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nano catalysis

Maria Wadsäter, Justas Barauskas, Fredrik Tiberg, Tommy Nylander
The effects of different lipolytic enzymes on the structure of lipid liquid crystalline nano-particles (LCNP) have been investigated by cryogenic transmission electron microscopy (cryo-TEM) and synchrotron small angle X-ray diffraction (SAXD). Here we used highly structured cubic micellar (Fd3m) nanoparticles of 50/50 (wt%/wt%) soy phosphatidyl choline (SPC)/glycerol dioleate (GDO) as substrate. Two types of lipolytic enzymes were used, phospholipase A2 (PLA2) that catalysis degradation of the phospholipid component, SPC, and porcine pancreatic triacylglycerol lipase (TGL) that facilitate the hydrolysis of the diglyceride, GDO...
November 10, 2017: Chemistry and Physics of Lipids
Weiyi Zhang, Qiang Zhao, Jiayin Yuan
The past decade has witnessed rapid advances in porous polyelectrolytes and there is tremendous ongoing interest in their synthesis and applications in environment, energy, biomedicine and catalysis. The porous polyelectrolytes research is motivated by the synergy of, apart from the flexible choice of functional organic groups and processing technologies, the charge and pores spanning length scales from individual polyelectrolyte backbones to their nano/micro superstructures. This review surveys recent progresses on porous polyelectrolytes including membranes, particles, scaffolds, high surface area powders/resins, and their derivatives...
November 9, 2017: Angewandte Chemie
Silvia A Blank-Shim, Sebastian P Schwaminger, Monika Borkowska-Panek, Priya Anand, Peyman Yamin, Paula Fraga-García, Karin Fink, Wolfgang Wenzel, Sonja Berensmeier
Magnetic nanoparticles (MNP) are intensively investigated for applications in nanomedicine, catalysis and biotechnology, where their interaction with peptides and proteins plays an important role. However, the characterisation of the interaction of individual amino acids with MNP remains challenging. Here, we classify the affinity of 20 amino acid homo-hexamers to unmodified iron oxide nanoparticles using peptide arrays in a variety of conditions as a basis to identify and rationally design selectively binding peptides...
October 25, 2017: Scientific Reports
Badri Narayanan, Henry Chan, Alper Kinaci, Fatih G Sen, Stephen K Gray, Maria K Y Chan, Subramanian K R S Sankaranarayanan
A fundamental understanding of the inter-relationships between structure, morphology, atomic scale dynamics, chemistry, and physical properties of mixed metallic-covalent systems is essential to design novel functional materials for applications in flexible nano-electronics, energy storage and catalysis. To achieve such knowledge, it is imperative to develop robust and computationally efficient atomistic models that describe atomic interactions accurately within a single framework. Here, we present a unified Tersoff-Brenner type bond order potential (BOP) for a Co-C system, trained against lattice parameters, cohesive energies, equation of state, and elastic constants of different crystalline phases of cobalt as well as orthorhombic Co2C derived from density functional theory (DFT) calculations...
October 18, 2017: Nanoscale
Fatma Vatansever, Michael R Hamblin
New methods are needed for covalent functionalization of nanoparticles-surface with organic polymer coronas to generate polymeric nanocomposite in a controlled manner. Here we report the use of a surface-initiated polymerization approach, mediated by titanium (IV) catalysis, to grow poly(n-hexylisocyanate) chains from silica surface. Two pathways were used to generate the interfacing in these nano-hybrids. In the first one, the nanoparticles was "seeded" with SiCl4, followed by reaction with 1,6-hexanediol to form hydroxyl groups attached directly to the surface via O-Si-O bonding...
February 2017: Macromolecular Research
Jian Zhu, Shan Pang, Thomas Dittrich, Yuying Gao, Wei Nie, Junyan Cui, Ruotian Chen, Hongyu An, Fengtao Fan, Can Li
The cocatalysts or dual cocatalysts of photocatalysts are indispensable for high efficiency in artificial photosynthesis for solar fuel production. However, the reaction activity increased by cocatalysts cannot be directly ascribed to the accelerated catalytic kinetics, since photogenerated charges are involved in the elementary steps of photocatalytic reactions. To date, diverging views about cocatalysts show that their exact role for photocatalysis is not well understood yet. Herein, we image directly the local separation of photogenerated charge carriers across single crystals of the BiVO4 photocatalyst which loaded locally with nanoparticles of a MnOx single cocatalyst or with nanoparticles of a spatially separated MnOx and Pt dual cocatalyst...
October 5, 2017: Nano Letters
Feng Ji, Dong Men, Dianbing Wang, Xian-En Zhang
There are various nanostructures in biological system. They are made of biological molecules via self-assembly with well-organized architectures and specific functions. These nanostructures can be grouped into lines, layers and cages, corresponding to one-, two- and three-dimensional structures, respectively. The bionanostructures can serve as the models or templates for biosynthesis of biodevices with desired functions by rational design. Proof-of-concept studies have shown their attractive performance in practical applications, e...
March 25, 2017: Sheng Wu Gong Cheng Xue Bao, Chinese Journal of Biotechnology
Natalia Martín Sabanés, Katrin F Domke
Electrochemistry is re-gaining attention among scientists because the complex interplay between electronic and chemical interfacial processes lies at the bottom of a broad range of important research disciplines like alternative energy conversion or green catalysis and synthesis. While rapid progress has been made in recent years regarding novel technological applications, the community increasingly recognizes that the understanding of the molecular processes that govern macroscopic device properties is still rather limited - which hinders a systematic and more complete exploration of novel material and functionality space...
August 2017: ChemElectroChem
Fabian Itel, Philipp S Schattling, Yan Zhang, Brigitte Städler
Cell mimicry is a nature inspired concept that aims to substitute for missing or lost (sub)cellular function. This review focuses on the latest advancements in the use of enzymes in cell mimicry for encapsulated catalysis and artificial motility in synthetic bottom-up assemblies with emphasis on the biological response in cell culture or more rarely in animal models. Entities across the length scale from nano-sized enzyme mimics, sub-micron sized artificial organelles and self-propelled particles (swimmers) to micron-sized artificial cells are discussed...
September 12, 2017: Advanced Drug Delivery Reviews
A Poma, A Forni, C Baldoli, P R Mussini, A Bossi
Square planar platinum complexes are an important class of compounds used in (nano)technology, optoelectronics, medicinal chemistry and catalysis. The major research interests in cyclometalated Pt(ii) complexes focus on the selective modulation of their electronic properties and the control of the (cis/trans) geometry. For the first time, we unveil and demonstrate that cis-trans isomers of Pt(ii) complexes can be obtained in a derivative carrying the 1-phenyl-pirazolate (Hppz) and 2-hydroxy-1-naphtyl-(N-phenyl)imine ligands...
September 26, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Sofia Marchesini, Catriona M McGilvery, Josh Bailey, Camille Petit
Production of biocompatible and stable porous materials, e.g., boron nitride, exhibiting tunable and enhanced porosity is a prerequisite if they are to be employed to address challenges such as drug delivery, molecular separations, or catalysis. However, there is currently very limited understanding of the formation mechanisms of porous boron nitride and the parameters controlling its porosity, which ultimately prevents exploiting the material's full potential. Herein, we produce boron nitride with high and tunable surface area and micro/mesoporosity via a facile template-free method using multiple readily available N-containing precursors with different thermal decomposition patterns...
October 24, 2017: ACS Nano
Martin Spitzbarth, Andreas Scherer, Andreas Schachtschneider, Peter Imming, Sebastian Polarz, Malte Drescher
Diffusion in porous materials is under ongoing active investigation due to its major role in practical applications such as catalysis and chromatography. The complexity of these systems limits the use of the Einstein-Stokes diffusion theory, and it must be distinguished between the microscopic scale of diffusion at a molecular level, which is sensitive to the local surroundings of a diffusing molecule, and the macroscopic scale which takes into account diffusion spanning multiple pores, grain boundaries and inhomogeneity within the material...
October 2017: Journal of Magnetic Resonance
Julien Ramade, Cyril Langlois, Michel Pellarin, Laurent Piccolo, Marie-Ange Lebeault, Thierry Epicier, Mimoun Aouine, Emmanuel Cottancin
Multimetallic nano-alloys display a structure and consequently physicochemical properties evolving in a reactive environment. Following and understanding this evolution is therefore crucial for future applications in gas sensing and heterogeneous catalysis. In view hereof, the structural evolution of oxidized Ag25In75 bimetallic nanoparticles under varying H2 partial pressures (PH2) and substrate temperatures (Ts) has been investigated in real-time through environmental transmission microscopy (E-TEM) while maintaining the atomic resolution...
September 21, 2017: Nanoscale
Hua Wang, Liefeng Liang, Xinjian Cheng, Yanmei Luo, Sheng Sun
Porous ZnS and ZnO nano-crystal films were fabricated via a three-step procedure. First, Zn(CH3 COO)2 /Silk Fibroin nanofiber mats were prepared by coaxial electrospinning. Second, Zn(CH3 COO)2 /Silk Fibroin mats were immersed in NaS solution to react with S(2-) to obtain ZnS/Silk Fibroin nanofiber mats. Finally, ZnO porous films were prepared by calcination of ZnS/Silk Fibroin composite mat at 600°C in air atmosphere. When ZnS/Silk Fibroin mats were calcinated in nitrogen, ZnS/Carbon composite mats were obtained accordingly...
August 31, 2017: Photochemistry and Photobiology
Hans-Joachim Freund, Wolf-Dieter Schneider, Markus Heyde
In chemistry and physics the electronic charge on a species or material is one important determinant of its properties. In the present review the essential requirements for a model catalyst system suitable to study charge control are discussed. The ideal model catalyst for this purpose consists of a material system, which comprises a single crystal metal support, covered by an epitaxially grown ultrathin oxide film, and flat, two-dimensional nano-particles residing on this film. Several examples from the published literature are selected and presented, which illustrate various aspects of electron transport from the support to the nanoparticle and vice versa...
August 31, 2017: Chemistry: a European Journal
Christoph Edlinger, Tomaz Einfalt, Mariana Spulber, Anja Car, Wolfgang Meier, Cornelia G Palivan
We describe an innovative strategy to generate catalytic compartments with triggered functionality at the nanoscale level by combining pH-reversible biovalves and enzyme-loaded synthetic compartments. The biovalve has been engineered by the attachment of stimuli-responsive peptides to a genetically modified channel porin, enabling a reversible change of the molecular flow through the pores of the porin in response to a pH change in the local environment. The biovalve functionality triggers the reaction inside the cavity of the enzyme-loaded compartments by switching the in situ activity of the enzymes on/off based on a reversible change of the permeability of the membrane, which blocks or allows the passage of substrates and products...
September 13, 2017: Nano Letters
T Jane Stockmann, Léo Angelé, Vitor Brasiliense, Catherine Combellas, Frédéric Kanoufi
Single nanoparticle (NP) electrochemistry detection at a micro liquid|liquid interface (LLI) is exploited using the catalyzed oxygen reduction reaction (ORR). In this way, current spikes reminiscent of nanoimpacts were recorded, which corresponded to electrocatalytic enhancement of the ORR by Pt NPs. The nature of the LLI allows exploration of new phenomena in single NP electrochemistry. The recorded impacts result from a bipolar reaction occurring at the Pt NP straddling the LLI. O2 reduction takes place in the aqueous phase, while ferrocene hydride (Fc-H(+) ; a complex generated upon facilitated interfacial proton transfer by Fc) is oxidized in the organic phase...
October 16, 2017: Angewandte Chemie
Zachary S Fishman, Yulian He, Ke R Yang, Amanda W Lounsbury, Junqing Zhu, Thanh Minh Tran, Julie B Zimmerman, Victor S Batista, Lisa D Pfefferle
Understanding how nano-dimensionality impacts iron oxide based catalysis is central to a wide range of applications. Here, we focus on hematite nanosheets, nanowires and nanoparticles as applied to catalyze the reverse water gas shift (RWGS) probe reaction. We introduce a novel approach to synthesize ultrathin (4-7 nm) hematite nanosheets using copper oxide nanosheets as a hard template and propose a reaction mechanism based on density functional theory (DFT) calculations. Hematite nanowires and nanoparticles were also synthesized and characterized...
September 14, 2017: Nanoscale
Shuang Jiang, Mahshid Chekini, Zhi-Bei Qu, Yichun Wang, Aydan Yeltik, Yuangang Liu, Alex Kotlyar, Tianyong Zhang, Bin Li, Hilmi Volkan Demir, Nicholas A Kotov
The chirality of nanoparticles (NPs) and their assemblies has been investigated predominantly for noble metals and II-VI semiconductors. However, ceramic NPs represent the majority of nanoscale materials in nature. The robustness and other innate properties of ceramics offer technological opportunities in catalysis, biomedical sciences, and optics. Here we report the preparation of chiral ceramic NPs, as represented by tungsten oxide hydrate, WO3-x·H2O, dispersed in ethanol. The chirality of the metal oxide core, with an average size of ca...
September 20, 2017: Journal of the American Chemical Society
Vishal J Mayani, Suranjana V Mayani, Sang Wook Kim
Up to now, a very few catalysts have been developed approaching the heterogeneous catalytic degradation of Eosin Y and Chromotrope 2R dyes (Acid Red 29). The present study provides a complete perspective of recyclable nanocomposite Au(Salen)@CC for catalytic degradation of hazardous water pollutant dyes viz., Eosin Y & Chromotrope 2R using mild reaction conditions. New gold Salen complex doped carbon nanocomposite Au(Salen)@CC was developed by easy methodology using nano carbon cage (CC) prepared from low-priced Pyrolysis fuel oil (PFO) residue based Pitch...
August 3, 2017: Scientific Reports
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