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https://www.readbyqxmd.com/read/28640593/dna-condensation-induced-by-a-star-shaped-hexameric-cationic-surfactant
#1
Yaxun Fan, Hua Wang, Chengqian He, Fulin Qiao, Shu Wang, Yilin Wang
The interactions between a star-shaped hexameric cationic quaternary ammonium surfactant PAHB and calf thymus DNA and induced DNA condensation were investigated by ζ-potential, dynamic light scattering, atomic force microscopy, isothermal titration calorimetry, ethidium bromide exclusion assay, circular dichroism and cytotoxicity assay. With the addition of PAHB, long extended DNA molecules exhibit successive conformational transitions from elongated coil to partially condensed cluster-like aggregate, globules-on-a-string structure, and then to fully condensed globule until the saturation point of interaction between PAHB and DNA, which is slightly above their charge neutralization point...
June 22, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28640585/thermally-and-electrically-triggered-triple-shape-memory-behavior-of-poly-vinyl-acetate-poly-lactic-acid-due-to-graphene-induced-phase-separation
#2
Mohammad Sabzi, Masoud Babaahmadi, Mohammadreza Rahnama
This work aimed to develop a facile and broadly applicable method for fabricating a multi-stimuli responsive triple-shape memory polymer (SMP). Hence, herein the SMPs were prepared through the simple physical blending of two commercially available biopolymers, poly(lactic acid) (PLA) and poly(vinyl acetate) (PVAc), in the presence of robust and conductive graphene nanoplatelets. Interestingly, atomic force microscopy (AFM) observations and thermal analyses revealed that the presence of nanofillers led to phase separation and appearance of two well-separated transition temperatures in the blend of these two miscible polymers...
June 22, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28640580/a-bio-inspired-alginate-gum-arabic-hydrogel-with-micro-nano-scale-structures-for-controlled-drug-release-in-chronic-wound-healing
#3
Mi Li, Haichang Li, Xiangguang Li, Hua Zhu, Zihui Xu, Lianqing Liu, Jianjie Ma, Mingjun Zhang
Bio-polymeric hydrogels have drawn increasingly research interests in biomaterials due to its tunable physical and chemical properties for both creating bioactive cellular micro-environment and serving as sustainable therapeutic reagents. Inspired by a naturally occurring hydrogel secreted from the carnivorous Sundew plant for trapping insects, here we have developed a bio-inspired hydrogel to deliver mitsugumin53 (MG53), an important protein in cell membrane repair, for chronic wound healing. Both chemical compositions and micro/nano morphological properties inherent from the natural Sundew hydrogel were mimicked using sodium alginate and gum arabic with calcium ion-mediated cross-linking...
June 22, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28637351/tuning-surface-chemistry-of-polyetheretherketone-by-gold-coating-and-plasma-treatment
#4
Zdeňka Novotná, Silvie Rimpelová, Petr Juřík, Martin Veselý, Zdeňka Kolská, Tomáš Hubáček, Jakub Borovec, Václav Švorčík
Polyetheretherketone (PEEK) has good chemical and biomechanical properties that are excellent for biomedical applications. However, PEEK exhibits hydrophobic and other surface characteristics which cause limited cell adhesion. We have investigated the potential of Ar plasma treatment for the formation of a nanostructured PEEK surface in order to enhance cell adhesion. The specific aim of this study was to reveal the effect of the interface of plasma-treated and gold-coated PEEK matrices on adhesion and spreading of mouse embryonic fibroblasts...
December 2017: Nanoscale Research Letters
https://www.readbyqxmd.com/read/28637186/cpg-and-methylation-dependent-dna-binding-and-dynamics-of-the-methylcytosine-binding-domain-2-protein-at-the-single-molecule-level
#5
Hai Pan, Stephanie M Bilinovich, Parminder Kaur, Robert Riehn, Hong Wang, David C Williams
The methylcytosine-binding domain 2 (MBD2) protein recruits the nucleosome remodeling and deacetylase complex (NuRD) to methylated DNA to modify chromatin and regulate transcription. Importantly, MBD2 functions within CpG islands that contain 100s to 1000s of potential binding sites. Since NuRD physically rearranges nucleosomes, the dynamic mobility of this complex is directly related to function. In these studies, we use NMR and single-molecule atomic force microscopy and fluorescence imaging to study DNA binding dynamics of MBD2...
June 20, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28636780/nanoelectrical-and-nanoelectrochemical-imaging-of-pt-p-si-and-pt-p-si-electrodes
#6
Jingjing Jiang, Zhuangqun Huang, Chengxiang Xiang, Rakesh Poddar, Hans-Joachim Lewerenz, Kimberly M Papadantonakis, Nathan Lewis, Bruce Brunschwig
The interfacial properties of electrolessly deposited Pt nanoparticles (Pt-NP) on p-Si and p+-Si electrodes have been resolved on the nanometer scale using a combination of scanning probe methods. Atomic-force microscopy (AFM) showed highly dispersed Pt nanoparticles. Conductive AFM measurements showed that only about half of the particles exhibited measurable contact currents, with a factor of 10^3 difference in current. Local current-voltage measurements revealed a rectifying junction with a resistance of ≥ 10 MΩ at the Pt-NP/p-Si interface, while Pt-NP/p+-Si samples formed an Ohmic junction with a local resistance of ≥ 1 MΩ...
June 21, 2017: ChemSusChem
https://www.readbyqxmd.com/read/28635292/assembly-morphology-diffusivity-and-indentation-of-hydrogel-supported-lipid-bilayers
#7
Tooba Shoaib, Prathima Chandra Nalam, Yichen He, Yuting Chen, Rosa M Espinosa-Marzal
Recognizing the limitations of solid-supported lipid bilayers to reproduce the behavior of cell membranes, including bendability, transmembrane protein inclusion and virus entry, this study describes a novel biomimetic system for cell membranes with the potential to overcome these and other limitations. The developed strategy utilizes a hydrogel with tunable mechanical behavior that resembles those of living cells as the soft support for the phospholipid bilayer, while a polyelectrolyte multilayer film serves as an intermediate layer to facilitate the self-assembly of the lipid bilayer on the soft cushion...
June 21, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28633527/molecular-beam-epitaxy-of-highly-crystalline-monolayer-molybdenum-disulfide-on-hexagonal-boron-nitride
#8
Deyi Fu, Xiaoxu Zhao, Yu-Yang Zhang, Linjun Li, Hai Xu, A-Rang Jang, Seong In Yoon, Peng Song, Sock Mui Poh, Tianhua Ren, Zijing Ding, Wei Fu, Tae Joo Shin, Hyeon Suk Shin, Sokrates T Pantelides, Wu Zhou, Kian Ping Loh
Atomically thin molybdenum disulfide (MoS2), a direct-band-gap semiconductor, is promising for applications in electronics and optoelectronics but the scalable synthesis of highly-crystalline film remains challenging. Here we report the successful epitaxial growth of a continuous, uniform, highly-crystalline monolayer MoS2 film on hexagonal boron nitride (h-BN) by molecular beam epitaxy. Atomic force microscopy and electron microscopy studies reveal that MoS2 grown on h-BN primarily consists of two types of nucleation grains (0o aligned and 60o anti-aligned domains)...
June 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28630898/polymeric-lithography-editor-editing-lithographic-errors-with-nanoporous-polymeric-probes
#9
Pradeep Ramiah Rajasekaran, Chuanhong Zhou, Mallika Dasari, Kay-Obbe Voss, Christina Trautmann, Punit Kohli
A new lithographic editing system with an ability to erase and rectify errors in microscale with real-time optical feedback is demonstrated. The erasing probe is a conically shaped hydrogel (tip size, ca. 500 nm) template-synthesized from track-etched conical glass wafers. The "nanosponge" hydrogel probe "erases" patterns by hydrating and absorbing molecules into a porous hydrogel matrix via diffusion analogous to a wet sponge. The presence of an interfacial liquid water layer between the hydrogel tip and the substrate during erasing enables frictionless, uninterrupted translation of the eraser on the substrate...
June 2017: Science Advances
https://www.readbyqxmd.com/read/28630488/initial-pseudo-steady-state-asymptotic-kpz-universality-in-semiconductor-on-polymer-deposition
#10
Renan A L Almeida, Sukarno O Ferreira, Isnard Ferraz, Tiago J Oliveira
The Kardar-Parisi-Zhang (KPZ) class is a paradigmatic example of universality in nonequilibrium phenomena, but clear experimental evidences of asymptotic 2D-KPZ statistics are still very rare, and far less understanding stems from its short-time behavior. We tackle such issues by analyzing surface fluctuations of CdTe films deposited on polymeric substrates, based on a huge spatio-temporal surface sampling acquired through atomic force microscopy. A pseudo-steady state (where average surface roughness and spatial correlations stay constant in time) is observed at initial times, persisting up to deposition of ~10(4) monolayers...
June 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28630162/real-time-dynamics-of-carbon-nanotube-porins-in-supported-lipid-membranes-visualized-by-high-speed-atomic-force-microscopy
#11
Yuliang Zhang, Ramya H Tunuguntla, Pyung-On Choi, Aleksandr Noy
In-plane mobility of proteins in lipid membranes is one of the fundamental mechanisms supporting biological functionality. Here we use high-speed atomic force microscopy (HS-AFM) to show that a novel type of biomimetic channel-carbon nanotube porins (CNTPs)-is also laterally mobile in supported lipid membranes, mimicking biological protein behaviour. HS-AFM can capture real-time dynamics of CNTP motion in the supported lipid bilayer membrane, build long-term trajectories of the CNTP motion and determine the diffusion coefficients associated with this motion...
August 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28629183/an-amyloidogenic-sequence-at-the-n-terminus-of-the-androgen-receptor-impacts-polyglutamine-aggregation
#12
Emmanuel Oppong, Gunter Stier, Miriam Gaal, Rebecca Seeger, Melanie Stoeck, Marc-André Delsuc, Andrew C B Cato, Bruno Kieffer
The human androgen receptor (AR) is a ligand inducible transcription factor that harbors an amino terminal domain (AR-NTD) with a ligand-independent activation function. AR-NTD is intrinsically disordered and displays aggregation properties conferred by the presence of a poly-glutamine (polyQ) sequence. The length of the polyQ sequence as well as its adjacent sequence motifs modulate this aggregation property. AR-NTD also contains a conserved KELCKAVSVSM sequence motif that displays an intrinsic property to form amyloid fibrils under mild oxidative conditions...
June 19, 2017: Biomolecules
https://www.readbyqxmd.com/read/28629010/fabrication-of-dna-nanotubes-with-an-array-of-exterior-magnetic-nanoparticles
#13
Adele Rafati, Ali Zarrabi, Pooria Gill
Described here a methodology for arraying of magnetic nanoparticles (MNPs) on the surface of DNA nanotubes (DNTs). Positioning of magnetic nanoparticles at exterior surface of DNTs were shaped after self-assembling of oligonucleotide staples within an M13mp18 DNA scaffold via an origami process. The staples were partially labeled with biotin to be arrayed at the surface of DNTs. Gel retardation assay of the DNTs carrying magnetic nanoparticles indicated a reversely behavioral electrophoretic movement in comparison to the nanotubes have been demonstrated previously...
October 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28628994/tio2-surfaces-support-neuron-growth-during-electric-field-stimulation
#14
M Canillas, B Moreno, E Chinarro, A M Rajnicek
TiO2 is proposed here for the first time as a substrate for neural prostheses that involve electrical stimulation. Several characteristics make TiO2 an attractive material: Its electrochemical behaviour as an insulator prevents surface changes during stimulation. Hydration creates -OH groups at the surface, which aid cell adhesion by interaction with inorganic ions and macromolecules in cell membranes. Its ability to neutralize reactive oxygen and nitrogen species that trigger inflammatory processes confers biocompatibility properties in dark conditions...
October 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28628642/nanoscale-quantification-of-the-biophysical-characterization-of-combretastatin-a-4-treated-tumor-cells-using-atomic-force-microscopy
#15
Yanchun Li, Jv Chen, Yutong Liu, Weige Zhang, Wenhui He, Hanying Xu, Lianqing Liu, Enlong Ma
As an inhibitor of microtubule assembly, combretastatin A-4 (CA-4)-induced biological responses in tumor cells have been well known, but the corresponding changes in nano-biophysical properties were not investigated given the lack of an ideal tool. Using AFM technique, we investigated the alteration of nano-biophysical properties when CA-4-treated tumor cells underwent the different biological processes, including cell cycle arrest, apoptosis and autophagy. We found that CA-4-resistant cells were rougher with the presence of characteristic "ridges", indicating that the development of "ridge" structure may be a determinant of the sensitivity of cells to CA-4 compounds...
2017: PloS One
https://www.readbyqxmd.com/read/28628179/nucleated-dewetting-in-supported-ultra-thin-liquid-films-with-hydrodynamic-slip
#16
Matthias Lessel, Joshua D McGraw, Oliver Bäumchen, Karin Jacobs
This study reveals the influence of the surface energy and solid/liquid boundary condition on the breakup mechanism of dewetting ultra-thin polymer films. Using silane self-assembled monolayers, SiO2 substrates are rendered hydrophobic and provide a strong slip rather than a no-slip solid/liquid boundary condition. On undergoing these changes, the thin-film breakup morphology changes dramatically - from a spinodal mechanism to a breakup which is governed by nucleation and growth. The experiments reveal a dependence of the hole density on film thickness and temperature...
June 19, 2017: Soft Matter
https://www.readbyqxmd.com/read/28627889/measuring-spatially-resolved-collective-ionic-transport-on-lithium-battery-cathodes-using-atomic-force-microscopy
#17
Aaron Mascaro, Zi Wang, Pierre Hovington, Yoichi Miyahara, Andrea Paolella, Vincent Gariepy, Zimin Feng, Tyler Enright, Connor Aiken, Karim Zaghib, Kirk H Bevan, Peter Grutter
One of the main challenges in improving fast charging lithium-ion batteries is the development of suitable active materials for cathodes and anodes. Many materials suffer from unacceptable structural changes under high currents and/or low intrinsic conductivities. Experimental measurements are required to optimize these properties, but few techniques are able to spatially resolve ionic transport properties at small length scales. Here we demonstrate an atomic force microscope (AFM)-based technique to measure local ionic transport on LiFePO4 to correlate with the structural and compositional analysis of the same region...
June 21, 2017: Nano Letters
https://www.readbyqxmd.com/read/28627502/domain-wall-magnetoresistance-in-bifeo3-thin-films-measured-by-scanning-probe-microscopy
#18
Neus Domingo, Saeedeh Farokhipoor, Jose Santiso, Beatriz Noheda, Gustau Catalan
We measure the magnetotransport properties of individual 71º domain walls in multiferroic BiFeO3 by means of conductive - atomic force microscopy (C-AFM) in the presence of magnetic fields up to one Tesla. The results suggest anisotropic magnetoresistance at room temperature, with the sign of the magnetoresistance depending on the relative orientation between the magnetic field and the domain wall plane. A consequence of this finding is that macroscopically averaged magnetoresistance measurements for domain wall bunches are likely to underestimate the magnetoresistance of each individual domain wall...
June 19, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28627135/in-situ-electrochemistry-of-rechargeable-battery-materials-status-report-and-perspectives
#19
REVIEW
Yijun Yang, Xizheng Liu, Zhonghua Dai, Fangli Yuan, Yoshio Bando, Dmitri Golberg, Xi Wang
The development of rechargeable batteries with high performance is considered to be a feasible way to satisfy the increasing needs of electric vehicles and portable devices. It is of vital importance to design electrodes with high electrochemical performance and to understand the nature of the electrode/electrolyte interfaces during battery operation, which allows a direct observation of the complicated chemical and physical processes within the electrodes and electrolyte, and thus provides real-time information for further design and optimization of the battery performance...
June 19, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28627043/fabrication-of-millimeter-long-carbon-tubular-nanostructures-using-the-self-rolling-process-inherent-in-elastic-protein-layers
#20
Hyojin Ko, Leila F Deravi, Sung-Jin Park, Jingon Jang, Takhee Lee, Cheong Kang, Jin Seok Lee, Kevin Kit Parker, Kwanwoo Shin
Millimeter-long conducting fibers can be fabricated from carbon nanomaterials via a simple method involving the release of a prestrained protein layer. This study shows how a self-rolling process initiated by polymerization of a micropatterned layer of fibronectin (FN) results in the production of carbon nanomaterial-based microtubular fibers. The process begins with deposition of carbon nanotube (CNT) or graphene oxide (GO) particles on the FN layer. Before polymerization, particles are discrete and nonconducting, but after polymerization the carbon materials become entangled to form an interconnected conducting network clad by FN...
June 19, 2017: Advanced Materials
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