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Yao Chen, Mengjiao Xu, Yi Guo, Keyao Tu, Weimin Wu, Jianjun Wang, Xiaowen Tong, Wenjuan Wu, Lifeng Qi, Donglu Shi
Efficient delivery of small interfering RNAs (siRNAs) to the targeted cells has remained a significant challenge in clinical applications. In the present study, we developed a novel aptamer-siRNA chimera delivery system mediated by cationic Au-Fe3O4 nanoparticles (NPs). The chimera constructed by VEGF RNA aptamer and Notch3 siRNA was bonded with heterogeneous Au-Fe3O4 nanoparticles by electrostatic interaction. The obtained complex exhibited much higher silencing efficiency against Notch3 gene compared with chimera alone and lipofectamine-siRNA complex, and improved the antitumor effects of the loaded chimera...
December 1, 2016: Nanotechnology
Sagnik Basuray, Avinash Pathak, Sangho Bok, Biyan Chen, Steven C Hamm, Cherian J Mathai, Suchismita Guha, Keshab Gangopadhyay, Shubhra Gangopadhyay
Classical methods for enhancing the electromagnetic field from substrates for spectroscopic applications, such as surface-enhanced Raman spectroscopy (SERS), have involved the generation of hotspots through directed self-assembly of nanoparticles or by patterning nanoscale features using expensive nanolithography techniques. A novel large-area, cost-effective soft lithographic technique involving glancing angle deposition (GLAD) of silver on polymer gratings is reported here. This method produces hierarchical nanostructures with high enhancement factors capable of analyzing single-molecule SERS...
December 1, 2016: Nanotechnology
Shital Patangrao Pawar, Sachin Kumar, Shubham Jain, Mounika Gandi, Kaushik Chatterjee, Suryasarathi Bose
The need of today's highly integrated electronic devices, especially working in the GHz frequencies, is to protect them from unwanted interference from neighbouring devices. Hence, lightweight, flexible, easy to process microwave absorbers were designed here by dispersing conductive multiwall carbon nanotubes (MWNTs) and silver nanoparticles decorated onto two-dimensional graphene sheets (rGO@Ag) in poly(ε-caprolactone) (PCL). In this study, we have shown how dielectric losses can be tuned in the nanocomposites by rGO@Ag nano-hybrid; an essential criterion for energy dissipation within a material resulting in effective shielding of the incoming electromagnetic (EM) radiation...
December 1, 2016: Nanotechnology
Mohsen Nami, Rhett F Eller, Serdal Okur, Ashwin K Rishinaramangalam, Sheng Liu, Igal Brener, Daniel F Feezell
Controlled bottom-up selective-area epitaxy (SAE) is used to tailor the morphology and photoluminescence properties of GaN/InGaN core-shell nanowire arrays. The nanowires are grown on c-plane sapphire substrates using pulsed-mode metal organic chemical vapor deposition. By varying the dielectric mask configuration and growth conditions, we achieve GaN nanowire cores with diameters ranging from 80 to 700 nm that exhibit various degrees of polar, semipolar, and nonpolar faceting. A single InGaN quantum well (QW) and GaN barrier shell is also grown on the GaN nanowire cores and micro-photoluminescence is obtained and analyzed for a variety of nanowire dimensions, array pitch spacings, and aperture diameters...
December 1, 2016: Nanotechnology
Semra Senturk-Ozer, Seda Aktas, Jing He, Frank T Fisher, Dilhan M Kalyon
Non-woven nanoporous membranes of poly(caprolactone), PCL, incorporated with multi-walled carbon nanotubes, CNTs, could be fabricated via an industrially-scalable hybrid twin screw extrusion and electrospinning process. The utilization of a spinneret with multiple nozzles allowed the increase of the flow rate beyond what is possible with conventional electrospinning using a single nozzle, albeit at the expense of difficulties in the control of the thickness distributions of the nanofibrous membranes. The thickness and orientation distributions and the resulting mechanical properties of the membranes could be modified via changes in voltage, angular velocity of the collector mandrel and separation distance of the collector from the spinneret...
December 1, 2016: Nanotechnology
Bingrong Wang, Yang Cao, Yong Chen, Xiaoyong Lai, Juan Peng, Jinchun Tu, Xiaotian Li
NiCo2O4 nanospheres, a type of conjugated reduced graphene oxide (rGO), are compounded by a simple and easy synthesis of Cu2O/GO and fabricated NiCo2O4/rGO nanocomposites based on a Cu2O/GO template. The structure and morphology of the hierarchical NiCo2O4/rGO are characterized by x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The electrochemistry properties of NiCo2O4/rGO composites toward glucose are determined based on a glassy carbon electrode, and the results indicate that the hollow nanospheres of NiCo2O4/rGO could achieve high-sensitivity detections of glucose...
December 1, 2016: Nanotechnology
Hongsik Byun, Jiayun Hu, Phakkhananan Pakawanit, Laongnuan Srisombat, Jun-Hyun Kim
The in situ formation of dielectric silica (SiO2) particles was carried out in the presence of temperature-responsive poly(N-isopropylacrylamide) particles. Unlike the typical sol-gel method used to prepare various SiO2 particles, the highly uniform growth of SiO2 particles was achieved within the cross-linked polymer particles (i.e., the polymer particles were filled with the SiO2 particles) simply by utilizing interfacial interactions, including the van der Waals attractive force and hydrogen bonding in nanoscale environments...
December 1, 2016: Nanotechnology
Xiaoli Hu, Nicholas Chan, Ashlie Martini, Philip Egberts
Amplitude modulated atomic force microscopy (AM-AFM) was used to examine the influence of the size of the AFM tip apex on the measured surface topography of single highly oriented pyrolytic graphite (HOPG) atomic steps. Experimental measurements were complemented by molecular dynamics simulations of AM-AFM and the results from both were evaluated by comparison of the measured or simulated width of the topography at the step to that predicted using simple rigid-body geometry. The results showed that the step width, which is a reflection of the resolution of the measurement, increased with tip size, as expected, but also that the difference between the measured/simulated step width and the geometric calculation was tip size dependent...
December 1, 2016: Nanotechnology
S Gies, B Holz, C Fuchs, W Stolz, W Heimbrodt
(Ga,In)As/GaAs/Ga(As,Sb) multi-quantum well heterostructures have been investigated using continuous wave and time-resolved photoluminescence spectroscopy at various temperatures. A complex interplay was observed between the excitonic type-II transitions with electrons in the (Ga,In)As well and holes in the Ga(As,Sb) well and the type-I excitons in the (Ga,In)As and Ga(As,Sb) wells. The type-II luminescence exhibits a strongly non-exponential temporal behavior below a critical temperature of T c = 70 K. The transients were analyzed in the framework of a rate-equation model...
December 1, 2016: Nanotechnology
Aiva Simaite, Aude Delagarde, Bertrand Tondu, Philippe Souères, Emmanuel Flahaut, Christian Bergaud
During cyclic actuation, conducting polymer based artificial muscles are often creeping from the initial movement range. One of the likely reasons of such behaviour is unbalanced charging during conducting polymer oxidation and reduction. To improve the actuation reversibility and subsequently the long time performance of ionic actuators, we suggest using spray-coated carbon nanotube (CNT) carpets on the surface of the conducting polymer electrodes. We show that carbon nanotubes facilitate a conducting polymer redox reaction and improve its reversibility...
December 1, 2016: Nanotechnology
Shuwen Zhao, Donglin Xia, Ruimin Zhao, Hao Zhu, Yiru Zhu, Yuda Xiong, Youfa Wang
Hexagonal-phase NaGdF4: Yb, Er upconversion nanocrystals (UCNCs) with tunable morphology and properties were successfully prepared via a thermal decomposition method. The influences of the adding sequence of the precursors on the morphology, chemical composition, luminescence and magnetic properties were investigated by transmission electron microscopy (TEM), inductively coupled plasma-atomic emission spectrometry (ICP-AES), upconversion (UC) spectroscopy, and a vibrating sample magnetometer (VSM). It was found that the resulting nanocrystals, with different sizes ranging from 24 to 224 nm, are in the shape of spheres,  hexagonal plates and flakes; moreover, the composition percentage of Yb(3+)-Er(3+) and Gd(3+) ions was found to vary in a regular pattern with the adding sequence...
November 30, 2016: Nanotechnology
Whitney Ingram, Steven Larson, Daniel Carlson, Yiping Zhao
By combining shadow nanosphere lithography with a glancing angle co-deposition technique, mixed-phase Ag-Cu triangular nanopatterns and films were fabricated. They were prepared at different compositions with respect to Ag from 100% to 0% by changing the relative deposition ratio of each metal. Characterizations by ellipsometry, energy dispersive x-ray spectroscopy, and x-ray diffraction revealed that the thin films and nanopatterns were composed of small, well-mixed Ag and Cu nano-grains with a diameter less than 20 nm, and their optical properties could be described by an effective medium theory...
November 29, 2016: Nanotechnology
Jonas Nyvold Pedersen, Paul Boynton, Massimiliano Di Ventra, Antti-Pekka Jauho, Henrik Flyvbjerg
It has been theoretically suggested and experimentally demonstrated that fast and low-cost sequencing of DNA, RNA, and peptide molecules might be achieved by passing such molecules between electrodes embedded in a nanochannel. The experimental realization of this scheme faces major challenges, however. In realistic liquid environments, typical currents in tunneling devices are of the order of picoamps. This corresponds to only six electrons per microsecond, and this number affects the integration time required to do current measurements in real experiments...
November 29, 2016: Nanotechnology
Celia Castro, Gérard BenAssayag, Béatrice Pecassou, Andrea Andreozzi, Gabriele Seguini, Michele Perego, Sylvie Schamm-Chardon
In this work, we investigate the ability to control Si nanoparticles (NPs) spatially arranged in a hexagonal network of 20 nm wide nanovolumes at controlled depth within SiO2 thin films. To achieve this goal an unconventional lithographic technique was implemented based on a bottom-up approach, that is fully compatible with the existing semiconductor technology. The method combines ultra-low energy ion beam synthesis with nanostructured block-copolymer thin films that are self-assembled on the SiO2 substrates to form a nanoporous template with hexagonally packed pores...
November 29, 2016: Nanotechnology
Alfred J Baca, Heather A Meylemans, Lawrence Baldwin, Lee R Cambrea, Ji Feng, Yadong Yin, M Joseph Roberts
AgInS2 (AIS) quantum dots (QDs) were synthesized via a thermal decomposition reaction with dodecylamine as the ligand to help stabilize the QDs. This reaction procedure is relatively easy to implement, scalable to large batches (up to hundreds of milligrams of QDs are produced), and a convenient method for the synthesis of chalcogenide QDs. Metal powders of AgNO3 and In(NO3)3, were used as the metal precursors while diethyldithiocarbamate was used as the sulfur source. The AIS QDs were characterized via transmission electron microscopy, atomic force microscopy, and energy dispersive x-ray spectroscopy...
November 29, 2016: Nanotechnology
Daniele Barettin, Matthias Auf der Maur, Aldo di Carlo, Alessandro Pecchia, Andrei F Tsatsulnikov, Alexei V Sakharov, Wsevolod V Lundin, Andrei E Nikolaev, Sergey O Usov, Nikolay Cherkashin, Martin J Hÿtch, Sergey Yu Karpov
The impact of electromechanical coupling on optical properties of light-emitting diodes (LEDs) with InGaN/GaN quantum-dot (QD) active regions is studied by numerical simulations. The structure, i.e. the shape and the average In content of the QDs, has been directly derived from experimental data on out-of-plane strain distribution obtained from the geometric-phase analysis of a high-resolution transmission electron microscopy image of an LED structure grown by metalorganic vapor-phase epitaxy. Using continuum [Formula: see text] calculations, we have studied first the lateral and full electromechanical coupling between the QDs in the active region and its impact on the emission spectrum of a single QD located in the center of the region...
November 29, 2016: Nanotechnology
Seung-Yeol Jeon, Jinhyeok Jang, Bon-Woong Koo, Young-Woon Kim, Woong-Ryeol Yu
Due to the outstanding mechanical properties of individual carbon nanotubes (CNTs) at the nanoscale, CNT yarns are expected to demonstrate high strength at the macroscale. In this study, a predictable model was developed to predict the tensile strength of twisted CNT yarns. First, the failure mechanism of twisted CNT yarns was investigated using in situ tensile tests and ex situ observations. It was revealed that CNT bundles, which are groups of CNTs that are tightly bound together, formed during tensile loading, leaving some voids around the bundles...
November 29, 2016: Nanotechnology
Jungdong Kim, Hak-Young Ahn, Seung Gi Kim, Eunsoon Oh, Byeong-Kwon Ju, Won Jun Choi, So-Hye Cho
We studied temperature-dependent photoluminescence (PL) spectra of lead selenide (PbSe) dendrites and cubes grown by a solvothermal method. Their PL peaks were located at ∼8 μm at 10 K with a full width at half maximum (FWHM) of 10 meV. Using the temperature-dependent FWHM values, we obtained carrier-phonon coupling coefficients for PbSe. We also demonstrated mechanochemical synthesis of polycrystalline PbS nanoparticles and their successful conversion into a PbSe layer composed of nanocrystals by a selenization process with thermal treatment...
November 29, 2016: Nanotechnology
Md Mehebub Alam, Sujoy Kumar Ghosh, Debabrata Sarkar, Shrabanee Sen, Dipankar Mandal
Titanium dioxide (TiO2) nanoparticles (NPs) embedded γ-phase containing polyvinylidene fluoride (PVDF) nanocomposite (PNC) film turns to an excellent material for energy storage application due to an increased dielectric constant (32 at 1 kHz), enhanced electric breakdown strength (400 MV m(-1)). It also exhibits a high energy density of 4 J cm(-3) which is 25 times higher than that of virgin PVDF. 98% of the electroactive γ-phase has been acheived by the incorporation of TiO2 NPs and the resulting PNC behaves like a super-toughened material due to a dramatic improvement (more than 80%) in the tensile strength...
November 29, 2016: Nanotechnology
Dhritiman Bhattacharya, Md Mamun Al-Rashid, Noel D'Souza, Supriyo Bandyopadhyay, Jayasimha Atulasimha
Micromagnetic studies of the magnetization change in magnetostrictive nanomagnets subjected to stress are performed for nanomagnets of different sizes. The interplay between demagnetization, exchange and stress anisotropy energies is used to explain the rich physics of size-dependent magnetization dynamics induced by modulating stress anisotropy in planar nanomagnets. These studies have important implications for strain mediated ultralow energy magnetization control in nanomagnets and its application in energy-efficient nanomagnetic computing devices...
November 28, 2016: Nanotechnology
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