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Mengfan Zhai, Feng Ma, Junying Li, Binbin Wan, Ning Yu
A novel supermacroporous poly(hydroxypropyl methacrylate) (p(HPMA)) cryogel was synthesized by cryogelation method at -16 °C. In this synthesis process, HPMA was used as a monomer, and N,N'-methylenebisacrylamide (MBAAm) was used as cross-linker; the reaction was carried out in the presence of redox initiator pair N,N,N',N'-tetramethylene diamine (TEMED) and ammonium persulfate (APS). The effect of monomer concentration, cross-linker content, cooling rate, and dioxane co-solvent were determined with respect to the pore structure, mechanical behavior, swelling degree, and porosity of cryogel...
April 18, 2018: Journal of Biomaterials Science. Polymer Edition
Yang Wang, Qi Liu, Qin Zhang, Bosi Peng, Hexiang Deng
We report a new approach to create metal-binding site in a series of metal-organic frameworks (MOFs), where tetra-topic carboxylate linker, 4',4'',4''',4''''-methanetetrayltetrabiphenyl-4-carboxylic acid, is partially replaced by a tri-topic carbox-ylate linker, tris(4-carboxybiphenyl)amine, in combination with mono-topic linkers, formic acid, trifluoroacetic acid, ben-zoic acid, isonicotinic acid, 4-chlorobenzoic acid, and 4-nitrobenzoic acid, respectively. The distance between these paired-up linkers can be precisely controlled, ranging from 5...
April 18, 2018: Angewandte Chemie
Ivan Nikolaevich Meshkov, Alexandra Igorevna Zvyagina, Andrey A Shiryaev, Maximilian Sergeevich Nickolsky, Alexander E Baranchikov, Alexander A Ezhov, Alsu Nugmanova, Yulia Yu Enakieva, Yulia Germanovna Gorbunova, Vladimir Valentinovich Arslanov, Maria A Kalinina
Porphyrin-based metal-organic networks on surfaces are a new class of planar materials with promising features for applications in chemical sensing, catalysis and organic optoelectronics at nanoscale. Herein we studied systematically a series of the SURMOFs assembled from variously meso-carboxyphenyl/pyridyl substituted porphyrins and zinc acetate on template monolayers of graphene oxide via layer-by-layer deposition. This microscopically flat template can initiate the growth of macroscopically uniform SURMOF films exhibiting well-resolved X-ray diffraction...
April 18, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Shixin Fang, Guangjian Wang, Pengcheng Li, Ronge Xing, Song Liu, Yukun Qin, Huahua Yu, Xiaolin Chen, Kecheng Li
A new superabsorbent polymer was synthesized using amino ethyl chitosan and an acrylic acid by a free radical polymerization. The chemical structure of the superabsorbent polymer was characterized using FTIR, TGA, XRD and solid-state 13 C NMR. The results revealed that the acrylic acid was successfully grafted onto the amino ethyl chitosan backbone. As revealed by SEM, a surface with homogeneous and interconnected pore structure was obtained. The influences of different factors (e.g., the initiator, cross-linker and monomer) on the water absorbency of the superabsorbent polymers were investigated...
April 14, 2018: International Journal of Biological Macromolecules
Ankita Gupta, Ramasubbu Sankararamakrishnan
SWEET (Sweet Will Eventually be Exported Transporter) proteins have been recently discovered and form one of the three major families of sugar transporters. Homologs of SWEET are found in both prokaryotes and eukaryotes. Bacterial SWEET homologs have three transmembrane segments forming a triple-helical bundle (THB) and the functional form is dimers. Eukaryotic SWEETs have seven transmembrane helical segments forming two THBs with a linker helix. Members of SWEET homologs have been shown to be involved in several important physiological processes in plants...
April 14, 2018: Journal of Molecular Biology
Juneyoung Lee, Jeong Hoon Ko, Kathryn M Mansfield, Peter C Nauka, Erhan Bat, Heather D Maynard
Effective delivery of therapeutic proteins is important for many biomedical applications. Yet, the stabilization of proteins during delivery and long-term storage remains a significant challenge. Herein, a trehalose-based hydrogel is reported that stabilizes insulin to elevated temperatures prior to glucose-triggered release. The hydrogel is synthesized using a polymer with trehalose side chains and a phenylboronic acid end-functionalized 8-arm poly(ethylene glycol) (PEG). The hydroxyls of the trehalose side chains form boronate ester linkages with the PEG boronic acid cross-linker to yield hydrogels without any further modification of the original trehalose polymer...
April 17, 2018: Macromolecular Bioscience
Frédéric Taran, Margaux Riomet, Elodie Decuypere, Karine Porte, Sabrina Bernard, Lucie Plougastel, Sergii Kolodych, Davide Audisio
Emerging applications in the field of chemical biology are currently limited by the lack of bioorthogonal reactions allowing both removal and linkage of chemical entities on complex biomolecules. We recently discovered a novel reaction between iminosydnones and strained alkynes leading to two products resulting from ligation and fragmentation of iminosydnones under physiological conditions. We now report the synthesis of a panel of substituted iminosydnones and the structure reactivity relationship between these compounds and strained alkyne partners...
April 17, 2018: Chemistry: a European Journal
Zhao-Sheng Zhang, Yun-Zhen Huang, Jian Luo, Bing-Feng Wang, Zhen Jin, Ya-Hong Liu, You-Zhi Tang
BACKGROUND: Methicillin resistant Staphylococcus aureus (MRSA) usually invalidate powerful antibiotics in the clinic. Pleuromutilin derivatives have been reported possess antibacterial activity against MRSA. OBJECTIVE: The antibacterial activities against MRSA of a series of thirteen synthetic pleuromutilin derivatives were investigated through in vitro models. METHODS: A series of novel thioehter pleuromutilin derivatives incorporating various aromatic substituents into the C14 side chain have been reported...
April 16, 2018: Medicinal Chemistry
Shangjing Xin, Omar M Wyman, Daniel L Alge
The assembly of microgel building blocks into 3D scaffolds is an emerging strategy for tissue engineering. A key advantage is that the inherent microporosity of these scaffolds provides cells with a more permissive environment than conventional nanoporous hydrogels. Here, norbornene-bearing poly(ethylene glycol) (PEG) based microgels are assembled into 3D cell-instructive scaffolds using a PEG-dithiol linker and thiol-ene click photopolymerization. The bulk modulus of these materials depends primarily on the crosslink density of the microgel building blocks...
April 16, 2018: Advanced Healthcare Materials
Yoon-Hui Sung, David Eliezer
The Parkinson's protein alpha-synuclein binds to synaptic vesicles in vivo and adopts a highly extended helical conformation when binding to lipid vesicles in vitro. High-resolution structural analysis of alpha-synuclein bound to small lipid or detergent micelles revealed two helices connected by a non-helical linker, but corresponding studies of the vesicle-bound extended-helix state are hampered by the size and heterogeneity of the protein-vesicle complex. Here we employ fluorinated alcohols (FAs) to induce a highly helical aggregation-resistant state of alpha-synuclein in solution that resembles the vesicle-bound extended-helix state but is amenable to characterization using high-resolution solution-state NMR...
April 16, 2018: Protein Science: a Publication of the Protein Society
Navid Hakimi, Richard Cheng, Lian Leng, Mohammad Sotoudehfar, Phoenix Qing Ba, Nazihah Bakhtyar, Saeid Amini-Nik, Marc G Jeschke, Axel Günther
We present a handheld skin printer that enables the in situ formation of biomaterial and skin tissue sheets of different homogeneous and architected compositions. When manually positioned above a target surface, the compact instrument (weight <0.8 kg) conformally deposits a biomaterial or tissue sheet from a microfluidic cartridge. Consistent sheet formation is achieved by coordinating the flow rates at which bioink and cross-linker solution are delivered, with the speed at which a pair of rollers actively translate the cartridge along the surface...
April 17, 2018: Lab on a Chip
Khalid Hussain Thebo, Xitang Qian, Qing Zhang, Long Chen, Hui-Ming Cheng, Wencai Ren
Increasing fresh water demand for drinking and agriculture is one of the grand challenges of our age. Graphene oxide (GO) membranes have shown a great potential for desalination and water purification. However, it is challenging to further improve the water permeability without sacrificing the separation efficiency, and the GO membranes are easily delaminated in aqueous solutions within few hours. Here, we report a class of reduced GO membranes with enlarged interlayer distance fabricated by using theanine amino acid and tannic acid as reducing agent and cross-linker...
April 16, 2018: Nature Communications
Motoki Takeda, Satoru Hiroto, Hiroki Yokoi, Sangsu Lee, Dongho Kim, Hiroshi Shinokubo
We designed and synthesized molecular tweezers consisted of nitrogen-embedded buckybowl subunits. The judicious choice of the covalent linkers modulated their binding strength with C60 or C70 in solution. Titration studies by optical and 1 H NMR analysis revealed a 1:1 composition of the resulting complexes. X-Ray diffraction analysis elucidated their solid-state structures in which two azabuckybowl units surround one molecule of fullerenes. The large association constants stabilize the complexes under redox reactions and purification process on silica-gel column chromatography...
April 17, 2018: Journal of the American Chemical Society
Pil Seok Chae, Muhammad Ehsan, Manabendra Das, Valerie Stern, Yang Du, Jonas Mortensen, Parameswaran Hariharan, Bernadette Byrne, Claus Loland, Brian Kobilka, Lan Guan
Membrane proteins allow effective communication between cells and organelles and their external environments. Maintaining membrane protein stability in a non-native environment is the major bottleneck to their structural study. Detergents are widely used to extract membrane proteins from the membrane and keep the extracted protein in a stable state for downstream characterization. In the current study, three sets of steroid-based amphiphiles, glyco-diosgenin analogs (GDNs), steroid-based penta-saccharides either lacking a linker (SPSs) or with a linker (SPS-Ls), were developed as novel chemical tools for membrane protein research...
April 16, 2018: Chembiochem: a European Journal of Chemical Biology
Claudio Iacobucci, Mathias Schäfer, Andrea Sinz
Free radical-initiated peptide sequencing (FRIPS) has recently been introduced as an analytical strategy to create peptide radical ions in a predictable and effective way by collisional activation of specifically modified peptides ions. FRIPS is based on the unimolecular dissociation of open-shell ions and yields fragments that resemble those obtained by electron capture dissociation (ECD) or electron transfer dissociation (ETD). In this review article, we describe the fundamentals of FRIPS and highlight its fruitful combination with chemical cross-linking/mass spectrometry (MS) as a highly promising option to derive complementary structural information of peptides and proteins...
April 16, 2018: Mass Spectrometry Reviews
Feng Gao, Wiebke Sihver, Ralf Bergmann, Birgit Belter, Cristina Bolzati, Nicola Salvarese, Jörg Steinbach, Jens Pietzsch, Hans-Jürgen Pietzsch
α-Melanocyte stimulating hormone (α-MSH) derivatives target the melanocortin-1 receptor (MC1R) specifically and selectively. In this study, the α-MSH derived peptide NAP-NS1 (Nle-Asp-His-D-Phe-Arg-Trp-Gly-NH2) with and without linkers was conjugated with 5-(bis(pyridin-2-yl)methyl)amino)pentanoic acid (DPA-COOH) and labeled with [99mTc]Tc-tricarbonyl by two methods. With the one-pot method the labeling was faster than with the two-pots method, however obtaining similarly high yields. Negligible transchelation and high stability in physiological solutions was determined for the [99mTc]Tc-tricarbonyl-peptide conjugates...
April 16, 2018: ChemMedChem
E A Fedorova, T A Smolonogina, I N Isakova-Sivak, D A Koren'kov, T S Kotomina, G F Leont'eva, A N Suvorov, L G Rudenko
A project of an experimental recombinant vector vaccine for prevention of diseases caused by pathogenic streptococci based on ScaAB lipoprotein of Streptococcus agalactiae and a coldadapted strain of live influenza vaccine as a vector was developed. The sequence of ScaAB lipoprotein was analyzed and fragments forming immunodominant epitopes were determined. Chimeric molecules of influenza virus hemagglutinin H7 carrying insertions of bacterial origin were constructed. Based on the results of simulation, the most promising variants were selected; they represented fragments of lipoprotein ScaAB lacking N-terminal domain bound to hemagglutinin via a flexible linker...
April 16, 2018: Bulletin of Experimental Biology and Medicine
Huimin Yang, Xu Zhang, Guiyang Zhang, Honghan Fei
An alkaline-resistant Ag(i)-anchored metal-organic framework has been achieved via postsynthetic modification of pyrazolate-based linkers. For the first time, the resultant MOF was completely heterogeneous and recyclable over at least ten cycles in cyclic carboxylation of propargyl amines and CO2 into oxazolidinones and tetramic acids under atmospheric pressure of CO2.
April 16, 2018: Chemical Communications: Chem Comm
Emmanouil Nikoloudakis, Kostas Karikis, Maxime Laurans, Chrysoula Kokotidou, Albert Solé-Daura, Jorge J Carbó, Asterios Charisiadis, Georgios Charalambidis, Guillaume Izzet, Anna Mitraki, Antonios M Douvas, Josep M Poblet, Anna Proust, Athanassios G Coutsolelos
Herein, we report on the study of supramolecular assemblies based on polyoxometalates (POMs) upon their modification with amino acids. Two POM-amino acid hybrids were synthesized by coupling a functionalized Keggin type polyoxoanion [PW11O39{Sn(C6H4)C[triple bond, length as m-dash]C(C6H4)COOH}]4- with carboxyl-protected (methyl-ester) phenylalanine or diphenylalanine peptides. Surprisingly, all compounds, including the initial POM, formed supramolecular nanospheres in different solvent mixtures, which were examined by scanning electron microscopy (SEM)...
April 16, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Yaoqi Wang, Xing Wang, Feiyang Deng, Nan Zheng, Yanqin Liang, Hua Zhang, Bing He, Wenbing Dai, Xueqing Wang, Qiang Zhang
Drug-drug conjugate nanoparticles (DDC NPs) is a potential method for overcoming poor solubility and nonspecific action in cancer therapy, which is based on its high drug loading efficiency and passive tumor-target properties. Our laboratory has prepared DOX-SS-DOX NPs based on disulfide-linked doxorubicin (DOX) drug-drug conjugate, which showed well physical stability and similar anti-tumor efficacy as liposomes. However, how structures of DDCs influence the self-assembling and anti-tumor efficacy is still seldom clarified and needs further investigation...
April 12, 2018: Journal of Controlled Release: Official Journal of the Controlled Release Society
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