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Quaternized chitosan (QCS)-based films are garnering considerable attention owing to their multifunctional properties; however, their inherent hydrophilicity limits their application. In this study, a fluorine-free superhydrophobic surface for QCS-based film was fabricated using an easy and effective method. The film with hierarchical micro/nano structures (MN-surface) was fabricated by combining the template and spray methods. After modification with polydimethylsiloxane, the MN-surface showed excellent superhydrophobicity, with a water contact angle of 165.7° and a sliding angle of 4.2°. The air cushions captured by the hierarchical micro/nano structures reduced the contact area between water droplets and the MN-surface, giving it excellent self-cleaning ability. Additionally, the microstructures acted as a protective layer for the nanostructures, protecting them against damage during mechanical wear. Thus, the MN-surface exhibited remarkable mechanical robustness against sandpaper abrasion, tape peel-off, bending, stretching, and water flow impact. More importantly, it showed an excellent anti-adhesion effect on bacteria, thereby further lowering the risk of bacterial invasion. Consequently, the superhydrophobic QCS-based film opens up new possibilities for its application in diverse fields. [Display omitted] • The robust superhydrophobic quaternized chitosan-based film was prepared. • The surface exhibits outstanding adhesion properties and self-cleaning ability. • The formed hierarchical micro/nano structures can enhance its mechanical stability. • The surface shows good resistance to high-speed jets and continuous water flow. • The surface has significantly reduced bacterial adhesion by 95.2 %. [ABSTRACT FROM AUTHOR]

[Display omitted] • Directional freeze-drying technology was applied to the preparation of dressings. • The double cross-linked effect enhanced the strength of the dressings. • Aligned channels allowed anisotropic dressings to absorb exudate effectively. • This dressing could significantly accelerate diabetic wound healing. Excessive biofluid around wounds can cause infection and prevent healing. In this study, an anisotropic quaternized chitosan (QC)/sodium alginate (AL)-based aerogel wound dressing was prepared via a directional freeze-drying technique inspired by the channel structure used for water transport in trees. The aligned channels provided the dressing with self-pumping ability, allowing it to rapidly and completely remove biofluids and absorb biofluids up to 1292.5 % of its own weight. To enhance the strength of the dressing, a double cross-linked network was constructed based on the QC-AL electrostatic attraction and AL-Ca2+ chelation interaction. The axial compressive strength of the double cross-linked dressing reached 207.3 kPa (ε = 50 %). In addition, the dressing exhibited strong conductive properties (conductivity = 13.0 S/m), antioxidant activities [reactive oxygen species (ROS) scavenging ability = 88.0 %], and hemostatic characteristics (blood coagulation index = 1.8 %). The dressing also exhibited powerful antibacterial performance, exhibiting over 98.0 % inhibition of E. coli and S. aureus. Experiments on diabetic mouse models revealed that the dressing considerably promoted wound healing. On day 3, the wound healing rate was 96.7 % faster in the QAC group than in the gauze group. Therefore, the developed dressing may have great potential for chronic wound care. [ABSTRACT FROM AUTHOR]

[Display omitted] • A fully degradable chitosan-based composite film was prepared by casting method. • Four common plant fibers were successfully used to enhance the properties of films. • The films exhibited excellent mechanical, waterproof, and thermal properties. • Their basic performance indicators were favorable as food packaging materials. To provide a fully degradable food packaging film with excellent performance, a chitosan (CS)-based film containing micron-sized plant fibers was prepared by the casting method. With the addition of different plant fibers—wheat straw fiber (WF), maize straw fiber (MF), rice straw fiber (RF), and sisal fiber (SF), a significant improvement in mechanical, water resistance, water vapor barrier, and thermal properties was observed. By comparison, the most significant enhancement effect was observed in CS/SF-based film. The tensile strength and elongation at break of this film were 58.44 MPa and 14.42%, respectively. Moreover, it exhibited excellent properties such as the highest water contact angle (118°), a moisture absorption rate of 5.14%, a low water vapor transmission rate (110.73 g·m-2·d-1), and high thermal stability. Considering the sustainability and attractive physical properties, the improved films showed great potential for food packaging. [ABSTRACT FROM AUTHOR]

In the field of medical research, the development of safe and effective wound dressings is a continuous goal. Chitosan (CS) is highly sought after because of its unique biocompatibility, biodegradability, antibacterial, and healing-promoting properties. The CS molecule has a significant number of active amino and hydroxyl groups; thus, making substitutions and creating derivatives with varied biochemical properties are relatively straightforward processes. This review addresses the range of functions performed by CS and its derivatives in wound care, such as haemostasis, antibacterial, antioxidant, and wound healing. Furthermore, it summarises the various types of CS-based dressings, their performance features and applications. Finally, the future directions of CS-based dressings are proposed. [Display omitted] [ABSTRACT FROM AUTHOR]

To solve the problem of environmental pollution caused by plastic food packaging films, a biodegradable chitosan-based film containing micro ramie fibre and lignin was prepared by the casting method. With the addition of different ratios of ramie fibre and lignin to the chitosan matrix, a significant improvement in mechanical, water resistance, thermal, and antioxidant properties was observed. The addition of 20 wt% ramie fibre increased the tensile strength by 29.6%. Moreover, the addition of 20 wt% of lignin increased the antioxidant activity by 288%, and reduced the water absorption by 41.2%. However, due to their high pyrolysis temperatures, there was little difference between ramie fibre and lignin in improving the thermal stability. Finally, this study compared the food preservation effects of composite films and PE films. The application evaluation results showed that the composite films were more effective. Overall, the chitosan-based films showed great potential for food packaging. [Display omitted] • Eco-friendly chitosan-based composite film was prepared by casting method. • Ramie fibre was used for the first time to reinforce chitosan-based film. • Ramie fibre reinforced the tensile strength and thermal stability of film. • Lignin enhanced the water resistance, antioxidation and thermal stability of film. • The chitosan-based composite film had great potential for meat packaging. [ABSTRACT FROM AUTHOR]

The poor performance and high cost of the starch-sisal fibre composites with open-cell structures prevent their usage as biodegradable biomass to replace plastics. Therefore, inorganic fillers [talcum powder (TP), CaCO 3 (CC)] and a bio-filler [eggshell powder (EP)] were added, and the resulting mechanical properties, water resistance, thermal stability and biodegradation characteristics were compared. Results show that the tensile strength of the EP-composite increases by 34% and the compressive strength of the CC-composite increases by 69% when compared with those of the non-filler (NF) composite. The mechanical properties of the composites improved because of the reduction of starch crystallinity and the formation of new hydrogen bonds. The EP-composite offered optimal cushioning owing to its uniform and dense open-cell structures. Besides, the CC- and EP-composites offered better thermal stability. The composites with fillers were more waterproof than the NF-composite (by approximately 33%). After conducting biodegradability tests for 30 days, the EP-composite lost 67% of its mass, which was more than those associated with the TP- and CC-composites and can be attributed to the presence of organic matter in the EP-composite. These results demonstrate the potential of EP to replace CC and TP for reinforcing the starch-fibre composites with open-cell structures. Unlabelled Image • A filler-reinforced rapidly degradable starch-fibre composite with open-cell structures was prepared. • Both bio-fillers and inorganic fillers can improve the mechanical properties, thermal stability and water resistance. • Bio-fillers were advantageous for rapid biodegradation. • Bio-fillers (eggshell powder) have the potential to replace inorganic fillers (talcum powder and CaCO 3). [ABSTRACT FROM AUTHOR]

Enteromorpha prolifera belonging to the chlorophyta phylum is the main pollutant of "green tide", and propagates rapidly in recent years. However, there is almost no high-value enteromorpha treatment method at present. This study aimed to extract cellulose nanocrystals (CNC) from enteromorpha and prepare the CNC reinforced films based on alginate, carrageenan and shellac for food packaging. The effects of alginate, κ-carrageenan, cellulose nanocrystals and glycerin on the CNC reinforced alginate/carrageenan films (AC films) properties were studied systematically in this work. The results showed that the mechanical properties, swelling properties, and barrier properties of the AC could be adjusted by the concentrations of the different components. In addition, response surface methodology (RSM) was used to optimize the formula of the AC used for food packaging according to the requirements of the practical application. Furthermore, in order to further improve the food packaging capacity of the composite films, shellac was added to the optimized alginate/carrageenan films (OAC films) to obtain the shellac optimized alginate/carrageenan films (SOAC films). Finally, the OAC films and SOAC films showed excellent properties to extend the storage time of chicken breast and cherry tomatoes in the food storage experiment. • Enteromorpha pollutes the environment and is the main pollutant of "green tide". • Sodium alginate and κ-carrageenan can be used to prepare the composite films. • Cellulose nanocrystals obtained from enteromorpha could reinforce the composite films. • The composite films with shellac have great potential for food packaging. [ABSTRACT FROM AUTHOR]

Excessive exudation from the wound site and the difficulty of determining the state of wound healing can make medical management more difficult and, in extreme cases, lead to wound deterioration. In this study, we fabricated a pH-sensitive colorimetric chronic wound dressing with self-pumping function using electrostatic spinning technology. It consisted of three layers: a polylactic acid-curcumin (PCPLLA) hydrophobic layer, a hydrolyzed polyacrylonitrile (HPAN) transfer layer, and a polyacrylonitrile-purple kale anthocyanin (PAN-PCA) hydrophilic layer. The results showed that the preparation of porous PLLA fiber membrane loaded with 0.2 % Cur was achieved by adjusting the spinning-related parameters, which could ensure that the composite dressing had sufficient anti-inflammatory, antibacterial and antioxidant properties. The HPAN membrane treated with alkali for 30 min had significantly enhanced liquid wetting ability, and the unidirectional transport of liquid could be achieved by simple combination with the 20 um PCPLLA fiber membrane. In addition, the 4 % loaded PCA showed more obvious color difference than the colorimetric membrane. In vivo and ex vivo experiments have demonstrated the potential of multifunctional dressings for the treatment of chronic wounds. [ABSTRACT FROM AUTHOR]

Starch and plant fibers are abundant natural polymers that offer biodegradability, making them potential substitutes for plastics in certain applications, but are usually limited by its high hydrophilicity, and low mechanical performance. To address this issue, polylactic acid (PLA) is blended with cellulose and chitosan to create a waterproof film that can be applied to starch-fiber foaming biodegradable composites to enhance their water resistance properties. Here, plant fibers as a reinforcement is incorporated to the modified starch by foaming mold at 260 °C, and PLA based hydrophobic film is coated onto the surface to prepare the novel hydrophobic bio-composites. The developed bio-composite exhibits comprehensive water barrier properties, which is significantly better than that of traditional starch and cellulose based materials. Introducing PLA films decreases water vapor permeability from 766.83 g/m2·24h to 664.89 g/m2·24h, and reduce hysteresis angles from 15.57° to 8.59° within the first five minutes after exposure to moisture. The water absorption rate of PLA films also decreases significantly from 12.3 % to 7.9 %. Additionally, incorporating hydrophobic films not only enhances overall waterproof performance but also improves mechanical properties of the bio-composites. The fabricated bio-composite demonstrates improved tensile strength from 2.09 MPa to 3.53 MPa. [ABSTRACT FROM AUTHOR]

The diverse properties reported for starch-based materials indicate their potential for use in the preparation of biodegradable flexible actuators. However, their natural brittleness and lack of durability after modification limit their practical application. Therefore, we propose a strategy for preparing flexible starch-based composites. The results of macro/micro property characterizations and molecular dynamics simulations indicated that using starch, maleic anhydride, and stearic acid (SA), the mobility of the starch chains was enhanced and retrogradation was inhibited through the synergistic effects induced by chain breaking, complex formation with SA, and esterification of the starch molecules. In addition, the elongation at break of the modified starch (MS) reached 2070 %, and considerable ductility (>1000 %) as well as well-complexed structure were maintained after six months. Furthermore, the MS was able to undergo self-healing after fracture or a temperature-controlled stiffness transition. Moreover, it underwent complete degradation in soil within 30 d. Finally, an actuator was prepared by doping the MS with nano-Fe 3 O 4 particles to realize a dual magnetic and optical response. Dynamic monitoring was also achieved based on the electrical signal, thereby demonstrating the broad application scope of this material in the development of biodegradable flexible actuators. [Display omitted] [ABSTRACT FROM AUTHOR]

Unlike thermoplastic petroleum-based materials, starch-based materials rely on aqueous systems but are incapable of hot melting, resulting in low processing efficiency and limited large-scale industrial applications. In this study, the combination of α-amylase liquefaction and urea plasticization was used for the first time to obtain enzymatic thermoplastic starch (ETPS) for hot melting by changing the molecular chain of starch. ETPS showed an apparent hot melting phenomenon when heated below 200 °C. Differential scanning calorimetry revealed that heat absorption peaks were obviously reduced, and the hot melting phenomenon occurred easily depending on the combination of enzymatic hydrolysis and plasticization. Dynamic mechanical analysis indicated that the combined modification effectively increased the number of freely movable chains. The red shift of -OH stretching vibration peaks indicated the formation of strengthened hydrogen bonds in ETPS. X-ray diffraction showed that the crystallinity of ETPS was reduced to 5.68 %, effectively reducing the regenerative phenomenon. Gel permeation chromatography revealed that the molecular weight of ETPS decreased, and the entanglements between molecular chains were reduced. A tensile test showed that the elongation at break of ETPS was as high as 235.29 %, which was much higher than those of enzymatic hydrolysis starch and thermoplastic starch. [Display omitted] [ABSTRACT FROM AUTHOR]

Through a single-sided cavity free-form foaming process, composites with open cell structures similar to wood cells were obtained by using corn starch, pulp fiber, and sisal fibers, which was used as the middle layer of the sandwiched composites. Afterwards, more hydrophobic lignin-containing nanocellulose fibrils from pine bark were coated on the surfaces of the open cell composites by high-pressure gun spraying, simulating the bark of wood to impart barrier property to the final product. The water barrier, mechanical property, apparent density, heat insulation, and biodegradability of the sandwich structured bio-composites were characterized. Experimental results indicated that the water contact angle on the surface of the bio-composite was as high as 92°. The apparent density of the bio-composite was very low, at 0.107 g/cm3. The tensile strength of the bio-composites reached 5.3 MPa. After conducting biodegradability tests in soil for 60 days, the bio-composites lost 87 % of its mass. • A novel bio-composite with sandwich structure was developed by using crops sources. • Single-sided cavity free-form foaming method was able to generate uniform sized cell. • The bio-composite was being easily molded into versatile complex shapes. • The bio-composite was hydrophobic and lightweight, with excellent barrier properties. [ABSTRACT FROM AUTHOR]

Antibacterial hemostatic medical dressings have become feasible solutions in response to the challenging wound-healing process. In this study, a novel fiber-type medical dressing with excellent breathable, antibacterial, and hemostatic qualities was created using sodium alginate (SA), microcrystalline cellulose (MCC), polyvinyl alcohol (PVA), and Euphorbia humifusa Willd (EHW) based on microfluidic spinning technology, and the properties of the dressing were characterized. The orthogonal test demonstrates that PVA and MCC can enhance the mechanical properties of the fiber, which is a crucial requirement for fiber assembly to form the dressing. Moreover, the presence of EHW enhances the dressing's antibacterial and hemostatic qualities. The dressings have been proven to have potent antibacterial and hemostatic properties as well as the ability to considerably speed up wound healing and skin tissue regeneration in the in-vitro and in-vivo tests. In conclusion, this innovative fiber-type medical dressing containing SA, MCC, PVA, and EHW has enormous potential for managing wounds caused by bacteria. [ABSTRACT FROM AUTHOR]

Starch is regarded as one of the most promising sustainable materials due to its abundant yield and excellent biodegradability. From the perspective of practical engineering applications, this paper systematically describes the development of starch-based bio-composites in the past decade. Packaging properties, processing characteristics, and current challenges for the efficient processing of starch-based bio-composites are reviewed in industrial packaging. Green coatings, binders, adsorbents, flocculants, flame retardants, and emulsifiers are used as examples to illustrate the versatility of starch-based bio-composites in chemical agent applications. In addition, the work compares the application of starch-based bio-composites in conventional spinning with emerging spinning technologies and describes the challenges of electrostatic spinning for preparing nanoscale starch-based fibers. In terms of flexible electronics, the starch-based bio-composites are regard as a solid polymer electrolyte and easily modified porous material. Moreover, we describe the applications of the starch-based gels in tissue engineering, controlled drug release, and medical dressings. Finally, the theoretical input and technical guidance in the advanced sustainable engineering application of the starch-based bio-composites are provided in the work. [Display omitted] [ABSTRACT FROM AUTHOR]

Wheat straw is a potentially natural material for production of bio-composites due to its chemical composition. Lignin, cellulose and hemicellulose are closely connected in wheat straw and difficult to separate for nano-lignocellulose in high valuable application. The work presented a clean and simple way to prepare biodegradable nano-lignocellulosic membrane with high mechanical strength and water barrier property using nano-lignocellulose derived from wheat straw. Wheat straw was soaked in aqueous solution of urea at 90 °C for 24 h and fibrillated with boiling to obtain urea treated nano-lignocellulose (UNLC). Moreover, starch soluble (SS) latex was mixed with the UNLC slurry for binding the reinforcement for preparing the novel membrane (UNLC/SS). High speed centrifugation realized stratification of the chemical composition from wheat straw. Waxy and lignin as hydrophobic component was located at the surface of the developed membrane, which improved the water barrier property of the membrane. Water contact angle of the lignocellulosic membrane was beyond 110°. The hydrogen bond formation between the starch and cellulose increased the mechanical property of the novel biodegradable membrane. The tensile strength of the nano-lignocellulosic membrane increased from 7.6 MPa to 27.4 MPa. As the high strength, hydrophobic, transparent, biodegradable performance, the bio-composite membrane has many potential industrial applications. • A biodegradable membrane with high strength, and hydrophobic property was developed. • Layered structure occurred after high-speed centrifugation for hydrophobic surface. • Water contact angles of the novel composite membrane reached 110°. • The tensile strength of the composite membrane increased from 7.6 MPa to 27.4 MPa. [ABSTRACT FROM AUTHOR]