Effect of emulsified lipid and saponified lipid on the enzyme desizing of starch and its mechanism.

To enhance the flexibility of starch film adhesion on yarns, sizing lipids (saponified lipid or emulsified lipid) must be added during the sizing process. However, different types of sizing lipids may have diverse combinations with starch to impact enzyme desizing. Therefore, this study investigated the effects of saponified lipid and emulsified lipid commonly used in warp sizing on the hydrolysis of starch. Additionally, the desizing efficiency and chain structure of desizing residues were analyzed. Experimental results demonstrated that the existence of saponified lipid or emulsified lipid led to a reduction in the degree of hydrolysis (1.1 % and 2.6 %, respectively) compared to the original corn starch. Notably, saponified lipid exhibited a relatively strong negative impact. Furthermore, the desizing efficiency decreased after adding emulsified lipid (1.2 %) or saponified lipid (2.9 %). Starch-lipid V-type complexes and physical hindrance could inhibit the enzyme desizing, resulting in a larger wavelength of maximum absorbance for desizing residues, along with higher molecular weight, z-average radius of gyration, and an increased proportion of long chains. The presence of saponified lipid significantly negatively influenced desizing, possibly due to the smaller particle size and propensity for complex formation with starch.

Fabrication of reversible bacteria-killing and bacteria-releasing cotton fabrics with anti-bacteria adhesion capacity for potential application in reusable medical materials.

Nowadays, more and more smart antibacterial materials have been prepared to meet some specific application area, and most of these materials have complex fabrication processes or incompatible biocompatibility. In this paper, a smart monomer that can switch between the form of quaternary ammonium salt and zwitterionic betaine was prepared and grafted onto cotton fabric. This finished cotton was smart too, it had nice antibacterial performance (99.89 % for E. coli and 99.97 % for S. aureus) in the form of quaternary ammonium salt, and it could release most of the attached bacteria when transferred to the form of zwitterionic betaine in PBS, and the form of zwitterionic betaine could converse back to the state of quaternary ammonium salt in HAC. Simultaneously, it was biocompatible in the form of zwitterionic betaine form. Furthermore, this smart material had nice function reproducibility after repeated transformations. In general, the smart antibacterial cotton could switch between bacteria-killing and bacteria-releasing reversibly, and had good biocompatibility and nice reproducibility, showing a potential application in reusable medical protective materials.

Reversible bacteria-killing and bacteria-releasing cotton fabric with anti-bacteria adhesion ability for potential sustainable protective clothing applications.

Multifunctional antibacterial surfaces are playing an essential role in various areas. Smart antibacterial materials equipped with switchable "bacteria-killing" and "bacteria-releasing" abilities have been created by scientists. However, most of them are either biologically incompatible, or complex fabricating procedures, or cannot prevent themselves from being attached by bacteria. In this work, a double-layer smart antibacterial surface was created easily by simple surface initiate atom transfer radical polymerization: the upper layer PSBMA provides anti-bacteria adhesion capacity, the NCl bond can show bacteria-killing ability and the under layer PNIPAM can exhibit bacteria-releasing property. Remarkably, the NCl bond can interconvert with the NH bond easily, which allows switching between bacteria-killing and bacteria-releasing. As a result, the functional cotton fabrics can resist about 99.66 % of bacteria attaching, kill nearly 100 % of attached bacteria after 5 min contacting and release about 99.02 % of the formerly attached bacteria. Furthermore, the functional cotton fabric kept excellent anti-bacteria adhesion ability (about 99.27 %) and bacteria-releasing capacity (about 98.30 %) after 9 cycles of re-chlorination. In general, a reversible "bacteria-killing" and "bacteria-releasing" cotton fabric was fabricated with well anti-bacteria adhesion capacity in a simple way, and this smart multifunctional cotton fabric shows a great potential application in reusable protective clothing.

Self-Assembly Properties and Aggregation Behavior of Amphiphilic Water-Dispersed Polyester with Different Contents of Sulfonate Groups in an Aqueous Solution.

Amphiphilic polymer water-dispersed polyester (WPET) has an important application value in the textile field. However, due to the potential interactions among water-dispersed polyester (WPET) molecules, the stability of their solution is susceptible to external factors. This paper focused on the self-assembly properties and aggregation behavior of amphiphilic water-dispersed polyester with different contents of sulfonate groups. In addition, the effects of WPET concentration, temperature, and Na+, Mg2+, or Ca2+ on WPET aggregation behavior were systematically investigated. The results show that compared with the low sulfonate group content of WPET, the high sulfonate group content of the WPET dispersion has higher stability with or without a high electrolyte concentration. In contrast, dispersions with low sulfonate group content are very sensitive to electrolytes and aggregate immediately at low ionic strength. WPET concentration, temperature, and electrolyte play important and complex roles in controlling the self-assembly properties and aggregation behavior of the WPET. The increase in WPET concentration can promote the self-assembly of WPET molecules. With the increase in temperature, the self-assembly properties for water-dispersed WPET are significantly reduced, resulting in enhanced stability. In addition, the electrolytes Na+, Mg2+, and Ca2+ in the solution can significantly accelerate the aggregation of WPET. This fundamental research on the self-assembly properties and aggregation behavior of WPETs can be used to effectively control and improve the stability of WPET solutions and provide guidance for the prediction of stability for WPET molecules not yet synthesized.

Plasticizer phthalate esters degradation with a laccase from Trametes versicolor: effects of TEMPO used as a mediator and estrogenic activity removal.

Phthalate esters (PAEs) are toxic and persistent chemicals that are ubiquitous in the environment and have attracted worldwide attention due to their threats to the environment and human health. Dimethyl phthalate (DMP) is a relatively simple structure and one of the most observed PAEs in the environment. This study investigated the degradation of the DMP using Trametes versicolor laccase and its laccase-mediator systems. The degradation effect of laccase alone on DMP was poor, while the laccase-mediator systems can effectively enhance the degradation efficiency. Within 24 h, 45% of DMP (25 mg/L) was degraded in the presence of 0.8 U/mL laccase and 0.053 mM 2, 2, 6, 6-tetramethylpiperidine-1-oxyl (TEMPO). A certain concentration (1 mM) of metal ions Al3+, Cu2+ or Ca2+ can positively promote DMP degradation with the laccase-TEMPO system. Moreover, the structure of PAEs also had a great influence on the degradation efficiency. Higher degradation efficiencies were observed when incubating PAEs with short alkyl side chains by the laccase-TEMPO system compared to that with long alkyl side chains. Additionally, the branched-chain PAEs had a better degradation effect than the straight-chain. The estrogenic activity of the DMP solution after reaction was much smaller than that of the original solution. Finally, transformation products ortho-hydroxylated DMP and phthalic acid were identified by GC-MS and the possible degradation pathway was proposed. This study verifies the feasibility of the laccase-TEMPO system to degrade PAEs and provides a reference for exploring more potential value of laccase.

Effects of exogenous proteins on enzyme desizing of starch and its mechanism.

Added protein to starch has abundantly applied to size the yarns. However, scarce information is available about the impact of proteins on the enzyme desizing of starch. Thus, the objective of this study was to explore the effect of corn gluten, soybean protein and bone glue on enzyme desizing and reveal the interference mechanism. The desizing efficiency of starch was detected after added proteins. The contact angle, swelling ability, protein content and structure of starch adhesion on desized yarn were measured to analyze the effect of protein on desizing. In addition, the binding forces between protein and starch were detected, and the inhibition mechanism was analyzed. Experimental results showed that desizing efficiencies of starch were decreased after adding the protein. Corn gluten had the strongest influence in hindering desizing due to the weakest promotion in the swelling of film and the stronger binding force between protein and starch, mainly through hydrophobic interaction and hydrogen bond. Improving the swelling ability of film and inhibiting the binding between starch and protein may be feasible ways to reduce the inhibition of protein on desizing.

Study on the cross-linking process of carboxylated polyaldehyde sucrose as an anti-wrinkle finishing agent for cotton fabric.

Sucrose was oxidized in a two-step oxidation reaction catalyzed by 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO)-laccase and sodium periodate (NaIO4). To generate carboxylated polyaldehyde sucrose (openSu) containing multiple aldehyde and carboxyl groups. The amount of TEMPO and laccase used, as well as the temperature and reaction time were optimized for the oxidation reaction. The successful combination of aldehyde and carboxyl groups of openSu with cellulose was achieved by changing the composition, ratio of the catalyst and the curing conditions. Thereafter, we analyzed the structural characteristics of openSu as well as the aldehyde and carboxyl group content using nuclear magnetic resonance carbon spectroscopy (13C NMR). We found that the optimal finishing conditions were a mixture of magnesium chloride and sodium hypophosphite at a mass concentration ratio of 16 g/L:4 g/L, and curing at 150 °C for 3 min followed by curing at 180 °C for 2 min. There was significant improvement in the anti-wrinkle performance of the openSu-finished fabric, with a wrinkle recovery angle of 258°, whiteness index of 72.1, and a tensile strength rate of more than 65%. We also studied the covalent crosslinking mechanism between openSu and the cotton fabrics.

Degradation of octylphenol polyethoxylates with a long ethoxylate chain using the laccase-mediated systems.

Alkylphenol polyethoxylates (APEOn) are the second-largest category of commercial nonionic surfactants, which are difficult to degrade naturally in the environment. This study examined the degradation of octylphenol polyethoxylate (OPEOn) by laccase and its laccase-mediated systems. The results showed that OPEOn was poorly degraded by laccase alone. 2, 2'-azino-bis [3-ethylbenzothiazoline-6-sulphonic acid] (ABTS), 1-hydroxybenzotriazole (HBT), and 2, 2, 6, 6-tetramethylpiperidine-1-oxyl (TEMPO) were selected as the redox mediators. Experimental results also indicated that 52.4% of the initial OPEOn amount was degraded by laccase in the presence of TEMPO. The degradation efficiency was analyzed using high-performance liquid chromatography. Furthermore, the structural characteristics of the degradation products were measured using matrix-assisted laser desorption/ionization-time of flight mass spectrometry and nuclear magnetic resonance spectroscopy, and it could be found that the laccase-TEMPO system could gradually shorten the ethoxylate chain by oxidizing the primary hydroxyl group of OPEOn, thereby degrading the OPEOn of the macromolecule into small molecules. The maximum of the ion peak distributions of OPEOn decreased from n = 8 finally down to 3. The novel enzymatic system introduced by this study will become a promising alternative method for high-efficiency APEOn conversion and had great potential value in wastewater treatment.

Preparation of PEG-modified wool keratin/sodium alginate porous scaffolds with elasticity recovery and good biocompatibility.

To improve mechanical properties of keratin (KR) porous scaffolds, we prepared a PEGylated keratin through thiol-ene click reaction. Several porous scaffolds were prepared by blending PEGylated keratin with sodium alginate (SA). The surface morphology, mechanical properties, and porosity of scaffolds were detailed studied at different KR/SA proportions. The results showed the content of SA had an effect on pore formation and mechanical properties. When the mass ratio of KR to SA was 2:1, the stress of yield point of the keratin porous scaffold reached 1.24 MPa, and also showed good deformation recovery ability. The PEGylated keratin porous scaffold had a high porosity and great cytocompatibility. Its' porosity is up to 81.7% and the cell viability is about 117.78%. This allows it to absorb the simulated plasma quickly (9.20 ± 0.37 g/g). In addition, the structural stability and acid-base stability of the keratin porous scaffold were also improved after PEGylation. Overall, the PEGylated keratin porous scaffold will be promising in tissue materials due to its great physical, chemical, and biological properties.

Green modification of cellulose-based natural materials by HRP-initiated controlled "graft from" polymerization.

Considerable attention has been focused on the application of natural cellulosic materials due to the cost-effectiveness, renewability, and biodegradability of cellulose. However, gaps between cellulose-based and petroleum-based materials still exist. In this study, a green, environmental modification method for cellulose by enzyme-initiated reversible addition fragmentation chain transfer (RAFT) graft polymerization was reported. First, the grafting of acryloyl chloride (AC) provided reaction sites on cellulosic fiber surfaces, followed by the enzymatic RAFT graft polymerization of acrylamide (AM). The grafting of well-controlled polyacrylamide (PAM) chains on the cellulosic material surface was verified by Fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectroscopy (XPS), and the controlled grafting ratio was also estimated. The transition of wetting behaviors after the modification of AC and PAM also provided evidence for successful grafting on cellulosic materials. In addition, this method can be well applied for the preparation of various functional cellulosic materials.

New strategy for grafting hydrophobization of lignocellulosic fiber materials with octadecylamine using a laccase/TEMPO system.

The enzymatic functionalization of lignocellulosic fibers using oxidoreductases was successfully achieved by targeting lignin moieties as grafting sites on the surface. In this study, a novel strategy for hydrophobization of lignocelluloses was investigated, which involved the laccase/TEMPO-mediated grafting of octadecylamine (OA) onto both lignin and cellulose components of jute fabrics. The results showed that OA monomers were successfully grafted onto jute fabric surface using the laccase/TEMPO system with the grafting percentage and efficiency values of 0.712% and 10.571%, respectively. The primary hydroxyl groups of cellulose were oxidized by laccase/TEMPO to carbonyl groups, which were then coupled with amino-contained OA monomers via Schiff base reaction. The phenolic hydroxyl groups of lignin were transformed by laccase to radicals, on which OA molecules were grafted via Michael addition reaction. Consequently, grafted jute fabrics showed a considerable increase in the surface hydrophobicity with a contact angle of 125.9° and a wetting time of at least 2 h. Furthermore, there was an acceptable decrease in the breaking strength of jute fabrics by 13.60%, and the color of fabrics turned yellowish and reddish. This eco-friendly enzymatic process provides a new strategy for grafting hydrophobization and even functionalization of lignocellulosic fiber materials using amino compounds.

Exploring the role of pullulan in the process of potato starch film formation.

It is well known that mixing pullulan (PUL) with starch can overcome the poor physical properties of pure starch based film. However, the mechanism of improvement of physical properties of starch film with PUL is yet to be clearly understood. The objective of this study is to investigate the effect of PUL in potato starch (PS) condensed matter solution and illustrate the mechanism improvement of physical properties of PS film by mixing with PUL. The moisture content of PS-PUL film decreased by 18.61 % because PS-PUL film chain-structure was denser than that of PS film. Based on the analysis of condensed matter solution, PUL could reduce the speed of PS chain movement and increase the flexibility of PS rigidity chains. Thus, tensile strength of PS-PUL film decreased by 20.34 % and elongation at break of PS-PUL film increased by 23.45 %. An increase in bending endurance by 49.51 % also illustrates that PUL improved the chain flexibility in the process of composite film formation. The present research provides a novel research route to understand the mechanism of hydrophilic colloids affecting the physical properties of starch film at molecular level. Also, the work provides a theoretical basis for the establishment of a correlation system between the microstructure and macroscopic properties.

Laccase-catalyzed polymerization of hydroquinone incorporated with chitosan oligosaccharide for enzymatic coloration of cotton.

Chitosan oligosaccharide (COS), a water-soluble carbohydrate obtained from chemical or enzymatic hydrolysis of chitosan, has similar structure and properties to non-toxic, biocompatible, and biodegradable chitosan. However, COS has many advantages over chitosan due to its low molecular weight and high water solubility. In the current work, COS was incorporated in the laccase-catalyzed polymerization of hydroquinone. The laccase-catalyzed polymerization of hydroquinone with or without COS was investigated by using simple structure of glucosamine hydrochloride as an alternative to COS to understand the mechanism of COS-incorporated polymerization of hydroquinone. Although polyhydroquinone can be regarded as the polymeric colorant with dark brown color, there is no affinity or chemical bonding between polyhydroquinone and cotton fibers. Cotton fabrics were successfully in-situ dyed into brown color through the laccase-catalyzed polymerization of hydroquinone by incorporating with COS as a template. The presence of COS enhanced the dye uptake of polyhydroquinone on cotton fibers due to high affinity of COS to cotton and covalent bonding between COS and polyhydroquinone during laccase catalysis. This novel approach not only provides a simple route for the biological coloration of cotton fabrics but also presents a significant way to prepare functional textiles with antibacterial property.

How starch-g-poly(acrylamide) molecular structure effect sizing properties.

The effect of starch-g-poly(acrylamide) (S-g-PAM) molecular structure on sizing properties has been investigated. S-g-PAMs were synthesized with the catalysis of horseradish peroxidase (HRP) and Fourier transform infrared (FT-IR) confirmed the acrylamide (AM) units had been successfully grafted on starch chains. Structural parameters, including degree of branching (DB), degree of substitution (DS) and grafting ratio (GR) were characterized by 1H nuclear magnetic resonance (1H NMR), and were correlated with sizing properties of apparent viscosity, adhesion to cotton yarns and film mechanical properties. The apparent viscosity of S-g-PAMs has no obvious correlation with DB and DS (or GR), as the amylose content of the native starch might have more influence on the viscosity of grafted starches. DS (or GR) values of grafted starches have a positive relationship with the tensile strength of sized cotton yarns and are negatively related with tensile strength of starch film. These results can provide guidance in the section of starch with improved sizing properties.

Exploring the mechanism of pullulan delay potato starch long-term retrogradation from the viewpoint of amylopectin chain motion.

Starch retrogradation is an inevitable process in the natural state caused by movement of starch chains. Therefore, the objective of this study was to explore the essence of starch long-term retrogradation from the viewpoint of amylopectin chain motion. The radius of gyration (Rg) and form factor (ρ) values of potato starch (PS) and PS with pullulan (PS-PUL) gradually increased during the retrogradation process. Furthermore, the conformation of molecular chains evolved from spherical to ellipsoidal to rod-like during starch retrogradation. Based on the analysis of condensed matter theory, these results illustrated that starch chains from gelatinization to retrogradation experienced shrinkage to extension. The values of Rg and ρ of PS-PUL were lower than PS, and the evolution of conformations showed that PUL delayed the long-term retrogradation of PS by decreasing the motion of amylopectin molecular chains to increase chain flexibility, and decrease the degree of entanglement and crosslinking. This study provides a novel method for characterizing starch retrogradation on the molecular level.

Graft modification of lignin-based cellulose via enzyme-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization and free-radical coupling.

In this study, a green approach combining enzyme-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization and free-radical coupling was developed for the modification of jute fiber, which is a typical lignin-based cellulose. Jute fiber surface was covered by rich amount of lignin, which offered great opportunities for further functional modification. The controlled polymerization of vinyl monomers, acrylamide (AM) or butyl acrylate (BA), was carried out by horseradish peroxidase (HRP)-initiated RAFT to form well-defined polymers with well-controlled molecular weights and structures. Enzymatic grafting by HRP occurred between the free radicals of well-defined polymers and free radicals of lignin on jute. Gel permeation chromatography (GPC) analysis indicated the alkyl chain length of polymers prepared via HRP-initiated RAFT polymerization was well-controlled. Other results of flourier transformed infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) revealed that well-controlled alkyl chains prepared via enzymatic catalysis were grafted on the exposed lignin of jute. The study explores a new and eco-friendly modification method for lignin-based materials with the controlled graft chain structure via two different catalysis with HRP.

Oxysucrose polyaldehyde: A new hydrophilic crosslinking reagent for anti-crease finishing of cotton fabrics.

For the first time, oxidized sucrose (oxysucrose) was used as a hydrophilic crosslinking reagent instead of conventional anti-crease reagents for cotton fabrics. In this research, the partial oxidization of sucrose with sodium periodate generated multiple aldehydes, which acted as multifunctional cross-linkers and endowed cotton fabrics with anti-crease and hydrophilic function. The results showed that the oxysucrose-treated cotton fabrics obtained the maximum crease recovery angle of 245°, durable press rating of 3.0, and whiteness index of 82.8. Importantly, the oxysucrose-treated samples showed better hydrophilicity that overcomes the hydrophobization deficiency of anti-creased cotton fabrics treated with previously reported dimethylol dihydroxy ethylene urea (DMDHEU), glutaraldehyde (GA), and 1, 2, 3, 4,-butanetetracarboxylic acid (BTCA). The etherification reaction between the aldehyde group of oxysucrose and the hydroxyl group of cellulose was investigated and the possible crosslinking and anti-crease mechanism was proposed.

Effect of pullulan on molecular chain conformations in the process of starch retrogradation condensed matter.

Starch retrogradation is an inevitable process in the natural state caused by motion of starch molecular chains. However, traditional starch retrogradation research methods cannot explain this process from the aspect of chain motion. Therefore, the objective of this study was to investigate the effect of pullulan (PUL) on potato starch (PS) retrogradation and analyze this using condensed matter theory. The entanglement concentration (ce) was determined by Ubbelohde viscometer. The ce values of PS and PS-PUL were 0.22 and 0.32 g/dL, respectively. Small-angle X-ray Scattering (SAXS) was used to obtain the radius of gyration (Rg) values and investigate conformation evolution of PS and PS-PUL in different solution concentrations ranging from extremely dilute to concentrated. The Rg values of PS increased by 38.7% upon transition from single chain (0.001 g/dL) to an entanglement state (0.22 g/dL) and the percent reduction of Rg was only 3.3% from entanglement state (0.22 g/dL) to stabilization (1 g/dL). The percent increase of Rg values of PS-PUL reached to 34.7% from extremely dilute (0.001 g/dL) to concentrated (1 g/dL) solutions. The trend of Rg indicated that ce played a major role in starch retrogradation. Dynamic light scattering (DLS) was used to acquire the hydrodynamic radius (Rh) which was a significant parameter to calculate form factor (ρ) by the ratio: ρ = Rg/Rh. The ρ values of PS-PUL were generally lower than those for PS. This result illustrated that PUL delayed the process of starch retrogradation by increasing flexibility of PS molecular chain. Furthermore, the ρ value of PS-PUL was higher than PS at 0.22 g/dL (ce of PS). This result illustrated that entanglement could decreased flexibility of molecular chain. The present research provides a novel research route for exploring the influence of hydrocolloids on starch retrogradation from the viewpoint of chain motion.

Controlled graft polymerization on the surface of filter paper via enzyme-initiated RAFT polymerization.

This study reports on eco-friendly graft polymerization approach for the modification of a cellulosic material via combination between enzymatic catalysis and reversible addition-fragmentation chain transfer polymerization (RAFT). Polyacrylamide (PAM) was polymerized on a cellulosic filter paper via horseradish peroxidase (HRP)-initiated RAFT polymerization. The results of grafting ratio, conversion, and pseudo-first-order kinetics were proved that the PAM graft polymerization on the filter paper followed RAFT rules. The results of Attenuated total reflection (ATR-FTIR), elemental analysis, and X-ray photoelectron spectroscopy (XPS) confirmed the presence of PAM in PAM-grafted filter paper. The results of water contact angle and Thermogravimetric analysis (TG) evidenced the change in the wetting properties and thermal performance, respectively of the treated filter paper. This work provides a new environmentally approach to graft polymerization on cellulosic materials.

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.