Visual theranostic oral nanozymes for IBD from principles to preclinical design

Inflammatory bowel disease (IBD), which includes ulcerative colitis (UC) and Crohn's disease (CD), is a chronic, relapsing inflammatory disorder of the intestine driven by disruption of mucosal immune balance. In this context, mucosal inflammation, oxidative stress, and damage to the epithelial barrier reinforce one another and form a self-perpetuating cycle. Oral nanozymes that combine catalytic removal of reactive oxygen species with in vivo imaging readouts provide a potential platform for site-focused intervention and imaging-based evaluation of IBD. This review focuses on how oral nanozymes are designed to couple imaging and therapy and summarizes recent progress in two overarching directions: single-modality imaging-guided strategies and multimodal imaging-guided strategies. Within the single-modality group, current studies are discussed mainly as computed tomography (CT)-guided strategies and optical/photoacoustic (PA)-guided strategies according to their dominant signal-generation mechanisms. Multimodal imaging-guided strategies, by contrast, integrate structural and functional information on a single platform to support more informative preclinical assessment of IBD. This paper also discusses current limitations in oral delivery, characterization of enzyme-like activity, imaging assessment, and long-term biosafety, thereby outlining key design principles for the next generation of oral nanozymes for visual theranostics in IBD.