Hydrogel materials have great application value in biomedical engineering. Among them, photocrosslinked hydrogels have attracted much attention due to their variety and simple convenient preparation methods. Here, we provide a systematic review of the biomedical-engineering applications of photocrosslinked hydrogels. First, we introduce the types of photocrosslinked hydrogel monomers, and the methods for preparation of photocrosslinked hydrogels with different morphologies are summarized. Subsequently, various biomedical applications of photocrosslinked hydrogels are reviewed. Finally, some shortcomings and development directions for photocrosslinked hydrogels are considered and proposed. This paper is designed to give researchers in related fields a systematic understanding of photocrosslinked hydrogels and provide inspiration to seek new development directions for studies of photocrosslinked hydrogels or related materials.

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In recent years, 3D printing has gradually become a well-known new topic and a research hotspot. At the same time, the advent of 3D printing is inseparable from the preparation of bio-ink. Natural materials have the advantages of low toxicity or even non-toxicity, there being abundant raw materials, easy processing and modification, excellent mechanical properties, good biocompatibility, and high cell activity, making them very suitable for the preparation of bio-ink. With the help of 3D printing technology, the prepared materials and scaffolds can be widely used in tissue engineering and other fields. Firstly, we introduce the natural materials and their properties for 3D printing and summarize the physical and chemical properties of these natural materials and their applications in tissue engineering after modification. Secondly, we discuss the modification methods used for 3D printing materials, including physical, chemical, and protein self-assembly methods. We also discuss the method of 3D printing. Then, we summarize the application of natural materials for 3D printing in tissue engineering, skin tissue, cartilage tissue, bone tissue, and vascular tissue. Finally, we also express some views on the research and application of these natural materials.

The development and application of polysaccharide materials are popular areas of research. Emerging polysaccharide materials have been widely used in tissue engineering fields such as in skin trauma, bone defects, cartilage repair and arthritis due to their stability, good biocompatibility and reproducibility. This paper reviewed the recent progress of the application of polysaccharide materials in tissue engineering. Firstly, we introduced polysaccharide materials and their derivatives and summarized the physicochemical properties of polysaccharide materials and their application in tissue engineering after modification. Secondly, we introduced the processing methods of polysaccharide materials, including the processing of polysaccharides into amorphous hydrogels, microspheres and membranes. Then, we summarized the application of polysaccharide materials in tissue engineering. Finally, some views on the research and application of polysaccharide materials are presented. The purpose of this review was to summarize the current research progress on polysaccharide materials with special attention paid to the application of polysaccharide materials in tissue engineering.

By exploring the spatial-temporal pattern changes of ecological land in Yangzonghai watershed of Yunnan Province, this paper obtained the quantity and spatial distribution of ecological land, which promoted the effective protection, rational utilization and sustainable development of ecological environment in the watershed. Using the data of 2005, 2010, 2015 and 2020, ArcGIS and Fragstats4.2 software were used to analyze the spatial and temporal patterns of ecological land use in the study area by using dynamic variation degree, transfer matrix and landscape pattern index. The ecological land in Yangzonghai watershed was mainly basic ecological land and auxiliary ecological land, which accounted for about 77% of the total study area. From 2005 to 2020, the ecological land showed a decreasing trend, with a total decrease of 798.61 hm2. From the perspective of ecological land transfer matrix, forest land, cultivated land, bare land and construction land are converted frequently. The increase of forest land was mainly from cultivated land and bare land. The sources of cultivated land increase were forest land and bare land. The increasing sources of construction land were cultivated land, bare land and forest land. The decreasing sources of forest land became bare land and cultivated land. The decreasing sources of cultivated land became forestland and construction land. According to the landscape pattern index, woodland, water area and farmland were the main landscape types in the study area. From 2005 to 2020, woodland, water area and cultivated land all showed a trend of fragmentation, and the patch geometry changed from simple to complex. However, on the whole, the connectivity of dominant patch types in the study area was good, and the landscape diversity and dominance were relatively stable although there were certain fluctuations. The quantity, transfer and landscape pattern of ecological land in Yangzonghai basin from 2005 to 2020 were analyzed. It is expected to provide data support and decision-making basis for ecological land protection and ecological security system construction in the watershed.