Bionic gradient scaffolds for osteochondral tissue engineering: construction strategies, interface optimization, gradient characterization, and controllability research

Osteochondral (OC) tissue faces significant challenges in defect repair due to its unique gradient characteristics. Bionic gradient scaffolds have been developed to address this issue, whose anisotropic three-dimensional structures can achieve gradual transitions in physical and chemical properties, providing innovative solutions for tissue regeneration. This review first focuses on the multidimensional gradient characteristics of natural OC tissue, including its composition, structure, performance, and metabolism, and provides an in-depth discussion of its significance for the design of biomimetic scaffolds. Second, it summarizes the current research progress on the construction strategy of gradient scaffolds. On this basis, this review innovatively proposes a systematic interface optimization strategy for discrete gradient scaffolds and summarizes the latest research progress on the gradient characterization and controllability of continuous gradient scaffolds. Finally, based on the current advances of research, this paper evaluates the main challenges facing this field and reviews the prospects in future development directions, providing new theoretical perspectives and technical routes for OC tissue engineering research.