Recent advances in nanomaterial-enabled functional hydrogels for sports injuries: from targeted therapy and tissue regeneration to closed-loop theranostics and clinical translation

The increasing prevalence of sports injuries has created an urgent need for therapeutic platforms capable of providing mechanical support, localized treatment, tissue regeneration, and real-time rehabilitation monitoring. Nanomaterial-enabled functional hydrogels have emerged as promising candidates because of their tissue-like physicochemical properties, tunable mechanical performance, high biocompatibility, and capacity to encapsulate and deliver diverse therapeutic cargos. The incorporation of nanozymes, inorganic nanoparticles, nanocarriers, conductive nanomaterials, and bioactive nanocomponents further enables hydrogels to regulate inflammatory and oxidative microenvironments, improve mechanical stability, enhance cellular responses, and achieve stimuli-responsive drug or gene delivery. Using a tissue-oriented framework across five representative sports-injury categories, this review integrates material design and therapeutic applications with a cross-cutting analysis of nanomaterial-enabled functions and the translational relevance of evidence from direct sports-relevant versus broader pathological models. We first discuss hydrogel matrix materials, chemical and physical crosslinking strategies, and essential properties, including injectability, adhesion, self-healing, fatigue resistance, biodegradability, and responsiveness to biochemical or external stimuli. We then highlight their therapeutic applications in superficial soft-tissue wounds, volumetric muscle loss, bone defects, articular cartilage damage, and tendon or ligament injuries, with particular emphasis on controlled drug delivery, immunomodulation, angiogenesis, stem-cell regulation, biomineralization, electrical stimulation, and tissue-interface reconstruction. Emerging hydrogel-enabled therapeutic technologies are further examined across increasing levels of system integration, from sensing and integrated theranostic platforms to feedback-controlled intervention, while distinguishing these systems from material-level stimulus-responsive therapy and recognizing that highly integrated closed-loop systems remain predominantly preclinical. Finally, key translational challenges related to long-term biosafety, dynamic mechanical and biochemical reliability, scalable manufacturing and quality control, sterilization and storage, regulatory complexity, and clinical validation are critically discussed. Future integration with advanced nanocarriers, flexible bioelectronics, data-driven material design, and individualized rehabilitation strategies may facilitate the clinical translation of functional hydrogels and the development of next-generation theranostic platforms for precision sports medicine.