Enzymatic treatment of wool pre-treated with cetyltrimethylammonium bromide to achieve machine washability

Knitted wool fabric was pre-treated with cetyltrimethylammonium bromide in alkaline conditions in order to remove surface lipid to make the fibre more hydrophilic to enable more efficient subsequent treatment with the enzyme protease. As residual cetyltrimethylammonium bromide on the fibre surface causes an inhibitory effect towards protease, cetyltrimethylammonium bromide has to be removed from the wool. The efficacy of three different anionic surfactants in acid conditions was examined for removing residual cetyltrimethylammonium bromide from the treated wool. If the cetyltrimethylammonium bromide-treated knitted wool was washed with the anionic surfactant, Libraphos HC2A, in acidic conditions, followed by treatment with a chemically modified protease, machine-washable standards could be achieved. The possibility of whether native protease could be used instead of chemically modified protease in achieving shrink-resistance without excessive fibre damage was also studied, exploiting the tendency of residual cetyltrimethylammonium bromide to decrease the activity of the enzyme. It was found that if native protease or native protease in the presence of an enteric polymer was used to treat cetyltrimethylammonium bromide pre-treated wool, an improvement in shrink-resistance without excessive fibre degradation was observed. Machine washability could be achieved by optimizing the proportion of enteric polymer to native protease used to treat cetyltrimethylammonium bromide pre-treated wool. Up-scaling this process showed similar results. The dyeability of the wool with reactive dyes was unaffected by the treatment.     

Bio‐antifelting of wool based on mild methanolic potassium hydroxide pretreatment

Covalently bound lipids cover the wool surface and make enzymatic degradation of wool scales very difficult. In this paper, methanolic potassium hydroxide (MPH) pretreatment was used prior to enzymatic treatment of wool with protease, aiming at hydrolyzing the outmost lipids on the wool surface and promoting the subsequent proteolytic reaction. The efficacy of lipid removal from the fiber surface and the properties of the protease‐treated wool were evaluated. The results indicated that mild MPH pretreatment with 0.10 mol/L MPH for 10 min improved the wettability of the wool without adverse impacts on its mechanical properties. The wetting time and area shrinkage of the wool fabric reached 0.5 s and 5.6%, respectively, and the strength loss was within the acceptable range. Pretreatment with high concentrations of MPH for longer times led to significant damage to the wool fibers and caused heavy strength loss, without improving the antifelting properties after protease treatment. Thus, the combination of mild MPH and protease treatments endowed the wool with desirable properties in contrast to the treatment with protease alone.     

Extremozymes for improving wool properties

The project ‘EXTRETEX’ funded by the German Federal Foundation Environment (DBU, Osnabrück, Germany) aims at the improvement of wool properties dyeability, handle, felting behaviour and degree of whiteness by means of enzymes derived from extremophilic micro-organisms. In this paper the effects of a commercial thermo- and alkalistable protease on wool with regard to the degree of whiteness, the dyeability and the felting behaviour are presented. A method to treat wool top and wool fabric was developed on a laboratory scale in which the protease was integrated into the pre-washing step of a dyeing process. This treatment method was than scaled up and tested on an industrial winch beck for fabric. With this method—the addition of enzyme in the pre-washing step—the degree of whiteness is generally enhanced. Dyeing untreated and the enzyme-treated wool with Lanasol Blue 8G leads to an improved dyestuff uptake and a distinctive difference in the colour shade for the latter. Microscopy pictures of fibre cross-sections of these samples display a more even distribution of the dyestuff and a better penetration in the enzyme-treated wool fibres but the colour fastness of the enzyme-treated wool is decreased. Though the felting behaviour of the protease treated wool is significantly improved the felting tendency is still too high for an antifelting finish. An increased damage of the enzyme-treated wool in comparison with the untreated one was not observed.     

Promotional effect of 1‐butyl‐3‐methylimidazolium chloride ionic liquid on the enzymatic finishing of wool

To improve the effects of protease finishing on wool, 1‐butyl‐3‐methylimidazolium chloride ionic liquid was employed as a pretreatment reagent. It was found that ionic liquid pretreatment significantly changed the wool surface characteristics. The Allwördern reaction showed that the epicuticle layer was damaged by the ionic liquid, and X‐ray photoelectron spectroscopy analysis further demonstrated that the surface elemental composition was significantly changed. Ionic liquid pretreatment remarkably improved the accessibility of protease to the wool and thus accelerated the hydrolysis rate of keratin. The properties of wool fabric after combined processing were also changed. Dyeability results showed that the color depth was increased but the wet rubbing and washing fastness of wool fabrics showed a decreased half grade. The wettability results demonstrate that the contact angle was further reduced after the comprehensive treatment because of the exposure of more proteins under the fatty‐acid layer. In addition, the shrink proofing of wool fabric was also enhanced after combined processing. In summary, ionic liquid modification presents a promising pretreatment method for protease processing of wool.     

Preparation and application of nanochitosan to finishing treatment with anti-microbial and anti-shrinking properties

In this study, we used low-molecular-weight chitosan (LWCS) to prepare nanochitosan (NCH) and applied this material to wool fabric finishing treatment. The diameters and zeta potential of the nanochitosan decreased as the value of the molecular weight of chitosan decreased. Additionally, the wool fabric was treated with various types of chitosan. The anti-bacterial and shrink-proofing properties of the treated fabric are ranked as following: NCH > LWCS > chitosan. The former two properties also increased as the concentration of nanochitosan increased. In addition, the nanochitosan-treated wool fabric possesses better anti-bacterial and shrink-proofing properties after washing for 20 times.     

The removal of lipid from the surface of wool to promote the subsequent enzymatic process with modified protease for wool shrink resistance

Abstract

When treated with modified protease, wool shows shrink resistance without significant damage to the fiber. It was considered that if wool fiber was pre-treated to make it more hydrophilic, the subsequent treatment with modified protease would be more efficient. After wool was pre-treated with cetyltrimethylammonium bromide (CTAB) under alkaline conditions, the fiber became very hydrophilic due to the removal of surface lipid. After CTAB treatment, it was found that residual CTAB on the fiber significantly decreased enzyme activity. Therefore prior to enzyme treatment, CTAB was washed off the fiber with anionic surfactant under acidic conditions. It was found that the activity of modified protease towards wool improved if wool had been pre-treated with CTAB then washed with anionic surfactant. It was concluded that pre-treatment of wool with CTAB under alkaline conditions followed by washing with anionic surfactant improves the wettability of wool and therefore promotes more efficient treatment with modified protease, achieving improved levels of shrink resistance with no effect on strength of the fiber or coloration properties.     

Effect of proteolytic enzyme on dyeing of wool with madder

In recent years, the use of low-environmental impact biotechnology giving rises to new types of treatment in the textile industry. The use of protease enzymes to improve some physical and mechanical properties such as smoothness, drapeability, dyeing affinity and water absorbency is particularly interesting. In this research, wool yarns were first treated with different concentrations of protease enzymes in water solution including 1, 2, 4 and 6% o.w.f. for 60 min. The dyeing process was then carried out on the treated yarns with madder (50% o.w.f.). Tensile strength of treated yarns was decreased due to enzyme treatment and it continued to decrease with an increase in enzyme concentration in solution. The L^* values decreased for the samples treated with enzyme. The wash and light fastness properties of samples were measured according to ISO 105-CO5 and Daylight ISO 105-BO1. The washing fastness properties of treated samples were not changed. In the case of light fastness properties, it was increased a little for 4% and 6% enzyme treated samples.     

Combined use of mild oxidation and cutinase/lipase pretreatments for enzymatic processing of wool fabrics

A cutinase from Thermobifida fusca WSH04 and two lipases, L3126 and Lipex 100L, were applied to the enzymatic pretreatment of wool fabrics followed by protease treatment, aiming at hydrolyzing the outmost bound lipids on the wool surface. A mild oxidation with 2 g/L hydrogen peroxide (30%) was selectively carried out before the enzymatic treatments. The cooperative actions of mild oxidation, cutinase and lipase pretreatments during wool processing were investigated. The results showed that lipase pretreatment alone had less impact on the wettability and anti‐felting ability of wool fabrics than cutinase treatment. Combined use of cutinase and lipase pretreatments did not evidently improve the properties of the wool fabric compared with the individual cutinase pretreatment. By contrast, mild oxidation slightly enhanced the activity of cutinase toward the wool surface and promoted the subsequent proteolytic reactions. The wetting time and contact angle of the protease‐treated fabric deceased to 1.2 min and 55°, respectively; the area shrinkage decreased to 3.1%, with an acceptable strength loss from 489 to 418 N. The changes in the cuticle scales of the wool fibers, confirmed by scanning electron microscopy, further proved the cooperative actions of mild oxidation and cutinase pretreatment during enzymatic wool processing.     

Restricting detergent protease action to surface of protein fibres by chemical modification

Due to their excellent properties, such as thermostability, activity over a broad range of pH and efficient stain removal, proteases from Bacillus sp. are commonly used in the textile industry including industrial processes and laundry and represent one of the most important groups of enzymes. However, due to the action of proteases, severe damage on natural protein fibres such as silk and wool result after washing with detergents containing proteases. To include the benefits of proteases in a wool fibre friendly detergent formulation, the soluble polymer polyethylene glycol (PEG) was covalently attached to a protease from Bacillus licheniformis. In contrast to activation of PEG with cyanuric chloride (50%) activation with 1,1′-carbonyldiimidazole (CDI) lead to activity recovery above 90%. With these modified enzymes, hydrolytic attack on wool fibres could be successfully prevented up to 95% compared to the native enzymes. Colour difference (ΔE) measured in the three dimensional colour space showed good stain removal properties for the modified enzymes. Furthermore, half-life of the modified enzymes in buffers and commercial detergents solutions was nearly twice as high as those of the non-modified enzymes with values of up to 63 min. Out of the different modified proteases especially the B. licheniformis protease with the 2.0-kDa polymer attached both retained stain removal properties and did not hydrolyse/damage wool fibres.     

Detergent Formulations for Wool Domestic Washings Containing Immobilized Enzymes

The stability of immobilized and native Esperase, a commercial serine protease, was studied by incubating the enzymes in four formulations containing the same amount of anionic and non-ionic surfactants. The results show that the activity of the immobilized enzyme is not affected by the presence of detergents while the native enzyme lost 50% of activity after 20 min of incubation in these four formulations. The washing performance of the detergents prepared with the immobilized Esperase was studied on cotton and wool fabric samples stained with human blood and egg yolk, using as control the detergent containing native Esperase. The best stain removal for cotton samples stained with human blood was achieved using the detergent with immobilized Esperase. Several physical tests confirmed that wool keratin was not degraded by the immobilized Esperase, validating the ability to use formulated detergents containing this immobilized enzyme for safe wool domestic washing.     

An evaluation of the action of thioesterases on the surface of wool

The thioesterase activity of palmitoyl protein thioesterase (PPT1) and six commercial lipases was measured against the synthetic substrates, S-palmitoyl-N-acetylcysteamine (Ac-Cym-Pal) and S-(18-methyleicosanoyl)-N-acetylcysteamine (Ac-Cym-18-MEA). PPT1 showed good activity against Ac-Cym-Pal but relatively low activity against the longer chain substrate, Ac-Cym-18-MEA. The highest activity was given by Lipolase 100L type EX (Novozyme) and Lipoprotein Lipase (Sigma) with greater than 90% hydrolysis of Ac-Cym-18-MEA within 10 min at pH 7.4. Other lipases to show high levels of thioesterase activity include Lipex 100L (Novozyme), Lipomod 34P (Biocatalysts) and Lipozyme CALB L (Novozyme). Chemical analysis of wool fibre and fabric treated with the above enzymes under optimal conditions showed that there was no hydrolysis of 18-MEA or other covalently bound fatty acids from the fibre surface. No change in the wettability of the fabric surface was observed following enzyme treatments. Scanning electron micrographs of the fabric treated with the most active enzyme, Lipolase 100L type EX, revealed that the surface of the fibres appeared to have a coating that was not removed by extensive extraction. Reasons for the inability of PPT1 and the other esterases to hydrolyse 18-MEA from the wool fibre surface are discussed.     

Antibacterial functionalization of wool fabric via immobilizing lysozymes

Greater attention has been given to enzymatic processes of textiles as effective alternatives to conventional chemical treatments because of the non-toxic and eco-friendly characteristics of enzymes as well as the increasingly important requirement for reducing pollution in textile production. A new functionalization method for wool fabrics based on immobilization of lysozymes was investigated in this paper. Wool fabric was first activated with glutaraldehyde, and then employed to covalently immobilize lysozymes. Main immobilization parameters were optimized in terms of the activity of immobilized enzyme. A high activity of the immobilized enzyme was obtained when the fabric was activated at 25 °C for 6 h in a bath containing with 0.2% of glutaraldehyde followed by the immobilization at 4 °C and pH 7.0 for 6 h with 5 g l⁻¹ lysozyme. The scanning electron microscopy and staining tests based on modified Coomassie protein assay (Bradford method) revealed that the lysozyme was fixed covalently on the wool fabric. Wool fabrics immobilizing lysozymes presented a higher ratio of bacteriostasis to Staphylococcus aureus. The durability of antibacterial wool was assessed and the lysozyme immobilized on wool fabric retained ca. 43% of its activity after five cycles of use when taking the activity of the immobilized lysozyme before using as reference.     

Wool-associated proteolytic bacteria,isolated from Portuguese Merino breed

The main purpose of this study was to isolate and briefly characterize proteolytic bacteria from a poorly known habitat – raw wool. Fleece samples were accordingly collected from Merino raw wool – a Portuguese ewe breed, at three distinct areas of their body, from animals exhibiting no symptoms or signs of abnormalities; they were then subjected to enumeration and isolation of a total of 158 bacterial strains. Said isolates were screened for protease activity, using the spot technique, on Calcium Caseinate Agar containing 1% (w/v) skim milk. The 36 isolates displaying the highest protease activity underwent a more refined assessment of enzymatic performance – by examining their cell-free supernatant extracts, using casein as substrate. Two Bacillus isolates were eventually chosen owing to their highest proteolytic activities (24.6 and 15.9 U/mL), and identified using molecular biology tools.     

麻栎壳斗染料在羊毛染色中的应用

本文研究了提取自麻栎壳斗的植物染料(麻栎染料)的耐酸、碱稳定性,染浴pH值及铝、铁离子等环保型媒染剂对其染毛织物效果的影响,并且探究了其染色动力学.研究表明,麻栎染料在强酸性染浴(pH=3)中对羊毛织物直接性好,染色后毛织物得棕色,也可采用铝离子、铁离子对直接染色后的毛织物进行后媒染,以得到不同色相的毛织物,尤其是铁后...     

Treatment of wool fibres with subtilisin and subtilisin-PEG

In this work the diffusion of serine proteases into wool fabrics and yarns was studied. The proteases used were free subtilisin and subtilisin-PEG (the same enzyme that was covalently cross linked to polyethylene glycol). It is shown that the adsorption and diffusion is facilitated by the pre-treatment performed, being the alkaline surfactant washing and bleaching the most effective in what concerns enzyme adsorption. Furthermore, this study suggests that the diffusion of proteases into wool is dependent on the size of the protease. The free enzyme penetrates into wool fibre cortex while the modified bigger enzyme is retained only at the surface, in the cuticle layer. Also, proteins without proteolytic activity do not adsorb considerably on wool due to its hydrophobic nature, therefore the diffusion is facilitated by hydrolytic action.

These results have important practical implications for the establishment of enzymatic wool finishing processes, since they allow for control of the enzyme hydrolysis, which was the major drawback of this environmental friendly option to the conventional chlorine treatments.     

Evaluation of bluetongue virus (BTV) decontamination techniques for caprine embryos produced in vivo

The objective of this study was to investigate methods of decontaminating early goat embryos that had been infected in vitro with bluetongue virus (BTV). Embryos were isolated from in vivo-fertilized BTV-free goats. Zona pellucida (ZP)-intact 8 to 16 cell embryos were cocultured for 36 h in an insert over a Vero cell monolayer infected with BTV serotype 8. The embryos were then treated with one of five different washing procedures. The treatment standard (TS) comprised phosphate-buffered saline (PBS) + 0.4% BSA (five times over for 10 s), Hank's +0.25% trypsin (twice for 45 s), and then PBS + 0.4% BSA again (five times for 10 s). The four other washing procedures all included the same first and last washing steps with PBS but without BSA (five times for 10 s) and with PBS + 0.4% BSA (five times for 10 s), respectively. The intermediate step varied for each washing procedure. Treatment 1 (T1): 0.25% trypsin (twice for 45 s). Treatment 2 (T2): 0.25% trypsin (twice for 60 s). Treatment 3 (T3): 0.5% trypsin (twice for 45 s). Treatment 4 (T4): 1% hyaluronidase (once for 5 min). After washing, the embryos were transferred and cocultured with BTV indicator Vero cell monolayers for 6 h, to detect any cytopathic effects (CPE). The effectiveness of the different washing techniques in removing the virus was evaluated by RT-qPCR analysis. The TS, T1, T3, and T4 trypsin or hyaluronidase treatments did not eliminate BTV; Treatment 2 eliminated the virus from in vitro infected goat embryos.     

Effects of cutinase on the enzymatic shrink-resist finishing of wool fabrics

A novel microbial cutinase from Thermobifida fusca WSH04 was applied in the pretreatment of wool fabrics followed by protease treatment, aiming at improving the wettability of the samples by hydrolyzing the outmost bound lipids in the wool surface. Cutinase pretreatment could increase the efficacy of the subsequent protease treatment by improving the wettability, dyeability, and shrink-resistance of the wool fabrics. The data obtained by the XPS method showed the changes of elemental concentration in the wool surface after cutinase pretreatment. Compared with the fabrics treated with hydrogen peroxide and protease, the combination of cutinase and protease treatments produced better results in terms of wettability and shrink-resistance with less strength loss. The anti-felting property of the fabrics treated with the enzymatic resist-shrink technique is very promising to meet the commercial standard.     

Modification of wool surface by liposomes for dyeing with weld

In this research work, wool surface has been modified by liposome to investigate its effects on dyeing with weld, a yellow natural dye. To do this, samples were first treated with aluminium sulphate and afterward with different concentrations of liposomes at various temperatures for 30?minutes and, finally, dyed with weld at 75, 85, and 95°C for 30, 45, and 60?minutes. K/S values of fabric samples were calculated and washing, light and rub fastness properties of the samples were indicated. The results proposed that the sample treated with 1% liposomes and dyed at 75°C for 60?min has the highest K/S value. The central composite design (CCD) used for the experimental plan with three variables on the results of color strength and statistical analysis confirms the optimum conditions obtained by the experimental results. It was also found that washing, light, wet, and dry rub fastness properties of samples dyed with weld, including liposomes, have not significantly changed. The results of water drop absorption indicated that the hydrophobicity is higher for the samples pretreated with liposomes. The SEM picture of wool sample treated with mordant and liposomes and finally dyed with weld shows a coated layer on the fiber surface.     

Wool Fibres: Sectioning and Staining, Differentiation of Ortho and Paracortex

A double embedding technique for tangential sectioning of hair and wool fibres is as follows: The cleaned fibre bundle is attached to a U-shaped, 16 gauge, tinned-copper wire frame with collodion adhesive, soaked in 6% nitrocellulose for 1 hr, and treated with chloroform for 2 hr. The hardened bundle is then cut fom the wire support and embedded in paraffin-beeswax, 95:5. Sectioning is at 6-8 μ. The use of 2% orange G or saturated aqueous picric acid for quantitative study of the fibres, and the demonstration of wool fibre cortical fractions by staining with polychrome methylene blue after oxidation of the sectioned fibres in a solution of formic acid (98/100 w/v) 25 ml; distilled water, 65 ml; and H₂O₂ (30% w/v), 10 ml, for 1 hr, is recommended.     

Enhancing antimicrobial properties of dyed and finished cotton fabrics

1,2,3-Benzothiazole-7-thiocarboxylic acid-S-methylester (commercially known as Actigard^® AM-87) was utilized to impart cotton fabric durable antimicrobial properties. Finishing treatment was carried out under a variety of conditions. The latter were included, effect of pH, concentration of antibacterial agents, curing temperature and curing time. The effect of fabric construction, mercerization, and dyeing with different dyestuff were also investigated. The study was also extended to investigate the technical feasibility of combining antimicrobial finishing treatment in question with other finishing treatment generally carried out on cotton fabric, like soft finishing and crease recovery finishing. The treated fabrics were monitored for antimicrobial properties before and after washing. The treated fabrics were also evaluated for the physio-mechanical properties like fabric tensile strength, elongation at break (or bursting strength for knitted fabric), wettability, crease recovery angle, whiteness index and roughness. Results obtained show that, the most appropriate conditions for treatment cotton fabric with Actigard^® are: padding the cotton fabric in aqueous solution containing 6% Actigard^® at pH 5 (adjusted using formic acid) then squeezed to wet pick up of 100%, dried at 80 °C for 5 min then cured at 100 °C for 150 s. The untreated cotton fabric did not show any antimicrobial activity towards Staphylococcus aureus or Escherichia coli. Treatment of cotton fabric with Actigard^® improves its antimicrobial properties towards S. aureus or E. coli. It is also observed that, treatment of cotton fabric with Actigard^® marginally decreases fabric tensile strength, elongation at break, roughness and WI, whereas; both wettability and crease recovery angle remain practically intact. This was observed whether the fabric was pre-mercerized or not.