The process of wound healing is often accompanied by bacterial infection, which is a serious threat to human health. The abuse of antibiotics in traditional therapy aggravates the resistance of bacteria and gradually reduces the therapeutic effect. Therefore, it is important to develop effective antibacterial dressings to promote wound healing and prevent infection. Photothermal therapy (PTT) is considered a quick and reliable method of suppressing bacterial infections without developing drug resistance. The unique network structure and high water retention of hydrogel help wound healing. Inspired by the hierarchical assembly of anisotropic structures across multiple length scales of muscles, herein a directional freezing-assisted salting-out method was used to prepare anisotropic MXene@PVA hydrogels. The hydrogel not only had excellent mechanical properties (stress up to 0.5 MPa and strain up to 800%), but could also be used for local hyperthermia of infected sites using an NIR laser (808 nm). Owing to the excellent photothermal properties of MXene, its main antibacterial mechanism is hyperthermia and the hydrogel showed broad-spectrum antibacterial activity against Gram-positive and Gram-negative bacteria (inhibition rates of Escherichia coli and Staphylococcus aureus were 98.3 and 95.5% respectively). In addition, it could effectively promote the proliferation of NIH-3T3 cells. In mouse wound models, the hydrogel was effective in inhibiting wound infection and promoting skin wound healing (the rate of wound closure was 98%). These results indicated that the MXene@PVA hydrogel, with high toughness and anisotropy properties, has the potential to be an excellent antibacterial wound healing dressing.

There is an increasing demand for more healthy and sustainable diets, which led to an interest in replacing synthetic colors with natural plant-based ones. Phycocyanin, which is commonly extracted from Spirulina platensis, has been explored as a natural blue pigment for application in the food industry. It is also used as a nutraceutical in food, cosmetic, and pharmaceutical products because of its potentially beneficial biological properties, such as radical scavenging, immune modulating, and lipid peroxidase activities. The biggest challenges to the widespread application of phycocyanin for this purpose are its high sensitivity to chemical degradation when exposed to heat, light, acids, high pressure, heavy metal cations, and denaturants. Consequently, it is of considerable importance to improve its chemical stability, which requires a thorough knowledge of the relationship between the structure, environment, and chemical reactivity of phycocyanin. To increase the application of this natural pigment and nutraceutical within foods and other products, the structure, biological activities, and factors affecting its stability are reviewed, as well as strategies that have been developed to improve its stability. The information contained in this article is intended to stimulate further studies on the development of effective strategies to improve phycocyanin stability and performance.

The consumption of fresh fruits and vegetables is restricted by the susceptibility of fresh produce to deterioration caused by postharvest physiological and metabolic activities. Developing efficient preservation strategies is thus among the most important scientific issues to be urgently addressed in the field of food science. The incorporation of active agents into a polymer matrix to prepare biodegradable active packaging is being increasingly explored to mitigate the postharvest spoilage of fruits and vegetables during storage. This paper reviews the composition of biodegradable polymers and the methods used to prepare biodegradable active packaging. In addition, the interactions between bioactive ingredients and biodegradable polymers that can lead to plasticizing or cross-linking effects are summarized. Furthermore, the applications of biodegradable active (i.e., antibacterial, antioxidant, ethylene removing, barrier, and modified atmosphere) packaging in the preservation of fruits and vegetables are illustrated. These films may increase sensory acceptability, improve quality, and prolong the shelf life of postharvest products. Finally, the challenges and trends of biodegradable active packaging in the preservation of fruits and vegetables are discussed. This review aims to provide new ideas and insights for developing novel biodegradable active packaging materials and their practical application in the preservation of postharvest fruits and vegetables. Graphical Abstract