1-Aminoanthraquinone Diazonium Salt on the Coupling Modification Dyeing of Silk Fibroin with Enhanced Color Fastness

Chromophore incorporated into the protein chains through residue modification on silk fibroin will be an important way to get new dyeing technology with improved color fastness. Herein, 1-aminoanthraquinone diazonium salt was prepared and used for the modified dyeing on tyrosine of silk fibroin. The silk after modified dyeing was measured by UV-Vis, FTIR, MS, ¹H-NMR, Data color, and other testing techniques. Interestingly, the resulting silk showed excellent rub and wash fastness. The enhanced color fastness is contributed by an electrophilic substitution reaction between 1- aminoanthraquinone diazonium salt and the ortho position of phenolic hydroxyl in tyrosine molecular. Moreover, the mechanical property of silk was protected effectively by the mild coupling modified dyeing, better than the traditional acid dyeing under high temperature for a long time. This facile strategy provides an alternative approach to silk dyeing and benefits the silk applications.     

Mechanism and Analysis of Laccase-mediated Coloration of Silk Fabrics

Laccase provides a mild and eco-friendly alternative for the dyeing of fabrics. In this study, laccase-mediated catalytic oxidation was employed in coloration of silk fabrics, and the color was then assessed. The surfaces of silk fabrics were characterized by scanning electron microscope (SEM), atomic force microscopy (AFM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS). Their thermal and crystallization properties were also investigated by differential scanning calorimetry (DSC), thermogravimetry (TG), and Xray diffraction (XRD). The textile softness was evaluated by the bending rigidity (B). In addition, high performance liquid chromatography (HPLC) and ultraviolet-visible (UV-VIS) spectroscopy were employed to analyze hydrolysate of silk fabrics obtained from hydrolysis with hydrochloric acid solution. The results demonstrated that a stable reddish-yellow layer was formed on the surface of silk fabrics by the laccase-mediated coupling of phenol hydroxyl side chains in the silk polypeptide. Moreover, the SEM and AFM observations showed that the surface of colored silk fiber was slick. ATR-FTIR and XPS results demonstrated differences in the C, N, O contents and the functional groups of the uncolored and colored silk fabrics. The DSC, TG, and XRD indicated that the thermal properties of silk fabrics were not affected by laccase and the coupling reaction mainly occurred in the amorphous region. The DMF extraction test further illustrated that covalent bonds were formed between tyrosine residues constituent of silk peptides. Finally, HPLC and UV-VIS results showed that new substances were formed as a result of conjugation between benzene rings.     

Grafting of tyrosine-containing peptide onto silk fibroin membrane for improving enzymatic reactivity

During enzymatic modifications of silk fibroins, the accessibility of tyrosinases to the reactive sites was limited owing to the steric hindrance of tyrosine residues in the fibroin proteins. To improve the reactivity of silk fibroin, a tyrosine-containing peptide (TyrP) was covalently grafted onto the fibroin surfaces using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC). Enzymatic oxidation of the modified fibroins was subsequently carried out with a mushroom tyrosinase, followed by coupling of ε-polylysine (ε-PL) with the generated o-quinone residues of silk fibroins. The efficacy of grafting reaction was examined by means of SDS-PAGE and amine acid analysis. The results indicated EDC treatment might cause the direct self-crosslinks of silk fibroins and TyrP-bridged cross-links of fibroin molecules as well, which led to a noticeable increase in the molecular weight of fibroin proteins. TyrP-grafted fibroins displayed higher reactivity compared to the untreated, and more ε-PL was bonded to the fibroin surfaces when incubating with tyrosinase, resulting in improved wettability and mechanical property. The presented work offers an efficient alternative for the enzymatic modification of the fibroin-based materials with tyrosinase.     

High water content silk protein-based hydrogels with tunable elasticity fabricated via a Ru(II) mediated photochemical cross-linking method

Silk is very promising in the field of biomaterials as a natural biomacromolecule. Silk protein can be made into various forms of materials, including hydrogels. However, silk protein-based hydrogels have not attracted much attention due to its weak mechanical properties. Here, we report high water content silk protein-based hydrogels with tunable elasticity which were fabricated through Ru(II) mediated photochemically cross-linking tyrosine residues in regenerated silk protein. The regenerated silk protein was characterized by Fourier transform infrared spectroscopy (FTIR). The gelation kinetics of the silk protein was studied by rheology measurements. The compressive mechanical properties of the silk protein-based hydrogels was investigated using compressive tests and dynamic mechanical analysis (DMA). Compressive modulus of the hydrogels reached 349±64 MPa at 15 % strain. The fabricated silk protein-based hydrogels were also characterized by Scanning electron microscopy (SEM), revealing an interconnected porous network structure, typical of hydrogels, with an average pore size of approximately 130 μm. Finally, biocompatibility of the silk protein-based hydrogels was demonstrated through cell culture studies using a human fibroblast cell line, HFL1. The reported silk protein-based hydrogels represent a promising candidate for biomaterial applications.     

A study on combining natural dyes and environmentally-friendly mordant to improve color strength and ultraviolet protection of textiles

In this study, natural dyes were extracted from five plants, namely diospyros kaki, dioscorea cirrhosa, millettia (jixueteng), ecliptae, and macrocarpa nucuma, using environmentally-friendly solvents, including ethanol and deionized (DI) water. A plant mordant, tannin extracted from Emblica officinalis G., and a metal mordant, copper sulfate, were used in the pre-dyeing process. Cotton and silk fabric samples were treated using the five natural dyes without and with mordanting for comparison on their color strength and characteristics as well as protection against ultraviolet radiation (UVR). Results revealed that Emblica officinalis G. had the highest total phenol content, followed by dioscorea cirrhosa. The presence of abundant phenolic groups in the natural dyes and mordant makes them effective coloration agents for fabrics. Cotton and silk fabrics dyed using ecliptae without pre-mordanting had the highest K/S values. Silk fabrics had higher K/S values than cotton fabrics, indicating greater color strength in pre-mordanted silk treated with DI water-extracted dyes. Natural mordant used before treatment with natural dyes contribute to significant enhancement in color strength, and Emblica officinalis G. alone could darken the color of cotton and silk fabrics dyed with plant pigment. Moreover, treatment with natural dyes after mordanting can increase ultraviolet protection factor (UPF) and the enhancement in UVR protection is greater and more significant in cotton fabrics than in silk fabrics, and in fabrics treated with DI water-extracted natural dyes than in those treated with ethanol-extracted ones. In conclusion, pre-dyeing with natural mordant followed by treatment with natural dyes extracted using environmentally-friendly solvents can enhance significantly K/S and UPF, offering directions for manufacturing textiles without environmental hazards but with good appearance and health benefits.     

Polyphenol-Assisted Natural Coloration on Various Synthetic Textile Materials

With the increasing awareness of sustainability development and public health in the modern society, environmentally-friendly coloration process draws tremendous attention in the textile industry. Toxic heavy metal mordants are forbidden to be used in the application of natural colorants in the coloration process. In this study, an environmentallyfriendly coloration process with natural colorants on various synthetic textile materials was developed in the presence of dopamine, whose in-situ self-polymerization could produce rich polyphenolic coloration anchors. Using the proposed method, various synthetic textile materials could be easily coloured with natural colorants in a simple process, which is especially suitable to those materials which are difficult to be colored. Compared with the control process, synthetic textile materials were endowed with better exhaustions of natural colorants, as verified by their deeper colour appearance and higher K/S values. The colored materials were also characterized by colorimetric analysis as well as scanning electron microscopy and optical microscopic analysis, which also confirmed the successful application of the proposed coloration process. Moreover, the proposed strategy could also be applied on a wide variety of materials. It is an innovative green coloration process in the textile material fields.     

Study on differences of reaction behavior of phenolic hydroxyl groups with vinyl sulfone reactive dyes and monochlorotriazine reactive dyes

Using p-methylphenol as a model compound for phenolic hydroxyl groups on silk fibroin, the reaction kinetics of two typical of reactive dyes including vinyl sulfone reactive dyes and monochlorotriazine reactive dyes with phenolic hydroxyl groups were studied by reverse phase ion-pair high-performance liquid chromatography. The results showed that, the reaction rates of monochlorotriazine reactive dyes with phenolic hydroxyl groups were by far faster than those of vinyl sulfone reactive dyes, attributed to the stability of resultants from the former. The optimum reaction conditions for phenolic hydroxyl groups with vinyl sulfone reactive dyes and monochlorotriazine reactive dyes were at 50–70 °C and pH=8–9 for the former, and at 85–95 °C and pH=8–9 for the latter. The methods and results in this paper would help to deeply study the reaction mechanisms of reactive dyes with silk fibroin.     

Crosslinking reaction of phenolic side chains in silk fibroin by tyrosinase

Tyrosinase oxidizes the tyrosyl residues in silk fibroin (SF) with oxygen, resulting in the production ofo-quinone residues. Subsequently, the inter- or intramolecular crosslinks are formed by reaction with amino groups in through nonenzymatic process. The measurement of oxygen consumption proved that the tyrosyl residues in SF were mostly oxidized to quinone residues by tyrosinase. The reaction mechanisms were proposed in this study and the crosslinking reaction ofo-quinone residues and the enzymatic oxidation of tyrosyl residues could be confirmed by the measurements of UV,¹H-NMR and GFC.     

Application of <Emphasis Type="Italic">Sterculia Foetida</Emphasis> Fruit Shell Waste Biomolecules on Silk for Aesthetic and Wellness Properties

There has been growing interest in the use of bioresource waste for natural dyeing and finishing. This paper discusses dye extraction from the novel source fruit shell waste of Sterculia foetida and its application on mulberry silk fabric to confer aesthetic coloration and wellness properties such as ultra-violet (UV) protection and antibacterial properties. Treated fabrics showed a substantial increase in color depth and adequate wash, light, and rubbing fastness properties for dyed silk fabrics with and without mordanting. Pre-and post-mordanting of silk fabrics were carried out using mordants such as alum, harda (myrobalan), and copper sulfate. UV-visible spectrophotometric analysis of fruit shell extract (FSE) at different pHs and FSE with three different mordants at neutral pH was used to understand the phenomena of dye-fiber interaction. The treated fabrics characterised by ATR-FTIR, SEM-EDS, and XRD analysis indicate the nature of dye fiber interaction justifying the multifunctional properties. The treated fabric also showed very good ultraviolet protection property and antibacterial properties both against S. aureus and E. coli bacteria even after ten washes. The results indicate that Sterculia foetida fruit shell extract offers an excellent potential as coloration, antibacterial, and ultraviolet protective agent for mulberry silk fabric.     

Copper oxide-carbon nanotube (CuO/CNT) nanocomposite: Synthesis and photocatalytic dye degradation from colored textile wastewater

In this paper, CuO/CNT nanocomposite was synthesized and its photocatalytic dye degradation ability for colored textile wastewater was studied. The characteristics of the nanocomposite were investigated by XRD, SEM and FTIR. The photodegradation of Direct Red 31 (DR31) and Reactive Red 120 (RR120) by CuO/CNT in presence of H₂O₂ was investigated. Photocatalytic dye degradation was determined by UV-vis spectrophotometer. Effects of catalyst dosage, initial dye concentration and salt on photodegradation performance were studied. The photocatalytic dye degradation ability of pure CuO and CuO/CNT nanocomposite is 78 % and 89 % for DR31 and 70 % and 87 % for RR120, respectively. The results showed that CNT increased the photocatalytic activity of CuO. The presence of salt decreases dye degradation efficiency. The dye degradation kinetics by nanocomposite followed first-order kinetic model. The reaction rate at 0.005 g catalyst was 0.0137 and 0.0105 min^-1 for DR31 and RR120, respectively. It was found that the CuO/CNT nanocomposite as a photocatalyst could be used to degrade dyes from colored wastewater.     

Acrylamide assisted photoinitiator-free photografting of acrylamido dyes onto wool

Upon UV irradiation wool fabrics can be photografted with photoactive acrylamido dyes at room temperature without photoinitiaors, which is eco-friendly coloration process compared with conventional adsorption-based dyeing. Acrylamide addition as a comonomer can improve the photografting probably by reducing the steric hindrance between the bulky dyes during the photocopolymerization. Even without photointiators and neutral salts, the optimal K/S values of the photografted wool reached upto 18.7 and 18.5 for Reactive Red 84 and Yellow 39 dyes respectively. The optimal UV-grafting coloration can be achieved when a UV energy of 25 J/cm² was irradiated on the padded fabrics with 6.3 %owf dye containing 0.65 mole ratio of acrylamide to the dyes. Furthermore, the color fastness of the grafted fabrics was as good as those of conventionally dyed fabrics due to the copolymerization of dyes and comonomers.     

Enzymatic grafting of lactoferrin onto silk fibroins for antibacterial functionalization

Enzymatic oxidation of tyrosine side-chains in proteins could produce reactive o-quinones that might subsequently react with the primary amino groups of functional compounds, which provided a worthwhile reference for functionalization of fibrion materials. In the present work the potential for using tyrosinase to graft the bovine lactoferrin onto Bombyx mori silk fibroin was examined. Lactoferrin could adsorb onto silk fibers and covalently bind to the previous enzymatically oxidized fibroin surface. The enzyme-generated quinones in silk fibers also might cause self-crosslinking of fibroin peptides, which led to beneficial changes of silk properties. For the fabric treated with tyrosinase and lactoferrin slight improvements of dyeability and strength were obtained in comparison to the control. The combinedly treated fabric showed encouraging resistance to S. aureus and E. coli, the antibacterial activities reached to 87.0 % and 76.4 %, respectively. The durability of the antibacterial silk was noticeably higher than that of the sample treated with lactoferrin alone.     

Oil Red as a histochemical stain for natural fibers and plant cuticle

Properties of natural fibers are influenced by the nature of their surface. Oil Red was evaluated as a histochemical stain for the waxy components on the surface of cotton and flax fibers and of plant cuticles. A positive reaction for arachidyl stearate and differential staining of fibers after sequential extraction of fatty acids and alcohols indicated that Oil Red stained wax components in plant materials. For cotton (Gossypium hirsutum) fibers, Oil Red stained to a greater extent the regions closest to the seed coat, especially at points where fibers attached to the seed coat. Fiber regions at a distance from the seed coats stained irregularly, suggesting that the wax was unevenly distributed. Flax (Linum usitatissimum) bast fibers, in contrast, did not stain with Oil Red, but the protective stem cuticle was intensely stained. The positive histochemical reaction for cuticle identified non-fiber fragments in processed and cleaned flax fibers, thus providing a quick method to detect visually trash components in fiber and products. Likewise, bast fibers from kenaf (Hibiscus cannabinus) did not stain well with Oil Red, whereas the stem cuticle gave a positive reaction. The general usefulness of Oil Red as a histochemical stain for the plant cuticle was demonstrated in leaves and stems of mature corn (Zea mays) and fresh bermudagrass (Cynodon dactylon) leaves. Oil Red provides a quick, qualitative histochemical method to demonstrate the wax-containing cuticle in plants.     

Thermal Stability of Selected Natural Red Extracts Used as Food Colorants

The color degradation of aqueous solutions of six natural red pigment extracts (elderberry, red cabbage, hibiscus, red beet, Opuntia fruits and red cochineal) used commercially as food colorants was investigated at temperatures between 50 and 90 °C. Color degradation was studied in respect to both spectral properties and visual color. The remaining absorbance at 535 nm as a function of the incubation time and temperature was used to quantify the degradation process. Red cochineal was the most thermoresistant extract with a remaining absorbance of 95 % after 6 h at 90 °C. Anthocyanin extracts (elderberry, red cabbage, hibiscus) showed remaining absorbance percentages of 63.8, 46.1 and 26.7, respectively. Betacyanin extracts (red beet, Opuntia fruits) were the most thermosensitive maintaining only 12.5 and 1.7 %, respectively, of the initial absorbance at 535 nm. Applying a first-order kinetic model to the degradation processes, reaction rate constants (k) and half-life periods (t _1/2 ) were calculated. The temperature dependence of the degradation rate constant obeyed the Arrhenius relationship, with activation energies (E _a ) ranging between 3.02 and 53.37 kJ?mol^?1. The higher activation energy values indicated greater temperature sensitivity. Changes in visual color attributes corroborated the high thermal stability of the red cochineal extract.     

Natural dye extraction from waste barks of Turkish red pine (Pinus brutia Ten.) timber and eco-friendly natural dyeing of various textile fibers

In this study, a natural dye extraction was carried out to isolate dyestuff extract powder from the waste barks of Turkish red pine (Pinus brutia Ten.) timber which is not a common natural dyestuff source. The natural dyestuff powder obtained was applied to cotton, flax, wool, silk, tencel, polyamide and acrylic fibers accompanied by simultaneous application of alum and natural oak ash mordants. Color properties were investigated including rub-, light- and wash-fastness performance. Differently dyed fiber samples exhibited slightly different shades of beige, brown and brownish-yellow depending on the mordant used and fiber type. Alum mordanted samples exhibited better color properties. The highest (63.4) and the second highest (45.3) f(k) color yield values were observed for alum mordanted silk and wool samples, respectively. Dyed fabrics showed excellent wash fastness, very low staining performance, and moderate light- and rub-fastness.     

Novel cationic softener containing MCT reactive dyes for cotton: Synthesis and characterization

Two novel cationic softener containing mono-s-chloro triazinyl reactive dyes together with their analogues were designed. The dyes were synthesized via reacting an N,N-dimethyldodecylamine with p-nitrobenzyl bromide. The resultant was reduced using stannous chloride and hydrochloric acid to produce the primary amine. The quaternary ammonium salt containing primary amine was then diazotized to produce diazonium salt part of azo dye. The diazonium salt was then coupled to H-acid/J-acid reacted with cyanuric chloride and sulfanilic acid. The analogue dyes were prepared via the same route without quaternary ammonium salt making stage. The chemical structures of the novel dyes were characterized by FTIR, ¹H-NMR, and elemental analysis. The spectroscopic properties of the dyes were determined in terms of λ _max and ? _max in aqueous solution.     

Effects of Ethanol Extracts from Grateloupia elliptica,a Red Seaweed,and Its Chlorophyll Derivative on 3T3-L1 Adipocytes: Suppression of Lipid Accumulation through Downregulation of Adipogenic Protein Expression

Grateloupia elliptica (G. elliptica) is a red seaweed with antioxidant, antidiabetic, anticancer, anti-inflammatory, and anticoagulant activities. However, the anti-obesity activity of G. elliptica has not been fully investigated. Therefore, the effect of G. elliptica ethanol extract on the suppression of intracellular lipid accumulation in 3T3-L1 cells by Oil Red O staining (ORO) was evaluated. Among the eight red seaweeds tested, G. elliptica 60% ethanol extract (GEE) exhibited the highest inhibition of lipid accumulation. GEE was the only extract to successfully suppress lipid accumulation among ethanol extracts from eight red seaweeds. In this study, we successfully isolated chlorophyll derivative (CD) from the ethyl acetate fraction (EA) of GEE by high-performance liquid chromatography and evaluated their inhibitory effect on intracellular lipid accumulation in 3T3-L1 adipocytes. CD significantly suppressed intracellular lipid accumulation. In addition, CD suppressed adipogenic protein expression such as sterol regulatory element-binding protein-1 (SREBP-1), peroxisome proliferator-activated receptor-γ (PPAR-γ), CCAAT/enhancer-binding protein-α (C/EBP-α), and fatty acid binding protein 4 (FABP4). Taken together, our results indicate that CD from GEE inhibits lipid accumulation by suppressing adipogenesis via the downregulation of adipogenic protein expressions in the differentiated adipocytes. Therefore, chlorophyll from G. elliptica has a beneficial effect on lipid metabolism and it could be utilized as a potential therapeutic agent for preventing obesity.     

Studying irradiation homogeneity in light aging for historical textile conservation

Instrumental light aging is one of the most important tools for restoration and conservation of historical textiles. It used in testing stability of conservation materials, in addition to its lightening effect during the presentation in the museums. Light fading is an important tool for preparing the aged textile and other polymeric samples especially for archaeological conservation applications. Many fadometers do not give homogeneous exposure for all sample’s areas. This work studies the color changes of silk fabric dyed with turmeric (Curcuma longa L.) mordanted with alum or ferric sulfate. Color change was studied for the exposure periods ranged from five to hundred hours. Three positions of different irradiance levels were measured on the same sample namely (bottom, middle and upper). Individual color change for each position was recorded and studied. The results showed that there is non-homogeneous irradiance distribution due to different positions in fadometer or mordant used.     

The Chemically Synthesized Ageladine A-Derivative LysoGlow84 Stains Lysosomes in Viable Mammalian Brain Cells and Specific Structures in the Marine Flatworm Macrostomum lignano

Based on the chemical structure and the known chemical synthesis of the marine sponge alkaloid ageladine A, we synthesized the ageladine A-derivative 4-(naphthalene-2-yl)-1H-imidazo[4,5-c]pyridine trifluoroacetate (LysoGlow84). The two-step synthesis started with the Pictet-Spengler reaction of histamine and naphthalene-2-carbaldehyde to a tetrahydropyridine intermediate, which was dehydrogenated with activated manganese (IV) oxide to LysoGlow84. Structure and purity of the synthesized LysoGlow84 were confirmed by NMR spectroscopy and mass spectrometry. The fluorescence intensity emitted by LysoGlow84 depended strongly on the pH of the solvent with highest fluorescence intensity recorded at pH 4. The fluorescence maximum (at 315 nm excitation) was observed at 440 nm. Biocompatibility of LysoGlow84 was investigated using cultured rat brain astrocytes and the marine flatworm Macrostomum lignano. Exposure of the astrocytes for up to 6 h to micromolar concentrations of LysoGlow84 did not compromise cell viability, as demonstrated by several viability assays, but revealed a promising property of this compound for staining of cellular vesicles. Conventional fluorescence microscopy as well as confocal scanning microscopy of LysoGlow84-treated astrocytes revealed co-localization of LysoGlow84 fluorescence with that of LysoTracker^® Red DND-99. LysoGlow84 stained unclear structures in Macrostomum lignano, which were identified as lysosomes by co-staining with LysoTracker. Strong fluorescence staining by LysoGlow84 was further observed around the worms’ anterior gut and the female genital pore which were not counterstained by LysoTracker Red. Thus, LysoGlow84 is a new promising dye that stains lysosomes and other acidic compartments in cultured cells and in worms.     

Prediction of mechanical properties of aging B.mori silk fabric based on grey neural network model

This paper presents a grey neural network model for the prediction of mechanical properties of aging B.mori silk fabric. In the experiment, we obtained outdoor natural aging breaking strength of B.mori silk fabric from 8 samples. Then, a grey neural network GNNM (1,1) model is proposed by the means of combining GM (1,1) model with BP artificial neural network to predict mechanical properties of B.mori silk fabric. At the same time, this paper analyzed and compared the GM (1,1) model and GNNM (1,1) model by using prediction error such as the relative percentage error (RPE) and the root mean square error (RMSE). The experimental results show that the RMSE of GNNM (1,1) model is 0.0284 well below 6.1786, which is the RMSE of GM (1,1) model. It indicates the GNNM (1,1) model were better than the normal grey GM (1,1) model, when taken the prediction error as evaluation parameter.