Extensive efforts are devoted to refining metal sites for optimizing the catalytic performance of single‐atom nanozymes (SANzymes), while the contribution of the defect environment of neighboring metal sites lacks attention. Herein, an iron‐based SANzyme (Fe‐SANzyme) is rationally designed by edge‐site engineering, which intensively exposes edge‐hosted defective Fe–N4 atomic sites anchored in hierarchical mesoporous structures. The Fe‐SANzyme exhibits excellent catalase‐like activity capable of efficiently catalyzing the decomposition of H2O2 into O2 and H2O, with a catalytic kinetic KM value superior to that of natural catalase and reported nanozymes. The mechanistic studies depict that the defects introduce notable charge transfer from the Fe atom to the carbon matrix, making the central Fe more activated to strengthen the interaction with H2O2 and weaken the OO bond. By performing catalase‐like catalysis, the Fe‐SANzyme significantly scavenges reactive oxygen species (ROS) and alleviates oxidative stress, thus eliminating the pathological angiogenesis in animal models of retinal vasculopathies without affecting the repair of normal vessels. This work provides a new way to refine SANzymes by engineering the defect environment and geometric structure around metal sites, and demonstrates the potential therapeutic effects of the nanozyme on retinal vasculopathies.

Sepsis is a systemic inflammatory response syndrome with high morbidity and mortality mediated by infection-caused oxidative stress. Early antioxidant intervention by removing excessively produced reactive oxygen and nitrogen species (RONS) is beneficial to the prevention and treatment of sepsis. However, traditional antioxidants have failed to improve patient outcomes due to insufficient activity and sustainability. Herein, by mimicking the electronic and structural characteristics of natural Cu-only superoxide dismutase (SOD5), a single-atom nanozyme (SAzyme) featuring coordinately unsaturated and atomically dispersed Cu-N 4 site was synthesized for effective sepsis treatment. The de novo-designed Cu-SAzyme exhibits a superior SOD-like activity to efficiently eliminate O 2•− , which is the source of multiple RONS, thus blocking the free radical chain reaction and subsequent inflammatory response in the early stage of sepsis. Moreover, the Cu-SAzyme effectively harnessed systemic inflammation and multi-organ injuries in sepsis animal models. These findings indicate that the developed Cu-SAzyme possesses great potential as therapeutic nanomedicines for the treatment of sepsis.

Copper (Cu) is an essential trace element in the human body that is involved in the formation of several natural enzymes, such as superoxide dismutase and cyclooxygenase. Due to the high density of the outer electron cloud of Cu, which allows the transfer of multiple electrons, Cu is often used as the catalytic center in various metabolic enzymes. However, both deficiency and excessive accumulation of Cu can result in irreversible damage to cells. Therefore, strategies to regulate Cu metabolism, such as Cu exhaustion and Cu supplementation, have emerged as attractive approaches in anticancer therapy, due to the potential damages caused by Cu metabolism disorders. Notably, recent advancements in nanotechnology have enabled the development of nanomaterials that can regulate Cu metabolism, making this therapy applicable in vivo. In this review, we provide a systematic discussion of the physical and chemical properties of Cu and summarize the applications of nanotechnology in Cu metabolism‐based antitumor therapy. Finally, we outline the future directions and challenges of nano‐Cu therapy, emphasizing the scientific problems and technical bottlenecks that need to be addressed for successful clinical translation.