Catalytic Nanoparticles in Biomedical Applications: Exploiting Advanced Nanozymes for Therapeutics and Diagnostics

Hollow heterojunction nanocages of zeolitic imidazolate framework-8@zinc sulfide@copper sulfide for synergistic tumor therapy

The tumor microenvironment (TME) poses significant challenges for achieving efficient cancer remission through monotherapy, making multimodal synergistic therapy a key strategy in tumor treatment. Here, we designed and constructed a hollow core-shell nanocage based on zeolitic imidazolate framework-8 (ZIF-8), zeolitic imidazolate framework-8@zinc sulfide@copper sulfide (ZIF-8@ZnS@CuS, denoted as ZZCS), for the combined application of chemodynamic therapy (CDT), photothermal therapy (PTT) and photocatalytic therapy (PCT). The Cu2+ ions in ZZCS imparted peroxidase (POD)-like and catalase (CAT)-like activities, enabling the generation of toxic hydroxyl radicals (OH) through POD-like catalysis to enhance CDT effect, while also reacting with overexpressed glutathione (GSH) to elevate intracellular reactive oxygen species (ROS) levels. To overcome the inhibitory effects of hypoxia on PCT in the TME, ZZCS catalyzed the production of O2 from endogenous hydrogen peroxide (H2O2) via CAT-like activity, alleviating hypoxia and enhancing the PCT effect. Furthermore, hollow core-shell heterojunction structure of ZZCS exhibited excellent near-infrared absorption and multiple light reflection effects. Under 808 nm laser irradiation, ZZCS showed a high photothermal conversion efficiency (η = 78.1 %) and generated significant amounts of ROS (OH, O2-, 1O2), enabling the synergistic elimination of tumor cells via PTT and PCT. Benefiting from the combined CDT/PTT/PCT effects, ZZCS demonstrated excellent therapeutic efficacy in vivo, nearly eradicating tumors. This study may provide a promising foundation and potential direction for advancing multimodal tumor therapy. Future studies will focus on conducting long-term investigations to systematically evaluate the efficacy of ZZCS core-shell nanocages in achieving durable tumor eradication.

Red-Light Triggered CO/ROS Release from Porphyrin-Flavonol Hybrid@PC7A Micelles for Eradicating Escherichia coli

Photo-triggered carbon monoxide (CO) release, mediated by reactive oxygen species (ROS), shows a significant potential in therapeutic applications. However, the existing photosensitizers predominantly function as type II ROS generators. When ROS are present in excess, they are always wasted due to their short half-lives, which limit their ability to travel significant distances and effectively achieve therapeutic outcomes. In this study, the biological function of a single-component molecule, PdHF, is investigated. This molecule is formed by covalently conjugating 3-hydroxyflavone (3-HF) to a palladium(II) tetraphenyltetrabenzoporphyrin (PdTPTBP) photosensitizer. Subsequently, PdHF is loaded into the 2-hexamethyleneimino ethyl methacrylate (C7A)-modified PEG-b-PCL block copolymer (PC7A) to form a PdHF@PC7A micellar system capable of co-releasing CO and ROS under red-light irradiation. CO/ROS co-release can be attributed to the generation of singlet oxygen species that not only oxidize 3-HF to release CO but are concurrently reduced by the tertiary amine, C7A, to form cytotoxic superoxide anions and hydrogen peroxide. In vitro studies on these positively charged micelles validate a high biosafety and excellent antibacterial effects with competent elimination of Gram-negative bacteria, Escherichia coli. Furthermore, evidence of micelle uptake by bacterial cells supports synergistic photodynamic and gas therapy through intracellular CO/ROS co-release.

Redox disruption using electroactive liposome coated gold nanoparticles for cancer therapy

Cancer remains a global health challenge necessitating innovative therapies. We introduce a strategy to disrupt cancer cell redox balance using gold nanoparticles (Au NPs) as electron sinks combined with electroactive membranes. Utilizing Shewanella oneidensis MR-1 membrane proteins, we develop liposomes enriched with c-type cytochromes. These, coupled with Au NPs, facilitate autonomous electron transfer from cancer cells, disrupting redox processes and inducing cell death. Effective across various cancer types, larger Au NPs show enhanced efficacy, especially under hypoxic conditions. Oxidative stress from Au@MIL (MIL: membrane-integrated liposome) treatments, including mitochondrial and endoplasmic reticulum lipid oxidation and mitochondrial membrane potential changes, triggers apoptosis, bypassing iron-mediated pathways. Surface plasmon band and X-ray absorption near-edge structure (XANES) analyses confirm electron transfer. A SiO2 insulator coating on Au NPs blocks this transfer, suppressing cancer cell damage. This approach highlights the potential of modulated electron transfer pathways in targeted cancer therapy, offering refined and effective treatments.

Advancements in research on the precise eradication of cancer cells through nanophotocatalytic technology

The rapid development of nanotechnology has significantly advanced the application of nanophotocatalysis in the medical field, particularly for cancer therapy. Traditional cancer treatments, such as chemotherapy and radiotherapy, often cause severe side effects, including damage to healthy tissues and the development of drug resistance. In contrast, nanophotocatalytic therapy offers a promising approach by utilizing nanomaterials that generate reactive oxygen species (ROS) under light activation, allowing for precise tumor targeting and minimizing collateral damage to surrounding tissues. This review systematically explores the latest advancements in highly efficient nanophotocatalysts for cancer treatment, focusing on their toxicological profiles, underlying mechanisms for cancer cell eradication, and potential for clinical application. Recent research shows that nanophotocatalysts, such as TiO2, In2O3, and g-C3N4 composites, along with photocatalysts with high conduction band or high valence band positions, generate ROS under light irradiation, which induces oxidative stress and leads to cancer cell apoptosis or necrosis. These ROS cause cellular damage by interacting with key biological molecules such as DNA, proteins, and lipids, triggering a cascade of biochemical reactions that ultimately result in cancer cell death. Furthermore, strategies such as S-scheme heterojunctions and oxygen vacancies (OVs) have been incorporated to enhance charge separation efficiency and light absorption, resulting in increased ROS generation, which improves photocatalytic performance for cancer cell targeting. Notably, these photocatalysts exhibit low toxicity to healthy cells, making them a safe and effective treatment modality. The review also discusses the challenges associated with photocatalytic cancer therapy, including limitations in light penetration and the need for improved biocompatibility. The findings suggest that nanophotocatalytic technology holds significant potential for precision cancer therapy, paving the way for safer and more effective treatment strategies.

A Single H2S-Releasing Nanozyme for Comprehensive Diabetic Wound Healing through Multistep Intervention

Diabetic wound healing presents a significant medical challenge and requires multistep interventions due to comprehensive wound environments, such as hyperglycemia, bacterial infection, and impaired angiogenesis. However, current multistep interventions are complicated and need on-demand sequential release and synergy of multicomponents. Herein, a H2S-releasing cascade nanozyme (FeS@Au), which is composed of ultrasmall gold nanocluster (AuNC) loaded on ferrous sulfide nanoparticle (FeSNP), is developed as a single component to regulate glucose level, eliminate infection, and promote angiogenesis, achieving multistep interventions for comprehensive diabetic wound treatment. The glucose oxidase-like activity of AuNC catalyzes glucose into gluconic acid and H2O2, which not only lowers the local glucose level but also decreases the local pH and increases H2O2 level to boost the peroxidase-like activity of FeSNP to generate abundant hydroxyl radical (reactive oxygen species, ROS), inducing ferroptosis-like death in drug-resistant bacteria. Additionally, FeSNP release H2S in the acidified environment to upregulate hypoxia-inducible factor-1 to enhance vascularization through upregulating the expression of vascular endothelial growth factor (VEGF) and other angiogenesis-related genes, reducing the damage to endothelial cells caused by excessive ROS produced by the nanozyme. In a full-thickness MRSA-infected diabetic rat model, FeS@Au significantly eliminates bacteria, enhances angiogenesis, promotes collagen deposition, and accelerates wound healing. This work presents a single nanozyme with H2S-release for multistep interventions, providing a versatile strategy for healing extensive tissue damage caused by diabetes.

A multifunctional Pt/DMSN nanozyme-based colorimetric-fluorescence sensing platform for breast cancer detection

Nanozyme-linked immunosorbent assay has emerged as a promising strategy for sensitive biosensing. However, the catalytic activity and stability of nanozymes affect the accuracy of immunosorbent assays. In this study, we synthesized a Pt/DMSN nanozyme with peroxidase-mimicking activity, which effectively catalyzed the oxidation of peroxidase substrate 3,3',5,5'-tetramethylbenzidin (TMB) in the presence of hydrogen peroxide. Capitalizing on its peroxidase-like activity, the Pt/DMSN nanozyme was functionalized with dual-fluorescent recognition elements (HER2-mAbs and sk6Ea aptamers) to establish a nanozyme-linked immunosorbent assay platform, which exhibited catalytic stability and substrate affinity comparable to horseradish peroxidase. The resulting Multi-Pt/DMSN platform was used to selectively distinguish HER2-positive breast cancer cells from luminal A, triple-negative breast cancer subtypes, and non-neoplastic cells, achieving a detection limit of 50 HER2-positive cells within 30 min. The combination of robust enzyme-like activity and tumor-targeting properties enables fluorescence imaging, providing dual-mode diagnostic functionality. This work presents a prospective platform for differentiating breast cancer subtypes in early diagnosis.

New horizons for the therapeutic application of nanozymes in cancer treatment

The advent of nanozymes has revolutionized approaches to cancer diagnosis and therapy, introducing innovative strategies that address the limitations of conventional treatments. Nanozyme nanostructures with enzyme-mimicking catalytic abilities exhibit exceptional stability, biocompatibility, and customizable functions, positioning them as promising tools for cancer theranostics. By emulating natural enzyme reactions, nanozymes can selectively target and eradicate cancer cells, minimizing harm to adjacent healthy tissues. Nanozymes can also be functionalized with specific targeting ligands, allowing for the precise delivery and regulated release of therapeutic agents, improving treatment effectiveness and reducing adverse effects. However, issues such as biocompatibility, selectivity, and regulatory compliance remain critical challenges for the clinical application of nanozymes. This review provides an overview of nanozymes, highlighting their unique properties, various classifications, catalytic activities, and diverse applications in cancer treatments. The strategic oncological deployment of nanozymes could profoundly impact future advancements in personalized medicine, highlighting recent progress and prospective directions in enzyme-mimetic approaches for cancer treatment. This review summarizes an overview of nanozymes, highlighting their unique properties, various classifications, catalytic activities, and diverse applications in cancer treatments.

A Dual-Targeting Biomimetic Nanoplatform Integrates SDT/CDT/Gas Therapy to Boost Synergistic Ferroptosis for Orthotopic Hepatocellular Carcinoma Therapy

The development of efficient therapeutic strategies to promote ferroptotic cell death offers significant potential for hepatocellular carcinoma (HCC) treatment. Herein, this study presents an HCC-targeted nanoplatform that integrates bimetallic FeMoO4 nanoparticles with CO-releasing molecules, and further camouflaged with SP94 peptide-modified macrophage membrane for enhanced ferroptosis-driven multi-modal therapy of HCC. Leveraging the multi-enzyme activities of the multivalent metallic elements, the nanoplatform not only decomposes H2O2 to generate oxygen and alleviate tumor hypoxia but also depletes glutathione to inactivate glutathione peroxides 4, which amplify sonodynamic therapy and ferroptotic tumor death under ultrasound (US) irradiation. Meanwhile, the nanoplatform catalyzes the Fenton reaction to produce hydroxyl radicals for chemodynamic therapy. Elevated intracellular reactive oxygen species trigger the cascade release of CO, leading to lethal lipid peroxidation and further enhancing ferroptosis-mediated tumor therapy. This nanoplatform demonstrates robust anti-tumor efficacy under US irradiation with favorable biosafety in both subcutaneous and orthotopic HCC models, representing a promising therapeutic approach for HCC. Additionally, the findings offer new insights into tumor microenvironment modulation to optimize US-triggered multi-modal cancer therapy.

Harnessing Dual Phototherapy and Immune Activation for Cancer Treatment: The Development and Application of BODIPY@F127 Nanoparticles

Conventional phototherapeutic agents are typically used in either photodynamic therapy (PDT) or photothermal therapy (PTT). However, efficacy is often hindered by hypoxia and elevated levels of heat shock proteins in the tumor microenvironment (TME). To address these limitations, a formylated, near-infrared (NIR)-absorbing and heavy-atom-free Aza-BODIPY dye is presented that exhibits both type-I and type-II PDT actions with a high yield of reactive oxygen species (ROS) and manifests efficient photothermal conversion by precise adjustments to the conjugate structure and electron distribution, leading to a large amount of ROS production even under severe hypoxia. To improve biosafety and water solubility, the dye with an amphiphilic triblock copolymer (Pluronic F-127), yielding BDP-6@F127 nanoparticles (NPs) is coated. Furthermore, inspired by the fact that phototherapy triggers the release of tumor-associated antigens, a strategy that leverages potential immune activation by combining PDT/PTT with immune checkpoint blockade (ICB) therapy to amplify the systemic immune response and achieve the much-desired abscopal effect is developed. In conclusion, this study presents a promising molecular design strategy that integrates multimodal therapeutics for a precise and effective approach to cancer therapy.

Atomically Engineered Chlorine Coordination of Iron in Active Centers for Selectively Catalytic H2O2 Decomposition Toward Efficient Antitumor-Specific Therapy

The intervention of endogenous H2O2 via nanozymes provides a potential antitumor-specific therapy; however, the role of the nanozyme structure in relation to the selective decomposition of H2O2 to hydroxyl radicals (•OH) is yet to be fully understood, which limits the development of this therapeutic approaches. Herein, an iron single-atom nanozyme (Fe─N2Cl2─C SAzyme) is reported, which is prepared through precise Fe─Cl coordination based on the construction of a characteristic Fe-containing molecule. Fe─N2Cl2─C exhibits efficient catalytic H2O2 decomposition (2.19 × 106 mm-1 s-1), which is the highest among reported SAzymes. More importantly, it is found that H2O2 selectively decomposed into •OH on the Fe─N2Cl2─C surface, which is attributable to the d orbitals of the Fe active center matching the O-2p electrons of the adsorbed hydroxide (*OH) intermediate. Fe─N2Cl2─C is strongly cytotoxic toward a variety of cancer-cell lines in vitro but not to normal cells. Furthermore, Fe─N2Cl2─C shows an outstanding specific therapeutic effect in vivo; it efficiently destroys solid malignant tumors without injuring normal tissue. Altogether, these findings highlight the selective catalytic decomposition of H2O2 to •OH, which is achieved by engineering the active center on the atomic level, thereby providing an avenue for the development of specific nanomedicines with efficient antitumor activities.

Multi-omics analysis of Au@Pt nanozyme for the modulation of glucose and lipid metabolism

Au@Pt nanozyme, a bimetallic core-shell structure Au and Pt nanoparticle, has attracted significant attention due to its excellent catalytic activity and stability. Here, we propose that Au@Pt improves glucose tolerance and reduces TG after four weeks administration. The transcriptomic analysis of mouse liver tissues treated with Au@Pt nanozyme showed changes in genes related to glucose and lipid metabolism signaling pathways, including glycolysis/gluconeogenesis, pyruvate metabolism, PPAR signaling, and insulin signaling. Moreover, analysis of fecal samples from mice treated with Au@Pt nanozyme showed significant changes in the abundance of beneficial gut microbiota such as Dubosiella, Parvibacter, Enterorhabdus, Monoglobus, Lachnospiraceae_UCG-008, Lachnospiraceae_UCG-006, Lachnospiraceae_UCG-001, and Christensenellaceae_R-7_group. Combined multi-omics correlation analyses revealed that the modulation of glucose and lipid metabolism by Au@Pt was strongly correlated with changes in hepatic gene expression profiles as well as changes in gut microbial profiles. Overall, our integrated multi-omics analysis demonstrated that Au@Pt nanozyme could modulate glucose and lipid metabolism by regulating the expression of key genes in the liver and altering the composition of gut microbiota, providing new insights into the potential applications of Au@Pt nanozyme in the treatment of metabolic disorder.