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Da Huang, Zhi Yang, Xiaolin Li, Liling Zhang, Jing Hu, Yanjie Su, Nantao Hu, Guilin Yin, Dannong He, Yafei Zhang
Graphene is an ideal candidate for gas sensing due to its excellent conductivity and large specific surface areas. However, it usually suffers from sheet stacking, which seriously debilitates its sensing performance. Herein, we demonstrate a three-dimensional conductive network based on stacked SiO2@graphene core-shell hybrid frameworks for enhanced gas sensing. SiO2 spheres are uniformly encapsulated by graphene oxide (GO) through an electrostatic self-assembly approach to form SiO2@GO core-shell hybrid frameworks, which are reduced through thermal annealing to establish three-dimensional (3D) conductive sensing networks...
October 20, 2016: Nanoscale
Jinglin Fu, Yuhe Renee Yang, Soma Dhakal, Zhao Zhao, Minghui Liu, Ting Zhang, Nils G Walter, Hao Yan
In nature, the catalytic efficiency of multienzyme complexes highly depends on their spatial organization. The positions and orientations of the composite enzymes are often precisely controlled to facilitate substrate transport between them. Self-assembled DNA nanostructures hold great promise for organizing biomolecules at the nanoscale. Here, we present detailed protocols for exploiting DNA nanostructures as assembly scaffolds that organize the spatial arrangements of multienzyme cascades with control over their relative distance, compartmentalization and substrate diffusion paths...
November 2016: Nature Protocols
Jibin Song, Peng Huang, Xiaoyuan Chen
Gold nanovesicles contain multiple nanocrystals within a polymeric coating. The strong plasmonic coupling between adjacent nanoparticles in their vesicular shell makes ultrasensitive biosensing and bioimaging possible. In our laboratory, multifunctional plasmonic vesicles are assembled from amphiphilic gold nanocrystals (such as gold nanoparticles and gold nanorods) coated with mixed hydrophilic and hydrophobic polymer brushes or amphiphilic diblock co-polymer brushes. To fulfill the different requirements of biomedical applications, different polymers that are either pH=responsive, photoactive or biodegradable can be used to form the hydrophobic brush, while the hydrophilicity is maintained by polyethylene glycol (PEG)...
November 2016: Nature Protocols
M Hrubý, S K Filippov, P Štěpánek
Self-organization in a polymer system appears when a balance is achieved between long-range repulsive and short-range attractive forces between the chemically different building blocks. Block copolymers forming supramolecular assemblies in aqueous media represent materials which are extremely useful for the construction of drug delivery systems especially for cancer applications. Such formulations suppress unwanted physicochemical properties of the encapsulated drugs, modify biodistribution of the drugs towards targeted delivery into tissue of interest and allow triggered release of the active cargo...
October 20, 2016: Physiological Research
Xianyu Song, Shuangliang Zhao, Shenwen Fang, Yongzhang Ma, Ming Duan
The dissipative particle dynamics (DPD) method is used to investigate the adsorption behavior of PEO-PPO-PEO triblock copolymers at the liquid/solid interface. The effect of molecular architecture on the self-assembled monolayer adsorption of PEO-PPO-PEO triblock copolymers on hydrophobic surfaces is elucidated by adsorption process, film properties, adsorption morphologies, respectively. The adsorption thicknesses on hydrophobic surfaces and diffusion coefficient as well as aggregation number of Pluronic copolymers in aqueous solution observed in our simulations agree well with previous experimental and numerical observations...
October 20, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Qiang Zhao, Zhen Lian, Xuedong Gao, Yun Yan, Jianbin Huang
The ability to modulate the amphiphilic aggregation reversibly with external stimuli, especially by light trigger, is of great importance. It makes great contribution to the development of applications by self-assembly. However, most previously described systems are based on specific molecular design and difficultly applied in light-inert aggregations. Here we develop a general and effective approach to control the morphology of amphiphilic aggregates by light, which is suitable for different assemblies such as micelle, vesicle and helix...
October 20, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Ana Marina Ferreira, Piergiorgio Gentile, Sotiria Toumpaniari, Gianluca Ciardelli, Mark A Birch
Bone cell interaction with extracellular matrix (ECM) microenvironment is of critical importance when engineering surface interfaces for bone regeneration. In this work layer-by-layer films of type I collagen (coll), the major constituent of bone ECM, and heparin (hep), a glycosaminoglycan, were assembled on poly(L-lactide acid) (PLLA) substrates to evaluate the impact of the biomacromolecular coating on cell activity. The surface modification of PLLA demonstrated that the hep/coll multi-layer is stable after 10 bilayers (confirmed by contact angle, infrared spectroscopy and morphological analysis)...
October 20, 2016: ACS Applied Materials & Interfaces
Dong-Gue Kang, Minwook Park, Dae-Yoon Kim, Munju Goh, Namil Kim, Kwang-Un Jeong
For the development of advanced heat transfer organic materials (HTOMs) with excellent thermal conductivities, triphenylene-based reactive discogens, 2,3,6,7,10,11-hexakis(but-3-enyloxy) triphenylene (HABET) and 4,4',4'',4''',4'''',4'''''-(triphenylene-2,3,6,7,10,11-hexaylhexakis(oxy)) hexakis(butane-1-thiol) (THBT), were synthesized as discotic liquid crystal (DLC) monomers and crosslinkers, respectively. Temperature-composition phase diagram of HABET-THBT mixtures was first established based on their thermal and microscopic analyses...
October 20, 2016: ACS Applied Materials & Interfaces
Hiroshi Yoshida, Yusuke Goto, Rena Akahori, Yasuhiko Tada, Shohei Terada, Motonori Komura, Tomokazu Iyoda
We report a novel approach to slow the translocation of single-stranded DNA (ssDNA) by employing polyethylene oxide (PEO) filled nano-cylindrical domains as transportation channels. DNA strands were demonstrated to electrophoretically translocate through PEO filled cylindrical domains with diameters of 2 and 9 nm, which were self-assembled by amphiphilic liquid crystalline block copolymers. The average translocation rate of ssDNA strands was effectively reduced to an order of 10 μs per nucleotide, which was 1-2 orders slower than that attained by utilizing conventional solid-state nanopore devices...
October 20, 2016: Nanoscale
Guang Yang, Daniel T Hallinan
Using a three-phase system, centimeter-scale monolayer gold nanoparticle (Au NP) films have been prepared that have long-range order and hydrophobic ligands. The system contains an interface between an aqueous phase containing Au NPs and an oil phase containing one of various types of amine ligands, and a water/air interface. As the Au NPs diffuse to the water/oil interface, ligand exchange takes place which temporarily traps them at the water/oil interface. The ligand-exchanged particles then spontaneously migrate to the air/water interface, where they self-assemble, forming a monolayer under certain conditions...
October 20, 2016: Scientific Reports
Meizhen Yin, Baozhong Lü, Shusen You, Pengyu Li, Chen Li, Klaus Müllen
Supramolecular self-assembly has attracted increasing attention as a breakthrough methodology in the fields of nanoscience and nanotechnology. In this study, a perylene dianhydride derivative (TP-PDA) self-assembles into well-defined nanospheres through a nucleation-growth process. The mechanisms of this process are explored by spectral ananlysis, dynamic light scattering (DLS) and scanning electron microscopy (SEM). Both in-situ DLS and in-situ SEM reveal that the sizes of aggregated nanospheres increase with time until the formation of equilibrium H-aggregates...
October 20, 2016: Chemistry: a European Journal
Hiroaki Sakamoto, Tomohiro Komatsu, Koji Yamasaki, Takenori Satomura, Shin-Ichiro Suye
OBJECTIVES: To design and construct a novel bio-anode electrode based on the oxidation of glutamic acid to produce 2-oxoglutarate, generating two electrons from NADH. RESULTS: Efficient enzyme reaction and electron transfer were observed owing to immobilization of the two enzymes using a mixed self-assembled monolayer. The ratio of the immobilized enzymes was an important factor affecting the efficiency of the system; thus, we quantified the amounts of immobilized enzyme using a quartz crystal microbalance to further evaluate the electrochemical reaction...
October 19, 2016: Biotechnology Letters
Papri Sutar, Tapas Kumar Maji
We design a flexible, amphiphilic LMWG consisting of donor and acceptor π-chromophores which self-assembles into a hydrogel and an organogel with different nano-morphologies. Different mechanisms of self-assembly evolve charge transfer (CT) emission in the hydrogel and LMWG-based emission in the organogel. Moreover, the hydrogel-nanostructure with surface exposed amide groups is explored for catalyzing Knoevenagel condensation reaction.
October 20, 2016: Chemical Communications: Chem Comm
Carolin de Groot, Christel C Müller-Goymann
Saponins are used in medicine due to their pharmacological and immunological effects. To better understand interactions of saponins with model membranes and natural membranes of, for example, erythrocytes, Langmuir film balance experiments are well established. For most saponins, a strong interaction with cholesterol was demonstrated in dependence of both the aglycone part and the sugar moieties and is suggested to be correlated with a strong hemolytic activity, high toxicity, and high surface activity, as was demonstrated for the steroid saponin digitonin...
October 19, 2016: Planta Medica
Nobuo Kimizuka, Nobuhiro Yanai, Masa-Aki Morikawa
Self-assembly of functional molecules into ordered molecular assemblies and fulfillment of potentials unique to their nano-to-mesoscopic structures have been one of the central challenges in chemistry. This Feature Article provides an overview of recent progress in the field of molecular self-assembly with the focus on the triplet-triplet annihilation-based photon upconversion (TTA-UC) and supramolecular storage of photon energy. Based on the integration of molecular self-assembly and photon energy harvesting, triplet energy migration-based TTA-UC has been achieved in varied molecular systems...
October 19, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Xunzhi Li, Wenchuan Ma, Alexander A Shestopalov
This study describes formation of functional organic monolayers on hard and soft interfaces via a vapor-phase carbene insertion into Si-H and C-H bonds. We demonstrate that functional diazirine molecules can be used to form mono-molecular coatings on silicon, silicon nitride and urethane-acrylate polymers under mild vacuum conditions and exposure to UV light. We investigate the molecular coverage and the long-term stability of the resulting monolayers in air, isopropanol and water. Our results suggest that vapor-phase carbenylation can be used as a complementary technology to the traditional self-assembly, permitting functionalization of various passivated substrates with stable and functional molecular coatings under mild and scalable conditions...
October 19, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Fengyang Xu, Jie Liu, Jian Tian, Lingfeng Gao, Xiaju Cheng, Yue Pan, Ziling Sun, Xinming Li
In this work, we reported the generation of a novel supramolecular hydrogelator from a peptide derivative which consisted of a structural motif (e.g., Fc-FF) for supramolecular self-assembly and a functional moiety (e.g., RGD) for integrin binding. Following self-assembly in water at neutral pH, this molecule firstly tended to form metastable spherical aggregates, which subsequently underwent a morphological transformation to form high-aspect-ratio nanostructures over 2 h when aged at room temperature. More importantly, because of the presence of nanoscale RGD clusters on the surface of nanostructures, the self-assembled nanomaterials (e...
October 19, 2016: ACS Applied Materials & Interfaces
Leonora Velleman, Debabrata Sikdar, Vladimir A Turek, Anthony R Kucernak, Steve J Roser, Alexei A Kornyshev, Joshua B Edel
Understanding the structure and assembly of nanoparticles at liquid|liquid interfaces is paramount to their integration into devices for sensing, catalysis, electronics and optics. However, many difficulties arise when attempting to resolve the structure of such interfacial assemblies. In this article we use a combination of X-ray diffraction and optical reflectance to determine the structural arrangement and plasmon coupling between 12.8 nm diameter gold nanoparticles assembled at a water|1,2-dichloroethane interface...
October 19, 2016: Nanoscale
Junyi Che, Anqi Tao, Shun Chen, Xiaoming Li, Yi Zhao, Weien Yuan
Small interfering RNA (siRNA) has increased the hope for highly-efficient treatment of gene-related diseases. However, the stable and efficient delivery of therapeutic nucleic acids is a prerequisite for the successful clinical translation of RNA interfering therapy. To achieve this, we condensed the low molecular weight polyethyleneimine (PEI, Mw < 2000) with 2,6-pyridinedicarboxaldehyde (PDA) to synthesize a biologically responsive and degradable cationic polymer (abbreviated to PDAPEI) which was utilized as a gene vector for the delivery of a VEGF-A shRNA expression plasmid DNA (pDNA)...
October 19, 2016: Scientific Reports
Mingwei Wan, Xiaoxu Li, Lianghui Gao, Weihai Fang
The self-assembly of phospholipid-coated gold nanorods (GNRs) was investigated by coarse-grained molecular dynamics simulations. We predict that in addition to the formation of deformed vesicles encapsulating GNRs with diverse orientations, the lipid-coated GNRs can form a semi-ring attached to an excess vesicle phase, a branch with excess vesicle phase, a ring phase, a branch phase, a stack phase, and a vortex phase. The morphologies of the lipid-GNR complexes depend on the lipid/GNR molar ratio and the interaction strength between the nanorod surface and the lipid head groups...
October 19, 2016: Nanotechnology
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