Hydrophobic Chitosan Nanoparticles Loaded with Carvacrol against Pseudomonas aeruginosa Biofilms

Pseudomonas aeruginosa infections have become more challenging to treat and eradicate due to their ability to form biofilms. This study aimed to produce hydrophobic nanoparticles by grafting 11-carbon and three-carbon alkyl chains to a chitosan polymer as a platform to carry and deliver carvacrol for improving its antibacterial and antibiofilm properties. Carvacrol–chitosan nanoparticles showed ζ potential values of 10.5–14.4 mV, a size of 140.3–166.6 nm, and an encapsulation efficiency of 25.1–68.8%. Hydrophobic nanoparticles reduced 46–53% of the biomass and viable cells (7–25%) within P. aeruginosa biofilms. Diffusion of nanoparticles through the bacterial biofilm showed a higher penetration of nanoparticles created with 11-carbon chain chitosan than those formulated with unmodified chitosan. The interaction of nanoparticles with a 50:50 w/w phospholipid mixture at the air–water interface was studied, and values suggested that viscoelasticity and fluidity properties were modified. The modified nanoparticles significantly reduced viable P. aeruginosa in biofilms (0.078–2.0 log CFU·cm⁻²) and swarming motility (40–60%). Furthermore, the formulated nanoparticles reduced the quorum sensing in Chromobacterium violaceum. This study revealed that modifying the chitosan polarity to synthesize more hydrophobic nanoparticles could be an effective treatment against P. aeruginosa biofilms to decrease its virulence and pathogenicity, mainly by increasing their ability to interact with the membrane phospholipids and penetrate preformed biofilms.     

Elemental 2D imaging of paintings with a mobile EDXRF system

Imaging techniques are now used commonly and intensively in cultural heritage object analysis. Nowadays, many different techniques in nature as well as many applications exist, where they can be applied. X-ray radiography and infrared reflectography as well as UV photography are some of the most applied techniques. The study of works of art usually requires these techniques to be non-invasive. Furthermore, they are frequently required to perform in situ analysis. A few years ago, our laboratory developed a mobile energy-dispersive X-ray fluorescence and UV–vis–NIR coupled spectrometer, especially designed for fieldwork studies, where all three techniques can be applied strictly at the same site of analysis. Recent developments on a new positioning system have now allowed us to perform 2D elemental mappings with our equipment, which is especially well adapted to painting analysis. The system control is carried out entirely through a laptop computer running a dedicated homemade software. The positioning is achieved by means of a CCD camera embedded in the system and controlled via a Wi-Fi connection through the computer. The data acquisition system, which is made through a homemade multichannel pulse height analyzer, being also managed via the software mentioned above, goes through an Ethernet connection. We will present here the new developments of the system and an example of in situ 2D elemental mapping applied on an anonymous oil painting on wood panel. The discovery of a hidden painting under this oil painting makes it a good choice for a first example of 2D large scan with a mobile instrument.     

Measurement of ceftazidime concentration in human plasma by ultra‐performance liquid chromatography–tandem mass spectrometry. Application to critically ill patients and patients with osteoarticular infections

Ceftazidime is an antibiotic belonging to the third generation of the cephalosporin family. It is indicated in the treatment of serious, simple or mixed bacterial infections, and its administration in continuous or intermittent infusion allows optimization of the concentration of antibiotic to keep it above the minimum inhibitory concentration. We developed and validated a chromatographic method by ultra‐performance liquid chromatography–tandem mass spectrometry to measure ceftazidime concentration in human plasma. Following extraction with acetonitrile and 1,2‐dichloroethane, the chromatographic separation was achieved using an Acquity ® UPLC ® BEH^TM (2.1 × 100 mm i.d., 1.7 µm) reverse‐phase C₁₈ column, with a water–acetonitrile linear gradient containing 0.1% formic acid at a 0.4 mL/min flow rate. Ceftazidime and its internal standard (cefotaxime) were detected by electrospray ionization mass spectrometry in positive ion multiple reaction monitoring mode using mass‐to‐charge transitions of 547.0 → 467.9/396.1 and 456.0 → 395.8/324.1, respectively. The limit of quantification was 0.58 mg/L and linearity was observed in the range 0.58–160 mg/L. Coefficients of variation and absolute relative biases were <9.8 and 8.4%. The mean recovery for ceftazidime was 74.4 ± 8.1%. Evaluation of the matrix effect showed ion enhancement, and no carry‐over was observed. The validated method could be applied to daily clinical laboratory practice to measure the concentration of ceftazidime in plasma. Copyright © 2015 John Wiley & Sons, Ltd.     

Development and evaluation of a plastic scintillating resin for radioactive tin determination

Journal of Radioanalytical and Nuclear Chemistry - In the next few years, a large number of nuclear facilities will be closed. This will involve the measurement of large amounts of nuclear wastes...     

Experimental and theoretical structural study of 2,9-bis-(4-fluorophenyl)-azaadamantan-4-one ethylene ketal

The title ethylene ketal 1, C₂₃H₂₃F₂NO₂, has a tricyclic azaadamantane cage with aryl rings (4-fluorophenyl) substituted at the 2 and 9 positions. Rings A (C11-C16) and B (C17-C22) are attached to atoms C2 and C9 in axial and equatorial positions, respectively; and the presence of the five-membered 1,3-dioxolane ring attached to atom C4. The structural analysis of the title was carried out by experimental (single crystal X-ray diffraction and NMR) and confirmed by theoretical calculations (ab initio RHF, DFT and NMR-DFT-GIAO).     

Reducing activity of polyphenols with stable radicals of the TTM series. Electron transfer versus H-abstraction reactions in flavan-3-ols

A new method to test the antioxidant activity of polyphenols by electron transfer reactions to a stable organic free radical, tris(2,4,6-trichloro-3,5-dinitrophenyl)methyl radical (HNTTM), is reported. Therefore, the activity of the natural flavanols, (-)-epicatechin, and two synthetic derivatives, 4beta-(S-cysteinyl)epicatechin and 4beta-(2-aminoethylthio)epicatechin, can be differentiated by their capacity to transfer hydrogen atoms to 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) and to transfer electrons to HNTTM. [structure: see text]     

Chemoselective radical cleavage of Cbz-protected nitrogen compounds

[reaction: see text] Tributylstannyl radicals promote the deprotection of N-Cbz derivatives of amides and nitrogen-containing heteroaromatic rings. These radical conditions do not affect N-Cbz derivatives of basic amines.     

Ruthenium(III) chloride complex with a tridentate bis(arylimino)pyridine ligand: synthesis, spectra, X-ray structure, 9-ethylguanine binding pattern, and in vitro cytotoxicity

The synthetic, spectroscopic, structural, and biological studies of a bis(arylimino)pyridine Ru(III) chloride compound containing the ligand, 2,6-bis(2,4,6-trimethylphenyliminomethyl)pyridine are reported. The bis(arylimino)pyridine ligand, with three donor nitrogen atoms, was synthesized by condensation of 2,6-pyridinedicarboxaldehyde with 2,4,6-trimethylaniline. The Ru(III) complex, with formula [RuCl 3(L1)](H 2O) (RuL1), where L1 = 2,6-bis(2,4,6-trimethylphenyliminomethyl)pyridine, was structurally determined on the basis of analytical and spectroscopic (IR, UV-vis, ESI-MS) studies. A straightforward strategy to fully characterize the paramagnetic compound using advanced (1)H NMR is reported. This new complex is a prototype for a series of new anticancer Ru(III) and Ru(II) compounds with improved cytostatic properties; likely to be modified in a desirable manner due to the relatively facile ligand modification of the bis(imino)pyridines and their molecular architecture. The present Ru(III) complex is the first example of this family of Ru(III)/Ru(II) anticancer compounds with the aimed physicochemical characteristics. Although the ligand itself is moderately active in selected cell lines (EVSA-T and MCF-7), the activity of the [Ru(L1)Cl 3] complex has increased significantly for a broad range of cancer cell lines tested in vitro (IC 50 values = 11 approximately 17 microM). Reaction of the RuL1 species with the DNA model base 9-ethylguanine (9EtGua) was found to produce in a redox reaction the species trans-[Ru(II)(L1)(9EtGua) 2(H 2O)](ClO 4) 2 (abbreviated as RuL1-9EtGua), which was studied in solution and also in the solid state, by X-ray crystallography. The structure comprises the as yet unknown trans-bis(purine)Ru(II) unit.     

Additive Tuning of Redox Potential in Metallacarboranes by Sequential Halogen Substitution

The first artificially made set of electron acceptors is presented that are derived from a unique platform Cs[3,3′‐Co(C₂B₉H₁₁)₂], for which the redox potential of each differs from its predecessor by a fixed amount. The sequence of electron acceptors is made by substituting one, two, or more hydrogen atoms by chlorine atoms, yielding Cs[3,3′‐Co(C₂B₉H_11?yCl_y)(C₂B₉H_11?zCl_z)]. The higher the number of chlorine substituents, the more prone the platform is to be reduced. The effect is completely additive, so if a single substitution implies a reduction of 0.1 V of the redox potential of the parent complex, then ten substitutions imply a reduction of 1 V.     

Simultaneous Measurement of Cyclosporine A,Everolimus, Sirolimus and Tacrolimus Concentrations in Human Blood by UPLC–MS/MS

Liquid chromatography coupled with tandem mass spectrometry for therapeutic drug monitoring of immunosuppressants has been widely adopted in clinical chemistry laboratories. However, UPLC is replacing classical LC techniques, providing higher resolution and speed. We developed and validated an UPLC–MS/MS method for the simultaneous measurement of cyclosporine A, everolimus, sirolimus and tacrolimus concentrations in human blood. Following extraction with a zinc sulfate solution and acetonitrile, the chromatographic separation was achieved using an Acquity^® UPLC^® BEH™ (2.1 × 30 mm id, 1.7 µm) reverse-phase C₁₈ column, with a water/methanol linear gradient containing 2 mM ammonium acetate with 0.1 % formic acid at a 0.5 mL min⁻¹ flow rate. All immunosuppressants were detected by ESI mass spectrometry in positive ion multiple reaction monitoring mode using mass-to-charge transitions of 1219.8 → 1202.6/1184.4, 975.5 → 908.3/891.6, 931.5 → 864.3/883.3, 821.4 → 768.2/719.9 for cyclosporine A, everolimus, sirolimus and tacrolimus, respectively. Coefficients of variation and relative bias were less than 5.8 and 9.7 % for cyclosporine A, 8.7 and 6.4 % for everolimus, 8.5 and 7.2 % for sirolimus and 6.7 and 4.7 % for tacrolimus. Limits of quantification were 15.4 µg L⁻¹ for cyclosporine A, 1.42 µg L⁻¹ for everolimus, 1.58 µg L⁻¹ for sirolimus and 0.65 µg L⁻¹ for tacrolimus. Mean recoveries were greater than 77.6 % for all immunosuppressants. Evaluation of the matrix effect showed ion suppression for all the immunosuppressants, except for cyclosporine A, which suffered ion enhancement. No carry-over was observed. The validated method appears to be well adapted for therapeutic drug monitoring of multiple immunosuppressants in daily clinical practice.