Bridging interfacial barriers: Integrated design of adhesives for intervertebral disc repair.

Intervertebral disc degeneration (IVDD) is a leading cause of chronic low back pain, yet current clinical interventions and biomaterials-based therapies remain largely palliative and fail to address the underlying structural deterioration of the degenerated intervertebral disc (IVD). A critical design criterion has been consistently overlooked: robust interfacial adhesion. Within the mechanically demanding and biochemically harsh environment of the degenerated IVD, therapeutic materials lacking stable tissue adhesion are highly susceptible to delamination, migration, and extrusion, ultimately compromising therapeutic efficacy and causing severe postoperative complications. In this Perspective, we propose that durable interfacial adhesion must be established as a central design standard for next-generation IVDD repair materials. We systematically analyze the multiscale barriers that impede effective adhesion in the degenerated IVD and classify them into four interrelated categories: hydration-mediated interfacial shielding, hostile microenvironmental conditions, mechanical mismatch-induced fatigue, and surgical operability constraints. Building upon these barriers, we further outline corresponding engineering strategies, including interfacial water management, chemical adaptation coupled with microenvironmental reprogramming, and dynamic biomechanical integration with enhanced fatigue resistance. Rather than pursuing adhesion as an isolated performance metric, we advocate that IVD adhesives should integrate stable adhesion with therapeutic bioactivity to maintain long-time retention and support tissue repair within the degenerated IVD. By reframing adhesion as a prerequisite rather than a secondary materials characteristic, this Perspective provides a conceptual guide for the development of bioadhesives used in the unique physiological and mechanical conditions of the IVD, ultimately advancing the therapeutic landscape for IVDD.