Search Results (101)

The use of dyes as sensitizing agents to increase semiconductor activity is a strategy already adopted in the field of heterogeneous photocatalysis, but the compounds applied are noble metal-based and sometimes difficult to synthesize, which make it more expensive. In this work, it was discovered that methylene blue can perform such an effect on an iron molybdate functionalized with peroxo groups on the surface. This material, called MoOxoFe, was tested together with its analogue MoFe (produced without H₂O₂ in the synthesis) in the degradation of methylene blue. The rapid degradation of the dye led to the hypothesis of sensitization, which was investigated and proven by additional photocatalytic tests with sensitized material, MoOxoFe-MB, and spectroscopies, such as EPR and XPS. Full article

BODIPY (Boron-Dipyrromethene) dyes have emerged as versatile fluorescent probes in cellular imaging and therapeutic applications owing to their unique chemical properties, including high fluorescence quantum yield, strong extinction coefficients, and remarkable photostability. This review synthesizes the recent advancements in BODIPY dyes, focusing on their deployment in biological imaging and therapy. The exceptional ability of BODIPY dyes to selectively stain cellular structures enables precise visualization of lipids, proteins, and nucleic acids within live and tumor cells, thereby facilitating enhanced understanding of biochemical processes. Moreover, BODIPY derivatives are increasingly utilized in Photodynamic therapy (PDT) and Photothermal therapies (PTT) for targeting cancer cells, where their capability to generate cytotoxic reactive oxygen species upon light activation offers a promising approach to tumor treatment. Recently, BODIPY derivatives have been used for Boron Neutron Capture Therapy (BNCT) for various tumors, and it is a growing research field. Advancements in nanotechnology have allowed the fabrication of BODIPY dye-based nanomedicines, either alone or with the use of metallic nanoparticles as a matrix offering the development of a new class of bioimaging and theragnostic agents. This review also discusses innovative BODIPY-based formulations and strategies that amplify therapeutic efficacy while minimizing adverse effects, underscoring the potential of these dyes as integral components in next-generation diagnostic and therapeutic modalities. By summarizing current research and future perspectives, this review highlights the critical importance of BODIPY dyes in advancing the fields of cellular imaging and treatment methodologies. Full article

This perspective sets out to raise awareness about the chemical and photophysical properties of indigo, a highly distinguished colorant with an extraordinary history. Indigo, like many other dyes, was first extracted from plants at an inordinately low yield and at great ecological expense. Such was its popularity that indigo was among the first natural colorants to be synthesized in a laboratory before refinement and cost reduction resulted in its economical industrial-scale production. The color of indigo is highly characteristic but difficult to describe, since it falls at the blue/violet interface. It is a small, planar molecule with an exceptionally high degree of π-electron conjugation that pushes the absorption maximum to above 600 nm. Its structure helps explain the high level of photostability enjoyed by indigo, while recent spectroscopic studies have added to our understanding of the longevity of this emblematic colorant. The reversible formation of leuco-indigo increases the ways in which indigo can be used to add color to objects while helping to circumvent the effects of attack by free radicals. It is stressed that the journal Colorants would welcome submissions that describe the chemistry and/or spectroscopy of other representative colorants. Full article

Dyeing is a major contributor to pollution, with high concentrations of hydrolyzed dyes and electrolytes in its effluents. Recent studies suggest the possibility of dyeing cotton substrates with reactive dyes in an oil medium, reducing the need for electrolytes. This study evaluated the dyeing of cotton yarns with reactive Red 195 dye in an oil medium using crude and refined soybean oil. The method employed 75% oil and 25% water, with the oil recovered for reuse, significantly reducing water consumption and effluent generation. Dyeing with crude soybean oil showed higher color intensity than the conventional method and the use of refined soybean oil. Additionally, reducing electrolyte concentration from 75 to 18.75 g/L did not affect color intensity, yielding similar results to conventional aqueous dyeing. The dyed substrates were tested for washing, rubbing, and lightfastness, showing comparable performance to conventional methods. The dyeing followed pseudo-second-order kinetics, and the Freundlich isotherm model better fit the oil medium process. FTIR analysis revealed no changes in the functional groups on the yarn surface, and tensile strength tests showed similar results across methods. These findings indicate that oil medium dyeing can reduce electrolyte use, conserve water, and allow for oil reuse, demonstrating potential for industrial-scale application. Full article

Textile dyes often prove resistant to conventional wastewater treatment processes because of their complex molecular structures. Advanced oxidation methods, such as the Fenton reaction, have thus been recognized as a promising approach for environmental remediation by decomposing these pollutants. This work aimed to study the efficacy of modified zeolites as catalysts in the Fenton reaction for dye degradation, with a particular emphasis on techniques for modifying zeolites and incorporating iron. The zeolite ZSM-5 was selected as the parent structure and underwent desilication and acid treatment procedures. Iron was introduced into the zeolite structure via two distinct methods: ion exchange and mechanochemistry. The modified zeolites with incorporated iron were evaluated in terms of their crystallinity, textural properties, and iron content before being used to degrade methylene blue solutions through the Fenton reaction. The reaction was monitored using UV-Vis spectroscopy, while the experimental outcomes were analyzed using pseudo-first-order and pseudo-second-order kinetic models. The research findings indicate that different treatment methods led to varying impacts on the zeolite properties, which in turn influenced the kinetic results. Moreover, it was observed that an enhancement in the degradation process can be achieved through the harmonious balance between a high iron content, increased mesoporosity (to facilitate diffusion), and adequate crystallinity (essential for maintaining structural integrity). Full article

A series of compounds with both urea and urethane moieties have been developed as color developers for high-performance thermo-sensitive paper. The compounds have lower environmental loads than conventional phenolic developers. They were also found to greatly improve the speed of the printed images. In this study, we studied the coloring mechanism of the compounds when used as developers for a fluoran dye, and we investigated the stability of the colored solid state. The urea–urethane compounds were found to form black amorphous solids with the fluoran dye. Infrared (IR) measurements of the black solids, based on six urea–urethane derivatives, revealed that the colored dye has a ring-opened structure in a carboxylic acid form and that the urea group works as a proton donor for the ring-opening reaction. The stability of the black amorphous solids was also evaluated using thermal analysis and molecular orbital calculations in addition to IR data. The results indicate that the number of urea–urethane units and the planarity of the urea moiety are important parameters for the stability of the colored solid state. Full article

The use of indigo carmine dye in the textile industry, particularly in denim production, presents a significant sustainability challenge due to the large amounts of wastewater generated by this process, since this fabric is one of the most produced around the world. In order to face challenges like this, effluent treatment using polymeric materials has become an area of intense research. In this study, we developed an eco-friendly hydrogel based on oligoglycerol-malic acid polyester crosslinked with citric acid, which was applied to adsorb indigo carmine. The properties of the hydrogel and its precursors were analyzed using spectroscopic, thermal, and morphologic techniques. The hydrogel demonstrated water uptake capacity up to 187% of its own mass and adsorbed approximately 73% of the dye after 24 h of contact. Tests were conducted in the presence of sodium chloride and indicated that the presence of salt impairs the adsorption process. Additionally, the adsorption kinetics and isotherms were evaluated and demonstrated that the adsorption followed a pseudo-second-order model, indicating a chemisorption process, and a Langmuir isotherm, consistent with a monolayer adsorption. These results emphasize the potential of this hydrogel for removing dye and its application in textile industry wastewater treatment, aiming to minimize environmental impacts. Full article

Water contamination caused by dyes from increased human activities, in particular usage in the textile sector, has led to high rates of disposal of both natural and synthetic dyes in the water stream, affecting the color and the ability of the light to penetrate through the water system. Several methods have been used for the removal of these organic pollutants. However, due to the complex nature of these dyes, researchers have geared toward advanced oxidation processes (AOPs). This method allows for the degradation of these pollutants into more environmentally friendly pollutants. Green synthesis of known catalysts has been on the rise, in particular nickel oxide (NiO) NPs. This material has been shown to have the ability to degrade several pollutants. However, due to the high recombination rate and large bandgap, their limitation has also been highlighted along with the importance of modification. Thus, it is important to understand the work and progress made on green NiO as a photocatalyst for the degradation of dyes and the latest advancements in the field. Full article

The detection of reactive dyes in food matrices is crucial for food safety and compliance with regulations, especially since the use of such in food products is not approved. This study investigates the potential of using tin(II)chloride and laccase to cleave anthraquinone reactive dyes and to detect their characteristic degradation products as markers for the presence of dye in food. Nine reactive blue anthraquinone dyes and one green anthraquinone dye were cleaved using tin(II)chloride and laccase. Reactions with reactive dyes bound to maize starch were also carried out to evaluate the suitability of these methods for detecting matrix-bound dyes. Model food matrices, including gummy candy, hard candy, and maize chips, were spiked with the reactive dyes, and the presence of degradation products was analysed using LC-ESI-MS/MS. Two common cleavage products were formed from each sample, namely 1,4-diaminoanthrahydroquinone-2-sulphonic acid (DAHS) and 1-aminoanthraquinone-2-sulphonic acid (AAS). In all examined cases, at least one of the characteristic cleavage products could be detected. Laccase showed lower effectiveness with matrix-bound dyes, whereas treatment with acidic tin(II)chloride was effective even in complex food matrices. These findings suggest that the analysis of cleavage products could be a valuable tool for the detection of reactive dyes in food matrices. Full article

Photodynamic therapy (PDT) is a light-activated chemical reaction used for the selective destruction of tissue. For this, various colorants may be applied, such as erythrosine (ERI), a dye already approved by the Food and Drug Administration (FDA) for various purposes. Although promising for PDT, ERI has a high hydrophilic profile that impacts its activity. To solve this, the combination of ERI with thermoresponsive and bioadhesive polymers may prove effective. Bio/mucoadhesive and thermoresponsive systems have attracted increasing interest in the development of novel pharmaceutical formulations for topical applications due to their ability to improve adhesion to the mucosa and prolong the residence time at the application site. In this study, systems based on poloxamer 407 (P407) in combination with cellulose derivatives (HPMC and NaCMC) were optimized, aiming at the topical release of ERI for PDT. The results demonstrated that the formulations containing low concentrations of cellulose derivatives exhibited greater adhesiveness and consistency at physiological temperature (37 °C), favoring the maintenance of the system at the application site. Regarding the gelation temperature (T_sol/gel), the formulations displayed values close to body temperature. The formulations with NaCMC showed a slightly higher T_sol/gel compared to HPMC ones, but it was adjustable by the polymer concentration. The addition of ERI influenced the mechanical and adhesive properties of the systems. In formulations containing HPMC, high concentrations of ERI increased bio/mucoadhesiveness, while in systems with NaCMC, the presence of ERI reduced this property. In both cases, the formulations maintained high consistency at 37 °C, contributing to the control of the active release at the application site. Rheological analysis revealed non-Newtonian behavior in all formulations, with greater consistency and elasticity at high temperatures. P407 was mainly responsible for the thermoresponsive transition from sol to gel, conferring desirable characteristics for topical application. Photodynamic activity was relevant in both formulations containing NaCMC and HPMC, which demonstrated greater capacity for degrading uric acid under light exposure. These systems are promising for the controlled release of drugs in photodynamic therapy, providing prolonged retention in the target tissue and maximizing the therapeutic efficacy of ERI. Full article

The effects of photochemical reactions induced by UV radiation in solutions of metal phthalocyanines were carried out to determine the factors that might influence the photostability of photosensitized phthalocyanines. Three different indium phthalocyanines, including the diindium triple-decker phthalocyanine, In₂Pc₃ (1), sandwich indium phthalocyanine, InPc₂ (2) and iodoindium phthalocyanine, InPcI (3) in benzene, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), dichloromethane (DCM) and 1-chloronaphtalene, were studied. The rate of decay of absorption is explained by a decomposition reaction that is of first-order kinetics with respect to the phthalocyanine concentration. In general, the presence of ligand I⁻ in phthalocyanine InPcI enhances the rate of decomposition. The kinetics of the degradation process proved to depend on the molecular structure of the complex and seems to be controlled by interactions of the macrocycle bridging nitrogen atoms with the solvent molecules. The indium phthalocyanines in benzene displayed the capacity for singlet oxygen generation. Full article

In this study, hybrid materials were synthesized incorporating curcumin, Cu²⁺ or Fe³⁺, and Kappa-carrageenan as a reducing agent to improve stability, considering that curcumin has low thermal and solution stability, which limits its applications. Colorimetric analysis showed color changes in the hybrids, ultraviolet–visible spectroscopy revealed band shifts in the hybrids, and infrared analysis indicated shifts in wavenumbers, suggesting changes in the vibrational state of curcumin after bonding with metal ions. These techniques confirmed the formation of hybrid materials. Thermogravimetric and chromatographic analyses demonstrated greater thermal and solution stability for the hybrids compared to curcumin. Additionally, the hybrid composites effectively developed natural and sebaceous latent fingerprints with good clarity and contrast on glass surfaces. Both composites performed similarly to commercial Gold^® powder. When applied to surfaces representative of forensic scenarios, the composites were versatile, revealing sufficient fingerprint details for human identification on both porous and non-porous surfaces. Scanning electron microscopy images showed greater clarity in sebaceous and natural fingerprints developed with the Fe composite compared to the Cu composite. Full article

Indigo leaves from various plant species are sources of dyes/pigments, not fully exploited for making sustainable textiles. Blue indigo vat dye extracted from indigo leaves yields high wash color fastness but fades slowly with light, and is not easily used for direct printing. Indigo leaves can be used to produce textiles of various color shades, while light-resistant Mayan-inspired hybrid pigments have not yet been used for textile coloring. Using blue indigo dyes from three plant species, with exhaustion dyeing, intense wash-resistant blue-colored textiles are produced, and in the case of Indigofera Persicaria tinctoria, textiles have antibacterial activity against S. epidermis and E. coli. A 100% natural Mayan-inspired blue indigo pigment, made from sepiolite clay and natural indigo dye, was used both in powdered and paste forms to perform pigment textile dyeing by pad cure process, and direct screen printing on textiles. A water-based bio-binder was used efficiently for both padding and printing. Bio-based Na Alginate thickener allowed to produce prints with good color-fastness on both polyester and cotton fabrics, while bio-based glycerin produced excellent print color fastness on polyester only: wash fastness (5/5), dry and wet rub fastness (5/5) and light fastness (7/8). Full article

Aryl polyene (APE) are bacterial pigments which show great biotechnological potential because of their biological activities. In this study, the presence of gene clusters associated with APE synthesis was investigated in the genome of Chryseobacterium sp. kr6 and Lysobacter sp. A03. The pigments extracted from strains kr6 and A03 were further characterized by liquid chromatography coupled to a high-resolution mass spectrometer (LC-DAD-MS). These bacteria harbor the relevant genes for APE biosynthesis; while kr6 may produce flexirubin pigments and have a 75% similarity with the flexirubin cluster from Flavobacterium johnsoniae UW101, Lysobacter sp. A03 showed a 50% similarity with the xanthomonadin I gene cluster from Xanthomonas oryzae pv. oryzae. A comparison with the gene clusters of APE-producing bacteria revealed that kr6 and A03 harbor genes for key proteins that participate in APE biosynthesis, such as acyl carrier proteins, acyl dehydratases and acyl reductases. The LC-DAD-MS analysis revealed that kr6 produces a possible mixture of flexirubins, whereas the yellow pigment from A03 is proposed to be a xanthomonadin-like pigment. Although the fine molecular structure of these pigments are not yet fully elucidated, strains kr6 and A03 present great potential for the production of natural bioactive pigments. Full article

Advancements in cellular imaging have significantly enhanced our understanding of membrane potential and Ca²⁺ dynamics, which are crucial for various cellular processes. Voltage-sensitive dyes (VSDs) are pivotal in this field, enabling non-invasive, high-resolution visualization of electrical activity in cells. This review discusses the various types of VSDs, including electrochromic, Förster Resonance Energy Transfer (FRET)-based, and Photoinduced Electron Transfer (PeT)-based dyes. VSDs are essential tools for studying mitochondrial activity and neuronal function and are frequently used in conjunction with Ca²⁺ indicators to elucidate the complex relationship between membrane potential and Ca²⁺ fluxes. The development of novel dyes with improved photostability and reduced toxicity continues to expand the potential of VSDs in biomedical research. This review underscores the importance of VSDs in advancing our understanding of cellular bioenergetics, signaling, and disease mechanisms. Full article