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https://www.readbyqxmd.com/read/29454058/carboxymethyl-konjac-glucomannan-crosslinked-chitosan-sponges-for-wound-dressing
#1
Yu Xie, Zeng-Xing Yi, Jian-Xun Wang, Tong-Gang Hou, Qiong Jiang
In this paper, carboxymethyl konjac glucomannan (CMKGM) was obtained by carboxyl modification of konjac glucomannan. Then CMKGM and chitosan (CS) were crosslinked and freeze-dried to prepare CMKGM/CS composite sponges with different proportions. The structure and micromorphology of CMKGM/CS sponges were investigated by FTIR spectroscopy and SEM. The SEM results showed that the pore structure of the composite sponge gradually increased with the increase of CMKGM content. To assess the applicability of CMKGM/CS composite sponges as wound dressing, the swelling behavior, water vapor transmission rate (WVTR), biocompatibility (cytotoxicity and hemolysis) were analyzed...
February 14, 2018: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/29453948/noncritical-signaling-role-of-a-kinase-receptor-interaction-surface-in-the-escherichia-coli-chemosensory-core-complex
#2
Germán E Piñas, Michael D DeSantis, John S Parkinson
In E. coli chemosensory arrays, transmembrane receptors, a histidine autokinase CheA, and a scaffolding protein CheW interact to form an extended hexagonal lattice of signaling complexes. One interaction, previously assigned a crucial signaling role, occurs between chemoreceptors and the CheW-binding P5 domain of CheA. Structural studies showed a receptor helix fitting into a hydrophobic cleft at the boundary between P5 subdomains. Our work aimed to elucidate the in vivo roles of the receptor-P5 interface, employing as a model the interaction between E...
February 14, 2018: Journal of Molecular Biology
https://www.readbyqxmd.com/read/29453807/tunable-poly-methacrylic-acid-co-acrylamide-nanoparticles-through-inverse-emulsion-polymerization
#3
Justin X Zhong, John R Clegg, Eric W Ander, Nicholas A Peppas
Environmentally responsive biomaterials have played key roles in the design of biosensors and drug delivery vehicles. Their physical response to external stimuli, such as temperature or pH, can transduce a signal or trigger the release of a drug. In this work, we designed a robust, highly tunable, pH responsive nanoscale hydrogel system. We present the design and characterization of poly((methacrylic acid) - co - acrylamide) hydrogel nanoparticles, crosslinked with methylenebisacrylamide, through inverse emulsion polymerization...
February 17, 2018: Journal of Biomedical Materials Research. Part A
https://www.readbyqxmd.com/read/29452937/epigenetic-chromatin-modification-by-amber-suppression-technology
#4
REVIEW
Heinz Neumann, Petra Neumann-Staubitz, Anna Witte, Daniel Summerer
The genetic incorporation of unnatural amino acids (UAAs) into proteins by amber suppression technology provides unique avenues to study protein structure, function and interactions both in vitro and in living cells and organisms. This approach has been particularly useful for studying mechanisms of epigenetic chromatin regulation, since these extensively involve dynamic changes in structure, complex formation and posttranslational modifications that are difficult to access by traditional approaches. Here, we review recent achievements in this field, emphasizing UAAs that help to unravel protein-protein interactions in cells by photo-crosslinking or that allow the biosynthesis of proteins with defined posttranslational modifications for studying their function and turnover in vitro and in cells...
February 13, 2018: Current Opinion in Chemical Biology
https://www.readbyqxmd.com/read/29452913/photo-immobilized-egf-chemical-gradients-differentially-impact-breast-cancer-cell-invasion-and-drug-response-in-defined-3d-hydrogels
#5
Stephanie A Fisher, Roger Y Tam, Ana Fokina, M Mohsen Mahmoodi, Mark D Distefano, Molly S Shoichet
Breast cancer cell invasion is influenced by growth factor concentration gradients in the tumor microenvironment. However, studying the influence of growth factor gradients on breast cancer cell invasion is challenging due to both the complexities of in vivo models and the difficulties in recapitulating the tumor microenvironment with defined gradients using in vitro models. A defined hyaluronic acid (HA)-based hydrogel crosslinked with matrix metalloproteinase (MMP) cleavable peptides and modified with multiphoton labile nitrodibenzofuran (NDBF) was synthesized to photochemically immobilize epidermal growth factor (EGF) gradients...
February 13, 2018: Biomaterials
https://www.readbyqxmd.com/read/29452287/dental-pulp-stem-cell-derived-chondrogenic-cells-demonstrate-differential-cell-motility-in-type-i-and-type-ii-collagen-hydrogels
#6
Li Yao, Nikol Flynn
BACKGROUND CONTEXT: Advances in the development of biomaterials and stem cell therapy provide a promising approach to regenerating degenerated discs. The normal nucleus pulposus (NP) cells exhibit the similar phenotype as chondrocytes. Because dental pulp stem cells (DPSCs) can be differentiated into chondrogenic cells, the DPSCs and DPSCs-derived chondrogenic cells encapsulated in type I and type II collagen hydrogels can potentially be transplanted into degenerated nucleus pulposus (NP) to repair damaged tissue...
February 13, 2018: Spine Journal: Official Journal of the North American Spine Society
https://www.readbyqxmd.com/read/29452274/control-of-thiol-maleimide-reaction-kinetics-in-peg-hydrogel-networks
#7
Lauren E Jansen, Lenny J Negrón-Piñeiro, Sualyneth Galarza, Shelly R Peyton
Michael-type addition reactions are widely used to polymerize biocompatible hydrogels. The thiol-maleimide modality achieves the highest macromer coupling efficiency of the reported Michael-type pairs, but the resulting hydrogel networks are heterogeneous, because polymerization is faster than the individual components can be manually mixed. The reactivity of the thiol dictates the overall reaction speed, which can be slowed in organic solvents and acidic buffers. Since these modifications also reduce the biocompatibility of resulting hydrogels, we investigated a series of biocompatible buffers and crosslinkers to decelerate gelation while maintaining high cell viability...
February 13, 2018: Acta Biomaterialia
https://www.readbyqxmd.com/read/29451983/reinforcing-mucus-barrier-properties-with-low-molar-mass-chitosans
#8
Sujit Kootala, Luimar Filho, Vaibhav Srivastava, Victoria Linderberg, Amani Moussa, Laurent David, Stéphane Trombotto, Thomas Crouzier
The mucus gel covers the wet epithelia that forms the inner lining of the body. It constitutes our first line of defense protecting the body from infections and other deleterious molecules. Failure of the mucus barrier can lead to the inflammation of the mucosa such as in inflammatory bowel diseases. Unfortunately, there are no effective strategies that reinforce the mucus barrier properties to recover or enhance its ability to protect the epithelium. Herein, we describe a mucus engineering approach that addresses this issue where we physically crosslink the mucus gel with low molar mass chitosan variants to reinforce its barrier functions...
February 16, 2018: Biomacromolecules
https://www.readbyqxmd.com/read/29451877/influence-of-hyperbaric-oxygen-on-biomechanics-and-structural-bone-matrix-in-type-1-diabetes-mellitus-rats
#9
Pedro Henrique Justino Oliveira Limirio, Huberth Alexandre da Rocha Junior, Richarlisson Borges de Morais, Karen Renata Nakamura Hiraki, Ana Paula Coelho Balbi, Priscilla Barbosa Ferreira Soares, Paula Dechichi
BACKGROUND: The aim of this study was to evaluate the biomechanics and structural bone matrix in diabetic rats subjected to hyperbaric oxygen therapy (HBO). METHODS: Twenty-four male rats were divided into the following groups: Control; Control + HBO; Diabetic, and Diabetic + HBO. Diabetes was induced with streptozotocin (STZ) in the diabetic Groups. After 30 days, HBO was performed every 48h in HBO groups and all animals were euthanized 60 days after diabetic induction...
2018: PloS One
https://www.readbyqxmd.com/read/29451572/3d-printed-scaffolds-with-gradient-porosity-based-on-a-cellulose-nanocrystal-hydrogel
#10
Sahar Sultan, Aji P Mathew
3-Dimensional (3D) printing provides a unique methodology for the customization of biomedical scaffolds with respect to size, shape, pore structure and pore orientation useful for tissue repair and regeneration. 3D printing was used to fabricate fully bio-based porous scaffolds of a double crosslinked interpenetrating polymer network (IPN) from a hydrogel ink of sodium alginate and gelatin (SA/G) reinforced with cellulose nanocrystals (CNCs). CNCs provided favorable rheological properties required for 3D printing...
February 16, 2018: Nanoscale
https://www.readbyqxmd.com/read/29451384/a-highly-elastic-biodegradable-single-network-hydrogel-for-cell-printing
#11
Cancan Xu, Wenhan Lee, Guohao Dai, Yi Hong
Cell printing is becoming a common technique to fabricate cellularized printed-scaffold for biomedical application. There are still significant challenges in soft tissue bioprinting using hydrogels which requires live cells inside the hydrogels. Moreover, the resilient mechanical properties from hydrogels are also required to mechanically mimic the native soft tissues. Herein, we developed a visible-light crosslinked, single-network, biodegradable hydrogel with high elasticity and flexibility for cell printing, which is different from previous highly elastic hydrogel with double-network and two-components...
February 16, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29448723/preparation-of-nanoscale-zinc-oxide-laponite-composites-by-polyvinyl-alcohol-polymerization-and-usability-for-removal-of-trichloroethylene-in-water
#12
Jong Kyu Kim, Hosang Ahn, Jong-Ho Kim, Yang-Jin Ban, Keugtae Kim, Jin Chul Joo
Innovative nanoscale ZnO-laponite-polyvinyl alcohol composites (NZLPc) were developed as a valid alternative to nanoscale photocatalysts for mineralization of chlorinated hydrocarbons without difficulties in recovery of nanoscale photocatalyst particles. NZLPc were synthesized by mixing nanoscale ZnO particles with laponite in PVA solution, and by crosslinking PVA solution in the presence of boric acid (≥1.6 M). Different mixing ratios of the raw materials were investigated to develop the stable NZLPc, and X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy characterizations were performed...
March 1, 2018: Journal of Nanoscience and Nanotechnology
https://www.readbyqxmd.com/read/29448654/fabrication-of-acf-go-pei-composite-for-adsorption-of-methyl-orange-from-aqueous-solution
#13
Liping Wang, Mingyu Zhang, Qizhong Huang, Chenxi Zhao, Kun Luo, Min Lei
ACF/GO/PEI (activated carbon fiber/graphene oxide/polyethyleneimine) composite was fabricated by crosslinking reaction and characterized with Scanning electron microscope (SEM), N2 physical adsorption and Fourier transform infrared spectroscopy (FTIR). Furthermore, the adsorption behavior of ACF/GO/PEI composite for methyl orange (MO) from aqueous solution was investigated. The experimental results showed that the specific surface area of ACF/GO/PEI composite is 1013.6 m2/g and almost the same as that of original ACFs...
March 1, 2018: Journal of Nanoscience and Nanotechnology
https://www.readbyqxmd.com/read/29448642/nanocomposite-membranes-comprising-crosslinked-polymer-blends-of-poly-vinyl-alcohol-poly-styrene-sulfonic-acid-co-maleic-acid-and-fumed-silica-nanoparticles
#14
Moon-Sung Kang, Yong Soo Kang, Hyoung-Juhn Kim, Hak-Soo Han, Jin-Soo Park
Nanocomposite polymer electrolyte membranes comprising a crosslinked polymer blend of poly(vinyl alcohol)/poly(styrene sulfonic acid-co-maleic acid) (PVA/PSSA-co-MA) and fumed silica nanoparticles were prepared for direct methanol fuel cell (DMFC) applications. Silica nanoparticles could be incorporated well uniformly in the completely miscible system, which can form a three-dimensional network structure to achieve the enhancement of mechanical properties as well as the additional reduction of methanol permeability...
March 1, 2018: Journal of Nanoscience and Nanotechnology
https://www.readbyqxmd.com/read/29448630/dynamic-and-depth-dependent-nanomechanical-properties-of-dorsal-ruffles-in-live-cells-and-biopolymeric-hydrogels
#15
Varun Vyas, Melani Solomon, Gerard G M D'Souza, Bryan D Huey
The nanomechanical properties of various biological and cellular surfaces are increasingly investigated with Scanning Probe Microscopy. Surface stiffness measurements are currently being used to define metastatic properties of various cancerous cell lines and other related biological tissues. Here we present a unique methodology to understand depth dependent nanomechanical variations in stiffness in biopolymers and live cells. In this study we have used A2780 and NIH3T3 cell lines and 0.5% and 1% Agarose to investigate depth dependent stiffness and porosity on nanomechanical properties in different biological systems...
March 1, 2018: Journal of Nanoscience and Nanotechnology
https://www.readbyqxmd.com/read/29447965/simple-fabrication-of-chitosan-graphene-nanoplates-composite-spheres-for-efficient-adsorption-of-acid-dyes-from-aqueous-solution
#16
Conglu Zhang, Zezhi Chen, Wei Guo, Chengwu Zhu, Yajie Zou
A facile method for the fabrication of crosslinked chitosan/graphene nanoplates composite sphere (CS/GNPs) was presented. The obtained samples were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopic (XPS) and thermogravimetric analysis (TGA). The adsorption activities of CS/GNPs for methyl orange (MO) and acid red 1 (AR1) were evaluated such as the effect of pH and GNPs content, as well as adsorption kinetics and isotherms. In view of practical, the reusability of CS/GNPs was also tested...
February 12, 2018: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/29447960/mechanically-enhanced-nested-network-hydrogels-as-a-coating-material-for-biomedical-devices
#17
Zhengmu Wang, Hongbin Zhang, Axel J Chu, John Jackson, Karen Lin, Chinten James Lim, Dirk Lange, Mu Chiao
Well-organized composite formations such as hierarchical nested-network (NN) structure in bone tissue and reticular connective tissue present remarkable mechanical strength and play a crucial role in achieving physical and biological functions for living organisms. Inspired by these delicate microstructures in nature, an analogous scaffold of double network hydrogel was fabricated by creating a poly(2-hydroxyethyl methacrylate) (pHEMA) network in the porous structure of alginate hydrogels. The resulting hydrogel possessed hierarchical NN structure and showed significantly improved mechanical strength but still maintained high elasticity comparable to soft tissues due to a mutual strengthening effect between the two networks...
February 12, 2018: Acta Biomaterialia
https://www.readbyqxmd.com/read/29447665/preparation-of-molecularly-imprinted-polymer-nanobeads-for-selective-sensing-of-carboxylic-acid-vapors
#18
Chuanjun Liu, Liang Shang, Hiro-Taka Yoshioka, Bin Chen, Kenshi Hayashi
The detection and discrimination of volatile carboxylic acid components, which are the main contributors to human body odor, have a wide range of potential applications. Here, a quartz crystal microbalance (QCM) sensor array based on molecularly imprinted polymer (MIP) nanobeads is developed for highly sensitive and selective sensing of typical carboxylic acid vapors, namely: propionic acid (PA), hexanoic acid (HA) and octanoic acid (OA). The MIP nanobeads were prepared by precipitation polymerization with methacrylic acid (MAA) as a functional monomer, trimethylolproane trimethacrylate (TRIM) as a crosslinker, and carboxylic acids (PA, HA and OA) as the template molecules...
June 20, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29446622/hyper-crosslinked-porous-mos2-cyclodextrin-polymer-frameworks-rapid-and-durable-removal-of-aromatic-phenolic-micropollutant-from-water
#19
Jian Liu, Yanmei Yang, Jinwei Bai, Huang Wen, Fengjuan Chen, Baodui Wang
A reasonable and efficient strategy for the construction of hyper-crosslinked porous MoS2-CD-polymer frameworks (MoS2CDPFs) was demonstrated. Here, MoS2 nanosheets (NSs) can be decorated with amino functionalized β-Cyclodextrin, giving rise to a nanoscale structural motif (MoS2@CD) for the synthesis of MoS2CDPFs. We demonstrated that CD polymer (CDP) can be acted as linker and uniformly incorporated into the frameworks. In addition to the pores created between MoS2 NSs, polymer doping generates extra interspace between MoS2 NSs and CD monomer...
February 15, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/29446165/synthetic-transient-crosslinks-program-the-mechanics-of-soft-biopolymer-based-materials
#20
Jessica S Lorenz, Jörg Schnauß, Martin Glaser, Martin Sajfutdinow, Carsten Schuldt, Josef A Käs, David M Smith
Actin networks are adaptive materials enabling dynamic and static functions of living cells. A central element for tuning their underlying structural and mechanical properties is the ability to reversibly connect, i.e., transiently crosslink, filaments within the networks. Natural crosslinkers, however, vary across many parameters. Therefore, systematically studying the impact of their fundamental properties like size and binding strength is unfeasible since their structural parameters cannot be independently tuned...
February 15, 2018: Advanced Materials
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