CAT and glioblastoma: Ultrasmall carbon dot-loaded iron SAzymes (Fe-CDs) prepared by Muhammad et al. possessed six enzymatic activities, CAT, SOD, OXD, POD, GSH-Px, and thiol peroxidase (TPx), while BBB-permeable and glioma-targeting peptides were introduced on Fe-CDs for selective glioblastoma (GBM) targeting in vivo.