Specificity of Cyanine Dye L-21 Aggregation in Solutions with Nucleic Acids

Optical spectroscopy experiments were used to study the features of cyanine dye 3,3′-dimethyl-9-(2-thienyl)-thiacarbocyanine iodide (L-21) aggregation in binary solutions DMF:Tris–HCl buffer (pH = 8) containing nucleic acids (DNA or RNA). The appearance of absorption and luminescence bands associated with J-aggregates and dimers that are formed within the minor groove of DNA has been observed. The model of L-21 J-aggregate structure is proposed. It has been found that dimers are the building blocks of L-21 J-aggregates. Disorientation in dimers caused by the minor groove curvature is reason of observation of Davydov splitting in absorption spectrum of L-21 J-aggregates. In the solution containing DNA the absorption and luminescence bands of L-21 J-aggregates exhibit the specific properties that allows the dye L-21 to be used as a fluorescent probe for DNA detection.     

New Approach for Fluorescent Peptide Labeling with Pyrylium Cyanine Dyes

New approach for fluorescent peptide labeling with cyanine dyes utilizing the reaction of pyrylium salts with aliphatic aminogroup is proposed. The reaction of two pyrylium cyanines dye acids was investigated. Lysocyme was used as a model peptide for conjugation. The proposed method can be used as a simple and convenient alternative for the known procedures because it does not require preparation of the unstable amino-reactive intermediates from a carboxyl- or sulfo-derivative of cyanine dyes.     

6,6'-Disubstituted benzothiazole trimethine cyanines--new fluorescent dyes for DNA detection

The influence of methyl-, 2-hydroxyethyl-, dimethyl-, diethyl- and benzoyl-amino substituents in the 6,6'-positions of benzothiazole heterocycle of trimethine cyanines on their spectral-luminescent properties and behavior in presence of DNA, RNA and BSA was studied. It was shown that incorporation of 6,6'-substituents generally leads to the increase in dyes tendency to aggregation, resulting in the considerable decrease in the emission intensity of the disubstituted dyes as compared to the unsubstituted ones. Emission of the studied 6,6'-disubstited dyes in DNA presence is considerably more intensive than in presence of RNA, that points on the existing of DNA binding preference for the mentioned dyes. Insertion of benzoyl-amino groups into the 6,6'-positions permitted us to design the DNA-sensitive dyes on the basis of symmetric trimethine cyanines with unsubstituted polymethine chain, while typically such dyes slightly respond on the presence of biopolymers. 6,6'-Benzoyl-amino-disubstituted trimethine cyanines are proposed as efficient dyes for DNA detection.     

Simple Zeros of the Riemann Zeta-Function

Assuming the Riemann Hypothesis, Montgomery showed by meansof his pair correlation method that at least two-thirds of thezeros of Riemann's zeta-function are simple. Later he and Taylorimproved this to 67.25 percent and, more recently, Cheer andGoldston increased the percentage to 67.2753. Here we proveby a new method that if the Riemann and Generalized LindelöofHypotheses hold, then at least 70.3704 percent of the zerosare simple and at least 84.5679 percent are distinct. Our methoduses mean value estimates for various functions defined by Dirichletseries sampled at the zeros of the Riemann zeta-function. 1991Mathematics Subject Classification: 11M26.     

Studies on the Spectral-Luminescent Properties of the Novel Homodimer Styryl Dyes in Complexes with DNA

Series of homodimer styryls containing on (p-dimethylaminostyryl) pyridinium residues that are connected with aliphatic linkage group was synthesized. Spectral luminescent properties of obtained dyes in free state and in nucleic acids presence were studied. It was shown that DNA binding affinity of the novel homodimers exceeds that of parent monomer (p-dimethylaminostyryl)pyridine iodide. For homodimers with the linkage 4–10 carbon atoms preference in binding to DNA than to RNA was observed. It could be concluded that parent monomer has different mechanisms of binding to nucleic acids than corresponding homodimer dye.     

Quantum Zeno and anti-Zeno paradoxes

Continuous observation of a time independent projection operator is known to prevent change of state (the quantum Zeno paradox). We discuss the recent result that generic continuous measurement of time dependent projection operators will in fact ensure change of state: an anti-Zeno paradox.     

Influence of the Aggregation of Homo-N-Mer Cyanine Dyes on the Nucleic Acids Detection Sensitivity

Novel benzothiazolopyridinium homo-n-mer cyanine dyes are proposed for nucleic acid fluorescent detection. Dependence of the sensitivity of detection in solution from the dye molecules/DNA base pairs ratio was studied. It was shown that the presence of the dye excess could significantly decrease the detection limit. We believe this could be explained by the formation of the dye aggregates on DNA surface.