Ultrasound-triggered piezocatalytic MOF(Hf)-Pt nanozymes for efficient ROS scavenging in the treatment of osteoarthritis

Platinum (Pt)-based nanozymes that effectively exert antioxidant effects exhibit great potential in the treatment of osteoarthritis (OA). However, these nanozymes are easy to agglomerate and have low catalytic efficiency, which can hardly meet the criterion of clinical therapy. To achieve efficient ROS removal, this study develops a novel ultrasound (US)-responsive piezoelectric nanozyme (MOF(Hf)-Pt) based on Pt with multi-enzyme mimicking activities and metal-organic frameworks (MOFs) with excellent piezoelectric properties. Results show that MOF(Hf)-Pt has excellent piezocatalytic enzyme activity, which can be adjusted by varying the intensity and time of US. Mechanistically, MOF(Hf)-Pt can increase ATP output and restore mitochondrial function, thereby reducing inflammatory factor levels. In vivo studies also reveal that under suitable US action, MOF(Hf)-Pt nanozymes can effectively inhibit the deterioration of OA, with reductions in OARSCI scores of 76.90 % and 82.66 % after 4 and 8 weeks, respectively. Particularly, the piezoelectric catalytic effect generated by MOF(Hf)-Pt can reverse oxidative stress-induced articular cartilage damage and promote cartilage regeneration, making it a promising candidate for OA treatment.