Search results for " modifica"
showing 10 items of 817 documents
Photo-Cross-Linked Hydrogels with Polysaccharide−Poly(amino acid) Structure: New Biomaterials for Pharmaceutical Applications
2006
The aim of this work has been the preparation and characterization of novel hydrogels with polysaccharide-poly(amino acid) structure having suitable physicochemical properties for pharmaceutical applications. In the first step, hyaluronic acid (HA) and alpha,beta-poly(N-2-hydroxyethyl)-DL-aspartamide (PHEA) have been derivatized with methacrylic anhydride (AMA), thus obtaining HA-AMA and PHM derivatives, respectively. In the second step, aqueous solutions of both these derivatives have been irradiated at 313 nm to obtain chemical hydrogels. The hydrogel obtained by irradiating for 15 min an aqueous solution containing 4% w/v of HA-AMA and 4% w/v of PHM resulted in the highest yield. Its swe…
Formation of a micropatterned titania photocatalyst by microcontact printed silicatein on gold surfaces
2012
The enzyme silicatein has been bioengineered to carry a thiol-bearing Au-affinity tag (Cys-tag) for direct immobilization on gold carriers in shortest time without the need for prior surface functionalization. Through microcontact printing, defined silicatein micropatterns were created on gold surfaces, facilitating the subsequent enzymatically controlled synthesis of photocatalytically active TiO(2).
A redox-sensitive nanofluidic diode based on nicotinamide-modified asymmetric nanopores
2017
[EN] We demonstrate a redox-sensitive nanofluidic diode whose ion rectification is modulated by the oxidation and reduction of chemical moieties incorporated on its surface. To achieve this goal, we have first synthesized the chemical compounds 1-(4-aminobutyl)-3-carbamoylpyridin-1-ium (Nic-BuNH2) and 3-carbamoyl-1-(2,4-dinitrophenyl)pyridinium (Nic-DNP). Then, the surface of track-etched single asymmetric nanopores is decorated with the redox-sensitive Nic-BuNH2 and Nic-DNP molecules using carbodiimide coupling chemistry and Zincke reaction, respectively. The success of the modification reactions is monitored through the changes in the current¿voltage (I¿V) curves prior to and after pore f…
Dynamic remodeling of histone modifications in response to osmotic stress in Saccharomyces cerevisiae.
2014
Abstract Background Specific histone modifications play important roles in chromatin functions; i.e., activation or repression of gene transcription. This participation must occur as a dynamic process. Nevertheless, most of the histone modification maps reported to date provide only static pictures that link certain modifications with active or silenced states. This study, however, focuses on the global histone modification variation that occurs in response to the transcriptional reprogramming produced by a physiological perturbation in yeast. Results We did a genome-wide chromatin immunoprecipitation analysis for eight specific histone modifications before and after saline stress. The most…
Transformation of Campylobacter jejuni
2000
Campylobacter jejuni is a Gram-negative bacterium and is a commensal of many animal species (Skirrow and Blaser, 1992). In humans it is the major cause of human bacterial enteritis both in developed and developing countries (Tauxe, 1992; Taylor, 1992). Many cases of Campylobacter enteritis in humans have been associated with the consumption of or contact with undercooked chicken meat (Deming et al., 1987; Harris et al., 1986).
Approaches for the introduction of fluorinated substituents into [1,2,3]Triazolo[1,5-a]pyridines
2014
Abstract [1,2,3]Triazolo[1,5-a]pyridines functionalization with a trifluoromethyl group has been achieved for the first time using different synthetic strategies. Furthermore, these scaffolds have been employed as starting material in the synthesis of new 2,6-disubstituted pyridines containing the trifluoromethyl group, compounds that are not available using other methodologies. A fluorine-mediated triazolopyridine dimerisation is described, improving the previously known synthetic method. Preliminary studies focused on exploring triazolopyridines reactivity with electrophilic fluorine have revealed a new approach for the obtainment of imidazopyridines.
New nitrene functionalizations onto sidewalls of carbon nanotubes and their spectroscopic analysis
2010
Abstract The reactivity of p -toluenesulfonyl, methylsulfonyl and trimethylsilyl nitrene, derived from the corresponding azides, was studied towards single-walled carbon nanotubes (SWCNT) prepared by electric arc or HiPCO (High-pressure CO conversion) methods. The functionalized SWCNTs were analyzed by Raman, IR, and VIS/NIR spectroscopy. The spectroscopic results indicated that covalent modification of the SWCNTs was successful. While the IR measurements gave evidence of successful reaction in all studied cases, the Raman measurements indicated differences in the reactivity of the two tube types and between different nitrenes. VIS/NIR spectrum was measured for reaction with p -toluenesulfo…
Efficient two-step synthesis of water soluble BODIPY–TREN chemosensors for copper(II) ions
2017
Two simple fluorescent sensors for Cu(II) ions were synthesized in two reaction steps, using recently developed C–H functionalization reactions for boron dipyrrins, starting from a standard 8-aryl-BODIPY dye and a tris(2-aminoethyl)amine (TREN) ligand. At pH 5, the resulting BODIPY–TREN conjugates are demonstrated to be promising, highly selective, water soluble, Cu(II) sensors that can permeate the cell membrane. crosscheck: This document is CrossCheck deposited related_data: Supplementary Information identifier: Bram Verbelen (ORCID) identifier: Wim Dehaen (ORCID) copyright_licence: The Royal Society of Chemistry has an exclusive publication licence for this journal copyright_licence: Thi…
The functionalization of nanodiamonds (diamondoids) as a key parameter of their easily controlled self-assembly in micro- and nanocrystals from the v…
2014
We detail herein readily accessible processes to control previously unobserved robust self-assemblies of nanodiamonds (diamondoids) in micro- and nanocrystals from their mild vapor deposition. The chemical functionalization of uniform and discernible nanodiamonds was found to be a key parameter, and depending on the type of functional group (hydroxy, fluorine, etc.) and its position on the diamondoid, the structure of the discrete deposits can vary dramatically. Thus, well-defined anisotropic structures such as rod, needle, triangle or truncated octahedron shapes can be obtained, and self-assembled edifices of sizes ranging from 20 nm to several hundred micrometers formed with conservation …
NMR structure of a non-conjugatable, ADP-ribosylation associated, ubiquitin-like domain from Tetrahymena thermophila polyubiquitin locus.
2019
Abstract Background Ubiquitin-like domains (UbLs), in addition to being post-translationally conjugated to the target through the E1-E2-E3 enzymatic cascade, can be translated as a part of the protein they ought to regulate. As integral UbLs coexist with the rest of the protein, their structural properties can differ from canonical ubiquitin, depending on the protein context and how they interact with it. In this work, we investigate T.th-ubl5, a UbL present in a polyubiquitin locus of Tetrahymena thermophila, which is integral to an ADP-ribosyl transferase protein. Only one other co-occurrence of these two domains within the same protein has been reported. Methods NMR, multiple sequence al…