CAT and inflammatory bowel disease: For instance, Fe and N co-doping in hollow carbon spheres endowed them with appreciable POD-, CAT-, and SOD-like activities (Fan et al., 2020) POD-like activity generates •OH radicals under weak acidic conditions and is effectively used for bacteria-infected wound healing, whereas CAT/SOD activity scavenged generated H2O2 and •O2 under near neutral conditions and used for noninfectious inflammatory bowel disease.