An Iron Disulfide‐Decorated Polymeric Carbon Nitride Integrated Photocatalytic Irrigation System Promotes Cartilage Repair via Transient H 2 O 2 ‐Mediated Immune Regulation

ABSTRACT Acute inflammation and necrosis in the temporomandibular joint (TMJ) hinder cartilage repair by disrupting immune–chondrocyte crosstalk and reactive oxygen species (ROS) homeostasis. Photocatalytic production of hydrogen peroxide (H 2 O 2 ) offers a promising approach for reconstituting the local microenvironment by debriding and healing damaged tissue. However, achieving high catalytic activity and selectivity for efficient and controllable ROS regulation remains challenging. Herein, we developed an iron disulfide (FeS 2 )‐decorated polymeric carbon nitride (PCN‐FeS 2 ) composite as an efficient visible‐light–driven photocatalyst for controlled H 2 O 2 generation. The optimized PCN‐FeS 2 exhibited an H 2 O 2 production rate of 1657 µmol·L − 1 ·h − 1 , representing an 8.3‐fold enhancement over pristine PCN, owing to improved charge separation and efficient conversion of toxic superoxide radical (·O 2 − ) intermediates. This catalytic system was designed for transient intra‐articular lavage under acute inflammatory stress, providing controlled, light‐triggered H 2 O 2 generation to promote a reparative microenvironment while minimizing material retention. Therapeutic efficacy was evaluated in a rat model of lipopolysaccharide‐induced acute TMJ arthritis, in which PCN‐FeS 2 was administered through transient low‐pressure intermittent intra‐articular irrigation. Moreover, the oxidation signal contributed to the differentiation of IL10 + regulatory B cells (Bregs) to facilitate chondrocyte recovery. Overall, this study provides a translationally feasible strategy that integrates catalytic chemistry with endogenous immunocommunication for acute TMJ pathology.