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.

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.

Sensitive Micro-Breathing Sensing and Highly-Effective Photothermal Antibacterial Cinnamomum camphora Bark Micro-Structural Cotton Fabric via Electrostatic Self-Assembly of MXene/HACC.

Natural fabrics are gradually becoming the ideal substrate for flexible smart wearable devices due to their excellent moisture absorption, softness, and skin-friendliness. However, the bonding fastness of the conductive layer and the corresponding durability during service have not yet been well satisfied. In this report, we successfully prepared a smart wearable multifunctional protective cotton fabric with microbreathing monitoring and rapid-photothermal antibacterial abilities of Cinnamomum camphora bark microstructure, by combining chitosan quaternary ammonium salt (HACC) with MXene nanosheets through electrostatic self-assembly. Impressively, MXene nanosheets and HACC established a strong interaction using the electrostatic attraction, endowing the fiber surface with ordered nanosheets. Meanwhile, the fabric decorated with MXene/HACC retains its original characteristics of outstanding breathability and softness, and its conductivity exhibits noticeable stability in terms of resistances to oxidation, washing, various solvents, and long-term bending cycles. On the basis of the principle of adsorption and release of water molecules in the MXene multilayer structures, the MXene/HACC fabric could accurately monitor the physiological health activities of users according to their breathing frequency and depth. Benefiting from the local surface plasmon resonance (LSPR) effect, the MXene/HACC shows encouraging photothermal conversion ability, photothermal stability under long time irradiation, washing resistance, and cycle stability. In addition, the fabric achieved an antibacterial efficiency of nearly 100% against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus within 5 min under an irradiation intensity of 400 mW/cm2. More importantly, after 10 washes, the antibacterial efficiency against the two bacteria could still reach 99.975% and 99.98%, respectively. This multifunctional protective MXene/HACC cotton fabric is expected to play a unique role in the new generation of smart wearable microbreathing sensing and against to bacterial attack, and shows a broad application prospect.

Developing a Multifunctional Silk Fabric with Dual-Driven Heating and Rapid Photothermal Antibacterial Abilities Using High-Yield MXene Dispersions.

Two-dimensional material titanium carbide (Ti3C2Tx MXene) has been widely used for building diverse functional materials; however, the disadvantages of unsatisfactory yield and low concentration during the preparation process generally limit its large-scale promotion. In the present work, an MXene dispersion with enhanced yield (90%), high concentration (45 mg/mL), and excellent dispersibility was successfully prepared. Subsequently, the active MXene nanosheets were effectively in situ deposition onto the silk fiber by means of dip-coating, relying on van der Waals forces and hydrogen bonds. The obtained MXene-decorated silk fabric (MXene@silk) exhibits satisfactory electrical conductivity (170 mS/cm), excellent photothermal and electrothermal conversion properties, especially dual-drive energy conversion, rapid thermal responses, and long-term functional stability. Furthermore, UV protection factor of the fabric, and its antibacterial efficiency against Gram-negative Escherichia coli (E. coli) within 20 min of contact reach over 110 and 99%, respectively, demonstrating remarkable UV resistance and rapid photothermal antibacterial ability. Meanwhile, the fabric of MXene@silk still retains the original characteristics of breathability, softness, and skin-friendly properties compared to the untreated. The multifunctional fabric constructed through a facile and high-yield strategy shows a noticeable potential applying to smart textiles to meet people's multipurpose needs in the future.

Rapid Antibacterial Effects of Silk Fabric Constructed through Enzymatic Grafting of Modified PEI and AgNP Deposition.

Enzymatic antibacterial finishing is an eco-friendly alternative to develop functional silk-based materials. However, the low accessibility of tyrosine residues distributed in fibroin chains restricts the laccase-mediated functionalization of silk fibers (SF). To address this issue, a highly reactive p-hydroxyphenylacetic acid-modified polyethyleneimine (mPEI) was enzymatically grafted onto fibroin using laccase, aiming at constructing an antibacterial matrix of mPEI on the fiber surface. Subsequently, in situ deposition of silver nanoparticles (i.e., AgNPs) into the newly built mPEI network was performed to form a rapid antibacterial layer. The results indicated that laccase efficiently catalyzes the mPEI coupling, the zeta potential of SF-g-mPEI increases from -32 to 21.70 mV, and the silver content reaches 1.81% after AgNP embedment. Based on the combined two-step treatments, the obtained silk fabric exhibited excellent antibacterial abilities against two bacteria, including Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The antibacterial rates of both bacteria reached 99.9% within 30 min of contact, remaining over 99.9% within 18 h of contact even after washing 10 times. The present work provides an enzyme-mediated method for construction of silk fabric with durable and rapid antibacterial activity.

A facile strategy for the preparation of photothermal silk fibroin aerogels with antibacterial and oil-water separation abilities.

Curtains with light-to-heat conversion capacity can warm up a room under solar radiation and improve the thermal energy efficiency of buildings, thereby reducing energy consumption during winter. Herein, a photothermal silk fibroin aerogel is synthesized by freeze-drying and curing method, using silk fibroin (SF) as template and scaffold, copper sulfide nanoparticles (CuS NPs) as photothermal conversion material, polyethylene glycol (PEG) as plasticizer, and polydimethylsiloxane (PDMS) as the package agent. The results reveal that SF as the template may guide the growth of CuS NPs, and the introduction of PEG improves the flexibility of the prepared CuS@SF aerogel. The composite CuS@SF-PEG/PDMS aerogel not only preserves the initial characteristics of SF aerogel but also integrates hydrophobic, rapid antibacterial ability, high-performance photothermal conversion efficiency, and stable switching effect. The lightweight, self-heating SF-based aerogel can be applied to the preparation of home textiles such as smart curtains. Additionally, it can be used as absorbent for cleaning up viscous oil from water, which could expand the applications of SF-based biomaterials toward meeting the requirements of sustainable developments.

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.

Thiol-ene photoclick reaction: An eco-friendly and facile approach for preparation of MPEG-g-keratin biomaterial.

Wool keratin is a natural material with excellent properties, which is considered as scaffold biomaterial for tissue engineering. Polyethylene glycol can improve the mechanical properties of keratin materials because of its excellent biocompatibility and plasticity. In the present work, poly (ethylene glycol) methyl ether methacrylate (MPEGMA) was grafted onto keratin by thiol-ene photoclick reaction. The results of FTIR and SDS-PAGE verified the successful reaction between MPEGMA and keratin. Compared with the keratin, circular dichroism and XRD results showed that the ß-sheet ratio increased in MPEG-g-keratin. Additionally, it can be found that the exposure of keratin hydrophobic amino acids increased quickly and the micelle size became larger due to the introduction of MPEG from the results of fluorescence spectroscopy and particle size analysis. The MPEG-g- keratin was formed into a membrane to further study the application of the modified keratin. Compared with the keratin membrane, the flexibility and biocompatibility of modified keratin have been improved. This work provides an eco-friendly and facile approach for preparation of the keratin biomaterials.

Laccase-mediated construction of flexible double-network hydrogels based on silk fibroin and tyramine-modified hyaluronic acid.

Silk fibroin (SF) is a promising biomaterial with attractive properties, however, the practical applications of pure regenerated SF materials were severely restricted by their poor water retention and low elasticity. In this study, a tyramine-modified hyaluronic acid (mHA) was introduced to SF chains, followed by constructing double-network hydrogels via laccase-mediated crosslinking of SF and mHA. Mechanism of the enzymatic coupling reaction between SF and mHA was investigated using the model compounds. The morphology, mechanical property, and swelling behavior of SF-g-mHA hydrogel were evaluated. The results reveal that combination use of SF and mHA endowed the obtained hydrogels with high structural stability, improved mechanical properties and drug release behavior, which overcame the intrinsically poor formability of the pure fibroin hydrogels. This work provides a novel method to construct a double-network hydrogel with high flexibility and toughness, and expands the application range of the SF-based materials in biomedical fields.

Construction of a composite hydrogel of silk sericin via horseradish peroxidase-catalyzed graft polymerization of poly-PEGDMA.

Silk sericin (SS), which is one of the main components of Bombyx mori silk fibers, has attracted increasing attentions as functional biomaterials due to its diverse biological activities as well as excellent biocompatibility. However, the poor formability and weak mechanical properties of SS materials severely limit their practical applications in biomedical field. To address this issue, in this study poly(ethylene glycol)dimethacrylate (PEGDMA) modified sericin were prepared by graft polymerization of poly-PEGDMA (pPEGDMA) onto sericin chains in the presence of horseradish peroxidase and hydrogen peroxide under mild condition. The composite hydrogels obtained from the modified SS not only exhibit much improved formability and excellent mechanical properties, but also high possess porosity and swelling ratios up to 63 and 1,250%, respectively, at the optimized formulation. Moreover, the composite hydrogels also reveal sustained drug release behavior and acceptable cytotoxicity, which endow them with vast application as biomaterials. It is envisioned that the method presented in this study would expand the application of SS in biomedical filed.

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.

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.

Biomimetic mineralization behavior of COS-grafted silk fibroin following hexokinase-mediated phosphorylation.

Silk fibroin (SF) has potential applications in the biomedical field because of its excellent mechanical properties and biocompatibility. In the current study, chitooligosaccharide (COS) was enzymatically grafted onto SF using laccase. Subsequently, COS-grafted SF (SF-g-COS) was treated enzymatically in the presence of hexokinase and Mg-chelated adenosine triphosphate (ATP), so as to introduce phosphate groups onto the fibroin chains and promote the deposition of hydroxyapatite (HAp) during in situ biomimetic mineralization. The efficacy of phosphorylation and biomimetic mineralization of the SF-g-COS was evaluated by means of HPLC, MALDI-TOF MS, FTIR, XRD and EDS-Mapping. The results indicate that hexokinase has the capability to catalyze the phosphorylation of COS, resulting in an increase in the quantity of phosphorus in the SF-g-COS. Following mineralization of the phosphorylated SF-g-COS, a greater number of mineral phases were detected on its surface, accompanied by a higher content of calcium and phosphorus compared with other specimens. Cell viability tests using NIH/3T3 cells and cellular adhesion potential with MG-63 cells indicated that the fibroin-based biocomposite exhibited acceptable biocompatibility and superior cellular adhesion properties. The present study describes a novel method for preparation of fibroin/HAp biocomposites for bone tissue engineering.

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.