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https://www.readbyqxmd.com/read/28350965/on-monolayer-formation-of-pyrenebutyric-acid-on-graphene
#1
Malkolm Hinnemo, Jie Zhao, Patrik Ahlberg, Carl Hägglund, Viktor Djurberg, Ralph H Scheicher, Shi-Li Zhang, Zhibin Zhang
As a two-dimensional material with high charge carrier mobility, graphene may offer ultrahigh sensitivity in bio-sensing. In order to realize this, the first step is to functionalize the graphene. This is commonly done by using 1-pyrenebutyric acid (PBA) as a linker for biomolecules. However, the adsorption of PBA on graphene remains poorly understood despite reports of successful biosensor functionalized via this route. Here, the PBA adsorption on graphene is characterized through a combination of Raman spectroscopy, ab initio calculations, and spectroscopic ellipsometry...
March 28, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28350451/ros-switchable-polymeric-nanoplatform-with-stimuli-responsive-release-for-active-targeted-drug-delivery-to-breast-cancer
#2
Yu Zhang, Qin Guo, Sai An, Yifei Lu, Jianfeng Li, Xi He, Lisha Liu, Yujie Zhang, Tao Sun, Chen Jiang
Tumor microenvironment plays a vital role in the process of tumor development, proliferation, invasion, and metastasis. It is well acknowledged that reduction in pH, reactive oxygen species (ROS), and increased level of glucose transporter 1 (GLUT1) have become featured intracellular and extracellular biochemical markers of cancer owing to oncogenic transformation and abnormal metabolism. To establish a distinctive drug delivery system directed against the tumor microenvironment features, we develop a newly engineered polymeric nanoplatform for efficient doxorubicin (DOX) delivery with reduced systemic toxicity and high antitumor efficiency...
March 28, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28350434/stepwise-synthesis-of-metal-organic-frameworks
#3
Mathieu Bosch, Shuai Yuan, William Rutledge, Hong-Cai Zhou
Metal-organic frameworks (MOFs) are a category of porous materials that offer unparalleled control over their surface areas (demonstrated as higher than for any other material), pore characteristics, and functionalization. This allows them to be customized for exceptional performance in a wide variety of applications, most commonly including gas storage and separation, drug delivery, luminescence, or heterogeneous catalysis. In order to optimize biomimicry, controlled separations and storage of small molecules, and detailed testing of structure-property relationships, one major goal of MOF research is "rational design" or "pore engineering", or precise control of the placement of multiple functional groups in pores of chosen sizes and shapes...
March 28, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28346786/break-down-in-order-to-build-up-decomposing-small-molecules-for-fragment-based-drug-design-with-emolfrag
#4
Tairan Liu, Misagh Naderi, Chris Alvin, Supratik Mukhopadhyay, Michal Brylinski
Constructing high-quality libraries of molecular building blocks is essential for successful fragment-based drug discovery. In this communication, we describe eMolFrag, a new open-source software to decompose organic compounds into non-redundant fragments retaining molecular connectivity information. Given a collection of molecules, eMolFrag generates a set of unique fragments comprising larger moieties, bricks, and smaller linkers connecting bricks. These building blocks can subsequently be used to construct virtual screening libraries for targeted drug discovery...
March 27, 2017: Journal of Chemical Information and Modeling
https://www.readbyqxmd.com/read/28346732/asiaticoside-hinders-the-invasive-growth-of-keloid-fibroblasts-through-inhibition-of-the-gdf-9-mapk-smad-pathway
#5
Xin Wu, Difei Bian, Yannong Dou, Zhunan Gong, Qian Tan, Yufeng Xia, Yue Dai
Higher expression of growth differentiation factor-9 (GDF-9) in keloids compared with hypertrophic scars and normal skin tissues has been reported recently. The present study was performed to investigate the role of GDF-9 in keloid pathogenesis, and to elucidate its implication for asiaticoside in the keloid management. The data showed that GDF-9 could enhance the proliferation, migration, and invasion of keloid fibroblasts (KFs), while it only slightly elevated collagen expression, indicating that the effect of GDF-9 was opposite to that of TGF-β1...
March 27, 2017: Journal of Biochemical and Molecular Toxicology
https://www.readbyqxmd.com/read/28346376/blend-hydrogel-microspheres-of-carboxymethyl-chitosan-and-gelatin-for-the-controlled-release-of-5-fluorouracil
#6
Vanarchi Rajini Kanth, Praveen B Kajjari, Priya M Madalageri, Sakey Ravindra, Lata S Manjeshwar, Tejraj M Aminabhavi
Carboxymethyl chitosan (CMCS) was synthesized and blended with gelatin (GE) to prepare hydrogel microspheres by w/o emulsion cross-linking in the presence of glutaraldehyde (GA), which acted as a cross-linker. 5-Fluorouracil (5-FU) was encapsulated to investigate its controlled release (CR) characteristics in acidic (pH 1.2) and alkaline (pH 7.4) buffer media. The microspheres which formed were spherical in nature, with smooth surfaces, as judged by the scanning electron microscopy (SEM). Fourier transform infrared spectroscopy (FTIR) confirmed the carboxymethylation of CS and the chemical stability of 5-FU in the formulations...
March 27, 2017: Pharmaceutics
https://www.readbyqxmd.com/read/28345925/metal-insertion-in-a-methylamine-functionalized-zirconium-metal-organic-framework-for-enhanced-carbon-dioxide-capture
#7
A Paulina Gómora-Figueroa, Jarad A Mason, Miguel I Gonzalez, Eric D Bloch, Katie R Meihaus
The reaction of ZrCl4 with 2',3',5',6'-tetramethylamino-p-terphenyl-4,4″-dicarboxylic acid (H2tpdc-4CH2NH2·3HCl) in the presence of NaF affords Zr6O4(OH)2.1F1.9(tpdc-4CH2NH2·3HCl)6 (1), which is a new member of the Zr6O4(OH)4(dicarboxylate linker)12 or UiO-68 family, and exhibits high porosity with BET and Langmuir surface areas of 1910 m(2)/g and 2220 m(2)/g, respectively. Remarkably, fluoride ion incorporation in the zirconium clusters results in increased thermal stability, marking the first example of enhancement in the stability of a UiO framework by this defect-restoration approach...
March 27, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28345916/molecular-mechanism-of-nucleotide-dependent-allosteric-regulation-in-amp-activated-protein-kinase
#8
Navjeet Ahalawat, Rajesh Kumar Murarka
The AMP-activated protein kinase (AMPK), a central enzyme in the regulation of energy homeostasis, is an important drug target for type 2 diabetes, obesity and cancer. Binding of adenosine nucleotides to the regulatory γ-subunit tightly regulates the activity of this enzyme. Though recent crystal structures of AMPK have provided important insights into the allosteric activation of AMPK, molecular details of the regulatory mechanism of AMPK activation is still elusive. Here, we have performed extensive all-atom molecular dynamics (MD) simulations and shown that the kinase domain (KD) and γ-subunit comes closer resulting in a more compact heterotrimeric AMPK complex in AMP-bound state compared to the ATP-bound state...
March 27, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28345882/covalent-allosteric-inactivation-of-ptp1b-by-an-inhibitor-electrophile-conjugate
#9
Puminan Punthasee, Adrian R Laciak, Andrea Hicks Cummings, Kasi Viswanatharaju Ruddraraju, Sarah M Lewis, Roman Hillebrand, Harkewal Singh, John J Tanner, Kent S Gates
Protein tyrosine phosphatase 1B (PTP1B) is a validated drug target but it has proven difficult to develop medicinally-useful, reversible inhibitors of this enzyme. Here we explored covalent strategies for the inactivation of PTP1B using a conjugate composed of an active site-directed 5-aryl-1,2,5-thiadiazolidin-3-one 1,1-dioxide inhibitor connected via a short linker to an electrophilic α-bromoacetamide moiety. The inhibitor-electrophile conjugate 5a caused time-dependent loss of PTP1B activity consistent with a covalent inactivation mechanism...
March 27, 2017: Biochemistry
https://www.readbyqxmd.com/read/28345881/silane-and-germane-molecular-electronics
#10
Timothy A Su, Haixing Li, Rebekka S Klausen, Nathaniel T Kim, Madhav Neupane, James L Leighton, Michael L Steigerwald, Latha Venkataraman, Colin Nuckolls
This Account provides an overview of our recent efforts to uncover the fundamental charge transport properties of Si-Si and Ge-Ge single bonds and introduce useful functions into group 14 molecular wires. We utilize the tools of chemical synthesis and a scanning tunneling microscopy-based break-junction technique to study the mechanism of charge transport in these molecular systems. We evaluated the fundamental ability of silicon, germanium, and carbon molecular wires to transport charge by comparing conductances within families of well-defined structures, the members of which differ only in the number of Si (or Ge or C) atoms in the wire...
March 27, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28345694/metal-organic-frameworks-for-the-removal-of-toxic-industrial-chemicals-and-chemical-warfare-agents
#11
REVIEW
N Scott Bobbitt, Matthew L Mendonca, Ashlee J Howarth, Timur Islamoglu, Joseph T Hupp, Omar K Farha, Randall Q Snurr
Owing to the vast diversity of linkers, nodes, and topologies, metal-organic frameworks can be tailored for specific tasks, such as chemical separations or catalysis. Accordingly, these materials have attracted significant interest for capture and/or detoxification of toxic industrial chemicals and chemical warfare agents. In this paper, we review recent experimental and computational work pertaining to the capture of several industrially-relevant toxic chemicals, including NH3, SO2, NO2, H2S, and some volatile organic compounds, with particular emphasis on the challenging issue of designing materials that selectively adsorb these chemicals in the presence of water...
March 27, 2017: Chemical Society Reviews
https://www.readbyqxmd.com/read/28345343/electronic-and-steric-optimization-of-fluorogenic-probes-for-biomolecular-imaging
#12
Wen Chyan, Henry R Kilgore, Brian Gold, Ronald T Raines
Fluorogenic probes are invaluable tools for spatiotemporal investigations within live cells. In common fluorogenic probes, the intrinsic fluorescence of a small-molecule fluorophore is masked by esterification until entry into a cell, where endogenous esterases catalyze the hydrolysis of the masking groups, generating fluorescence. The susceptibility of masking groups to spontaneous hydrolysis is a major limitation of these probes. Previous attempts to address this problem have incorporated auto-immolative linkers at the cost of atom economy and synthetic adversity...
March 27, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28344321/broad-spectrum-antiviral-activity-for-paramyxoviruses-is-modulated-by-biophysical-properties-of-fusion-inhibitory-peptides
#13
Cyrille Mathieu, Marcelo T Augusto, Stefan Niewiesk, Branka Horvat, Laura M Palermo, Giuseppina Sanna, Silvia Madeddu, Devra Huey, Miguel A R B Castanho, Matteo Porotto, Nuno C Santos, Anne Moscona
Human paramyxoviruses include global causes of lower respiratory disease like the parainfluenza viruses, as well as agents of lethal encephalitis like Nipah virus. Infection is initiated by viral glycoprotein-mediated fusion between viral and host cell membranes. Paramyxovirus viral fusion proteins (F) insert into the target cell membrane, and form a transient intermediate that pulls the viral and cell membranes together as two heptad-repeat regions refold to form a six-helix bundle structure that can be specifically targeted by fusion-inhibitory peptides...
March 8, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28344094/controlled-release-of-antibiotic-amoxicillin-drug-using-carboxymethyl-cellulose-cl-poly-itaconic-acid-co-lactic-acid-hydrogel
#14
S Sood, Vinod Kumar Gupta, Shilpi Agarwal, Kamal Dev, Deepak Pathania
In this paper, microwave assisted preparation of carboxymethyl cellulose-cl-poly(lactic acid-co-itaconic acid) (CMC-cl-P(LA-co-IA)) hydrogel was reported via facile graft copolymerization using N, N(1)-methylene-bis-acrylamide (MBA) and potassium persulphate as cross linker and initiator. Different reaction parameters were optimized to achieve good yield. The formation of hydrogel was confirmed by characterization techniques such as Fourier transform infrared spectroscopy, field emission scanning electron microscopy, X-ray diffraction, thermo gravimetric analysis, transmission electron microscopy etc...
March 23, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28343994/revelation-of-the-dynamic-progression-of-hypoxia-reoxygenation-injury-by-visualization-of-the-lysosomal-hydrogen-peroxide
#15
Yuanjun Zhu, Tongliang Zhou, Lingfei Yang, Lan Yuan, Lei Liang, Ping Xu
Hydrogen peroxide (H2O2) plays an important role in pathological conditions, such as cerebral ischemia-reperfusion (I-R) injury. Fluorescent probes may serve as valuable tools to detect the amount, temporal and spatial distribution of H2O2 in living cells. To investigate the role of lysosomal H2O2 involved in cerebral I-R injury, we designed and synthesized a lysosome-targetable two-photon fluorescent probe ztl-4, through expansion and substitution of the original pyridazinone scaffold, conjugation of electronic-donating aromatic ring and precise terminal modification of the alkyl linker...
March 24, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28343375/foxo1-suppression-is-a-determinant-of-acquired-lapatinib-resistance-in-her2-positive-gastric-cancer-cells-through-met-upregulation
#16
Jinju Park, Yiseul Choi, Young San Ko, Younghoon Kim, Jung-Soo Pyo, Bo Gun Jang, Min A Kim, Jae-Seon Lee, Mee Soo Chang, Jong-Wan Park, Byung Lan Lee
Purpose: Lapatinib is a candidate drug for treatment of trastuzumab-resistant, HER2-positive gastric cancer (GC). Unfortunately, lapatinib resistance renders this drug ineffective. The present study investigated the implication of forkhead box protein O1 (FOXO1) signaling in the acquired lapatinib resistance in HER2-positive GC cells. Materials and Methods: Lapatinib-resistant GC cell lines (SNU-216 LR2-8) were generated in vitro by chronic exposure of lapatinib-sensitive, HER2-positive SNU-216 cells to lapatinib...
March 24, 2017: Cancer Research and Treatment: Official Journal of Korean Cancer Association
https://www.readbyqxmd.com/read/28341402/inhibitors-of-protein-arginine-deiminases-and-their-efficacy-in-animal-models-of-multiple-sclerosis
#17
Amit Sarswat, Ewa Wasilewski, Sai K Chakka, Angelica M Bello, Andrew V Caprariello, Chithra M Muthuramu, Peter K Stys, Shannon E Dunn, Lakshmi P Kotra
Protein arginine deiminases (PAD) are implicated in a variety of inflammatory and neurodegenerative diseases including multiple sclerosis (MS). Following the discovery of an in silico hit containing hydantoin and a piperidine moiety, we hypothesized that a 2-carbon linker on the hydantoin would be necessary for a 5-membered heterocycle for optimal PAD inhibitory activity. We designed thirteen compounds as potential inhibitors of PAD2 and PAD4 enzymes-two important PAD enzymes implicated in MS. Two compounds, one with an imidazole moiety (22) and the other with a tetrazole moiety (24) showed good inhibition of PAD isozymes in vitro and in the EAE mouse model of MS in vivo...
March 6, 2017: Bioorganic & Medicinal Chemistry
https://www.readbyqxmd.com/read/28340737/efficient-extraction-of-low-abundance-peptides-from-digested-proteins-and-simultaneous-exclusion-of-large-sized-proteins-with-novel-hydrophilic-magnetic-zeolitic-imidazolate-frameworks
#18
Man Zhao, Yiqin Xie, Hemei Chen, Chunhui Deng
Zeolitic imidazolate frameworks (ZIFs) are composed of tetrahedral transition metal ions and imidazolate type organic linkers. This kind of metal organic frameworks (MOFs) combines the unique properties of both zeolites and MOFs. Furthermore, ZIFs can be assembled under mild biocompatible conditions. These advantages make them be primarily studied for biochemical analysis. In this work, polydopamine-modified hydrophilic magnetic ZIFs were synthesized in a simple and mild way for the efficient extraction of low-abundance peptides...
May 15, 2017: Talanta
https://www.readbyqxmd.com/read/28340620/stable-high-level-expression-of-factor-viii-in-chinese-hamster-ovary-cells-in-improved-elongation-factor-1-alpha-based-system
#19
Nadezhda A Orlova, Sergey V Kovnir, Alexandre G Gabibov, Ivan I Vorobiev
BACKGROUND: Recombinant factor VIII (FVIII), used for haemophilia A therapy, is one of the most challenging among the therapeutic proteins produced in heterologous expression systems. Deletion variant of FVIII, in which the entire domain B is replaced by a short linker peptide, was approved for medical use. Efficacy and safety of this FVIII deletion variant are similar to full-length FVIII preparations while the level of production in CHO cells is substantially higher. Typical levels of productivity for CHO cell lines producing deletion variant FVIII-BDD SQ, described elsewhere, are 0...
March 24, 2017: BMC Biotechnology
https://www.readbyqxmd.com/read/28340537/study-on-a-3d-hydrogel-based-culture-model-for-characterizing-growth-of-fibroblasts-under-viral-infection-and-drug-treatment
#20
Xiaolu Zhu, Xianting Ding
Three-dimensional (3D) in vitro tissue models provide an approach for the systematic, repetitive, and quantitative study of drugs. In this study, we constructed an in vitro 3D acrylated hyaluronic acid (AHA) hydrogel model encapsulating fibroblasts, performed long-period 3D culture, and tested cellular topological changes and proliferation variation in the presence of herpes simplex virus-1 (HSV-1) as an infecting virus and acyclovir (ACV) as the treatment drug. The AHA hydrogels were formed by using Michael addition chemistry of bis-cysteine containing MMP-degradable cross-linker onto AHA prefunctionalized with cell adhesion peptides (RGD)...
March 1, 2017: SLAS Discov
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