Synthesis and spectral characterization of the first fluorescein-tagged iron(ii) clathrochelates, their supramolecular interactions with globular proteins, and cellular uptake.

A fluorescein-tagged iron(ii) cage complex was obtained in a moderate total yield using a two-step synthetic procedure starting from its propargylamine-containing clathrochelate precursor. An 11-fold decrease in fluorescence quantum yield is observed in passing from the given fluorescein-based dye to its clathrochelate derivative. An excitation energy transfer from the terminal fluorescent group of the macrobicyclic molecule to its quasiaromatic highly π-conjugated clathrochelate framework can explain this effect.

Induced chirality of cage metal complexes switched by their supramolecular and covalent binding.

An ability of the ribbed-functionalized iron(ii) clathrochelates to induce a CD output in interactions with a protein, covalent bonding or supramolecular interactions with a low-molecular-weight chiral inductor, was discovered. The interactions of CD inactive, carboxyl-terminated iron(ii) clathrochelates with serum albumin induced their molecular asymmetry, causing an appearance of strong CD signals in the range of 350-600 nm, whereas methyl ester and amide clathrochelate derivatives remained almost CD inactive. The CD spectra of carboxyl-terminated clathrochelates on supramolecular interactions or covalent bonding with (R)-(+)-1-phenylethylamine gave a substantially lower CD output than with albumin, affected by both the solvent polarity and the isomerism of clathrochelate's ribbed substituents.

Energy Transfer in CeTbF Nanoparticles-CTAB Shell-Chlorin e System.

Formation and electronic excitation energy transfer process in the nanosystem consisting of CeTbF nanoparticles, cetrimonium bromide (CTAB) surfactant, and chlorin e photosensitizer were studied. It was shown that chlorin e molecules bind to CeTbF NP in the presence of CTAB forming thus CeTbF NP-CTAB-chlorin e nanosystem. We consider that binding occurs via chlorin e embedding in the shell of CTAB molecules, formed around NP.

Trimethine cyanine dyes as fluorescent probes for amyloid fibrils: The effect of N,N'-substituents.

The effect of various N,N'-substituents in the molecule of benzothiazole trimethine cyanine dye on its ability to sense the amyloid aggregates of protein was studied. The dyes are low fluorescent when free and in the presence of monomeric proteins, but their emission intensity sharply increases in complexes with aggregated insulin and lysozyme, with the fluorescence quantum yield reaching up to 0.42.

Study of anti-fibrillogenic activity of iron(II) clathrochelates.

The macrocyclic compounds mono- and bis-iron(II) clathrochelates were firstly studied as potential anti-fibrillogenic agents using fluorescent inhibitory assay, atomic force microscopy and flow cytometry. It is shown that presence of the clathrochelates leads to the change in kinetics of insulin fibrillization reaction and reduces the amount of formed fibrils (up to 70%). The nature of ribbed substituent could determine the activity of clathrochelates-the higher inhibitory effect is observed for compounds containing carboxybenzenesulfide groups, while the inhibitory properties only slightly depend on the size of complex species.

Interaction of the iron(II) cage complexes with proteins: protein fluorescence quenching study.

Interaction of the iron(II) mono- and bis-clathrochelates with bovine serum albumin (BSA), β-lactoglobulin, lysozyme and insulin was studied by the steady-state and time-resolved fluorescent spectroscopies. These cage complexes do not make significant impact on fluorescent properties of β-lactoglobulin, lysozyme and insulin. At the same time, the monoclathrochelates strongly quench a fluorescence intensity of BSA and substantially decrease its excited state lifetime due to their binding to this protein.

Hydroxy and methoxy substituted thiacarbocyanines for fluorescent detection of amyloid formations.

In present paper series of trimethine cyanines modified in 5,5'- or 6,6'- position with hydroxy- or methoxy- substituents is studied for their ability to interact selectively with fibrillar formations. Processes of dye aggregation that accompany this interaction were also investigated. Meso-methyl trimethynecyanines with 5,5'- methoxy (7519) and hydroxy (7515) substituents strongly (up to 40 times) increase fluorescence intensity in the presence of fibrillar insulin, and also give noticeable fluorescent response on the presence of various aggregated proteins (lysozyme, β-lactoglobulin, α-synuclein A53T).

Mono and trimethine cyanines Cyan 40 and Cyan 2 as probes for highly selective fluorescent detection of non-canonical DNA structures.

Two of earlier reported dsDNA sensitive cyanine dyes-monomethine Cyan 40 and meso-substituted trimethine Cyan 2 were studied for their ability to interact with non-canonical DNA conformations. These dyes were characterized by spectral-luminescent methods in the presence of G-quadruplex, triplex and dsDNA motifs. We have demonstrated that Cyan 2 binds strongly and preferentially to triple- and quadruple-stranded DNA forms that results in a strong enhancement of the dye fluorescence, as compared to dsDNA, while Cyan 40 form fluorescent complexes preferentially only with the triplex form.

Styryl dyes as two-photon excited fluorescent probes for DNA detection and two-photon laser scanning fluorescence microscopy of living cells.

Spectral-fluorescent properties of benzothiazole styryl monomer (Bos-3) and homodimer (DBos-21) dyes in presence of DNA were studied. The dyes enhance their fluorescence intensity in 2-3 orders of magnitude upon interaction with DNA. Studied styrylcyanines in DNA presence demonstrate rather high values of two-photon absorption (TPA) cross-section, which are comparable with the values of TPA cross section of the rhodamine dyes.

Studies of benzothiazole and benzoselenazole squaraines as fluorescent probes for albumins detection.

Series of squaraine benzothiazole and benzoselenazole dyes were studied as possible fluorescent probes for the detection of proteins, particularly albumins. It was shown that majority of the studied squaraines give significant fluorescent response on the human serum albumin (HSA) and bovine serum albumin presence. For squaraine dyes with N-hexyl pendent groups (P-1, P-2, P-3, P-5) about 100-540-fold fluorescence intensity increase upon albumins addition was observed.

Novel, monomeric cyanine dyes as reporters for DNA helicase activity.

The dimeric cyanine dyes, YOYO-1 and TOTO-1, are widely used as DNA probes because of their excellent fluorescent properties. They have a higher fluorescence quantum yield than ethidium homodimer, DAPI and Hoechst dyes and bind to double-stranded DNA with high affinity. However, these dyes are limited by heterogeneous staining at high dye loading, photocleavage of DNA under extended illumination, nicking of DNA, and inhibition of the activity of DNA binding enzymes.

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.