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The most prevalent complication arising from skin injuries is bacterial infection, where pathogenic bacteria proliferate significantly at the wound site, leading to subsequent complications like septic shock and sepsis. Although antibiotics presently effectively manage wound infections caused by common bacteria, the escalating prevalence of antibiotic-resistant strains necessitates urgent novel approaches for addressing such infections. Here, we present CS9P1-RA, a dual functional hydrogel dressing, based on polyvinyl alcohol (PVA) matrix crosslinked through hydrogen bonding. CS9P1-RA combines chitosan (CS), a food-derived antibacterial agent, with the natural compound rosmarinic acid (RA) to specifically target skin injuries caused by MRSA. Computational and molecular biology assays illustrate RA's ability to selectively inhibit the activity of Staphylococcus aureus (S. aureus) serine/threonine phosphatase (Stp1), reducing the S. aureus pathogenicity. CS9P1-RA showcases exceptional antibacterial efficacy (MIC = 1 mg/mL) and demonstrates potency in reducing virulence (IC 50  = 7.424 μM on Stp1). Notably, it effectively curbs bacterial growth and accelerates wound healing in the mice model, thereby fulfilling the practical requirements for clinical applications. Moreover, the mechanical properties of CS9P1-RA ensure user comfort during treatment. This work introduces a fresh design paradigm for dressing materials, offering a promising solution for treating skin injuries inflicted by antibiotic-resistant bacterial infections., Competing Interests: Declaration of competing interest The authors declare that they have no conflicts of interest. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Informed consent was obtained from all participants included in the study., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In this work, a new glucose oxidase-N-succinyl chitosan (GOD-NSCS) nanospheres was prepared through the immobilization of glucose oxidase (GOD) on N-succinyl chitosan (NSCS) nanospheres. Compared to the free GOD, GOD-NSCS nanospheres demonstrated the excellent anti-Colletotrichum gloeosporioides activity with the EC 50 values of 211.2 and 10.7 μg/mL against mycelial growth and spores germination. The computational biology analysis demonstrated that the substrate presented the similar binding free energy with GOD-NSCS nanospheres (-27.64 kcal/mol) compared with the free GOD (-24.04 kcal/mol), indicating that GOD-NSCS nanospheres had the same oxidation efficiency and produced more H 2 O 2 . Moreover, the enzyme activity stability of GOD-NSCS nanospheres could be prolonged to 10 d. The cell membrane was destructed by the treatment of H 2 O 2 produced by GOD, leading to the cell death. In vivo test, GOD-NSCS nanospheres treatment significantly prolonged the preservation period of mangoes 2-fold. Collectively, these results suggested that GOD-NSCS nanospheres suppresses anthracnose in postharvest mangoes by inhibiting the growth of C. gloeosporioides and might become a potential natural preservative for fruits and vegetables., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The purpose of this study is to develop a green and safe chitosan-based preservative which can be applied in strawberry preservation. Chitosan (CS) was treated by 2,2,6,6-tetramethylpiperidine oxygen radical/laccase oxidation system (TEMPO/laccase oxidation system), which was mainly used to prepare TEMPO/laccase chitosan (TLCS). Furthermore, on this basis, the structure and performance of TLCS were also studied. The results showed that compared with CS, the solubility of TLCS improved, and the kinetic viscosity reduced significantly. Next, a cinnamaldehyde-TEMPO/laccase chitosan (CIN-TLCS) antibacterial agent was prepared by covalently combining the aldehyde group in cinnamaldehyde (CIN) and the amino group in CS. It was found that CIN combined with TLCS through covalent bonds, which changed the structure and crystallinity of TLCS. In addition, the total antioxidant capacity of CIN-TLCS also improved, which was necessary for the application of CIN-TLCS in extending shelf life. Cytotoxicity experiments showed that CIN-TLCS had no cytotoxicity. Furthermore, strawberries were used to explore the actual bacteriostatic and fresh-keeping effects of CIN-TLCS. The experiment found that CIN-TLCS could maintain the freshness of strawberries at room temperature (23 ± 1°C) for 5 days and had positive effects on strawberry color, loss-weight rate, hardness and pH. These results showed that CIN-TLCS could be used as a potential preserving agent for fruit storage. PRACTICAL APPLICATION: To obtain a green, safe and effective food preservative, chitosan (CS) was modified by a 2,2,6,6-tetramethylpiperidine oxygen radical/laccase oxidation system (TEMPO/laccase oxidation system) to get TEMPO/laccase chitosan (TLCS) and cinnamic aldehyde-TEMPO/laccase chitosan (CIN-TLCS). At the same time, the structure and antibacterial properties of TLCS and CIN-TLCS were analyzed, and their possibility as a new green and safe strawberry preservative was studied. Compared with oxazolidine, imidazole and triazole commercial drugs, CIN-TLCS has the advantages of low price, no pollution, no cytotoxicity and no drug resistance., (© 2021 Institute of Food Technologists®.)

Summary: Safe and suitable food preservatives can ensure food safety and reduce resource wastage. This paper focuses on the modification of chitosan (CS) using 2,2,6,6‐tetramethylpiperidine‐1‐oxyl radical (TEMPO)/laccase oxidation system and chitosanase. The experimental results showed that the aldehyde group content of the modified CS was increased by 83.3% and the water solubility increased by 4.5 times. In addition, the covalent binding with lysozyme (LSZ) also improved the inhibition effect and the diameter of the inhibition circle was increased by 3 mm. Applying the LSZ‐modified CS to the preservation of strawberries and Tremella fuciformis (T. fuciformis), it was found that the preservation time of strawberries could be extended by 2 days at room temperature, and the microbial spoilage of T. fuciformis was also inhibited. This study provided a CS derivative that could be used as a carrier of natural antibacterial agents, which increased application scope of CS and provided a basis for antimicrobial preservation of food. [ABSTRACT FROM AUTHOR]

The growing demand for bio-based materials for food packaging has stimulated the development of new environment-friendly films. The antibacterial films were prepared by adding nisin and different concentrations of Perilla essential oil (EO) to N-succinyl chitosan (NSC). Scanning electron microscopy, Fourier transform infrared spectrum, X-ray diffraction measurements and thermo stability analysis showed that nisin and EO dispersed in the NSC matrix. In addition, the composite films with nisin (N) and different concentrations of EO (EOx-NNSC) had good antioxidant and antibacterial activity against Staphylococcus aureus, Escherichia coli, Salmonella enteritidis and Pseudomonas tolaasii and were safe for use. Adding nisin and EO also improved the mechanical, water vapor barrier and optical properties of the films. The application of films to strawberries showed that the addition of N and EO to NSC films delayed the rapid decay of strawberries during storage. In conclusion, EOx-NNSC films can be used as a biodegradable and environment-friendly packaging material for food preservation. [ABSTRACT FROM AUTHOR]

The purpose of this study is to obtain a washable, nontoxic and safe green antibacterial preservation material that can be used for food preservation. Therefore, a water-soluble N -succinyl chitosan (NSC) was prepared by reacting succinic anhydride with chitosan, and lysozyme- N -succinyl chitosan (LSZ-NSC) was prepared using NSC loaded lysozyme (LSZ). The effect of NSC on lysozyme activity and antibacterial activity was studied. Lysozyme activity in LSZ-NSCs increased by 256% compared with the activity of free lysozyme, and bacteriostatic activity also increased, and increased significantly at low concentrations. The structure and stability of NSC and LSC-NSC were analyzed. The active group introduced by NSC was located on the C2–NH 2 group of chitosan. During the process of lysozyme loading, the secondary structure of lysozyme changed markedly, which may be one of the reasons for the change in lysozyme activity. Based to the characteristics of NSC and LSZ-NSC, these compounds were used as bacteriostatic materials in strawberry preservation. Both NSC and NSC-LSZ prolonged the shelf life of strawberry, and NSC-LSZ effectively extended the shelf life of strawberry by 3 days. This research provides a safe and feasible green bacteriostatic preservative material for the fresh storage of food. • A method for preparing green washable lysozyme-N-succinate chitosan is provided. • N-succinyl chitosan immobilization improved the activity of lysozyme. • Lysozyme-N-succinyl chitosan prolong the freshness of Strawberry for 3 days. [ABSTRACT FROM AUTHOR]

Fresh Tremella fuciformis is becoming more popular among consumers as an edible fungus, as it is more natural and nutritious than dried T. fuciformis. However, fresh T. fuciformis is susceptible to contamination by Burkholderia gladioli leading to deterioration in quality and safety. In this study, clove essential oil nanoemulsions (CNE) were prepared and then incorporated into chitosan coating (CSC) to develop a clove essential oil nanoemulsion/chitosan coating (CNE-CSC) for bacteriostatic and preservation of fresh T. fuciformis. The results showed that CNE-CSC significantly inhibited the growth of B. gladioli with the inhibition rate >85% when the concentration was 1.25 g/L and inhibited more than 85% of biofilm formation when the concentration was as low as 0.625 g/L. The inhibitory activity of CNE-CSC for the growth of B. gladioli directly lowered the expression of bongkrekic acid and then reduced the threat posed by bongkrekic acid to food safety. Moreover, in B. gladioli infection models, CNE-CSC treatment significantly prolonged the preservation of fresh T. fuciformis by preventing B. gladioli from infecting models. Therefore, CNE-CSC could be used as a safe, non-toxic, edible and new preservative coating for fresh T. fuciformis. • Clove essential nanoemulsion (CNE) was prepared. • CNE was incorporated into chitosan as antimicrobial coating (CNE-CSC). • CNE-CSC showed the high antibacterial activity against B. gladioli. • CNE-CSC extended the fresh T. fuciformis shelf-life to 9 days. • CNE-CSC improved the storage quality and safety of fresh T. fuciformis. [ABSTRACT FROM AUTHOR]