Biodegradable Catalase‐Modified Micelles as Ultrasound Contrast Agents for Inflammation Detection

Abstract Overproduction of hydrogen peroxide (H 2 O 2 ) is a characteristic feature for inflammation and cancer. Ultrasonography is a safe and effective clinical diagnosis method to identify inflammation, yet a fully biodegradable ultrasound contrast agent (UCA) system that is able to reflect the pathophysiological level of H 2 O 2 at diseased tissue with high sensitivity is still scarce. Herein, a self‐assembled biodegradable catalase‐modified poly(ethylene glycol) 44 ‐ b ‐poly(lactic acid) 100 (PEG‐ b ‐PLA) micelle (Cat‐PEG‐PLA) is presented as a sensitive ultrasound contrast agent. It is found that the imaging effect of Cat‐PEG‐PLA is remarkable with an obvious enhancement of ultrasound echogenic signal even in an ultralow (0.33 × 10 −3 m ) inflammation‐relevant H 2 O 2 concentration environment, close to or even lower than the reported lowest ultrasound detectable concentration limits. The ultrasonography of collagen‐induced arthritis rat model’s articular cavity by the Cat‐PEG‐PLA micelle platform is demonstrated, showing highly promising results. Therefore, with superior detection sensitivity and contrast, the system detects H 2 O 2 in arthritis rat model with full biodegradability, providing a novel, safe, and translatable platform for arthritis diagnosis.