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ACS Omega

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https://www.readbyqxmd.com/read/29732454/chemically-treated-3d-printed-polymer-scaffolds-for-biomineral-formation
#1
Richard J Jackson, P Stephen Patrick, Kristopher Page, Michael J Powell, Mark F Lythgoe, Mark A Miodownik, Ivan P Parkin, Claire J Carmalt, Tammy L Kalber, Joseph C Bear
We present the synthesis of nylon-12 scaffolds by 3D printing and demonstrate their versatility as matrices for cell growth, differentiation, and biomineral formation. We demonstrate that the porous nature of the printed parts makes them ideal for the direct incorporation of preformed nanomaterials or material precursors, leading to nanocomposites with very different properties and environments for cell growth. Additives such as those derived from sources such as tetraethyl orthosilicate applied at a low temperature promote successful cell growth, due partly to the high surface area of the porous matrix...
April 30, 2018: ACS Omega
https://www.readbyqxmd.com/read/29732453/pyrimidine-nucleosides-with-a-reactive-%C3%AE-chlorovinyl-sulfone-or-%C3%AE-keto-sulfone-group-at-the-c5-position-their-reactions-with-nucleophiles-and-electrophiles-and-their-polymerase-catalyzed-incorporation-into-dna
#2
Sazzad H Suzol, A Hasan Howlader, Zhiwei Wen, Yaou Ren, Eduardo E Laverde, Carol Garcia, Yuan Liu, Stanislaw F Wnuk
Transition-metal-catalyzed chlorosulfonylation of 5-ethynylpyrimidine nucleosides provided ( E )-5-(β-chlorovinyl)sulfones A , which undergo nucleophilic substitution with amines or thiols affording B . The treatment of vinyl sulfones A with ammonia followed by acid-catalyzed hydrolysis of the intermediary β-sulfonylvinylamines gave 5-(β-keto)sulfones C . The latter reacts with electrophiles, yielding α-carbon-alkylated or -sulfanylated analogues D . The 5'-triphosphates of A and C were incorporated into double-stranded DNA, using open and one-nucleotide gap substrates, by human or Escherichia coli DNA-polymerase-catalyzed reactions...
April 30, 2018: ACS Omega
https://www.readbyqxmd.com/read/29732452/katg-mediated-oxidation-leading-to-reduced-susceptibility-of-bacteria-to-kanamycin
#3
Peter C Loewen, P Malaka De Silva, Lynda J Donald, Jacek Switala, Jacylyn Villanueva, Ignacio Fita, Ayush Kumar
Resistance to antibiotics has become a serious problem for society, and there are increasing efforts to understand the reasons for and sources of resistance. Bacterial-encoded enzymes and transport systems, both innate and acquired, are the most frequent culprits for the development of resistance, although in Mycobacterium tuberculosis , the catalase-peroxidase, KatG, has been linked to the activation of the antitubercular drug isoniazid. While investigating a possible link between aminoglycoside antibiotics and the induction of oxidative bursts, we observed that KatG reduces susceptibility to aminoglycosides...
April 30, 2018: ACS Omega
https://www.readbyqxmd.com/read/29732451/gold-i-complexes-of-the-geminal-phosphinoborane-t-bu-2-pch-2-bph-2
#4
Devin H A Boom, Andreas W Ehlers, Martin Nieger, Marc Devillard, Ghenwa Bouhadir, Didier Bourissou, J Chris Slootweg
In this work, we explored the coordination properties of the geminal phosphinoborane t Bu2 PCH2 BPh2 ( 2 ) toward different gold(I) precursors. The reaction of 2 with an equimolar amount of the sulfur-based complex (Me2 S)AuCl resulted in displacement of the SMe2 ligand and formation of linear phosphine gold(I) chloride 3 . Using an excess of ligand 2 , bisligated complex 4 was formed and showed dynamic behavior at room temperature. Changing the gold(I) metal precursor to the phosphorus-based complex, (Ph3 P)AuCl impacted the coordination behavior of ligand 2 ...
April 30, 2018: ACS Omega
https://www.readbyqxmd.com/read/29732450/mutations-alter-rna-mediated-conversion-of-human-prions
#5
Erik J Alred, Izra Lodangco, Jennifer Gallaher, Ulrich H E Hansmann
Prion diseases are connected with self-replication and self-propagation of misfolded proteins. The rate-limiting factor is the formation of the initial seed. We have recently studied the early stages in the conversion between functional PrPC and the infectious scrapie PrPSC form, triggered by the binding of RNA. Here, we study how this process is modulated by the prion sequence. We focus on residues 129 and 178, which are connected to the hereditary neurodegenerative disease fatal familial insomnia.
April 30, 2018: ACS Omega
https://www.readbyqxmd.com/read/29732449/integration-of-magnetic-bead-based-cell-selection-into-complex-isolations
#6
Hannah M Pezzi, David J Niles, Jennifer L Schehr, David J Beebe, Joshua M Lang
Magnetic bead-based analyte capture has emerged as a ubiquitous method in cell isolation, enabling the highly specific capture of target populations through simple magnetic manipulation. To date, no "one-size fits all" magnetic bead has been widely adopted leading to an overwhelming number of commercial beads. Ultimately, the ideal bead is one that not only facilitates cell isolation but also proves compatible with the widest range of downstream applications and analytic endpoints. Despite the diverse offering of sizes, coatings, and conjugation chemistries, few studies exist to benchmark the performance characteristics of different commercially available beads; importantly, these bead characteristics ultimately determine the ability of a bead to integrate into the user's assay...
April 30, 2018: ACS Omega
https://www.readbyqxmd.com/read/29732448/a-new-synthesis-approach-for-carbon-nitrides-poly-triazine-imide-and-its-photocatalytic-properties
#7
Leonard Heymann, Björn Schiller, Heshmat Noei, Andreas Stierle, Christian Klinke
Poly(triazine imide) (PTI) is a material belonging to the group of carbon nitrides and has shown to have competitive properties compared to melon or g-C3 N4 , especially in photocatalysis. As most of the carbon nitrides, PTI is usually synthesized by thermal or hydrothermal approaches. We present and discuss an alternative synthesis for PTI which exhibits a pH-dependent solubility in aqueous solutions. This synthesis is based on the formation of radicals during electrolysis of an aqueous melamine solution, coupling of resulting melamine radicals and the final formation of PTI...
April 30, 2018: ACS Omega
https://www.readbyqxmd.com/read/29732447/high-resolution-adhesion-kinetics-of-egcg-exposed-tumor-cells-on-biomimetic-interfaces-comparative-monitoring-of-cell-viability-using-label-free-biosensor-and-classic-end-point-assays
#8
Beatrix Peter, Rita Ungai-Salanki, Bálint Szabó, Agoston G Nagy, Inna Szekacs, Szilvia Bősze, Robert Horvath
A high-throughput label-free resonant waveguide grating biosensor, the Epic BenchTop, was utilized to in situ monitor the adhesion process of cancer cells on Arg-Gly-Asp tripeptide displaying biomimetic polymer surfaces. Using highly adherent human cervical adenocarcinoma (HeLa) cells as a model system, cell adhesion kinetic data with outstanding temporal resolution were obtained. We found that pre-exposing the cells to various concentrations of the main extract of green tea, the (-)-epigallocatechin gallate (EGCG), largely affected the temporal evolution of the adhesion process...
April 30, 2018: ACS Omega
https://www.readbyqxmd.com/read/29732446/design-synthesis-and-biological-evaluations-of-asymmetric-bow-tie-pamam-dendrimer-based-conjugates-for-tumor-targeted-drug-delivery
#9
Tao Wang, Yaozhong Zhang, Longfei Wei, Yuhan G Teng, Tadashi Honda, Iwao Ojima
A unique asymmetric bow-tie poly(amidoamine) (PAMAM) dendrimer (ABTD) scaffold was designed and developed as a well-defined macromolecular carrier for tumor-targeted drug delivery. The ABTD scaffold in this study consists of a G3-half-dendron (G3-HD) unit and a G1-half-dendron (G1-HD) unit, bearing thiol moiety in each unit and a bis(maleimide) linker unit, which undergo sequential thiol-maleimide coupling to assemble the scaffold. This assembly methodology is applicable to all other combinations of different generations of PAMAM dendrimers...
April 30, 2018: ACS Omega
https://www.readbyqxmd.com/read/29732445/radiation-therapy-combined-with-cowpea-mosaic-virus-nanoparticle-in-situ-vaccination-initiates-immune-mediated-tumor-regression
#10
Ravi Patel, Anna E Czapar, Steven Fiering, Nancy L Oleinick, Nicole F Steinmetz
Epithelial ovarian cancer is a deadly gynecologic malignancy because of its late detection, usually after local and distant metastatic spread. These cancers develop resistance to traditional chemotherapeutic agents; therefore, the development of next-generation immunotherapeutic approaches may have a significant promise in improving outcomes. A novel immunotherapeutic approach utilizing combination radiation therapy (RT) with immunostimulatory cowpea mosaic virus (CPMV) was tested in a preclinical syngeneic mouse model of ovarian carcinoma...
April 30, 2018: ACS Omega
https://www.readbyqxmd.com/read/29732444/rosettaligandensemble-a-small-molecule-ensemble-driven-docking-approach
#11
Darwin Yu Fu, Jens Meiler
RosettaLigand is a protein-small-molecule (ligand) docking software capable of predicting binding poses and is used for virtual screening of medium-sized ligand libraries. Structurally similar small molecules are generally found to bind in the same pose to one binding pocket, despite some prominent exceptions. To make use of this information, we have developed RosettaLigandEnsemble (RLE). RLE docks a superimposed ensemble of congeneric ligands simultaneously. The program determines a well-scoring overall pose for this superimposed ensemble before independently optimizing individual protein-small-molecule interfaces...
April 30, 2018: ACS Omega
https://www.readbyqxmd.com/read/29623305/dramatic-improvement-of-the-mechanical-strength-of-silane-modified-hydroxyapatite-gelatin-composites-via-processing-with-cosolvent
#12
Huamin Hu, Bo-Wen Huang, Yan-Ting Lee, Jun Hu, Sing-Wai Wong, Ching-Chang Ko, Wei You
Bone tissue engineering (BTE) requires a sturdy biomaterial for scaffolds for restoration of large bone defects. Ideally, the scaffold should have a mechanical strength comparable to the natural bone in the implanted site. We show that adding cosolvent during the processing of our previously developed composite of hydroxyapatite-gelatin with a silane cross-linker can significantly affect its mechanical strength. When processed with tetrahydrofuran (THF) as the cosolvent, the new hydroxyapatite-gelatin composite can demonstrate almost twice the compressive strength (97 vs 195 MPa) and biaxial flexural strength (222 vs 431 MPa) of the previously developed hydroxyapatite-gelatin composite (i...
March 31, 2018: ACS Omega
https://www.readbyqxmd.com/read/29623304/toward-understanding-drug-incorporation-and-delivery-from-biocompatible-metal-organic-frameworks-in-view-of-cutaneous-administration
#13
Sara Rojas, Isabel Colinet, Denise Cunha, Tania Hidalgo, Fabrice Salles, Christian Serre, Nathalie Guillou, Patricia Horcajada
Although metal-organic frameworks (MOFs) have widely demonstrated their convenient performances as drug-delivery systems, there is still work to do to fully understand the drug incorporation/delivery processes from these materials. In this work, a combined experimental and computational investigation of the main structural and physicochemical parameters driving drug adsorption/desorption kinetics was carried out. Two model drugs (aspirin and ibuprofen) and three water-stable, biocompatible MOFs (MIL-100(Fe), UiO-66(Zr), and MIL-127(Fe)) have been selected to obtain a variety of drug-matrix couples with different structural and physicochemical characteristics...
March 31, 2018: ACS Omega
https://www.readbyqxmd.com/read/29623303/bis-arylimidazole-iridium-picolinate-emitters-and-preferential-dipole-orientation-in-films
#14
Aron J Huckaba, Alessia Senes, Sadig Aghazada, Azin Babaei, Stefan C J Meskers, Iwan Zimmermann, Pascal Schouwink, Natalia Gasilova, René A J Janssen, Henk J Bolink, Mohammad Khaja Nazeeruddin
The straightforward synthesis and photophysical properties of a new series of heteroleptic iridium(III) bis(2-arylimidazole) picolinate complexes are reported. Each complex has been characterized by nuclear magnetic resonance, UV-vis, cyclic voltammetry, and photoluminescent angle dependency, and the emissive properties of each are described. The preferred orientation of transition dipoles in emitter/host thin films indicated more preferred orientation than homoleptic complex Ir(ppy)3 .
March 31, 2018: ACS Omega
https://www.readbyqxmd.com/read/29623302/novel-fully-organic-water-oxidation-electrocatalysts-a-quest-for-simplicity
#15
Yanlin Wu, Volker Klein, Manuela S Killian, Christopher Behling, Sany Chea, Svetlana B Tsogoeva, Julien Bachmann
Despite the growing need for readily available and inexpensive catalysts for the half-reactions involved in water splitting, water oxidation and reduction electrocatalysts are still traditionally based on noble metals. One long-standing challenge has been the development of an oxygen evolution reaction catalyzed by easily available, structurally simple, and purely organic compounds. Herein, we first generalize the performance of the known N -ethyl-flavinium ion to a number of derivatives. Furthermore, we demonstrate an unprecedented application of different pyridinium and related salts as very simple, inexpensive water oxidation organocatalysts consisting of earth-abundant elements (C, H, O, and N) exclusively...
March 31, 2018: ACS Omega
https://www.readbyqxmd.com/read/29623301/peptide-based-bioinspired-approach-to-regrowing-multilayered-aprismatic-enamel
#16
Kaushik Mukherjee, Qichao Ruan, Steven Nutt, Jinhui Tao, James J De Yoreo, Janet Moradian-Oldak
The gradual discovery of functional domains in native enamel matrix proteins has enabled the design of smart bioinspired peptides for tooth enamel mimetics and repair. In this study, we expanded upon the concept of biomineralization to design smaller amelogenin-inspired peptides with conserved functional domains for clinical translation. The synthetic peptides displayed a characteristic nanostructured scaffold reminiscent of 'nanospheres' seen in the enamel matrix and effectively controlled apatite nucleation in vitro resulting in the formation of smaller crystallites...
March 31, 2018: ACS Omega
https://www.readbyqxmd.com/read/29600290/reorientation-of-the-methyl-group-in-mas-iii-is-the-rate-limiting-step-in-the-arsm-as-iii-s-adenosylmethionine-methyltransferase-reaction
#17
Charles Packianathan, Jiaojiao Li, Palani Kandavelu, Banumathi Sankaran, Barry P Rosen
The most common biotransformation of trivalent inorganic arsenic (As(III)) is methylation to mono-, di-, and trimethylated species. Methylation is catalyzed by As(III) S -adenosylmethionine (SAM) methyltransferase (termed ArsM in microbes and AS3MT in animals). Methylarsenite (MAs(III)) is both the product of the first methylation step and the substrate of the second methylation step. When the rate of the overall methylation reaction was determined with As(III) as the substrate, the first methylation step was rapid, whereas the second methylation step was slow...
March 2018: ACS Omega
https://www.readbyqxmd.com/read/29619413/mutational-analysis-of-neuropeptide-y-reveals-unusual-thermal-stability-linked-to-higher-order-self-association
#18
Stephen Quirk, Mandi M Hopkins, Hailey Bureau, Ryan J Lusk, Caley Allen, Rigoberto Hernandez, David L Bain
Neuropeptide Y (NPY) is a 36-residue peptide, abundant in the central and peripheral nervous system. The peptide interacts with membrane-bound receptors to control processes such as food intake, vasoconstriction, and memory retention. The N-terminal polyproline sequence of NPY folds back onto a C-terminal α-helix to form a hairpin structure. The hairpin undergoes transient unfolding to allow the monomer to interact with its target membranes and receptors and to form reversible dimers in solution. Using computational, functional, and biophysical approaches, we characterized the role of two conserved tyrosines (Y20 and Y27) located within the hydrophobic core of the hairpin fold...
February 28, 2018: ACS Omega
https://www.readbyqxmd.com/read/29503976/role-of-polymorphism-and-thin-film-morphology-in-organic-semiconductors-processed-by-solution-shearing
#19
REVIEW
Sergi Riera-Galindo, Adrián Tamayo, Marta Mas-Torrent
Organic semiconductors (OSCs) are promising materials for cost-effective production of electronic devices because they can be processed from solution employing high-throughput techniques. However, small-molecule OSCs are prone to structural modifications because of the presence of weak van der Waals intermolecular interactions. Hence, controlling the crystallization in these materials is pivotal to achieve high device reproducibility. In this perspective article, we focus on controlling polymorphism and morphology in small-molecule organic semiconducting thin films deposited by solution-shearing techniques compatible with roll-to-roll systems...
February 28, 2018: ACS Omega
https://www.readbyqxmd.com/read/29503975/manipulation-of-the-geometry-and-modulation-of-the-optical-response-of-surfactant-free-gold-nanostars-a-systematic-bottom-up-synthesis
#20
Agampodi S De Silva Indrasekara, Sean F Johnson, Ren A Odion, Tuan Vo-Dinh
Among plasmonic nanoparticles, surfactant-free branched gold nanoparticles have exhibited exceptional properties as a nanoplatform for a wide variety of applications ranging from surface-enhanced Raman scattering sensing and imaging applications to photothermal treatment and photoimmunotherapy for cancer treatments. The effectiveness and reliability of branched gold nanoparticles in biomedical applications strongly rely on the consistency and reproducibility of physical, chemical, optical, and therapeutic properties of nanoparticles, which are mainly governed by their morphological features...
February 28, 2018: ACS Omega
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