normal cells and is more sensitive to reactive oxygen species (ROS) elevation has attracted considerable attention. [1] From this perspective, ROS-generating approaches have been widely explored as a weapon to directly or indirectly kill cancer cells; these include photodynamic therapy (PDT), [2] radiodynamic therapy (RT), [3] sonodynamic therapy (SDT), [4] and chemodynamic therapy (CDT). [5] Promoted by recent advancements in nanochemistry and nanocatalysis, a variety of nanosystems with enzyme-like activities, also called "nanozymes," have been successfully fabricated and applied in various biomedical applications. [6] Among these applications, nanozyme-initiated CDT (NCDT) is emerging as a novel cancer treatment strategy with the potential to mitigate undesired side effects. NCDT is a highly tumor-specific modality for cancer therapy triggered by peroxidase (POD)-like nanozyme-mediated chemical reactions, that is, in situ catalysis of endogenous hydrogen peroxide (H 2 O 2 ) into highly toxic hydroxyl radicals ( • OH) to induce cell apoptosis and necrosis. Although many nanomaterials, including ferromagnetic nanoparticles (γ-Fe 2 O 3 or Fe 3 O 4 ), [7] vanadium oxides, [8] copper oxide, [9] and cerium oxide (CeO 2 ), [10] have revealed POD-like activity for cancer diagnosis Clinical applications of nanozyme-initiated chemodynamic therapy (NCDT) have been severely limited by the poor catalytic efficiency of nanozymes, insufficient endogenous hydrogen peroxide (H 2 O 2 ) content, and its off-target consumption. Herein, the authors developed a hollow mesoporous Mn/Zrco-doped CeO 2 tandem nanozyme (PHMZCO-AT) with regulated multi-enzymatic activities, that is, the enhancement of superoxide dismutase (SOD)-like and peroxidase (POD)-like activities and inhibition of catalase (CAT)-like activity. PHMZCO-AT as a H 2 O 2 homeostasis disruptor promotes H 2 O 2 evolution and restrains off-target elimination of H 2 O 2 to achieve intensive NCDT. PHMZCO-AT with SOD-like activity catalyzes endogenous superoxide anion (O 2 •− ) into H 2 O 2 in the tumor region. The suppression of CAT activity and depletion of glutathione by PHMZCO-AT largely weaken the off-target decomposition of H 2 O 2 to H 2 O. Elevated H 2 O 2 is then catalyzed by the downstream POD-like activity of PHMZCO-AT to generate toxic hydroxyl radicals, further inducing tumor apoptosis and death. T 1 -weighted magnetic resonance imaging and X-ray computed tomography imaging are also achieved using PHMZCO-AT due to the existence of paramagnetic Mn 2+ and the high X-ray attenuation ability of elemental Zr, permitting in vivo tracking of the therapeutic process. This work presents a typical paradigm to achieve intensive NCDT efficacy by regulating multi-enzymatic activities of nanozymes to perturb the H 2 O 2 homeostasis.The ORCID identification number(s) for the author(s) of this article can be found under

Photothermal agents with absorption in the second near‐infrared (NIR‐II) biowindow have attracted increasing attention for photothermal therapy (PTT) on account of their deeper tissue penetration capacity. However, most of the current NIR‐II photothermal agents exhibit low photothermal conversion efficiency (PCE) and long‐term biotoxicity. To overcome these shortcomings, herein, nickel and nitrogen co‐doped carbon dots (Ni‐CDs, ≈4.6 nm) are prepared via a facile one‐pot hydrothermal approach for imaging‐guided PTT in the NIR‐II window. The Ni‐CDs exhibit significant absorption in the NIR‐II region with a distinguished PCE as high as 76.1% (1064 nm) and have excellent photostability and biocompatibility. Furthermore, the Ni‐CDs can be employed as photothermal, photoacoustic, and magnetic resonance imaging contrast agents because of their outstanding photothermal effect and instinctive paramagnetic feature. The Ni‐CDs demonstrate significant PTT efficacy of tumor upon 1064 nm irradiation with a low power density (0.5 W cm−2). The Ni‐CDs can be eliminated from the body via a renal filtration pathway, thereby minimizing their long‐term biotoxicity. Therefore, this work provides a simple and feasible approach to develop photothermal agents with remarkable PCE in the NIR‐II region, presenting good biosafety for multimodal imaging‐guided PTT of tumor.

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