Photostability Of Dyes Research Articles

Linked Rotaxane Structure Restricts Local Molecular Motions in Solution to Enhance Fluorescence Properties of Tetraphenylethylene.

The restriction of local molecular motions is critical for improving the fluorescence quantum yields (FQYs) and the photostability of fluorescent dyes. Herein, we report a supramolecular approach to enhance the performance of fluorescent dyes by incorporating a linked rotaxane structure with permethylated α-cyclodextrins. Tetraphenylethylene (TPE) derivatives generally exhibit low FQYs in solution due to the molecular motions in the excited state. We show that TPE with linked rotaxane structures on two sides displays up to 15-fold higher FQYs. Detailed investigations with variable temperature 1 H NMR, UV-Vis, and photoluminescence spectroscopy revealed that the linked rotaxane structure rigidifies the TPE moiety and thus suppresses the local molecular motions and non-radiative decay. Moreover, the linked rotaxane structure enhances the FQY of the dye in various solvents, including aqueous solutions, and improves the photostability through the inhibition of local molecular motions in the excited TPE.

Rational design of a large Stokes shift xanthene-benzothiozolium dyad for probing cysteine in mitochondria.

Xanthene-modified cyanine dyes are considered to be an effective means to extend the emission wavelength and improve the photo-stability of cyanine dyes. However, the fluorophores obtained by this strategy generally have narrow Stokes shifts, which severely limits their application in biological imaging. Herein, a reasonable design strategy is adopted to provide an effective strategy to commendably improve the Stokes shift of xanthene-benzothiozolium fluorophores via the simultaneous expansion of a molecular π-conjugated system and heteroatomic substitution. Combined with density functional theory calculation guidance, the O atom is replaced with the S atom in the xanthene moiety and a π-conjugated benzene ring is introduced in the benzothiozolium moiety. Surprisingly, the results of the spectroscopic experiment showed that the fluorescence emission wavelength of PhCy-OH was extended to 803 nm, and the Stokes shift was improved to 68 nm. PhCy-Cys can effectively distinguish Cys from homocysteine (Hcy) and glutathione (GSH) with an extremely low detection limit of 0.166 μM. Importantly, PhCy-Cys has the ability to image endogenous Cys in mitochondria, providing the potential for exploring the specific function and mechanism of Cys in regulating oxidative stress in mitochondria.

Enhancing Hybrid Upconversion Nanosystems via Synergistic Effects of Moiety Engineered NIR Dyes.

Hybrid upconversion nanosystems have been reported to improve the low absorption efficiency of lanthanide-doped upconversion nanoparticles (UCNPs). However, the low quantum yield and poor photostability of NIR dyes pose challenges for practical uses. Here, we introduce a bulky moiety, 4-(1,2,2-triphenylvinyl)-1,1'-biphenyl (TPEO), to enhance its quantum yield by suppressing the bond rotation and improve the stability by deactivating the photoinduced oxidization. Compared with the conventional IR806, the formed NIR dye, TPEO-Cy, has been characterized to deliver three times higher quantum yield and seven times better photostability. Moreover, we take advantage of the strong affinity of sulfonate chains on the TPEO-Cy to bind to the surface of UCNPs. Taking together the synergistic effect, we have achieved a 242-fold upconversion emission enhancement over the benchmark of IR806-sensitized system and an ∼800 000-fold increase than the bare UCNPs. Our design of the NIR dyes suggests a new scope to search for more efficient upconversion nanohybrids.

Improving the photostability of fluorescent dyes by polymer nano‐insulating layer

AbstractFluorescein is a traditional organic fluorescent dye that has the disadvantage of agglomeration‐induced fluorescence quenching and photobleaching due to its large hydrophobic conjugate π‐π system, which makes them have limitations in many fields of application. A method of polymer modification is revealed to address this issue. In this study, fluorescein molecules were modified by polycaprolactone (PCL) to obtain PCL grafting fluorescein (PxF), and subsequently assembled with PEG‐PCL to obtain fluorescent nanoparticles (PPxF). PPxF would realize long term cellular fluorescence imaging. PCL polymerization induces self‐assembly, which effectively avoids fluorescence quenching caused by fluorescent molecules aggregation, and at the same time well inhibit the energy transfer with oxygen to improve photostability. This method is a good way to improve the fluorescence properties of fluorescent dyes, to be suitable for all traditional organic fluorescent dyes to greatly improve their fluorescence and hydrophilic properties and enhance their application fields.

Flexible and directional fibre optic ultrasound transmitters using photostable dyes.

All-optical ultrasound transducers are well-suited for use in imaging during minimally invasive surgical procedures. This requires highly miniaturised and flexible devices. Here we present optical ultrasound transmitters for imaging applications based on modified optical fibre distal tips which allow for larger transmitter element sizes, whilst maintaining small diameter proximal optical fibre. Three optical ultrasound transmitter configurations were compared; a 400 µm core optical fibre, a 200 µm core optical fibre with a 400 µm core optical fibre distal tip, and a 200 µm core optical fibre with a 400 µm core capillary distal tip. All the transmitters used a polydimethylsiloxane-dye composite material for ultrasound generation. The material comprised a photostable infra-red absorbing dye to provide optical absorption for the ultrasound transduction. The generated ultrasound beam profile for the three transmitters was compared, demonstrating similar results, with lateral beam widths <1.7 mm at a depth of 10 mm. The composite material demonstrates a promising alternative to previously reported materials, generating ultrasound pressures exceeding 2 MPa, with corresponding bandwidths ca. 30 MHz. These highly flexible ultrasound transmitters can be readily incorporated into medical devices with small lateral dimensions.

Enhancement in photostability of betalain dye from basella Alba fruits using zinc oxide nanoparticles

Recently environmental pollution due to industrial effluents is a major concern for researchers, so the development of natural dyes is widely accepted due to their low cost, biodegradability, low toxicity, and non -carcinogenic nature and also replaces existing hazardous chemicals in industries. Many plants and fruit extracts can be used as natural dyes, but their efficiency depends on photostability and photo degradation activity. Herein reported extraction of natural dye fromBasella Alba fruit using different solvents and photo stability was investigated under UV and visible light. To enhance the stability of extracted pure dye, zinc oxide nanoparticles were added and it acts as an excellent photostabilizer that shows better performance over betalain dye. UV visible spectrum of pure dye shows an absorbance peak of 480 nm and functional groups of both dye and zinc oxide were identified by FTIR spectrum. The structure and surface morphology of the synthesized nanoparticle was confirmed by UV–Visible, XRD, SEM-EDAX and TEM analysis. The crystalline structure of zinc oxide was confirmed by XRD and composition was analyzed by EDAX studies. The wurtzite type structure of zinc nanoparticle was confirmed by XRD. The external morphology of prepared zinc oxide nanoparticles is captured using FESEM. The HRTEM and SAED images are confirmed the crystalline structure of the synthesized material. The photostability and photodegradation studies were performed under UV light and at various temperatures like 40 °C, 50 °C, 60 °C, 70 °C, and 80 °C. These results clearly show a piece of evidence for the usage of nanoparticles for enhancing photostability of natural dyes.

Investigating Photochromic Behavior of Organic Dyes in Solution Form using Multilevel Factorial Design

Photochromic compounds, namely spiropyran, spirooxazine, and naphthopyran, have received much attention, because of their high potential applications in various industrial fields. The aim of this study is to understand the behavior of three photochromic dyes in solution form via statistical approach. The types of dyes and solvents were screened using multilevel factorial design. From the analysis of variance results, it was found that the types of dyes and solvents used as well as their interaction have significant effects on the absorbance and photostability. The naphthopyran compound displayed highest change in absorbance intensity, followed by spiropyran and spirooxazine, when dissolved in isopropanol separately. However, the spirooxazine is the most photostable dye compared to naphthopyran and spiropyran, with ethanol as the solvent. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Cyanine Dyes for Photo-Thermal Therapy: A Comparison of Synthetic Liposomes and Natural Erythrocyte-Based Carriers

Cyanine fluorescent dyes are attractive diagnostic or therapeutic agents due to their excellent optical properties. However, in free form, their use in biological applications is limited due to the short circulation time, instability, and toxicity. Therefore, their encapsulation into nano-carriers might help overcome the above-mentioned issues. In addition to indocyanine green (ICG), which is clinically approved and therefore the most widely used fluorescent dye, we tested the structurally similar and cheaper alternative called IR-820. Both dyes were encapsulated into liposomes. However, due to the synthetic origin of liposomes, they can induce an immunogenic response. To address this challenge, we proposed to use erythrocyte membrane vesicles (EMVs) as “new era” nano-carriers for cyanine dyes. The optical properties of both dyes were investigated in different biological relevant media. Then, the temperature stability and photo-stability of dyes in free form and encapsulated into liposomes and EMVs were evaluated. Nano-carriers efficiently protected dyes from thermal degradation, as well as from photo-induced degradation. Finally, a hemotoxicity study revealed that EMVs seem less hemotoxic dye carriers than clinically approved liposomes. Herein, we showed that EMVs exhibit great potential as nano-carriers for dyes with improved stability and hemocompatibility without losing excellent optical properties.

The novel approach of stability aspect in organic oligoene dye for dye-sensitized solar cell applications

The phenyl-conjugated oligoene dye 2-cyano3-(4-diphenylaminophenyl)prop-2-enoic acid (SKS) was synthesized by chemical method, and its structure was confirmed by 1H NMR and 13C NMR analysis. Solar cell was made using TiO2 (P-25) as photoanode, synthesized oligoene SKS dye as sensitizer, I-/I3- as electrolyte, and platinum as counter electrode. The overall power conversion efficiency of SKS dye based solar cell was 1.76 %. The functional groups were identified from the FTIR spectrum. The optical, electrochemical, and thermal properties were analyzed. The photostability of SKS dye was analyzed before and after various light irradiation by UV-Vis NIR absorption spectrum.

Novel violet fluorescent nanoparticles for immunophenotyping using flow cytometry

Abstract A novel series of fluorescent nanoparticles with violet excitation have been developed for use with flow cytometry antibodies. These exceptionally bright, photostable dyes also have narrow emission spectra, making them ideal for inclusion in high parameter multicolor panels. For this study, StarBright Violets 440, 515, 610, 670, 710 and 790 were conjugated to human B-cell, T-cell, and Treg marker monoclonal antibodies and used to immunophenotype human peripheral blood mononuclear cells (PBMCs) in an 8-color panel. Tests with this panel were conducted in different staining buffers and compared to a panel with dyes having similar spectra and the same clonality. The new StarBright multicolor panel showed better resolution of Treg populations and reliable identification of the different T- and B-cell populations across different stain buffers and conditions, which makes the StarBright Violet nanoparticles an excellent addition to the field of high parameter flow cytometry.

Explorations into the Effect of meso‐Substituents in Tricarbocyanine Dyes: A Path to Diverse Biomolecular Probes and Materials

AbstractPolymethine cyanine dyes have been widely recognized as promising chemical tools for a range of life science and biomedical applications, such as fluorescent staining of DNA and proteins in gel electrophoresis, fluorescence guided surgery, or as ratiometric probes for probing biochemical pathways. The photophysical properties of such dyes can be tuned through the synthetic modification of the conjugated backbone, for example, by altering aromatic cores or by varying the length of the conjugated polymethine chain. Alternative routes to shaping the absorption, emission, and photostability of dyes of this family are centered around the chemical modifications on the polymethine chain. This Minireview aims to discuss strategies for the introduction of substituents in the meso‐position, their effect on the photophysical properties of these dyes and some structure–activity correlations which could help overcome common limitations in the state of the art in the synthesis.

Explorations into the Effect of meso-Substituents in Tricarbocyanine Dyes: A Path to Diverse Biomolecular Probes and Materials.

Polymethine cyanine dyes have been widely recognized as promising chemical tools for a range of life science and biomedical applications, such as fluorescent staining of DNA and proteins in gel electrophoresis, fluorescence guided surgery, or as ratiometric probes for probing biochemical pathways. The photophysical properties of such dyes can be tuned through the synthetic modification of the conjugated backbone, for example, by altering aromatic cores or by varying the length of the conjugated polymethine chain. Alternative routes to shaping the absorption, emission, and photostability of dyes of this family are centered around the chemical modifications on the polymethine chain. This Minireview aims to discuss strategies for the introduction of substituents in the meso‐position, their effect on the photophysical properties of these dyes and some structure–activity correlations which could help overcome common limitations in the state of the art in the synthesis.

Enhanced photostability of anthocyanin dye for increased efficiency in natural dye sensitized solar cells

To improve the performance of anthocyanin based dye sensitized solar cells (DSSC), it is essential to passivate the photocatalytic activity (PCA) induced by photoelectrode that activates dye degradation. In the present work, red color astaxanthin pigments extracted from green color Haematococcus Pluvialis is used as a cosensitizer with anthocyanins extracted from rose petals to scavenge the free radicals (antioxidant) generated as a result of PCA, thereby minimizing photodegradation of anthocyanins by 60 %. Herein we have hydrothermally prepared rutile TiO2 nanostructures that appear as distorted TiO2 nanospheres (NS) and the cosensitizer ratio is optimized for maximum astaxanthin efficacy. The least molecular interaction of astaxanthin with anthocyanins as measured from fluorescence life time studies suggest that astaxanthin encircle anthocyanins as a shield against photodegradation. The structure of DSSC with Fluorine doped Tin Oxide/TiO2 NS/algal buffer layer / cosensitized dye (Rose:Astaxanthin - 70 :30) /iodine-iodide/ Pt /glass shows a higher efficiency of 2.82 %. Relatively higher efficiency of 3.31 % was also observed for DSSC with 3% Ca doped TiO2 nanorods as photoelectrode using cosensitized dye as sensitizer due to the passivation of PCA by the astaxanthins and the photoelectrode by itself.

Enhancing Photostability of a Coumarin Dye by Self‐inclusion into a Cyclodextrin Cavity in Aqueous Solution and Living Cells

AbstractPhotostable organic dyes are highly demanded for longtime or super‐resolution bioimaging. Herein, we demonstrate effective improvement of photostability of a coumarin dye (Pacific Blue (PB)) by steric protection using a cyclodextrin. The PB conjugated cyclodextrin (PB−CD) showed 2.8 times higher photostability than PB ethyl amide (PB−EA) which is a comparative compound in vitro. The cyclodextrin conjugation to PB not only protect PB unit from reactive chemicals, but also suppress reactive oxygen species (ROS) generation which causes dye degradation. The effects afford significant improvement of photostability of PB dye. Finally, the photostability of PB−CD was evaluated using confocal laser scanning microscopy (CLSM) and the significant improvement effect was proofed even in living cells.

Studies on the photofading of alizarin, the main component of madder

Natural dyes have been the focus of textile industry for their environmental protection properties. However, some limitations such as poor photostability has limited their wide application, and the researches of the discoloration mechanism of fabric with natural dye are relatively limited. As one of the most important natural dye, madder has been widely used in textile field. Herein, as the main pigment of madder, alizarin was selected as the model natural dye to explore the photo-fading progress of alizarin-dyed fabrics. The photodegradation progress of alizarin was explored by UV, HPLC, HPLC-MS and Datacolor (computer color matching system). When exposed to light, alizarin could be oxidized into colorless small molecules through ·OH radical-mediated route, and finally resulting in the fading of alizarin. In addition, the influence of pre-mordant and the liquid rate has also been studied. These results provide us a good insight into the photo-fading progress of natural dyes, and our work could help to open the way to further studies aiming at improving the photostability of natural dyes or developing new photo-stable dyes.

Unifying Mechanism for Thiol-Induced Photoswitching and Photostability of Cyanine Dyes.

Cyanines (Cy3, Cy5, Cy3B) are the most utilized dyes for single-molecule fluorescence and localization-based super-resolution imaging. These modalities exploit cyanines' versatile photochemical behavior with thiols. A mechanism reconciling seemingly divergent results and enabling control over cyanine photoreactivity is however missing. Utilizing single-molecule fluorescence on Cy5 and Cy5B, transient-absorption spectroscopy, and DFT modeling on a range of cyanine dyes, herein we show that photoinduced electron transfer (PeT) from a thiolate to Cy in their triplet excited state and then triplet-to-singlet intersystem crossing in the nascent geminate radical pair are crucial steps. Next, a bifurcation occurs, yielding either back electron transfer and regeneration of ground state Cy, required for photostabilization, or Cy-thiol adduct formation, necessary for super-resolution microscopy. Cy regeneration via photoinduced thiol elimination is favored by adduct absorption spectra broadening. Elimination is also shown to occur through an acid-catalyzed reaction. Overall, our work provides a roadmap for designing fluorophores, photoswitching agents, and triplet excited state quenchers for single-molecule and super-resolution imaging.

Host-guest complexation of curcumin and coumarin 6 with PAMAM-OH: Insight from fluorescence spectroscopy and molecular dynamics simulations

The 1:1 host-guest association between hydroxyl-terminated poly(amido amine) dendrimers of the fourth generation (G4-PAMAM-OH) and two model fluorescent dyes, curcumin (CUR) and coumarin 6 (CU6), was studied from fluorescence intensity experiments and fully atomistic molecular dynamics (MD) simulations. Our results account for experimental binding constants of 3.45 × 105 and 2.97 × 105 mol−1L for CUR-G4-PAMAM-OH and CU6-G4-PAMAM-OH systems, respectively. The potential of dendrimer complexation to increase dye photostability was evaluated from fluorescence intensity experiments in 5–100 μmol L−1 dye solutions containing 100 μmol L−1 of G4-PAMAM-OH under visible light irradiation. Our results revealed that G4-PAMAM-OH enhances the photostability of CUR at 1:1, 1:2 and 1:20 dye-dendrimer ratios, whereas CU6 is effectively protected only at 1:20 dendrimer excess conditions. MD simulations predicted a deep encapsulation of CUR within innermost dendrimer branches and an outer association of CU6 to surface dendrimer cavities, which can be related to the enhanced photoprotection of CUR at lower dye-dendrimer ratios. MM/GBSA binding free energy estimates suggest the predominance of van der Waals interactions between apolar dye segments and hydrophobic dendrimer pockets as the main binding forces driving dye-dendrimer supramolecular association in the systems under study.

Light-Harvesting Nanoparticle Probes for FRET-Based Detection of Oligonucleotides with Single-Molecule Sensitivity.

Controlling the emission of bright luminescent nanoparticles by a single molecular recognition event remains a challenge in the design of ultrasensitive probes for biomolecules. Herein, we developed 20-nm light-harvesting nanoantenna particles, built of a tailor-made hydrophobic charged polymer poly(ethyl methacrylate-co-methacrylic acid), encapsulating circa 1000 strongly coupled and highly emissive rhodamine dyes with their bulky counterion. Being 87-fold brighter than quantum dots QDots 605 in single-particle microscopy (with 550-nm excitation), these DNA-functionalized nanoparticles exhibit over 50 % total FRET efficiency to a single hybridized FRET acceptor, a highly photostable dye (ATTO665), leading to circa 250-fold signal amplification. The obtained FRET nanoprobes enable single-molecule detection of short DNA and RNA sequences, encoding a cancer marker (survivin), and imaging single hybridization events by an epi-fluorescence microscope with ultralow excitation irradiance close to that of ambient sunlight.

Light‐Harvesting Nanoparticle Probes for FRET‐Based Detection of Oligonucleotides with Single‐Molecule Sensitivity

AbstractControlling the emission of bright luminescent nanoparticles by a single molecular recognition event remains a challenge in the design of ultrasensitive probes for biomolecules. Herein, we developed 20‐nm light‐harvesting nanoantenna particles, built of a tailor‐made hydrophobic charged polymer poly(ethyl methacrylate‐co‐methacrylic acid), encapsulating circa 1000 strongly coupled and highly emissive rhodamine dyes with their bulky counterion. Being 87‐fold brighter than quantum dots QDots 605 in single‐particle microscopy (with 550‐nm excitation), these DNA‐functionalized nanoparticles exhibit over 50 % total FRET efficiency to a single hybridized FRET acceptor, a highly photostable dye (ATTO665), leading to circa 250‐fold signal amplification. The obtained FRET nanoprobes enable single‐molecule detection of short DNA and RNA sequences, encoding a cancer marker (survivin), and imaging single hybridization events by an epi‐fluorescence microscope with ultralow excitation irradiance close to that of ambient sunlight.

Optical, photo physical parameters and photo stability of 6-Substituted-1, 2, 4-Triazine mono glucosyl derivative to act as a laser dye in various solvents.

The optical properties of a visible absorption range6-Substituted-1, 2, 4-Triazine mono glucosyl fluorescent derivative dye, such as absorption spectra, emission spectra in different solvents, were experimentally investigated. As well, some important photo physical parameters such as extinction coefficient (ε), cross-sections of the absorption (σa) and the emission (σe), quantum yield (фf), fluorescence lifetime, oscillator strength (f), the dipole moment (μ), decay rate radiative constant (kr), energy yield of fluorescence (Ef) and the length of attenuation Λ (λ) were assessed. The ground-state (μg) and excited-state (μe) dipole moments by solvatochromic correlations method were reported. The dye amplified spontaneous emission (ASE) of 2×10-4M with different input pumping energies of a continuous wave blue diode laser (λ=450nm) was studied. Photostability of dye was observed that was decreased to 53% of its initial energy by pumping with 100mW of diode laser after exposure to 120min.