HBP-NH2 grafted cotton fiber: Preparation and salt-free dyeing properties

In order to achieve salt-free dyeing on cotton fiber with reactive dyes, an amino-terminated hyperbranched polymer (HBP-NH₂) grafted cotton fiber (HGCF) was prepared by the oxidation of cotton fiber with sodium periodate in water and subsequent grafted with an aqueous solution of HBP-NH₂. Fourier transform infrared spectrophotometry (FTIR) of the HGCF indicated that all aldehyde groups of the oxidized cotton fiber have reacted with amino groups of the HBP-NH₂. As a result, the HGCF fabrics prepared under the optimum conditions displayed markedly enhanced colour strength when dyed with reactive dyes using salt-free dyeing. The washing fastness, rubbing fastness and levelling properties of the dyed HGCF fabrics were also good compared with those obtained by conventional dyeing. The zeta-potential of the HGCF in liquid phase was tested and found to be positive at pHs lower than 6.5. The dyeing behaviour of Reactive Brilliant Yellow A-4GLN on the HGCF was found to follow a Langmuir-type adsorption curve.     

Chitosan‐templated bio‐coloration of cotton fabrics via laccase‐catalyzed polymerization of hydroquinone

There is an increasing interest in the development of enzymatic coloration of textile fabrics as an alternative to conventional textile dyeing processes, which is successful for dyeing protein fibers. However, unmodified cotton fabrics are difficult to be dyed through enzyme catalysis due to the lack of affinity of biosynthesized dyes to cotton fibers. In order to improve the enzyme‐catalyzed dyeability of cotton fibers, chitosan was used to coat cotton fabrics as template. A novel and facile bio‐coloration technique using laccase catalysis of hydroquinone was developed to dye chitosan‐templated cotton fabrics. The polymerization of hydroquinone with the template of chitosan under the laccase catalysis was monitored by ultraviolet‐vis spectrophotometer on the absorbance of reaction solution. A significant peak of UV‐vis spectrum at 246 nm corresponding to large conjugated structures appeared and increased with increasing the duration of enzymatic catalysis. The effect of different treatment conditions on the laccase‐catalyzed dyeing of cotton fabric was investigated to determine their optimal parameters of laccase‐catalyzed coloration. Fourier‐transform infrared spectroscopy spectra demonstrated the formation of H‐bond and Schiff base reaction between chitosan and polymerized hydroquinone. Scanning electron microscopy indicated that the surface of dyed cotton fiber was much rougher than that of the control sample. Moreover, X‐ray photoelectron spectroscopy also revealed the existence of the chitosan/polymerized hydroquinone complex and polymerized hydroquinone on the dyed cotton fibers. This chitosan‐templated approach offers possibility for biological dyeing coloration of cotton fabrics and other cellulosic materials.     

Coloured and low conductive fabrics by in situ laccase-catalysed polymerization

Coloured and conductive fabrics were obtained through “in situ” laccase polymerization of catechol and p-phenylenediamine under high-pressure homogenization. Both monomers, catechol and p-phenylenediamine, were polymerized by different laccase forms, namely native, PEGylated and Epoxy-PEGylated. All the catalysts were placed inside a textile fabric bag which served simultaneously as enzyme support and as substrate for coating with the newly produced polymers. The PEGylated laccase forms gave rise to a higher amount of oligomers/polymers and higher colouration level of polyethylene terephthalate (PET), cotton and wool fabrics compared to native laccase. Both functional polymers were able to confer conductivity to the substrates however in a different extent. Fabrics coated with poly(p-phenylenediamine) present higher conductivity, rather due to its polymerized structure than to the amount of polymer produced by enzyme catalysis. Herein a green approach was presented to produce polyphenols with increased fixation onto different textile substrates. These substrates reach high levels of colouration and good fastness behaviour after washing.     

Effect of microbial transglutaminase on dyeing properties of natural dyes on wool fabric

The dyeing properties of three natural dyes – curcumin, gardenia yellow and lac dye – on wool fabric after treatment with microbial transglutaminase (MTGase) have been investigated. After 120 min of MTGase treatment, compared with the fabric only pretreated with chemical and protease, the colour strength of curcumin, gardenia yellow and lac dye increased from 8±0.13, 7.5±0.10 and 22±0.12 to about 12.8±0.20, 11.7±0.20 and 27.0±0.41, respectively. The values of wash fastness for dyed wool fabrics increased from 2 to 4 after MTGase treatment, but the light fastness was not obviously improved. By comparing with mordant dyeing, although the colour strength was poorer, MTGase after-treatment did not cause colour shade changes during dyeing and the wash fastness of dyed wool fabric was similar to that of the pre-mordanted samples.     

中药诃子制备的天然染料对棉织物的染色研究

本文研究由中药诃子制备的天然染料对棉织物染色方法,分别采用非媒、预媒、同媒和后媒四种染色方法,并运用多种媒染剂进行染色试验。研究结果表明:采用优化的铝预媒染色工艺可染得色泽鲜艳,色牢度较好的黄色棉织物。     

Laccase‐catalysed polymeric dye synthesis from plant‐derived phenols for potential application in hair dyeing: Enzymatic colourations driven by homo‐ or hetero‐polymer synthesis

Laccase efficiently catalyses polymerization of phenolic compounds. However, knowledge on applications of polymers synthesized in this manner remains scarce. Here, the potential of laccase-catalysed polymerization of natural phenols to form products useful in hair dyeing was investigated. All 15 tested phenols yielded coloured products after laccase treatment and colour diversity was attained by using mixtures of two phenolic monomers. After exploring colour differentiation pattern of 120 different reactions with statistical regression analysis, three monomer combinations, namely gallic acid and syringic acid, catechin and catechol, and ferulic acid and syringic acid, giving rise to brown, black, and red materials, respectively, were further characterized because such colours are commercially important for grey hair dyeing. Selected polymers could strongly absorb visible light and their hydrodynamic sizes ranged from 100 to 400 nm. Analyses of enzyme kinetic constants, liquid chromatography and electrospray ionization-mass spectrometry (ESI-MS) coupled with collision-induced dissociation MS/MS indicate that both monomers in reactions involving catechin and catechol, and ferulic acid and syringic acid, are coloured by heteropolymer synthesis, but the gallic acid/syringic acid combination is based on homopolymer mixture formation. Comparison of colour parameters from these three reactions with those of corresponding artificial homopolymer mixtures also supported the idea that laccase may catalyse either hetero- or homo-polymer synthesis. We finally used selected materials to dye grey hair. Each material coloured hair appropriately and the dyeing showed excellent resistance to conventional shampooing. Our study indicates that laccase-catalysed polymerization of natural phenols is applicable to the development of new cosmetic pigments.     

Preparation of cationic cotton with two-bath pad-bake process and its application in salt-free dyeing

Cationic cotton was prepared by a designed two-bath pad-bake process with 3-chloro-2-hydroxypropyltrimethylammonium chloride as cationizing reagent to realize recycle utilization of the reagent and continuous processing of cationization. Experiments showed that 8.0% (o.w.bath) of the reagent, 1:1 of molar ratio of sodium hydroxide to the reagent, 60 °C and 6 min of baking temperature and time were selected for cationization and the obtained cationic cotton was suitable for application in salt-free reactive dyeing. The structures of both the untreated and cationic fibers were investigated by X-ray diffraction and scanning electronic microscopy. Higher dye utilization and color yields could be realized on the cationic cotton than that on the untreated one in the conventional dyeing. Levelness dyeing and good fastness properties of the dyes on the cationic fabrics were obtained. Besides, colorimetric properties and mechanical strength of the dyed fabrics were both evaluated to show applicability of this preparation process of cationic cotton.     

Investigation of a green process for the polymerization of catechin

Flavonoids are polyphenolic secondary plant metabolites which possess antioxidant and anti-inflammatory properties. Besides, they have been shown to exhibit increased antioxidant properties in their polymerized form. Catechins are one of the attractive class of flavonoids which belong to the group of flavan-3-ols. Polymerization of catechins have been investigated in numerous studies indicating the requirement of certain amount of organic solvent to provide the solubility of the monomer. However, many research projects have been conducted recently to replace toxic organic contaminants of the processes with environmentally friendly solvents. In this aspect, deep eutectic solvents (DESs) that are regarded as “green solvents” have been studied extensively in various enzyme catalyzed reactions. In the present study, we focused on establishing a green pathway for laccase catalyzed polycatechin synthesis by replacing organic solvent content with DESs as green solvents. For this aim, various parameters were investigated, such as DES types and concentrations laccase amount and reaction time. Consequently, the highest molecular weight polycatechin was obtained using 5% (v/v) B–M, 125?U laccase in 1?hr of reaction time, at 30°C, as 4,354?±?678?g?mol^?1. Corresponding X/XO inhibitory activity and superoxide radical scavenging activities were achieved as, 59 and 50%, respectively.     

The effect of additives and mechanical agitation in surface modification of acrylic fibres by cutinase and esterase

The surface of an acrylic fibre containing about 7% of vinyl acetate was modified using Fusarium solani pisi cutinase and a commercial esterase, Texazym PES. The effect of acrylic solvents and stabilising polyols on cutinase operational stability was studied. The half-life time of cutinase increased by 3.5-fold with the addition of 15% N,N-dimethylacetamide (DMA) and by 3-fold with 1M glycerol. The impact of additives and mechanical agitation in the protein adsorption and in the hydrolysis of vinyl acetate from acrylic fabric was investigated. The hydroxyl groups produced on the surface of the fibre were able to react specifically with Remazol Brilliant Blue R (cotton reactive dye) and to increase the colour of the acrylic-treated fabric. The best staining level was obtained with a high level of mechanical agitation and with the addition of 1% DMA. Under these conditions, the raise in the acrylic fabric colour depth was 30% for cutinase and 25% for Texazym. The crystallinity degree, determined by X-ray diffraction, was not significantly changed between control samples and samples treated with cutinase. The results showed that the outcome of the application of these enzymes depends closely on the reaction media conditions.     

Utilization of acrylates emulsion terpolymer with chitosan as a finishing agent for cotton fabrics

Cotton fabrics were treated with finishing bath formulation containing emulsion lattices based on acrylate monomers, chitosan and polyethylene glycol (PEG) to provide cotton fabrics with antibacterial, UV-protection as well as improvement of dyeing properties with direct, acid and reactive dyes. The terpolymer emulsion, chitosan and PEG concentrations as well as fabric pretreatment with alkali significantly affected the performance properties, antimicrobial activity, UV-protection and dyeing behavior of treated cotton fabric. The finished fabrics were characterized in terms of FTIR, X-ray diffraction, scanning electron microscope (SEM) as well as mechanical properties such as tensile strength, elongation at break (%), abrasion resistance and air permeability. The obtained data showed that the tested fabrics have appropriate antibacterial activity with highly UV-protection properties with increasing chitosan concentration up to 3%. The mechanical properties expressed as tensile strength and abrasion resistance increased after finishing treatment. Moreover, the performance of the finished fabrics and dyeing properties with different dyes classes were greatly influenced by the action of alkali pretreatment of cotton fabrics, adding the polyethylene glycol to the finishing bath formulation as well as emulsion and chitosan concentrations.     

Peculiarities of direct bioelectrocatalysis by laccase in aqueous-nonaqueous mixtures

The effect of concentration of ethanol and dimethyl sulfoxide on the catalytic activity of laccase is studied for the enzymatic reaction of catechol oxidation and bioelectrocatalytic reaction of oxygen reduction under the conditions of direct electron transfer. Laccase-Nafion composite is elaborated ensuring the enzyme stability in a wide potential range and a content of organic solvents. Based on the STM measurements, the structure of composite layer is proposed. It is shown that the mechanism of oxygen reduction reaction by laccase in organo-aqueous mixtures is similar to that earlier proposed for aqueous solutions. A decrease in the electrocatalytic activity of laccase in the oxygen reduction correlates with a decrease in the laccase enzymatic activity in the substrate oxidation. However, a decrease in the laccase activity in the composite is observed at a higher content of organic solvent in the mixture. The mechanism of laccase inactivation by organic solvents is proposed.     

Immobilized laccase for decolourization of Reactive Black 5 dyeing effluent

Reactive Black 5 industrial dyeing effluent was decolourized by free and immobilized laccase. The stability of the enzyme (194 h free and 79 h immobilized) depended on the dyeing liquor composition and the chemical structure of the dye. In the decolourization experiments with immobilized laccase, two phenomenons were observed – decolourization due to adsorption on the support (79%) and dye degradation due to the enzyme action (4%). Dyeing in the enzymatically recycled effluent provided consistency of the colour with both bright and dark dyes.     

汽爆秸秆漆酶协同作用提取木质素

组分分离是秸秆炼制的关键技术。本文建立了汽爆耦合漆酶协同作用工艺,研究其对秸秆物理形态、化学组成以及木质素碱提取过程的影响。研究结果表明汽爆破坏秸秆表面致密结构,提高比表面积,促进漆酶对秸秆木质素的氧化作用;红外分析表明,漆酶破坏了汽爆秸秆中半纤维素酯键,且愈创木基吸收峰减弱,漆酶削弱了木质素与纤维素间相互作用;汽爆漆酶协同作用后的秸秆木质素提取率提高约20%(70℃,120 min)。Nuclei Growth模型分析温和条件下秸秆木质素提取过程,动力学结果表明,汽爆漆酶协同预处理增加了汽爆秸秆木质素碱提过程中反应起始作用位点,并提高了该过程对温度的敏感性。汽爆-漆酶协同预处理是一种有效的分离木质素的方法,将在木质纤维素原料的生物炼制中发挥重要作用。     

Functionalization of cotton fabric with PVP/ZnO nanoparticles for improved reactive dyeability and antibacterial activity

Poly-N-vinyl-2-pyrrolidone functionalization was done for improved the dyeability of dichlorotriazine dyes on cotton fabric. The synthesized ZnO nanoparticles were padded on functionalized cotton fabrics to improve antibacterial activity. The modification effects were characterized by FTIR, XRD, SEM and EDX studies. The antibacterial activity was done against Staphylococcus aureus and Escherichia coli bacterium. The dye exhaustion and fastness properties were analyzed for dyeing with sodium chloride, sodium sulfate and trisodium citrate bio-salt as exhausting agents. The functionalized cotton fabric showed improved dye uptake and good fastness properties. Poly-N-vinyl-2-pyrrolidone with ZnO nanoparticles padded fabrics showed very good antibacterial activity.     

Dyeing properties, synthesis, isolation and characterization of an in situ generated phenolic pigment, covalently bound to cotton

Oxidation of colourless dye precursors with laccase enzyme provided simultaneous “in situ” generation and fixation of a pigment on amino groups pre-functionalized cotton fabric. Aromatic amine moieties of 2,5-diaminobenzenesulfonic acid introduced onto tosylated cotton were coupled and copolymerised with a phenolic compound catechol into coloured product covalently fixed on the fabric upon oxidation with laccase. The controlled amination of cellulose in a first step and subsequent colouration allowed for up to 95% pigment fixation on the fabric. Electrochemical studies were performed to elucidate the mechanism of the pigment formation. The pigment was further isolated from the acid hydrolysate of the dyed cellulose fabric to confirm the covalent fixation and to further elucidate the pigment structure by means of FTIR, MS, ¹H and ¹³C NMR analysis. An oligomeric pigment has been identified composed by up to six phenolic units.     

Comparing the efficiency of the laccase–NHA and laccase–HBT systems in eucalyptus pulp bleaching

Laccase–mediator systems have the disadvantage that the mediator is expensive and potentially toxic. In this work, we used N-hydroxyacetanilide (NHA) in combination with laccase for the first time to bleach eucalypt pulp and found it to be a very promising, advantageous alternative to 1-hydroxybenzotriazole (HBT) as mediator. Thus, NHA is efficiently oxidized by laccase to a radical that absorbs light at 350 nm. Also, NHA is a better substrate for laccase than is HBT. An innovative result is that the enzyme is inactivated to a similar extent by both mediators under the typical treatment conditions of the bleaching step (L). This adverse effect, however, is strongly reduced in the presence of pulp. Moreover, the laccase–NHA system is as efficient as the laccase–HBT system in reducing the kappa number of eucalyptus pulp. Using a xylanase pretreatment or unbleached pulp boosts kappa number reduction and bleaching with the laccase–mediator system. Based on the results of cyclic voltammetry tests, NHA has a slightly lower redox potential than HBT, which further supports use of the former; also, unlike HBT, NHA is oxidized in a reversible, pH-dependent manner. Interestingly, the laccase–NHA system provides more efficient bleaching of eucalyptus pulp at pH 5 than it does at pH 4.     

Enzymatic colouration with laccase and peroxidases: Recent progress

Enzymes have received significant attention as alternative catalysts to chemical auxiliaries in textile processing. For example, laccases and peroxidises are promising alternatives for bleaching and denim stone washing processes. Similarly, the ability to oxidise different phenolic substrates and dye precusors resulting in the formation of different coloured polymeric molecules is being exploited for developing green chemistry dyeing processes. The enzymatic process is simpler than conventional coloration processes, giving economic and environmental benefits. In this review, the applications of laccase and peroxidise enzymes in dyeing processes of various textile meterials is discussed.     

The environmental control of colouration in a bushcricket, Mygalopsis marki Bailey (Orthoptera: Tettigoniidae)

The environmental factors proximately influencing variable colouration in the bushcricket, Mygalopsis marki , were studied in natural populations and under controlled laboratory conditions. Two major components of variable colouration were identified; a green/brown dimorphism in ground colour hue (dominant wave length) and continuous variation in the darkness of brown insects, representing a contrast between ground colour value (brightness) and the intensity of overlying black pattern. Ground colour hue differed between natural populations in different seasons and at different localities. The proportion of brown individuals was greater in populations developing over late summer than over spring at the same locality, and in populations from drier localities, as indicated by vegetation type, in the same season. Experimental studies showed that colour change occurred at moults, with green colouration promoted by increased water intake in developing nymphs. Ground colour value and pattern differed between natural populations at different localities, but not in different seasons. Ground colour value was less, and pattern was greater, in populations from localities with a dense cover of forbs and grasses. Experimental studies showed that ground colour value and pattern were influenced by the intensity of incident radiation received by developing nymphs, with decreased intensity promoting lower value and greater pattern.     

Laccase-mediated system pretreatment to enhance the effect of hydrogen peroxide bleaching of cotton fabric

This study evaluates the bleaching efficiency of the hydrogen peroxide bleaching process combined with laccase-mediated system pretreatment (LMS-HPBP) in the treatment of scoured cotton fabric. By changing the factors of laccase-mediated system pretreatment and the hydrogen peroxide bleaching process and examining the subsequent whiteness value and retained tensile strength of the samples, we find three LMS-HPBP processes that are more environment friendly than the conventional hydrogen peroxide bleaching process (CHPBP): (i) bleaching with lower dosage of hydrogen peroxide; (ii) bleaching at reduced temperature; (iii) bleaching for shortened duration. Whiteness, retained tensile strength and K/S values of cotton fabric samples treated by i-iii processes were similar to or higher than those by CHPBP. X-ray diffraction (XRD) analysis also demonstrated that the three processes rendered fabric of both lower crystallinity and bigger crystallite size than those by CHPBP. In addition, the "green" short-flow process was developed to treat cotton fabric and the results obtained shows this method is feasible as a new energy-saving process.     

Genipa americana L.: A New Phytochemical for White Hair Coloring

This work describes a new hair dyeing methodology using a chemical reaction between geniposide, an iridoid glycoside extracted from the fruit of Genipa americana (geniposide extract, GE) and the amine group of hair keratin. The influence of reaction conditions (pH, temperature, and extract concentration) on the staining of hair fibers, color development, fiber morphology, and mechanical hair properties of black and white human hair samples, was evaluated before and after GE dyeing treatment. Eye contact safety of GE was also studied using HET-CAM. The treatment of white hair fibers using GE at 20 mg mL⁻¹, temperature of 80 °C and pH 5.5 presented the greatest color change (ΔE=54.0). The higher pH influence was observed at pH 10.0 on white hair tresses (ΔE=6.8), using an GE concentration of 20 mg mL⁻¹ and room temperature (25 °C). Treated samples showed marked changes on mechanical and morphological properties. The HET-CAM did not show any change, thus demonstrating that using GE is safe. In conclusion, the temperature and concentration of the extract were the variables that mostly influenced the color and hair damage. A new approach for hair dyeing was established where iridoids may potentially be useful as a natural hair dyeing.