Nanozymes have attracted great interest owing to their marvelous advantages, such as high stability, facile preparation, and high tunability. In particular, iron sulfide-based nanozymes (termed as ISNs), as one of the most researched nanomaterials with versatile enzyme-mimicking properties, have proved their potential in biomedical applications. In this review, we briefly summarize the classification, catalytic mechanisms of ISNs and then principally introduce ISNs’ biomedical applications in biosensors, tumor therapy, antibacterial therapy, and others, demonstrating that ISNs have promising potential for alleviating human health.

Chemodynamic therapy (CDT) based on Fenton‐like reaction possesses great potential for anticancer therapy with high efficiency and specificity. However, CDT still suffers low therapeutic efficiency due to intratumoral insufficient H2O2 or unfavorable tumor microenvironment. To enhance tumor treatment and in particular prevent tumor recurrence, the combined strategies with CDT are essentially needed. Herein, a nanocomposite based on Mn2+ and cytosine‐phosphate‐guanine oligonucleotides (CpG ODNs) (MnCpGPNCs) is constructed to combine CDT with immunostimulating responses by exploiting Mn2+‐induced CDT and Mn2+/CpG ODNs‐coinduced immunotherapy against mouse colon tumor cells. Specifically, MnCpGPNCs efficiently deliver and sensitively release Mn2+ in tumor cells to trigger Fenton‐like reaction, causing cell apoptosis. Importantly, Mn2+ also promotes the stimulator of interferon genes pathway to increase the production of type I interferons, thus increasing cytotoxic T lymphocyte infiltration, dendritic cell maturation, and proinflammatory cytokine secretion. Furthermore, CpG ODNs serve as immune adjuvant enhanced the antigen presentation and immune‐eliciting potency. The combination of Mn2+‐based CDT with augmented immunotherapy efficiently inhibits the primary/distance tumors and prevents tumorigenesis. Overall, this newly developed metal‐CpG system demonstrates a paradigm to expand chemodynamic agents as immunotherapy boosters to complement current treatments for tumor elimination and prevention.