An Investigation of Tricarbocyanines “Stains-All” and “iso-Stains-All” as Fluorescent Nucleic Acids Probes

Luminescent properties of carbocyanine dyes Stains-All and its isomer iso-Stains-All were studied in the presence of nucleic acids. Both dyes show sufficient fluorescent intensity increase in the presence of DNA and RNA and may be used as fluorescent probes for nucleic acids (NA) detection in homogeneous assays. It was supposed that Stains-All and iso-Stains-All bind with nucleic acids through different interaction modes.     

Tri- and Pentamethine Cyanine Dyes for Fluorescent Detection of α-Synuclein Oligomeric Aggregates

The pathogenesis of Parkinson’s disease that is the second most common neurodegenerative disease is associated with formation of different aggregates of α-synuclein (ASN), namely oligomers and amyloid fibrils. Current research is aimed on the design of fluorescent dyes for the detection of oligomeric aggregates, which are considered to be toxic and morbific spices. Fluorescent properties of series of benzothiazole trimethine and pentamethine cyanines were characterized in free state and in presence of monomeric, oligomeric and fibrilar ASN. The dyes with wide aromatic systems and bulky phenyl and alkyl substituents that are potentially able to interact with hydrophobic regions of oligomeric aggregates were selected for the studies. For majority of studied dyes noticeable changes in fluorescence characteristics were shown in the presence of fibrillar or oligomeric ASN, while the dyes slightly responded on the presence of monomeric protein. For pentamethine cyanine SL-631 and trimethine cyanine SH-299 certain specificity to oligomeric aggregates over fibrils was observed. Using these dyes at 10^?6 M concentration permits the detection of oligomeric ASN in the concentrations range of at least 0.2–2 microM. Pentamethine cyanine SL-631 is proposed as dye for fluorescent detection of oligomeric aggregates of ASN, while trimethine cyanine SH-299 is shown to be a sensitive probe both on oligomeric and fibrillar ASN. It is proposed that wide aromatic system of SL-631 pentamethine dye molecule could better fix on the less dense and structured oligomeric formation, while less bulky and more “crescent-shape” molecule of trimethine dye SH-299 could easier enter into the groove of beta-pleated structure.     

Quino-4-cyanines with carbonyl-containing substituents

6-Carbonyl-substituted lepidines and their quaternary salts were synthesized. Quino-4-cyanines were obtained from them. The introduction of carbonyl-containing substituents substantially deepens the color of the dyes obtained.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 943–947, July, 1984.     

Infrared electroluminescence of organic nanocrystals in polymer composites

Electroluminescent polymeric nanocomposite structures that are based on aromatic polyimides and cyanine dye nanosized crystals known as J aggregates and emit light in the IR region were prepared. For the first time, doped polymer systems were found to display IR luminescence whose spectrum had the form of a very narrow band that peaked at 1100 nm. Nanosized J-aggregate crystals in these new polymer materials act not only as effective acceptors of energy of excitonic states but also as active electron-hole transport sites.     

Interaction of chromophores in dissimilar associates of cationic and anionic polymethine dyes in water

A strong interaction between chromophores of cationic and anionic components was found based on the analysis of electronic absorption spectra of aqueous solutions of mixtures of cationic indopolycarbocyanines with anionic cyanines. Strong dissimilar 1∶1 associates are formed. Association constants were estimated spectrophotometrically. The main factors determining the degree of interaction of chromophores were revealed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 950–955, May, 1997.     

Infrared Electroluminescence in Polymer Composites Based on Organic Nanocrystals

Electroluminescence in polymer nanocomposite structures with electron–hole transport, called J-aggregates, which are based on aromatic polyimides and nanosized crystals of cyanine dyes, is studied. In the near-IR range, the electroluminescence with a narrow emission spectrum (with a maximum at 815 nm) is observed for the first time. It is shown that not only are the organic nanosized crystals of the J-aggregates effective acceptors of the exciton state energy, but they play the role of active electron–hole transport centers in these novel polyfunctional polymer materials.     

Fluorescent Properties of Pentamethine Cyanine Dyes with Cyclopentene and Cyclohexene Group in Presence of Biological Molecules

A series of pentamethine cyanine dyes with cyclohexene or cyclopentene group in polymethyne chain, assumed as DNA groove-binders, were studied as fluorescent probes for nucleic acids as well as for native and denatured proteins. It was revealed that the presence of methyl or dimethyl substituent in 5 position of the cyclohexene group hinders the formation of dye–DNA fluorescent complex, while the methyl substituent in 2 position leads to the increasing of the dye–DNA complex fluorescence intensity. The dyes SL-251, SL-1041, and SL-1046 containing methyl group in the 2 position of the cyclic group, are reported as bright DNA-sensitive dyes. The study of the dyes DNA-binding specificity demonstrated significant AT-preference that points to the groove-binding interaction mode. At the same time, the dyes SL-251, SL-377, and SL-957 with the 2-methyl substituted cyclohexene group were shown to be sensitive fluorescent dyes both for nonspecific (in SDS presence) proteins detection and for native BSA.     

Mixed J Aggregates of Oxacarbocyanine Dyes and Their Photographic Properties

Formation of mixed J aggregates from two oxacarbocyanine dyes of different structures was established. Mixed J aggregates were shown to be photographically active states of spectral sensitizers. The fundamental conclusion was made that the photosensitization maximum and the photographic activity of mixed J aggregates can be varied over a wide range by changing the concentration of the dyes incorporated into the aggregates.