Nanomaterials

7675 KiB

Open AccessArticle

Study on Utilization of Carboxyl Group Decorated Carbon Nanotubes and Carbonation Reaction for Improving Strengths and Microstructures of Cement Paste

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

Nanomaterials 2016, 6(8), 153; https://doi.org/10.3390/nano6080153 - 19 Aug 2016

Cited by 26 | Viewed by 6315 | Correction

Abstract

Carbon nanotubes (CNTs) have excellent mechanical properties and can be used to reinforce cement-based materials. On the other hand, the reaction product of carbonation with hydroxides in hydrated cement paste can reduce the porosity of cement-based materials. In this study, a novel method [...] Read more.

Carbon nanotubes (CNTs) have excellent mechanical properties and can be used to reinforce cement-based materials. On the other hand, the reaction product of carbonation with hydroxides in hydrated cement paste can reduce the porosity of cement-based materials. In this study, a novel method to improve the strength of cement paste was developed through a synergy of carbon nanotubes decorated with carboxyl group and carbonation reactions. The experimental results showed that the carboxyl group (–COOH) of decorated carbon nanotubes and the surfactant can control the morphology of the calcium carbonate crystal of carbonation products in hydrated cement paste. The spindle-like calcium carbonate crystals showed great morphological differences from those observed in the conventional carbonation of cement paste. The spindle-like calcium carbonate crystals can serve as fiber-like reinforcements to reinforce the cement paste. By the synergy of the carbon nanotubes and carbonation reactions, the compressive and flexural strengths of cement paste were significantly improved and increased by 14% and 55%, respectively, when compared to those of plain cement paste. Full article

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

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8681 KiB

Open AccessArticle

A Novel Polyvinylidene Fluoride Tree-Like Nanofiber Membrane for Microfiltration

by Zongjie Li, Weimin Kang, Huihui Zhao, Min Hu, Na Wei, Jiuan Qiu and Bowen Cheng

Nanomaterials 2016, 6(8), 152; https://doi.org/10.3390/nano6080152 - 19 Aug 2016

Cited by 35 | Viewed by 6009

Abstract

A novel polyvinylidene fluoride (PVDF) tree-like nanofiber membrane (PVDF-TLNM) was fabricated by adding tetrabutylammonium chloride (TBAC) into a PVDF spinning solution via one-step electrospinning. The structure of the prepared membranes was characterized by field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy [...] Read more.

A novel polyvinylidene fluoride (PVDF) tree-like nanofiber membrane (PVDF-TLNM) was fabricated by adding tetrabutylammonium chloride (TBAC) into a PVDF spinning solution via one-step electrospinning. The structure of the prepared membranes was characterized by field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR) and pore size analysis, and the hydrophilic property and microfiltration performance were also evaluated. The results showed that the tree-like nanofiber was composed of trunk fibers and branch fibers with diameters of 100–500 nm and 5–100 nm, respectively. The pore size of PVDF-TLNM (0.36 μm) was smaller than that of a common nanofiber membrane (3.52 μm), and the hydrophilic properties of the membranes were improved significantly. The PVDF-TLNM with a thickness of 30 ± 2 μm showed a satisfactory retention ratio of 99.9% against 0.3 μm polystyrene (PS) particles and a high pure water flux of 2.88 × 10⁴ L·m⁻²·h⁻¹ under the pressure of 25 psi. This study highlights the potential benefits of this novel PVDF tree-like nanofiber membrane in the membrane field, which can achieve high flux rates at low pressure. Full article

(This article belongs to the Special Issue Environmental Applications and Implications of Nanotechnology)

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1452 KiB

Open AccessArticle

Pregnancy Vaccination with Gold Glyco-Nanoparticles Carrying Listeria monocytogenes Peptides Protects against Listeriosis and Brain- and Cutaneous-Associated Morbidities

by Ricardo Calderón-Gonzalez, Héctor Terán-Navarro, Elisabet Frande-Cabanes, Eva Ferrández-Fernández, Javier Freire, Soledad Penadés, Marco Marradi, Isabel García, Javier Gomez-Román, Sonsoles Yañez-Díaz and Carmen Álvarez-Domínguez

Nanomaterials 2016, 6(8), 151; https://doi.org/10.3390/nano6080151 - 19 Aug 2016

Cited by 29 | Viewed by 6760

Abstract

Listeriosis is a fatal infection for fetuses and newborns with two clinical main morbidities in the neonatal period, meningitis and diffused cutaneous lesions. In this study, we vaccinated pregnant females with two gold glyconanoparticles (GNP) loaded with two peptides, listeriolysin peptide 91–99 (LLO [...] Read more.

Listeriosis is a fatal infection for fetuses and newborns with two clinical main morbidities in the neonatal period, meningitis and diffused cutaneous lesions. In this study, we vaccinated pregnant females with two gold glyconanoparticles (GNP) loaded with two peptides, listeriolysin peptide 91–99 (LLO_91–99) or glyceraldehyde-3-phosphate dehydrogenase 1–22 peptide (GAPDH_1–22). Neonates born to vaccinated mothers were free of bacteria and healthy, while non-vaccinated mice presented clear brain affections and cutaneous diminishment of melanocytes. Therefore, these nanoparticle vaccines are effective measures to offer pregnant mothers at high risk of listeriosis interesting therapies that cross the placenta. Full article

(This article belongs to the Special Issue Nanoparticles in Immunology)

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1619 KiB

Open AccessReview

Recent Prospects in the Inline Monitoring of Nanocomposites and Nanocoatings by Optical Technologies

by Elodie Bugnicourt, Timothy Kehoe, Marcos Latorre, Cristina Serrano, Séverine Philippe and Markus Schmid

Nanomaterials 2016, 6(8), 150; https://doi.org/10.3390/nano6080150 - 19 Aug 2016

Cited by 28 | Viewed by 7778

Abstract

Nanostructured materials have emerged as a key research field in order to confer materials with unique or enhanced properties. The performance of nanocomposites depends on a number of parameters, but the suitable dispersion of nanoparticles remains the key in order to obtain the [...] Read more.

Nanostructured materials have emerged as a key research field in order to confer materials with unique or enhanced properties. The performance of nanocomposites depends on a number of parameters, but the suitable dispersion of nanoparticles remains the key in order to obtain the full nanocomposites’ potential in terms of, e.g., flame retardance, mechanical, barrier, thermal properties, etc. Likewise, the performance of nanocoatings to obtain, for example, tailored surface affinity with selected liquids (e.g., for self-cleaning ability or anti-fog properties), protective effects against flame propagation, ultra violet (UV) radiation or gas permeation, is highly dependent on the nanocoating’s thickness and homogeneity. In terms of recent advances in the monitoring of nanocomposites and nanocoatings, this review discusses commonly-used offline characterization approaches, as well as promising inline systems. All in all, having good control over both the dispersion and thickness of these materials would help with reaching optimal and consistent properties to allow nanocomposites to extend their use. Full article

(This article belongs to the Special Issue Nanocomposite Coatings)

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6229 KiB

Open AccessArticle

Receptor-Meditated Endocytosis by Hyaluronic Acid@Superparamagnetic Nanovetor for Targeting of CD44-Overexpressing Tumor Cells

by Kwang Sik Yu, Meng Meng Lin, Hyun-Ju Lee, Ki-Sik Tae, Bo-Sun Kang, Je Hun Lee, Nam Seob Lee, Young Gil Jeong, Seung-Yun Han and Do Kyung Kim

Nanomaterials 2016, 6(8), 149; https://doi.org/10.3390/nano6080149 - 18 Aug 2016

Cited by 14 | Viewed by 5439

Abstract

The present report proposes a more rational hyaluronic acid (HA) conjugation protocol that can be used to modify the surface of the superparamagnetic iron oxide nanoparticles (SPIONs) by covalently binding the targeting molecules (HA) with glutamic acid as a molecular linker on peripheral [...] Read more.

The present report proposes a more rational hyaluronic acid (HA) conjugation protocol that can be used to modify the surface of the superparamagnetic iron oxide nanoparticles (SPIONs) by covalently binding the targeting molecules (HA) with glutamic acid as a molecular linker on peripheral surface of SPIONs. The synthesis of HA-Glutamic Acid (GA)@SPIONs was included oxidization of nanoparticle’s surface with H₂O₂ followed by activation of hydroxyl group and reacting glutamic acid as an intermediate molecule demonstrating transfection of lung cancer cells. Fourier transform infrared (FTIR) and zeta-potential studies confirmed the chemical bonding between amino acid linker and polysaccharides. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity assay showed that HA-SPIONs-treated cells remained 82.9% ± 2.7% alive at high particle dosage (200 µg/mL iron concentration), whereas GA-SPIONs and bare SPIONs (B-SPIONs) treated cells had only 59.3% ± 13.4% and 26.5% ± 3.1% survival rate at the same conditions, respectively. Confocal microscopy analysis showed increased cellular internalization of HA-SPIONs compared to non-interacting agarose coated SPIONs (AgA-SPIONs). Full article

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3844 KiB

Open AccessArticle

Flexible Textile-Based Organic Transistors Using Graphene/Ag Nanoparticle Electrode

by Youn Kim, Yeon Ju Kwon, Kang Eun Lee, Youngseok Oh, Moon-Kwang Um, Dong Gi Seong and Jea Uk Lee

Nanomaterials 2016, 6(8), 147; https://doi.org/10.3390/nano6080147 - 16 Aug 2016

Cited by 20 | Viewed by 7510

Abstract

Highly flexible and electrically-conductive multifunctional textiles are desirable for use in wearable electronic applications. In this study, we fabricated multifunctional textile composites by vacuum filtration and wet-transfer of graphene oxide films on a flexible polyethylene terephthalate (PET) textile in association with embedding Ag [...] Read more.

Highly flexible and electrically-conductive multifunctional textiles are desirable for use in wearable electronic applications. In this study, we fabricated multifunctional textile composites by vacuum filtration and wet-transfer of graphene oxide films on a flexible polyethylene terephthalate (PET) textile in association with embedding Ag nanoparticles (AgNPs) to improve the electrical conductivity. A flexible organic transistor can be developed by direct transfer of a dielectric/semiconducting double layer on the graphene/AgNP textile composite, where the textile composite was used as both flexible substrate and conductive gate electrode. The thermal treatment of a textile-based transistor enhanced the electrical performance (mobility = 7.2 cm²·V⁻¹·s⁻¹, on/off current ratio = 4

\times

10⁵, and threshold voltage = −1.1 V) due to the improvement of interfacial properties between the conductive textile electrode and the ion-gel dielectric layer. Furthermore, the textile transistors exhibited highly stable device performance under extended bending conditions (with a bending radius down to 3 mm and repeated tests over 1000 cycles). We believe that our simple methods for the fabrication of graphene/AgNP textile composite for use in textile-type transistors can potentially be applied to the development of flexible large-area electronic clothes. Full article

(This article belongs to the Special Issue Textiles Nanotechnology)

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3686 KiB

Open AccessArticle

Methanol-Tolerant Platinum-Palladium Catalyst Supported on Nitrogen-Doped Carbon Nanofiber for High Concentration Direct Methanol Fuel Cells

by Jiyoung Kim, Jin-Sung Jang, Dong-Hyun Peck, Byungrok Lee, Seong-Ho Yoon and Doo-Hwan Jung

Nanomaterials 2016, 6(8), 148; https://doi.org/10.3390/nano6080148 - 15 Aug 2016

Cited by 17 | Viewed by 5315

Abstract

Pt-Pd catalyst supported on nitrogen-doped carbon nanofiber (N-CNF) was prepared and evaluated as a cathode electrode of the direct methanol fuel cell (DMFC). The N-CNF, which was directly synthesized by the catalytic chemical vapor deposition from acetonitrile at 640 °C, was verified as [...] Read more.

Pt-Pd catalyst supported on nitrogen-doped carbon nanofiber (N-CNF) was prepared and evaluated as a cathode electrode of the direct methanol fuel cell (DMFC). The N-CNF, which was directly synthesized by the catalytic chemical vapor deposition from acetonitrile at 640 °C, was verified as having a change of electrochemical surface properties such as oxygen reduction reaction (ORR) activities and the electrochemical double layer compared with common carbon black (CB). To attain the competitive oxygen reduction reaction activity with methanol tolerance, the Pt and Pd metals were supported on the CB or the N-CNF. The physical and electrochemical characteristics of the N-CNF–supported Pt-Pd catalyst were examined and compared with catalyst supported on the CB. In addition, DMFC single cells using these catalysts as the cathode electrode were applied to obtain I-V polarization curves and constant current operating performances with high-concentration methanol as the fuel. Pt-Pd catalysts had obvious ORR activity even in the presence of methanol. The higher power density was obtained at all the methanol concentrations when it applied to the membrane electrode assembly (MEA) of the DMFC. When the N-CNF is used as the catalyst support material, a better performance with high-concentration methanol is expected. Full article

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3893 KiB

Open AccessFeature PaperReview

Metallic Nanostructures Based on DNA Nanoshapes

by Boxuan Shen, Kosti Tapio, Veikko Linko, Mauri A. Kostiainen and Jari Jussi Toppari

Nanomaterials 2016, 6(8), 146; https://doi.org/10.3390/nano6080146 - 10 Aug 2016

Cited by 18 | Viewed by 8806

Abstract

Metallic nanostructures have inspired extensive research over several decades, particularly within the field of nanoelectronics and increasingly in plasmonics. Due to the limitations of conventional lithography methods, the development of bottom-up fabricated metallic nanostructures has become more and more in demand. The remarkable [...] Read more.

Metallic nanostructures have inspired extensive research over several decades, particularly within the field of nanoelectronics and increasingly in plasmonics. Due to the limitations of conventional lithography methods, the development of bottom-up fabricated metallic nanostructures has become more and more in demand. The remarkable development of DNA-based nanostructures has provided many successful methods and realizations for these needs, such as chemical DNA metallization via seeding or ionization, as well as DNA-guided lithography and casting of metallic nanoparticles by DNA molds. These methods offer high resolution, versatility and throughput and could enable the fabrication of arbitrarily-shaped structures with a 10-nm feature size, thus bringing novel applications into view. In this review, we cover the evolution of DNA-based metallic nanostructures, starting from the metallized double-stranded DNA for electronics and progress to sophisticated plasmonic structures based on DNA origami objects. Full article

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

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148 KiB

Open AccessEditorial

Nanostructured Solar Cells

by Guanying Chen, Zhijun Ning and Hans Ågren

Nanomaterials 2016, 6(8), 145; https://doi.org/10.3390/nano6080145 - 9 Aug 2016

Cited by 11 | Viewed by 6180

Abstract

We are glad to announce the Special Issue “Nanostructured Solar Cells”, published in Nanomaterials. This issue consists of eight articles, two communications, and one review paper, covering major important aspects of nanostructured solar cells of varying types. From fundamental physicochemical investigations to technological [...] Read more.

We are glad to announce the Special Issue “Nanostructured Solar Cells”, published in Nanomaterials. This issue consists of eight articles, two communications, and one review paper, covering major important aspects of nanostructured solar cells of varying types. From fundamental physicochemical investigations to technological advances, and from single junction solar cells (silicon solar cell, dye sensitized solar cell, quantum dots sensitized solar cell, and small molecule organic solar cell) to tandem multi-junction solar cells, all aspects are included and discussed in this issue to advance the use of nanotechnology to improve the performance of solar cells with reduced fabrication costs. Full article

(This article belongs to the Special Issue Nanostructured Solar Cells)

1585 KiB

Open AccessFeature PaperCommunication

Silicon Nanowire Photocathodes for Photoelectrochemical Hydrogen Production

by Soundarrajan Chandrasekaran, Thomas Nann and Nicolas H. Voelcker

Nanomaterials 2016, 6(8), 144; https://doi.org/10.3390/nano6080144 - 5 Aug 2016

Cited by 14 | Viewed by 5682

Abstract

The performance of silicon for water oxidation and hydrogen production can be improved by exploiting the antireflective properties of nanostructured silicon substrates. In this work, silicon nanowires were fabricated by metal-assisted electroless etching of silicon. An enhanced photocurrent density of −17 mA/cm² [...] Read more.

The performance of silicon for water oxidation and hydrogen production can be improved by exploiting the antireflective properties of nanostructured silicon substrates. In this work, silicon nanowires were fabricated by metal-assisted electroless etching of silicon. An enhanced photocurrent density of −17 mA/cm² was observed for the silicon nanowires coated with an iron sulphur carbonyl catalyst when compared to bare silicon nanowires (−5 mA/cm²). A substantial amount of 315 µmol/h hydrogen gas was produced at low bias potentials for the silicon nanowires coated with an iron sulphur carbonyl catalyst. Full article

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2748 KiB

Open AccessFeature PaperArticle

Distribution of Iron Oxide Core-Titanium Dioxide Shell Nanoparticles in VX2 Tumor Bearing Rabbits Introduced by Two Different Delivery Modalities

by Tamer Refaat, Derek West, Samar El Achy, Vamsi Parimi, Jasmine May, Lun Xin, Kathleen R. Harris, William Liu, Michael Beau Wanzer, Lydia Finney, Evan Maxey, Stefan Vogt, Reed A. Omary, Daniele Procissi, Andrew C. Larson, Tatjana Paunesku and Gayle E. Woloschak

Nanomaterials 2016, 6(8), 143; https://doi.org/10.3390/nano6080143 - 3 Aug 2016

Cited by 8 | Viewed by 6452

Abstract

This work compares intravenous (IV) versus fluoroscopy-guided transarterial intra-catheter (IC) delivery of iron oxide core-titanium dioxide shell nanoparticles (NPs) in vivo in VX2 model of liver cancer in rabbits. NPs coated with glucose and decorated with a peptide sequence from cortactin were administered [...] Read more.

This work compares intravenous (IV) versus fluoroscopy-guided transarterial intra-catheter (IC) delivery of iron oxide core-titanium dioxide shell nanoparticles (NPs) in vivo in VX2 model of liver cancer in rabbits. NPs coated with glucose and decorated with a peptide sequence from cortactin were administered to animals with developed VX2 liver cancer. Two hours after NPs delivery tumors, normal liver, kidney, lung and spleen tissues were harvested and used for a series on histological and elemental analysis tests. Quantification of NPs in tissues was done both by bulk inductively coupled plasma mass spectrometry (ICP-MS) analysis and by hard X-ray fluorescence microscopy. Both IV and IC NPs injection are feasible modalities for delivering NPs to VX2 liver tumors with comparable tumor accumulation. It is possible that this is an outcome of the fact that VX2 tumors are highly vascularized and hemorrhagic, and therefore enhanced permeability and retention (EPR) plays the most significant role in accumulation of nanoparticles in tumor tissue. It is, however, interesting to note that IV delivery led to increased sequestration of NPs by spleen and normal liver tissue, while IC delivery lead to more NP positive Kupffer cells. This difference is most likely a direct outcome of blood flow dynamics. Armed with this knowledge about nanoparticle delivery, we plan to test them as radiosensitizers in the future. Full article

(This article belongs to the Special Issue Nanomaterials for Cancer Therapies)

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3083 KiB

Open AccessFeature PaperReview

Review of Recent Developments on Using an Off-Lattice Monte Carlo Approach to Predict the Effective Thermal Conductivity of Composite Systems with Complex Structures

by Feng Gong, Hai M. Duong and Dimitrios V. Papavassiliou

Nanomaterials 2016, 6(8), 142; https://doi.org/10.3390/nano6080142 - 30 Jul 2016

Cited by 17 | Viewed by 5681

Abstract

Here, we present a review of recent developments for an off-lattice Monte Carlo approach used to investigate the thermal transport properties of multiphase composites with complex structure. The thermal energy was quantified by a large number of randomly moving thermal walkers. Different modes [...] Read more.

Here, we present a review of recent developments for an off-lattice Monte Carlo approach used to investigate the thermal transport properties of multiphase composites with complex structure. The thermal energy was quantified by a large number of randomly moving thermal walkers. Different modes of heat conduction were modeled in appropriate ways. The diffusive heat conduction in the polymer matrix was modeled with random Brownian motion of thermal walkers within the polymer, and the ballistic heat transfer within the carbon nanotubes (CNTs) was modeled by assigning infinite speed of thermal walkers in the CNTs. Three case studies were conducted to validate the developed approach, including three-phase single-walled CNTs/tungsten disulfide (WS₂)/(poly(ether ether ketone) (PEEK) composites, single-walled CNT/WS₂/PEEK composites with the CNTs clustered in bundles, and complex graphene/poly(methyl methacrylate) (PMMA) composites. In all cases, resistance to heat transfer due to nanoscale phenomena was also modeled. By quantitatively studying the influencing factors on the thermal transport properties of the multiphase composites, it was found that the orientation, aggregation and morphology of fillers, as well as the interfacial thermal resistance at filler-matrix interfaces would limit the transfer of heat in the composites. These quantitative findings may be applied in the design and synthesis of multiphase composites with specific thermal transport properties. Full article

(This article belongs to the Special Issue Computational Modeling and Simulations of Carbon Nanomaterials)

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3301 KiB

Open AccessArticle

Galactosylated Liposomes for Targeted Co-Delivery of Doxorubicin/Vimentin siRNA to Hepatocellular Carcinoma

by Hea Ry Oh, Hyun-Young Jo, James S. Park, Dong-Eun Kim, Je-Yoel Cho, Pyung-Hwan Kim and Keun-Sik Kim

Nanomaterials 2016, 6(8), 141; https://doi.org/10.3390/nano6080141 - 30 Jul 2016

Cited by 78 | Viewed by 8389

Abstract

The combination of therapeutic nucleic acids and chemotherapeutic drugs has shown great promise for cancer therapy. In this study, asialoglycoprotein receptors (ASGPR) targeting-ligand-based liposomes were tested to determine whether they can co-deliver vimentin siRNA and doxorubicin to hepatocellular carcinoma (HCC) selectively. To achieve [...] Read more.

The combination of therapeutic nucleic acids and chemotherapeutic drugs has shown great promise for cancer therapy. In this study, asialoglycoprotein receptors (ASGPR) targeting-ligand-based liposomes were tested to determine whether they can co-deliver vimentin siRNA and doxorubicin to hepatocellular carcinoma (HCC) selectively. To achieve this goal, we developed an ASGPR receptor targeted co-delivery system called gal-doxorubicin/vimentin siRNA liposome (Gal-DOX/siRNA-L). The Gal-DOX/siRNA-L was created via electrostatic interaction of galactose linked-cationic liposomal doxorubicin (Gal-DOX-L) on vimentin siRNA. Previous studies have shown that Gal-DOX/siRNA-L inhibited tumor growth by combined effect of DOX and vimentin siRNA than single delivery of either DOX or vimentin siRNA. These Gal-DOX/siRNA-Ls showed stronger affinity to human hepatocellular carcinoma cells (Huh7) than other cells (lung epithelial carcinoma, A549). These liposomes also have demonstrated that novel hepatic drug/gene delivery systems composed of cationic lipid (DMKE: O,O’-dimyristyl-N-lysyl glutamate), cholesterol, galactosylated ceramide, POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine), and PEG₂₀₀₀-DSPE (distearoyl phosphatidyl ethanolamine) at 2:1:1:1:0.2 (moral ratios) can be used as an effective drug/gene carrier specifically targeting the liver in vivo. These results suggest that Gal-DOX-siRNA-L could effectively target tumor cells, enhance transfection efficacy and subsequently achieve the co-delivery of DOX and siRNA, demonstrating great potential for synergistic anti-tumor therapy. Full article

(This article belongs to the Special Issue Nanomaterials for Tissue Engineering)

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5288 KiB

Open AccessArticle

Optoelectronic and Electrochemical Properties of Vanadium Pentoxide Nanowires Synthesized by Vapor-Solid Process

by Ko-Ying Pan and Da-Hua Wei

Nanomaterials 2016, 6(8), 140; https://doi.org/10.3390/nano6080140 - 29 Jul 2016

Cited by 35 | Viewed by 7042

Abstract

Substantial synthetic vanadium pentoxide (V₂O₅) nanowires were successfully produced by a vapor-solid (VS) method of thermal evaporation without using precursors as nucleation sites for single crystalline V₂O₅ nanowires with a (110) growth plane. The micromorphology and [...] Read more.

Substantial synthetic vanadium pentoxide (V₂O₅) nanowires were successfully produced by a vapor-solid (VS) method of thermal evaporation without using precursors as nucleation sites for single crystalline V₂O₅ nanowires with a (110) growth plane. The micromorphology and microstructure of V₂O₅ nanowires were analyzed by scanning electron microscope (SEM), energy-dispersive X-ray spectroscope (EDS), transmission electron microscope (TEM) and X-ray diffraction (XRD). The spiral growth mechanism of V₂O₅ nanowires in the VS process is proved by a TEM image. The photo-luminescence (PL) spectrum of V₂O₅ nanowires shows intrinsic (410 nm and 560 nm) and defect-related (710 nm) emissions, which are ascribable to the bound of inter-band transitions (V 3d conduction band to O 2p valence band). The electrical resistivity could be evaluated as 64.62 Ω·cm via four-point probe method. The potential differences between oxidation peak and reduction peak are 0.861 V and 0.470 V for the first and 10th cycle, respectively. Full article

(This article belongs to the Special Issue Nanomaterials for Flexible and Stretchable Devices: Synthesis, Processes, and Applications)

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2132 KiB

Open AccessFeature PaperReview

DNA-Based Enzyme Reactors and Systems

by Veikko Linko, Sami Nummelin, Laura Aarnos, Kosti Tapio, J. Jussi Toppari and Mauri A. Kostiainen

Nanomaterials 2016, 6(8), 139; https://doi.org/10.3390/nano6080139 - 27 Jul 2016

Cited by 63 | Viewed by 9423

Abstract

During recent years, the possibility to create custom biocompatible nanoshapes using DNA as a building material has rapidly emerged. Further, these rationally designed DNA structures could be exploited in positioning pivotal molecules, such as enzymes, with nanometer-level precision. This feature could be used [...] Read more.

During recent years, the possibility to create custom biocompatible nanoshapes using DNA as a building material has rapidly emerged. Further, these rationally designed DNA structures could be exploited in positioning pivotal molecules, such as enzymes, with nanometer-level precision. This feature could be used in the fabrication of artificial biochemical machinery that is able to mimic the complex reactions found in living cells. Currently, DNA-enzyme hybrids can be used to control (multi-enzyme) cascade reactions and to regulate the enzyme functions and the reaction pathways. Moreover, sophisticated DNA structures can be utilized in encapsulating active enzymes and delivering the molecular cargo into cells. In this review, we focus on the latest enzyme systems based on novel DNA nanostructures: enzyme reactors, regulatory devices and carriers that can find uses in various biotechnological and nanomedical applications. Full article

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

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3721 KiB

Open AccessArticle

Synthesis of p-Co₃O₄/n-TiO₂ Nanoparticles for Overall Water Splitting under Visible Light Irradiation

by Qiang Zhang, Zhenyin Hai, Aoqun Jian, Hongyan Xu, Chenyang Xue and Shengbo Sang

Nanomaterials 2016, 6(8), 138; https://doi.org/10.3390/nano6080138 - 27 Jul 2016

Cited by 29 | Viewed by 7493

Abstract

p-Co₃O₄/n-TiO₂ nanoparticles (~400 nm) for photocatalysis were prepared via carbon assisted method and sol-gel method in this work. The paper also studied the application of visible light illuminated p-Co₃O₄/n-TiO₂ nanocomposites cocatalyst to the [...] Read more.

p-Co₃O₄/n-TiO₂ nanoparticles (~400 nm) for photocatalysis were prepared via carbon assisted method and sol-gel method in this work. The paper also studied the application of visible light illuminated p-Co₃O₄/n-TiO₂ nanocomposites cocatalyst to the overall pure water splitting into H₂ and O₂. In addition, the H₂ evolution rate of the p-Co₃O₄/n-TiO₂ nanocomposites is 25% higher than that of the pure Co₃O₄ nanoparticles. Besides, according to the results of the characterizations, the scheme of visible light photocatalytic water splitting is proposed, the Co₃O₄ of the nanocomposites is excited by visible light, and the photo-generated electrons and holes existing on the conduction band of Co₃O₄ and valence band of TiO₂ have endowed the photocatalytic evolution of H₂ and O₂ with higher efficiency. The optimal evolution rate of H₂ and O₂ is 8.16 μmol/h·g and 4.0 μmol/h·g, respectively. Full article

(This article belongs to the Special Issue Nanoscale in Photocatalysis)

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5121 KiB

Open AccessFeature PaperArticle

Green Synthesis of Hierarchically Structured Silver-Polymer Nanocomposites with Antibacterial Activity

by María Jesús Hortigüela, Luis Yuste, Fernando Rojo and Inmaculada Aranaz

Nanomaterials 2016, 6(8), 137; https://doi.org/10.3390/nano6080137 - 25 Jul 2016

Cited by 13 | Viewed by 6512

Abstract

The in situ formation of silver nanoparticles (AgNPs) aided by chondroitin sulfate and the preparation of a hierarchically structured silver-polymer nanocomposite with antimicrobial activity is shown. Green synthesis of AgNPs is carried out by thermal treatment (80 and 90 °C) or UV irradiation [...] Read more.

The in situ formation of silver nanoparticles (AgNPs) aided by chondroitin sulfate and the preparation of a hierarchically structured silver-polymer nanocomposite with antimicrobial activity is shown. Green synthesis of AgNPs is carried out by thermal treatment (80 and 90 °C) or UV irradiation of a chondroitin sulfate solution containing AgNO₃ without using any further reducing agents or stabilizers. Best control of the AgNPs size and polydispersity was achieved by UV irradiation. The ice-segregation-induced self-assembly (ISISA) process, in which the polymer solution containing the AgNPs is frozen unidirectionally, and successively freeze-drying were employed to produce the chondroitin sulfate 3D scaffolds. The scaffolds were further crosslinked with hexamethylene diisocyanate vapors to avoid water solubility of the 3D structures in aqueous environments. The antimicrobial activity of the scaffolds was tested against Escherichia coli. The minimum inhibitory concentration (MIC) found for AgNPs-CS (chondroitin sulfate) scaffolds was ca. 6 ppm. Full article

(This article belongs to the Special Issue Polysaccharide-Based Nanosorbent Materials: Fundamental Science and Beyond)

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