anyuan Yu

Hydrophobic surface functionalization of lignocellulosic jute fabrics by enzymatic grafting of octadecylamine

Enzymatic grafting of synthetic molecules onto lignins provides a mild and eco-friendly alternative for the functionalization of lignocellulosic materials. In this study, laccase-mediated grafting of octadecylamine (OA) onto lignin-rich jute fabrics was investigated for enhancing the surface hydrophobicity. First, the lignins in jute fabrics were isolated and analyzed in the macromolecular level by MALDI-TOF MS, (1)H NMR, (13)C NMR, and HSQC-NMR. Then, the surface of jute fabrics was characterized by FT-IR, XPS, and SEM. Subsequently, the nitrogen content of jute fabrics was determined by the micro-Kjeldahl method, and the grafting percentage (Gp) and grafting efficiency (GE) of the enzymatic reaction were calculated. Finally, the surface hydrophobicity of the jute fabrics was estimated by contact angle and wetting time measurements. The results indicate that the OA monomers were successfully grafted onto the lignin moieties on the jute fiber surface by laccase with Gp and GE values of 0.712% and 10.571%, respectively. Moreover, the modified jute fabrics via OA-grafting showed an increased wetting time of 18.5 min and a contact angle of 116.72°, indicating that the surface hydrophobicity of the jute fabrics increased after the enzymatic grafting modification with hydrophobic OA molecules.

Cellulase immobilization onto the reversibly soluble methacrylate copolymer for denim washing

Cellulase treatment of denim fabrics is an environmentally friendly way for producing desired worn look. In this work, the enzymatic treatments of the denim fabrics, i.e., bio-washing, using native cellulase and cellulase immobilized with reversibly soluble copolymer (Eudragit S-100), immobilized-cellulase, have been investigated. According to the analyses of the lightness (CIE L value), color strength (K/S value) and color variations, at a cellulase concentration level of 6% o.w.f., the denim fabrics treated with the immobilized cellulase showed decoloration and color effect close to the native cellulase. However, the immobilized cellulase treatment of the denim fabrics showed lower weight loss and considerably higher tensile strength than those treated with the native cellulase. Both the native and immobilized cellulases improved the crystalline indice and the apparent crystallite size of the fiber sample compared with the control ones. The amorphous portion of the cellulose suffered more hydrolysis by the native cellulase than the immobilized cellulase. Scanning electron microscope pictures (SEM) and digital pictures further indicated that the immobilized cellulase can efficiently remove indigo dyestuffs on the surfaces of the denim fabrics without the problem of excessive damage to the fibers.

Hydrophobic modification of cotton fabric with octadecylamine via laccase/TEMPO mediated grafting.

Hydrophobic cotton fabrics were prepared by grafting octadecylamine (ODA) onto cotton fiber surfaces via the laccase/2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) treatment. The cotton fibers were oxidized by laccase/TEMPO to introduce aldehyde groups, which reacted with the amino groups of ODA to form Schiff base. First, ODA was coupled to glucan, used as a model compound of cellulose. The results of FT-IR and MALDI-TOF mass spectroscopy prove the formation of a Schiff base between ODA and glucan. Moreover, the existence of ODA in the grafted cotton fibers was verified by ATR-FTIR, elemental analysis, X-ray photoelectron spectroscopy. Finally, the hydrophobicity of the ODA-grafted cotton fabrics was estimated. The surface hydrophobicity of the cotton fabrics increased after the enzymatic grafting reaction.

Effect of protease treatment on dyeing properties of wool fabrics for single bath

During the conventional process of dyeing for wool fabric, the most important problem is the damage to wool fiber and energy waste because of high temperature. In this paper, the effect of a commercial protease, Savinase 16L from Novozymes, on low temperature dyeing properties of wool fabric was studied. The results showed that after treatment with protease for 30 min at 50°C and pH 8.0, the exhaustion of the Acid Yellow 116 on wool fabric increased 11.11% and 8.58% by comparing with that on the control samples without protease treatment when dyeing at 80°C and 90°C, respectively. And the dye absorption at 90oC on protease pretreated wool fabric was almost the same as that with the conventional boiling dyeing procedure. A single bath process containing protease treatment at 50°C and pH 8 and dyeing at 90°C and pH 4 was investigated. The dyeing effect of wool fabric dyed with one‐bath process was nearly the same as that with the two‐bath method and conventional boiling dyeing process. The results suggest that protease treatment offers an option of a one‐bath dyeing process, replacing the water‐ and energy‐consuming two‐bath method and conventional dyeing process.

Covalent Immobilization of Catalase onto Regenerated Silk Fibroins via Tyrosinase-Catalyzed Cross-Linking

Regenerated silk fibroins could be used as medical scaffolds and carrier materials for enzyme immobilization. In the present work, tyrosinase enzyme was used for enzymatic oxidation of silk fibroins, followed by immobilization of catalase onto the fibroin surfaces through physical adsorption and covalent cross-linking as well. Spectrophotometry, SDS-PAGE, and Fourier transform infrared spectroscopy (FTIR) were used to examine the efficiency of enzymatic oxidation and catalase immobilization, respectively. The results indicate that tyrosine residues in silk fibroins could be oxidized and converted to the active o-quinones. Incubating silk fibroins with catalase and tyrosinase led to a noticeable change of molecular weight distribution, indicating the occurrence of the cross-links between silk fibroins and catalase molecules. Two different pathways were proposed for the catalase immobilizations, and the method based on grafting of catalase onto the freeze-dried fibroin membrane is more acceptable. The residual enzyme activity for the immobilized catalase exhibited higher than that of the control after repeated washing cycles. Meanwhile, the thermal stability and alkali resistance were also slightly improved as compared to free catalase. The mechanisms of enzymatic immobilization are also concerned.

Enzymatic processing of protein-based fibers

Wool and silk are major protein fiber materials used by the textile industry. Fiber protein structure-function relationships are briefly described here, and the major enzymatic processing routes for textiles and other novel applications are deeply reviewed. Fiber biomodification is described here with various classes of enzymes such as protease, transglutaminase, tyrosinase, and laccase. It is expected that the reader will get a perspective on the research done as a basis for new applications in other areas such as cosmetics and pharma.

Immobilization of cellulases on the reversibly soluble polymer Eudragit S-100 for cotton treatment

Cellulases can penetrate into the fiber, causing tensile strength loss of the cellulosic fibers or fabrics. To minimize the tensile strength loss, we have immobilized cellulases on Eudragit S‐100. The characteristics of covalent Eudragit cellulase were evaluated using gel filtration analysis and UV spectra. Gel filtration analysis revealed that the cellulases were covalently bound to the polymer. Covalent Eudragit cellulase was loaded with the enzyme of about 40% and had a relative activity about 80% at a Eudragit S‐100 concentration of 15 g/L. When cellulase is bound to the polymer, the solubility profile becomes similar to the one of Eudragit. In addition, the effects of the enzyme on the cotton yarns and fabric using cellulases have been investigated. Native and immobilized cellulases caused improvements in whiteness and wrinkle recovery angle of the fabric in comparison to the control samples. The bending stiffness results show that native and immobilized cellulase treated cotton fabric has an improved softness than the control samples. It was found that using the immobilized cellulase reduced the weight and tensile strength, because the hydrolytic attack is only limited to the surfaces of cotton fibers.

A novel approach for grafting of β-cyclodextrin onto wool via laccase/TEMPO oxidation

This study demonstrated a new enzymatic methodology to graft β-cyclodextrin onto wool. The primary hydroxyl groups in β-cyclodextrin were oxidized to aldehyde groups using laccase/2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), which reacted with the amino groups of wool to form Schiff bases. The effects of treatment conditions (treatment temperature, laccase dosage, TEMPO dosage, treatment time) on the aldehyde and carboxyl contents in β-cyclodextrin were studied. FTIR spectrum of oxidized β-cyclodextrin showed the presence of aldehyde and carboxyl groups. Results of MALDI-TOF mass spectroscopy confirmed the coupling of β-cyclodextrin to tyrosine, which was used as a model compound for wool. ATR-FTIR spectroscopy of the grafted wool confirmed the presence of β-cyclodextrin in grafted wool and the formation of a Schiff base between β-cyclodextrin and wool.

Jute/polypropylene composites: Effect of enzymatic modification on thermo-mechanical and dynamic mechanical properties

In this study, a high-performance composite was prepared from jute fabrics and polypropylene (PP). In order to improve the compatibility of the polar fibers and the non-polar matrix, alkyl gallates with different hydrophobic groups were enzymatically grafted onto jute fabric by laccase to increase the surface hydrophobicity of the fiber. The grafting products were characterized by FTIR. The results of contact angle and wetting time showed that the hydrophobicity of the jute fabrics was improved after the surface modification. The effect of the enzymatic graft modification on the properties of the jute/PP composites was evaluated. Results showed that after the modification, tensile and dynamic mechanical properties of composites improved, and water absorption and thickness swelling clearly decreased. However, tensile properties drastically decreased after a long period of water immersion. The thermal behavior of the composites was evaluated by TGA/DTG. The fiber-matrix morphology in the modified jute/PP composites was confirmed by SEM analysis of the tensile fractured specimens.

A study of surface morphology and structure of cotton fibres with soluble immobilized-cellulase treatment

Our previous studies have demonstrated that cotton fabrics treated with soluble immobilized-cellulase showed considerably lower degradation and higher retention of tensile strength than those treated with free cellulase. It is important to investigate the surface morphology and structure of cotton fibres for understanding the enzymatic degradation. In this study, the effects of the soluble immobilized-cellulase on the surface morphology and structure of cotton fibres were investigated. The ultrastructural changes in the fibre surfaces were inspected using Tapping-Mode Atomic Force Microscopy (TM-AFM) and scanning electron microscopy (SEM), and the results showed that the smooth surfaces could be obtained after the immobilized-cellulase treatment, and no obvious damage was observed on the fibre surfaces. The hydrogen bonds in the certain depth area beneath the fibre surface were investigated using Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy (ATR-FTIR) after the cellulase treatments. Furthermore, the result of fibre accessibility indicated that the hydrolysis occurring in the interior of the cotton fibres was limited during the immobilized-cellulase treatment. Crystalline index (CI) of the cotton fibres treated with free cellulase was slightly higher than that of fibres treated with immobilized cellulase.