Single Dye Research Articles

External Heavy-Atom Activated Phosphorescence of Organic Luminophores in a Rigid Fluid Matrix

Growing attention has been paid to pure organic room-temperature phosphorescence (RTP). Although an insufficient population and fast nonradiative decay of triplet excitons are avoided in recent endeavors, complicated synthesis and limited universality still hinder its development. Further, fluid RTP materials are more difficult to design because of faster nonradiative relaxation. Herein, a deep eutectic mixture of glucose and choline, a stable supercooled liquid at room temperature, is employed as a matrix. Direct transformation from commercial fluorescent dyes to RTP fluid is realized by doping without modifications. The excited triplet states are generated by an external heavy atom, while the rigid noncovalent network stabilizes them with both functions intrinsic to the liquid matrix. Modulation of matrix components also results in nearly white light emission of a single dye. This study presents a general strategy to design fluid RTP materials starting from the vast library of fluorophores.

Comparative Performances of Natural Dyes Extracted from Mentha Leaves, Helianthus Annuus Leaves, and Fragaria Fruit for Dye-Sensitized Solar Cells

During the last four centuries, there have been extensive research activities looking for green and clean sources of energy instead of traditional (fossil) energy in order to reduce the accumulation of gases and environmental pollution. Natural dye-sensitized solar cells (DSSCs) are one of the most promising types of photovoltaic cells for generating clean energy at a low cost. In this study, DSSCs were collected and experimentally tested using four different dyes extracted from Mentha leaves, Helianthus annuus leaves, Fragaria, and a mixture of the above extracts in equal proportions as natural stimuli for TiO2 films. The result show that solar energy was successfully turned into electricity. Additionally, DSSCs based on mixtures of dyes showed better results than those based on single dyes. Efficiency (η) was 0.714%, and the fill factor (FF) was 83.3% for the cell area.

Highly efficient harvesting of vibration energy for complex wastewater purification using Bi5Ti3FeO15 with controlled oxygen vacancies

Piezocatalyst with high and stable efficiency for multiple pollutants degradation shows great promise for practical applications but remains a challenge. Herein, a self-modified oxygen-deficient piezoelectric Bi5Ti3FeO15 catalyst is synthesized via a facile method, which demonstrates outstanding piezocatalytic properties. Investigations reveal that an optimal concentration of oxygen vacancies could increase carrier concentration, reduce the electronic impedance and enhance carrier’s separation efficiency under ultrasonic vibration, leading to superior piezocatalytic performance. As a result, the typical pollutants acid orange 7, methyl orange, rhodamine B and methylene blue dyes can be efficiently degraded by 98, 95, 94 and 94 %, respectively, within 30 and 50 min (for the latter three dyes), and the acquired degradation efficiencies are higher than most of the previously reported piezocatalysts. Moreover, Bi5Ti3FeO15 displayed excellent degradation efficiency for mixed dyes solution with a high first-order rate constant k (0.072 min−1), which is higher than most of the reported piezocatalysts for just single dye degradation. In addition, the Bi5Ti3FeO15 catalyst possesses superior environmental adaptability and highly efficient degradation ability for real textile wastewater. This work provides a novel and comprehensive strategy for designing high performance oxygen-deficient piezocatalysts that can be further extended to other Bi-based oxides, and also demonstrates that Bi5Ti3FeO15 is a promising eco-friendly and superior piezocatalyst for complex wastewater purification by harvesting mechanical energy.

Simultaneous Multiplexed Quantification of Banned Sudan Dyes Using Surface Enhanced Raman Scattering and Chemometrics.

Azo compounds such as the Sudan dyes I–IV are frequently used illegally as colorants and added to a wide range of foods. These compounds have been linked to a number of food safety hazards. Several methods have been proposed to detect food contamination by azo compounds and most of these are laboratory based; however, the development of reliable and portable methods for the detection and quantification of food contaminated by these chemicals in low concentration is still needed due to their potentially carcinogenic properties. In this study, we investigated the ability of surface enhanced Raman scattering (SERS) combined with chemometrics to quantify Sudan I–IV dyes. SERS spectra were acquired using a portable Raman device and gold nanoparticles were employed as the SERS substrate. As these dyes are hydrophobic, they were first dissolved in water: acetonitrile (1:10, v/v) as single Sudan dyes (I–IV) at varying concentrations. SERS was performed at 785 nm and the spectra were analyzed by using partial least squares regression (PLS-R) with double cross-validations. The coefficient of determination (Q2) were 0.9286, 0.9206, 0.8676 and 0.9705 for Sudan I to IV, respectively; the corresponding limits of detection (LOD) for these dyes were estimated to be 6.27 × 10−6, 5.35 × 10−5, 9.40 × 10−6 and 1.84 × 10−6 M. Next, quadruplex mixtures were made containing all four Sudan dyes. As the number of possible combinations needed to cover the full concentration range at 5% intervals would have meant collecting SERS spectra from 194,481 samples (214 combinations) we used a sustainable solution based on Latin hypercubic sampling and reduced the number of mixtures to be analyzed to just 90. After collecting SERS spectra from these mixture PLS-R models with bootstrapping validations were employed. The results were slightly worse in which the Q2 for Sudan I to IV were 0.8593, 0.7255, 0.5207 and 0.5940 when PLS1 models (i.e., one model for one dye) was employed and they changed to 0.8329, 0.7288, 0.5032 and 0.5459 when PLS2 models were employed (i.e., four dyes were modelled simultaneously). These results showed the potential of SERS to be used as a high-throughput, low-cost, and reliable methods for detecting and quantifying multiple Sudan dyes in low concentration from illegally adulterated samples.

Evidence of exciton-libron coupling in chirally adsorbed single molecules

Interplay between motion of nuclei and excitations has an important role in molecular photophysics of natural and artificial structures. Here we provide a detailed analysis of coupling between quantized librational modes (librons) and charged excited states (trions) on single phthalocyanine dyes adsorbed on a surface. By means of tip-induced electroluminescence performed with a scanning probe microscope, we identify libronic signatures in spectra of chirally adsorbed phthalocyanines and find that these signatures are absent from spectra of symmetrically adsorbed species. We create a model of the libronic coupling based on the Franck-Condon principle to simulate the spectral features. Experimentally measured librational spectra match very well the theoretically calculated librational eigenenergies and peak intensities (Franck-Condon factors). Moreover, the comparison reveals an unexpected depopulation channel for the zero libron of the excited state that can be effectively controlled by tuning the size of the nanocavity. Our results showcase the possibility of characterizing the dynamics of molecules by their low-energy molecular modes using µeV-resolved tip-enhanced spectroscopy.

Insights into the decolorization of mono and diazo dyes in single and binary dyes containing wastewater and electricity generation in up-flow constructed wetland coupled microbial fuel cell.

The treatment of single and binary azo dyes, as well as the effect of the circuit connection, aeration, and plant on the performance of UFCW-MFC, were explored in this study. The decolorization efficiency of Remazol Yellow FG (RY) (single dye: 98.2 %; binary dye: 92.3 %) was higher than Reactive Black 5 (RB5) (single: 92.3 %; binary: 86.7 %), which could be due to monoazo dye (RY) requiring fewer electrons to break the azo bond compared to the diazo dye (RB5). In contrast, the higher decolorization rate of RB5 in binary dye indicated the removal rate was affected by the electron-withdrawing groups in the dye structure. The closed circuit enhanced about 2% of color and 4% of COD removal. Aeration improved the COD removal by 6%, which could be contributed by the mineralization of intermediates. The toxicity of azo dyes was reduced by 11-26% and the degradation pathways were proposed. The dye removal by the plants was increased with a higher contact time. RB5 was more favorable to be uptook by the plant as RB5 holds a higher partial positive charge. 127.39 (RY), 125.82 (RB5), and 58.66 mW/m3 (binary) of maximum power density were generated. The lower power production in treating the binary dye could be due to more electrons being utilized for the degradation of higher dye concentration. Overall, the UFCW-MFC operated in a closed circuit, aerated, and planted conditions achieved the optimum performance in treating binary azo dyes containing wastewater (dye: 87-92%; COD: 91%) compared to the other conditions (dye: 83-92%; COD: 78-87%).

Suppressed charge recombination aided co-sensitization in dye-sensitized solar cells-based natural plant extracts

The pigments extracted from striga hermontheca, boungainvillea and momordice charantia labeled SH, BG and MC, respectively and their mixed dyes at 1:1 by volume labeled SH:MC, BG:MC and BG:SH were successfully deployed as sensitizers in fabrication of nature-based dye sensitized solar cells (DSSCs). The morphology of TiO2 as the photo anode was studied using scanning electron microscopy (SEM). The absorption, functional group, photovoltaic parameters, electrochemical impedance spectroscopy (EIS) and stability of the dye pigments and cells were studied using UV-Vis spectrophotometer, FTIR spectrometer, Keithley source meter equipped with solar simulator (2400 series), potentiostat and environmental chamber, respectively. A more positive interaction is expected as the derived dyes come from three different natural sources because they work mutually in nature. Co-sensitization of dyes showed synergistic activity with improved cell performance of 12–24-fold higher than that sensitized with any of the single dye. The cells based on mixed dyes retained ca. 18 %, 15 % and 36 % for SH:MC, BG:MC and BG:SH, respectively at 60℃ for 30 min compared with the DSSCs-based single dyes which suffered more severe degradation. Also, EIS measurements show all the cell based on mixed dyes have longer electron lifetime τnthan the cells based on single dyes. Likewise, electron collection efficiency ηcc values of the cells based on mixed dye are higher than the cells based on the single dyes. Among the cells-based mixed dyes, BG:SH has the longest τn and highest ηcc values of 18.16 ms and 0.64, respectively, which suggest better suppression of recombination for efficiency enhancement.

Fluorogenic Dimers as Bright Switchable Probes for Enhanced Super-Resolution Imaging of Cell Membranes.

Super-resolution fluorescence imaging based on single-molecule localization microscopy (SMLM) enables visualizing cellular structures with nanometric precision. However, its spatial and temporal resolution largely relies on the brightness of ON/OFF switchable fluorescent dyes. Moreover, in cell plasma membranes, the single-molecule localization is hampered by the fast lateral diffusion of membrane probes. Here, to address these two fundamental problems, we propose a concept of ON/OFF switchable probes for SMLM (points accumulation for imaging in nanoscale topography, PAINT) based on fluorogenic dimers of bright cyanine dyes. In these probes, the two cyanine units connected with a linker were modified at their extremities with low-affinity membrane anchors. Being self-quenched in water due to intramolecular dye H-aggregation, they displayed light up on reversible binding to lipid membranes. The charged group in the linker further decreased the probe affinity to the lipid membranes, thus accelerating its dynamic reversible ON/OFF switching. The concept was validated on cyanines 3 and 5. SMLM of live cells revealed that the new probes provided higher brightness and ∼10-fold slower diffusion at the cell surface, compared to reference probes Nile Red and DiD, which boosted axial localization precision >3-fold down to 31 nm. The new probe allowed unprecedented observation of nanoscale fibrous protrusions on plasma membranes of live cells with 40 s time resolution, revealing their fast dynamics. Thus, going beyond the brightness limit of single switchable dyes by cooperative dequenching in fluorogenic dimers and slowing down probe diffusion in biomembranes open the route to significant enhancement of super-resolution fluorescence microscopy of live cells.

Improved sono-assisted adsorption of a binary dye mixture using bis(2-ethylhexyl) phosphate modified Amberlite XAD-2 resin and response optimization

Methylene blue (MB) and crystal violet (CV) was simultaneously adsorbed ultrasonically on bis (2-ethylhexyl) phosphate (D2EHPA) modified Amberlite XAD-2 resin. The prepared resin was characterized by FESEM, SEM with EDS, FTIR, and point of zero charge. Preliminary studies for the removal of MB and CV dye in the mixture was done by using different ratio of D2EHPA impregnated XAD-2 resin and at different pH. Central Composite Design (CCD) of response surface methodology (RSM) was used to design and optimize the removal process. The effective parameters chosen for this study were: ultrasonication time (tus: 3–15 min), adsorbent dosage (m: 0.3–1.5 g), and initial concentration of MB (Cmbin) and CV (Ccvin) dye in solution (5–25 mg L−1). At optimized condition (tus = 10.5 min, m = 1.16 g, and concentration of Cmbin = 16 mg.L−1and Ccvin = 16 mg L−1), the maximum percentage removal for MB and CV dye was 93.38% (Qt = 1.29 mg g−1) and 97.80% (Qt = 1.32 mg g−1), respectively. pH study was performed at optimized condition by varying the pH of the dye solution from 3 to 12. At optimized condition, kinetic and equilibrium studies were performed. For single dye adsorption study, Freundlich model and for binary dye adsorption study extended Freundlich model was best fitted. The pseudo-second-order model best fitted the kinetic data for both the dyes with R2 = 0.998 for MB dye and R2 = 0.999 for CV dye which indicated the chemisorption nature of adsorbent. The possible interaction mechanism between D2EHPA and MB/CV dye was proposed. The continuous study was performed by varying flow rates using a recirculating flow vessel and found to be 12.5% more energy efficient than the batch mode. Regeneration of the adsorbent was done successfully using ethanol-water solution up to five cycles.

Simultaneous imaging of NO and NH in an ammonia-hydrogen-nitrogen flame using a single dye laser

This study describes a technique that utilizes a single, tunable, pulsed dye laser and two intensified CCD cameras to image NH and NO simultaneously in turbulent ammonia-hydrogen-nitrogen jet flames. The NO radical is excited at 236.214 nm in its (0,1) band, while NH is excited in its A3Π-X3Σ–(1,0) band using the residual energy of the beam at 303.545 nm, necessary to yield 236.214 nm via mixing with the fundamental of the pump laser at 1064.ßnm. Data show that it is possible to image the instantaneous structure of these turbulent flames, specifically, NH delineates the reaction zone while NO also marks the location of burnt products.

Effective single and contest carcinogenic dyes adsorption onto A-zeolite/bacterial cellulose composite membrane: Adsorption isotherms, kinetics, and thermodynamics

This study reports loading of A-zeolite particles on the bacterial cellulose membrane for single and binary carcinogenic dye uptake from the aqueous solution. The bio based membrane was obtained using Gluconobacter Oxydans NRRL 759 in liquid culture medium. Meanwhile, the incorporation of zeolite particles within the bacterial cellulose matrix and on its surface was implemented via in-situ synthesis. The crystallite structure and the morphology of obtained composite membrane were characterized with X-ray diffraction (XRD) and scanning electron microscopy (SEM) hyphenated with energy dispersive X-ray (EDX). The surface characteristics were intensively investigated by N2 adsorption/desorption isotherm, SBET, pore size distribution, and zeta potential. The results indicate that the treatment of bacterial cellulose with zeolite particles reflected two folds in surface area and three folds in the point of zero charge (pHzpc 6.7) compared with un-modified one. The produced composite membrane was also examined against removal of sole cationic methylene blue "MB", and anionic Congo-Red "CR" or in binary solutions included "MB" with Malachite green "MG" or "CR" with different percentages through batch adsorption technique. Different parameters affecting the adsorption process, such as dye concentration, adsorbent type, contact time, temperature, and pH, were optimized. The highest removal was recorded at optimum conditions for sole "MB" dye (99.2%), "CR" dye (81%), binary mixed "2MB/1CR" (96% after 15 min, 91% after 12 h, respectively), and "2MB/1MG" (98.6% after 30 min). Moreover, linear and nonlinear adsorption isotherm models confirmed that MB adsorption and CR obeys Freundlich isotherm model. Also, the kinetic studies revealed that the dyes' adsorption on the composite membrane could be clarified using linear and nonlinear forms of pseudo-first order, pseudo-second order, and intra-particle diffusion models. Thermodynamic findings emphasized the endothermic and spontaneous adsorption process as the adsorbent/ adsorbate physical interaction decreased the entropy. Eventually, the recyclability test revealed that the composite matrix exhibits excellent removal efficiency up to 5 recycles. The primary adsorption mechanism was proposed and confirmed with Fourier transform infrared (FTIR). Finally, the unprecedented composite membrane can be considered as an economically distinguished adsorbent for the removal of not only sol dyes but also mixtures of anionic and cationic dyes.

Thermo‐Tautochromic Polymer Architectures from Tertiary Methyl Red Amides

Thermo‐Tautochromic Polymer Architectures from Tertiary Methyl Red Amides

An experimental and theoretical investigation of cationic azine dye adsorption on natural sepiolite in single and multi-component systems

Adsorption kinetics and equilibria of the azine dyes onto natural sepiolite are investigated using Methylene Blue, Thionin and Safranin O. Experimental equilibrium results for three azine dyes are well predicted by the Freundlich, Langmuir and Redlich-Peterson isotherm models. The model parameters obtained for single solute systems at 298 K are used for the calculation of adsorption isotherms in binary and ternary dye solutions using multi-component isotherm models. Modified extended Langmuir model is satisfactorily fit to the adsorption in binary and ternary solutions. The diffuse-reflectance-infrared-Fourier-transforms technique was used to characterize the bare and dye loaded sepiolite surface. The kinetic results for single, binary and ternary dye systems have been analyzed according to the pseudo-first-order and Elovich models. Vermeulen approximation was also applied to the data for prediction of the diffusion behavior of the dyes. The molecular chemical reactivity of the dye molecules estimated based on the Density Functional Theory was well correlated to the sorption results. The energy gap between the highest-occupied molecular-orbital and lowest-unoccupied-molecular-orbital energies, chemical potential, chemical hardness, softness, global electrophilicity and global nucleophilicity values prove that Methylene Blue is more reactive than Thionine and Safranine O cationic dyes.

Front Cover: Ultra‐Bright Near‐Infrared Sulfonate‐Indolizine Cyanine‐ and Squaraine‐Albumin Chaperones: Record Quantum Yields and Applications (ChemPhotoChem 9/2022)

The Front Cover shows a single near-infrared dye being laser excited and dimly fluorescing in an aqueous biological environment compared to a near-infrared dye bound to albumin fluorescing brightly in the same environment. Cover designed by Karina Kapusta. More information can be found in the Research Article by Karina Kapusta, Jared H. Delcamp and co-workers.

Mixed dye degradation by Bacillus pseudomycoides and Acinetobacter haemolyticus isolated from industrial effluents: A combined affirmation with wetlab and in silico studies

The environment-friendly bacterial strains are used for wastewater treatment due to their high degrading capability and cost-effectiveness. In the present study, we isolated, identified, characterized, and optimized culture condition ( Temperature 35 °C for both, time up to 96 h, pH 7 and 7.5 respectively) of two dye degrading bacteria from industrial effluents. Morphological, biochemical, and molecular identification confirmed those strains as Bacillus pseudomycoides and Acinetobacter haemolyticus. Spectrophotometric methods were used to investigate the dye degradation(single and mixed dye) capability of these two bacteria. These strains were the potential for degrading methylene green (MG), basic violet (BV) and acid blue (AB) dyes. In case of MG + BV, B. pseudomycoides, and A. haemolyticus showed a degradation rate of 74% and 75%, respectively. While degradation was found 75% and 82% for MG + AB combination, 73% and 73% for AB + BV combination, and 80% and 82% for MG + BV + AB combination respectively. Azoreductase enzymes from bacteria are essential for breaking down the azo bond in textile azo dyes. In molecular docking, the binding energy of three docking complexes (protein and MG, protein and BV, protein and AB) were −6.3, −6.6, and −6.8 Kcal/mol, respectively. The binding stability of the docked complexes was ensured by the root mean square deviations (RMSD), solvent accessible surface area (SASA), radius of gyration (Rg) and hydrogen bond in a molecular dynamics simulation study, indicating strong and stable binding. This study revealed that both B. pseudomycoides and A. haemolyticus could decolorize single and mixed dyes efficiently. As a result, both the strains could be used in further research to apply their potentiality in large-scale dye degradation in the future.

Co-sintering of ceramic ultrafiltration membrane with gradient pore structures for separation of dye/salt wastewater

Robust ceramic membranes with low fabrication cost and high separation performance are particularly suitable for the separation of dye wastewater containing high salinity. In this work, a co-sintering process was employed to fabricate alumina tight ultrafiltration (UF) membranes with gradient pore structures on the alumina supports that could decrease the sintering consumption and improve the separation efficiency simultaneously. It was revealed that the phase compositions of the alumina support, alumina intermediate layer, and separation layer were all α phase, demonstrating a high acid/alkali resistance. The resulting alumina membranes produced from the co-sintering process exhibited a mean pore size of ∼5 nm and water permeance of 72 L m−1 h−1 bar−1. As a result, the membranes reject nearly 99% of dyes and allow most salts (above 99%) to pass through the membranes in treating the single dye solution, single salt solution, and mixed dye/salt solution. Finally, a concentration-diafiltration process was designed and conducted to separate and recover the saltwater and dyes from the dye/salt mixture. The results showed that Na2SO4 content in the retentate decreased from 21 g/L to 0.5 g/L while maintaining the dye concentration above 980 mg/L. This work provided a cost-effective method to prepare high-performance ceramic UF membranes for the separation of dye/salt solution.

Identification and quantification of within-burst dynamics in singly labeled single-molecule fluorescence lifetime experiments

Single-molecule spectroscopy has revolutionized molecular biophysics and provided means to probe how structural moieties within biomolecules spatially reorganize at different timescales. There are several single-molecule methodologies that probe local structural dynamics in the vicinity of a single dye-labeled residue, which rely on fluorescence lifetimes as readout. Nevertheless, an analytical framework to quantify dynamics in such single-molecule single dye fluorescence bursts, at timescales of microseconds to milliseconds, has not yet been demonstrated. Here, we suggest an analytical framework for identifying and quantifying within-burst lifetime-based dynamics, such as conformational dynamics recorded in single-molecule photo-isomerization-related fluorescence enhancement. After testing the capabilities of the analysis on simulations, we proceed to exhibit within-burst millisecond local structural dynamics in the unbound α-synuclein monomer. The analytical framework provided in this work paves the way for extracting a full picture of the energy landscape for the coordinate probed by fluorescence lifetime-based single-molecule measurements.

Development of universal fabric dyeing and adhesion through RF glow discharge plasma treatment

Various dyeing techniques are utilised at dyeing different types of fabrics and current study discuss the possibility of using a single dye bath for the given purpose. The current study utilised a radio frequency glow discharge plasma source maintained at near atmospheric conditions (around 200 mbar) in nitrogen and air environments to treat cotton, nylon, and polyester fabrics. Similar surface modifications produced in all three types of fabrics by OH and O radicals tailoring them more sensitive to certain dyes and glues. SEM images verified that bulk material is well protected by plasma treatment and the presence of additional surface functionalities (hydroxyl, carboxylic, and carbon-nitrogen groups) on the treated fabric surfaces were determined by FTIR and XPS analysis. The plasma-treated samples were dyed in a single dye bath using a reactive dye under atmospheric neutral conditions and a significant enhancement in fabric dyeability (cotton- 124%, nylon- 61%, polyester- 38%) was observed. PVA glue was used for fastening the fabric samples and the adhesion was analysed through tensile measurement. Well improved adhesion capabilities (148%, 95%, and 57.3% respectively for cotton, nylon, and polyester) also confirm the advantages of RF glow discharge plasma treatment for unified fabric processing.

Identifying optimized conditions for developing dewatered alum sludge-based photocatalyst to immobilize a wide range of dye contamination

In the current investigation, the removal of Levafix Fast Red CA (LFR) and Levafix Amber CA (LA) azo-dyes from aqueous media using the Fenton/adsorption processes has been carried out. The water treatment by-product, namely alum sludge (AS), was successfully collected and calcined to various temperatures, i.e., 400, 600 and 800 °C, then tested for use as a catalyst in the Fenton/adsorption processes. Fourier transform infrared (FT-IR) transmittance spectrum analysis and Transmission electron microscopy techniques (TEM) were applied to investigate the structural and morphological properties of such a catalyst. The results displayed that the calcined AS at 400 °C (AS400) showed the best photocatalytic activity under ultraviolet illumination and sunlight irradiation. The results indicated that the adsorption/Fenton’s oxidation systems are efficient for treatment and eliminating such types of reactive dyes. The oxidation reaction using Fenton’s reagent reached 99.9 and 86% removal for LFR and LA dyes, respectively. The operating conditions revealed that the reaction was maximized at the operational parameters of 1 g/L and 800 mg/L for AS400 and H2O2 at acidic pH (3.0). The process of single dyes was studied either from thermodynamic and kinetic viewpoints and the data exhibited that the reaction is followed a pseudo-second- order kinetic model and an exothermic reaction nature. The practical application of such byproduct waste used as a photocatalyst source through using natural solar radiation introduces an industrial ecology approach in treating dye effluents for safer environment.

Ultra-photostable DNA FluoroCubes: Mechanism of Photostability and Compatibility with FRET and Dark Quenching.

DNA-based FluoroCubes were recently developed as a solution to photobleaching, a ubiquitous limitation of fluorescence microscopy (Niekamp; ; Stuurman; ; Vale Nature Methods, 2020). FluoroCubes, that is, compact ∼4 × 4 × 5.4 nm3 four-helix bundles coupled to ≤6 fluorescent dyes, remain fluorescent up to ∼50× longer than single dyes and emit up to ∼40× as many photons. The current work answers two important questions about the FluoroCubes. First, what is the mechanism by which photostability is enhanced? Second, are FluoroCubes compatible with Förster resonance energy transfer (FRET) and similar techniques? We use single particle photobleaching studies to show that photostability arises through interactions between the fluorophores and the four-helix DNA bundle. Supporting this, we discover that smaller ∼4 × 4 × 2.7 nm3 FluoroCubes also confer ultraphotostability. However, we find that certain dye-dye interactions negatively impact FluoroCube performance. Accordingly, 4-dye FluoroCubes lacking these interactions perform better than 6-dye FluoroCubes. We also demonstrate that FluoroCubes are compatible with FRET and dark quenching applications.