Advances in photocrosslinked natural hydrogel-based microspheres for bone repair

In recent years, the prevalence of bone diseases is showing an increasing trend, which is mainly attributed to the aging of the global population. However, bone repair and regeneration are still an unsolved problem in the treatment of bone diseases, which include a series of biological events. Photocrosslinked natural hydrogel-based microspheres (PNHMs) are spherical particles composed of photocrosslinked natural hydrogel components. Due to their morphology, injectability, and biocompatibility, PNHMs are widely used in tissue regeneration, particularly for bone defects. In this article, we review the available photocrosslinked natural materials for PNHMs, and then introduce their preparation methods. After that, we summarize the important advanced functionalities of PNHMs. For example, PNHMs can be loaded with different active ingredients to exert anti-inflammatory, antibacterial, and antioxidant effects, while also realizing lubrication due to their specific shape and size distribution. In addition, the function of capturing ions can be realized via coordination. When applied in bone tissue engineering, PNHMs can promote angiogenesis and osteogenesis, with great potential in the treatment of bone diseases. Finally, the challenges and prospects of PNHMs for bone repair are discussed.