Nanomaterials

17 pages, 8707 KiB

Open AccessArticle

Novel Antimicrobial Titanium Dioxide Nanotubes Obtained through a Combination of Atomic Layer Deposition and Electrospinning Technologies

by Carol López de Dicastillo, Cristian Patiño, María Jose Galotto, Juan Luis Palma, Daniela Alburquenque and Juan Escrig

Nanomaterials 2018, 8(2), 128; https://doi.org/10.3390/nano8020128 - 24 Feb 2018

Cited by 47 | Viewed by 6652

Abstract

The search for new antimicrobial substances has increased in recent years. Antimicrobial nanostructures are one of the most promising alternatives. In this work, titanium dioxide nanotubes were obtained by an atomic layer deposition (ALD) process over electrospun polyvinyl alcohol nanofibers (PVN) at different [...] Read more.

The search for new antimicrobial substances has increased in recent years. Antimicrobial nanostructures are one of the most promising alternatives. In this work, titanium dioxide nanotubes were obtained by an atomic layer deposition (ALD) process over electrospun polyvinyl alcohol nanofibers (PVN) at different temperatures with the purpose of obtaining antimicrobial nanostructures with a high specific area. Electrospinning and ALD parameters were studied in order to obtain PVN with smallest diameter and highest deposition rate, respectively. Chamber temperature was a key factor during ALD process and an appropriate titanium dioxide deposition performance was achieved at 200 °C. Subsequently, thermal and morphological analysis by SEM and TEM microscopies revealed hollow nanotubes were obtained after calcination process at 600 °C. This temperature allowed complete polymer removal and influenced the resulting anatase crystallographic structure of titanium dioxide that positively affected their antimicrobial activities. X-ray analysis confirmed the change of titanium dioxide crystallographic structure from amorphous phase of deposited PVN to anatase crystalline structure of nanotubes. These new nanostructures with very large surface areas resulted in interesting antimicrobial properties against Gram-positive and Gram-negative bacteria. Titanium dioxide nanotubes presented the highest activity against Escherichia coli with 5 log cycles reduction at 200 μg/mL concentration. Full article

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9 pages, 2948 KiB

Open AccessCommunication

Bioinspired Design of Alcohol Dehydrogenase@nano TiO₂ Microreactors for Sustainable Cycling of NAD⁺/NADH Coenzyme

by Sen Lin, Shiyong Sun, Ke Wang, Kexuan Shen, Biaobiao Ma, Yuquan Ren and Xiaoyu Fan

Nanomaterials 2018, 8(2), 127; https://doi.org/10.3390/nano8020127 - 24 Feb 2018

Cited by 34 | Viewed by 7734

Abstract

The bioinspired design and construction of enzyme@capsule microreactors with specific cell-like functionality has generated tremendous interest in recent years. Inspired by their fascinating complexity, scientists have endeavored to understand the essential aspects of a natural cell and create biomimicking microreactors so as to [...] Read more.

The bioinspired design and construction of enzyme@capsule microreactors with specific cell-like functionality has generated tremendous interest in recent years. Inspired by their fascinating complexity, scientists have endeavored to understand the essential aspects of a natural cell and create biomimicking microreactors so as to immobilize enzymes within the hierarchical structure of a microcapsule. In this study, simultaneous encapsulation of alcohol dehydrogenase (ADH) was achieved during the preparation of microcapsules by the Pickering emulsion method using amphiphilic modified TiO₂ nanoparticles (NPs) as building blocks for assembling the photocatalytic microcapsule membrane. The ADH@TiO₂ NP microreactors exhibited dual catalytic functions, i.e., spatially confined enzymatic catalysis and the membrane-associated photocatalytic oxidation under visible light. The sustainable cycling of nicotinamide adenine dinucleotide (NAD) coenzyme between NADH and NAD⁺ was realized by enzymatic regeneration of NADH from NAD⁺ reduction, and was provided in a form that enabled further photocatalytic oxidation to NAD⁺ under visible light. This bioinspired ADH@TiO₂ NP microreactor allowed the linking of a semiconductor mineral-based inorganic photosystem to enzymatic reactions. This is a first step toward the realization of sustainable biological cycling of NAD⁺/NADH coenzyme in synthetic functional microsystems operating under visible light irradiation. Full article

(This article belongs to the Special Issue Nanomaterials in Biocatalyst)

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18 pages, 2066 KiB

Open AccessArticle

Production of Curcumin-Loaded Silk Fibroin Nanoparticles for Cancer Therapy

by Mercedes G. Montalbán, Jeannine M. Coburn, A. Abel Lozano-Pérez, José L. Cenis, Gloria Víllora and David L. Kaplan

Nanomaterials 2018, 8(2), 126; https://doi.org/10.3390/nano8020126 - 24 Feb 2018

Cited by 149 | Viewed by 11640

Abstract

Curcumin, extracted from the rhizome of Curcuma longa, has been widely used in medicine for centuries due to its anti-inflammatory, anti-cancer, anti-oxidant and anti-microbial effects. However, its bioavailability during treatments is poor because of its low solubility in water, slow dissolution rate [...] Read more.

Curcumin, extracted from the rhizome of Curcuma longa, has been widely used in medicine for centuries due to its anti-inflammatory, anti-cancer, anti-oxidant and anti-microbial effects. However, its bioavailability during treatments is poor because of its low solubility in water, slow dissolution rate and rapid intestinal metabolism. For these reasons, improving the therapeutic efficiency of curcumin using nanocarriers (e.g., biopolymer nanoparticles) has been a research focus, to foster delivery of the curcumin inside cells due to their small size and large surface area. Silk fibroin from the Bombyx mori silkworm is a biopolymer characterized by its biocompatibility, biodegradability, amphiphilic chemistry, and excellent mechanical properties in various material formats. These features make silk fibroin nanoparticles useful vehicles for delivering therapeutic drugs, such as curcumin. Curcumin-loaded silk fibroin nanoparticles were synthesized using two procedures (physical adsorption and coprecipitation) more scalable than methods previously described using ionic liquids. The results showed that nanoparticle formulations were 155 to 170 nm in diameter with a zeta potential of approximately −45 mV. The curcumin-loaded silk fibroin nanoparticles obtained by both processing methods were cytotoxic to carcinogenic cells, while not decreasing viability of healthy cells. In the case of tumor cells, curcumin-loaded silk fibroin nanoparticles presented higher efficacy in cytotoxicity against neuroblastoma cells than hepatocarcinoma cells. In conclusion, curcumin-loaded silk fibroin nanoparticles constitute a biodegradable and biocompatible delivery system with the potential to treat tumors by local, long-term sustained drug delivery. Full article

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

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16 pages, 3919 KiB

Open AccessArticle

Effects of Graphene Oxide Nanoparticles on the Immune System Biomarkers Produced by RAW 264.7 and Human Whole Blood Cell Cultures

by Kim Lategan, Hend Alghadi, Mohamed Bayati, Maria Fidalgo De Cortalezzi and Edmund Pool

Nanomaterials 2018, 8(2), 125; https://doi.org/10.3390/nano8020125 - 24 Feb 2018

Cited by 48 | Viewed by 10281

Abstract

Graphene oxide nanoparticles (GONPs) have attracted a lot of attention due to their many applications. These applications include batteries, super capacitors, drug delivery and biosensing. However, few studies have investigated the effects of these nanoparticles on the immune system. In this study, the [...] Read more.

Graphene oxide nanoparticles (GONPs) have attracted a lot of attention due to their many applications. These applications include batteries, super capacitors, drug delivery and biosensing. However, few studies have investigated the effects of these nanoparticles on the immune system. In this study, the in vitro effects of GONPs on the immune system was evaluated by exposing murine macrophages, RAW 264.7 cells and human whole blood cell cultures (to GONPs. The effects of GONPs on RAW cells were monitored under basal conditions. The whole blood cell cultures were exposed to GONPs in the presence or absence of the mitogens lipopolysaccharide (LPS) and phytohaemmagglutinin (PHA). A number of parameters were monitored for both RAW and whole blood cell cultures, these included cytotoxicity, inflammatory biomarkers, cytokines of the acquired immune system and a proteome profile analysis. The GONPs were cytotoxic to both RAW and whole blood cell cultures at 500 μg/mL. In the absence of LPS, GONPs elicited an inflammatory response from the murine macrophage, RAW and whole blood cell cultures at 15.6 and 5 μg/mL respectively. This activation was further corroborated by proteome profile analysis of both experimental cultures. GONPs inhibited LPS induced interleukin 6 (IL-6) synthesis and PHA induced interferon gamma (IFNγ) synthesis by whole blood cell cultures in a dose dependent manner. In the absence of mitogens, GONPs stimulated IL-10 synthesis by whole blood cell cultures. The current study shows that GONPs modulate immune system biomarkers and that these may pose a health risk to individuals exposed to this type of nanoparticle. Full article

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16 pages, 7357 KiB

Open AccessArticle

Engineering of Corneal Tissue through an Aligned PVA/Collagen Composite Nanofibrous Electrospun Scaffold

by Zhengjie Wu, Bin Kong, Rui Liu, Wei Sun and Shengli Mi

Nanomaterials 2018, 8(2), 124; https://doi.org/10.3390/nano8020124 - 24 Feb 2018

Cited by 77 | Viewed by 8003

Abstract

Corneal diseases are the main reason of vision loss globally. Constructing a corneal equivalent which has a similar strength and transparency with the native cornea, seems to be a feasible way to solve the shortage of donated cornea. Electrospun collagen scaffolds are often [...] Read more.

Corneal diseases are the main reason of vision loss globally. Constructing a corneal equivalent which has a similar strength and transparency with the native cornea, seems to be a feasible way to solve the shortage of donated cornea. Electrospun collagen scaffolds are often fabricated and used as a tissue-engineered cornea, but the main drawback of poor mechanical properties make it unable to meet the requirement for surgery suture, which limits its clinical applications to a large extent. Aligned polyvinyl acetate (PVA)/collagen (PVA-COL) scaffolds were electrospun by mixing collagen and PVA to reinforce the mechanical strength of the collagen electrospun scaffold. Human keratocytes (HKs) and human corneal epithelial cells (HCECs) inoculated on aligned and random PVA-COL electrospun scaffolds adhered and proliferated well, and the aligned nanofibers induced orderly HK growth, indicating that the designed PVA-COL composite nanofibrous electrospun scaffold is suitable for application in tissue-engineered cornea. Full article

(This article belongs to the Special Issue Nanofibrous Scaffolds for Biomedical Application)

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14 pages, 5203 KiB

Open AccessArticle

Printed Graphene Derivative Circuits as Passive Electrical Filters

by Dogan Sinar and George K. Knopf

Nanomaterials 2018, 8(2), 123; https://doi.org/10.3390/nano8020123 - 23 Feb 2018

Cited by 9 | Viewed by 6328

Abstract

The objective of this study is to inkjet print resistor-capacitor (RC) low pass electrical filters, using a novel water-based cellulose graphene ink, and compare the voltage-frequency and transient behavior to equivalent circuits constructed from discrete passive components. The synthesized non-toxic graphene-carboxymethyl [...] Read more.

The objective of this study is to inkjet print resistor-capacitor (RC) low pass electrical filters, using a novel water-based cellulose graphene ink, and compare the voltage-frequency and transient behavior to equivalent circuits constructed from discrete passive components. The synthesized non-toxic graphene-carboxymethyl cellulose (G-CMC) ink is deposited on mechanically flexible polyimide substrates using a customized printer that dispenses functionalized aqueous solutions. The design of the printed first-order and second-order low-pass RC filters incorporate resistive traces and interdigitated capacitors. Low pass filter characteristics, such as time constant, cut-off frequency and roll-off rate, are determined for comparative analysis. Experiments demonstrate that for low frequency applications (<100 kHz) the printed graphene derivative circuits performed as well as the circuits constructed from discrete resistors and capacitors for both low pass filter and RC integrator applications. The impact of mechanical stress due to bending on the electrical performance of the flexible printed circuits is also investigated. Full article

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9 pages, 2506 KiB

Open AccessArticle

Dynamic Diffraction Studies on the Crystallization, Phase Transformation, and Activation Energies in Anodized Titania Nanotubes

by Hani Albetran, Victor Vega, Victor M. Prida and It-Meng Low

Nanomaterials 2018, 8(2), 122; https://doi.org/10.3390/nano8020122 - 23 Feb 2018

Cited by 12 | Viewed by 3877

Abstract

The influence of calcination time on the phase transformation and crystallization kinetics of anodized titania nanotube arrays was studied using in-situ isothermal and non-isothermal synchrotron radiation diffraction from room temperature to 900 °C. Anatase first crystallized at 400 °C, while rutile crystallized at [...] Read more.

The influence of calcination time on the phase transformation and crystallization kinetics of anodized titania nanotube arrays was studied using in-situ isothermal and non-isothermal synchrotron radiation diffraction from room temperature to 900 °C. Anatase first crystallized at 400 °C, while rutile crystallized at 550 °C. Isothermal heating of the anodized titania nanotubes by an increase in the calcination time at 400, 450, 500, 550, 600, and 650 °C resulted in a slight reduction in anatase abundance, but an increase in the abundance of rutile because of an anatase-to-rutile transformation. The Avrami equation was used to model the titania crystallization mechanism and the Arrhenius equation was used to estimate the activation energies of the titania phase transformation. Activation energies of 22 (10) kJ/mol for the titanium-to-anatase transformation, and 207 (17) kJ/mol for the anatase-to-rutile transformation were estimated. Full article

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16 pages, 3306 KiB

Open AccessArticle

Enhanced Antitumor Effects of Epidermal Growth Factor Receptor Targetable Cetuximab-Conjugated Polymeric Micelles for Photodynamic Therapy

by Ming-Hsiang Chang, Chin-Ling Pai, Ying-Chen Chen, Hsiu-Ping Yu, Chia-Yen Hsu and Ping-Shan Lai

Nanomaterials 2018, 8(2), 121; https://doi.org/10.3390/nano8020121 - 22 Feb 2018

Cited by 34 | Viewed by 5412

Abstract

Nanocarrier-based delivery systems are promising strategies for enhanced therapeutic efficacy and safety of toxic drugs. Photodynamic therapy (PDT)—a light-triggered chemical reaction that generates localized tissue damage for disease treatments—usually has side effects, and thus patients receiving photosensitizers should be kept away from direct [...] Read more.

Nanocarrier-based delivery systems are promising strategies for enhanced therapeutic efficacy and safety of toxic drugs. Photodynamic therapy (PDT)—a light-triggered chemical reaction that generates localized tissue damage for disease treatments—usually has side effects, and thus patients receiving photosensitizers should be kept away from direct light to avoid skin phototoxicity. In this study, a clinically therapeutic antibody cetuximab (C225) was conjugated to the surface of methoxy poly(ethylene glycol)-b-poly(lactide) (mPEG-b-PLA) micelles via thiol-maleimide coupling to allow tumor-targetable chlorin e6 (Ce6) delivery. Our results demonstrate that more C225-conjugated Ce6-loaded polymeric micelles (C225-Ce6/PM) were selectively taken up than Ce6/PM or IgG conjugated Ce6/PM by epidermal growth factor receptor (EGFR)-overexpressing A431 cells observed by confocal laser scanning microscopy (CLSM), thereby decreasing the IC₅₀ value of Ce6-mediated PDT from 0.42 to 0.173 μM. No significant differences were observed in cellular uptake study or IC₅₀ value between C225-Ce6/PM and Ce6/PM groups in lower EGFR expression HT-29 cells. For antitumor study, the tumor volumes in the C225-Ce6/PM-PDT group (percentage of tumor growth inhibition, TGI% = 84.8) were significantly smaller than those in the Ce6-PDT (TGI% = 38.4) and Ce6/PM-PDT groups (TGI% = 53.3) (p < 0.05) at day 21 through reduced cell proliferation in A431 xenografted mice. These results indicated that active EGFR targeting of photosensitizer-loaded micelles provides a possible way to resolve the dose-limiting toxicity of conventional photosensitizers and represents a potential delivery system for PDT in a clinical setting. Full article

(This article belongs to the Special Issue Nanomaterials for Imaging, Diagnosis or Therapy)

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15 pages, 29433 KiB

Open AccessArticle

Toxicity of Pristine and Chemically Functionalized Fullerenes to White Rot Fungus Phanerochaete chrysosporium

by Zhu Ming, Shicheng Feng, Ailimire Yilihamu, Qiang Ma, Shengnan Yang and Sheng-Tao Yang

Nanomaterials 2018, 8(2), 120; https://doi.org/10.3390/nano8020120 - 22 Feb 2018

Cited by 23 | Viewed by 5470

Abstract

Fullerenes are widely produced and applied carbon nanomaterials that require a thorough investigation into their environmental hazards and risks. In this study, we compared the toxicity of pristine fullerene (C₆₀) and carboxylated fullerene (C₆₀-COOH) to white rot fungus Phanerochaete [...] Read more.

Fullerenes are widely produced and applied carbon nanomaterials that require a thorough investigation into their environmental hazards and risks. In this study, we compared the toxicity of pristine fullerene (C₆₀) and carboxylated fullerene (C₆₀-COOH) to white rot fungus Phanerochaete chrysosporium. The influence of fullerene on the weight increase, fibrous structure, ultrastructure, enzyme activity, and decomposition capability of P. chrysosporium was investigated to reflect the potential toxicity of fullerene. C₆₀ did not change the fresh and dry weights of P. chrysosporium but C₆₀-COOH inhibited the weight gain at high concentrations. Both C₆₀ and C₆₀-COOH destroyed the fibrous structure of the mycelia. The ultrastructure of P. chrysosporium was changed by C₆₀-COOH. Pristine C₆₀ did not affect the enzyme activity of the P. chrysosporium culture system while C₆₀-COOH completely blocked the enzyme activity. Consequently, in the liquid culture, P. chrysosporium lost the decomposition activity at high C₆₀-COOH concentrations. The decreased capability in degrading wood was observed for P. chrysosporium exposed to C₆₀-COOH. Our results collectively indicate that chemical functionalization enhanced the toxicity of fullerene to white rot fungi and induced the loss of decomposition activity. The environmental risks of fullerene and its disturbance to the carbon cycle are discussed. Full article

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12 pages, 2320 KiB

Open AccessCommunication

Visualization of MMP-2 Activity Using Dual-Probe Nanoparticles to Detect Potential Metastatic Cancer Cells

by Aeju Lee, Sung Hoon Kim, Hyun Lee, Bohee Kim, Yoon Suk Kim and Jaehong Key

Nanomaterials 2018, 8(2), 119; https://doi.org/10.3390/nano8020119 - 21 Feb 2018

Cited by 12 | Viewed by 5755

Abstract

Matrix metalloproteinases (MMPs) are a family of zinc-dependent enzymes capable of degrading extracellular matrix components. Previous studies have shown that the upregulation of MMP-2 is closely related to metastatic cancers. While Western blotting, zymography, and Enzyme-Linked Immunosorbent Assays (ELISA) can be used to [...] Read more.

Matrix metalloproteinases (MMPs) are a family of zinc-dependent enzymes capable of degrading extracellular matrix components. Previous studies have shown that the upregulation of MMP-2 is closely related to metastatic cancers. While Western blotting, zymography, and Enzyme-Linked Immunosorbent Assays (ELISA) can be used to measure the amount of MMP-2 activity, it is not possible to visualize the dynamic MMP-2 activities of cancer cells using these techniques. In this study, MMP-2-activated poly(lactic-co-glycolic acid) with polyethylenimine (MMP-2-PLGA-PEI) nanoparticles were developed to visualize time-dependent MMP-2 activities. The MMP-2-PLGA-PEI nanoparticles contain MMP-2-activated probes that were detectable via fluorescence microscopy only in the presence of MMP-2 activity, while the Rhodamine-based probes in the nanoparticles were used to continuously visualize the location of the nanoparticles. This approach allowed us to visualize MMP-2 activities in cancer cells and their microenvironment. Our results showed that the MMP-2-PLGA-PEI nanoparticles were able to distinguish between MMP-2-positive (HaCat) and MMP-2-negative (MCF-7) cells. While the MMP-2-PLGA-PEI nanoparticles gave fluorescent signals recovered by active recombinant MMP-2, there was no signal recovery in the presence of an MMP-2 inhibitor. In conclusion, MMP-2-PLGA-PEI nanoparticles are an effective tool to visualize dynamic MMP-2 activities of potential metastatic cancer cells. Full article

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7 pages, 846 KiB

Open AccessArticle

A Brief Note on the Magnetowetting of Magnetic Nanofluids on AAO Surfaces

by Yu-Chin Chien and Huei Chu Weng

Nanomaterials 2018, 8(2), 118; https://doi.org/10.3390/nano8020118 - 20 Feb 2018

Cited by 14 | Viewed by 4605

Abstract

In magnetowetting, the material properties of liquid, surface morphology of solid, and applied external field are three major factors used to determine the wettability of a liquid droplet on a surface. For wetting measurements, an irregular or uneven surface could result in a [...] Read more.

In magnetowetting, the material properties of liquid, surface morphology of solid, and applied external field are three major factors used to determine the wettability of a liquid droplet on a surface. For wetting measurements, an irregular or uneven surface could result in a significant experimental uncertainty. The periodic array with a hexagonal symmetry structure is an advantage of the anodic aluminum oxide (AAO) structure. This study presents the results of the wetting properties of magnetic nanofluid sessile droplets on surfaces of various AAO pore sizes under an applied external magnetic field. Stable, water-based magnetite nanofluids are prepared by combining the chemical co-precipitation with the sol-gel technique, and AAO surfaces are then generated by anodizing the aluminum sheet in the beginning. The influence of pore size and magnetic field gradient on the magnetowetting of magnetic nanofluids on AAO surfaces is then investigated by an optical test system. Experimental results show that increasing the processing voltage of AAO templates could result in enhanced non-wettability behavior; that is, the increase in AAO pore size could lead to the increase in contact angle. The contact angle could be reduced by the applied magnetic field gradient. In general, the magnetic field has a more significant effect at smaller AAO pore sizes. Full article

(This article belongs to the Special Issue Nanomaterials for Renewable and Sustainable Energy)

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16 pages, 32670 KiB

Open AccessArticle

Promotion of Vascular Morphogenesis of Endothelial Cells Co-Cultured with Human Adipose-Derived Mesenchymal Stem Cells Using Polycaprolactone/Gelatin Nanofibrous Scaffolds

by Yun-Min Kook, Hyerim Kim, Sujin Kim, Chan Yeong Heo, Min Hee Park, Kangwon Lee and Won-Gun Koh

Nanomaterials 2018, 8(2), 117; https://doi.org/10.3390/nano8020117 - 18 Feb 2018

Cited by 40 | Viewed by 7182

Abstract

New blood vessel formation is essential for tissue regeneration to deliver oxygen and nutrients and to maintain tissue metabolism. In the field of tissue engineering, in vitro fabrication of new artificial vessels has been a longstanding challenge. Here we developed a technique to [...] Read more.

New blood vessel formation is essential for tissue regeneration to deliver oxygen and nutrients and to maintain tissue metabolism. In the field of tissue engineering, in vitro fabrication of new artificial vessels has been a longstanding challenge. Here we developed a technique to reconstruct a microvascular system using a polycaprolactone (PCL)/gelatin nanofibrous structure and a co-culture system. Using a simple electrospinning process, we fabricated three-dimensional mesh scaffolds to support the sprouting of human umbilical vein endothelial cells (HUVECs) along the electrospun nanofiber. The co-culture with adipose-derived mesenchymal stem cells (ADSCs) supported greater sprouting of endothelial cells (ECs). In a two-dimensional culture system, angiogenic cell assembly produced more effective direct intercellular interactions and paracrine signaling from ADSCs to assist in the vascular formation of ECs, compared to the influence of growth factor. Although vascular endothelial growth factor and sphingosine-1-phosphate were present during the culture period, the presence of ADSCs was the most important factor for the construction of a cell-assembled structure in the two-dimensional culture system. On the contrary, HUVECs co-cultured on PCL/gelatin nanofiber scaffolds produced mature and functional microvessel and luminal structures with a greater expression of vascular markers, including platelet endothelial cell adhesion molecule-1 and podocalyxin. Furthermore, both angiogenic factors and cellular interactions with ADSCs through direct contact and paracrine molecules contributed to the formation of enhanced engineered blood vessel structures. It is expected that the co-culture system of HUVECs and ADSCs on bioengineered PCL/gelatin nanofibrous scaffolds will promote robust and functional microvessel structures and will be valuable for the regeneration of tissue with restored blood vessels. Full article

(This article belongs to the Special Issue The Fabrication and Application of Nanofibers)

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22 pages, 1890 KiB

Open AccessArticle

Nanocantilevers with Adjustable Static Deflection and Significantly Tunable Spectrum Resonant Frequencies for Applications in Nanomechanical Mass Sensors

by Ivo Stachiv and Petr Sittner

Nanomaterials 2018, 8(2), 116; https://doi.org/10.3390/nano8020116 - 17 Feb 2018

Cited by 20 | Viewed by 4889

Abstract

Nanocantilevers have become key components of nanomechanical sensors that exploit changes in their resonant frequencies or static deflection in response to the environment. It is necessary that they can operate at a given, but adjustable, resonant frequency and/or static deflection ranges. Here we [...] Read more.

Nanocantilevers have become key components of nanomechanical sensors that exploit changes in their resonant frequencies or static deflection in response to the environment. It is necessary that they can operate at a given, but adjustable, resonant frequency and/or static deflection ranges. Here we propose a new class of nanocantilevers with a significantly tunable spectrum of the resonant frequencies and changeable static deflection utilizing the unique properties of a phase-transforming NiTi film sputtered on the usual nanotechnology cantilever materials. The reversible frequency tuning and the adjustable static deflection are obtained by intentionally changing the Young’s modulus and the interlayer stress of the NiTi film during its phase transformation, while the usual cantilever elastic materials guarantee a high frequency actuation (up to tens of MHz). By incorporating the NiTi phase transformation characteristic into the classical continuum mechanics theory we present theoretical models that account for the nanocantilever frequency shift and variation in static deflection caused by a phase transformation of NiTi film. Due to the practical importance in nanomechanical sensors, we carry out a complete theoretical analysis and evaluate the impact of NiTi film on the cantilever Young’s modulus, static deflection, and the resonant frequencies. Moreover, the importance of proposed NiTi nanocantilever is illustrated on the nanomechanical based mass sensors. Our findings will be of value in the development of advanced nanotechnology sensors with intentionally-changeable physical and mechanical properties. Full article

(This article belongs to the Special Issue Nanomaterials for Sensing Applications)

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18 pages, 4732 KiB

Open AccessArticle

Functionalized Asymmetric Bola-Type Amphiphiles for Efficient Gene and Drug Delivery

by Zheng Huang, Dong-Mei Zhao, Xuan Deng, Ji Zhang, Yi-Mei Zhang and Xiao-Qi Yu

Nanomaterials 2018, 8(2), 115; https://doi.org/10.3390/nano8020115 - 17 Feb 2018

Cited by 18 | Viewed by 4806

Abstract

The studies of bolaamphiphile-based nanoparticles as delivery vectors are still rudimentary and under development. In this study, several asymmetric bolaamphiphiles containing lysine and another moiety with special functions, such as pH-sensitive or cell-targeting property, were designed and synthesized. The potentials of these bolaamphiphile-based [...] Read more.

The studies of bolaamphiphile-based nanoparticles as delivery vectors are still rudimentary and under development. In this study, several asymmetric bolaamphiphiles containing lysine and another moiety with special functions, such as pH-sensitive or cell-targeting property, were designed and synthesized. The potentials of these bolaamphiphile-based nanoparticles as versatile vectors for both nucleic acids and chemical drugs were studied. With the presence of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), these amphiphiles could be prepared into bolasomes, which showed good DNA binding ability and could condense plasmid DNA into nanoparticles with appropriate size and surface potential. Lys-His, which has a pH-sensitive histidine on one head, exhibited higher transfection efficiency than the symmetric counterpart and comparable efficiency to commercially available transfection reagent. Mechanism studies confirmed that the bolaplexes formed from Lys-His might induce the highest cellular uptake and the best endosomal escape ability. On the other hand, these bolaamphiphiles also exhibited good drug loading ability. The self-assembly vesicles could efficiently encapsulate the hydrophobic anti-cancer drug doxorubicin (DOX) in aqueous solution with high drug loading content and encapsulation efficiency. Confocal laser scanning microscopy (CLSM) experiment and cell viability assay exhibited a controlled release of the drug with the assistance of bolasomes. It was shown that such bolaamphiphiles have great potential as nano-vectors for both drug and gene or their co-delivery. Full article

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11 pages, 5827 KiB

Open AccessArticle

Memristic Characteristics from Bistable to Tristable Memory with Controllable Charge Trap Carbon Nanotubes

by Lei Li and Dianzhong Wen

Nanomaterials 2018, 8(2), 114; https://doi.org/10.3390/nano8020114 - 17 Feb 2018

Cited by 12 | Viewed by 4413

Abstract

The incorporation of the one-dimensional carbon nanomaterial carbon nanotubes (CNTs) in poly(methyl methacrylate) (PMMA) was found to successfully develop a resistive switching. It implements memristic characteristics which shift from bistable to tristable memory. The localized current pathways in the organic nanocomposite layers for [...] Read more.

The incorporation of the one-dimensional carbon nanomaterial carbon nanotubes (CNTs) in poly(methyl methacrylate) (PMMA) was found to successfully develop a resistive switching. It implements memristic characteristics which shift from bistable to tristable memory. The localized current pathways in the organic nanocomposite layers for each intermediate resistive state (IRS) are attributed to the trapping mechanism consistent with the fluorescent measurements. Multi-bit organic memories have attracted considerable interest, which provide an effective way to increase the memory density per unit cell area. This study will be useful for the development and tuning of multi-bit storable organic nanocomposite memory device systems. Full article

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14 pages, 2600 KiB

Open AccessArticle

Small-Sized Mg–Al LDH Nanosheets Supported on Silica Aerogel with Large Pore Channels: Textural Properties and Basic Catalytic Performance after Activation

by Lijun Wang, Yusen Wang, Xiaoxia Wang, Xiaolan Feng, Xiao Ye and Jie Fu

Nanomaterials 2018, 8(2), 113; https://doi.org/10.3390/nano8020113 - 16 Feb 2018

Cited by 15 | Viewed by 5130

Abstract

Layered double hydroxides (LDHs) have been widely used as an important subset of solid base catalysts. However, developing low-cost, small-sized LDH nanoparticles with enhanced surface catalytic sites remains a challenge. In this work, silica aerogel (SA)-supported, small-sized Mg–Al LDH nanosheets were successfully prepared [...] Read more.

Layered double hydroxides (LDHs) have been widely used as an important subset of solid base catalysts. However, developing low-cost, small-sized LDH nanoparticles with enhanced surface catalytic sites remains a challenge. In this work, silica aerogel (SA)-supported, small-sized Mg–Al LDH nanosheets were successfully prepared by one-pot coprecipitation of Mg and Al ions in an alkaline suspension of crushed silica aerogel. The supported LDH nanosheets were uniformly dispersed in the SA substrate with the smallest average radial diameter of 19.2 nm and the thinnest average thickness of 3.2 nm, both dimensions being significantly less than those of the vast majority of LDH nanoparticles reported. The SA/LDH composites also showed large pore volume (up to 1.3 cm3·g) and pore diameter (>9 nm), and therefore allow efficient access of reactants to the edge catalytic sites of LDH nanosheets. In a base-catalyzed Henry reaction of benzaldehyde with nitromethane, the SA/LDH catalysts showed high reactant conversions and favorable stability in 6 successive cycles of reactions. The low cost of the SA carrier and LDH precursors, easy preparation method, and excellent catalytic properties make these SA/LDH composites a competitive example of solid-base catalysts. Full article

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20 pages, 4358 KiB

Open AccessArticle

2D SnO₂ Nanosheets: Synthesis, Characterization, Structures, and Excellent Sensing Performance to Ethylene Glycol

by Wenjin Wan, Yuehua Li, Xingping Ren, Yinping Zhao, Fan Gao and Heyun Zhao

Nanomaterials 2018, 8(2), 112; https://doi.org/10.3390/nano8020112 - 16 Feb 2018

Cited by 128 | Viewed by 10298

Abstract

Two dimensional (2D)SnO₂ nanosheets were synthesized by a substrate-free hydrothermal route using sodium stannate and sodium hydroxide in a mixed solvent of absolute ethanol and deionized water at a lower temperature of 130 °C. The characterization results of the morphology, microstructure, and [...] Read more.

Two dimensional (2D)SnO₂ nanosheets were synthesized by a substrate-free hydrothermal route using sodium stannate and sodium hydroxide in a mixed solvent of absolute ethanol and deionized water at a lower temperature of 130 °C. The characterization results of the morphology, microstructure, and surface properties of the as-prepared products demonstrated that SnO₂ nanosheets with a tetragonal rutile structure, were composed of oriented SnO₂ nanoparticles with a diameter of 6–12 nm. The X-ray diffraction (XRD) and high-resolution transmission electron microscope (FETEM) results demonstrated that the dominant exposed surface of the SnO₂ nanoparticles was (101), but not (110). The growth and formation was supposed to follow the oriented attachment mechanism. The SnO₂ nanosheets exhibited an excellent sensing response toward ethylene glycol at a lower optimal operating voltage of 3.4 V. The response to 400 ppm ethylene glycol reaches 395 at 3.4 V. Even under the low concentration of 5, 10, and 20 ppm, the sensor exhibited a high response of 6.9, 7.8, and 12.0 to ethylene glycol, respectively. The response of the SnO₂ nanosheets exhibited a linear dependence on the ethylene glycol concentration from 5 to 1000 ppm. The excellent sensing performance was attributed to the present SnO₂ nanoparticles with small size close to the Debye length, the larger specific surface, the high-energy exposed facets of the (101) surface, and the synergistic effects of the SnO₂ nanoparticles of the nanosheets. Full article

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14 pages, 29275 KiB

Open AccessArticle

The Role of Nano-TiO2 Lubricating Fluid on the Hot Rolled Surface and Metallographic Structure of SS41 Steel

by Yanan Meng, Jianlin Sun, Ping Wu, Chang Dong and Xudong Yan

Nanomaterials 2018, 8(2), 111; https://doi.org/10.3390/nano8020111 - 16 Feb 2018

Cited by 25 | Viewed by 4624

Abstract

In this paper, nano-TiO2lubricating fluid was chosen as an advanced rolling lubricant to investigate its effect on the hot rolled surface and metallographic structure of SS41 steel strips. The tribological performances of nano-TiO2 lubricating fluid were measured by a four-ball tribotester. The hot [...] Read more.

In this paper, nano-TiO2lubricating fluid was chosen as an advanced rolling lubricant to investigate its effect on the hot rolled surface and metallographic structure of SS41 steel strips. The tribological performances of nano-TiO2 lubricating fluid were measured by a four-ball tribotester. The hot rolling experiments under different lubrication conditions were carried out by a four-high rolling mill. The surface morphology, oxide scales and metallographic structure after hot rolling were observed using a confocal laser scanning microscope and scanning electron microscope (SEM), respectively. The composition of surface attachments was analyzed with X-ray photoelectron spectroscopy (XPS). The results indicate that the nano-TiO2 lubricating fluid has a better tribological performance. The surface defects on the hot rolled surface could be decreased. The phase composition of the surface still appears as a mixture of ferrite and pearlite. The surface of steel strips is not micro-alloyed with titanium as predicted. Additionally, the grain size of rolled steel strips which were lubricated with the nano-TiO2lubricating fluid decreased by nearly 50%, compared with traditional lubricating fluid. Furthermore, it was found that the thickness of the oxide layers on the surface reduced, whilst the Rockwell hardness of the oxide layers was enhanced as nano-TiO2 lubricating fluid was applied. Full article

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16 pages, 1720 KiB

Open AccessArticle

Development and Characterization of Solid Lipid Nanoparticles Loaded with a Highly Active Doxorubicin Derivative

by Barbara Stella, Elena Peira, Chiara Dianzani, Marina Gallarate, Luigi Battaglia, Casimiro Luca Gigliotti, Elena Boggio, Umberto Dianzani and Franco Dosio

Nanomaterials 2018, 8(2), 110; https://doi.org/10.3390/nano8020110 - 16 Feb 2018

Cited by 58 | Viewed by 5804

Abstract

Solid lipid nanoparticles (SLNs) comprise a versatile drug delivery system that has been developed for the treatment of a variety of diseases. The present study will investigate the feasibility of entrapping an active doxorubicin prodrug (a squalenoyl-derivative) in SLNs. The doxorubicin derivative-loaded SLNs [...] Read more.

Solid lipid nanoparticles (SLNs) comprise a versatile drug delivery system that has been developed for the treatment of a variety of diseases. The present study will investigate the feasibility of entrapping an active doxorubicin prodrug (a squalenoyl-derivative) in SLNs. The doxorubicin derivative-loaded SLNs are spherically shaped, have a mean diameter of 300–400 nm and show 85% w/w drug entrapment efficiency. The effects on cell growth of loaded SLNs, free doxorubicin and the prodrug have been examined using cytotoxicity and colony-forming assays in both human ovarian cancer line A2780 wild-type and doxorubicin-resistant cells. Further assessments as to the treatment’s ability to induce cell death by apoptosis have been carried out by analyzing annexin-V staining and the activation of caspase-3. The in vitro data demonstrate that the delivery of the squalenoyl-doxorubicin derivative by SLNs increases its cytotoxic activity, as well as its apoptosis effect. This effect was particularly evident in doxorubicin-resistant cells. Full article

(This article belongs to the Special Issue Pharmaceutical Nanotechnology)

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19 pages, 5225 KiB

Open AccessArticle

Using Polarized Spectroscopy to Investigate Order in Thin-Films of Ionic Self-Assembled Materials Based on Azo-Dyes

by Miguel R. Carro-Temboury Martin Kühnel, Mariam Ahmad, Frederik Andersen, Ári Brend Bech, H. Krestian L. Bendixen, Patrick R. Nawrocki, Anders J. Bloch, Ilkay Bora, Tahreem A. Bukhari, Nicolai V. Bærentsen, Jens Carstensen, Smeeah Chima, Helene Colberg, Rasmus T. Dahm, Joshua A. Daniels, Nermin Dinckan, Mohamed El Idrissi, Ricci Erlandsen, Marc Førster, Yasmin Ghauri, Mikkel Gold, Andreas Hansen, Kenn Hansen, Mathias Helmsøe-Zinck, Mathias Henriksen, Sophus V. Hoffmann, Louise O. H. Hyllested, Casper Jensen, Amalie S. Kallenbach, Kirandip Kaur, Suheb R. Khan, Emil T. S. Kjær, Bjørn Kristiansen, Sylvester Langvad, Philip M. Lund, Chastine F. Munk, Theis Møller, Ola M. Z. Nehme, Mathilde Rove Nejrup, Louise Nexø, Simon Skødt Holm Nielsen, Nicolai Niemeier, Lasse V. Nikolajsen, Peter C. T. Nøhr, Dominik B. Orlowski, Marc Overgaard, Jacob Skaarup Ovesen, Lucas Paustian, Adam S. Pedersen, Mathias K. Petersen, Camilla M. Poulsen, Louis Praeger-Jahnsen, L. Sonia Qureshi, Nicolai Ree, Louise S. Schiermacher, Martin B. Simris, Gorm Smith, Heidi N. Smith, Alexander K. Sonne, Marko R. Zenulovic, Alma Winther Sørensen, Karina Sørensen, Emil Vogt, Andreas Væring, Jonas Westermann, Sevin B. Özcan and Thomas Just Sørensen Show full author list Hide full author list

Nanomaterials 2018, 8(2), 109; https://doi.org/10.3390/nano8020109 - 15 Feb 2018

Viewed by 5898

Abstract

Three series of ionic self-assembled materials based on anionic azo-dyes and cationic benzalkonium surfactants were synthesized and thin films were prepared by spin-casting. These thin films appear isotropic when investigated with polarized optical microscopy, although they are highly anisotropic. Here, three series of [...] Read more.

Three series of ionic self-assembled materials based on anionic azo-dyes and cationic benzalkonium surfactants were synthesized and thin films were prepared by spin-casting. These thin films appear isotropic when investigated with polarized optical microscopy, although they are highly anisotropic. Here, three series of homologous materials were studied to rationalize this observation. Investigating thin films of ordered molecular materials relies to a large extent on advanced experimental methods and large research infrastructure. A statement that in particular is true for thin films with nanoscopic order, where X-ray reflectometry, X-ray and neutron scattering, electron microscopy and atom force microscopy (AFM) has to be used to elucidate film morphology and the underlying molecular structure. Here, the thin films were investigated using AFM, optical microscopy and polarized absorption spectroscopy. It was shown that by using numerical method for treating the polarized absorption spectroscopy data, the molecular structure can be elucidated. Further, it was shown that polarized optical spectroscopy is a general tool that allows determination of the molecular order in thin films. Finally, it was found that full control of thermal history and rigorous control of the ionic self-assembly conditions are required to reproducibly make these materials of high nanoscopic order. Similarly, the conditions for spin-casting are shown to be determining for the overall thin film morphology, while molecular order is maintained. Full article

(This article belongs to the Special Issue Mechanics, Electrical and Optical Properties of Nano-Thin Films)

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13 pages, 1662 KiB

Open AccessArticle

Magnetic Nanoparticles Interact and Pass an In Vitro Co-Culture Blood-Placenta Barrier Model

by Elena K. Müller, Christine Gräfe, Frank Wiekhorst, Christian Bergemann, Andreas Weidner, Silvio Dutz and Joachim H. Clement

Nanomaterials 2018, 8(2), 108; https://doi.org/10.3390/nano8020108 - 14 Feb 2018

Cited by 33 | Viewed by 5463

Abstract

Magnetic nanoparticles are interesting tools for biomedicine. Before application, critical prerequisites have to be fulfilled. An important issue is the contact and interaction with biological barriers such as the blood-placenta barrier. In order to study these processes in detail, suitable in vitro models [...] Read more.

Magnetic nanoparticles are interesting tools for biomedicine. Before application, critical prerequisites have to be fulfilled. An important issue is the contact and interaction with biological barriers such as the blood-placenta barrier. In order to study these processes in detail, suitable in vitro models are needed. For that purpose a blood-placenta barrier model based on the trophoblast-like cell line BeWo and primary placenta-derived pericytes was established. This model was characterized by molecular permeability, transepithelial electrical resistance and cell-cell-contact markers. Superparamagnetic iron oxide nanoparticles (SPIONs) with cationic, anionic or neutral surface charge were applied. The localization of the nanoparticles within the cells was illustrated by histochemistry. The time-dependent passage of the nanoparticles through the BeWo/pericyte barrier was measured by magnetic particle spectroscopy and atomic absorption spectroscopy. Cationically coated SPIONs exhibited the most extensive interaction with the BeWo cells and remained primarily in the BeWo/pericyte cell layer. In contrast, SPIONs with neutral and anionic surface charge were able to pass the cell layer to a higher extent and could be detected beyond the barrier after 24 h. This study showed that the mode of SPION interaction with and passage through the in vitro blood-placenta barrier model depends on the surface charge and the duration of treatment. Full article

(This article belongs to the Special Issue Magnetic Nanoparticles in Biological Applications)

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10 pages, 5775 KiB

Open AccessArticle

Qualitative and Quantitative Detection of PrP^Sc Based on the Controlled Release Property of Magnetic Microspheres Using Surface Plasmon Resonance (SPR)

by Zhichao Lou, He Han, Dun Mao, Yibin Jiang and Jianyue Song

Nanomaterials 2018, 8(2), 107; https://doi.org/10.3390/nano8020107 - 13 Feb 2018

Cited by 20 | Viewed by 4439

Abstract

Prion protein (PrP^Sc) has drawn widespread attention due to its pathological potential to prion diseases. In this work, we constructed a novel surface plasmon resonance (SPR) detection assay involving magnetic microspheres (MMs) and its controlled release property, for selective capture, embedding, [...] Read more.

Prion protein (PrP^Sc) has drawn widespread attention due to its pathological potential to prion diseases. In this work, we constructed a novel surface plasmon resonance (SPR) detection assay involving magnetic microspheres (MMs) and its controlled release property, for selective capture, embedding, concentration, and SPR detection of PrP^Sc with high sensitivity and specificity. Aptamer-modified magnetic particles (AMNPs) were used to specifically capture PrP^Sc. Amphiphilic copolymer was used to embed the labeled PrP^Sc and form magnetic microspheres to isolate PrP^Sc from the external environment. Static magnetic and alternating magnetic fields were used to concentrate and control release the embedded PrP^Sc, respectively. Finally, the released AMNPs-labeled PrP^Sc was detected by SPR which was equipped with a bare gold sensing film. A good linear relationship was obtained between SPR responses and the logarithm of PrP^Sc concentrations over a range of 0.01–1000 ng/mL. The detection sensitivity for PrP^Sc was improved by 10 fold compared with SPR direct detection format. The specificity of the present biosensor was also determined by PrP^C and other reagents as controls. This proposed approach could also be used to isolate and detect other highly pathogenic biomolecules with similar structural characteristics by altering the corresponding aptamer in the AMNPs conjugates. Full article

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17 pages, 6682 KiB

Open AccessArticle

Synthesis of Graphite Oxide with Different Surface Oxygen Contents Assisted Microwave Radiation

by Adriana Ibarra-Hernández, Alejandro Vega-Rios and Velia Osuna

Nanomaterials 2018, 8(2), 106; https://doi.org/10.3390/nano8020106 - 13 Feb 2018

Cited by 18 | Viewed by 7647

Abstract

Graphite oxide is synthesized via oxidation reaction using oxidant compounds that have lattice defects by the incorporation of unlike functional groups. Herein, we report the synthesis of the graphite oxide with diverse surface oxygen content through three (B, C, D) different modified versions [...] Read more.

Graphite oxide is synthesized via oxidation reaction using oxidant compounds that have lattice defects by the incorporation of unlike functional groups. Herein, we report the synthesis of the graphite oxide with diverse surface oxygen content through three (B, C, D) different modified versions of the Hummers method assisted microwave radiation compared with the conventional graphite oxide sample obtained by Hummers method (A). These methods allow not only the production of graphite oxide but also reduced graphene oxide, without undergoing chemical, thermal, or mechanical reduction steps. The values obtained of C/O ratio were ~2, 3.4, and ~8.5 for methodologies C, B, and D, respectively, indicating the presence of graphite oxide and reduced graphene oxide, according to X-ray photoelectron spectroscopy. Raman spectroscopy of method D shows the fewest structural defects compared to the other methodologies. The results obtained suggest that the permanganate ion produces reducing species during graphite oxidation. The generation of these species is attributed to a reversible reaction between the permanganate ion with π electrons, ions, and radicals produced after treatment with microwave radiation. Full article

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27 pages, 8527 KiB

Open AccessReview

Graphene Modified TiO₂ Composite Photocatalysts: Mechanism, Progress and Perspective

by Bo Tang, Haiqun Chen, Haoping Peng, Zhengwei Wang and Weiqiu Huang

Nanomaterials 2018, 8(2), 105; https://doi.org/10.3390/nano8020105 - 12 Feb 2018

Cited by 145 | Viewed by 10837

Abstract

Graphene modified TiO₂ composite photocatalysts have drawn increasing attention because of their high performance. Some significant advancements have been achieved with the continuous research, such as the corresponding photocatalytic mechanism that has been revealed. Specific influencing factors have been discovered and potential [...] Read more.

Graphene modified TiO₂ composite photocatalysts have drawn increasing attention because of their high performance. Some significant advancements have been achieved with the continuous research, such as the corresponding photocatalytic mechanism that has been revealed. Specific influencing factors have been discovered and potential optimizing methods are proposed. The latest developments in graphene assisted TiO₂ composite photocatalysts are abstracted and discussed. Based on the primary reasons behind the observed phenomena of these composite photocatalysts, probable development directions and further optimizing strategies are presented. Moreover, several novel detective technologies—beyond the decomposition test—which can be used to judge the photocatalytic performances of the resulting photocatalysts are listed and analyzed. Although some objectives have been achieved, new challenges still exist and hinder the widespread application of graphene-TiO₂ composite photocatalysts, which deserves further study. Full article

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10 pages, 2766 KiB

Open AccessArticle

Clearly Transparent Nanopaper from Highly Concentrated Cellulose Nanofiber Dispersion Using Dilution and Sonication

by Takaaki Kasuga, Noriyuki Isobe, Hitomi Yagyu, Hirotaka Koga and Masaya Nogi

Nanomaterials 2018, 8(2), 104; https://doi.org/10.3390/nano8020104 - 12 Feb 2018

Cited by 33 | Viewed by 6756

Abstract

Nanopaper prepared from holocellulose pulp is one of the best substrates for flexible electronics because of its high thermal resistance and high clear transparency. However, the clearness of nanopaper decreases with increasing concentration of the starting cellulose nanofiber dispersion—with the use of a [...] Read more.

Nanopaper prepared from holocellulose pulp is one of the best substrates for flexible electronics because of its high thermal resistance and high clear transparency. However, the clearness of nanopaper decreases with increasing concentration of the starting cellulose nanofiber dispersion—with the use of a 2.2 wt % dispersion, for example—resulting in translucent nanopaper with a high haze of 44%. To overcome this problem, we show that the dilution of this high-concentration dispersion with water followed by sonication for 10 s reduces the haze to less than 10% while maintaining the high thermal resistance of the nanopaper. Furthermore, the combination of water dilution and a short sonication treatment improves the clearness of the nanopaper, which would translate into cost savings for the transportation and storage of this highly concentrated cellulose nanofiber dispersion. Finally, we demonstrate the improvement of the electrical conductivity of clear transparent nanopaper prepared from an initially high-concentration dispersion by dropping and heating silver nanowire ink on the nanopaper. These achievements will pave the way toward the realization of the mass production of nanofiber-based flexible devices. Full article

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13 pages, 6170 KiB

Open AccessArticle

Electrochemical Preparation of Polyaniline Nanowires with the Used Electrolyte Solution Treated with the Extraction Process and Their Electrochemical Performance

by Ying Wu, Jixiao Wang, Bin Ou, Song Zhao, Zhi Wang and Shichang Wang

Nanomaterials 2018, 8(2), 103; https://doi.org/10.3390/nano8020103 - 12 Feb 2018

Cited by 10 | Viewed by 4612

Abstract

Electrochemical polymerization of aniline is one of the most promising methods to prepare polyaniline (PANI) materials. However, during this process, the electrolyte solution must be replaced after electropolymerization of a certain time because of the generation and the accumulation of the by-products, which [...] Read more.

Electrochemical polymerization of aniline is one of the most promising methods to prepare polyaniline (PANI) materials. However, during this process, the electrolyte solution must be replaced after electropolymerization of a certain time because of the generation and the accumulation of the by-products, which have significant effects on the morphology, purity and properties of PANI products. Treatment and recycling of the used electrolyte solution are worthwhile to study to reduce the high treatment cost of the used electrolyte solution containing aniline and its polymerization by-products. Here, the composition of the used electrolyte solution was separated and determined by high performance liquid chromatography coupled with diode array detection (HPLC-DAD) in the range of ultraviolet and visible (UV-Vis) light. The analysis results revealed that the used electrolyte solution consisted of aniline, p-hydroquinone (HQ), p-benzoquinone (BQ), co-oligomers of aniline and p-benzoquinone (CAB) and acid. Then, n-octanol and 2-octanone were selected as extracts to remove HQ, BQ and CAB from the used electrolyte solution. Following that, the recycled electrolyte solution was prepared by adjusting the concentration of aniline and acid of the aqueous phase, and the electrochemical polymerization process was conducted. Finally, the obtained PANI was characterized by scanning electron microscope (SEM) and electrochemical methods. The experimental results clearly demonstrate that the morphology and specific capacitance of PANI produced from the recycled electrolyte solution can be recovered completely. This research paves the way for reusing the used electrolyte solution for aniline electrochemical polymerization. Full article

(This article belongs to the Special Issue Synthesis and Characterization of Nanowires)

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18 pages, 1704 KiB

Open AccessReview

Advances in Targeted Pesticides with Environmentally Responsive Controlled Release by Nanotechnology

by Bingna Huang, Feifei Chen, Yue Shen, Kun Qian, Yan Wang, Changjiao Sun, Xiang Zhao, Bo Cui, Fei Gao, Zhanghua Zeng and Haixin Cui

Nanomaterials 2018, 8(2), 102; https://doi.org/10.3390/nano8020102 - 11 Feb 2018

Cited by 202 | Viewed by 15556

Abstract

Pesticides are the basis for defending against major biological disasters and important for ensuring national food security. Biocompatible, biodegradable, intelligent, and responsive materials are currently an emerging area of interest in the field of efficient, safe, and green pesticide formulation. Using nanotechnology to [...] Read more.

Pesticides are the basis for defending against major biological disasters and important for ensuring national food security. Biocompatible, biodegradable, intelligent, and responsive materials are currently an emerging area of interest in the field of efficient, safe, and green pesticide formulation. Using nanotechnology to design and prepare targeted pesticides with environmentally responsive controlled release via compound and chemical modifications has also shown great potential in creating novel formulations. In this review, special attention has been paid to intelligent pesticides with precise controlled release modes that can respond to micro-ecological environment changes such as light-sensitivity, thermo-sensitivity, humidity sensitivity, soil pH, and enzyme activity. Moreover, establishing intelligent and controlled pesticide release technologies using nanomaterials are reported. These technologies could increase pesticide-loading, improve the dispersibility and stability of active ingredients, and promote target ability. Full article

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12 pages, 1127 KiB

Open AccessArticle

Determination of Non-Transferrin Bound Iron, Transferrin Bound Iron, Drug Bound Iron and Total Iron in Serum in a Rats after IV Administration of Sodium Ferric Gluconate Complex by Simple Ultrafiltration Inductively Coupled Plasma Mass Spectrometric Detection

by Murali K. Matta, Christopher R. Beekman, Adarsh Gandhi, Suresh Narayanasamy, Christopher D. Thomas, Adil Mohammad, Sharron Stewart, Lin Xu, Ashok Chockalingam, Katherine Shea, Vikram Patel and Rodney Rouse

Nanomaterials 2018, 8(2), 101; https://doi.org/10.3390/nano8020101 - 11 Feb 2018

Cited by 8 | Viewed by 5852

Abstract

A rapid, sensitive and specific ultrafiltration inductively-coupled plasma mass spectrometry method was developed and validated for the quantification of non-transferrin bound iron (NTBI), transferrin bound iron (TBI), drug bound iron (DI) and total iron (TI) in the same rat serum sample after intravenous [...] Read more.

A rapid, sensitive and specific ultrafiltration inductively-coupled plasma mass spectrometry method was developed and validated for the quantification of non-transferrin bound iron (NTBI), transferrin bound iron (TBI), drug bound iron (DI) and total iron (TI) in the same rat serum sample after intravenous (IV) administration of iron gluconate nanoparticles in sucrose solution (Ferrlecit^®). Ultrafiltration with a 30 kDa molecular cut-off filter was used for sample cleanup. Different elution solvents were used to separate each form of iron from sample serum. Isolated fractions were subjected to inductively-coupled mass spectrometric analysis after microwave digestion in 4% nitric acid. The reproducibility of the method was evaluated by precision and accuracy. The calibration curve demonstrated linearity from 5–500 ng/mL with a regression (r²) of more than 0.998. This method was effectively implemented to quantify rat pharmacokinetic study samples after intravenous administration of Ferrlecit^®. The method was successfully applied to a pharmacokinetic (PK) study of Ferrlecit in rats. The colloidal iron followed first order kinetics with half-life of 2.2 h and reached background or pre-dose levels after 12 h post-dosing. The drug shown a clearance of 0.31 mL/min/kg and volume of distribution of 0.05 L/kg. 19.4 ± 2.4 mL/h/kg. Full article

(This article belongs to the Special Issue Pharmaceutical Nanotechnology)

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7 pages, 2211 KiB

Open AccessArticle

Synthesis of Large-Scale Single-Crystalline Monolayer WS₂ Using a Semi-Sealed Method

by Feifei Lan, Ruixia Yang, Yongkuan Xu, Shengya Qian, Song Zhang, Hongjuan Cheng and Ying Zhang

Nanomaterials 2018, 8(2), 100; https://doi.org/10.3390/nano8020100 - 11 Feb 2018

Cited by 32 | Viewed by 6530

Abstract

As a two-dimensional semiconductor, WS₂ has attracted great attention due to its rich physical properties and potential applications. However, it is still difficult to synthesize monolayer single-crystalline WS₂ at larger scale. Here, we report the growth of large-scale triangular single-crystalline WS [...] Read more.

As a two-dimensional semiconductor, WS₂ has attracted great attention due to its rich physical properties and potential applications. However, it is still difficult to synthesize monolayer single-crystalline WS₂ at larger scale. Here, we report the growth of large-scale triangular single-crystalline WS₂ with a semi-sealed installation by chemical vapor deposition (CVD). Through this method, triangular single-crystalline WS₂ with an average length of more than 300 µm was obtained. The largest one was about 405 μm in length. WS₂ triangles with different sizes and thicknesses were analyzed by optical microscope and atomic force microscope (AFM). Their optical properties were evaluated by Raman and photoluminescence (PL) spectra. This report paves the way to fabricating large-scale single-crystalline monolayer WS₂, which is useful for the growth of high-quality WS₂ and its potential applications in the future. Full article

(This article belongs to the Special Issue Experimental Nanosciences, Computational Chemistry, and Data Analysis)

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29 pages, 1275 KiB

Open AccessReview

Current Application of Capillary Electrophoresis in Nanomaterial Characterisation and Its Potential to Characterise the Protein and Small Molecule Corona

by Andrew J. Chetwynd, Emily J. Guggenheim, Sophie M. Briffa, James A. Thorn, Iseult Lynch and Eugenia Valsami-Jones

Nanomaterials 2018, 8(2), 99; https://doi.org/10.3390/nano8020099 - 10 Feb 2018

Cited by 32 | Viewed by 9665

Abstract

Due to the increasing use and production of nanomaterials (NMs), the ability to characterise their physical/chemical properties quickly and reliably has never been so important. Proper characterisation allows a thorough understanding of the material and its stability, and is critical to establishing dose-response [...] Read more.

Due to the increasing use and production of nanomaterials (NMs), the ability to characterise their physical/chemical properties quickly and reliably has never been so important. Proper characterisation allows a thorough understanding of the material and its stability, and is critical to establishing dose-response curves to ascertain risks to human and environmental health. Traditionally, methods such as Transmission Electron Microscopy (TEM), Field Flow Fractionation (FFF) and Dynamic Light Scattering (DLS) have been favoured for size characterisation, due to their wide-availability and well-established protocols. Capillary Electrophoresis (CE) offers a faster and more cost-effective solution for complex dispersions including polydisperse or non-spherical NMs. CE has been used to rapidly separate NMs of varying sizes, shapes, surface modifications and compositions. This review will discuss the literature surrounding the CE separation techniques, detection and NM characteristics used for the analysis of a wide range of NMs. The potential of combining CE with mass spectrometry (CE-MS) will also be explored to further expand the characterisation of NMs, including the layer of biomolecules adsorbed to the surface of NMs in biological or environmental compartments, termed the acquired biomolecule corona. CE offers the opportunity to uncover new/poorly characterised low abundance and polar protein classes due to the high ionisation efficiency of CE-MS. Furthermore, the possibility of using CE-MS to characterise the poorly researched small molecule interactions within the NM corona is discussed. Full article

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