All-natural chitosan-based polyimine vitrimer with multiple advantages: A novel strategy to solve nondegradable plastic waste pollution.

The increasing amount of nondegradable petroleum-based plastic waste releases chemical hazards, posing a significant threat to the environment and human health. Chitosan, derived from marine wastes, is an attractive feedstock for the preparation of plastic replacement due to its renewable and degradable nature. However, in most cases, complex chemical modifications of chitosan or hybridization with chemicals from fossil resources are required. Herein, we present a high-performance chitosan-based polyimine vitrimer (CS-PI) through a mild and catalyst-free Schiff base reaction between chitosan and vanillin. The CS-PI were formed by integrating dynamic imine bonds into the polymer networks, resulting in superior thermo-processability and mechanical performances. The tensile strength and Young's modulus of the CS-PI films reached 38.72 MPa and 3.20 GPa, respectively, which was significantly higher than that of both commercial petroleum-based plastics and bioplastics. Additionally, the CS-PI films exhibited good light transmittance, self-healing ability, reprocess capacity, water resistance, and durability to various organic solvents. Moreover, the CS-PI films could be completely degraded under both acidic and natural conditions, enabling a sustainable circulation. Therefore, this work offers a new design strategy for developing all-natural environmentally friendly polymers as sustainable replacements for petroleum-based plastics, thus reducing the accumulation of nondegradable plastic waste.

Chemerin and IL-17 are potential predictors and Chemerin silencing alleviates inflammatory response and bone remodeling in chronic rhinosinusitis.

Chronic rhinosinusitis (CRS) is an inflammatory disease of paranasal sinuses. This study is formulated to explore the roles of pro-inflammatory factors Chemerin and interleukin-17 (IL-17) in CRS. Patients suffering from CRS without/with nasal polyps (CRSsNP/CRSwNP), along with volunteers, were recruited. CRS rabbit models were constructed by Staphylococcus aureus infection and rabbits were injected with lentiviral vectors of short hairpin RNA-targeting Chemerin (shChemerin), followed by micro-computed tomography (CT) scan. Levels of Chemerin and IL-17 were determined, and histopathological lesions were observed in subjects and CRS rabbits. Correlations between Chemerin/IL-17 level and Lund-Mackay/Lund-Kennedy scores of subjects and the predictive value of Chemerin or IL-17 for CRS were analyzed. In CRS patients and rabbits, inflammatory degrees and the level of Chemerin/IL-17 were increased in pathological tissues or plasma, while Chemerin silencing alleviated CRS symptoms of CRS rabbits. Chemerin and IL-17 were mainly located in the immune cells of pathological tissues and presented the positive correlation with Lund-Mackay/Lund-Kennedy score of CRS patients. Also, they showed high predictive value for CRS. Micro-CT scan uncovered that CRS rabbits had increased bone remodeling, which was alleviated by Chemerin silencing. Collectively, Chemerin and IL-17 are potential predictors and Chemerin silencing alleviates inflammatory response and bone remodeling in chronic rhinosinusitis.

Reconstruction of Cellulose Intermolecular Interactions from Hydrogen Bonds to Dynamic Covalent Networks Enables a Thermo-processable Cellulosic Plastic with Tunable Strength and Toughness.

Its excellent renewability and biodegradability make cellulose an attractive resource to prepare fossil-based plastic alternatives. However, cellulose itself exhibits strong intermolecular hydrogen bond (H-bond) interactions, significantly restricting the mobility of cellulose chains, thus leading to poor thermo-processing performance. Here, we reconstructed the intermolecular interactions of cellulose chains via replacing the original H-bonds with dynamic covalent bonds. By this, cellulose can be easily thermo-processed into a cellulosic plastic under mild conditions (70 °C). Through adjusting the chemical structure of dynamic covalent networks, the cellulosic plastic shows tunable mechanical strength (3.0-33.5 MPa) and toughness (43-321 kJ m-2). The cellulosic plastic also exhibits excellent resistance to water, organic solvent, acid solution, alkali solution, and high temperature (>400 °C). Moreover, it owns good chemical and biological degradability and recyclability. This work provides an effective method to develop high-performance cellulosic plastics for fossil-based plastic substitution.

A Biodegradable, Waterproof, and Thermally Processable Cellulosic Bioplastic Enabled by Dynamic Covalent Modification.

The growing environmental concern over petrochemical-based plastics continuously promotes the exploration of green and sustainable substitute materials. Compared with petrochemical products, cellulose has overwhelming superiority in terms of availability, cost, and biodegradability; however, cellulose's dense hydrogen-bonding network and highly ordered crystalline structure make it hard to be thermoformed. A strategy to realize the partial disassociation of hydrogen bonds in cellulose and the reassembly of cellulose chains via constructing a dynamic covalent network, thereby endowing cellulose with thermal processability as indicated by the observation of a moderate glass transition temperature (Tg  = 240 °C), is proposed. Moreover, the cellulosic bioplastic delivers a high tensile strength of 67 MPa, as well as excellent moisture and solvent resistance, good recyclability, and biodegradability in nature. With these advantageous features, the developed cellulosic bioplastic represents a promising alternative to traditional plastics.

Rapid transesterification of cellulose in a novel DBU-derived ionic liquid: Efficient synthesis of highly substituted cellulose acetate.

Cellulose acetate (CA) is one of the most important cellulose plastics that has demonstrated extensive applications in many areas. In search of a more sustainable and efficient way to prepare CA, we synthesized a novel ionic liquid, [DBUC8]Cl, based on the commonly used catalyst DBU (1,8-diazabicyclo[5.4.0]undecyquin-7-ene) in a simple manner. [DBUC8]Cl can dissolve cellulose more efficiently than the same type of imidazolyl ionic liquid, owing to the stronger alkalinity of DBU. It is noteworthy that highly substituted CA (DS = 2.82) was successfully synthesized via transesterification with alkenyl ester under mild conditions (80 °C, 40 min) without the addition of a catalyst in this solvent, which is superior to most of the reported work. Furthermore, we confirmed that the synthesized CA had good thermoplasticity, and a transparent cellulose acetate film (CAF) was obtained by hot pressing with a small amount of glycerol. Therefore, we propose a new DBU-derived ionic liquid, which may serve as a versatile platform system for producing cellulose-derived bioplastics more sustainably and efficiently.

Antimicrobial property of Pichia pastoris-derived natto peptide against foodborne bacteria and its preservative potential to maintain pork quality during refrigerated storage.

Pork spoilage caused by foodborne bacteria contamination always leads to substantial economic loss in the meat industry. The toxicity and drug resistance of chemical preservatives have raised public concerns about their safety and stability. In this study, natto peptide from Pichia pastoris was prepared using DNA recombinant technology. It showed an excellent antibacterial effect against Gram-positive and -negative bacteria, with minimum inhibitory concentrations (MICs) ranging from 6 to 30 µg/ml. Of note, natto peptide exhibited low cytotoxicity and hemolytic activity. The application of natto peptide on pork during refrigerated storage dramatically decreased the growth of Staphylococcus spp., Escherichia spp., and Pseudomonas spp. The bactericidal properties remained in force when natto peptide was used in pork models contaminated with artificial bacteria. Moreover, the application of natto peptide (90 µg/ml) inhibited the increase in pH variation and drip loss, decreased the generation of total volatile basic nitrogen (TVB-N) and thiobarbituric acid reactive substances (TBARS), and maintained a high sensory quality score during pork storage. These results implied that P. pastoris-derived natto peptide could extend the storage time of pork, and it has the potential to be a promising antiseptic biopreservative to replace chemical preservatives.

Thermo-processable chitosan-based plastic substitute with self-adaptiveness and closed-loop recyclability.

The increasing environmental burden generated by disposable plastic wastes makes the development of sustainable substitute materials an emergent task. As one of the most abundant bioresources, chitosan (CS) has been considered as a potential candidate for plastic substitution. Conventionally, CS-based materials are fabricated through a solution-processing procedure due to the high crystallinity of CS. Herein, we designed a CS-based material via integrating CS into the network of polyimine (PI), which shows thermomechanical processability similar to plastics. Strong interactions were achieved through dynamic imine bond and hydrogen bond and thus formed a thermo-processable dynamic composite network. These CS-based plastic substitutes exhibit exceptional mechanical performances, excellent thermal/chemical stability, and a series of self-adaptiveness, including re-healing, reprocessing and multi-layer laminating. Notably, CPs can be easily degraded and 100% recycled for the production of next-generation materials. This work provides an alternative route to produce green and sustainable biomass materials as a plastic substitute.