pinecone/core-2020-05-10-deduplication huggingface dataset:
Self-assembly of hydrophilic homopolymers: a matter of RAFT end groups

This is the peer reviewed version of the following article: DU, J. ... et al., 2011. Self-assembly of hydrophilic homopolymers: a matter of RAFT end groups. Small, 7 (14), pp.2070-2080, which has been published in final form at: http://dx.doi.org/10.1002/smll.201100382. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.Unusual self-assembly behavior is observed for a range of hydrophilic homopolymers. This self-assembly behavior is contrary to the expected behavior of such hydrophilic polymers and instead mimics more commonly reported amphiphilic block copolymers. It is proposed that the unique combination of hydrophobic end groups at both the α and Ω chain end accounts for this unusual self-assembly behavior. Complex internal polymer micelles are spontaneously formed when hydrophilic homopolymer polyelectrolytes and neutral polymers (with a weight fraction of the hydrophobic end groups <10 wt%) are directly dissolved in water. The homopolymers, poly[2-(diethylamino)ethyl methacrylate], poly(N-isopropylacrylamide), and poly(ethoxyethylacrylate) are synthesized by reversible addition-fragmentation chain-transfer (RAFT) polymerization using S′-1-dodecyl-(S′)-(α,α′- dimethyl-α″-acetic acid) trithiocarbonate (DDMAT) and its derivatives as chain transfer agents (CTAs). A range of polyelectrolyte homopolymers with different terminal groups are designed and synthesized, which under acidic aqueous solution direct the self-assembly to form well-defined nanostructures. This assembly behavior was also observed for neutral polymers, and it was determined that the structure of the hydrophobic end groups (and thus choice of RAFT CTA) are very important in facilitating this unusual self-assembly behavior of hydrophilic homopolymers. It is proposed that the functionality of commonly used CTAs such as DDMAT, can affect the solution association of the resultant homopolymers and can in fact afford ABA′ type polymers, which can undergo self-assembly to form higher-order nanostructures. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Quantifying the nanomachinery of the nanoparticle-biomolecule interface

A study is presented of the nanomechanical phenomena experienced by nanoparticle-conjugated biomolecules. A thermodynamic framework is developed to describe the binding of thrombin-binding aptamer (TBA) to thrombin when the TBA is conjugated to nanorods. Binding results in nanorod aggregation (viz. directed self-assembly), which is detectable by absorption spectroscopy. The analysis introduces the energy of aggregation, separating it into TBA–thrombin recognition and surface-work contributions. Consequently, it is demonstrated that self-assembly is driven by the interplay of surface work and thrombin-TBA recognition. It is shown that the work at the surface is about −10 kJ mol−1 [mol superscript -1] and results from the accumulation of in-plane molecular forces of pN magnitude and with a lifetime of <1 s, which arises from TBA nanoscale rearrangements fuelled by thrombin-directed nanorod aggregation. The obtained surface work can map aggregation regimes as a function of different nanoparticle surface conditions. Also, the thermodynamic treatment can be used to obtain quantitative information on surface effects impacting biomolecules on nanoparticle surfaces.MIT-IQS Exchange Progra
Plasmonic nickel nanoantennas

7 páginas, 6 figuras.-- El pdf del artículo es la versión post-print.-- et al.The fundamental optical properties of pure nickel nanostructures are studied by far-field extinction spectroscopy and optical near-field microscopy, providing direct experimental evidence of the existence of particle plasmon resonances predicted by theory. Experimental and calculated near-field maps allow for unambiguous identification of dipolar plasmon modes. By comparing calculated near-field and far-field spectra, dramatic shifts are found between the near-field and far-field plasmon resonances, which are much stronger than in gold nanoantennas. Based on a simple damped harmonic oscillator model to describe plasmonic resonances, it is possible to explain these shifts as due to plasmon damping.Supported by the European FP7 project ‘Nanoantenna’ (FP7-HEALTH-F5-2009-241818-NANOANTENNA) and the National Project MAT2009 –08398 from the Spanish Ministerio de Ciencia\ud
e Innovacion. J.A. acknowledges fi nancial help by the Department of Industry of the Basque Government through the ETORTEK program NANOPHOT. P.V. acknowledges funding from the Basque Government under Programs No. PI2009–17 as well as the Spanish Ministry of Science and Education under Project No. MAT2009–07980. Z. P. acknowledges support from Swedish Foundation for\ud
Strategic Research through RMA08–0109 “Functional Electromagnetic Metamaterials” program. J. N. acknowledges funding from the Generalitat de Catalunya and the Spanish Ministry of Science\ud
and Education through No. 2009-SGR-1292 and No. MAT2010–20616-C02 projects. A.D. acknowledges support from the Swedish Research Council.Peer reviewe
Layer-by-layer assembly of chitosan and recombinant biopolymers into biomimetic coatings with multiple stimuli-responsive properties

In this work, biomimetic smart thin coatings using chitosan and a recombinant elastin-like recombinamer (ELR) containing the cell attachment sequence arginine–glycine–(aspartic acid) (RGD) are fabricated through a layer-by-layer approach. The synthetic polymer is characterized for its molecular mass and composition using mass spectroscopy and peptide sequencing. The adsorption of each polymeric layer is followed in situ at room temperature and pH 5.5 using a quartz-crystal microbalance with dissipation monitoring, showing that both polymers can be successfully combined to conceive nanostructured, multilayered coatings. The smart properties of the coatings are tested for their wettability by contact angle (CA) measurements as a function of external stimuli, namely temperature, pH, and ionic strength. Wettability transitions are observed from a moderate hydrophobic surface (CAs approximately from 62° to 71°) to an extremely wettable one (CA considered as 0°) as the temperature, pH, and ionic strength are raised above 50 °C, 11, and 1.25 m, respectively. Atomic force microscopy is performed at pH 7.4 and pH 11 to assess the coating topography. In the latter, the results reveal the formation of large and compact structures upon the aggregation of ELRs at the surface, which increase water affinity. Cell adhesion tests are conducted using a SaOs-2 cell line. Enhanced cell adhesion is observed in the coatings, as compared to a coating with a chitosan-ending film and a scrambled arginine–(aspartic acid)–glycine (RDG) biopolymer. The results suggest that such films could be used in the future as smart biomimetic coatings of biomaterials for different biomedical applications, including those in tissue engineering or in controlled delivery systems.CIBER-BBN (project CB06-01-0003)European regional development fund (ERDF)Junta de Castilla y LeonNetwork Center of Regenerative Medicine and Cellular Therapy of Castilla and LeónEUJCyL - VA034A09, VA030A08Fundação para a Ciência e Tecnologia (FCT) - SFRH/BD/61126/2009, SFRH/BD/61390/2009MICINN - MAT 2007-66275-C02-01, MAT 2007-61604, MAT 2009-14195-C03-03, PSE-300100-2006-
Physical Aspects of Cell Culture Substrates: Topography, Roughness, and Elasticity

The cellular environment impacts a myriad of cellular functions by providing signals that can modulate cell phenotype and function. Physical cues such as topography, roughness, gradients, and elasticity are of particular importance. Thus, synthetic substrates can be potentially useful tools for exploring the influence of the aforementioned physical properties on cellular function. Many micro‐ and nanofabrication processes have been employed to control substrate characteristics in both 2D and 3D environments. This review highlights strategies for modulating the physical properties of surfaces, the influence of these changes on cell responses, and the promise and limitations of these surfaces in in‐vitro settings. While both hard and soft materials are discussed, emphasis is placed on soft substrates. Moreover, methods for creating synthetic substrates for cell studies, substrate properties, and impact of substrate properties on cell behavior are the main focus of this review.     The cellular environment  plays a significant role in cell phenotype and function. As such, physical properties of cell culture substrates including topography, roughness, and elasticity may be utilized to investigate the influence of these physical cues on the cellular response. In this review, strategies for modulating the physical properties of surfaces, the influence of these changes on cell responses, and the promise and limitations of these surfaces in in‐vitro settings are highlighted, with a particular emphasis on elastic substrates
Probing the electromagnetic field distribution within a metallic nanodisk

A Co nanolayer is used as a local probe to evaluate the vertical inhomogeneous distribution of the electromagnetic (EM) field within a resonant metallic nanodisk. Taking advantage of the direct relation between the magneto-optical activity and the electromagnetic field intensity in the Co layer, it is shown that the nonuniform EM distribution within the nanodisk under plasmon resonant conditions has maximum values close to the upper and lower flat faces, and a minimum value in the middle. Magnetoplasmonic Au/Co/Au nanodisks are fabricated by hole mask colloidal lithography, thermal evaporation, and sputtering with different positions of the Co layer in the vertical direction. The Magneto-optical activity as a function of the Co layer position gives a direct picture of the internal electromagnetic field distribution within the nanodisk when the localized surface plasmon resonance is excited. Theoretical calculations confirm these experimental findings. © 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim.The authors acknowledge funding support from the EU (NMP3- SL-2008-214107-Nanomagma), the Spanish MICINN (“FUNCOAT” CONSOLIDER INGENIO 2010 CSD2008-00023 and MAGPLAS MAT2008-06765-C02-01/NAN), the Comunidad de Madrid (“NANOBIOMAGNET”, S2009/MAT–1726 and “MICROSERES-CM”, S2009/TIC–1476) and CSIC (JAE fellowship for E. Ferreiro-Vila and JAE Doc fellowship for D. Meneses-Rodríguez).Peer Reviewe
Hydrogel Nanoparticles with Covalently Linked Coomassie Blue for Brain Tumor Delineation Visible to the Surgeon

Delineation of tumor margins is a critical and challenging objective during brain cancer surgery. A tumor‐targeting deep‐blue nanoparticle‐based visible contrast agent is described, which, for the first time, offers in vivo tumor‐specific visible color staining. This technology thus enables color‐guided tumor resection in real time, with no need for extra equipment or special lighting conditions. The visual contrast agent consists of polyacrylamide nanoparticles covalently linked to Coomassie Blue molecules (for nonleachable blue color contrast), which are surface‐conjugated with polyethylene glycol and F3 peptides for efficient in vivo circulation and tumor targeting, respectively.     Hydrogel nanoparticles containing a high concentration  of visible dye by covalent linkage, with PEGylated surface and conjugated tumor targeting moiety, enable visual delineation of brain tumors in vitro and in vivo. This technology enables color‐guided tumor resection in real time, with no need for extra equipment or special lighting conditions
Graphene Sheets Stabilized on Genetically Engineered M13 Viral Templates as Conducting Frameworks for Hybrid Energy-Storage Materials

Utilization of the material-specific peptide–substrate interactions of M13 virus broadens colloidal stability window of graphene. The homogeneous distribution of graphene is maintained in weak acids and increased ionic strengths by complexing with virus. This graphene/virus conducting template is utilized in the synthesis of energy-storage materials to increase the conductivity of the composite electrode. Successful formation of the hybrid biological template is demonstrated by the mineralization of bismuth oxyfluoride as a cathode material for lithium-ion batteries, with increased loading and improved electronic conductivity.National Institute for International Education (Korea) (Korean Government Scholarship Program)United States. Army Research Office (Institute for Collaborative Biotechnologies (ICB))National Institutes of Health (U.S.) (Materials Research Science and Engineering Centers program
DNA-Length-Dependent Fluorescence Signaling on Graphene Oxide Surface

This is the peer reviewed version of the following article: Huang, P.-J. J., & Liu, J. (2012). DNA-Length-Dependent Fluorescence Signaling on Graphene Oxide Surface. Small, 8(7), 977–983, which has been published in final form at https://doi.org/10.1002/smll.201102156. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.Fluorescence energy transfer to graphene oxide is studied using covalently linked DNA probes ranging from 4 to 70 base pairs. The characteristic distance and mechanism of energy transfer are reported.University of Waterloo ||
Canadian Foundation for Innovation ||
Natural Sciences and Engineering Research Council ||
Ontario Ministry of Research and Innovation |
Liquid Crystal Order in Colloidal Suspensions of Spheroidal Particles by Direct Current Electric Field Assembly

D C electric fields are used to produce colloidal assemblies with orientational and layered positional order from a dilute suspension of spheroidal particles. These 3D assemblies, which can be visualized in situ by confocal microscopy, are achieved in short time spans ( t  < 1 h) by the application of a constant voltage across the capacitor‐like device. This method yields denser and more ordered assemblies than had been previously reported with other assembly methods. Structures with a high degree of orientational order as well as layered positional order normal to the electrode surface are observed. These colloidal structures are explained as a consequence of electrophoretic deposition and field‐assisted assembly. The interplay between the deposition rate and the rotational Brownian motion is found to be critical for the optimal ordering, which occurs when these rates, as quantified by the Peclet number, are of order one. The results suggest that the mechanism leading to ordering is equilibrium self‐assembly but with kinetics dramatically accelerated by the application of the DC electric field. Finally, the crystalline symmetry of the densest structure formed is determined and compared with previously studied spheroidal assemblies.     Rapid assembly of anisotropic colloidal particles  is essential to create complex, uniform, and scalable crystal structures for applications. In this study, DC electric fields are used to accelerate the self‐assembly process of spheroidal particles. The image shows confocal microscopy images and renderings from image processing of the field‐induced 3D ordering. The assembly is shown to have high‐quality orientational order and previously unobserved periodic and dense layered ordering
'Fairy Chimney'-Shaped Tandem Metamaterials as Double Resonance SERS Substrates

Cataloged from PDF version of article.A highly tunable design for obtaining double resonance substrates to be used in surface-enhanced Raman spectroscopy is proposed. Tandem truncated nanocones composed of Au-SiO2-Au layers are designed, simulated and fabricated to obtain resonances at laser excitation and Stokes frequencies. Surface-enhanced Raman scattering experiments are conducted to compare the enhancements obtained from double resonance substrates to those obtained from single resonance gold truncated nanocones. The best enhancement factor obtained using the new design is 3.86 x 107. The resultant tandem structures are named after Fairy Chimneys rock formation in Cappadocia, Turkey
Interactions of Engineered Nanoparticles with\ud
Organs Protected by Internal Biological Barriers

Engineered nanomaterials may exert adverse effects on human health which, in turn, may be linked\ud
to their propensity to cross biological barriers in the body. Here, we will discuss available evidence\ud
based on in vivo studies for interactions of commercially relevant nanoparticles with critical internal\ud
barriers. The internal barriers at focus of this review are the blood-brain barrier (BBB), protecting\ud
the brain, the blood-testis barrier (BTB), protecting the male germ line, and the placenta, protecting\ud
the developing fetus. The route of exposure (pulmonary, gastrointestinal, intravenous,\ud
intraperitoneal, dermal), and the portal of entry of nanoparticles into the body, is of critical\ud
importance. Different physico-chemical properties, not only size, may determine the ability of\ud
nanoparticles to breach biological barriers; the situation is further compounded by the formation of\ud
a so-called corona of biomolecules on the surface of nanoparticles, the composition of which may\ud
vary depending on the route of exposure and the “history” of the nanoparticles as they translocate\ud
from one biological compartment to another. The relevance of nanoparticle interactions with\ud
internal biological barriers for their impact on the organs protected by these barriers is discussed
Facile Synthesis of Luminescent AgInS 2 –ZnS Solid
Solution Nanorods

Cataloged from PDF version of article.Highly luminescent semiconducting AgInS2–ZnS solid solution nanorods are successfully prepared by a facile one-pot solvothermal method. The resulting solid solution nanorods with length of 32 ± 5 nm are formed by fast growth of the AgInS2-rich solid solution head, followed by slow growth of the ZnS-rich solid solution tail. Photoluminescence studies on the solid solution nanorods reveal strong photoluminescence with peak emission wavelengths tunable from 650 to 700 nm
Oxidation Level-Dependent Zwitterionic Liposome Adsorption and Rupture by Graphene-based Materials and Light-Induced Content Release

This is the peer reviewed version of the following article: Ip, A. C.-F., Liu, B., Huang, P.-J. J., & Liu, J. (2013). Oxidation Level-Dependent Zwitterionic Liposome Adsorption and Rupture by Graphene-based Materials and Light-Induced Content Release. Small, 9(7), 1030–1035. https://doi.org/10.1002/smll.201202710, which has been published in final form at http://dx.doi.org/10.1002/smll.201202710. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.Liposomes may be stably adsorbed or ruptured on graphene-based materials, depending on the oxidation state of graphene. IR-induced liposome leakage is achieved, since graphene oxide does not induce liposome leakage spontaneously.University of Waterloo ||
Canadian Foundation for Innovation ||
Natural Sciences and Engineering Research Council ||
Ontario Ministry of Research and Innovation |
Decoupled Control of Carbon Nanotube Forest Density and Diameter by Continuous‐Feed Convective Assembly of Catalyst Particles

The widespread potential application of vertically aligned carbon nanotube (CNT) forests have stimulated recent work on large‐area chemical vapor deposition growth methods, but improved control of the catalyst particles is needed to overcome limitations to the monodispersity and packing density of the CNTs. In particular, traditional thin‐film deposition methods are not ideal due to their vacuum requirements, and due to limitations in particle uniformity and density imposed by the thin‐film dewetting process. Here, a continuous‐feed convective self‐assembly process for manufacturing uniform mono‐ and multi‐layers of catalyst particles for CNT growth is presented. Particles are deposited from a solution of commercially available iron oxide nanoparticles, by pinning the meniscus between a blade edge and the substrate. The substrate is translated at constant velocity under the blade so the meniscus and contact angle remain fixed as the particles are deposited on the substrate. Based on design of the particle solution and tuning of the assembly parameters, a priori control of CNT diameter and packing density is demonstrated. Quantitative relationships are established between the catalyst size and density, and the CNT morphology and density. The roll‐to‐roll compatibility of this method, along with initial results achieved on copper foils, suggest promise for scale‐up of CNT forest manufacturing at commercially relevant throughput.     Continuous‐feed evaporative self‐assembly  is used to create nanoparticle arrays for carbon nanotube (CNT) film growth. This versatile method enables specification of the CNT film morphology, and wide‐range tuning of the diameter and density of CNT forests. The present results exceed the performance limits of thin‐film catalyst dewetting, and the process is compatible with roll‐to‐roll manufacturing on flexible substrates
Cross-Linked g-C3N4/rGO Nanocomposites with  Tunable Band Structure and Enhanced Visible Light  Photocatalytic Activity

Cross-linked rather than non-covalently bonded graphitic carbon nitride (g-C 3 N 4 )/ reduced graphene oxide (rGO) nanocomposites with tunable band structures have been successfully fabricated by thermal treatment of a mixture of cyanamide and graphene oxide with different weight ratios. The experimental results indicate that compared to pure g-C 3 N 4 , the fabricated CN/rGO nanocomposites show narrowed bandgaps with an increased in the rGO ratio. Furthermore, the band structure of the CN/rGO nanocomposites can be readily tuned by simply controlling the weight ratio of the rGO. It is found that an appropriate rGO ratio in nanocomposite leads to a noticeable positively shifted valence band edge potential, meaning an increased oxidation power. The tunable band structure of the CN/rGO nanocomposites can be ascribed to the formation of C - O - C covalent bonding between the rGO and g-C 3 N 4 layers, which is experimentally confi rmed by Fourier transform infrared (FT-IR) and X-ray photoelectron (XPS) data. The resulting nanocomposites are evaluated as photocatalysts by photocatalytic degradation of rhodamine B (RhB) and 4-nitrophenol under visible light irradiation ( ? > 400 nm). The results demonstrate that the photocatalytic activities of the CN/rGO nanocomposites are strongly influenced by rGO ratio. With a rGO ratio of 2.5%, the CN/rGO-2.5% nanocomposite exhibits the highest photocatalytic effi ciency, which is almost 3.0 and 2.7 times that of pure g-C 3 N 4 toward photocatalytic degradation of RhB and 4-nitrophenol, respectively. This improved photocatalytic activity could be attributed to the improved visible light utilization, oxidation power, and electron transport property, due to the signifi cantly narrowed bandgap, positively shifted valence band-edge potential, and enhanced electronic conductivity.Griffith Sciences, Griffith School of EnvironmentFull Tex