Dye Absorption Research Articles

To Evaluate and Compare the Microleakage of Chitosan Nano Hydrogel-Incorporated MTA and Glass Ionomer Cements When used as a Retrograde Filling Material

ABSTRACT Background: An inadequate apical seal stands out as a primary cause of disappointment in surgical endodontic procedures. Therefore, the choice of root-end filling material should aim to prevent the leakage of potential contaminants into the periapical tissue. Aim: To evaluate and compare microleakage of chitosan nano hydrogel-incorporated mineral trioxide aggregate (MTA) and glass ionomer cement (GIC) when used as a retrograde filling material. Materials and Methods: Sixty single-rooted premolars were decoronated at cemento enamel junction (CEJ), and root canals were prepared and obturated, with the coronal part sealed with a composite. The dye absorption was measured by an automatic spectrophotometer. Results: The results showed that the MTA + chitosan group had less microleakage values compared to the MTA group but was not statistically significant and GIC + chitosan had less microleakage values compared to the GIC group and was statistically significant. Conclusion: Chitosan-incorporated MTA and chitosan-incorporated GIC can be considered as retrograde filling material; however, further in vitro and in vivo research and long-term clinical studies are required.

Tracking a Homeopathic Complex Formulation in the Watercourses of a Fire-Damaged State Park in Brazil.

In 2020, a 26,849-ha state park in Mato Grosso do Sul state, Brazil, had 30% of its area damaged by fire. A homeopathic complex formulation was applied at strategic point locations in the park's springs or watercourses, aiming to mitigate the fire damage to the flora and fauna as quickly as possible. The duration of the homeopathic signal at each point was assessed using an established solvatochromic dye technique. To evaluate the timing and the nature of the signal at each of nine point locations. We could thus identify the presence of any signal variations due to specified environmental features within the park. Water samples were harvested from each intervention point at different times, filtered, frozen, and sent to the laboratory, where they were prepared to 1cH using filtered 30% ethanol. Methylene violet was chosen among six dyes since it was found in preliminary tests that it could trace the homeopathic complex used. In addition to simple sample testing, samples were submitted to a static and unidirectional magnetic field of 2400 Gauss (240 mT) for 15 minutes immediately before reading, which enhanced the method's sensitivity. One-way analysis of variance/Tukey test was used to identify dye absorbance changes following the analysis of water samples from the watercourse system. A correlation matrix and the Spearman r test were employed to evaluate any correlation between tracking and the pre-existing anthropic interventions at harvesting points. In all cases, α = 0.05. Four tracking patterns using the sample magnetization process were observed in relation to water samples and their effect on methylene violet solutions: no response (P2, P4), early transitory response (P5, P6, P8), late response (P1, P9), and constant response (P3, P7). P2 and P4, which could not be tracked, were correlated with permanent local anthropic disturbance. Methylene violet was the best dye to track the homeopathic complex prepared specifically for this case. Tracking was facilitated by prior magnetic treatment of samples, but anthropic disturbances to the environment seem to interfere with it.

Statistics of protein electrostatics.

Molecular dynamics simulations of a small redox-active protein plastocyanin address two questions. (i) Do protein electrostatics equilibrate to the Gibbsian ensemble? (ii) Do the electrostatic potential and electric field inside proteins follow the Gaussian distribution? The statistics of electrostatic potential and electric field are probed by applying small charge and dipole perturbations to different sites within the protein. Nonergodic (non-Gibbsian) sampling is detectable through violations of exact statistical rules constraining the first and second statistical moments (fluctuation-dissipation relations) and the linear relation between free-energy surfaces of the collective coordinate representing the Hamiltonian electrostatic perturbation. We find weakly nonergodic statistics of the electrostatic potential (simulation time of 0.4-1.0 μs) and non-Gibbsian and non-Gaussian statistics of the electric field. A small dipolar perturbation of the protein results in structural instabilities of the protein-water interface and multi-modal distributions of the Hamiltonian energy gap. The variance of the electrostatic potential passes through a crossover at the glass transition temperature Ttr ≃ 170 K. The dipolar susceptibility, reflecting the variance of the electric field inside the protein, strongly increases, with lowering temperature, followed by a sharp drop at Ttr. The linear relation between free-energy surfaces can be directly tested by combining absorption and emission spectra of optical dyes. It was found that the statistics of the electrostatic potential perturbation are nearly Gibbsian/Gaussian, with little deviations from the prescribed statistical rules. On the contrary, the (nonergodic) statistics of dipolar perturbations are strongly non-Gibbsian/non-Gaussian due to structural instabilities of the protein hydration shell.

Biocompatible PVAc-g-PLLA Acrylate Polymers for DLP 3D Printing with Tunable Mechanical Properties.

The technological advancement of Additive Manufacturing has enabled the fabrication of various customized artifacts and devices, which has prompted a huge demand for multimaterials that can cater to stringent mechanical, chemical, and other functional property requirements. Photocurable formulations that are widely used for Digital Light Processing (DLP)/Stereolithography (SLA) 3D printing applications are now expected to meet these new challenges of hard and soft or stretchable structural requirements in addition to good resolution in multiple scales. Here we present a biocompatible photocurable resin formulation with tunable mechanical properties that can produce hard or stretchable elastomeric 3D printed materials in a graded manner. Acrylate poly(lactic acid) (PLA) grafted polyvinyl acetate (PVAc) polymer was mixed with hydroxyl ethyl methacrylate (HEMA) and hydroxyl ethyl acrylate (HEA) as reactive diluents (50-70 wt %) in various compositions to form a series of photocurable resin formulations. Depending on the nature of the reactive diluent (HEMA or HEA) and their weight percentage, the mechanical properties of the 3D printed parts could be fine-tuned from hard (Tensile strength 20.6 ± 2 MPa, elongation 2 ± 1%) to soft (Tensile strength 1.1 ± 0.2 MPa, elongation 62 ± 8%) materials. The printed materials displayed remarkable dye absorption (95%), showing stimuli-responsive behavior for dye release (with respect to both pH and enzyme), while also demonstrating high cell viability (>90%) for mouse embryonic (WT-MEF) cells and degradability in PBS solution. These biobased 3D printing resins have the potential for a variety of applications, including tissue engineering, soft robotics, dye absorption, and elastomeric actuators.

Efficient Energy Transfer from Quantum Dots to Closely‐Bound Dye Molecules without Spectral Overlap

Quantum dots (QDs) are semiconductor nanocrystals whose optical properties can be tuned by altering their size. By combining QDs with dyes we can make hybrid QD‐dye systems exhibiting energy transfer (ET) between QDs and dyes, which is important in sensing and lighting applications. In conventional QDs that need a shell to passivate surface defects, ET usually proceeds through Förster resonance energy transfer (FRET) that requires significant spectral overlap between QD emission and dye absorbance, as well as large oscillator strengths of those transitions. This considerably limits the choice of dyes. In contrast, perovskite QDs do not require passivating shells for bright emission, which makes ET mechanisms beyond FRET accessible. This work explores the design of a CsPbBr3 QD‐dye system to achieve efficient ET from CsPbBr3 QDs to dyes with dimethyl iminium binding groups where the close binding of dyes surface facilitates spatial wavefunction overlap. Using steady‐state and time‐resolved photoluminescence experiments, we demonstrate that efficient ET from CsPbBr3 to dyes with minimal spectral overlap proceeds via the Dexter exchange‐type mechanism, which overcomes the conventional restriction of spectral overlap that severely limits the tunability of these systems. This approach opens new avenues for QD‐molecule hybrids for a wide range of applications.

Efficient Energy Transfer from Quantum Dots to Closely-Bound Dye Molecules without Spectral Overlap.

Quantum dots (QDs) are semiconductor nanocrystals whose optical properties can be tuned by altering their size. By combining QDs with dyes we can make hybrid QD-dye systems exhibiting energy transfer (ET) between QDs and dyes, which is important in sensing and lighting applications. In conventional QDs that need a shell to passivate surface defects, ET usually proceeds through Förster resonance energy transfer (FRET) that requires significant spectral overlap between QD emission and dye absorbance, as well as large oscillator strengths of those transitions. This considerably limits the choice of dyes. In contrast, perovskite QDs do not require passivating shells for bright emission, which makes ET mechanisms beyond FRET accessible. This work explores the design of a CsPbBr3 QD-dye system to achieve efficient ET from CsPbBr3 QDs to dyes with dimethyl iminium binding groups where the close binding of dyes surface facilitates spatial wavefunction overlap. Using steady-state and time-resolved photoluminescence experiments, we demonstrate that efficient ET from CsPbBr3 to dyes with minimal spectral overlap proceeds via the Dexter exchange-type mechanism, which overcomes the conventional restriction of spectral overlap that severely limits the tunability of these systems. This approach opens new avenues for QD-molecule hybrids for a wide range of applications.

Computational chemistry facilitates the development of second near-infrared xanthene-based dyes.

The dyes in the second near-infrared (NIR-II) region play a crucial role in advancing imaging technology. However, developing small-molecule dyes in NIR-II poses a significant bottleneck to meet the substantial demands in biological fields, which may be attributed to the lack of a rational design strategy. Herein, we designed a series of rhodamine analogs with more red-shifted emission by replacing the oxygen-bridge atom in xanthene-based dyes with -C(CH3)2, -Si(CH3)2, -SO2, and -P(O)Ph. We investigated the frontier molecular orbital, electrostatic potential surfaces, the interaction region indicator, electron-hole distribution, and absorption and emission spectrum of xanthene-based dyes using (time-dependent) density functional theory. Our results demonstrated that these designed small molecular dyes exhibit long emission wavelengths covering 1377-1809nm. We expected these findings to enable the targeted design of long-wavelength rhodamines. Geometry optimization of dyes in the ground and excited states was carried out at ω-B97XD/Def2SVP level using Gaussian 16 A03. The absorption and emission wavelengths were evaluated using 13 functional, including TPSSH, O3LYP, B3LYP*, B3LYP, PBE0, MPW1B95, PBE-1/3, PBE38, MPWB1K, MN15, BHandHLYP, ω-B97XD, and CAM-B3LYP.

Impact of non-linear radiation on magneto - Casson fluid suspended hybrid nanomaterials in sodium alginate: Smarter textiles

BackgroundThe combination of sodium alginate (SA) and nanoparticles in Casson nanofluids can have several advantages in textile applications such as to enhance the dye absorption and finishing properties and uniform and controlled coatings on complex shapes of the fabric and garments with intricate designs or three-dimensional textile structures etc. These fascinating properties attracted us to work on this article, a Casson hybrid nanoflow under the influence of magnetic effects past a curved stretching surface. Key terms & problem definitionThis study examines the heat transfer characteristics of Casson nanofluid flow over a stretching sheet with nonlinear thermal radiation and convective boundary conditions. A Casson fluid is a non-Newtonian fluid that exhibits a yield stress, meaning it behaves like a solid below a certain shear stress. Nonlinear thermal radiation accounts for the effects of temperature-dependent radiative heat transfer. Convective boundary conditions simulate the heat exchange between the fluid and a surrounding environment. The nanoflow has its base fluid as Sodium Alginate (SA) and a mixture of Silver (Ag) and Titanium oxide (TiO2) is suspended in the fluid. MethodologyThe nanoflow model is cracked numerically employing Runge-Kutta Fehlberg technique along with shooting method. Results of flow affecting parameters on the flow characteristic quantities and engineering quantities are portrayed and presented through graphs and tables. Key findingsHybrid Nanoflow momentum decreases with an increase in the Casson parameter due to the yield stress which quite helps in the controlled and complex shape printing on the garments. The temperature of the nanofluid increases with an increase in nonlinear radiation parameter. In the presence of Ag and TiO2 nanoparticles, the non-linear radiation parameter becomes essential for managing their intricate impact on heat transfer within the fabric. Practical relevanceImproved heat transfer can significantly reduce drying times, leading to increased productivity. More efficient heat transfer can reduce energy consumption. Reduced viscosity can allow for better penetration of fluids into fabrics, leading to more uniform dyeing and finishing. Casson hybrid nanofluids can accelerate the dyeing process and improve colour uniformity. Casson hybrid nanofluids can be used in finishing processes to enhance wrinkle resistance and improve fabric appearance.

Pyrene‐Functionalized Silicon Hybrid Porous Polymer for an Efficient Adsorption of Dyes

AbstractPyrene‐functionalized silicon hybrid porous polymer (TAPPy‐HPP). The hybrid polymer was successfully prepared via a Schiff base reaction using tetra(4‐aminophenyl)pyrene (TAPPy) and tetra(4‐formylphenyl)silane (TFS) as the building blocks.. This hybrid polymer was characterized using IR, solid‐state 13C and 29Si NMR, and elemental analysis. Its morphology was analyzed by PXRD and SEM. Thermal analysis using Thermal analysis using TGA shows that the synthetic polymer has greater thermal stability than its monomers at a temperature of 5 % weight loss (Td5 %) of 392 °C. Although TAPPy‐HPP has a Brunauer‐Emmet‐Teller surface area of 45.4 m2 g−1, it adsorbed dyes with high efficiency, particularly the anionic dye Congo Red (CR), with an adsorption capacity of up to 358 m2 g−1. Moreover, TAPPy‐HPP showed excellent recycling and regenerative properties. This polymer is a promising candidate for a fluorescent chemical sensor for the absorption of dyes due to its exceptional physiochemical stability and intense luminescence.

Study of Solvent Dependent on Third-Order Nonlinear Optical and Thermo-Optic Coefficient of Malachite Green Dye.

This study reveals the solvent dependent third-order nonlinear optical (NLO) features of malachite green (MG) dye using Z-scan technique. MG dye is dissolved in polar solvents, including DMF, DMSO, ethanol, acetone, methanol, and 1-propanol. The study employs the Z-scan instrument, using a continuous wave (CW) laser as the excitation source, operating at a wavelength of 650nm. The closed aperture (CA) and open aperture (OA) Z-scan techniques are used to assess the nonlinear indices of refraction (n2) and nonlinear coefficient of absorption (β) of MG dye. MG dye demonstrates both saturable absorption (SA) and reverse saturable absorption (RSA) in the OA Z-scan results, due to negative and positive NLO absorption coefficients. MG dye proves a self-defocusing NLO refractive index while operating under low-power conditions. The third-order NLO susceptibility (χ3) of MG dye in various liquids are calculated to be the order of 10-6 esu. Multilinear regression fit is applied here to investigate the various intermolecular interactions between the solute and solvent. MG dye exhibited large thermo-optic coefficient of the order of 10- 3 K- 1 is observed. The results give important new information about the characteristics of MG dye and indicate potential sources of material for NLO applications in future.

Spectroscopic and Computational Investigations of Azo‐Hydrazone Tautomeric Forms of Diethylamino Phenol‐Based Mono‐azo Molecules and Their In Vitro Biological Evaluations

AbstractThe present work illustrates the synthesis of some new mono‐azo dyes, which include different amines such as 2‐amino thiazole, 2‐amino‐5‐methyl‐1,3,4‐thiadiazole, and 2‐amino‐5‐methyl thiazole with 3‐diethylamino phenol as a common coupling component. The prepared azo moieties were structurally confirmed by spectroscopic techniques like NMR (1H and 13C), FT‐IR, UV –absorption, and emission properties, and HR‐MS spectrometry. Significant variations in the absorption and emission wavelengths of the azo dyes were shown by the solvatochromic behavior, which also provided an important insight into the formation of azo and hydrazone tautomeric forms. The density functional theory of the dyes was carried out to know the HOMO‐LUMO energy gaps, molecular electrostatic potential, and reduced density gradient. Further, they were screened for their in vitro antibacterial and antioxidant activities, and the results showed that the compounds exhibited excellent potentialities against various strains.

Cotton Fabric Coating by Cationic Starches to Aim for Salt‐Free Reactive Dyeing

AbstractCationic starch (CatS) coating of cellulose fabrics enables salt‐free reactive dyeing. However, the relation of the degree of substitution and CatS concentration in the dyeing procedure are open issues. Accordingly, three cationic starches of increasing degree of substitution were used at different concentrations for the coating of cotton fabrics. Fabrics were evaluated for stiffness, dye uptake, dye exhaustion, wash fastness and nitrogen content.With an increasing degree of substitution coating solutions become more viscous, resulting in increased wet pick‐up and less stiff coated fabrics. These fabrics show increasing dye absorption and color generation. Due to the molecular size of the cationic starch, yarn/fiber ring dyeing is supposed present. Specifically, color generation can be adjusted by initial cationic starch coating concentration. Above 5 % CatS concentration ceases to have an increasing coloration effect. Pre‐treating a cellulose fabric with approximately 2.2 % CatS (Ds=0.7) enables similar coloration to a standard reactive dyeing protocol. Light fastness is reduced by 1–1.5 compared to salt‐based reactive dyeing. Rub fastness decreases by 1–2 only for higher substituted cationic starches (Ds=0.7). Nitrogen analysis reveals that a share of the CatS elutes off the fabrics into the dye bath.

A Wireless‐Driven Electric Responsive Long‐Lived Room Temperature Phosphorescent Switching Device

AbstractLong‐lived room temperature phosphorescent (RTP) materials have prospective applications, but endowing long‐lived RTP materials with on‐off regulation property is challenging. Here, the first electric responsive long‐lived RTP switching device under photoexcitation with a wireless power transmission (WPT) system is demonstrated. It exhibits long persistent phosphorescence (180.1 ms for the film and 180.8 ms for the device) and excellent reversibility (>1000 cycles). Due to the effective dual‐state Förster resonance energy transfer (FRET) process from the triplet and singlet states of the chromophore donor to the singlet state of the dye acceptor, the devices exhibit switching characteristics. The appearance of the dye's absorption can be modulated by electro‐acid based on proton‐coupled electron transfer (PCET) mechanism, resulting in the device being electrically controlled. In addition, by integrating WPT coils outside the device, it can be driven wirelessly, thereby overcoming the reliance on electrical stimulation methods on the power supply. Finally, due to the multiple switching characteristics (color, fluorescence, phosphorescence) of this device, it is successfully applied in anti‐counterfeiting and information encryption.

Dye-Sensitized Solar Cells Characterization of Kitolod Leaves (Hippobroma longifora)

Energy from fossil fuels is decreasing day by day and also causes many environmental problems. In the current era, many environmentally friendly renewable energy sources have been developed, such as the development of DSSC (Dye Sensitized Solar Cells). DSSC is a technology that utilizes colored materials sourced from nature which are used as absorbers of sunlight energy to be converted into electrical energy. In this research, the synthesis and characterization of organic material from kitolod leaves as DSSC will be carried out. Kitolod leaves (Hippobroma longifora) are wild plants that usually grow in home gardens and rice fields. Kitolod leaves which have chlorophyll can support the absorption of sunlight if applied as a sensitizer in DSSC. The methods that will be used in this research are making TiO2 paste, dye solution preparation, electrolyte solution preparation, DSSC fabrication, testing and characterization. The tests that will be carried out are testing the TiO2 layer, dye absorption, and electric current. Meanwhile, the characterization that will be carried out is dye absorption using UV-Vis, and electric current using a potentiometer. From the results of light absorption shows that when the wavelength is 500 nm or the green light spectrum, the maximum light absorption by the chlorophyll of kitolod leaves is 1.78 (a.u.). The maximum voltage (Vm) and maximum current (Im) in daylight lamps have greater values ​​compared to warm white lamps. The highest efficiency of the solar light source is shown when the air mass is 1.5 (08.30-08.40). The time of DSSC immersion in dye also influences the resulting of Vm and Im values ​​which can be shown in that the Vm and Im values ​​of DSSC 2 (30 minutes) are greater than those of DSSC 1 (10 minutes). The results of open circuit voltage (Voc) and the short circuit current (Isc) in this research still need to be improved to produce better efficiency.

Enhanced Colorimetric Detection of Volatile Organic Compounds Using a Dye-Incorporated Photonic Crystal-Based Sensor Array.

Chemoresponsive dyes offer the potential to selectively detect volatile organic compounds (VOCs) unique to certain disease states. Among different VOC sensing techniques, colorimetric sensing offers the advantage of facile recognition. However, it is often challenging to discern the color changes by the naked eye. Here, highly sensitive colorimetric VOC sensor arrays from dye-incorporated colloidal photonic crystals (dye-cPhCs) are reported. cPhCs are scalably fabricated on a 4-inch wafer by spin-coating of silica nanoparticles (NPs) dispersed in a photo-cross-linkable monomer, where the gradient shear flow along the film thickness creates densely-packed square arrays of NPs in the top layers, whereas the bulk is quasi-amorphous with larger periodicities. The broadened reflection peak allows for augmented dye absorption originating from the overlap between the photonic bandgap edge of the cPhC and the dye absorption peak, leading to a more noticeable color change upon exposure to VOCs. The sensor array generates distinct color difference maps for acetaldehyde, acetone, and acetic acid, respectively, without any data amplification. The limit of detection for acetaldehyde, acetone, and acetic acid is 1, 0.1, and 0.02ppm, respectively. Moreover, VOC can be diagonalized by visually intuitive pattern recognition, and principal component analysis at reduced dimensionality is demonstrated.

Solvatochromic Dyes Track a Homeopathic Preparation through Water-Stream Systems in a Program to Control Tick Infestation at a Wild Animal Rehabilitation Center in Brazil.

In 2021, the area of CRAS (Centro de Reabilitação de Animais Selvagens - Wild Animal Rehabilitation Center), located in a state park in Campo Grande City, Mato Grosso do Sul, Brazil, was suffering from a tick infestation affecting wild animals that inhabit the area and humans that visited its trails. Following a formal technical-scientific cooperation agreement between IMASUL, an institute for the environment in Mato Grosso do Sul state, and SIGO Homeopatia, a formulated homeopathic complex (Formula Parques Urbanos, FPU) was designed and prepared specifically to treat the animals. This environmental intervention used specially designed slow-release water biodegradable devices. Tracking the FPU signal in water was necessary to monitor and manage the intervention. Our aims were (1) to evaluate, among six previously standardized solvatochromic dyes, which would serve as a marker for the homeopathic complex under study; and (2) to evaluate whether the chosen solvatochromic dye could map the propagation of the homeopathic complex activity throughout the stream system from water samples harvested at different locations over time. Water samples were harvested from each point at different times, filtered, frozen, and sent to the laboratory, where they were prepared at 1cH potency for analysis using 30% ethanol as the vehicle. Solvatochromic dyes were used to analyze the samples since they alter their absorbance when in contact with homeopathic potencies. Of the six dyes tested, Coumarin 7 was found to be the most suitable for tracking the FPU complex. A static and average unidirectional magnetic field of 2,400 Gauss (240 mT), generated by a neodymium magnet, was applied to the samples immediately before reading. There were significant differences in the delta absorbance of dyes when adding treated/potentized water samples, making it possible to map the propagation of the FPU signal throughout the park over time. The signals were identifiable at the same point 1 minute and 32 days after the insertion of the device into the water. These signals were also identifiable after 75 minutes and 8 days at a point far from the insertion place. Coumarin 7 was the best marker for the homeopathic complex (FPU) used to treat the wild animals living in the park. The microplates/enzyme-linked immunosorbent assay reader method and the application of a magnetic field to samples were shown to be effective in tracing homeopathic signals by changes in dye absorbance (p ≤ 0.02) in a real-life situation, with large volumes of water, involving many environmental variables, and over large distances.

Red‐Light Triggered H‐Abstraction Photoinitiators for the Efficient Oxygen‐Independent Therapy of Hypoxic Tumors

AbstractThe clinical application of photodynamic therapy (PDT) is limited by oxygen‐dependence and side effects caused by photosensitizer residues. Photoinitiators based on the H‐abstraction reaction can address these challenges because they can generate alkyl radical‐killing cells independently of oxygen and undergo rapid bleaching following H‐abstraction. Nonetheless, the development of photoinitiators for PDT has been impeded by the absence of effective design strategies. Herein, we have developed aryl‐ketone substituted cyanine (ACy−R), the first red‐light triggered H‐abstraction photoinitiators for hypoxic cancer therapy. These ACy−R molecules inherited the near‐infrared absorption of cyanine dye, and aryl‐ketone modification imparted H‐abstraction capability. Experimental and quantum calculations revealed that modifying the electron‐withdrawing groups of the aryl (e.g., ACy‐5F) improved the contribution of the O atom to the photon excitation process promoting intersystem crossing and H‐abstraction ability. Particularly, ACy‐5F rapidly penetrated cells and enriched in the endoplasmic reticulum. Even under severe hypoxia, ACy‐5F initiated red‐light induced H‐abstraction with intracellular biomolecules, inducing necroptosis and ferroptosis. Moreover, ACy‐5F was degraded after H‐abstraction, thus avoiding the side effects of long‐term phototoxicity after therapy. This study not only provides a crucial molecular tool for hypoxic tumors therapy, but also presents a promising strategy for the development of multifunctional photosensitizers and photoinitiators.

Red-Light Triggered H-Abstraction Photoinitiators for the Efficient Oxygen-Independent Therapy of Hypoxic Tumors.

The clinical application of photodynamic therapy (PDT) is limited by oxygen-dependence and side effects caused by photosensitizer residues. Photoinitiators based on the H-abstraction reaction can address these challenges because they can generate alkyl radical-killing cells independently of oxygen and undergo rapid bleaching following H-abstraction. Nonetheless, the development of photoinitiators for PDT has been impeded by the absence of effective design strategies. Herein, we have developed aryl-ketone substituted cyanine (ACy-R), the first red-light triggered H-abstraction photoinitiators for hypoxic cancer therapy. These ACy-R molecules inherited the near-infrared absorption of cyanine dye, and aryl-ketone modification imparted H-abstraction capability. Experimental and quantum calculations revealed that modifying the electron-withdrawing groups of the aryl (e.g., ACy-5F) improved the contribution of the O atom to the photon excitation process promoting intersystem crossing and H-abstraction ability. Particularly, ACy-5F rapidly penetrated cells and enriched in the endoplasmic reticulum. Even under severe hypoxia, ACy-5F initiated red-light induced H-abstraction with intracellular biomolecules, inducing necroptosis and ferroptosis. Moreover, ACy-5F was degraded after H-abstraction, thus avoiding the side effects of long-term phototoxicity after therapy. This study not only provides a crucial molecular tool for hypoxic tumors therapy, but also presents a promising strategy for the development of multifunctional photosensitizers and photoinitiators.

A multifunctional coating with switchable wettability for efficient oil-water and emulsions separation

Superwettable materials with switchable wettability have been attracting tremendous attention in the field of oil-water separation. In this work, a multifunctional coating with switchable wettability was designed for efficient oil-water and emulsions separation. Fe3O4 was combined with TiO2 nanoparticles and hydrophobically modified by low surface energy stearic acid (SA) to form the Fe3O4/TiO2@SA coating with uniform micro-nanostructures. The introduction or removal of amino group via ammonia treatment or heating treatment endowed the coating with reversible conversion between hydrophilicity and hydrophobicity. By switching hydrophilicity and hydrophobicity, the coating could separate oil/water/oil ternary mixtures in sequence with high separation efficiency of more than 99.9 %. More importantly, it displayed excellent separation efficiency with oil rejection above 99.5 % for oil-in-water (O/W) emulsions and water rejection above 98.7 % for water-in-oil (W/O) emulsions. Moreover, this coating showed reliable reusability and mechanical stability after 10 cycles of O/W and W/O emulsions separation and 20 cycles of sandpaper abrasion. Fe3O4 and TiO2 imparted magnetic and photocatalytic properties to the coating, allowing it to be used for magnetic navigation of oil absorption and photocatalytic degradation of organic dyes. The unique features of multifunctional coating with switchable wettability provide the blueprint for treating oily wastewater and marine oil spills.

Narrow Range of Coagulation of Ion Associates of Poly(styrene sulfonate) with Alcian Blue Dye.

The ionic association of Alcian Blue dye with poly(styrene sulfonate) in aqueous solutions was studied for analytical purposes. The quadruple-charged cationic dye, Alcian Blue, was found to form colloidal ionic associates with poly(styrene sulfonate) anions. When the amounts of opposite charges are nearly equal, the resulting ionic associates lose solubility and coagulate rapidly. This effect occurs within a narrow range of the ratio of poly(styrene sulfonate) to Alcian Blue. At the point of charge equivalence, the zeta potential of the resulting particles is zero, which facilitates flocculation. The resulting flocs enlarge to approximately 0.05-0.5 mm and precipitate rapidly. FTIR spectroscopy confirms that the precipitate contains both poly(styrene sulfonate) and Alcian Blue dye. Sedimentation kinetics was studied in detail using scanning turbidimetry. Due to the high molar absorbance of the Alcian Blue dye at 600 nm, the point of equimolar charge ratio was precisely determined by spectrophotometry. The complete precipitation of ionic associates occurs when the amount of poly(styrene sulfonate) ranges from 1.4 to 1.55 mmol per 1 g of Alcian Blue dye. Such a narrow coagulation range allows for the use of the studied effect for quantitative analysis. Both Alcian Blue dye and poly(styrene sulfonate) can be quantified if one of their concentrations is known.