Selective determination of doxorubicin and doxorubicinol in rat plasma by HPLC with photosensitization reaction followed by chemiluminescence detection

A highly sensitive and selective high-performance liquid chromatography (HPLC) method was developed for the determination of doxorubicin (DXR) and its metabolite doxorubicinol (DXR-ol) in rat plasma. The method was based on photosensitization reaction followed by peroxyoxalate chemiluminescence detection (PO-CL). DXR and DXR-ol that were fluorescent quinones, served as a photosensitizer in the presence of a hydrogen atom donor such as ethanol under aerobic conditions to produce hydrogen peroxide. Then the generated hydrogen peroxide and DXR or DXR-ol were monitored through PO-CL reaction by mixing with aryloxalate as a single post-column reagent that enabled highly selective and sensitive determination of DXR and DXR-ol. The separation of DXR and DXR-ol by HPLC was accomplished isocratically on an ODS column within 15 min. The method involves a simple one step protein precipitation by methanol and a sample size of 50-μL was sufficient. Besides, it can detect accurately the low plasma concentrations. The detection limits (signal-to-noise ratio = 3) were 4.5 and 3.8 fmol for DXR and DXR-ol, respectively. The percentage recovery was found to be 90.7-102.4% and the inter- and intra-assay RSD values in rat plasma were 2.5-8.9%. The method has been successfully used to study pharmacokinetic profiles of DXR and DXR-ol in rats after a single-dose of DXR.     

Experimental vapor pressures of 1,2-bis(dimethylamino)ethane, 1-methylmorpholine, 1,2-bis(2-aminoethoxy)ethane and N-benzylethanolamine between 273.18 and 364.97 K

In this work, the experimental vapor pressures of four amines 1,2-bis(dimethylamino)ethane, 1-methylmorpholine, 1,2-bis(2-aminoethoxy)ethane and N-benzylethanolamine using a static apparatus are reported. The temperature range is comprised between 273.18 and 364.97 K and the pressure range between 0.782 Pa and 333 kPa. The molar enthalpies of vaporization at 298.15 K were calculated from Clausius–Clapeyron equation fitted on the experimental results.     

Numerical investigation for peristaltic flow of Carreau–Yasuda magneto-nanofluid with modified Darcy and radiation

This paper reports numerical study for peristalsis of Carreau–Yasuda nanofluid in a symmetric channel. Constant magnetic field is applied. Modified Darcy’s law and nonlinear thermal radiation effects are considered. Viscous dissipation and Ohmic heating effects are also present. Long wavelength and small Reynolds number are considered. Resulting nonlinear problems are solved numerically. Graphical illustrations depict that temperature increases for larger Hartmann number and it decays for thermophoresis parameter.

     

In vitro selection and characterization of deoxyribonucleic acid aptamers for digoxin

The low therapeutic index of digoxin necessitates careful monitoring of its serum levels. Most of digoxin immunoassays suffer from interferences with digoxin-like immunoreactive substances. Since aptamers have been shown to be highly specific for their targets, the aim of this study was to develop DNA aptamers for this widely used cardiac glycoside. Digoxin was coated onto the surface of streptavidin magnetic beads. DNA aptamers against digoxin were designed using Systematic Evolution of Ligands by Exponential enrichment method (SELEX) by 11 iterative rounds of incubation of digoxin-coated streptavidin magnetic beads with synthetic DNA library, DNA elution, electrophoresis and PCR amplification. The PCR product was cloned and sequenced. Binding affinity was determined using digoxin–BSA conjugate, coated onto ELISA plate. Inhibitory effect of anti-digoxin aptamer was conducted using isolated guinea-pig atrium. Three aptamers (D1, D2 and D3) were identified. Binding studies of fluorescein-labeled truncated (without primer binding region) D1 and D2 and full length D1 anti-digoxin aptamers were performed and their corresponding dissociation constants values were 8.2 × 10⁻⁹, 44.0 × 10⁻⁹ and 17.8 × 10⁻⁹ M, respectively. This is comparable to what other workers have obtained for interaction of monoclonal antibodies raised against digoxin. There was little difference in binding affinity between full length and truncated anti-digoxin D1 aptamer. D1 anti-digoxin aptamer also inhibited the effects of digoxin on the isolated guinea-pig atrium. D1 anti-digoxin aptamer distinguished between digoxin and ouabain in both tissue study and binding experiments. Our finding indicated that D1 anti-digoxin aptamer can selectively bind to digoxin. Further studies might show its suitability for use in digoxin assays and as a therapeutic agent in life-threatening digoxin toxicity.     

Synthesis and aggregation behaviour of amphiphilic block copolymers with random middle block

The effect of microstructure on the aggregation behaviour of symmetrical di- and triblock copolymers P(BMA)-b-P(MAA) and P(BMA)-b-P(BMA-co-MAA)-b-P(MAA) with a molecular weight of 40,000 g/mol was studied. The critical micelle concentration, hydrodynamic radius and morphology of the micelles were determined by fluorescence spectroscopy, dynamic light scattering and scanning force microscopy (SFM). Whereas no effect of the microstructure on the critical micelle concentration could be detected, the hydrodynamic radius decreased from di- to triblock copolymer from 53 to 36 nm. The decrease of about 32% corresponds to the length of the random middle block within the triblock copolymer so that the reduction in hydrodynamic radius was caused by a complete orientation of the random middle block at the core corona interface. Finally, the SFM investigation showed that dehydration of micelles on a substrate is accompanied by formation of a physisorbed monolayer with a thickness of 2 nm on which the micelles are deposited.     

Optical properties of nanostructure boron doped NiO thin films

Boron doped NiO films were prepared by sol–gel method. The effects of B content on the morphological and optical properties of NiO films were studied with atomic force microscopy, and optical characterization method. The average transmittance at the visible region is reached to 75 % for lower doped films (0.1 and 0.2 % B), whereas, the recorded average value of transmittance was about 62 % for doped film with 1 % B throughout the region. The optical energy gap value for pure NiO film was found to be 3.73 eV. These values were affected by B doping with non-monotonic variation and reached to 3.64 eV for 0.1 % B doped NiO. Also, the refractive index dispersion and dielectric constants of the NiO films were studied throughout the investigated range of wavelengths. The obtained results indicate that the optical parameters of the NiO film are controlled with boron doping.     

Synthesis of new transition metal complexes of 1H-perimidine derivatives having antimicrobial and anti-inflammatory activities

New series of 1H-perimidine-2-thiol derivatives and (2-substituted-1H-perimidin-1-yl)ethane-1,2-dione derivatives and their ligands (C₂₄H₁₄N₄S₂O₂) H₂L¹ and (C₂₆H₁₈N₄S₂O₂) H₂L² have been synthesized with transition metal ions, e.g., Copper (II), Silver (I), Cobalt (II) and Ruthenium (III) were prepared and evaluated for their antimicrobial, analgesic and anti-inflammatory activities. The synthesized compounds and their complexes were characterized by elemental analysis, ¹H NMR, IR, MS, molar conductance, thermal gravimetric analysis and electronic spectra. All results revealed that compounds 3 and 13 exhibited high inhibitory effects against some bacterial strains by the disc diffusion method. On the other hand, compounds 2, 3, 7 and 12 displayed potent anti-inflammatory activity.     

Preparation, characterization, and theoretical studies of azelaic acid derived from oleic acid by use of a novel ozonolysis method

Environmentally friendly manufacture of organic compounds has been intensively reexamined in recent years. Many excellent methods have been devised to produce organic compounds from renewable resources. Azelaic acid has been produced by ozonolysis of oleic acid. The reaction was performed in a Bach bubbling reactor, with fine bubbles, at high temperature (150 °C) without utilizing any catalyst or any solvent. Yield of the reaction was 20% after 2 h. Production of azelaic acid was confirmed by use of FT-IR and ¹H NMR spectroscopic data and high-performance liquid chromatography of both synthesized and reference azelaic acid. A theoretical study was performed to obtain quantum chemical data for azelaic acid and to optimize the molecule’s geometry.     

Color Bricks: Building Highly Organized and Strongly Absorbing Multicomponent Arrays of Terpyridyl Perylenes on Metal Oxide Surfaces

Terpyridine‐substituted perylenes containing cyclic anhydrides in the peri position were synthesized. The anhydride group served as an anchor for assembly of the terpyridyl‐crowned chromophores as monomolecular layers on metal oxide surfaces. Further coordination with Zn²⁺ ions allowed for layer‐by‐layer formation of supramolecular assemblies of perylene imides on the solid substrates. With properly selected anchor and linker molecules it was possible to build high quality structures of greater than ten successive layers by a simple and straightforward procedure. The prepared films were stable and had a broad spectral coverage and high absorbance. To demonstrate their potential use, the synthesized dyes were employed in solid‐state dye‐sensitized solar cells, and electron injection from the perylene antennas to titanium dioxide was observed.     

One-pot Synthesis,Crystal Structures and Antimicrobial Activities of Two New 1,4-Disubstituted 1,2,3-Triazole-4-Carboxylates

Two new 1,4-disubstituted 1,2,3-triazoles-4-carboxylates were synthesized via click reaction. Compound 1a was synthesized by the interaction of 6-nitro-tetrazolo[1.5-a]-pyridine with ethyl propynoate at room temperature in the presence of Cu(OAc)2 as a catalyst and THF as solvent. Compound 1b was also synthesized by the same manner except that tert-butyl propionate, instead of ethyl propynoate, was used. The compounds were characterized by IR, 1H-NMR, 13C-NMR and single-crystal X-ray diffraction analysis. Compound 1a(C10H9N5O4) crystallizes in the triclinic system, space group P1 with a = 5.0894(9), b = 8.9834(13), c = 13.089(2) ?, α= 83.041(7), β= 80.256(7), γ=87.296(8)°, V = 585.24(16)?3, Z = 2, Mr = 263.22, crystal size(mm) = 0.37 × 0.20 ×0.18,(I 2σ(I)) = 8557, 2493, 1229, Rint = 0.057. Compound 1b(C12H13N5O4) crystallizes in the monoclinic system, space group P21/c with a = 6.8854(5), b = 21.783(2), c = 9.3986(8) ?,β = 93.239(4)°, V = 1407.4(2)?3, Z = 4, Mr = 291.27, crystal size(mm) = 0.38 × 0.22 × 0.20,(I 2σ(I)) = 11842, 3172, 1866, Rint = 0.047. Antimicrobial assay results showed that the title compounds display excellent activities to different bacterial and fungal strains.