Water-soluble Fluorescent Dye Research Articles

Water-Soluble Fluorescent Polymer Dyes with Tunable Emission Spectra for Flow Cytometry Applications.

The application of spectrally unique, bright, and water-soluble fluorescent dyes is indispensable for the analysis of biological systems. Multiparameter flow cytometry is a powerful tool for characterization of mixed cell populations. To discriminate the different cell populations, they are typically stained by a set of fluorescent reagents, e.g., antibody-fluorophore conjugates. The number of parameters which can be studied simultaneously strongly depends on the availability of reagents which can be differentiated by their spectral properties. In this study a series of fluorescent polymer dyes was developed, that can be excited with a single violet laser (405 nm) but distinguished by their unique emission spectra. The polyfluorene-based polymers can be used on their own, or in combination with covalently bound small-molecule dyes to generate energy transfer constructs to red-shift the emission wavelength based on Förster resonance energy transfer (FRET). The polymer dyes were utilized in a biological flow cytometry assay by conjugating several of them to antibodies, demonstrating their effectiveness as reagents. This report represents the first systematic investigation of structure-property relationships for this type of fluorescent dyes.

PH-responsive niosome-based nanocarriers of antineoplastic agents.

Differences in pH between the tumour interstitium and healthy tissues can be used to induce conformational changes in the nanocarrier structure, thereby triggering drug release at the desired site. In the present study, novel pH-responsive nanocarriers were developed by modifying conventional niosomes with hexadecyl-poly(acrylic acid)n copolymers (HD-PAAn). Niosomal vesicles were prepared by the thin film hydration method using Span 60, Span 60/Tween 60 and cholesterol as main constituents, and HD-PAA modifiers of different concentrations (0.5, 1, 2.5, 5 mol%). Next, two model substances, a water-soluble fluorescent dye (calcein) and a hydrophobic agent with pronounced antineoplastic activity (curcumin), were loaded in the aqueous core and hydrophobic membrane of the elaborated niosomes, respectively. Physicochemical properties of blank and loaded nanocarriers such as hydrodynamic diameter (Dh), size distribution, zeta potential, morphology and pH-responsiveness were investigated in detail. The cytotoxicity of niosomal curcumin was evaluated against human malignant cell lines of different origins (MJ, T-24, HUT-78), and the mechanistic aspects of proapoptotic effects were elucidated. The formulation composed of Span 60/Tween 60/cholesterol/2.5% HD-PAA17 exhibited optimal physicochemical characteristics (Dh 302 nm; ζ potential -22.1 mV; high curcumin entrapment 83%), pH-dependent drug release and improved cytotoxic and apoptogenic activity compared to free curcumin.

Indocyanine green dye and its application in gastrointestinal surgery: The future is bright green.

Indocyanine green (ICG) is a water-soluble fluorescent dye that is minimally toxic and widely used in gastrointestinal surgery. ICG facilitates anatomical identification of structures (e.g., ureters), assessment of lymph nodes, biliary mapping, organ perfusion and anastomosis assessment, and aids in determining the adequacy of oncological margins. In addition, ICG can be conjugated to artificially created antibodies for tumour markers, such as carcinoembryonic antigen for colorectal, breast, lung, and gastric cancer, prostate-specific antigen for prostate cancer, and cancer antigen 125 for ovarian cancer. Although ICG has shown promising results, the optimization of patient factors, dye factors, equipment, and the method of assessing fluorescence intensity could further enhance its utility. This review summarizes the clinical application of ICG in gastrointestinal surgery and discusses the emergence of novel dyes such as ZW-800 and VM678 that have demonstrated appropriate pharmacokinetic properties and improved target-to-background ratios in animal studies. With the emergence of robotic technology and the increasing reporting of ICG utility, a comprehensive review of clinical application of ICG in gastrointestinal surgery is timely and this review serves that aim.

Surfactant micellar induced aggregation control of an anionic fluorescent dye in Langmuir-Blodgett film

This work reports the formation of stable Langmuir monolayer of an anionic water soluble fluorescent dye 5(6)-carboxyfluorescein (abbreviated as CFS) by electrostatic interaction with a cationic monolayer. Formation of non-fluorescent H-dimeric sites of CFS molecules in Langmuir monolayer and Langmuir Blodgett films has been controlled by using cationic surfactant micelles of cetyltrimethylammonium bromide (CTAB). Thus the film can act as efficient fluorescence marker. Langmuir monolayer has been investigated by Surface Pressure versus Area per molecule (π-A) isotherm and in situ Brewster Angle Microscope (BAM) studies. Mono and multilayered Langmuir Blodgett films were characterized by using UV–vis absorption and steady state fluorescence spectroscopy.

Towards a cost-effective modeling of fluorescence in the condensed phase

We propose a synergistic computational/experimental investigation of fluorescence spectra in aqueous solution. As a powerful tool to analyze and interpret experimental findings, we develop a reliable and cost-effective computational protocol, which is able to correctly describe the solute-solvent interactions which can highly affect the spectral signal. To this purpose, the model not only takes into account specific, strong hydrogen bonding interactions, but also the dynamical aspects of the solvation phenomenon in both the ground and, remarkably, excited state. The computational protocol is tested against the reproduction of experimentally measured spectra of representative water soluble fluorescent dyes. An almost perfect agreement is reported, thus confirming the reliability of the methodology, that paves the way for a cost-effective investigation of ES properties of solvated systems.

Impact of polyelectrolyte complex layer on the stability of palm oil multiple emulsions encapsulating a water-soluble compound during heating, cooling, and storage processes

The effect of an interfacial polyelectrolyte complex layer on the stability of multiple water-in-oil-in-water (W/O/W) emulsions containing palm oil (oil phase) was investigated. Monodisperse W/O/W emulsions prepared by primary ultrasonic emulsification using polyglycerin polycondensed ricinoleic acid ester as an oil-soluble emulsifier followed by secondary microchannel emulsification contained multiple sodium caseinate-stabilized droplets with a mean diameter of 44 μm. The multiple droplets containing palm oil maintained their diameter at 60 °C for a minimum of 24 h, whereas significant aggregation of the multiple droplets, with a partially crystallized palm oil phase, was observed below its crystallization temperature (∼27 °C). The formation of a chitosan-sodium caseinate complex layer by the electrostatic interaction of positively charged chitosan with negatively charged sodium caseinate at the oil–water interface could suppress the aggregation of the multiple droplets, even below the crystallization temperature of palm oil. Calcein, a water-soluble fluorescent dye, was stably encapsulated for a month with a high entrapment yield at 25 °C with a chitosan-sodium caseinate complex layer, although without the complex layer, it leaked to the external water phase within a day. The W/O/W emulsion with the polyelectrolyte complex layer improved both the droplet dispersibility and encapsulation efficiency of the multiple droplets during heating at 80 °C, followed by cooling at 25 °C. Polarized microscopic observations indicated that the chitosan-sodium caseinate complex layer affected the crystallization of palm oil in multiple droplets: partial crystallization of palm oil in the multiple droplets may be delayed by the presence of the polyelectrolyte complex layer at the oil–water interface.

BIFLUOROPHORES BASED ON NAPHTHALIC ACID DERIVATIVES AS BIOLOGICALLY ACTIVE SUBSTANCES

A large number of organic compounds, capable to luminesce under influence of various types of radiation, are known nowadays. These substances are called luminophores. Features of the chemical structure of these compounds determine their luminescent properties and behavior of a specific luminophore molecules in one or another environment. Possessing a number of spectral properties, luminophores are widely used in many spheres of human a ctivity. Their usage in biology and medicine plays an important role. Number of new methods of biological research, developed on the basis of luminescent dyes, is growing very quickly. This explains the need for synthesis of new luminescent dyes. Bright and water-soluble fluorescent dyes, for example, are important for sensitive detection of DNA via fluorescent probes. Currently, search for new potential antiviral agents is divided in two main strategies. One trend concerns synthesis of new derivatives of already existing antiviral drugs; chemical synthesis of such compounds is aimed at creating a new, more effective drug. Another trend in work on new antiviral drugs is the search for natural compounds, mainly of plant origin, in order to obtain potential chemotherapeutic agents. An interesting object of synthesis is formazans -- a class of organic substances with various biological activities.Biological and industrial application of formazans begins with their use as analytical reagents and dyes, and ends, primarily interesting for us, with their usage in pharmacology. They found wide practical usage as dyes, indicators of redox reactions, etc. In medicine, formazans are used due to their antioxidant, antiviral, antimicrobial, analgesic, anthelmintic and other properties. Many formazans are used in medicine as indicators of cancer cells, drugs against tuberculosis, influenza, and fungal diseases. Important advantage in of formazans synthesis is fairly easy and cheap methods of their production, available starting materials and speed of synthesis processes. In addition, an interesting direction in search for effective substances is the synthesis of formazans with luminescent properties, which significantly expand areas of their application. In our case, such organic luminophores are formazanonaphthalimides and formazanoacenaphthenquinones, which are close to them in structure.

Transcutaneous sentinel lymph node detection in cutaneous melanoma with indocyanine green and near-infrared fluorescence: A diagnostic sensitivity study.

Sentinel lymph node (SLN) biopsy with preoperative radiocolloid-based lymphoscintigraphy and blue dye injection is considered the standard procedure for staging nodal metastases in early-stage cutaneous melanoma patients with clinically uninvolved lymph nodes. While this combination renders good accuracy in SLN detection, radiation exposure and the frequent allergic reactions to the blue dye are considered drawbacks of this technique. Indocyanine green (ICG) is a water-soluble fluorescent dye that can be identified through near-infrared fluorescence imaging (NIRFI). The aim of this prospective diagnostic sensitivity study was to assess the feasibility of ICG and NIRFI to identify SLNs in melanoma transcutaneously ("before skin incision") and to analyze the various factors influencing detection rate, in comparison to lymphoscintigraphy. This study included 93 patients undergoing SLN biopsy for cutaneous melanoma. The region and the number of the SLNs identified with lymphoscintigraphy and with ICG were recorded. Patients' characteristics, as well as tumor details were also recorded preoperatively. One hundred and ninety-four SLNs were identified through lymphoscintigraphy. The sensitivity of ICG for transcutaneous identification of the location of the SLNs was 96.1% overall, while the sensitivity rate for the number of SLNs was 79.4%. Gender and age did not seem to influence detection rate, but a body mass index >30 kg/m2 was associated with a lower identification rate of the number of SLNs (P = .045). Transcutaneous identification of SLNs through ICG and NIRFI technology is a feasible technique that could potentially replace in selected patients the standard SLN detection methodology in cutaneous melanoma.

A study on multifunctional protein fibre with UV protection, moth repellency and antibacterial properties using ESIPT core containing benzimidazole and benzothiazole based functional acid azo dyes

Water soluble fluorescent acid azo dyes with benzimidazole and benzothiazole component having excited state intramolecular proton transfer (ESIPT) core were synthesised by diazo coupling. The structure of the dyes were analysed and confirmed by Fourier Transform Infrared – spectroscopy (FT-IR), elemental analysis, 1H NMR and 13C NMR analysis. Absorption and emission characteristics of the dyes were studied in different polarity solvents shown bathochromic (red) shift as solvent polarity increases. Wool and silk fabric dyed with synthesised dyes displayed high exhaustion, uniform dyeing and good wet fastness properties. The dyed substrate showed green and purple fluorescence under UV light (366 ​nm) along with UV protection. Dyed wool fabric was also assessed for antibacterial activity by calculation of bacterial reduction Staphylococcus Auerus (Gram positive), Klebsiella Pneumonia (Gram negative) bacteria. The dyed wool were also examined for the resistivity against insect pests Anthrenus Flavipies (Le Conte) by calculation of the fabric weight loss, Mortality of moth and visible assessment of fabric attacked by moth after 14 days in given conditions. Consequently, it was demonstrated that wool fabric dyed with Benzimidazole and benzothiazole based acid dyes had various functionalities, such as UV protection, antibacterial activity and mild moth repellency.

Micellar effect of CTAB on Phenol red sodium salt: A model system may be used for cell membrane study

This communication reports the effect of micelles on the molecular organisation of an anionic fluorescent dye Phenol Red Sodium salt (PRSS) in Langmuir-Blodgett (LB) film. PRSS is a water soluble anionic fluorescent dye generally used as a pH marker for cell tissue culture. Below and Above CMC of CTAB the spectral characteristics.Of PRSS molecules changes which confirms the interactions of the PRSS molecules with micelles of the CTAB. UV–vis absorption and fluorescence spectroscopic studies confirm this. So we can modified the spectral behavior of the PRSS molecules in solution as well as in LB films which may be useful as an indicator in different biological process.

The effect of a polycarboxylate ether on C3A / CaSO4·2H2O passivation monitored by optical spectroscopy

Polycarboxylate ethers (PCEs) are widely used in construction, but the exact nature of their interaction with cement is still debated. Aiming at a better understanding of the role of tricalcium aluminate (C3A) in cement hydration, we assessed the potential of optical spectroscopy in combination with a water-soluble fluorescent organic reporter dye (S0586) to monitor the early hydration of C3A in the presence of 26 wt% CaSO4·2H2O (C3A26G-S) with and without PCE. As optical methods, steady-state fluorescence and diffuse reflectance (UV–VisDR) spectroscopy were employed. Phase characterization and particle size distribution were performed with in-situ X-ray diffraction (in-situ XRD) and dynamic light scattering (DLS). Our results show that fluorescence and UV–VisDR spectroscopy can be used to monitor the formation of metastable phases by the disaggregation of the dye S0586 in a cement paste as well as changes in ettringite formation. Addition of PCE slowed down the disaggregation of the dye as reflected by the corresponding changes of the dyes absorption and fluorescence. This prolonged induction period is a well-known side effect of PCEs and agrees with previous reported calorimetric studies and the inhibition of gypsum dissolution observed by in-situ XRD. This demonstrates that fluorescence and UV–VisDR spectroscopy together with a suitable optical probe can provide deeper insights into the influence of PCE on C3A-gypsum hydration which could be e.g., utilized as screening method for comparing the influences of different types of PCEs.

Rational design of in situ localization solid-state fluorescence probe for bio-imaging of intracellular endogenous cysteine

Fluorescence detection technology has been widely concerned for its advantages of low cost, simple operation, good sensitivity, real-time and non-destructive biological imaging. However, most fluorophores emit bright fluorescence in solution, and the fluorescence decreases significantly in the high concentration or solid/aggregated state, which is called aggregation-caused quenching (ACQ). Cysteine (Cys) is an important kind of amino-acid in the field of bio-medicine, whose main function is to participate in metabolism and protein synthesis, detoxification, but intracellular cysteine concentrations (30–200 μM) are much low, and direct detection of endogenous cysteine is hampered by interference with other thiols. To solve the above problems, based on solid-state fluorophore HPQ, we for the first time prepared a novel solid-state fluorescence probe MA-HPQ, for monitoring of endogenous Cys, operated by the mechanism of excited intramolecular proton transfer (ESIPT). MeO-HPQ is completely insoluble in water, has very strong solid-state fluorescence with the maximum emission wavelength of 510 nm and the maximum excitation wavelength of 365 nm. This special property makes it very suitable for confocal microscopy compared with ordinary water-soluble fluorescent dyes. Due to the large Stokes shift (145 nm), MA-HPQ has very desirable advantages: reduced interference of background fluorescence, increased sensitivity, and enhanced contrast of biological imaging. More importantly, by preventing it from establishing internal hydrogen bonds, which is between imine nitrogen and phenolic hydroxyl groups, it can be made insoluble in water and have strong fluorescence properties, and the process is reversible. The ESIPT process can be blocked by masking phenolic hydroxyl, which can inhibit fluorescence to a large extent. In the presence of Cys, the probe reacts, releasing free MeO-HPQ, and begins to form a precipitated solid. The precipitated solid emitted bright green solid-state fluorescence, which was enhanced 43 times more than MA-HPQ. These results indicate that the probe MA-HPQ can be suitable to real spatiotemporal imaging of endogenous cysteine in HeLa cells. The excellent performance of the probe makes it applying for the visualization detection of endogenous cysteine in living cells and tissues with obtaining satisfactory results.

Dual function of Eosin Y in miniemulsion polymerization: Stabilizer and FRET acceptor

Recent studies have shown that water-soluble fluorescent dyes can be used as miniemulsion stabilizers to avoid a series of deficiencies in traditional stabilizers. However, visual means to demonstrate the stabilizing performance of water-soluble dyes are still scarce. In this study, the principle of fluorescence resonance energy transfer (FRET) is combined with dual emission of fluorescent polystyrene nanoparticles prepared by miniemulsion polymerization. For this purpose, 4-(1,2,2-triphenylethyl) phenylundecene-10-enoate (TPE-Aly) was employed as aggregation induced emission (AIE) dye and donor and Eosin Y as acceptor and stabilizer. The polymer molecular weight, particle size and size distribution of the nanoparticles were optimized by regulating the amount of Eosin Y and ultrasonication time, respectively. The average number of Eosin Y molecules per nanoparticle was firstly estimated by combining dialysis and Lambert-Beer law. FRET between TPE-Aly and Eosin Y indicates the presence of Eosin Y on the surface of the polymer nanoparticles. With increasing concentration of Eosin Y, the as-prepared dual-emission nanoparticles display a decreasing particle size along with an enhancing FRET efficiency. Moreover, various stability tests show that Eosin Y can be used as an excellent stabilizer for miniemulsion polymerization and has broad application prospects in the field of functional materials research.

Pyrene-BODIPY-substituted novel water-soluble cyclotriphosphazenes: synthesis, characterization, and photophysical properties.

In the present work, pyrene-boron-dipyrromethene (BODIPY)-substituted novel water-soluble cyclotriphosphazene derivatives (6 and 7) were synthesized by click reactions between a cyclotriphosphazene derivative with a hydrophilic glycol side group (2) and BODIPYs (4 and 5). All of the new compounds (2, 6, and 7) were characterized by Fourier-transform infrared and nuclear magnetic resonance spectroscopy, as well as mass spectrometry and elemental analysis. The photophysical properties of the BODIPY-substituted cyclotriphosphazenes (6 and 7) were investigated by UV-Vis and fluorescence emission spectroscopy in water and water/solvent mixtures. It was found that the target compounds were soluble in water and could be potential candidates as water-soluble fluorescent dyes for the desired applications.

An innovative cell imaging by beet root extracted pigment.

Fluorescent dyes are of immense interest due to their nontrivial applications in cell imaging to observe different micro organelles and their functions. We have discovered organic Beet-root extracted water soluble fluorescent (BREWSF) dye as an efficient pigment for effective cell imaging. The extraction of this pigment from beet root and its preservation is very easy and cost effective. The BREWSF dye is characterized by IR, UV-Vis, NMR, mass, fluorescence spectroscopy and flowcytometry. By applying this dye on different types of human cells we obtained very good results in fluorescence microscopy, flowcytometry and confocal cell imaging. We also have noticed that this dye takes very less internalization time to produce very good fluorescence image and flowcytometry results of cells and also remains stable at different pH levels.

Cell Architecture of the Giant Sulfur Bacterium Achromatium oxaliferum: Extra-cytoplasmic Localization of Calcium Carbonate Bodies.

ABSTRACT Achromatium oxaliferum is a large sulfur bacterium easily recognized by large intracellular calcium carbonate bodies. Although these bodies often fill major parts of the cells’ volume, their role and specific intracellular location are unclear. In this study, we used various microscopy and staining techniques to identify the cell compartment harboring the calcium carbonate bodies. We observed that Achromatium cells often lost their calcium carbonate bodies, either naturally or induced by treatments with diluted acids, ethanol, sodium bicarbonate and UV radiation which did not visibly affect the overall shape and motility of the cells (except for UV radiation). The water-soluble fluorescent dye fluorescein easily diffused into empty cavities remaining after calcium carbonate loss. Membranes (stained with Nile Red) formed a network stretching throughout the cell and surrounding empty or filled calcium carbonate cavities. The cytoplasm (stained with FITC and SYBR Green for nucleic acids) appeared highly condensed and showed spots of dissolved Ca2+ (stained with Fura-2). From our observations, we conclude that the calcium carbonate bodies are located in the periplasm, in extra-cytoplasmic pockets of the cytoplasmic membrane and are thus kept separate from the cell's cytoplasm. This periplasmic localization of the carbonate bodies might explain their dynamic formation and release upon environmental changes.

Dendronized fluorosurfactant for highly stable water-in-fluorinated oil emulsions with minimal inter-droplet transfer of small molecules

Fluorosurfactant-stabilized microfluidic droplets are widely used as pico- to nanoliter volume reactors in chemistry and biology. However, current surfactants cannot completely prevent inter-droplet transfer of small organic molecules encapsulated or produced inside the droplets. In addition, the microdroplets typically coalesce at temperatures higher than 80 °C. Therefore, the use of droplet-based platforms for ultrahigh-throughput combination drug screening and polymerase chain reaction (PCR)-based rare mutation detection has been limited. Here, we provide insights into designing surfactants that form robust microdroplets with improved stability and resistance to inter-droplet transfer. We used a panel of dendritic oligo-glycerol-based surfactants to demonstrate that a high degree of inter- and intramolecular hydrogen bonding, as well as the dendritic architecture, contribute to high droplet stability in PCR thermal cycling and minimize inter-droplet transfer of the water-soluble fluorescent dye sodium fluorescein salt and the drug doxycycline.

Self-assembling supramolecular polymer membranes for highly effective filtration of water-soluble fluorescent dyes

A new supramolecular membrane can effectively filter the water-soluble dye rhodamine 6G, resulting in high fluorescence performance and improved color stability.

Introducing a nested phase change agent with an acoustic response that depends on electric field: A candidate for myocardial perfusion imaging and drug delivery

We present a voltage-sensitive phase change agent comprising an aqueous emulsion of surfactant-coated liquid perfluorocarbon droplets nested within a negatively charged phospholipid bilayer. The sensitivity to voltage allows, via exposure to an electric field, acoustic activation of the perfluorocarbon droplets at an ultrasound intensity that is otherwise insufficient to cause activation. The result is a phase change agent for which activation depends not on ultrasound intensity but rather on the presence of an electric field. Accordingly, we offer the first enhanced ultrasound contrast agent (“Electrast”) that takes advantage of the electrical activity of the heart and leads to selective activation at a fixed mechanical index (MI). Being voltage-sensitive, Electrast activates selectively in the coronary circulation, giving enhanced ultrasound contrast within the myocardium while leaving other regions largely unenhanced. Specifically, in a closed chest swine study, the contrast enhancement between the myocardium and the left ventricle increased by 36.4 dB ±0.2 upon injection of a charged, nested PCA formulation at a fixed MI of 0.9 (GE Vivid i). Similar enhancement was observed in rats, and the contrast-to-tissue ratio increased by nearly 10 dB at an MI of 0.28 upon exposure to an electric field of 1 V/cm in a tissue-mimicking phantom. Additionally, ultrasound-induced leakage of calcein, a water-soluble fluorescent dye, from a nested, charged PCA formulation more than doubled at a peak negative pressure of 0.5 MPa upon exposure to an electric field of 0.25 V/cm. These results suggest that Electrast, a voltage-sensitive phase change agent, is a candidate for myocardial perfusion imaging using ultrasound.

New organic–inorganic hybrid polymers as Pickering emulsion stabilizers

Novel polyphosphazene (PZS) microspheres with a unique organic–inorganic hybrid cyclomatrix structure are used as stabilizers for the preparation of Pickering emulsions droplets. Both water-in-oil (W/O) and oil-in-water (O/W) polyphosphazene Pickering emulsions can be fabricated. Size control of the droplets was conducted by varying the concentration of PZS microspheres. The mean diameter of the W/O emulsion droplets varied from 150 to 400 μm at PZS microspheres loadings of between 3.3 and 20 mg/mL at φwater = 0.091. In contrast, the mean diameter of the O/W emulsion droplets varied from 60 to 100 μm at PZS microspheres loadings of between 0.25 and 1.5 mg/mL at φoil = 0.091. The types of the emulsions were determined by using oil-soluble and water-soluble fluorescent dyes to label the oil and water phases, respectively. The influence of particle surface modifications on Pickering emulsion formation was investigated by attaching fluorescent organic dyes or inorganic Fe3O4 nanoparticles to the PZS microspheres. PZS microspheres with surface-attached organic dyes formed large and unstable W/O droplets whilst surface modification with inorganic magnetic Fe3O4 nanoparticles produced stable O/W droplets. Furthermore, colloidosomes were prepared by cross-linking W/O PZS Pickering emulsions.