Spectral Characterization of Purpurin Dye and Its Application in pH Sensing, Cell Imaging and Apoptosis Detection.

Purpurin (1,2,4-trihydroxy-9,10-anthraquinone) is a natural red dye obtained from the red madder plant that is widely used in food and dyeing industries. The present study investigated the characteristics of purpurin and its application as a pH-sensitive probe to detect the pH of solutions and intracellular pH of mammalian and bacterial cells. Purpurin exhibited high pH-sensitive behavior, low analytes interference, high stability with pKa of 4.6 and visible colorimetric change. 1H NMR and FTIR studies indicated protonation of phenolic hydroxyl group under acidic condition with hypsochromic shift in the absorption and fluorescence spectra relative to that of basic condition. Cell culture studies using HeLa cells revealed that purpurin is well tolerated by the cells and the fluorescent imaging result indicated excellent cell permeability with possible use of the dye to detect the pH fluctuations in living cells under various physiological conditions such as apoptosis. Microbiological studies indicated that the dye could be used for visualization of bacteria under acidic condition.

Supercritical fluid chromatography for the analysis of natural dyes: From carotenoids to flavonoids.

Plant-derived natural dyes are used in a variety of formulated products, from food to cosmetics and pharmaceutics. In addition to their color, they also provide some bioactivity. While they are mostly analyzed with high-performance liquid chromatography, supercritical fluid chromatography was also employed for several dye families, mostly for carotenoids and chlorophylls, and more recently for anthraquinones and flavonoids. These supercritical fluid chromatography methods are described in this review. Because the dyes have different structures and structural variations (polarity, isomers, etc.), the best chromatographic system to achieve their separation is not always the same. Hydrophobic stationary phases are preferred for the most hydrophobic dyes (chlorophylls and carotenoids) while polar stationary phases are preferred for the polar dyes (anthraquinones and flavonoids). Regarding the mobile phase composition, chlorophylls and carotenoids are best eluted with moderate proportions of co-solvent in CO2 (about 40%), while the most polar glycosylated flavonoids require higher proportions of co-solvent and acidic additives. Because dyes are colorful, ultraviolet-visible detection is often sufficient, while mass spectrometry offers additional structural information. Furthermore, fundamental information can also be gained through chromatographic analysis of dyes: either solubility in supercritical fluids, in view of their extraction, or retention behavior providing an understanding of stationary phase properties.

A Study On the Optoelectronic Parameters of Natural Dyes Extracted from Beetroot, Cabbage, Walnut, and Henna for Potential Applications in Organic Electronics.

In this work, the optoelectronic parameters of natural dyes extracted from beetroot, red cabbage, walnut leaves, and henna were comprehensively investigated, namely the optical energy gap (Eg), extinction coefficient (k), refractive index (n), dielectric constant ([Formula: see text], and optical conductivity ([Formula: see text]. Results showed a high refractive index, dielectric constant and optical conductivity ([Formula: see text] and [Formula: see text]) for the dye extracted from red cabbage, while minimum values of [Formula: see text] and [Formula: see text] were obtained for the henna dye. The transition type of the optical absorption of the dyes was found to be a direct allowed transition, which is taken place between the bonding and antibonding molecular energy levels. The reported results herein are essential in revealing the viability of these natural dyes for potential applications in organic electronics, including organic photovoltaics, photodiodes, and sensors.

Copaifera langsdorffii Desf. bark extract: optimisation of dyeing conditions to wool and colour fastness properties.

The ability to add value to waste materials from industrial operations has come to the attention of the wood processing industry, with reports, for example, of extracts from the bark tree conveying colour and UV protection to textile fibres. The objective of the present work was to expand our developments in this arena by using Copaifera langsdorffii Desf. bark extract as a natural dye for textile dyeing. A complete 2³-statistical experimental design and the central point was elaborated. The results showed that the optimal dyeing conditions were 98 °C, for 60 min, using undiluted bark extract. The dyed fabric was analysed by a spectrophotometer using the CIELAB system for evaluation of the colour strength. The results showed a K/S value of 5.78, and the dyed fabric had good colour fastness to rubbing and washing.

The Removal of Binary Mixture of Dyes by Heterogeneous Fenton Oxidation: Kinetics, Product Identification and Toxicity Assessment.

The removal of mixture of two azo dyes, Acid blue 29 and Ponceau xylidine, was studied by heterogeneous Fenton and Fenton-type processes using hydrogen peroxide and sodium persulphate as oxidants in the presence of and nano and micro- particles as catalysts. The synthesised nano- particles were characterised using analytical techniques viz. FT-IR, TEM, EDX, powder XRD and VSM. We have examined the effects of particle size on the COD removal efficiency and the reusability of the catalyst after optimising pH, and concentrations of catalyst and oxidant. Combination of nano-  and hydrogen peroxide possessed higher COD removal efficiency, which was accelerated in acidic pH and inhibited at pH > 6. Total consumption of hydrogen peroxide confirmed the efficiency of the optimised parameters. The mechanism of the formation of intermediate ions and products are proposed. COD removal and consumption of hydrogen peroxide follow pseudo-first-order kinetics. The toxicity of the solutions was assessed using Aliivibrio fischeri light loss and Escherichia coli growth inhibition assays. Both the assays showed different toxicity levels for the same solution.

Optimization of a Sustainable Protocol for the Extraction of Anthocyanins as Textile Dyes from Plant Materials.

Anthocyanins are the largest group of polyphenolic pigments in the plant kingdom. These non-toxic, water-soluble compounds are responsible for the pink, red, purple, violet, and blue colors of fruits, vegetables, and flowers. Anthocyanins are widely used in the production of food, cosmetic and textile products, in the latter case to replace synthetic dyes with natural and sustainable alternatives. Here, we describe an environmentally benign method for the extraction of anthocyanins from red chicory and their characterization by HPLC-DAD and UPLC-MS. The protocol does not require hazardous solvents or chemicals and relies on a simple and scalable procedure that can be applied to red chicory waste streams for anthocyanin extraction. The extracted anthocyanins were characterized for stability over time and for their textile dyeing properties, achieving good values for washing fastness and, as expected, a pink-to-green color change that is reversible and can therefore be exploited in the fashion industry.

Appraisal of Chitosan-Gum Arabic-Coated Bipolymeric Nanocarriers for Efficient Dye Removal and Eradication of the Plant Pathogen Botrytis cinerea.

The treatment of textile wastewater comprising many dyes as contaminants endures an essential task for environmental remediation. In addition, combating antifungal multidrug resistance (MDR) is an intimidating task, specifically owing to the limited options of alternative drugs with multitarget drug mechanisms. Incorporating natural polymeric biomaterials for drug delivery provides desirable properties for drug molecules, effectively eradicating MDR fungal growth. The current study fabricated the bipolymeric drug delivery system using chitosan-gum arabic-coated liposome 5ID nanoparticles (CS-GA-5ID-LP-NPs). This study focused on improving the solubility and sustained release profile of 5I-1H-indole (5ID). These NPs were characterized and tested mechanically as a dye adsorbent as well as their antifungal potencies against the plant pathogen, Botrytis cinerea. CS-GA-5ID-LP-NPs showed 71.23% congo red dye removal compared to crystal violet and phenol red from water and effectively had an antifungal effect on B. cinerea at 25 µg/mL MIC concentrations. The mechanism of the inhibition of B. cinerea via CS-GA-5ID-LP-NPs was attributed to stabilized microtubule polymerization in silico and in vitro. This study opens a new avenue for designing polymeric NPs as adsorbents and antifungal agents for environmental and agriculture remediation.

First Dye-Decolorizing Peroxidase from an Ascomycetous Fungus Secreted by Xylaria grammica.

BACKGROUND: Fungal DyP-type peroxidases have so far been described exclusively for basidiomycetes. Moreover, peroxidases from ascomycetes that oxidize Mn2+ ions are yet not known. METHODS: We describe here the physicochemical, biocatalytic, and molecular characterization of a DyP-type peroxidase (DyP, EC 1.11.1.19) from an ascomycetous fungus. RESULTS: The enzyme oxidizes classic peroxidase substrates such as 2,6-DMP but also veratryl alcohol and notably Mn2+ to Mn3+ ions, suggesting a physiological function of this DyP in lignin modification. The KM value (49 µM) indicates that Mn2+ ions bind with high affinity to the XgrDyP protein but their subsequent oxidation into reactive Mn3+ proceeds with moderate efficiency compared to MnPs and VPs. Mn2+ oxidation was most effective at an acidic pH (between 4.0 and 5.0) and a hypothetical surface exposed an Mn2+ binding site comprising three acidic amino acids (two aspartates and one glutamate) could be localized within the hypothetical XgrDyP structure. The oxidation of Mn2+ ions is seemingly supported by four aromatic amino acids that mediate an electron transfer from the surface to the heme center. CONCLUSIONS: Our findings shed new light on the possible involvement of DyP-type peroxidases in lignocellulose degradation, especially by fungi that lack prototypical ligninolytic class II peroxidases.

Chitosan-based nanocomposite films incorporated with NiO nanoparticles: Physicochemical, photocatalytic and antimicrobial properties.

The aim of this research was to fabricate active nanocomposite films by incorporation of nickel oxide nanoparticles (NiONPs) (3, 6 and 9% w/w) into the chitosan-based films. The NiONPs were synthesized by solution combustion method and the films were prepared by solvent casting method. The formation of new interactions and increasing of films' crystallinity were confirmed by FT-IR and XRD analyses. Uniform dispersion of NiONPs at lower concentrations and their aggregation at level of 9% was confirmed by FE-SEM observations. Water barrier properties, tensile strength, thermal properties and surface hydrophobicity of films enhanced by addition of 6% NiONPs. Photocatalytic activity of nanocomposites was confirmed by absorption of 72% of methyl orange during 270 min under UV irradiation. The nanocomposite films exhibited good antibacterial activity against gram-positive (S. aureus) and gram-negative (S. typhimurium) bacteria. Therefore, the chitosan-NiONPs nanocomposite films could be used for active food packaging applications and photodecolorization purposes.

Glutaraldehyde-cross-linked chitosan-alginate composite for organic dyes removal from aqueous solutions.

We present an approach for synthesis of a micro-porous composite of two well-known biopolymers, namely chitosan and alginate, using glutaraldehyde as the cross-linking agent. Alginate and chitosan were pre-treated before being mixed, and the two biopolymers' proportions were also monitored. Chitosan was modified using aniline with the help of formaldehyde crosslinker and then the twizer was further crosslinked with alginate using glutaraldehyde. The synthesized composite, glutaraldehyde cross-linked chitosan-alginate composite [(Cs-F-An)-G-Al] was characterized using spectral techniques and employed as a potential adsorbent for three dyes namely Brilliant green, Methyl orange and Patent Blue V. The pHPZC of the material was 7.5 and the maximum monolayer adsorption capacity (Qmax) was found to be 235.82, 198.09 and 117.34 mg g-1 for BG (at pH 8.0), MO (at pH 6.0) and PBV (at pH 3.0) respectively. It was found that the adsorption process follows a Freundlich adsorption isotherm and pseudo second order kinetics. A thermodynamic study revealed that the process of adsorption was enthalpy-driven and spontaneous in nature. Interestingly, the values of the adsorption capacity obtained in column adsorption method are in close agreement with those obtained in batch adsorption experiments, which shows the potential of the synthesized composite for uptake of dyes.

Characterisation and optimisation of a novel laccase from Sulfitobacter indolifex for the decolourisation of organic dyes.

Laccases are multi­copper oxidases that possess the potential for industrial wastewater treatments. In this study, a putative laccase from Sulfitobacter indolifex was recombinantly produced and characterised. The enzyme was found to be stable and active at low to ambient temperature and across a range of pH conditions. The ability of the putative bacterial laccase to catalyse the decolourisation of seven common industrial dyes was also examined. Our results showed that the putative laccase could efficiently decolourise Indigo Carmine, Coomassie Brilliant Blue R-250, Congo Red, Malachite Green and Alizarin in the presence of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) as a redox mediator. Furthermore, the use of enzyme immobilisation technology to improve the operational stability and reusability of the putative laccase was also investigated. We found that immobilising the enzyme through the cross-linked enzyme aggregate method significantly improved its tolerance towards extreme pH as well as the presence of organic solvents. This work expands the arsenal of bacterial laccases available for the bioremediation of dye-containing wastewater.

Facile transformation of carboxymethyl cellulose beads into hollow composites for dye adsorption.

Novel millimeter hollow microspheres were fabricated from carboxymethyl cellulose microspheres and polyethyleneimine using glutaraldehyde as a crosslinking agent. The hollow microspheres prepared with different polyethyleneimine usages and different polyethyleneimine treatment time were investigated deeply and characterized via SEM-EDX, FT-IR, and BET surface area analysis. It was shown that polyethyleneimine could break the coordination bonds between the carboxyl and Al (III) in carboxymethyl cellulose microspheres, leading to the formation of hollow structures. Most importantly, the usage and treatment time of polyethyleneimine can distinctly tailor the structure of the carboxymethyl cellulose microspheres, resulting in the formation of different hollow microspheres with varied shell thickness and size. Most importantly, we found that the prepared hollow microspheres have excellent adsorption performance toward targeted methyl blue under testing conditions. By virtue of the large accessible amount of -NH2 groups and its unique hollow structure, this type of millimeter hollow microspheres have broad application prospects in the treatment of emerging contaminants in wastewater.

Preparation of clinoptilolite/starch/CoFe2O4 magnetic nanocomposite powder and its elimination properties for cationic dyes from water and wastewater.

A new magnetic nanocomposite clinoptilolite (CLT)/Starch/CoFe2O4 was synthesized using co-precipitation method. The prepared magnetic composite powder was utilized for decontamination of methylene blue dye (MBD), methyl violet dye (MVD), and crystal violet dye (CVD) from water media. The BET analysis showed that CLT modification using starch and CoFe2O4 nanoparticles improved its specific surface and the amount of specific surface area for CLT, CoFe2O4, and CLT/Starch/CoFe2O4 powder was reported to be 18.82 m2.g-1, 151.4 m2.g-1, and 104.75 m2.g-1, respectively. Experimental results showed that pH 9 had a vital role in the adsorption process of all three types. Langmuir and Redlich-Petersen isotherm models were well fitted with experimental data. Also, the maximum adsorption capacity of CVD, MBD, and MVD to the desired composite was determined as 32.84 mg.g-1, 31.81 mg.g-1, and 31.15 mg.g-1, respectively. In addition, the kinetic data of the removal process followed a pseudo-first order (PFO) kinetic model. Negative thermodynamic parameters were indicated that the process is spontaneous and exothermic. Finally, ad(de)sorption experiments' results showed that the synthesized nanocomposite adsorbent has an excellent ability to adsorb cationic dyes after several consecutive cycles.

Fly ash modified magnetic chitosan-polyvinyl alcohol blend for reactive orange 16 dye removal: Adsorption parametric optimization.

A magnetic biocomposite blend of chitosan-polyvinyl alcohol/fly ash (m-Cs-PVA/FA) was developed by adding fly ash (FA) microparticles into the polymeric matrix of magnetic chitosan-polyvinyl alcohol (m-Cs-PVA). The effectiveness of m-Cs-PVA/FA as an adsorbent to remove textile dye (reactive orange 16, RO16) from aquatic environment was evaluated. The optimum adsorption key parameters and their significant interactions were determined by Box-Behnken Design (BBD). The analysis of variance (ANOVA) indicates the significant interactions can be observed between m-Cs-PVA/FA dose with solution pH, and m-Cs-PVA/FA dose with working temperature. Considering these significant interactions, the highest removal of RO16 (%) was found 90.3% at m-Cs-PVA/FA dose (0.06 g), solution pH (4), working temperature (30 °C), and contact time (17.5 min). The results of adsorption kinetics revealed that the RO16 adsorption was better described by the pseudo-second-order model. The results of adsorption isotherm indicated a multilayer adsorption process as well described by Freundlich model with maximum adsorption capacity of 123.8 mg/g at 30 °C. An external magnetic field can be easily applied to recover the adsorbent (m-Cs-PVA/FA). The results supported that the synthesized m-Cs-PVA/FA presents itself as an effective and promising adsorbent for textile dye with preferable adsorption capacity and separation ability during and after the adsorption process.

Ionic chitosan/silica nanocomposite as efficient adsorbent for organic dyes.

A new adsorbent from chitosan and anionic silica was prepared by ionic interaction followed by sol-gel process. The obtained nanocomposite was characterized by different techniques: FTIR, XRD, SEM/EDX, TGA, and TEM. The results showed that silica precursor interacts with chitosan and deposits as regular spherical nanoparticles. The methylene blue (MB) adsorption by chitosan/silica nanocomposite achieved the adsorption equilibrium within 60 min. The adsorption method is fitted to the pseudo-second-order kinetic model and the Langmuir adsorption model with a maximum adsorption capacity of 847.5 mg/g at slight alkaline solution. Chitosan/silica composite displayed high regeneration capability and recovery of MB up to five cycles without the loss of the adsorption efficiency. The current study showed that as-prepared chitosan/silica nanocomposite is an appropriate material for the adsorption of organic pollutants from wastewater.

Stable Crystalline Organic-Inorganic Hybrid Indium Phosphate with Dye Removal and Ractopamine Detection Applications.

A highly stable framework of an organic-inorganic hybrid indium phosphate (NTOU-7) was synthesized under hydro(solvo)thermal conditions and structurally characterized by single-crystal X-ray diffraction and solid-state NMR spectroscopy. This is the first example of a post-transition-metal phosphate incorporating tetradentate organic molecules. The In atoms in the inorganic layers are coordinated by imidazole rings of the 1,2,4,5-tetrakis(imidazol-1-ylmethyl)benzene linkers to generate a new solid-state material. NTOU-7 showed high chemical stability and displayed excellent performance for both dye removal and ractopamine (RAC) detection, which are interesting environmental and biosensing applications. The sensitivity and ultralow limit of detection were 607.9 µA·µM·cm-2 and 2.74 × 10-10 mol·L-1 (0.08 ppb), which meet the requirements stated by the Codex Alimentarius Commission (10 ppb RAC residue in beef and pork). The detection performance was confirmed by sensing spiked-in RAC in real pork samples. We also reported the synthesis, characterization, structural stability, dye removal, and sensing properties of NTOU-7.

Anthocyanins from purple passion fruit (Passiflora edulia Sims) rind-An innovative source for nonbleachable pigment production.

Passion fruit rind is a waste product from the beverage industry that is rich in anthocyanins that can be potentially applied as a natural colorant. However, the inherent instability of anthocyanins causes rapid discoloration. In this study, the cyanidin-3-glucoside (C-3-G) in passion fruit rind was extracted using 50% ethanol and converted into nonbleachable pigments by reaction with Oolong tea extracts and acetaldehyde. Reactions over 70 days formed high concentrations of stable nonbleachable pigments (3.07-6.68 absorbance unit [A.U.], in total) such as pyranoanthocyanins, as well as oligomeric and polymeric pigments with ethyl-linked bridges. In C-3-G and acetaldehyde reaction, positive relations were found among acetaldehyde concentration, color density, and nonbleachable pigment concentrations. As for reactions with C-3-G and Oolong tea extract combined with acetaldehyde, greater color density and greater concentrations of nonbleachable pigments (10.80-12.34, 4.25-4.40 A.U., respectively) were formed compared with acetaldehyde alone. In addition, the antioxidant capabilities of the extracts were enhanced after reaction with Oolong tea extracts. The results of this study show a useful method to enhance the stability of anthocyanins from passion fruit rind and also provide greater economic value to this waste product. PRACTICAL APPLICATION: Ripened passion fruits contain a high concentration of anthocyanins in their rind. These anthocyanins can be optimally extracted by ultrasonic assisted solvent extraction to provide stable pigments by inducing acetaldehyde (a volatile compound often found in foods and beverages) into the anthocyanins. These stable pigments have a greater reddish hue in solution than the anthocyanin extracted from the rind and are more stable over a greater pH range. In addition, these stable pigments can be potentially used as colorant throughout the food and cosmetic industry to provide high economical values.

Boosted sono-oxidative catalytic degradation of Brilliant green dye by magnetic MgFe2O4 catalyst: Degradation mechanism, assessment of bio-toxicity and cost analysis.

The magnetic MgFe2O4 nanoparticles (NPs) were fabricated via a facile co-precipitation technique and was comprehensively characterized by XRD, FTIR, SEM, EDX and VSM. The prepared NPs were used as catalyst in presence of ultrasound (US) irradiation to activate persulfate (PS) for generation of sulfate radicals (SO4·-) for boosted degradation of toxic Brilliant Green (BG) dye. Preliminary experiments revealed that highest BG dye degradation efficiency of 91.63% was achieved at MgFe2O4 catalyst dose of 1.0 g/L, PS dose of 300 mg/L, and initial dye concentration of 70 ppm within 15 min of US irradiation. However, only US, US in presence of PS oxidation and US in presence of MgFe2O4 catalyst have shown 20.2%, 83.6% and 45.0% of BG dye removal, respectively. Furthermore, response surface methodology (RSM) based central composite design (CCD) was executed to investigate the effect of interaction between independent variables such as MgFe2O4 catalyst dose (0.5-1.5 g/L), PS dose (150-350 mg/L), initial BG dye concentration (50-150 ppm) and US irradiation time (4-12 min). The RSM based quadratic model was used to predict the experimental data, and the prediction accuracy was confirmed by analysis of variance (R2 = 0.98). The established RSM model has predicted the optimum experimental conditions as MgFe2O4 catalyst dose of 0.75 g/L, PS dose of 300 mg/L, initial dye concentration of 75 ppm and sonication time of 10 min. Subsequently, the treatment cost analysis was performed for all thirty experimental runs of CCD, and the RSM predicted response was found to be evidently optimum as this has delivered best economic condition (140 $/kg of BG removed) with respect to relative dye removal (%). COD removal and residual sulfate analysis have demonstrated satisfactory reduction of COD (90.31%) as well as sulfate ions (42.87 ppm) in the dye solution after treatment. Results of degradation pathway analysis portrayed the transformation of BG molecule (M/Z ratio 385) into simpler fractions with M/Z ratio of 193, 161, 73, and 61. Moreover, the toxicity analysis revealed that sono-catalytically activated PS system has efficiently reduced the toxicity level of BG dye from 93.9% to 5.13%.

Functional chitosan/glycidyl methacrylate-based cryogels for efficient removal of cationic and anionic dyes and antibacterial applications.

In this study, we constructed a novel family of chitosan-based cryogels with antibacterial activity to treat different types of dye wastewater. Glycidyl methacrylate (GMA) cross-linked chitosan (CS) cryogels functionalized with negatively and positively molecules were prepared via thermo-crosslinking and freeze-drying methods. These chitosan-based cryogels present a well-defined three-dimensional microporous network structure with ultra-light and high porosity, and have high water absorption ability. For CS/GMA/SMA cryogels, 71.20% of Cationic Yellow X-8GL (CY) can be removed, and the process kinetics well corresponded to the Pseudo-second order model and Freundlich model. The quantity and percent of Reactive Yellow B-4RFN (RY) removal by CS/GMA/DMC cryogel reached at 224.6 mg/g and 96.11%, which closely fitted the Pseudo-second order model and Dubinin-Radushkevich isotherm. Furthermore, the chitosan-based cryogels showed antibacterial efficacies against E. coli and S. aureus. The prepared chitosan-based cryogels with adsorption and antibacterial properties have great potential for the remediation of dyeing wastewater.

3D porous bioadsorbents based on chitosan/alginate/cellulose nanofibers as efficient and recyclable adsorbents of anionic dye.

Natural polysaccharides are attractive materials for fabrication of eco-friendly biodsorbents for efficient water remediation. However, scarcity of adsorbents that possess features of high stability and adsorption capacity at various pH conditions, low-cost, eco-friendly, and recycleability at the same time still remains a great challenge. Herein, porous ionically crosslinked biofoams were prepared by freeze-drying of chitosan (CS)/sodium alginate (SA) complex (CSA). FTIR and XRD were used to characterize the structure of the bioadsorbents. SEM observations revealed that adsorbents have a 3D interconnected porous structure, which is a favorable morphology for dye adsorption. Accordingly, CSA and its nanocomposite containing 15 wt% cellulose nanofibers (CSAC15) exhibited a fast and efficient adsorption behavior with qm values of 2015 and 2297 mg/g for adsorption of the Eriochrome black-T (EBT) anionic dye, respectively, which are quite outstanding among the developed EBT adsorbents in the literature so far. The CSAC15 preserved its stability and high adsorption capacity at various pH solutions. The adsorption of EBT onto the bioadsorbents was well-described with the pseudo-second order kinetics and Freundlich isotherm. The proposed CSAC15 bioadsorbent featured repeated dye removal capability after five cycles of adsorption.