Designing highly performed uricase-like nanozymes through enzymatic-like colorimetric analysis system is of vital significance for the quantitative detection of uric acid (UA). Herein, series of Ce-UiO-66 nanozymes with different surface charges through the ligand engineering strategy were rationally designed and synthesized as efficient uricase mimics with tailorable uricase-like activities to catalytically convert UA into allantoin and H₂O₂. Importantly, by tuning the functional groups (X = H, NO₂, Br, CH₃, OH) of 1,4-benzoic acid ligands, we explored the relationships between the surface charges of Ce-UiO-66-X nanozymes and their uricase-like activity. Among them, Ce-UiO-66-CH₃ with the moderate surface charge exhibited optimal substrate adsorption and product desorption, displaying the highest uricase-like activity. Significantly, H₂O₂, as the product of UA oxidation, enabled Ce-UiO-66-CH₃ itself as a dose-dependent chromogenic substrate of H₂O₂, giving a white-to-orange color evolution due to the Ce-UiO-66-CH₃-to-CeO₂ phase transition. Afterwards, a smartphone-assisted all-in-one enzyme/reagent-free biosensor based on Ce-UiO-66-CH₃ was established for the precise visual detection of UA analysis, which was featured by a wide detection range (31~4000 µM), a high sensitivity (limit of detection: 8.9 µM), a rapid response (~3 min), a high structural stability and a high anti-interference ability.

Sorafenib, as a first-line drug for advanced hepatocellular carcinoma (HCC), could trigger ferroptosis by inhibiting cystine/glutamate transporter. However, low-level intracellular iron and insufficient activation of adenosine monophosphate (AMP)-activated protein kinase (AMPK) confer impaired response to sorafenib. In this study, a unique sorafenib nanocomposite dexterously modified with Fe-Material of Institut Lavoisier (sora@Fe-MIL) was synthesized to escalate intracellular iron level and activate AMPK, further potentiating the ferroptotic effect of sorafenib. Remarkably, this strategic deployment of sora@Fe-MIL triggered an extensive demise of cancer cells, while manifesting negligible deleterious impact on normal cells. Two prominent ferroptosis biomarkers, glutathione peroxidase 4 (GPX4) and solute carrier family 7 member 11 (SLC7A11), underwent pronounced downregulation, underscoring the efficacy of this strategy in inducing ferroptosis. Furthermore, the bioactivity of AMPK was considerably elevated, and its downstream targets were conspicuously inhibited by the treatment with sora@Fe-MIL. Using orthotopic HCC animal models, we observed a substantial suppression of primary in situ tumor growth, and ribonucleic acid (RNA) sequencing elucidated an elevated degree of ferroptosis and AMPK activation with the treatment of sora@Fe-MIL. In conclusion, we proposed that the meticulously designed strategy for secure and efficacious iron release and AMPK activation could significantly potentiate the ferroptotic impact of sorafenib, thus resuscitating its therapeutic response in HCC patients.

Actual chemical states of single-atom metal on reducible supports remain a fiercely debated topic under reactive environments. Herein, we demonstrate that the single-atom Pt on Co₃O₄ surface undergoes an in-situ reconstruction to form isolated Pt-Co bimetallic sites via reducing coordination number of Pt–O in the presence of hydrogen from both simulations and in-situ X-ray photoelectron spectroscopy. The modified chemical states of Pt greatly promoted H₂ activation, thus delivering a significantly high turnover frequency of 7,448 h⁻¹ (19.5 times over Pt nanoparticles on Co₃O₄) for hydrogenation of cinnamaldehyde. The satisfactory selectivity of 95.2% towards cinnamyl alcohol was ascribed to a tilted adsorption configuration of reactant on the catalyst surface via aldehyde group. We anticipate that the recognitions on in-situ reconstruction of single-atom catalysts (SACs) under the reducing conditions benefit the design of highly-performed hydrogenation catalysts.

Numerous therapeutic anti-tumor strategies have been developed in recent decades. However, their therapeutic efficacy is reduced by the intrinsic protective autophagy of tumors. Autophagy plays a key role in tumorigenesis and tumor treatment, in which the overproduction of reactive oxygen species (ROS) is recognized as the direct cause of protective autophagy. Only a few molecules have been employed as autophagy inhibitors in tumor therapy to reduce protective autophagy. Among them, hydroxychloroquine is the most commonly used autophagy inhibitor in clinics, but it is severely limited by its high therapeutic dose, significant toxicity, poor reversal efficacy, and nonspecific action. Herein, we demonstrate a reductive-damage strategy to enable tumor therapy by the inhibition of protective autophagy via the catalytic scavenging of ROS using porous nanorods of ceria (PN-CeO₂) nanozymes as autophagy inhibitor. The antineoplastic effects of PN-CeO₂ were mediated by its high reductive activity for intratumoral ROS degradation, thereby inhibiting protective autophagy and activating apoptosis by suppressing the activities of phosphatidylinositide 3-kinase/protein kinase B and p38 mitogen-activated protein kinase pathways in human cutaneous squamous cell carcinoma. Further investigation highlighted PN-CeO₂ as a safe and efficient anti-tumor autophagy inhibitor. Overall, this study presents a reductive-damage strategy as a promising anti-tumor approach that catalytically inhibits autophagy and activates the intrinsic antioxidant pathways of tumor cells and also shows its potential for the therapy of other autophagy-related diseases.

CeO₂ with the reversible Ce³⁺/Ce⁴⁺ redox pair exhibits multiple enzyme-like catalytic performance, which has been recognized as a promising nanozyme with potentials for disease diagnosis and treatments. Tailorable surface physicochemical properties of various CeO₂ catalysts with controllable sizes, morphologies, and surface states enable a rich surface chemistry for their interactions with various molecules and species, thus delivering a wide variety of catalytic behaviors under different conditions. Despite the significant progress made in developing CeO₂-based nanozymes and their explorations for practical applications, their catalytic activity and specificity are still uncompetitive to their counterparts of natural enzymes under physiological environments. With the attempt to provide the insights on the rational design of highly performed CeO₂ nanozymes, this review focuses on the recent explorations on the catalytic mechanisms of CeO₂ with multiple enzyme-like performance. Given the detailed discussion and proposed perspectives, we hope this review can raise more interest and stimulate more efforts on this multi-disciplinary field.

Ca²⁺ plays critical roles in the development of diseases, whereas existing various Ca regulation methods have been greatly restricted in their clinical applications due to their high toxicity and inefficiency. To solve this issue, with the help of Ca overexpressed tumor drug resistance model, the phytic acid (PA)-modified CeO₂ nano-inhibitors have been rationally designed as an unprecedentedly safe and efficient Ca²⁺ inhibitor to successfully reverse tumor drug resistance through Ca²⁺ negative regulation strategy. Using doxorubicin (Dox) as a model chemotherapeutic drug, the Ca²⁺ nano-inhibitors efficiently deprived intracellular excessive free Ca²⁺, suppressed P-glycoprotein (P-gp) expression and significantly enhanced intracellular drug accumulation in Dox-resistant tumor cells. This Ca²⁺ negative regulation strategy improved the intratumoral Dox concentration by a factor of 12.4 and nearly eradicated tumors without obvious adverse effects. Besides, nanocerias as pH-regulated nanozyme greatly alleviated the adverse effects of chemotherapeutic drug on normal cells/organs and substantially improved survivals of mice. We anticipate that this safe and effective Ca²⁺ negative regulation strategy has potentials to conquer the pitfalls of traditional Ca inhibitors, improve therapeutic efficacy of common chemotherapeutic drugs and serves as a facile and effective treatment platform of other Ca²⁺ associated diseases.