Monomethine Cyanine Dyes Research Articles

Полиморфные структуры монослойных J-агрегатов двух монометиновых цианиновых красителей в мезо- и наномасштабе

Полиморфные структуры монослойных J-агрегатов двух монометиновых цианиновых красителей в мезо- и наномасштабе

Non-cytotoxic photostable monomethine cyanine platforms: Combined paradigm of nucleic acid staining and in vivo imaging

Cyanine based chemosensing platforms have successfully been employed over the past couple of decades in various fields of biomolecular sciences. Still a substantial number of recent advances and improvements on this class of compounds are reported in the art. This paper presents our latest work on the improved synthetic approach, study on photophysical properties, and biosensing applicability of monomethine cyanine dyes. The series of mono-, di- and tricationic dyes showed up to 5-fold enhanced resistance against photobleaching compared to the commercially available Thiazole Orange (TO). The title compounds were studied as potential molecular probes for the detection of deoxyribonucleic acid, demonstrating their capacity as excellent fluorescent labeling agents. Depending on the dye chemical structure, current Cl-TO compounds exhibit up to 834-fold enhanced fluorescence emission and form stable complexes with Calf Thymus-DNA. The calculated binding constants were found to be higher than several conventional fluorogenic dyes for nucleic acid detection. All studied derivatives appeared as less cytotoxic than the Thiazole Orange. IC50 concentrations in human fibroblasts MRC5 cell line were calculated up to 50 μM for the synthesized Cl-TO dyes, and 0.5 μM for the parental Thiazole Orange. Two of the dyes were found very competent in post-electrophoretic visualization of DNA. As demonstrated by the agarose gel electrophoresis, the staining efficiency and detection limits of the dyes were comparable to the widely used Ethidium Bromide. The tricationic dye revealed great potential for cell cycle analysis in G1, S and G2 phases. The chlorinated TO derivatives readily stain human cells in vivo, while they can effectively be applied for eukaryotic and microbial cell staining.

Spectroscopic and molecular docking studies of the interactions of monomeric unsymmetrical polycationic fluorochromes with DNA and RNA

The photophysical properties of a series of unsymmetrical di- and tricationic monomethine cyanine dyes were studied in the presence of nucleic acids using combined spectroscopic techniques and molecular docking. The analysis of the UV–visible absorption and the fluorescence spectra revealed a strong association of the title cyanines with nucleic acids, while the interaction magnitude is notably higher for the double-stranded DNA, compared to that of the single-stranded RNA. The binding parameters of the cyanine dyes were determined in terms of the McGhee & von Hippel neighboring site-exclusion model. Cumulatively, the results from the optical spectroscopy measurements along with those from the molecular docking analysis were found to be consistent, presuming minor groove binding motif as predominant between the examined cyanines and deoxyribonucleic acid, whereas external binding upon biocomplexation with ribonucleic acid.

Association of novel monomethine cyanine dyes with bacteriophage MS2: A fluorescence study

Novel monomethine cyanine dyes Cl-YO, F-YO, Cl-YO-Et, Cl-YO-Bu, and YO-Pent were evaluated as agents to detect and characterise a small virus, the MS2 bacteriophage, using the dye and virus intrinsic fluorescence, kinetic and thermal properties, chemical denaturation, and molecular docking and quantum chemistry modelling. The examined compounds demonstrated enhanced fluorescence responses and high affinities (~1 μM−1) for the intact bacteriophage at physiological ionic strength. The linear Scatchard plots revealed the existence of one binding mode for most dyes. Strong evidence that the cyanines bind to the bacteriophage external surface were obtained, although the possibility of the dye penetration through the virus shell and subsequent complexation with the viral RNA was also tested. The main arguments in favour of the former were that i) the fluorescence of the MS2-bound fluorophores decreased under the influence of protein denaturants, urea and guanidine hydrochloride; ii) the fluorescence responses of the dyes to MS2 and bovine serum albumin were similar; and (iii) one order of magnitude higher sensitivity of the dyes to the yeast RNA was found. Simple docking studies suggested that one cyanine molecule is trapped in a cleft formed by three proteins composing the virus shell. Significant role of electrostatic forces in the stabilisation of the dye-MS2 complexes at low ionic strength (10 mM) was demonstrated, while the influence of steric, hydrophobic, and van-der-Waals interactions was expected to increase at physiological ionic strength. The spectral properties of the novel cyanine dyes compared to other fluorophores demonstrated higher sensitivity of the cyanines to MS2, rendering them promising agents for the investigation of the changes in the virus structure under the influence of heat (Cl-YO-Et, Cl-YO-Bu), denaturants (Cl-YO, F-YO), and ionic strength (all the compounds).

Sulfenic Acid-Directed Chemical Probes and Workflows for Assessing Protein Oxidation

Cyanine based chemosensing platforms have successfully been employed over the past couple of decades in various fields of biomolecular sciences. Still a substantial number of recent advances and improvements on this class of compounds are reported in the art. This paper presents our latest work on the improved synthetic approach, study on photophysical properties, and biosensing applicability of monomethine cyanine dyes. The series of mono-, di- and tricationic dyes showed up to 5-fold enhanced resistance against photobleaching compared to the commercially available Thiazole Orange (TO). The title compounds were studied as potential molecular probes for the detection of deoxyribonucleic acid, demonstrating their capacity as excellent fluorescent labeling agents. Depending on the dye chemical structure, current Cl-TO compounds exhibit up to 834-fold enhanced fluorescence emission and form stable complexes with Calf Thymus-DNA. The calculated binding constants were found to be higher than several conventional fluorogenic dyes for nucleic acid detection. All studied derivatives appeared as less cytotoxic than the Thiazole Orange. IC50 concentrations in human fibroblasts MRC5 cell line were calculated up to 50 μM for the synthesized Cl-TO dyes, and 0.5 μM for the parental Thiazole Orange. Two of the dyes were found very competent in post-electrophoretic visualization of DNA. As demonstrated by the agarose gel electrophoresis, the staining efficiency and detection limits of the dyes were comparable to the widely used Ethidium Bromide. The tricationic dye revealed great potential for cell cycle analysis in G1, S and G2 phases. The chlorinated TO derivatives readily stain human cells in vivo, while they can effectively be applied for eukaryotic and microbial cell staining.

Polynuclear Heterocyclic Monomethine and Trimethine Cyanine Dyes: Synthesis and Various Absorption Spectra Studies

Polynuclear Heterocyclic Monomethine and Trimethine Cyanine Dyes: Synthesis and Various Absorption Spectra Studies

Oxonium Salts in the Synthesis and Spectral Behavior of Pyrano(pyrylium)‐mono methine Cyanine Dyes

Pyrano‐ and pyrylium mono‐8[4(1)] and/or 5(6)‐[2(4)]methine cyanine dyes (6a–k, 7a–f) were synthesized based on acyclic heterocyclic Schiff bases of pyrolo[3,2‐d]pyrazole[oxazole(imidazol‐6‐one)]‐1‐ium iodide salts, 5‐acetyl‐N‐aryl[pyrazolinyl(pyridinyl)]pyrolo‐[5,4‐d]pyrazolin‐iodide salts, and/or (anhydro bases) precursors (1a–i, 2a–I, 3a–i, 4a–i, and 5A,Ba–i). The structure of pyrylium‐9‐chloride and/or iodide and their pyrano(pyrylium)‐mono‐8[4(1)] and 5(6)[2(4)]methine cyanine dyes was identified by elemental and spectral data. The absorption spectra of some selected dyes were investigated in 95% EtOH, polar (nonpolar) organic solvents and in universal buffer solutions to investigate the optimal conditions for the application of such dyes as photosensitizers.

Hybrid organic and inorganic solar cell based on a cyanine dye and quantum dots

The combination of organic dyes with quantum dots (QDs) in solar cells can lead to more improvement in photovoltaic performance for such types of solar cells. Due to the quantum confinement, the photoluminescence (PL) of QDs can be tuned to match the absorption spectra of applied organic dyes. Herein, we introduce a new hybrid solar cell based on monomethine cyanine dye co-sensitized by CdS and CdTe/CdS core shell. The cyanine dye tends to aggregate on the surface of colloidal QDs due to electrostatic attraction followed by energy and electron transfer from QDs to cyanine dye. Electrophoretic deposition method was carried out to assist the cyanine dye loading on the surface of TiO2 thin film and the highest power conversion efficiency was 0.89% in case of cyanine dye co-sensitized by CdTe/CdS with open circuit voltage of 0.78 V and a photocurrent of 1.80 mA/ cm2.

Brewing yeast viability measured using a novel fluorescent dye and image cytometer

This study presents an automated, image-based cytometry method for determination of total counts and viability of yeast cells by using a newly synthesized DNA fluorescent dye PO-TEDM-1 and a new Easycounter YC instrument. The synthesized polycationic asymmetric monomethine cyanine dye PO-TEDM-1 penetrates only into dead cells. The new fluorescent dye has high nucleic acid sensitivity and rapid interaction kinetics. The optimal concentration of the fluorescent dye for staining dead cells was 1 µg mL−1. The Easycounter YC system was used to determine the total cell count and viability of Saccharomyces carlsbergensis. The actual viability measured using the proposed method significantly correlated with the theoretical viability (R2 of 0.9988). The optimal linear interval was from 1 × 105 to 1 × 107 cells mL−1. The coefficient of variation with Easycounter YC in the optimal range was 2.5–4%, whereas that of the manual hemocytometry method, in the same range was higher, 15–23%. We tested the procedure in a study of the total cell count and viability of yeast cells from the propagators in beer production as a function of the dilution. The proposed method can be used in assays involving simple cell counting and quality assurance in sample bioprocessing.

Synthesis, Electronic Transitions and Antimicrobial Activity Evaluation of Novel Monomethine and Trimethine Cyanine Dyes

Synthesis, Electronic Transitions and Antimicrobial Activity Evaluation of Novel Monomethine and Trimethine Cyanine Dyes

Bright green-emitting ds-DNA labeling employed by dicationic monomethine cyanine dyes: Apoptosis assay and fluorescent bio-imaging

Fluorescent based techniques are among the state-of-the-art detection methods utilized for both qualitative and quantitative investigations in biochemical and biomedical sciences. The essential methods for evaluation of apoptosis and cell cycle by measuring DNA content using flow cytometry and imaging experiments, such as fluorescent microscopy are extensively being used for staining of live and/or apoptotic cells. Among a wide diversity of commercially available fluorescent dyes, cyanine-based non-covalent labeling has been employed for several years as fluorescent probes mainly due to their capabilities for biological applications upon binding to nucleic acids.Three novel asymmetric dicationic monomethine cyanine dyes derived from 2-thiomethylbenothiazolium and 4-methylquinolinium salts were synthesized and have been tested for potential applicability in biological research as fluorescent labels for nucleic acids detection. The newly obtained cyanine probes became highly fluorescent upon addition of ds-DNA according to a well-known mechanism of this class of organic compounds. Employing flow cytometry and fluorescent microscopy, the dyes were evaluated in live-dead cells discrimination. Moreover, FACS studies on 3T3 mouse embryonic fibroblast cells verified their inability to penetrate through intact plasma membrane. Further in-depth studies on the dyes, outline their capability for estimations of cell viability and staining late apoptotic/necrotic cells.Imaging experiments by means of fluorescent microscopy, delineate the dyes' high specificity towards ds-DNA and allowed nuclear morphology imaging of non-living ethanol-fixed cells.

Halogen-containing thiazole orange analogues - new fluorogenic DNA stains.

Novel asymmetric monomeric monomethine cyanine dyes 5a–d, which are analogues of the commercial dsDNA fluorescence binder thiazole orange (TO), have been synthesized. The synthesis was achieved by using a simple, efficient and environmetally benign synthetic procedure to obtain these cationic dyes in good to excellent yields. Interactions of the new derivatives of TO with dsDNA have been investigated by absorption and fluorescence spectroscopy. The longest wavelength absorption bands in the UV–vis spectra of the target compounds are in the range of 509–519 nm and these are characterized by high molar absorptivities (63000–91480 L·mol−1·cm−1). All investigated dyes from the series are either not fluorescent or their fluorescence is quite low, but they become strongly fluorescent after binding to dsDNA. The influence of the substituents attached to the chromophores was investigated by combination of spectroscopic (UV–vis and fluorescence spectroscopy) and theoretical (DFT and TDDFT calculations) methods.

New series of non-toxic DNA intercalators, mitochondria targeting fluorescent dyes

Five novel benzoxazolium and benzothiazolium derived asymmetric dicationic monomethine cyanine dyes, bearing a thioester group have been synthesised via condensation of quaternary nitrogen containing heterocyclic salts in various anhydrides. Their chemical structures were evaluated by NMR, ESI/MS, IR spectroscopy, and melting point temperatures. Photophysical studies on the title compounds were performed in methanol solutions. The longest wavelength absorption maxima λmax of the studied dyes are in the region 453–508 nm. The corresponding fluorescence maxima λfl were registered within the 489–553 nm. Further spectroscopy and calorimetric techniques including circular dichroism (CD), UV–Vis, fluorescence, thermal denaturation and isothermal titration calorimetry have been applied to the studied dyes in the presence of biopolymers, in order to evaluate their staining ability as fluorescent markers. In aqueous solution the compounds exhibit no intrinsic fluorescence, however upon binding to dsDNA and dsRNA they show considerable enhancement of fluorescence intensity. Binding constants Ks of the complexes [dye–polynucleotide] have been evaluated from fluorescence spectral titrations. Although the intercalation is the predominant binding mode, the compounds show little or no effect on the cell proliferation. Upon fast cell internalization the compounds accumulate in the mitochondrial space.

Polymorphism of 2D monolayer J-aggregates of cyanine dyes

Meso- and nanoscale structural polymorphism of monolayer J-aggregates of four cyanine dyes are investigated. Three mesoscale morphological types are observed: ribbons, rhombic leaves, and tubes. Tubes are formed during cylindrical spinning of ribbons. Lined substructure characterized by the line width of about 7 nm is found in the case of monolayers of monomethine cyanine dyes at the nanoscale.

Synthesis, Spectral Sensitization, Solvatochromic and Halochromic Evaluation of New Monomethine and Trimethine Cyanine Dyes

Synthesis, Spectral Sensitization, Solvatochromic and Halochromic Evaluation of New Monomethine and Trimethine Cyanine Dyes

“Turn on” fluorescence response of monomethine cyanines caused by noncovalent binding to ct-DNA

Monomethine cyanines have been extensively studied for their use as probes for nucleic acids among other biological systems. Four monomethine cyanine dyes were synthesized with various heterocyclic moieties including quinoline, benzoxazole, benzothiazole, and 3,3-dimethylindolenine adjoining benz[c,d]indol-1-ium, which was found to directly influence their optical and energy profiles. The dyes were characterized by 1H and 13C NMR and HRMS. In this study the twisted conformation unique to monomethine cyanines was exploited in DNA binding studies where the benzoxazole containing sensor displayed up to 700-fold increase in fluorescence when bound to the DNA compared to the unbound form.

Photo-induced interaction of thioglycolic acid (TGA)-capped CdTe quantum dots with cyanine dyes

The photo-induced interaction of three different sizes of thioglycolic acid (TGA)-capped CdTe quantum dots (CdTe QDs) with two monomethine cyanine dyes belonging to the thiazole orange (TO) family has been studied. Positively charged cyanines interact with QDs surface which is negatively charged due to capping agent carboxylate ions. The energy transfer parameters including Stern-Volmer constant, Ksv, number of binding sites, n, quenching sphere radius, r, the critical energy transfer distance, R0, and energy transfer efficiencies, E have been calculated. The effect of structure and the number of aggregating molecules have been studied as a function of CdTe QDs particle size. Combining organic and inorganic semiconductors leads to increase of the effective absorption cross section of the QDs which can be utilized in novel nanoscale designs for light-emitting, photovoltaic and sensor applications. A synthesized triplet emission of the studied dyes was observed using CdTe QDs as donors and this is expected to play a potential role in molecular oxygen sensitization and in photodynamic therapy (PDT) applications.

Efficient green synthesis of monomethine cyanines via grinding under solvent-free conditions

Abstract A solvent-free, efficient, and green approach for the synthesis of monomethine cyanine dyes was carried out via grinding at room temperature in the presence of a minimum amount of catalyst. This green methodology aims to overcome the limitations and drawbacks of previously reported methods such as heating at high temperatures, use of large amounts of catalysts, use of solvents, modest yields, and long reaction times. Moreover, the advantages of the process include mild conditions with excellent conversion, and inexpensive procedure. The new synthetic method was demonstrated for eight reported dyes, as representatives, and showed high applicability for their analogues in the same way. The green context of the new methodology was noticeable, compared with the non-green components of the conventional one. The structure and purity of the resulting compounds were compared with the previously reported data and confirmed using thin layer chromatography, absorption spectra, elemental analysis, mass spectrometry, 1H-nuclear magnetic resonance (NMR) and 13C-NMR spectroscopy.

Novel asymmetric monomethine cyanine dyes derived from sulfobetaine benzothiazolium moiety as potential fluorescent dyes for non-covalent labeling of DNA

Four novel monomethine cyanine dyes derived from a condensation reaction between N-quaternary 2-thiomethylbenzothiazolic, and 4-methylquinolinuim choromophores have been synthesized and characterized by 1H NMR, APT carbon NMR, ESI mass spectrometry, IR, absorption and fluorescence spectroscopy. The main synthetic approach for the target cyanines involves variations on both the substituent on the aromatic ring of the benzothiazolium derivative, as well as the size of the component yielding the additional positive charge linked to the quinolinium moiety. The interaction between novel fluorophores and dsDNA has been studied. The dyes were found to have negligible fluorescence in the buffer solution, but exhibited a significant emission increase upon binding to dsDNA. The binding parameters of cyanine dyes have been determined by fluorescence titration using the McGhee & von Hippel site-excluded model. The results obtained are consistent with an intercalative binding mode between cyanines and DNA.

Benz[c,d]indolium-containing Monomethine Cyanine Dyes: Synthesis and Photophysical Properties.

Asymmetric monomethine cyanines have been extensively used as probes for nucleic acids among other biological systems. Herein we report the synthesis of seven monomethine cyanine dyes that have been successfully prepared with various heterocyclic moieties such as quinoline, benzoxazole, benzothiazole, dimethyl indole, and benz[e]indole adjoining benz[c,d]indol-1-ium, which was found to directly influence their optical and energy profiles. In this study the optical properties vs. structural changes were investigated using nuclear magnetic resonance and computational approaches. The twisted conformation unique to monomethine cyanines was exploited in DNA binding studies where the newly designed sensor displayed an increase in fluorescence when bound in the DNA grooves compared to the unbound form.