Study on the interaction of 6-(2-morpholin-4-yl-ethyl)-6H-indolo [2,3-b]quinoxaline hydrochloride with human serum albumin by fluorescence spectroscopy.

Under physiological conditions, in vitro interaction between the bio-active substance 6-(2-morpholin-4-yl-ethyl)-6H-indolo[2,3-b]quinoxaline hydrochloride (MIQ) and human serum albumin (HSA) was investigated at an excitation wavelength 260 nm and at different temperatures (298 K, 308 K and 313 K) by fluorescence emission spectroscopy. From spectral analysis, MIQ showed a strong ability to quench the intrinsic fluorescence of HSA through a static quenching procedure. The binding constant is estimated asK   =  2.

Facile fabrication of luminescent organic dots by thermolysis of citric acid in urea melt, and their use for cell staining and polyelectrolyte microcapsule labelling.

Luminescent organic dots (O-dots) were synthesized via a one-pot, solvent-free thermolysis of citric acid in urea melt. The influence of the ratio of the precursors and the duration of the process on the properties of the O-dots was established and a mechanism of their formation was hypothesized. The multicolour luminescence tunability and toxicity of synthesized O-dots were extensively studied.

Exploring the ability of the nalidixate to sensitize visible and near-infrared emitting lanthanide(III) cations.

Recently, a strong interest has been directed towards near-infrared (NIR) emitting lanthanide(III) compounds as they do possess complementary advantages in respect to organic molecules and semi-conductor nanocrystals, especially in the fields of biological analysis and imaging. To benefit from their emission, a key requirement to fulfill is the sensitization of lanthanide(III) cations with an appropriate chromophore. This condition is especially challenging to address for the lanthanide(III) cations emitting in the NIR.

Sensitive determination of proteins by its quenching effect on fluorescence of new terbium(III) complex.

It is found that in hexamethylenetetramine (HMTA-HCl) buffer pH = 7.8, proteins can quench the fluorescence intensity of new terbium(III) complex with 6-[(1-hydroxy-3-oxo-6,7-dihydro-3H,5H-pyrido[3,2,1-ij]quinoline-2-carbonyl)-amino]-hexanoic acid (L). Based on this, a sensitive fluorimetric method for the determination of proteins is proposed.

The extraction of aromatic carboxylic acids by the copper complex with Curtis macrocyclic tetramine and its utilization for photometric determination of nonsteroidal anti-inflammatory drugs.

Copper complex with Curtis macrocyclic tetramine is offered as reagent for extraction-photometric determination of nonsteroidal anti-inflammatory drugs (NSAIDs), belonging to the class of aromatic carboxylic acids. The studies indicate that this method is suitable for quantitative determination of NSAIDs, which have the constant distribution in the system chloroform/water (log P) no less than 3 and dissolubility in chloroform (S) no less than 10 mg/mL. Under optimum conditions, there are liner relationships between the absorption of chloroform extracts and concentration of NSAID in the range of 0.

Isomorphous substitutions of rare earth elements for calcium in synthetic hydroxyapatites.

Polycrystalline hydroxyapatites Ca(10-x)REE(x)(PO(4))(6)(OH)(2-x)O(x) were synthesized and studied by X-ray powder diffraction, infrared absorption, diffuse-reflectance spectroscopy, and thermogravimetry. The solubility limits x(max) of rare earth elements (REE) in Ca hydroxyapatites decreases with an increasing REE atomic number from x(max) = 2.00 for La, Pr, and Nd to x(max) = 0.

Sensitive luminescent determination of DNA using the terbium(III)-difloxacin complex.

The interaction of the terbium-difloxacin complex (Tb-DFX) with DNA has been examined by using UV-vis absorption and luminescence spectroscopy. The Tb-DFX complex shows an up to 85-fold enhancement of luminescence intensity upon titration with DNA. The long decay times allow additional detection schemes like time-resolved measurements in microplate readers to enhance sensitivity by off-gating short-lived background luminescence.

New luminescent terbium complex for the determination of DNA.

New terbium complexes of derivatives of 2-oxo-4-hydroxy-quinoline-3-carboxylic acid are reported, which are highly luminescent, water soluble and do not require luminescence enhancers. The triplet-state energy levels of the ligands, the relative quantum yields (QYs) and the excitation maxima of the respective terbium chelates were determined. The large luminescence enhancement of one of these complexes by nucleic acids was investigated and a mechanism of its interaction with DNA is proposed.

[The comprehensive diagnosis of changes in the stomach and small intestine in patients with chronic colitis].

Combined investigation of 121 patients with chronic colitis (CC) has shown chronic gastroduodenitis in 90.9% and the intestinal malabsorption syndrome in all the patients. Comparison of the frequency of intestinal malabsorption symptoms has shown that they are less marked in CC than in chronic enterocolitis with predominant intestinal lesion.

[Clinico-roentgeno-endoscopic and morphologic (morphometric) correlations in chronic non-ulcerative colitis].

Proceeding from the correlation of x-ray, endoscopic and morphological (morphometric) findings the authors defined significant x-ray symptoms (including enlarged lymphoid follicles of various sizes) of chronic nonulcerative colitis.

Photometric determination of tungsten in rocks with trihydroxyfluorones.

The interaction of tungsten(VI) with a series of 2,3,7-trihydroxyfluorones in the presence of cationic and non-ionic surfacants has been studied. Optimal conditions for the formation of the complexes and their spectrophotometric determination have been found. Possible mechanisms for the effect of the surfactants are suggested.