industrial interest. This study reports on the reinforcement of high molecular weight multimodal-high-density polyethylene reinforced by a microwave-induced plasma graphene, using melt intercalation. The tailored process included designing a suitable screw configuration, paired with coordinating extruder conditions and blending techniques. This enabled the polymer to sufficiently degrade, predominantly through thermomechanical-degradation, as well as thermo-oxidative degradation, which subsequently created a suitable medium for the graphene sheets to disperse readily and distribute evenly within the polymer matrix. Different microscopy techniques were employed to prove the effectiveness. This was then qualitatively assessed by Raman spectroscopy, X-ray diffraction, rheology, mechanical testing, density measurements, thermal expansion, and thermogravimetric analysis, confirming both the originality as well as the effectiveness of the process. Full article

(This article belongs to the Special Issue Nanocellulose and Nanocarbons Based Hybrid Materials: Synthesis, Characterization and Applications)

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14 pages, 2967 KiB

Open AccessArticle

Green Synthesis of Ag Nanoparticles Using Grape Stalk Waste Extract for the Modification of Screen-Printed Electrodes

by Julio Bastos-Arrieta, Antonio Florido, Clara Pérez-Ràfols, Núria Serrano, Núria Fiol, Jordi Poch and Isabel Villaescusa

Nanomaterials 2018, 8(11), 946; https://doi.org/10.3390/nano8110946 - 17 Nov 2018

Cited by 54 | Viewed by 5925

Abstract

The chemical synthesis of silver nanoparticles (Ag-NPs) by using an environmentally friendly methodology for their preparation is presented. Thus, considering that plants possess components that can act as reducing agents and stabilizers in nanoparticles’ production, the synthesis of Ag-NPs by using an extract [...] Read more.

The chemical synthesis of silver nanoparticles (Ag-NPs) by using an environmentally friendly methodology for their preparation is presented. Thus, considering that plants possess components that can act as reducing agents and stabilizers in nanoparticles’ production, the synthesis of Ag-NPs by using an extract aqueous solution of grape stalk waste as a reducing and capping agent is studied. First, the total polyphenols and reducing sugars contained in the produced extracts at different conditions are characterized. After that, Ag-NPs are synthesized regarding the interaction of Ag ions (from silver nitrate) and the grape stalk extract. The effect of temperature, contact time, extract/metal solution volume ratio and pH solution in the synthesis of metal nanoparticles are also studied. Different sets of nanoparticle samples are characterized by means of Electron Microscopy coupled with Energy Dispersive X-Ray for qualitative chemical identification. Ag-NPs with an average diameter of 27.7 ± 0.6 nm are selected to proof their suitability for sensing purposes. Finally, screen-printed electrodes modified with Ag-NPs are tested for the simultaneous stripping voltammetric determination of Pb(II) and Cd(II). Results indicate good reproducibility, sensitivity and limits of detection around 2.7 µg L⁻¹ for both metal ions. Full article

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56 pages, 8341 KiB

Open AccessFeature PaperReview

Nanocarbon Reinforced Rubber Nanocomposites: Detailed Insights about Mechanical, Dynamical Mechanical Properties, Payne, and Mullin Effects

by Suneel Kumar Srivastava and Yogendra Kumar Mishra

Nanomaterials 2018, 8(11), 945; https://doi.org/10.3390/nano8110945 - 16 Nov 2018

Cited by 78 | Viewed by 11209

Abstract

The reinforcing ability of the fillers results in significant improvements in properties of polymer matrix at extremely low filler loadings as compared to conventional fillers. In view of this, the present review article describes the different methods used in preparation of different rubber [...] Read more.

The reinforcing ability of the fillers results in significant improvements in properties of polymer matrix at extremely low filler loadings as compared to conventional fillers. In view of this, the present review article describes the different methods used in preparation of different rubber nanocomposites reinforced with nanodimensional individual carbonaceous fillers, such as graphene, expanded graphite, single walled carbon nanotubes, multiwalled carbon nanotubes and graphite oxide, graphene oxide, and hybrid fillers consisting combination of individual fillers. This is followed by review of mechanical properties (tensile strength, elongation at break, Young modulus, and fracture toughness) and dynamic mechanical properties (glass transition temperature, crystallization temperature, melting point) of these rubber nanocomposites. Finally, Payne and Mullin effects have also been reviewed in rubber filled with different carbon based nanofillers. Full article

(This article belongs to the Special Issue Hybrid Nanomaterials for Future Technologies)

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20 pages, 1505 KiB

Open AccessReview

Biomedical Applications of Graphene-Based Structures

by Krzysztof Tadyszak, Jacek K. Wychowaniec and Jagoda Litowczenko

Nanomaterials 2018, 8(11), 944; https://doi.org/10.3390/nano8110944 - 16 Nov 2018

Cited by 190 | Viewed by 13948

Abstract

Graphene and graphene oxide (GO) structures and their reduced forms, e.g., GO paper and partially or fully reduced three-dimensional (3D) aerogels, are at the forefront of materials design for extensive biomedical applications that allow for the proliferation and differentiation/maturation of cells, drug delivery, [...] Read more.

Graphene and graphene oxide (GO) structures and their reduced forms, e.g., GO paper and partially or fully reduced three-dimensional (3D) aerogels, are at the forefront of materials design for extensive biomedical applications that allow for the proliferation and differentiation/maturation of cells, drug delivery, and anticancer therapies. Various viability tests that have been conducted in vitro on human cells and in vivo on mice reveal very promising results, which make graphene-based materials suitable for real-life applications. In this review, we will give an overview of the latest studies that utilize graphene-based structures and their composites in biological applications and show how the biomimetic behavior of these materials can be a step forward in bridging the gap between nature and synthetically designed graphene-based nanomaterials. Full article

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

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12 pages, 3291 KiB

Open AccessArticle

Application of Glycation in Regulating the Heat-Induced Nanoparticles of Egg White Protein

by Chenying Wang, Xidong Ren, Yujie Su and Yanjun Yang

Nanomaterials 2018, 8(11), 943; https://doi.org/10.3390/nano8110943 - 15 Nov 2018

Cited by 21 | Viewed by 3973

Abstract

Due to the poor thermal stability of egg white protein (EWP), important challenges remain regarding preparation of nanoparticles for EWP above the denaturation temperature at neutral conditions. In this study, nanoparticles were fabricated from conjugates of EWP and isomalto-oligosaccharide (IMO) after heating at [...] Read more.

Due to the poor thermal stability of egg white protein (EWP), important challenges remain regarding preparation of nanoparticles for EWP above the denaturation temperature at neutral conditions. In this study, nanoparticles were fabricated from conjugates of EWP and isomalto-oligosaccharide (IMO) after heating at 90 °C for 30 min. Meanwhile, the effects of protein concentration, temperature, pH, ionic strength and degree of glycation (DG) on the formation of nanoparticles from IMO-EWP were investigated. To further reveal the formation mechanism of the nanoparticles, structures, thermal denaturation properties and surface properties were compared between EWP and IMO-EWP conjugates. Furthermore, the emulsifying activity index (EAI) and the emulsifying stability index (ESI) of nanoparticles were determined. The results indicated that glycation enhanced thermal stability and net surface charge of EWP due to changes in the EWP structure. The thermal aggregation of EWP was inhibited significantly by glycation, and enhanced with a higher degree of glycation. Meanwhile, the nanoparticles (<200 nm in size) were obtained at pH 3.0, 7.0 and 9.0 in the presence of NaCl. The increased thermal stability and surface net negative charge after glycation contributed to the inhibition. The EAI and ESI of nanoparticles were increased nearly 3-fold and 2-fold respectively, as compared to unheated EWP. Full article

(This article belongs to the Special Issue Advances in Nanoparticles: Synthesis, Characterization, Theoretical Modelling, and Applications)

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32 pages, 19356 KiB

Open AccessReview

Liquid-Phase Exfoliation of Graphene: An Overview on Exfoliation Media, Techniques, and Challenges

by Yanyan Xu, Huizhe Cao, Yanqin Xue, Biao Li and Weihua Cai

Nanomaterials 2018, 8(11), 942; https://doi.org/10.3390/nano8110942 - 15 Nov 2018

Cited by 284 | Viewed by 25611

Abstract

Graphene, a two-dimensional (2D) carbon nanomaterial, has attracted worldwide attention owing to its fascinating properties. One of critical bottlenecks on some important classes of applications, such as printed electronics, conductive coatings, and composite fillers, is the lack of industrial-scale methods to produce high-quality [...] Read more.

Graphene, a two-dimensional (2D) carbon nanomaterial, has attracted worldwide attention owing to its fascinating properties. One of critical bottlenecks on some important classes of applications, such as printed electronics, conductive coatings, and composite fillers, is the lack of industrial-scale methods to produce high-quality graphene in the form of liquid suspensions, inks, or dispersions. Since 2008, when liquid-phase exfoliation (LPE) of graphene via sonication was initiated, huge progress has been made in the past decade. This review highlights the latest progress on the successful preparation of graphene in various media, including organic solvents, ionic liquids, water/polymer or surfactant solutions, and some other green dispersants. The techniques of LPE, namely sonication, high-shear mixing, and microfluidization are reviewed subsequently. Moreover, several typical devices of high-shear mixing and exfoliation mechanisms are introduced in detail. Finally, we give perspectives on future research directions for the development of green exfoliation media and efficient techniques for producing high-quality graphene. This systematic exploratory study of LPE will potentially pave the way for the scalable production of graphene, which can be also applied to produce other 2D layered materials, such as BN, MoS₂, WS₂, etc. Full article

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10 pages, 2408 KiB

Open AccessCommunication

Preparation of Hydrogen Peroxide Sensitive Nanofilms by a Layer-by-Layer Technique

by Kentaro Yoshida, Tetsuya Ono, Takenori Dairaku, Yoshitomo Kashiwagi and Katsuhiko Sato

Nanomaterials 2018, 8(11), 941; https://doi.org/10.3390/nano8110941 - 15 Nov 2018

Cited by 4 | Viewed by 3088

Abstract

H₂O₂-sensitive nanofilms composed of DNA and hemin-appended poly(ethyleneimine) (H-PEI) were prepared by a layer-by-layer deposition of DNA and H-PEI through an electrostatic interaction. The (H-PEI/DNA)₅ film was decomposed by addition of 10 mM H₂O₂. [...] Read more.

H₂O₂-sensitive nanofilms composed of DNA and hemin-appended poly(ethyleneimine) (H-PEI) were prepared by a layer-by-layer deposition of DNA and H-PEI through an electrostatic interaction. The (H-PEI/DNA)₅ film was decomposed by addition of 10 mM H₂O₂. H₂O₂-induced decomposition was also confirmed in the hemin-containing (PEI/DNA)₅ in which hemin molecules were adsorbed by a noncovalent bond to the nanofilm. On the other hand, the (PEI/DNA)₅ film containing no hemin and the (H-PEI/PSS)₅ film using PSS instead of DNA did not decompose even with 100 mM H₂O₂. The mechanism of nanofilm decomposition was thought that more reactive oxygen species (ROS) was formed by reaction of hemin and H₂O₂ and then the ROS caused DNA cleavage. As a result (H-PEI/DNA)₅ and hemin-containing (PEI/DNA)₅ films were decomposed. The decomposition rate of these nanofilms were depended on concentration of H₂O₂, modification ratio of hemin, pH, and ionic strength. Full article

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20 pages, 7967 KiB

Open AccessFeature PaperArticle

The Effect of Boron Nitride on the Thermal and Mechanical Properties of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

by Mualla Öner, Gülnur Kızıl, Gülşah Keskin, Celine Pochat-Bohatier and Mikhael Bechelany

Nanomaterials 2018, 8(11), 940; https://doi.org/10.3390/nano8110940 - 15 Nov 2018

Cited by 32 | Viewed by 5164

Abstract

The thermal and mechanical properties of poly(3-hydroxybutyrate-co-3-hydroxyvalerate, PHBV) composites filled with boron nitride (BN) particles with two different sizes and shapes were studied by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), thermal gravimetric analysis [...] Read more.

The thermal and mechanical properties of poly(3-hydroxybutyrate-co-3-hydroxyvalerate, PHBV) composites filled with boron nitride (BN) particles with two different sizes and shapes were studied by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), thermal gravimetric analysis (TGA) and mechanical testing. The biocomposites were produced by melt extrusion of PHBV with untreated BN and surface-treated BN particles. Thermogravimetric analysis (TGA) showed that the thermal stability of the composites was higher than that of neat PHBV while the effect of the different shapes and sizes of the particles on the thermal stability was insignificant. DSC analysis showed that the crystallinity of the PHBV was not affected significantly by the change in filler concentration and the type of the BN nanoparticle but decreasing of the crystallinity of PHBV/BN composites was observed at higher loadings. BN particles treated with silane coupling agent yielded nanocomposites characterized by good mechanical performance. The results demonstrate that mechanical properties of the composites were found to increase more for the silanized flake type BN (OSFBN) compared to silanized hexagonal disk type BN (OSBN). The highest Young’s modulus was obtained for the nanocomposite sample containing 1 wt.% OSFBN, for which increase of Young’s modulus up to 19% was observed in comparison to the neat PHBV. The Halpin–Tsai and Hui–Shia models were used to evaluate the effect of reinforcement by BN particles on the elastic modulus of the composites. Micromechanical models for initial composite stiffness showed good correlation with experimental values. Full article

(This article belongs to the Special Issue Boron Nitride Nanostructures)

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23 pages, 1842 KiB

Open AccessReview

An Overview of the Synthesis of Gold Nanoparticles Using Radiation Technologies

by Lucas Freitas de Freitas, Gustavo Henrique Costa Varca, Jorge Gabriel Dos Santos Batista and Ademar Benévolo Lugão

Nanomaterials 2018, 8(11), 939; https://doi.org/10.3390/nano8110939 - 15 Nov 2018

Cited by 153 | Viewed by 24990

Abstract

At a nano-level, optical properties of gold are unique and gave birth to an emerging platform of nanogold-based systems for diverse applications, because gold nanoparticle properties are tunable as a function of size and shape. Within the available techniques for the synthesis of [...] Read more.

At a nano-level, optical properties of gold are unique and gave birth to an emerging platform of nanogold-based systems for diverse applications, because gold nanoparticle properties are tunable as a function of size and shape. Within the available techniques for the synthesis of gold nanoparticles, the radiolytic synthesis allows proper control of the nucleation process without the need for reducing agents, in a single step, combined or not with simultaneous sterilization. This review details and summarizes the use of radiation technologies for the synthesis and preparation of gold nanoparticles concerning fundamental aspects, mechanism, current pathways for synthesis and radiation sources, as well as briefly outlines final applications and some toxicity aspects related to nanogold-based systems. Full article

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8 pages, 3820 KiB

Open AccessArticle

Dielectric Metasurface-Based High-Efficiency Mid-Infrared Optical Filter

by Fei Shen, Qianlong Kang, Jingjing Wang, Kai Guo, Qingfeng Zhou and Zhongyi Guo

Nanomaterials 2018, 8(11), 938; https://doi.org/10.3390/nano8110938 - 14 Nov 2018

Cited by 40 | Viewed by 8670

Abstract

Dielectric nanoresonantors may generate both electric and magnetic Mie resonances with low optical loss, thereby offering highly efficient paths for obtaining integrated optical devices. In this paper, we propose and design an optical filter with a high working efficiency in the mid-infrared (mid-IR) [...] Read more.

Dielectric nanoresonantors may generate both electric and magnetic Mie resonances with low optical loss, thereby offering highly efficient paths for obtaining integrated optical devices. In this paper, we propose and design an optical filter with a high working efficiency in the mid-infrared (mid-IR) range, based on an all-dielectric metasurface composed of silicon (Si) nanodisk arrays. We numerically demonstrate that, by increasing the diameter of the Si nanodisk, the range of the proposed reflective optical filter could effectively cover a wide range of operation wavelengths, from 3.8 μm to 4.7 μm, with the reflection efficiencies reaching to almost 100%. The electromagnetic eigen-mode decomposition of the silicon nanodisk shows that the proposed optical filter is based on the excitation of the electric dipole resonance. In addition, we demonstrate that the proposed filter has other important advantages of polarization-independence and incident-angle independence, ranging from 0° to 20° at the resonance dip, which can be used in a broad range of applications, such as sensing, imaging, and energy harvesting. Full article

(This article belongs to the Special Issue Dielectric Nanophotonics and Their Applications)

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15 pages, 9340 KiB

Open AccessArticle

Highly Efficient Red Cabbage Anthocyanin Inserted TiO₂ Aerogel Nanocomposites for Photocatalytic Reduction of Cr(VI) under Visible Light

by Haiyan Yang, Liang Jiang, Yizhou Li, Guoqing Li, Yepeng Yang, Jiao He, Jiaqiang Wang and Zhiying Yan

Nanomaterials 2018, 8(11), 937; https://doi.org/10.3390/nano8110937 - 14 Nov 2018

Cited by 14 | Viewed by 3884

Abstract

In sharp contrast to conventional photosensitization methods in which the organic pigments were often adsorbed, herein we present a study on natural vegetable pigment inserted TiO₂ aerogel nanocomposites and we directly use red cabbage anthocyanin (RCP) as a structure-directing agent. It was [...] Read more.

In sharp contrast to conventional photosensitization methods in which the organic pigments were often adsorbed, herein we present a study on natural vegetable pigment inserted TiO₂ aerogel nanocomposites and we directly use red cabbage anthocyanin (RCP) as a structure-directing agent. It was found that pure TiO₂ aerogel nanocomposite did not exhibit any meaningful activity for photocatalytic reduction of Cr(VI). However, the photocatalytic reduction activity was greatly improved by the RCP inserted TiO₂ aerogel nanocomposites under visible-light irradiation, which was approximately 2- and 12.3-fold higher than that of TiO₂ aerogel conventionally photosensitized by RCP and pure TiO₂ aerogel nanocomposites, respectively. It also exhibited good stability and could be reused at least three times without losing a significant amount of its activity. Full article

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8 pages, 2867 KiB

Open AccessArticle

Structural and Fluorine Plasma Etching Behavior of Sputter-Deposition Yttrium Fluoride Film

by Wei-Kai Wang, Yu-Xiu Lin and Yi-Jie Xu

Nanomaterials 2018, 8(11), 936; https://doi.org/10.3390/nano8110936 - 14 Nov 2018

Cited by 19 | Viewed by 5801

Abstract

Yttrium fluoride (YF₃) films were grown on sapphire substrate by a radio frequency magnetron using a commercial ceramic target in a vacuum chamber. The structure, composition, and plasma etching behavior of the films were systematically investigated. The YF₃ film was [...] Read more.

Yttrium fluoride (YF₃) films were grown on sapphire substrate by a radio frequency magnetron using a commercial ceramic target in a vacuum chamber. The structure, composition, and plasma etching behavior of the films were systematically investigated. The YF₃ film was deposited at a working pressure of 5 mTorr and an RF power of 150 W. The substrate-heating temperature was increased from 400 to 700 °C in increments of 100 °C. High-resolution transmission electron microscopy (HRTEM) and X-ray diffraction results confirmed an orthorhombic YF₃ structure was obtained at a substrate temperature of 700 °C for 2 h. X-ray photoelectron spectroscopy revealed a strongly fluorinated bond (Y–F bond) on the etched surface of the YF₃ films. HRTEM analysis also revealed that the YF₃ films became yttrium-oxyfluorinated after exposure to fluorocarbon plasma. The etching depth was three times lower on YF₃ film than on Al₂O₃ plate. These results showed that the YF₃ films have excellent erosion resistance properties compared to Al₂O₃ plates. Full article

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32 pages, 6164 KiB

Open AccessReview

Thermo-Sensitive Nanomaterials: Recent Advance in Synthesis and Biomedical Applications

by Paola Sánchez-Moreno, Juan De Vicente, Stefania Nardecchia, Juan A. Marchal and Houria Boulaiz

Nanomaterials 2018, 8(11), 935; https://doi.org/10.3390/nano8110935 - 13 Nov 2018

Cited by 95 | Viewed by 9280

Abstract

Progress in nanotechnology has enabled us to open many new fronts in biomedical research by exploiting the peculiar properties of materials at the nanoscale. The thermal sensitivity of certain materials is a highly valuable property because it can be exploited in many promising [...] Read more.

Progress in nanotechnology has enabled us to open many new fronts in biomedical research by exploiting the peculiar properties of materials at the nanoscale. The thermal sensitivity of certain materials is a highly valuable property because it can be exploited in many promising applications, such as thermo-sensitive drug or gene delivery systems, thermotherapy, thermal biosensors, imaging, and diagnosis. This review focuses on recent advances in thermo-sensitive nanomaterials of interest in biomedical applications. We provide an overview of the different kinds of thermoresponsive nanomaterials, discussing their potential and the physical mechanisms behind their thermal response. We thoroughly review their applications in biomedicine and finally discuss the current challenges and future perspectives of thermal therapies. Full article

(This article belongs to the Special Issue Nanomaterials for Photothermal/Photodynamic Therapy)

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15 pages, 7242 KiB

Open AccessArticle

Synthesis of Reduced Graphene Oxide/Titanium Dioxide Nanotubes (rGO/TNT) Composites as an Electrical Double Layer Capacitor

by John Paolo L. Lazarte, Regine Clarisse Dipasupil, Gweneth Ysabelle S. Pasco, Ramon Christian P. Eusebio, Aileen H. Orbecido, Ruey-an Doong and Liza Bautista-Patacsil

Nanomaterials 2018, 8(11), 934; https://doi.org/10.3390/nano8110934 - 9 Nov 2018

Cited by 35 | Viewed by 8143

Abstract

Composites of synthesized reduced graphene oxide (rGO) and titanium dioxide nanotubes (TNTs) were examined and combined at different mass proportions (3:1, 1:1, and 1:3) to develop an electrochemical double layer capacitor (EDLC) nanocomposite. Three different combination methods of synthesis—(1) TNT introduction during GO [...] Read more.

Composites of synthesized reduced graphene oxide (rGO) and titanium dioxide nanotubes (TNTs) were examined and combined at different mass proportions (3:1, 1:1, and 1:3) to develop an electrochemical double layer capacitor (EDLC) nanocomposite. Three different combination methods of synthesis—(1) TNT introduction during GO reduction, (2) rGO introduction during TNT formation, and (3) TNT introduction in rGO sheets using a microwave reactor—were used to produce nanocomposites. Among the three methods, method 3 yielded an EDLC nanomaterial with a highly rectangular cyclic voltammogram and steep electrochemical impedance spectroscopy plot. The specific capacitance for method 3 nanocomposites ranged from 47.26–165.22 F/g while that for methods 1 and 2 nanocomposites only ranged from 14.03–73.62 F/g and 41.93–84.36 F/g, respectively. Furthermore, in all combinations used, the 3:1 graphene/titanium dioxide-based samples consistently yielded the highest specific capacitance. The highest among these nanocomposites is 3:1 rGO/TNT. Characterization of this highly capacitive 3:1 rGO/TNT EDLC composite revealed the dominant presence of partially amorphous rGO as seen in its XRD and SEM with branching crystalline anatase TNTs as seen in its XRD and TEM. Such property showed great potential that is desirable for applications to capacitive deionization and energy storage. Full article

(This article belongs to the Special Issue Graphite, Graphene, Advanced Carbon Materials and Nanostructured Carbon-Based Composites and Selected Papers from Carbon 2018)

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20 pages, 7936 KiB

Open AccessArticle

Multifunctional Platform Based on Electroactive Polymers and Silica Nanoparticles for Tissue Engineering Applications

by Sylvie Ribeiro, Tânia Ribeiro, Clarisse Ribeiro, Daniela M. Correia, José P. Sequeira Farinha, Andreia Castro Gomes, Carlos Baleizão and Senentxu Lanceros-Méndez

Nanomaterials 2018, 8(11), 933; https://doi.org/10.3390/nano8110933 - 9 Nov 2018

Cited by 15 | Viewed by 4097

Abstract

Poly(vinylidene fluoride) nanocomposites processed with different morphologies, such as porous and non-porous films and fibres, have been prepared with silica nanoparticles (SiNPs) of varying diameter (17, 100, 160 and 300 nm), which in turn have encapsulated perylenediimide (PDI), a fluorescent molecule. The structural, [...] Read more.

Poly(vinylidene fluoride) nanocomposites processed with different morphologies, such as porous and non-porous films and fibres, have been prepared with silica nanoparticles (SiNPs) of varying diameter (17, 100, 160 and 300 nm), which in turn have encapsulated perylenediimide (PDI), a fluorescent molecule. The structural, morphological, optical, thermal, and mechanical properties of the nanocomposites, with SiNP filler concentration up to 16 wt %, were evaluated. Furthermore, cytotoxicity and cell proliferation studies were performed. All SiNPs are negatively charged independently of the pH and more stable from pH 5 upwards. The introduction of SiNPs within the polymer matrix increases the contact angle independently of the nanoparticle diameter. Moreover, the smallest ones (17 nm) also improve the PVDF Young’s modulus. The filler diameter, physico-chemical, thermal and mechanical properties of the polymer matrix were not significantly affected. Finally, the SiNPs’ inclusion does not induce cytotoxicity in murine myoblasts (C2C12) after 72 h of contact and proliferation studies reveal that the prepared composites represent a suitable platform for tissue engineering applications, as they allow us to combine the biocompatibility and piezoelectricity of the polymer with the possible functionalization and drug encapsulation and release of the SiNP. Full article

(This article belongs to the Special Issue Nanocomposites of Polymers and Inorganic Nanoparticles)

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