pinecone/core-2020-05-10-deduplication huggingface dataset:
Plasmonic enhancement in BiVO4 photonic crystals for efficient water splitting

Photo-electrochemical water splitting is a very promising and environmentally friendly route for the conversion of solar energy into hydrogen. However, the solar-to-H2 conversion efficiency is still very low due to rapid bulk recombination of charge carriers. Here, a photonic nano-architecture is developed to improve charge carrier generation and separation by manipulating and confining light absorption in a visible-light-active photoanode constructed from BiVO4 photonic crystal and plasmonic nanostructures. Synergistic effects of photonic crystal stop bands and plasmonic absorption are observed to operate in this photonic nanostructure. Within the scaffold of an inverse opal photonic crystal, the surface plasmon resonance is significantly enhanced by the photonic Bragg resonance. Nanophotonic photoanodes show AM 1.5 photocurrent densities of 3.1 ± 0.1 mA cm-2 at 1.23 V versus RHE, which is among the highest for oxide-based photoanodes and over 4 times higher than the unstructured planar photoanode
Coherent spin transport and suppression of spin relaxation in InSb
  nanowires with single subband occupancy at room temperature

A longstanding goal of spintronics is to inject, coherently transport, and
detect spins in a semiconductor nanowire where a SINGLE quantized subband is
occupied at room temperature. Here, we report achieving this goal in 50-nm
diameter InSb nanowires by demonstrating both the spin-valve and the Hanle
effect. The spin relaxation time in the nanowires was found to have increased
by an order of magnitude over what has been reported in bulk and quantum wells
due to the suppression of D'yakonov-Perel' spin relaxation as a result of
single subband occupancy. These experiments raise hopes for the realization of
a room-temperature Datta-Das spin transistor
Manganese Doped Fluorescent Paramagnetic Nanocrystals for Dual-Modal Imaging

Cataloged from PDF version of article.In this work, dual-modal (fluorescence and magnetic resonance) imaging capabilities of water-soluble, low-toxicity, monodisperse Mn-doped ZnSe nanocrystals (NCs) with a size (6.5 nm) below the optimum kidney cutoff limit (10 nm) are reported. Synthesizing Mn-doped ZnSe NCs with varying Mn2+ concentrations, a systematic investigation of the optical properties of these NCs by using photoluminescence (PL) and time resolved fluorescence are demonstrated. The elemental properties of these NCs using X-ray photoelectron spectroscopy and inductive coupled plasma-mass spectroscopy confirming Mn2+ doping is confined to the core of these NCs are also presented. It is observed that with increasing Mn2+ concentration the PL intensity first increases, reaching a maximum at Mn2+ concentration of 3.2 at% (achieving a PL quantum yield (QY) of 37%), after which it starts to decrease. Here, this high-efficiency sample is demonstrated for applications in dual-modal imaging. These NCs are further made water-soluble by ligand exchange using 3-mercaptopropionic acid, preserving their PL QY as high as 18%. At the same time, these NCs exhibit high relaxivity (≈2.95 mM-1 s-1) to obtain MR contrast at 25°C, 3 T. Therefore, the Mn2+ doping in these water-soluble Cd-free NCs are sufficient to produce contrast for both fluorescence and magnetic resonance imaging techniques. © 2014 Wiley-VCH Verlag GmbH & Co. KGaA
Stochastic Particle Barcoding for Single-Cell Tracking and Multiparametric Analysis

This study presents stochastic particle barcoding (SPB), a method for tracking cell identity across bioanalytical platforms. In this approach, single cells or small collections of cells are co-encapsulated within an enzymatically-degradable hydrogel block along with a random collection of fluorescent beads, whose number, color, and position encode the identity of the cell, enabling samples to be transferred in bulk between single-cell assay platforms without losing the identity of individual cells. The application of SPB is demonstrated for transferring cells from a subnanoliter protein secretion/phenotyping array platform into a microtiter plate, with re-identification accuracies in the plate assay of 96±2%. Encapsulated cells are recovered by digesting the hydrogel, allowing subsequent genotyping and phenotyping of cell lysates. Finally, a model scaling is developed to illustrate how different parameters affect the accuracy of SPB and to motivate scaling of the method to thousands of unique blocks.Ragon Institute of MGH, MIT and HarvardNational Cancer Institute (U.S.) (Koch Institute Support (Core) Grant P30-CA14051)National Institutes of Health (U.S.). Ruth L. Kirschstein National Research Service Award (1F32CA180586
In vivo Gold Nanoparticle Delivery of Peptide Vaccine Induces Anti-Tumor Immune Response in Prophylactic and Therapeutic Tumor Models

Gold nanoparticles (AuNPs) are promising vehicles for cancer immunotherapy, with demonstrated efficacy in immune delivery and innate cell stimulation. Nevertheless, their potential has yet to be assessed in the in vivo application of peptide cancer vaccines. In this study, it is hypothesized that the immune distribution and adjuvant qualities of AuNPs could be leveraged to facilitate delivery of the ovalbumin (OVA) peptide antigen and the CpG adjuvant and enhance their therapeutic effect in a B16-OVA tumor model. AuNP delivery of OVA (AuNP-OVA) and of CpG (AuNP-CpG) enhanced the efficacy of both agents and induced strong antigen-specific responses. In addition, it is found that AuNP-OVA delivery alone, without CpG, is sufficient to promote significant antigen-specific responses, leading to subsequent anti-tumor activity and prolonged survival in both prophylactic and therapeutic in vivo tumor models. This enhanced therapeutic efficacy is likely due to the adjuvant effect of peptide coated AuNPs, as they induce inflammatory cytokine release when cultured with bone marrow dendritic cells. Overall, AuNP-mediated OVA peptide delivery can produce significant therapeutic benefits without the need of adjuvant, indicating that AuNPs are effective peptide vaccine carriers with the potential to permit the use of lower and safer adjuvant doses during vaccination
Self-Aligned Colloidal Lithography for Controllable and Tuneable Plasmonic Nanogaps

Au nanoparticles (NPs) deposited on a substrate function as ring shaped colloidal shadow masks. Using e-beam evaporation of gold, nanometer sized gaps are formed as a result. The size of these gaps can be accurately tuned by controlling the thickness of the gold deposition, thereby tuning the plasmonic coupling of the NPs with the substrate. The clean cavity produced between the Au NPs and the Au film provides an excellent SERS platform for trace molecule detection.The authors acknowledge the ﬁ nancial support of this research from EPSRC grant EP/G060649/1, EP/I012060/1, and ERC grant LINASS 320503. FB acknowledges support from the Winton Pro-gramme for the Physics of Sustainability.This article was originally published in Small, 2015, DOI: 10.1002/smll.201402639
Development of a High-Throughput Functional Screen Using Nanowell-Assisted Cell Patterning

Living-cell-based screens can facilitate lead discovery of functional therapeutics of interest. A versatile and scalable method is reported that uses dense arrays of nanowells for imparting defined patterns on monolayers of cells. It is shown that this approach can coordinate a multi-component biological assay by designing and implementing a high-throughput, functional nanoliter-scale neutralization assay to identify neutra­lizing antibodies against HIV.National Cancer Institute (U.S.) (P30-CA14051
Magnetic Force Microscopy in Liquids

This is the peer reviewed version of the following article:Small 11.36 (2015): 4731-4736, which has been published in final form at http://dx.doi.org/10.1002/smll.201500874. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-ArchivingIn this work, the use of magnetic force microscopy (MFM) to acquire images of magnetic nanostructures in liquid environments is presented. Optimization of the MFM signal acquisition in liquid media is performed and it is applied to characterize the magnetic signal of magnetite nanoparticles. The ability for detecting magnetic nanostructures along with the well-known capabilities of atomic force microscopy in liquids suggests potential applications in fields such as nanomedicine, nanobiotechnology, or nanocatalysis. Magnetic force microscopy (MFM) in liquids is presented. Magnetic contrast in different media is studied and optimized for liquids. MFM is successfully applied to the study of magnetite nanoparticles. The ability of measuring magnetic nanostructures along with the well-known capabilities of atomic force microscopy in liquids suggests new strategies in the characterization of relevant systems in fields such as nanomedicine, biology, or nanocatalysisThis work was supported by Consolider CSD2010-0024, MAT2013-46753-C2-2-P and MAT2013-48054-C2-1 project
Simultaneous or Sequential Orthogonal Gradient Formation in a 3D Cell Culture Microfluidic Platform

Biochemical gradients are ubiquitous in biology. At the tissue level, they dictate differentiation patterning or cell migration. Recapitulating in vitro the complexity of such concentration profiles with great spatial and dynamic control is crucial in order to understand the underlying mechanisms of biological phenomena. Here, a microfluidic design capable of generating diffusion-driven, simultaneous or sequential, orthogonal linear concentration gradients in a 3D cell-embedded scaffold is described. Formation and stability of the orthogonal gradients are demonstrated by computational and fluorescent dextran-based characterizations. Then, system utility is explored in two biological systems. First, stem cells are subjected to orthogonal gradients of morphogens in order to mimic the localized differentiation of motor neurons in the neural tube. Similarly to in vivo, motor neurons preferentially differentiate in regions of high concentration of retinoic acid and smoothened agonist (acting as sonic hedgehog), in a concentration-dependent fashion. Then, a rotating gradient is applied to HT1080 cancer cells and the change in migration direction is investigated as the cells adapt to a new chemical environment. The response time of ≈4 h is reported. These two examples demonstrate the versatility of this new design that can also prove useful in many applications including tissue engineering and drug screening.National Science Foundation. Science and Technology Center for Emergent Behaviors of Integrated Cellular Systems (Grant No. CBET-0939511)National Institutes of Health (U.S.) (NIH NRSA/UNCF Merck
Magnetic bead/gold nanoparticle double-labeled primers for electrochemical detection of isothermal amplified Leishmania DNA

A novel methodology for the isothermal amplification of Leishmania DNA using labeled primers combined with the advantages of magnetic purification/preconcentration and the use of gold nanoparticle (AuNP) tags for the sensitive electrochemical detection of such amplified DNA is developed. Primers labeled with AuNPs and magnetic beads (MBs) are used for the first time for the isothermal amplification reaction, being the amplified product ready for the electrochemical detection. The electrocatalytic activity of the AuNP tags toward the hydrogen evolution reaction allows the rapid quantification of the DNA on screen-printed carbon electrodes. Amplified products from the blood of dogs with Leishmania (positive samples) are discriminated from those of healthy dogs (blank samples). Quantitative studies demonstrate that the optimized method allows us to detect less than one parasite per microliter of blood (8 × 10⁻³ parasites in the isothermal amplification reaction). This pioneering approach is much more sensitive than traditional methods based on real-time polymerase chain reaction (PCR), and is also more rapid, cheap, and user-friendly
Nanoscale Plasmon-Enhanced Spectroscopy in Memristive Switches

Resistive switching memories are nonvolatile memory cells based on nano-ionic redox processes and offer prospects for high scalability, ultrafast write and read access, and low power consumption. In two-terminal cation based devices a nanoscale filament is formed in a switching material by metal ion migration from the anode to the cathode. However, the filament growth and dissolution mechanisms and the dynamics involved are still open questions, restricting device optimization. Here, a spectroscopic technique to optically characterize in situ the resistive switching effect is presented. Resistive switches arranged in a nanoparticle-on-mirror geometry are developed, exploiting the high sensitivity to morphological changes occurring in the tightly confined plasmonic hotspot within the switching material. The focus is on electrochemical metallization and the optical signatures detected over many cycles indicate incomplete removal of metal particles from the filament upon RESET and suggest that the filament can nucleate from different positions from cycle to cycle. The technique here is nondestructive and the measurements can be easily performed in tunable ambient conditions and with realistic cell geometries.G.D.M. and S.T. contributed equally to this work. The authors acknowledge Alan Sanders for developing the data collection software and Richard Bowman for providing part of the experimental equipment. The authors acknowledge funding from ERC grant LINASS 320503, EPSRC grant EP/L027151/1, and ERC grant InsituNANO 279342.This is the final version of the article. It first appeared from Wiley via https://doi.org/10.1002/smll.20150316
Identification of individual exosome-like vesicles by surface enhanced Raman spectroscopy

Exosome-like vesicles (ELVs) are a novel class of biomarkers that are receiving a lot of attention for the detection of cancer at an early stage. In this study the feasibility of using a surface enhanced Raman spectroscopy (SERS) based method to distinguish between ELVs derived from different cellular origins is evaluated. A gold nanoparticle based shell is deposited on the surface of ELVs derived from cancerous and healthy cells, which enhances the Raman signal while maintaining a colloidal suspension of individual vesicles. This nanocoating allows the recording of SERS spectra from single vesicles. By using partial least squares discriminant analysis on the obtained spectra, vesicles from different origin can be distinguished, even when present in the same mixture. This proof-of-concept study paves the way for noninvasive (cancer) diagnostic tools based on exosomal SERS fingerprinting in combination with multivariate statistical analysis
Electronic Activation of a DNA Nanodevice Using a Multilayer Nanofilm

A method to control activation of a DNA nanodevice by supplying a complementary\ud
DNA (cDNA) strand from an electro-responsive nanoplatform is reported. To develop\ud
functional nanoplatform, hexalayer nanofilm is precisely designed by layer-by-layer\ud
assembly technique based on electrostatic interaction with four kinds of materials:\ud
Hydrolyzed poly(β-amino ester) can help cDNA release from the film. A cDNA is\ud
used as a key building block to activate DNA nanodevice. Reduced graphene oxides\ud
(rGOs) and the conductive polymer provide conductivity. In particular, rGOs efficiently\ud
incorporate a cDNA in the film via several interactions and act as a barrier. Depending\ud
on the types of applied electronic stimuli (reductive and oxidative potentials), a\ud
cDNA released from the electrode can quantitatively control the activation of DNA\ud
nanodevice. From this report, a new system is successfully demonstrated to precisely\ud
control DNA release on demand. By applying more advanced form of DNA-based\ud
nanodevices into multilayer system, the electro-responsive nanoplatform will expand\ud
the availability of DNA nanotechnology allowing its improved application in areas\ud
such as diagnosis, biosensing, bioimaging, and drug delivery
Magnetometry of individual polycrystalline ferromagnetic nanowires

Ferromagnetic nanowires are finding use as untethered sensors and actuators for probing micro- and nanoscale biophysical phenomena, such as for localized sensing and application of forces and torques on biological samples, for tissue heating through magnetic hyperthermia, and for micro-rheology. Quantifying the magnetic properties of individual isolated nanowires is crucial for such applications. We use dynamic cantilever magnetometry to measure the magnetic properties of individual sub-500nm diameter polycrystalline nanowires of Ni and Ni80Co20 fabricated by template-assisted electrochemical deposition. The values are compared with bulk, ensemble measurements when the nanowires are still embedded within their growth matrix. We find that single-particle and ensemble measurements of nanowires yield significantly different results that reflect inter-nanowire interactions and chemical modifications of the sample during the release process from the growth matrix. The results highlight the importance of performing single-particle characterization for objects that will be used as individual magnetic nanoactuators or nanosensors in biomedical applications
Growing oxide nanowires and nanowire networks by solid state contact diffusion into solution‐processed thin films

New techniques to directly grow metal oxide nanowire networks without the need for initial nanoparticle seed deposition or postsynthesis nanowire casting will bridge the gap between bottom‐up formation and top‐down processing for many electronic, photonic, energy storage, and conversion technologies. Whether etched top‐down, or grown from catalyst nanoparticles bottom‐up, nanowire growth relies on heterogeneous material seeds. Converting surface oxide films, ubiquitous in the microelectronics industry, to nanowires and nanowire networks by the incorporation of extra species through interdiffusion can provide an alternative deposition method. It is shown that solution‐processed thin films of oxides can be converted and recrystallized into nanowires and networks of nanowires by solid‐state interdiffusion of ionic species from a mechanically contacted donor substrate. NaVO3 nanowire networks on smooth Si/SiO2 and granular fluorine‐doped tin oxide surfaces can be formed by low‐temperature annealing of a Na diffusion species‐containing donor glass to a solution‐processed V2O5 thin film, where recrystallization drives nanowire growth according to the crystal habit of the new oxide phase. This technique illustrates a new method for the direct formation of complex metal oxide nanowires on technologically relevant substrates, from smooth semiconductors, to transparent conducting materials and interdigitated device structures
Lateral Magnetically Modulated Multilayers by Combining Ion Implantation and Lithography

Altres ajuts: Research Foundation-Flanders (FWO) Fonds Wetenschappelijk Onderzoek, the Concerted Research Action GOA/14/007.The combination of lithography and ion implantation is demonstrated to be a suitable method to prepare lateral multilayers. A laterally, compositionally, and magnetically modulated microscale pattern consisting of alternating Co (1.6 µm wide) and Co-CoO (2.4 µm wide) lines has been obtained by oxygen ion implantation into a lithographically masked Au-sandwiched Co thin film. Magnetoresistance along the lines (i.e., current and applied magnetic field are parallel to the lines) reveals an effective positive giant magnetoresistance (GMR) behavior at room temperature. Conversely, anisotropic magnetoresistance and GMR contributions are distinguished at low temperature (i.e., 10 K) since the O-implanted areas become exchange coupled. This planar GMR is principally ascribed to the spatial modulation of coercivity in a spring-magnet-type configuration, which results in 180° Néel extrinsic domain walls at the Co/Co-CoO interfaces. The versatility, in terms of pattern size, morphology, and composition adjustment, of this method offers a unique route to fabricate planar systems for, among others, spintronic research and applications
Healing Effect of Controlled Anti-Electromigration on Conventional and High-Tc Superconducting Nanowires

The electromigration process has the potential capability to move atoms one by one
when properly controlled. It is therefore an appealing tool to tune the cross section
of monoatomic compounds with ultimate resolution or, in the case of polyatomic
compounds, to change the stoichiometry with the same atomic precision. As
demonstrated here, a combination of electromigration and anti-electromigration can
be used to reversibly displace atoms with a high degree of control. This enables a
fine adjustment of the superconducting properties of Al weak links, whereas in Nb
the diffusion of atoms leads to a more irreversible process. In a superconductor with
a complex unit cell (La 2−x Ce x CuO 4 ), the electromigration process acts selectively on
the oxygen atoms with no apparent modification of the structure. This allows to adjust
the doping of this compound and switch from a superconducting to an insulating
state in a nearly reversible fashion. In addition, the conditions needed to replace
feedback controlled electromigration by a simpler technique of electropulsing are
discussed. These findings have a direct practical application as a method to explore
the dependence of the characteristic parameters on the exact oxygen content and pave
the way for a reversible control of local properties of nanowires.Peer reviewe
Real-Time Observation of Iodide Ion Migration in Methylammonium Lead Halide Perovskites

Organic-inorganic metal-halide perovskites (e.g. CH3NH3PbI3-xClx) emerged as a promising opto-electronic material. However, the Shockley–Queisser Limit for the power conversion efficiency (PCE) of perovskite-based photovoltaic devices has still not been reached, which was attributed to non-radiative recombination pathways, as suggested by photoluminescence (PL) inactive (or dark) areas on perovskite films. Although these observations have been related to the presence of ions/defects, the underlying fundamental physics and detailed microscopic processes, concerning trap/defect status, ion migration, etc., still remain poorly understood. Here we utilize correlated wide-field PL microscopy and impedance spectroscopy (IS) on perovskite films to in-situ investigate both the spatial and temporal evolution of these PL inactive areas under external electrical fields. We attribute the formation of PL inactive domains to the migration and accumulation of iodine ions under external fields. Hence we are able to characterize the kinetic processes and determine the drift velocities of these ions. In addition, we show that I2 vapor directly affects the PL quenching of a perovskite film, which provides evidence that the migration/segregation of iodide ions plays an important role in the PL quenching and consequently limits the PCE of organometal halide based perovskite photovoltaic devices