Water soluble complexes of methyl β-cyclodextrin and sulconazole nitrate

Complexation between methyl β-cyclodextrin (Me βCD) and sulconazole nitrate (SULC) was realized both under freeze drying and ultrasonication conditions. The process was carried out in solution and in solid state. In solution, the complexation was evaluated using solubility studies, nuclear magnetic resonance spectroscopy (¹H-NMR) and UV–Vis absorption studies. In the solid state, differential scanning calorimetry (DSC), and X-ray diffraction studies were used. Solubility studies indicate the existence of inclusion complexes between SULC and Me βCD. ¹H-NMR data showed that the inclusion complexes have different structures, according with the method we used for synthesis: for the freeze dried method the complex is obtained by complexation of dichlorobenzene ring of SULC into inner cavity of CD while for ultrasonication method the complex is obtained by complexation of imidazole graph of SULC into the CD molecule. DSC and X-ray studies bring supplementary information concerning the formation of complex Me βCD–SULC. As a result of the inclusion process into Me βCD, the solubility of SULC increase significant, being 10 times more comparative with the pure drug. We anticipate that these modifications will have a significant impact on the biological effects of the drug, making the SULC–Me βCD complex an appropriate candidate for a new drug delivery system.     

Chromatographic Determination of Total Selenium in Biofortified Allium sp. following Piazselenol Formation and Micro-Solid-Phase Extraction

Herein, a method based on selective piazselenol formation is applied for total selenium determination in biofortified Allium species. Piazselenol is formed by reacting Se(IV) with an aromatic diamine, namely 4-nitro-1,2-phenylenediamine, in acidic medium. Samples were digested in a nitric acid/hydrogen peroxide open system, followed by selenate reduction in hydrochloric acid. Reaction conditions were optimized in terms of pH, temperature, reaction time, and other auxiliary reagents for interference removal, namely, EDTA and hydroxylamine. For the extraction of the selectively formed 4-nitro-piazselenol, micro-solid-phase extraction (μSPE) was applied, and the analysis and detection of the corresponding complex was performed by HPLC coupled with DAD. An external standard calibration curve was developed (R² = 0.9994) with good sensitivity, and was used to calculate the total selenium content from several Allium plants material, with good intermediate precision (RSD% < 16%). The accuracy of the method was evaluated using both, a comparison with an accepted reference method from our previously published data, as well as three certified reference material with recoveries between 84–126%. The limit of detection was determined to be 0.35 μg/g (in solids) and 1.1 μg/L (in solution), while the limit of quantification was 1.07 μg/g and 3.4 μg/L (in solution). Using the proposed method, selenium content can be quickly and accurately determined in several types of samples. In addition, this study present experimental conditions for overcoming the interferences that might be encountered in selenium determination using piazselenol.     

Cross‐linking of poly(methyl methacrylate) by oxozirconate and oxotitanate clusters

Radical polymerization of methyl methacrylate with 0.5‐2 mol% of the (meth)acrylate‐substituted oxozirconium and oxotitanium clusters Zr₆(OH)₄O₄(OMc)₁₂ (OMc = methacrylate), Zr₄O₂(OMc)₁₂, Ti₆O₄(OEt)₈(OMc)₈ and Ti₄O₂(OPrⁱ)₆(OAcr)₆ (OAcr = acrylate) results in an efficient cross‐linking of the organic polymers. The obtained inorganic‐organic hybrid polymers exhibit a higher thermal stability due to inhibited depolymerization reactions. Contrary to undoped poly(methyl methacrylate), the cluster cross‐linked polymers are insoluble but swell in organic solvents. The solvent uptake upon swelling decreases with an increasing amount of polymerized cluster. The impedance spectra of PMMA doped with various proportions of Zr₄O₂(OMc)₁₂ show that the capacitance of the polymers decreases with an increasing proportion of the cluster. The polymer doped with 2 mol% of Zr₄O₂(OMc)₁₂ shows an increase in conductivity to 0.9·10⁻⁷ S·cm⁻¹ at 74°C.     

Dispersion of discrete sample signals within aerosol spray chambers: preliminary investigations

A barrel-type spray chamber with a baffle system and various other structures were used for characterization of band-broadening phenomena occurring within aerosol spray chambers, with an ICP-AES detector used in this case. Absolute values of aerosol particle size distributions from nebulizer/spray chamber systems were measured and found to be affected by the relative positions of impact surfaces with respect to the nebulizer. Smaller particles, but less total mass was observed as the baffle was moved closer to the nebulizer tip. However, based on measurements herein, it does not appear that particle sizes in any case will be small enough within the spray chamber for diffusion to influence band broadening for the bulk of the aerosol mass, as particularly important for mass sensitive detectors such as ICP-AES, although diffusion is likely to be important to particle number sensitive detectors.

Dispersion within the turbulent gas-phase regions of spray chambers appears to be relatively small. Geometries which introduce stagnant gas flow regions appear to have larger effects on band-broadening. The smoke tests utilized in these studies were found to be useful aids for visualization of spray chamber flow phenomena that influence dispersion of discrete signals.

Recirculation phenomena can also play a role in band broadening. Recirculation of aerosol re-entrained into the nebulizer jet appears to have an effect on dispersion, as represented by the full width at half maximum values. On the other hand, recirculation renebulization leads to substantial peak tailing.     

Synthesis of silazanylene-vinylene oligomers via catalytic polycondensation of divinyltetramethyldisilazane

Ruthenium (e. g., RuHCl(CO)(PPh₃)₃ and [RuCl₂(CO)₃]₂) and rhodium complexes (e. g., [RhX(cod)]₂, where X = Cl, OSiMe₃) appear to be the first effective catalysts for polycondensation of divinyltetramethyldisilazane ( I ) (ADPOL) to give poly(silazanylene-vinylene)s. Ruthenium catalysts give oligomers (M_w = 2 380, M_w/M_n = 1.21) and a mixture of trans-tactic oligomers, respectively, while rhodium complexes lead to the formation of a mixture of cyclic and linear oligomers.     

Short-and long-range interaction parameters for polydimethylsiloxanes with different terminal groups

The paper discusses the behaviour of polydimethylsiloxanes with different terminal groups as induced by polymer molecular weight and solvent mixture composition in dilute solution.     

Preliminary Studies of Antimicrobial Activity of New Synthesized Hybrids of 2-Thiohydantoin and 2-Quinolone Derivatives Activated with Blue Light

Thiohydantoin and quinolone derivatives have attracted researchers’ attention because of a broad spectrum of their medical applications. The aim of our research was to synthesize and analyze the antimicrobial properties of novel 2-thiohydantoin and 2-quinolone derivatives. For this purpose, two series of hybrid compounds were synthesized. Both series consisted of 2-thiohydantoin core and 2-quinolone derivative ring, however one of them was enriched with an acetic acid group at N3 atom in 2-thiohydantoin core. Antibacterial properties of these compounds were examined against bacteria: Staphylococcus aureus, Bacillus subtilis, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae. The antimicrobial assay was carried out using a serial dilution method to obtain the MIC. The influence of blue light irradiation on the tested compounds was investigated. The relative yield of singlet oxygen (¹O₂*, ¹Δ_g) generation upon excitation with 420 nm was determined by a comparative method, employing perinaphthenone (PN) as a standard. Antimicrobial properties were also investigated after blue light irradiation of the suspensions of the hybrids and bacteria placed in microtitrate plates. Preliminary results confirmed that some of the hybrid compounds showed bacteriostatic activity to the reference Gram-positive bacterial strains and a few of them were bacteriostatic towards Gram-negative bacteria, as well. Blue light activation enhanced bacteriostatic effect of the tested compounds.