Behavior Of Dyes Research Articles

Effectively controlling luminescent property and the ESIPT behavior of styryl dyes by atomic substituent

In view of the unique luminescent characteristics, excited state intramolecular proton transfer (ESIPT) materials have attracted lots of attention. Considering the influence of different atomic substituents on the photophysical properties and ESIPT reaction, we systematically studied the molecular and electronic properties of styryl dyes with O, S and Se substituents by the quantum chemistry methods. The results indicated that the ESIPT energy barrier of styryl dyes reduced with atomic substituents (O < S < Se). And potential energy curves (PECs) showed that the ultra-fast ESIPT reaction of styryl dyes could be controlled and regulated by atomic substituents. In addition, the styryl dyes had a large stokes shift, which reproduced the double fluorescence properties. It meaned that the enol and keto structures of three styryl dyes interconvert by ESIPT channel under the photoexcitation. Therefore, the special optical properties of styryl dyes could improve their application as potential biological imaging.

Thermosolvatochromic Behavior of Quinolinium and Pyridinium 4-Hydroxystyryl Dyes in Solutions

Thermosolvatochromic Behavior of Quinolinium and Pyridinium 4-Hydroxystyryl Dyes in Solutions

Adsorption kinetics, equilibrium, and thermodynamic studies to understand adsorption behavior of Evans blue dye by durian husk

Adsorption kinetics, equilibrium, and thermodynamic studies to understand adsorption behavior of Evans blue dye by durian husk

Synthesis, spectroscopic, and structural studies of substituent effect on the solvatochromic, tautomeric, and halochromic behavior of 2-methylated arylazoquinoline dyes along with DFT calculations

Six methylated heteroarylazo quinoline dyes with different electron-withdrawing/donating substituents, namely 5-(4-substituted arylazo)-8-hydroxy-2-methyl quinoline dyes, were synthesized by coupling reaction and their chemical structures were elucidated by conventional spectroscopic methods. The photophysical properties of the dyes were examined and systematically compared in a range of solvents of various solvatochromic parameters and at various pH values through UV–Vis spectroscopy. 2-methylated arylazoquinoline dye (the unsubstituted dye) was prepared and chosen for comparison purposes. The dyes show different chromic behavior including tautomerism, solvatochromism, ionochromism, and halochromism. The chromic and azo/hydrazone tautomeric properties of the dyes were found to depend on the substituent nature, solvent polarity/polarizability, and the acidity/basicity of the solvent environment. The Kamlet-Abboud-Taft, Katritzky, and Catalán linear solvation energy relationships (LSER) were used to correlate the dye spectral data. The acid-base equilibria between neutral and anionic forms of the dyes were studied in buffer solutions in a range of pH 1.0–13.0 and the ionization constants,pKa, were determined. Finally, the DFT calculations on the studied compounds provide an overall supportive and complementary picture of the spectral measurements of representative structure of the azo model.

EFFECT OF VARIOUS MORDANTS ON DYEING ABILITY OF SAFFLOWER DYE

The production and implementation of synthetic dyes generate significant waste and unfixed colorant. Which raises health risks, and pollution and disrupts eco-balance. Nature has always dominated over synthetic or artificial materials since the beginning of time because nature was the only choice for humans at the time, and now with the advantageous properties of naturally derived materials over synthetics, they have priority(Yusuf et. al., 2017). Safflower is an all-natural red dye that is frequently used to color cotton. It includes the well-known constituents reddish carthamin and yellowish safflower yellow. In the present study, the dyeing behaviour of safflower is examined by the use of an aqueous method and different mordants on linen, cotton, and silk. The relationship between the dye-uptake of linen, cotton, and silk fabric investigated with the various dyeing conditions is discussed.

Exploring solvation behaviour of biocompatible ionic liquid 2-hydroxyethylammonium formate + polyethylene glycols mixtures: Role of oxyethylene and hydroxyl units of PEGs

The favourable modification of the physicochemical properties of the ionic liquid with green co-solvent and their molecular level characterization with spectroscopic techniques is the area of current research. Further, the co-solvent modified ionic liquid mixtures furnishes interesting properties which render the utility of these solvents in several important applications. In the current work, the effects of addition of two polyethylene glycols (PEGs) with average molecular weights of 200, and 600 on solvent properties of IL 2-hydroxyethyl ammonium formate (HEF) has been explored with the help of solvatochromic absorbance probes. The physicochemical characteristics of the ionic liquid mixtures are altered in an unexpectedly positive way when PEGs are added to IL HEF. The absorbance behaviour of the solvatochromic probes Reichardt dye 33 shows interestingly positive non-ideal behaviour, which may be attributed to the high dipolarity/polarizability (π*) and hydrogen bond donor ability (HBD) (α) of the HEF + PEG mixtures. Further, the Kamlet-Taft parameters, including hydrogen bond acceptor ability (HBA) (β), and hydrogen bond donor ability (HBD) (α), and dipolarity/polarizability (π*) of the HEF + PEG binary mixtures display nonideality, which may be because of the strong Hydrogen bond networking of HEF-PEG molecules along with solute-HEF/PEG interaction present in the mixtures. Moreover, the preferential solvation approach has been invoked to explore the solute–solvent/solvent–solvent interactions present in the HEF + PEGs binary mixtures. The Redlich–Kister (CNIBS/R–K) theoretical model predicts the experimental results obtained by solvatochromic probe studies in satisfactory manner. The results of the DFT and FTIR study also predict the possibility of the H-bonding interactions in HEF + PEGs mixtures.

Investigation of the uptake and compatibility behaviors of special disperse dyes developed for sustainable color matching in supercritical carbon dioxide

The uptake and compatibility behaviors of nine developed special disperse dyes belonging to different temperature groups were investigated for the first time on polyester fabric to achieve appropriate dyes for sustainable color matching in supercritical fluid of carbon dioxide (SCF-CO2). Different temperature-rising dyeing rate curves for the special dyes were established and employed to explore their uptake behaviors, compatibilities and other performances in SCF-CO2. Furthermore, the dye uptake behaviors and coloration compatibilities were also investigated at different system temperatures, pressures and dyeing durations. Then, a practical color matching was further carried out by utilizing low-temperature group dyes as a model in SCF-CO2. The obtained results show that an overall satisfactory uptake and compatibility behaviors of the developed dyes were achieved as for sustainable color matching, which were assigned to different temperature types in SCF-CO2. The temperature-rising dyeing rate curves for high-, moderate- and low-temperature type dyes show that very similar uptake behaviors and enhancement tendencies were obtained with the increase of system temperature and duration, accompanied with good coloration performances at uptake ratio ranging from 70 % to 90 % in a large supercritical dyebath. Moreover, significant and similar effects on the uptake behaviors of an individual group dyes from the parameters were achieved, which further indicate that good color matching compatibilities and uptake behaviors for each group dyes were available at different conditions. The practical color matching as well as the monochrome coloration in SCF-CO2 shows that different target shades in gray or various neutral colors, etc., were successfully achieved with low-temperature group dyes, by exhibiting perfect leveling property, high color fastness, which fully met industrial requirements in quality and environmentally friendly characteristics with water free.

Electrochemical behaviour of anthraquinone dyes in non-aqueous solvent solution. Part II. Controlled potential electrolysis of alizarin

This article is the second part of our already published research results (Caram, Banera, Martínez Suárez, Mirífico, 2017). The present work aims to characterise/identify reaction intermediates and final products of the cathodic electrolysis of alizarin (AH2) in solution of DMF and ACN with TBAP and NaClO4 as supporting electrolytes to corroborate the reaction mechanism previously published by us. Intermediates and reaction products are accumulated by controlled potential electrolysis (CPE) of AH2 performed at the potentials of the first, second, and third charge transfers. Progress of the electrolysis is followed by CV. The techniques employed for the characterisation/identification of the involved chemical species are CV, UV–Vis, FTIR, 1H and 13C NMR, ESR, elemental analysis, and quantum chemical computations based on density functional theory (DFT). Some aspects of the mechanism are corroborated, some details are modified, and new insights are obtained. Intermediates are detected by CV, and the structure of some of them (AH2● ─, AH3●, and AH─) is confirmed by ESR and by the identity of the isolated reaction products (1-hydroxy-2-methoxyanthracene-9,10-dione (AH-CH3) by adding an excess of CH3I at the end of the CPE in DMF/TBAP and NaClO4 as the electrolyte systems, and sodium 1-hydroxy-9,10-dioxo-9,10-dihydroanthracene-2-olate (AH-Na) in ACN/NaClO4). Ion pair formation between AH2● ─ semiquinone radical anion with Na+ is significant. The homogeneous dissociation equilibrium AH3─ ⇄AH22– + H+ does not occur, and AH2• – + AH2 ⇄ AH – + AH3• is a slow process more shifted to the right in DMF/TBAP electrolyte medium. AH-CH3 and AH-Na are clear evidence of the self-protonation reaction of AH2• –. Ca. 20 % of the initial moles of AH2 are converted into AH-CH3 in DMF/TBAP and NaClO4 as the electrolyte systems. CPE of AH2 in ACN/NaClO4 results in reaction products that are insoluble and are coating the electrode, ca. 80 % of the initial moles of AH2 are recuperated as pure AH-Na. AH-CH3 and AH-Na contain the carbonyl-quinone groups in their structures. The applied potential does not modify these results. AH-CH3 and AH-Na are electrochemically (CV) characterised. The acidity of the quinone dye, the homogeneous protonation/deprotonation equilibriums, the intramolecular hydrogen bonding, and the easy air oxidation and protonation of some of the intermediates have led to the obtained results.

Environment polarity effects on the microscopic nonlinear optical properties of some asymmetrical azobenzene molecules

Solvent as a complex environment can surround solute molecules and modify their function. In this work, different solute–solvent interaction effects on the nonlinear optical behavior of some azo dyes were studied at the molecular level. In this case, spectroscopic technique and density functional theory were used. According to the results, molecular dipole transition, changes between ground and excited state dipole moments, substituent, and environment polarity play considerable effects on the molecular nonlinear optical responses. In addition to solvent effects on the molecular first- and second-order hyperpolarizability, the two-photon absorption cross-section is also modified due to solvent-induced interactions. Moreover, the determination of the contribution of dominant solvent effects on the molecular nonlinear optical behavior can facilitate the studies on the application of optical samples in designing various optical systems.

Influence of structure and functional group of modified kraft lignin on adsorption behavior of dye

Utilization of kraft lignin to produce bio-based adsorptive material for effective dye adsorption from industrial wastewater is essential to fulfilling the significant environmental protection needs. Lignin is the most abundant byproduct material with a chemical structure containing various functional groups. However, the complicated chemical structure makes it somewhat hydrophobic and incompatible, which limits its direct application as an adsorption material. Chemical modification is a common way to enhance lignin properties. In this work, the kraft lignin was modified through direct amination using Mannich reaction and oxidization followed by amination as new route of lignin modification. The prepared lignins, including aminated lignin (AL), oxidized lignin (OL), and aminated-oxidized lignin (AOL), as well as unmodified kraft lignin, were analyzed by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), elemental analysis and 1H-nuclear magnetic resonance measurements (1HNMR). The adsorption behaviors of modified lignins for the malachite green in aqueous solution were investigated well and discussed, as well as the adsorption kinetics and thermodynamic equations. Compared with other aminated lignin (AL), the AOL displayed a high adsorption capacity of 99.1 % dye removal, due to its more effective functional groups. The change in structure and functional groups on the lignin molecules during oxidation and amination had no effect on its adsorption mechanisms. The adsorption process of malachite green on different kinds of lignin belongs to endothermic chemical adsorption, which mainly consists of monolayer adsorption. The modification of lignin through oxidation followed by amination process, afforded kraft lignin a broad potential application in the field of wastewater treatment.

Functional surface homogenization of nanobiochar with cation exchanger for improved removal performance of methylene blue and lead pollutants

Biochar materials are good examples of sustainable adsorbents with appreciable recent interests and applications in water treatment. The disadvantage of using unmodified pristine biochars in water treatment is mainly related to the inhomogeneous distribution of various surface functional groups. Therefore, the current study is designed to functionalize and homogenize the surface of a selected nanobiochar with a cation exchanger using hydrothermal and solvothermal microwave irradiation. The adsorption behavior of immobilized Amberlite cation exchanger onto Cynara scolymus nanobiochar (ACE@CSNB) was compared versus the pristine Cynara scolymus nanobiochar (CSNB). ACE@CSNB was categorized as a typical mesoporous material (mean pore size = 2.238 nm) and the FT-IR spectra confirmed surface modification via two characteristic peaks at 1140–1250 cm−1 and 1030–1070 cm−1 for R-SO3− with S = O. The TPD–MS analysis of CSNB and ACE@CSNB referred to the presence of carboxyl, lactonic, and acid anhydride groups as well as phenolic moieties. The adsorption behavior of methylene blue dye and lead ions by ACE@CSNB was found much higher than those concluded by CSNB providing maximum adsorptive capacity values owing to the played clear role by Amberlite cation exchanger. Moreover, ACE@CSNB was efficiently regenerated and confirmed MB and Pb(II) removal with 92.26% and 1000 µmol g−1, respectively Finally, the removal efficiency values from three water matrices by ACE@CSNB biochar were characterized as 91.74–98.19% and 96.27–99.14% for Pb(II) and MB, respectively to refer to the validity and applicability of the investigated ACE@CSNB biochar for treatment of these two pollutants from real water samples with excellent efficiency.Graphical

Advances in Polymethine Dyes for Near‐Infrared Organic Photodiodes†

Comprehensive SummaryNear‐infrared organic photodiodes (NIR OPDs) have tremendous potential in industrial, military, and scientific applications, due to their unique features of lightweight, low toxicity, high structural flexibility, cooling‐system‐free, etc. However, the overall performance of currently available NIR OPDs still lags behind the commercial inorganic photodetectors, ascribed to the critical challenge of realizing organic semiconductors with sufficiently low optical bandgap and excellent optoelectronic properties simultaneously. Among various types of NIR‐absorbing organic semiconductors, polymethine dyes not only possess advantages of simple synthesis and structural diversity, but also show fascinating optical and aggregation features in the solid state, making them attractive material candidates for NIR OPDs. In this review, after a brief introduction of NIR OPDs and polymethine dyes, we comprehensively summarize the advances of polymethine dyes for broadband and narrowband NIR OPDs, and further introduce their applications in all‐organic optical upconversion devices and photoplethysmography sensors. In particular, the relationship between the chemical structure and the aggregation behaviors of polymethine dyes and the device performance is carefully discussed, providing some important molecular insights for developing high performance NIR OPDs.

Adsorption behavior of Crys tal Violet dye in aqueous solution using Co+2 hectorite composite as adsorbent surface

This study focused on the adsorption behavior of the cationic CrystalViolet (CV) dye from aqueous solutions using a Co+2‒hectoritecomposite as an adsorbent surface. The initial and equilibrium CV dyeconcentrations were determined using a UV-Vis spectrophotometer. Theresults were discussed and presented for the impacts of pH, primary CVdye concentration, composite dosage, and temperature. The optimumconditions were found for eliminating Crys tal Violet dye from theaqueous solution at a pH 4, ideal temperature 293 K, and 0.5 g L-1of composite dose. The pseudo-second-order kinetic, intraparticlediffusion analyzed the tes ts’ data and film diffusion models. Eachmodel’s defining features have been identified, and these models werein good agreement and in charge of regulating the adsorption reaction.The adsorption operation was also thermodynamically examined todetermine thermodynamic variables such as Gibbs free energy (ΔGo),entropy (ΔSo), activation energy (Ea), and enthalpy (ΔHo). The negativevalue of Gibbs free energy (ΔGo) and enthalpy (ΔHo) indicated thatthe adsorption process was a spontaneous and exothermic reaction.While the activation energy (Ea) data which fell within the normalrange for physisorption, was showed at 22.434 kJ mol-1. The physical adsorption occurs between CV dye and adsorbent .

Chemically synthesized manganese oxide nanorods for effectual organic dye removal and energy storage application

Manganese oxide nanoparticles (MnO2) are successfully synthesized by using a facile chemical co-precipitation and reflux-assisted co-precipitation method with varying annealing temperatures and reflux time respectively. The synthesized samples' structural, optical and thermal properties are investigated by XRD, FTIR spectra, Ultraviolet–Visible spectroscopy, Thermogravimetric Analysis and BET surface area analyzer. The average crystallite sizes assessed by Scherrer's equation (Williamson- Hall plot) of prepared samples are in the range of 6–8 nm (6–7 nm) for the reflux-assisted method and 15–30 nm (20–46 nm) for the co-precipitation method respectively. The presence of peaks associated with Mn-O bonds in FTIR spectra confirmed the formation of MnO2 nanoparticles. FESEM studies revealed the nanorod-type morphologies of samples. The prepared samples showed pseudocapacitive behaviour and significant photocatalytic degradation of brilliant green dye.

The photophysics of distorted nanographenes: Ultra-slow relaxation dynamics, memory effects, and delayed fluorescence

The controlled deformation and engineering of the sp2 carbon network in atomically-precise nanographenes, and their substantially larger size as compared to typical optical dyes, opens new opportunities for the modulation of optical and electronic properties, but the peculiar photophysics of these systems is still poorly understood. Here, through a detailed comparative study of two well-defined distorted nanographenes, we show that they can exhibit interesting photophysical features, such as triplet-triplet annihilation delayed fluorescence, ultra-slow excited state dynamics, and excitation-wavelength memory effects on the nanosecond and sub-nanosecond relaxation cascades. Some of these behaviours are highly unexpected and strongly deviate from the archetypal behaviour of typical optical dyes. The distortion of the sp2 network was obtained by means of a non-hexagonal ring and a helicene unit, introduced by taking advantage of the high control provided by specific bottom-up organic synthesis. We believe the rich conformational landscape provided by the combination of the saddle-shaped curvature due to the heptagon ring and the helicene edge is at the heart of the uncommon photophysics.

Characterization of unexpected blue-shifted single molecule fluorescence of JF646 and JF669 for SMLM.

JF-Halotag dyes have become increasingly popular for single-molecule localization microscopy (SMLM) because of their favorable photo-physics, ease of use, and compatibility with live-cell imaging. However under a variety of conditions, the excitation and emission wavelengths from individual emitters can deviate significantly from the commonly accepted characterization, leading to artifacts in two color SMLM data. Here I show results from multiple in vivo and in vitro experiments demonstrating 640nm mediated photo switching of JF669 from a conventional far-red signal to a 561nm excitable red single molecule signal. This result is exciting because it enables UV-free PALM experiments. UV radiation causes cell death, increases auto fluorescence, and induces cell stress, which may affect the behavior of labeled proteins or cellular processes of interest. Additionally, I present evidence of a subpopulation of JF646 molecules that can be excited by 561nm light, but emit red instead of far-red light. This unexpected fluorescence causes single molecule cross talk in the red channel, despite the commonly accepted characterization. This phenomenon is more apparent at low dye concentrations as well as high temperatures, suggesting that a self-interaction between JF646 molecules may bias the well characterized fluorescence, while in isolation JF646 may have significantly blue-shifted excitation and emission spectra. Together, these results show potentially useful photo-physical behavior of JF dyes, but also highlight the importance of careful controls when using synthetic dyes for single molecule localization microscopy.

Green synthesis of novel magnetite mixed metal oxides with cationic surfactant nanocomposite: Investigation of its effective removal of Azorubine E122 food dye and antimicrobial activity

Design and assembly of novel nanocomposites with multi‐purpose activities including efficient adsorption behavior toward different pollutants and microbial growth inhibition of various active biological species is a challenging aspect. Therefore, the current study is devoted to fabricating a novel nanocomposite of mixed metal oxides (ZrO2 and SiO2) with magnetite (Fe3O4) and cationic surfactants (cetyltrimethyl ammonium bromide [CTAB] and dodecyltrimethyl ammonium bromide [DoTAB]) via a solvent free microwave methodology to yield ZrSiO4 NPs‐CTAB@Fe3O4 NPs‐DoTAB. The as‐prepared nanocomposite was characterized by SEM to confirm the existence of homogeneous particles (~32.45 nm). The chemical structure of nanocomposite was also confirmed from the energy dispersive X‐ray spectroscopy (EDX), Fourier‐transform infrared spectroscopy (FTIR), and X‐ray diffraction (XRD) analyses. The surface area of this nanocomposite was also determined by the Brunauer‐ Emmett‐ Teller (BET) method and found to correspond to 6.319 m2 g−1. Remediation of Azorubine E122 food dye was optimized in the presence of a number of controlling parameters. The maximum adsorption capacity was characterized as 66.55 mg g−1 using 50 mg nanocomposite at 20 min. Kinetics and isotherm modeling evaluations referred to the best fitting with pseudo‐second order and Freundlich model, respectively. The antibacterial activity of ZrSiO4 NPs‐CTAB@Fe3O4 NPs‐DoTAB nanocomposite was assessed against Escherichia coli ATCC® 25922™ and Staphylococcus aureus ATCC® 25923™, and the collected data proved efficient growth inhibition (p &lt; 0.05) at considerably low concentrations of the investigated nanocomposite. Therefore, the evaluated ZrSiO4 NPs‐CTAB@Fe3O4 NPs‐DoTAB nanocomposite was concluded to afford excellent antibacterial activity and efficient magnetic removal behavior of organic dyes. Hence, it is recommended as a talented material for purification of water resources containing multi‐chemical and biological pollutants as well. Finally, this study is expected to open new prospects for manufacturing other new nanocomposites with the aim of future applications in the removal of different chemical pollutants as well as viruses and bacteria.

Study the Interaction Adsorptive Behavior of Sunset Yellow Dye and Loratadine Drug: Kinetics and Thermodynamics Study

The performance of drug treatment and assessments of different drugs' side effects both can be affected by the interaction between food additives and drugs. Organic compounds such as food colorants dyes are utilized as additives in a wide range of foods. In this study, the adsorption interaction behavior between the colorant food dye sunset yellow (SY) and the drug loratadine was examined. The adsorption procedure is conducted at different drug dosages, various SY dye concentrations, and different temperature (288-318K). The equilibrium data were explained by using Freundlich and Langmuir adsorption isotherms, but Langmuir offering the best fit model. Kinetics adsorptive behavior of sunset yellow on loratadine matched pseudo-second order kinetics. Thermodynamics study show that the process is exothermic, spontaneous and the disorder at the solid-solution interface was proven from the negative entropy (-140.556 J/ K.mol) of adsorption process.

Adsorption/desorption behavior of ionic dyes on sintered bone char

The aim of this study was to investigate the regularity and differences in the adsorption/desorption behavior of bovine rib char (BC) as an adsorbent material for the cationic Malachite Green (MG) and anionic Sunset Yellow (SY) dyes. The effects of pyrolysis temperature, adsorbent dosage, solution pH, initial concentration, contact time, and adsorption temperature were investigated. The pore characteristics of BC were determined by the Brunauer-Emmett-Teller (BET) method. The changes in functional groups before and after the adsorption of BC were analyzed by Fourier transform infrared spectroscopy. And the chemical composition and surface morphology of BC were characterized by X-ray diffraction and scanning electron microscopy. The experimental data were further analyzed using different isotherm models, kinetic models, and thermodynamic equations, and an understanding of the adsorption studies was carried out. The results show that BC is 90% mesoporous with a BET specific surface area of approximately 150 m2/g. BC is rich in active sites at 700 °C and performs best in the adsorption process. The adsorption of MG increases with increasing pH, while the opposite is true for SY, with optimum pH values of 7 and 3, respectively. Ionic dyes bind to BC easily (the fitted values for the Freundlich model 1/n are all less than 0.5, R2 > 0.748). The maximum adsorption capacity (Qmax) of MG was much higher than that of SY (the Langmuir model indicated Qmax of 1168.4 mg/g and 47.0 mg/g, respectively, R2 > 0.830). The adsorption of ionic dyes on BC was mainly non-homogeneous surface chemisorption, which was spontaneous (ΔG<0, ΔH>0). The desorption of BC after adsorption of MG and SY in HCl and NaOH solutions, respectively, was better. Analysis of the adsorption contribution of the BC fraction showed that the mineral fraction played an important role in the adsorption process (about 94%), while the organic fraction contributed about 6%. The experimental results indicate that the adsorption mechanism of MG and SY on BC can be attributed to the filling of mesopores, electrostatic interaction between the ionic polar sites of BC and the different charged dyes, the formation of chemical bonds between the oxygen-containing functional groups on the surface of BC and the dyes, and the ionic exchange between the polar sites of BC such as Ca2+, PO43−, CO32− and OH−.

Lipid packing is disrupted in copolymeric nanodiscs compared with intact membranes

Discoidal lipid-protein nanoparticles known as nanodiscs are widely used tools in structural and membrane biology. Amphipathic, synthetic copolymers have recently become an attractive alternative to membrane scaffold proteins for the formation of nanodiscs. Such copolymers can directly intercalate into, and form nanodiscs from, intact membranes without detergents. Although these copolymer nanodiscs can extract native membrane lipids, it remains unclear whether native membrane properties are also retained. To determine the extent to which bilayer lipid packing is retained in nanodiscs, we measured the behavior of packing-sensitive fluorescent dyes in various nanodisc preparations compared with intact lipid bilayers. We analyzed styrene-maleic acid (SMA), diisobutylene-maleic acid (DIBMA), and polymethacrylate (PMA) as nanodisc scaffolds at various copolymer-to-lipid ratios and temperatures. Measurements of Laurdan spectral shifts revealed that dimyristoyl-phosphatidylcholine (DMPC) nanodiscs had increased lipid headgroup packing compared with large unilamellar vesicles (LUVs) above the lipid melting temperature for all three copolymers. Similar effects were observed for DMPC nanodiscs stabilized by membrane scaffolding protein MSP1E1. Increased lipid headgroup packing was also observed when comparing nanodiscs with intact membranes composed of binary mixtures of 1-palmitoyl-2-oleoyl-phosphocholine (POPC) and di-palmitoyl-phosphocholine (DPPC), which show fluid-gel-phase coexistence. Similarly, Laurdan reported increased headgroup packing in nanodiscs for biomimetic mixtures containing cholesterol, most notable for relatively disordered membranes. The magnitudes of these ordering effects were not identical for the various copolymers, with SMA being the most and DIBMA being the least perturbing. Finally, nanodiscs derived from mammalian cell membranes showed similarly increased lipid headgroup packing. We conclude that nanodiscs generally do not completely retain the physical properties of intact membranes.