Application and prospect of zinc oxide nanoparticle-enhanced biomimetic hydrogels in articular cartilage repair.

Articular cartilage injury is a common clinical condition in orthopedics. The avascular and aneural nature of the tissue results in extremely poor self-healing ability, which seriously impairs patients' motor function and quality of life. Current clinical treatment methods such as bone marrow stimulation, chondrocyte transplantation, and artificial joint replacement generally have limitations including the repaired tissue being primarily fibrocartilage, poor integration with host cartilage, and the need for secondary surgery, making them difficult to meet clinical needs. Hydrogels have become promising tissue engineering scaffolds for mimicking the natural cartilage extracellular matrix (ECM) due to their high water content, three-dimensional porous structure, and excellent biocompatibility. However, their defects such as insufficient mechanical strength, lack of biological activity, and antibacterial properties limit their clinical application and translation. Zinc oxide nanoparticles (ZnO NPs) are multifunctional bioactive materials that can enhance hydrogel mechanical stability and provide antibacterial, anti-inflammatory, and chondrogenic benefits through controlled Zn