Search results for " Fourier Transform Infrared"
showing 10 items of 255 documents
Revisiting the thiosemicarbazonecopper(II) reaction with glutathione. Activity against colorectal carcinoma cell lines.
2018
Thiosemicarbazones (TSCs), and their copper derivatives, have been extensively studied mainly due to the potential applications as antitumor compounds. A part of the biological activity of the TSC-CuII complexes rests on their reactivity against cell reductants, as glutathione (GSH). The present paper describes the structure of the [Cu(PTSC)(ONO2)]n compound (1) (HPTSC =pyridine-2-carbaldehyde thiosemicarbazone) and its spectroscopic and magnetic properties. ESI studies performed on the reaction of GSH with 1 and the analogous [{Cu (PTSC*)(ONO2)}2] derivative (2, HPTSC* =pyridine-2-carbaldehyde 4N-methylthiosemicarbazone) show the absence of peaks related with TSC-Cu-GSH species. However GS…
Cellulose‑copper as bio-supported recyclable catalyst for the clickable azide-alkyne [3 + 2] cycloaddition reaction in water.
2018
Abstract Naturally-occurring cellulose has been employed as a bio-support macromolecule for the immobilization of either copper(I) or copper(II) ions in order to click azide and alkyne derivatives in water. Under such a click regime, 1,4-disubstitued-1,2,3-triazoles were obtained regioselectively in excellent yields at room temperature. The reaction work-up is simple and the bio-heterogeneous catalyst that has been fully characterized by AAS, SEM, EDX and FT-IR can be easily separated and reused at least five times without any significant decrease in its activity and selectivity, particularly in the case of the very stable CuI-Cellulose.
Generic Method for Modular Surface Modification of Cellulosic Materials in Aqueous Medium by Sequential Click-Reaction and Adsorption
2012
A generic approach for heterogeneous surface modification of cellulosic materials in aqueous medium, applicable for a wide range of functionalizations, is presented. In the first step, carboxymethyl cellulose (CMC) modified with azide or alkyne functionality, was adsorbed on a cellulosic substrate, thus, providing reactive sites for azide–alkyne cycloaddition click reactions. In the second step, functional units with complementary click units were reacted on the cellulose surface, coated by the click-modified CMC. Selected model functionalizations on diverse cellulosic substrates are shown to demonstrate the generality of the approach. The concept by sequentially combining the robust physic…
Lactobacillus acidophilus La5 and Bifidobacterium lactis Bb12 cell surface hydrophobicity and survival of the cells under adverse environmental condi…
2012
Abstract Changes in the cell surface hydrophobicity (CSH) of probiotic bacteria Lactobacillus acidophilus La5 and Bifidobacterium lactis Bb12 and the survival of these cells were examined in response to varied cultivation conditions and adverse environmental conditions. An inverse linear relationship (P < 0.01) was detected between the CSH of intact L. acidophilus La5 and B. lactis Bb12 and survival of cells subjected to subsequent freezing/thawing, long-term storage or exposure to mineral and bile acids. The observed relationships were supported by significant correlations between the CSH and changes in composition of the cell envelopes (proteins, lipids and carbohydrates) of L. aci…
Film-forming process and biocide assessment of high-molecular-weight chitosan as determined by combined ATR-FTIR spectroscopy and antimicrobial assay…
2006
This pioneering study reported about the film-forming properties of high-molecular-weight chitosan as followed in situ by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, and has implications in fields such as biomedical, pharmaceutical, packaging, and coating applications. From the results, it was observed that immediately after dissolution in an acetic acid aqueous solution and subsequent casting over the ATR crystal, the formed carboxylate antimicrobial (-NH3+ -OOCH) species are not stable in the film formulation and become reduced over time; further assays confirmed previous research, which suggested that the presence and stability of these groups is stron…
Design, characterization and in vitro evaluation of 5-aminosalicylic acid loaded N-succinyl-chitosan microparticles for colon specific delivery
2011
The objective of this study was to prepare NS-chitosan microparticles for the delivery of 5-aminosalicylic acid (5-ASA) to the colon. Microparticles can spread out over a large area of colon allowing a more effective local efficacy of 5-ASA. N-Succinyl-chitosan was chosen as carrier system because of its excellent pharmaceutical properties in colon drug targeting such as poor solubility in acid environment, biocompatibility, mucoadhesive properties, and low toxicity. It was prepared by introducing succinic group into chitosan N-terminals of the glucosamine units. 5-ASA loaded NS-chitosan microparticles were prepared using spray-drying. As a control, a matrix obtained by freeze-drying techni…
Genesis of amorphous calcium carbonate containing alveolar plates in the ciliate Coleps hirtus (Ciliophora, Prostomatea).
2013
7 pages; International audience; In the protist world, the ciliate Coleps hirtus (phylum Ciliophora, class Prostomatea) synthesizes a peculiar biomineralized test made of alveolar plates, structures located within alveolar vesicles at the cell cortex. Alveolar plates are arranged by overlapping like an armor and they are thought to protect and/or stiffen the cell. Although their morphology is species-specific and of complex architecture, so far almost nothing is known about their genesis, their structure and their elemental and mineral composition. We investigated the genesis of new alveolar plates after cell division and examined cells and isolated alveolar plates by electron microscopy, e…
Climate variation during the Holocene influenced the skeletal properties of Chamelea gallina shells in the North Adriatic Sea (Italy)
2021
Understanding how marine taxa will respond to near-future climate changes is one of the main challenges for management of coastal ecosystem services. Ecological studies that investigate relationships between the environment and shell properties of commercially important marine species are commonly restricted to latitudinal gradients or small-scale laboratory experiments. This paper aimed to explore the variations in shell features and growth of the edible bivalve Chamelea gallina from the Holocene sedimentary succession to present-day thanatocoenosis of the Po Plain-Adriatic Sea system (Italy). Comparing the Holocene sub-fossil record to modern thanatocoenoses allowed obtaining an insight o…
Quantification of hydrolysis of toxic organophosphates and organophosphonates by diisopropyl fluorophosphatase from Loligo vulgaris by in situ Fourie…
2008
Abstract The enzyme diisopropyl fluorophosphatase (DFPase) from the squid Loligo vulgaris effectively catalyzes the hydrolysis of diisopropyl fluorophosphate (DFP) and a number of organophosphorus nerve agents, including sarin, soman, cyclosarin, and tabun. Up to now, the determination of kinetic data has been achieved by techniques such as pH-stat titration, ion-selective electrodes, and fluorogenic substrate analogs. We report a new assaying method using in situ Fourier transform infrared (FTIR) spectroscopy with attenuated total reflection (ATR) for the real-time determination of reaction rates. The method employs changes in the P–O–R stretching vibration of DFP and nerve agent substrate…
Synthesis, structural investigations on organotin(IV) chlorin-e6 complexes, their effect on sea urchin embryonic development and induced apoptosis
2004
Four new organotin(IV) chlorin derivatives, [chlorin=chlorin-e(6)=21H,23H-porphine-2-propanoic acid, 18-carboxy-20-(carboxymethyl)-8-ethenyl-13-ethyl-2,3-di-hydro-3,7,12,17-tetramethyl-(2S-trans)-], with formula (R(2)Sn)(3)(chlorin)(2).2H(2)O (R=Me, n-Bu) and (R(3)Sn)(3)chlorin.2H(2)O (R=Me, Ph) have been synthesized. The solid state and solution phase structures have been investigated by FT-IR, (119)Sn Mössbauer, (1)H and (13)C NMR spectroscopy. In the solid state, (R(2)Sn)(3)(chlorin)(2).2H(2)O complexes contain six coordinated Sn(IV), in a skew trapezoidal environment by forming trans-R(2)SnO(4) polymeric units. As far as (R(3)Sn)(3)chlorin.2H(2)O complexes are concerned, Sn(IV) is five …