Lamp-based native fluorescence detection of proteins in capillary electrophoresis

The potential of a recently developed lamp-based fluorescence detector for the analysis of underivatised proteins by capillary electrophoresis (CE) was investigated. Fluorescence detection (Flu) was achieved using optical light guides to deliver excitation light from a Xenon–Mercury lamp to the capillary detection window and to collect fluorescence emission and lead it to a photomultiplier. The performance of the detector was evaluated by monitoring the native fluorescence of the amino acid tryptophan and the proteins α-chymotrypsinogen A, carbonic anhydrase II, lysozyme and trypsinogen upon excitation at 280 nm. The test compounds were analysed using background electrolytes (BGEs) of sodium phosphate at pH 3.0 and 11.3. The results were compared to experiments of CE with UV absorbance detection. For tryptophan, a linear fluorescence response was obtained with a dynamic range of over 4 orders of magnitude, and a limit of detection (LOD) of 6.7 nM. This LOD was a factor of 200 more favourable than UV detection at 280 nm, and a factor of 20 better than detection at low-UV wavelengths. All tested proteins showed linear fluorescence responses up to 250 μg/mL. LODs were typically in the 10–20 nM range. These LODs were a factor of 25 lower than for UV detection at 280 nm, and comparable to UV detection at low-UV wavelengths. Overall, Flu yields much more stable baselines, especially with a BGE of high pH. The applicability of CE–Flu is demonstrated by the analysis of a degraded protein mixture, and of an expired formulation of the protein drug human growth hormone, indicating that protein degradation products can be selectively detected.     

Novel tetradentate diamine dioxime ligands: synthesis,characterization and in vivo behavior of their 99mTc‐complexes

Two novel diamine dioxime ligands, 4,7‐diaza‐3,8‐diethyldecane‐2,9‐dione bis oxime (3) and 4,9‐diaza‐3,10‐diethyldodecane‐2,11‐dione bis oxime (5), were synthesized in order to develop new brain perfusion imaging agents, based on ^99mTc(V)‐complexes. The synthesis involved condensation of 2‐hydroxyimino‐3‐pentanone with appropriate diamine in protic solvent which afforded the bis imine adducts. Subsequent reduction of imine functional groups yielded a diastereoisomeric mixture of 3 and 5. UV–visible, IR, ¹H NMR, ¹³C NMR and elemental analysis were used to characterize the structures of the synthesized compounds. ^99mTc‐complexes of both diamine dioximes were prepared and radiolabeling conditions optimized to give the maximum yield. Physicochemical parameters of the labeled complexes as well as and their biodistribution in rats were investigated. Both compounds (3 and 5) formed ^99mTc‐complexes with a net charge of zero, determined by electrophoresis. The resultant lipophilic ^99mTc‐complexes of 3 and 5 were readily formed at pH ~9.0 within 10 min at room temperature with yields of 90% and 95%, respectively. The ^99mTc‐3 complex was found to be stable within 1 h, while ^99mTc‐5 was stable for a few hours. A significant brain uptake of ^99mTc‐3 (2.1% injected dose) and ^99mTc‐5 (1.8% injected dose) complexes, 2 min after injection, is in accordance with their lipophilicity. The present study suggests that both ligands are promising candidates as new ^99mTc‐based brain‐imaging agents. Copyright © 2012 John Wiley & Sons, Ltd.     

Development and optimization of the determination of pharmaceuticals in water samples by SPE and HPLC with diode‐array detection

This paper describes the development, optimization, and validation of a method for the determination of five pharmaceuticals from different therapeutic classes (antibiotics, anthelmintics, glucocorticoides) in water samples. Water samples were prepared using SPE and extracts were analyzed by HPLC with diode‐array detection. The efficiency of 11 different SPE cartridges to extract the investigated compounds from water was tested in preliminary experiments. Then, the pH of the water sample, elution solvent, and sorbent mass were optimized. Except for optimization of the SPE procedure, selection of the optimal HPLC column with different stationary phases from different manufacturers has been performed. The developed method was validated using spring water samples spiked with appropriate concentrations of pharmaceuticals. Good linearity was obtained in the range of 2.4–200 μg/L, depending on the pharmaceutical with the correlation coefficients >0.9930 in all cases, except for ciprofloxacin (0.9866). Also, the method has revealed that low LODs (0.7–3.9 μg/L), good precision (intra‐ and interday) with RSD below 17% and recoveries above 98% for all pharmaceuticals. The method has been successfully applied to the analysis of production wastewater samples from the pharmaceutical industry.     

Calorimetric study and thermal analysis of Al–Sn system

The results of calorimetric study and thermal analysis of binary Al–Sn system are presented in this paper. The Oelsen calorimetry was used in thermodynamic analysis. Following thermodynamic properties were determined at 727 °C: activities, activity coefficients, partial/integral molar Gibbs excess, and mixing energies. The energetics of mixing in liquid Al–Sn alloys has been analyzed through the study of concentration fluctuation in the long-wavelength limit. Thermal analysis of selected alloys in Al–Sn system was done using differential thermal analysis. Defined characteristic phase transition temperatures were used for comparison with calculated phase diagram of investigated system. Good agreement with available literature data was obtained. Structural analysis of selected alloys was done using optic microscopy.     

Application of the fractional factorial design in multiple W/O/W emulsions

In presented research, multiple W/O/W emulsions were developed by using experimental design method. A 24-1 fractional factorial design was performed by varying the following input parameters: primary polymeric emulsifier (PEG 30-dipolyhydroxystearate) concentration (0.8% and 2.4%), secondary polymeric emulsifier (Poloxamer 407) concentration (0.8% and 1.2%), electrolyte magnesium sulfate heptahydrate (0.08% and 0.4%) and electrolyte sodium chloride (0.08% and 0.4%). Multiple emulsions were prepared by a two-step emulsification process. Obtained emulsions were characterized with rheological measurements, conductivity and centrifugation tests. Factorial analysis revealed that the concentration of the primary emulsifier was the predominant factor influencing the phase separation, conductivity and maximal apparent viscosity. Additionally, electrolyte magnesium sulfate heptahydrate was more efficient in stabilizing these systems, compared to sodium chloride. The applied fractional factorial design method enabled determination of the optimal concentrations of the primary and secondary emulsifier, as well as the concentration of electrolytes, in order to obtain W/O/W emulsions with desired maximal apparent viscosities, low values of conductivity and without phase separation after centrifugation.     

Some optical specificity of ultrathin crystalline films

The changes of optical properties under boundary presence in molecular crystal nanofilm were theoretically investigated in this work. The dispersion law and states of excitons as well as their space distribution along boundary direction have been determined using adjusted Green's function method and also by combined analytical and numerical calculations. On the basis of real and imaginary part of relative permittivity, both absorption and refraction indices were determined, and the influences of boundary parameters on occurrence of a very selective and strictly discrete absorption were analyzed.     

Additive results for the generalized Drazin inverse in a Banach algebra

In this paper we investigate additive properties of the generalized Drazin inverse in a Banach algebra. We find some new conditions under which the generalized Drazin inverse of the sum a + b could be explicitly expressed in terms of a, a^d, b, b^d. Also, some recent results of Castro and Koliha [New additive results for the g-Drazin inverse, Proc. Roy. Soc. Edinburgh Sect. A 134 (2004) 1085-1097] are extended.     

Probes for narcotic receptor mediated phenomena. Part 31: Synthesis of rac-(3R,6aS,11aS)-2-methyl-1,3,4,5,6,11a-hexahydro-2H-3,6a-methanobenzofuro[2,3-c]azocine-10-ol, and azocine-8-ol, the ortho-c and the para-c oxide-bridged phenylmorphan isomers

Two of the 12 possible oxide-bridged phenylmorphans, were synthesized, rac-(3R,6aS,11aS)-2-methyl-1,3,4,5,6,11a-hexahydro-2H-3,6a-methanobenzofuro[2,3-c]azocine-10-ol (7) (the ortho-c compound), and rac-(3R,6aS,11aS)-2-methyl-1,3,4,5,6,11a-hexahydro-2H-3,6a-methanobenzofuro[2,3-c]azocine-8-ol (8) (the para-c compound). Single-crystal X-ray diffraction studies indicated that the dihedral angle between the least squares planes through the phenyl ring and the atoms C₁, C_11a, C₁₂, and C₃ in the piperidine ring in both 7·CHCl₃ and 8·HBr was 6.9°. The C₁₂-C_6a-C_6b-C_10a torsion angle was found to be 139.3° for both compounds. The angular relationship between the phenolic ring and the piperidine ring in phenylmorphans that interact with specific opioid receptors as agonists or antagonists is of considerable theoretical interest.     

Liquid-crystalline bisadducts of [60]fullerene

A second-generation cyanobiphenyl-based dendrimer was used as a liquid-crystalline promoter to synthesize mesomorphic bisadducts of [60]fullerene. Liquid-crystalline trans-2, trans-3, and equatorial bisadducts were obtained by condensation of the liquid-crystalline promoter, which carries a carboxylic acid function, with the corresponding bisaminofullerene derivatives. A monoadduct of fullerene was also prepared for comparative purposes. All the compounds gave rise to smectic A phases. An additional mesophase, which could not be identified, was observed for the trans-2 derivative. The supramolecular organization of the monoadduct derivative is governed by steric constraints. Indeed, for efficient space filling, adequacy between the cross-sectional areas of fullerene (approximately 100 A(2)) and of the mesogenic groups (approximately 22-25 A(2) per mesogenic group) is required. As a consequence, the monoadduct forms a bilayered smectic A phase. The supramolecular organization of the bisadducts is essentially governed by the nature and structure of the mesogenic groups and dendritic core. Therefore, the bisadducts form monolayered smectic A phases. The title compounds are promising supramolecular materials as they combine the self-organizing behavior of liquid crystals with the properties of fullerene.     

Synthesis of novel ferrocene-containing 1,3-thiazinan-2-imines: One-pot reaction promoted by ultrasound irradiation

A simple one-pot synthesis of new ferrocene-containing 1,3-thiazinan-2-imines from 3-arylamino-1-ferrocenylpropan-1-ols and phenyl isothiocyanate has been developed. The key intermediate β-hydroxy thioureas were generated in situ using ultrasound irradiation and subsequent cyclization was achieved by the addition of acetic acid. The scope of the reaction towards various 3-arylamino-1-ferrocenylpropan-1-ols has been explored and the corresponding 3-aryl-6-ferrocenyl-N-phenyl-1,3-thiazinan-2-imines were obtained in moderate to high yields (52–90%).