Yupeng Wang†
a,
Xinxin Sun†a,
Shunfeng Wanga,
Zhixiao Zhangc,
Jin Sunab,
Cong Luo
ab,
Zhonggui He*ab and
Shenwu Zhang
*a
aDepartment of Pharmaceutics, Wuya College of Innovation, Shenyang Pharmaceutical University, No. 103 Wenhua Road, Shenyang 110016, PR China. E-mail: hezhonggui@vip.163.com; zhangshenwu@syphu.edu.cn; Fax: +86-024-23986321; Tel: +86-024-23986321
bJoint International Research Laboratory of Intelligent Drug Delivery Systems of Ministry of Education, Shenyang Pharmaceutical University, Shenyang 110016, PR China
cDepartment of Pharmacy, The First Affiliated Hospital of Jinzhou Medical University, Jinzhou 121000, China
First published on 4th August 2025
Nanozymes, an innovative class of biocatalytic nanomaterials, have emerged as promising tools in cancer theranostics. By combining the advantages of nanotechnology and enzymes, nanozymes not only mimic the functions of natural enzymes but also specifically target tumor sites, significantly enhancing the efficiency of biological reactions and overcoming the limitations of natural enzymes. In this review, we first introduce the catalytic activities and physicochemical properties of nanozymes. This dual functionality bridges therapeutic intervention and diagnostic precision. Furthermore, this review discusses the relevant antitumor mechanisms of nanozymes, their key roles in multimodal cancer therapies, and their potential as cancer diagnostic tools. Finally, a comprehensive discussion is provided on the advantages, challenges, design rationales, and future directions of nanozymes in clinical translation.
Wider impactThis review highlights the prominent role of nanozymes, a novel class of nanomaterials with enzyme-like catalytic activity, in advancing cancer theranostics. Unlike natural enzymes, nanozymes combine high stability, tunable physicochemical properties, and tumor-targeting capabilities, enabling precise therapeutic intervention and accurate diagnosis. They offer insights into addressing critical challenges in cancer treatment by leveraging tumor microenvironment features to enhance therapeutic efficacy while minimizing off-target effects. The work systematically explores nanozyme-driven multimodal theranostics, offering innovative strategies for precision oncology. By bridging nanotechnology and biomedicine, this review provides a roadmap for designing next-generation cancer therapies and diagnostics, with notable potential for clinical translation. It appeals to researchers in nanotechnology, oncology, and drug delivery, fostering interdisciplinary advancements in personalized medicine. |
With the rapid advancement of nanotechnology, the integration of nanotechnology and enzymes has created new opportunities for cancer diagnosis and treatment. Owing to their nanoscale size, nanomaterials can passively accumulate in tumor tissues via the enhanced permeability and retention (EPR) effect.8 This passive targeting mechanism offers some tumor selectivity compared to larger molecules. However, passive targeting alone does not equate to “precise” targeting, as non-specific accumulation can still occur in normal tissues with vascular leakage.9 Therefore, true precision targeting requires functionalization with antibodies, peptides, aptamers, or small molecules that specifically recognize tumor-associated antigens or receptors.10
Beyond targeting, some nanomaterials exhibit enzyme-like catalytic activity, significantly improving treatment efficiency. Notably, the term “nanozyme” was first introduced by Manea et al. in 2004 to describe gold nanoparticles (AuNPs) with transphosphorylation activity.11 Later, in 2007, iron oxide nanoparticles (IONPs) were found to exhibit intrinsic peroxidase-like (POD-like) activity, greatly advancing nanozyme research in biomedicine.12 Specifically, nanozymes bridge enzyme simulation and material intelligence, imitate the functions of natural enzymes, and also possess the intrinsic ability to dynamically respond to and interact with the biological microenvironment. They integrate multiple functionalities and adapt their behavior to achieve specific therapeutic or diagnostic objectives. Composed of carbon-based nanomaterials, metal nanoparticles, and metal oxide nanostructures, nanozymes exhibit superior stability, selectivity, and therapeutic safety, overcoming natural enzyme limitations such as high cost and instability, thereby advancing cancer diagnostics and therapies.13
Recently, nanozymes have demonstrated significant potential in cancer diagnosis and treatment, highlighting a promising trajectory in this rapidly evolving field. Thus, it is an opportune time to review the latest advancements (Fig. 1). In this review, we first outline the enzymatic activities of functionalized nanozymes, including POD-like, catalase-like (CAT-like), oxidase-like (OXD-like), and superoxide dismutase-like (SOD-like) nanozymes. Although nanozymes can mimic various enzymes (e.g., hydrolases, nucleases), this review focuses on POD-, CAT-, OXD-, and SOD-like activities due to their direct relevance to tumor microenvironment (TME) modulation and established roles in cancer theranostics. Additionally, their unique physicochemical properties include optical, electromagnetic, and catalytic response characteristics. Next, the review explores nanozyme antitumor mechanisms, detailing how they generate reactive oxygen species (ROS), counteract antioxidants, modulate tumor hypoxia, reverse immunosuppression, disrupt energy metabolism, and ultimately induce tumor suppression and regression. Furthermore, the review elucidates the nanozymes-driven cancer diagnostic paradigm and consolidates a multimodal cancer therapeutic strategy involving nanozymes. It also discusses the rationale and challenges associated with the clinical translation and application of nanozymes. Lastly, we highlight future prospects and unresolved challenges in optimizing nanozymes for clinical use, offering actionable insights for designing more effective therapeutic strategies.
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Fig. 2 Schematic representation of nanozymes integrate enzymatic activity with nanomaterial properties. |
Activities | Subtypes | Characteristics | Nanozymes | Ref. |
---|---|---|---|---|
Peroxidase | Iron-based | High catalytic efficiency/good stability/relatively low cost | Fe3O4 NP | 18 |
FeWOx NSs | 19 | |||
Carbon-based | High specific surface area/good electrical conductivity | CDs@NC | 20 | |
PNCNzyme | 21 | |||
Noble metal-based | Surface high active site | MIrP | 22 | |
PdBi NCs | 23 | |||
Metal–organic framework-based | High density catalytic site/good stability/controllability | NixFe-MOF | 24 | |
Catalase | Metal-based | High catalytic efficiency/good biocompatibility | Cu-TCPP-Mn | 25 |
FePOs | 26 | |||
Metal oxide-based | Excellent catalytic stability/selectivity | TM-EnzNAs | 27 | |
A-Pd@MoO3−xNH | 28 | |||
Oxidase | Gold-based | Simulate conventional oxidase | Au@CeO2 | 29 |
Copper-based | Unique electronic structure/catalytic active site | Cu MOF | 30 | |
Cu3/ND@G | 31 | |||
Molybdenum-based | Simulate intracellular molybdenum dependent oxidase | MoO3–x NUs | 32 | |
Fe–MoOV | 33 | |||
Superoxide dismutase | Carbon-based | High catalytic efficiency/biocompatibility | Fe/N-CDs | 34 |
ChA CQDs | 35 | |||
Cerium-based | High catalytic efficiency | CeVO4 | 36 | |
Ce-UiO-66-NO2 | 37 |
Among them, the Fenton-like reaction mechanism is characterized by the degradation of H2O2 catalyzed by nanozymes to produce hydroxyl radicals (˙OH), which act as oxidants for substrate oxidation.39 Wang et al. designed a H2O2 self-sufficient TCP–PDA–CaO2–CeO2 (TPCC) scaffold by incorporating CaO2 and/or CeO2 nanoparticles (NPs) into chitosan solution.40 The CaO2 NPs loaded on the scaffold can release Ca2+ and sufficient H2O2 in the acidic TME. The generated H2O2 was catalyzed by the POD activity of CeO2 NPs, leading to the further production of ˙OH, while the photothermal effect of PDA coating enhanced the POD catalytic effect. In nude mice bearing HN6 cells, the combination of hyperthermia, along with CeO2 and CaO2 NPs, effectively generated highly toxic ˙OH, resulting in marked tumor suppression. Moreover, POD-like activity based on single-atom nanozymes (SAzymes) can effectively decompose H2O2 into ROS by initiating an intracellular catalytic reaction under weakly acidic conditions. Zeng et al. designed a general and simple strategy to synthesize libraries of SAzymes and dual-atom nanozymes (DAzymes) (M1–NC and M1M2–NC) with similar structures.41 Among them, Fe–N4 exhibited superior POD-like activity, with catalytic efficiency significantly enhanced by the incorporation of heteronuclear metal atoms, especially Co atoms. Given the favorable POD-like catalytic effect and photothermal conversion efficiency, in vitro and in vivo experimental results demonstrated that Fe1Co1–NC DAzymes could effectively inhibit melanoma growth through a synergistic treatment approach involving photothermal-enhanced nanocatalytic therapy.
Additionally, many nanozymes exhibit POD-like activity through electron transport mediators, which do not generate ˙OH nor interact with H2O2 via the Fenton reaction.42 Instead, these nanozymes function as electron transport mediums in catalytic reactions.43 Guo et al. employed palladium doping as a key strategy to regulate electron transfer between platinum and ZIF-8 carriers.44 The results indicated that the electron transfer number of PtxPd1@ZIF-8 nanozyme was correlated with the catalytic activity of POD, following a volcanic curve. Notably, Pt4Pd1@ZIF-8 exhibited the high catalytic activity at a moderate electron transfer number, suggesting that the introduction of Pt into Pd gradually increased Pt’s adsorption affinity for key intermediates, achieving optimal performance at Pt4Pd1@ZIF-8. In a related study, Dong et al. found that Fe2+ in Fe3O4 could transfer electrons to the surface through the Fe2+–O–Fe3+ chain, thereby regenerating surface Fe2+ and enabling a sustained POD-like catalytic reaction.45 This process was usually accompanied by the outward migration of excess oxidized Fe3+ from the lattice. After a long period of catalysis, the Fe3O4 nanozymes would undergo a crystalline phase transition to form γ-Fe2O3, exhibiting POD-like activity that could thereby be eliminated. Based on this mechanism, lithium iron phosphate (LiFePO4) was developed as a model material, showcasing the properties of self-consuming nanozymes with internal atoms involved in electron and ion transfer.
Various metallic and nanomaterials have been designed to simulate CAT-like activity, offering excellent strength, toughness, thermal stability, and adjustable catalytic and biocompatible properties.46 Gao et al. developed a tumor-targeting photocatalytic nanosystem called ICPA by attaching a sulfhydryl-terminated AS1411 aptamer to Pt-modified COF NPs and loading the photosensitizer ICG as a model drug.47 Among them, ICPA exhibits CAT-like activity, which can generate O2 by decomposing overexpressed H2O2, effectively relieving the hypoxic microenvironment of tumor tissues. In addition, its photothermal conversion effect not only facilitated the nanoplatform to kill cancer cells through photoinduced hyperthermia but also accelerated the degradation of H2O2 and the generation of toxic singlet oxygen (1O2) via a photocatalytic cascade. Finally, ICPA demonstrated an enhanced therapeutic efficacy in hypoxic tumors through the generation of O2. Despite significant progress in the development of nanozymes, the low affinity of the majority of nanozymes for H2O2 in the TME impedes the nanocatalytic therapeutic effects of these nanozymes. To address this, Su et al. designed a single-atom Fe dispersed N-doped mesoporous carbon nanosphere (SAFe-NMCNs) nanozyme with enhanced H2O2 affinity.48 In the TME, the single-atom Fe structure of SAFe-NMCNs nanozyme showed significant dual-enzyme-like catalytic activity, mimicking both CAT and POD. This nanozyme generated O2 for ultrasound imaging and produced abundant ˙OH for tumor nanocatalytic therapy. In vivo studies on MCF-7 tumor-bearing mice demonstrated that the SAFe-NMCNs + near-infrared (NIR) group achieved the most significant inhibition of tumor growth.
Metal-based oxides and metal–organic frameworks (MOFs) demonstrate excellent physical and chemical properties, including high specific surface area, electron mobility, thermal stability and mechanical strength, which endow them with enhanced catalytic abilities. Hu et al. developed a subnanostructurally convertible gold@ceria nanozyme (STGC) by assembling ultrafine cerium dioxide nanoparticles (CeO2 NPs) onto plasmonic gold nanorods.50 Under NIR radiation, plasma-excited hot electrons transferred from Au to CeO2, triggering CeO2–CeO2−x conversion and producing active oxygen vacancies (OVs). This internal transformation modulated the POD- and OXD-like catalytic activity of STGC-PEG, markedly elevating ROS levels in a spatiotemporal-controllable manner, thereby improving the antitumor efficiency of photocatalytic nanotherapy.
SOD plays a crucial role in maintaining the balance between oxidation and antioxidation in the body, and its function is intricately connected to the development and progression of numerous diseases. In the context of cancer therapy, ensuring an optimal concentration of H2O2 and reduced glutathione (GSH) within the TME is critical for the success of nanozyme-based treatments. Wang et al. prepared FePOs nanospheres with a small particle size, which is ideal for cellular endocytosis.53 These nanospheres exhibited POD-/SOD-/CAT-like activity and demonstrated promising potential in inhibiting tumor growth. Specifically, the FePOs nanozyme exhibited POD-like activity in the acidic tumor environment, thereby catalyzing H2O2 to produce ˙OH, which effectively led to the death of cancer cells. This activity is particularly notable as it allows for a targeted approach that preserves normal tissues. Simultaneously, the enzyme system produced a combined SOD-CAT effect, maintaining the redox balance of healthy cells, and importantly, it mitigated any potential side effects associated with excess H2O2. These side effects could arise from exogenous injection or from the unintended production of O2˙− through SOD activity in healthy tissues. In vivo studies using a 4T1 tumor-bearing mice model demonstrated notable results, revealing a tumor inhibition rate reaching 84.4% after the intratumoral injection of FePOs and H2O2, with no significant physical toxicity observed. Similarly, building on the innovative approach of manipulating redox reaction kinetics within the TME using nanozymes to improve tumor targeting efficiency and reduce collateral damage to surrounding healthy tissues, Lu et al. developed a multi-enzyme-like active nanozyme (CPTH-AT).54 CPTH-AT is prepared by combining 3-amino-1,2,4-triazole (AT) with copper-doped mesoporous polydopamine (CP), further modified by triphenylphosphine (TPP) and hyaluronic acid (HA). HA modification can achieve CD44 receptor-mediated tumor targeting. This modification leads to a 3.1-fold increase in cellular uptake and more than a 5-fold increase in tumor accumulation, thereby enhancing the nanozyme's antitumor efficacy. The structural similarity of AT to natural SOD enabled it to effectively transform the abundant mitochondrial O2˙− into H2O2. Additionally, AT played an important role in stabilizing H2O2 by preventing its decomposition, thereby promoting accumulation within the mitochondria. Once in this environment, the excessive H2O2 was catalyzed by the POD-like activity of the nanozyme, generating highly toxic ˙OH, which subsequently led to oxidative damage of mitochondrial components, triggering apoptosis in cancer cells. The nanozyme ultimately reduced toxic side effects by targeting the accumulation of H2O2 in mitochondria and binding to other enzyme activities.
The integration of PTI with catalytic therapy has emerged as a powerful strategy for precision oncology. Wei et al. developed Au–Fe3O4 Janus nanoparticles (GION@RGD) for NIR-enhanced ferroptosis-based catalytic therapy in triple-negative breast cancer (TNBC).60 The Au domain enabled strong NIR absorption, achieving a photothermal conversion efficiency of 27.5% and inducing a 34.5 °C temperature rise in vitro at 120 μg mL−1. In vivo, laser irradiation elevated tumor temperatures to 64.5 °C, enhancing Fe2+-mediated Fenton reactions via mitochondrial H2O2 amplification, which synergistically triggered lipid peroxidation and ferroptosis. RGD peptide functionalization improved tumor targeting, validated by MRI-guided T2-weighted imaging. This theranostic platform demonstrated effective tumor suppression with an 83% volume reduction.
Expanding beyond photothermal applications, fluorescence-based nanozymes offer multiplexed biomarker detection with enhanced sensitivity. Fu et al. engineered a ratiometric fluorescence platform using Cu-doped carbon nanozymes (CuAA) and Mg/N co-doped carbon quantum dots (Mg–N-CQDs) for glucose sensing.61 The CuAA catalyzed the H2O2-dependent oxidation of o-phenylenediamine (OPD) to fluorescent 2,3-diaminophenazine (DAP) at 558 nm, while Mg–N-CQDs emitted at 444 nm. The inner-filter effect (IFE) between DAP and Mg–N-CQDs enabled self-calibrated detection, achieving a linear range of 2–400 μM and clinical validation in human serum.
Magnetic nanozymes have shown promising potential in MRI-guided theranostics.62 Li et al. developed Mn3O4-based nanoparticles (MPG NPs) for real-time MRI monitoring of multidrug resistance (MDR) in gastric cancer.63 The redox-responsive release of Mn2+ under acidic pH enhanced T1-weighted MRI contrast, enabling precise detection of tumor hypoxia and redox status. Concurrently, Mn2+ mediated Fenton-like reactions with endogenous H2O2 to generate cytotoxic ˙OH, while photothermal conversion under 808 nm laser irradiation amplified therapeutic efficacy, achieving significant tumor growth inhibition in murine models. In parallel, electroactive nanozymes are advancing biosensing technologies. Zhu et al. designed a photoelectrochemical (PEC) aptasensor using Ag2S/Ag-decorated ZnIn2S4/C3N4 Z-scheme heterostructures and Au/Cu2+–boron nitride (BNNS) nanozymes for telomerase (TE) activity detection.64 The Z-scheme heterostructure enhanced charge separation efficiency, while Au/Cu2+–BNNS catalyzed 4-chloro-1-naphthol (4-CN) oxidation to insoluble 4-chloro-1-naphthol dimer (4-CD), blocking interfacial electron transfer and achieving a detection limit of 19 cells per mL. This platform demonstrated enhanced selectivity for cancer cells over normal cells, highlighting its potential for early cancer diagnosis.
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Fig. 3 Schematic illustration of multiple antitumor mechanisms employed by nanozymes in response to the characteristics of the TME. |
To further enhance the catalytic activity of nanozymes, regulating the size and electronic structure of the active site has emerged as a promising strategy. Ai et al. capitalized on this concept by employing a metal–ligand cross-linking strategy to fabricate ultra-small nanoparticles supported by porous carbon nanorods derived from metal-supramolecular polymers.77 The mechanism behind this nanozyme involves the activation of O2 to generate O2˙−, which subsequently oxidizes ascorbic acid (AA) to produce H2O2. This H2O2 is then transformed into harmful ˙OH via a POD-like pathway, ultimately inducing tumor cell death. In vivo evaluations using a 4T1 tumor-bearing mice model demonstrated that the combination of AA and the nanozyme exerted a substantial inhibitory effect on tumor growth, achieving a notable inhibition rate of 60%. In addition to the aforementioned strategies, enhancing the enzyme-like activity of nanozymes can be achieved by facilitating redox cycles in the presence of X-rays. Zhang et al. introduced a nanocomposite composed of SnS2 NPs and Fe3O4 quantum dots (QDs), proposing the concept of X-ray-facilitated redox cycling of POD-like nanozymes.78 Under X-ray irradiation, SnS2 cofactors acted as electron donors, promoting electron transfer to Fe3O4 and thereby regenerating the Fe2+ sites on its surface. These regenerated Fe2+ sites reacted with overexpressed H2O2, resulting in a continuous production of reactive ROS, which enhanced the efficacy of tumor therapy. When subjected to X-ray treatment, the tumors displayed significant growth arrest, particularly in the group treated with PEG-SF NPs (PEG-SF NPs, where SF denotes SnS2–Fe3O4) combined with X-rays, demonstrating the promising potential of this integrated approach.
However, the application of nanozymes in tumor therapy is significantly hampered by poor water stability and biocompatibility.79 To address these challenges, Yang et al. explored the potential of silk fibroin (SF) as a solution.80 They developed biocompatible AuPt bimetallic nanozymes by employing biocrystals derived from chloroauric and chloroplatinic acids as raw materials. The synthesized AuP@SF (APS) nanozymes demonstrated the capability to sustainably oxidize glucose to produce H2O2 and consume intracellular GSH. Furthermore, the APS nanozymes effectively catalyzed the reaction between adsorbed O2 and endogenous H2O2, yielding O2˙− and ˙OH. Similarly, Zeng et al. designed BON nanospheres, which are biodegradable POD-mimicking enzymes enriched with N–O bonds, to catalyze the production of cytotoxic ˙OH.81 Their antitumor experiments in vivo illustrated that mice receiving injections of BON samples, as well as phosphate-buffered saline (PBS) as controls, exhibited significant tumor growth inhibition, with BON nanozymes achieving an notable 97% reduction in tumor growth.
Despite the advancements made, traditional ROS nanomaterials continue to encounter significant challenges. These include limitations related to external energy sources for tissue penetration and dependence on O2 availability, among others.58 To overcome these challenges, Liu et al. integrated ultra-small graphene quantum dots (GQDs) with POD-like activity and natural GOx into a pH-sensitive zeolitic imidazolate framework-8 (ZIF-8), resulting in the creation of an ultra-small nanozyme generator (ZIF@GOx/GQDs).82 In this innovative approach, GOx catalyzed the oxidation of glucose into H2O2 and gluconic acid within the TME, effectively disrupting the energy supply. As gluconic acid gradually induced the dissociation of ZIF-8, the ultra-small GQDs were released, facilitating substantial tumor penetration. Concurrently, the GQDs nanozyme transformed H2O2 into the toxic radical ˙OH, enabling the direct induction of endogenous ROS without relying on O2 or external energy sources. However, it is important to emphasize that the production of ROS by nanomaterials is inherently non-selective, impacting both normal and cancerous cells.79 This lack of selectivity can compromise the functionality of healthy tissues. In response to this limitation, Xu et al. designed a novel HNPs@PPy nanozyme with spatiotemporally controllable catalytic activity.83 This innovative nanozyme features a heme nanoparticle (HNPs) core and a protective polypyrrole (PPy) coating, created through the self-assembly of heme in aqueous solution and in situ polymerization of pyrrole. The steady-state catalytic kinetics demonstrated that HNPs@PPy exhibited superior catalytic activity, comparable to that of natural horseradish peroxidase (HRP). Additionally, therapeutic evaluations in 4T1 tumor-bearing mice indicated that HNPs@PPy outperformed HNPs in inhibiting tumor growth. Notably, under NIR laser irradiation, HNPs@PPy could facilitate spatiotemporally controllable production of ROS in cancer cells, achieving selectivity in cancer treatment.
To counteract the protective effect of GSH in tumor cells, innovative nanozymes with enzyme-like activity of oxidizing GSH have been developed, thereby enhancing the antitumor efficacy of various ROS-generating therapeutic agents. Zou et al. devised a novel approach by co-encapsulating iridium oxide nanozymes (IrOx) and β-lapachone (Lap) within thermally responsive phase change materials (PCMs) to create phase change cascade nanomedicines known as Lap-IrOx@PCM.89 In this system, the POD-like activity of IrOx enables it to react with endogenous H2O2, resulting in the release of cytotoxic ˙OH. Concurrently, IrOx exhibits glutathione oxidase-like activity to consume GSH and contributing to the accumulation of harmful ROS. Additionally, metal-based nanozymes can deplete GSH using their intrinsic physicochemical properties. Shen et al. designed a magnetic hyperthermia nanozyme, Ir@MnFe2O4 NPs, which targets mitochondria.90 Under the influence of an alternating magnetic field (AMF), these nanoparticles induce localized heating, resulting in mitochondrial damage (known as the magnetic hyperthermia effect). Notably, when GSH is overexpressed in cancer cell mitochondria, it reduces Fe(III) on the nanoparticle surface to Fe(II), leading to GSH depletion. Ultimately, these mechanisms disrupt cellular redox homeostasis, as demonstrated in in vivo experiments with mice harboring transplanted HeLa tumors, where the Ir@MnFe2O4 NPs + AMF treatment group exhibited a statistically significant reduction in tumor volume over a 14-day period.
In addition to the above innovative design using the characteristics of nanozymes themselves, improving the catalytic activity of nanozymes through structural redesign has yielded promising results. Li et al. developed a well-designed sandwich structure using cobalt ferrite layered double hydroxide (Co–Fe LDHs).91 This structure can also serve as a nanocore for loading gold nanoparticles (Au NPs) and maleimide (MA). The Co–Fe LDHs@Au@MA compound not only generates ROS and consumes GSH but also alleviates hypoxia through its Co/Fe dual-catalytic cycle, further contributing to the disruption of the established redox equilibrium within TME. Remarkably, the therapeutic efficacy against CT26 tumor-bearing mice reached 75.34% under 808 nm irradiation, showcasing the potential of Co–Fe LDHs@Au@MA to enhance oxidative stress directly at the tumor site and reshape the local TME. Similarly, the concept of defect engineering was introduced into the structural design of the nanozyme to enrich defects and vacancies and promote a better oxidation cycle. Chen et al. employed a nano-casting method to fabricate metallic n-MoSe2 photothermal nanozymes, characterized by highly ordered nanopores and dispersed selenium vacancies.92 The nanoporous structure significantly enhanced the POD-like activity through the ultra-high 1T MoSe2 phase transition while also increasing the consumption of endogenous antioxidant GSH, thus amplifying oxidative stress within the tumor. Furthermore, the metal MoSe2 with its ordered nanopores could stimulate SPR effects, enhancing photothermal therapeutic properties and oxidative stress within the NIR biological window. Consequently, under NIR laser irradiation, MoSe2 effectively disrupted the balance of redox and metabolic homeostasis in tumor regions, significantly improving therapeutic outcomes and highlighting the multifunctional potential of engineered nanozymes in cancer treatment.
In the hypoxic TME, antitumor T-cell activation and effector functions are suppressed, enabling immune evasion by tumor cells.71 Consequently, it is reasonable to hypothesize that reversing this immunosuppressive state may be achievable through alleviating the hypoxic conditions within tumors. The capacity of nanozymes to enhance O2 transport via enzyme-like activity has been well established. In this context, Wang et al. utilized this capability to develop a nanozyme reactor termed CDSDM nano-reactor (NR), which comprises a CaO2/DOX core and a biocompatible SiO2/DOX–MnO2 shell.98 A key feature of this design is that biocompatible CaO2 serves as an O2 storage component capable of efficiently releasing O2 or H2O2, thereby providing substantial oxygenation throughout tumor tissue and mitigating hypoxia. Subsequent in vivo experiments conducted on B16F10 tumor-bearing mice demonstrated that the antitumor efficacy of cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) blockade was statistically more pronounced when used alongside CDSDM NPs compared to CTLA-4 blockade alone. These experimental findings indicate that the CDSDM NP delivery system effectively alleviates tumor hypoxia and reverses immunosuppressive conditions within the TME, thus markedly synergistically enhancing the efficacy of CTLA-4-based immunotherapy.
In addition, nanozymes can be loaded with immunomodulators to enhance their therapeutic efficacy. For instance, Deng et al. integrated Mn and SiO2 onto CaCO3 nanoparticles through cation exchange and heterophase nucleation, resulting in the development of a calcium–manganese dual-ion hybrid nanomaterial (CMS).99 This innovative material serves as an immune adjuvant that alleviates hypoxia within tumors while simultaneously activating the innate immune response and adaptive immune priming. It induces the activation of the stimulator of interferon genes (STING) signaling pathway via Mn2+, promotes the polarization of tumor-associated macrophages (TAMs) from M2 to M1 phenotype, and effectively activates dendritic cells (DCs) for enhanced antigen presentation. The experimental results demonstrated significant lymphocytic infiltration of tumor-specific cytotoxic T lymphocytes (CTLs) into tumor tissues. In studies using a 4T1 triple-negative breast cancer model, the M1/M2 macrophage ratio in the CMS-treated group was significantly higher than in controls, reaching a notable 4.8-fold increase.
Not only that, the nanozyme, while serving as a carrier, also demonstrated a synergistic effect when combined with immunomodulators, thereby enhancing its antitumor efficacy. For instance, Xu et al. constructed iron manganese silicate nanoparticles (IMSN) coated with PEG and loaded with transforming growth factor-β (TGF-β) inhibitor (TI) to create IMSN-PEG-TI nanocomposites.100 The IMSN exhibits enzyme-like activities, including POD and CAT functions, which enable it to generate ˙OH and O2. In vitro experiments using multicellular tumor spheres (MCTS) and in vivo animal models revealed that the synergistic interaction between IMSN nanomaterials and TI significantly augmented catalytic activity. Notably, both IMSN and TI effectively modulate the TME, alleviate tumor hypoxia, and increase the M1/M2 macrophage ratio and reduce the proportions of CD4+ regulatory T cells (Tregs) and CD8+ T cells. Another strategy involves combining nanozymes with immune cells to jointly target solid tumors. Zhu et al. synthesized a tumor-specific nanozyme HA@Cu2−xS-PEG (PHCN) through template chemical transformation.101 This nanozyme possesses dual properties of photothermal nanocatalysis (PNC), which can effectively reverse the immunosuppressive cancer environment while reshaping TME structure and function by disrupting its compact structure. The nanozyme-mediated photothermal effect degrades the tumor extracellular matrix and enhances blood perfusion, thus facilitating increased infiltration of B7-H3 chimeric antigen receptor T cells (B7-H3 CAR T cells). Concurrently, this nanozyme generates substantial amounts of ROS, which heighten tumor cell susceptibility to CAR T cell attack while diminishing their immune resistance. Taken together, these studies highlight the potential for the use of nanozymes in combination with immunomodulators and immune cells, opening up new avenues for antitumor therapeutic strategies.
Notably, the combination of nanozyme with GOx resulted in a reduction in nutrient metabolism and inhibited nucleic acid repair capabilities. Tumor cells metabolize glucose through glycolysis to produce amino acids and other biological macromolecules, which serve as essential substrates for nucleic acid repair.107 Consequently, diminishing nutrient metabolism can effectively hinder the ability of tumor cells to perform nucleic acid repair.108
Furthermore, there exists a close relationship between glucose metabolism and adenosine triphosphate (ATP) levels in tumor cells.109 Although anaerobic glycolysis yields less ATP, tumor cells enhance glucose uptake and consequently increase ATP production by upregulating glucose transporters.110 The elevation of ATP not only promotes the proliferation, migration, and survival of tumor cells but also plays a crucial role in signal transduction, influencing processes such as the cell cycle and apoptosis.111 Therefore, employing nanozymes to regulate ATP levels may effectively improve therapeutic outcomes. To this end, Chang et al. developed a porous Cu SAzyme loaded with the glycoside LIK066.112 LIK066 effectively obstructs the energy source required for ATP production by inhibiting the activity of sodium-dependent glucose transporter (SGLT), thereby rendering cancer cells incapable of generating sufficient energy to synthesize heat shock proteins (HSPs). Additionally, Cu SAzyme possesses the capability to convert excess H2O2 present in TME into O2 through catalytic action, thus alleviating tumor hypoxia and activating the catalytic activity of OXD. Moreover, Cu SAzyme can catalyze O2 to form O2˙−, which react with H+ under acidic TME conditions to produce 1O2; it can also facilitate the formation of ˙OH via POD activity. Ultimately, researchers successfully eliminated heat shock proteins present in cancer cells by combining SGLT inhibitors with generated ROS. Through this synergistic strategy, Cu SAzyme loaded with LIK066 efficiently removes HSPs while achieving enhanced mild photothermal therapeutic effects.
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Fig. 4 Schematic illustration of nanozyme catalyzed therapy in combination with other therapeutic strategies. |
Nanozymes | Activities | Substrates | Therapies | Ref. |
---|---|---|---|---|
Cu-MOF | CAT | H2O2 | CDT/PTT | 115 |
Au2Pt–PEG–Ce6 | POD/CAT | H2O2 | PTT/PDT/CDT | 116 |
SnFe2O4 | POD/CAT | H2O2 | PTT/PDT/CDT | 117 |
BMIOC | POD/CAT | H2O2 | PTT/PDT | 118 |
GNSs | CAT | H2O2 | PDT/PTT | 119 |
AMPNRs | POD | H2O2 | CDT/PTT | 120 |
PCF-a | POD/GPx | H2O2/GSH | Chemotherapy | 121 |
AgPd@BSA | POD | H2O2 | Chemotherapy/PTT | 122 |
Pt NPs | CAT | H2O2 | Chemotherapy/sonodynamic therapy | 123 |
rMGB | CAT/GOx | H2O2/glucose | Starvation therapy/PDT | 124 |
IrRu–GOx@PEG NPs | POD/CAT/GOx | H2O2/glucose | Starvation therapy/oxidative therapy | 125 |
Ru@CeO2 YSNs | CAT | H2O2 | RT/PTT | 126 |
MSNR@MnO2–Au | CAT | H2O2 | RT/PTT | 127 |
Pt–CuS | CAT | H2O2 | Sonodynamic therapy | 128 |
IMSNs | CAT | H2O2 | Immunotherapy | 129 |
Bac-Au@Pt | POD/OXD | H2O2/O2 | Immunotherapy/CDT | 130 |
PHCNs | POD | H2O2 | Immunotherapy/PTT | 131 |
The role of nanozymes in enhancing the Fenton-like reaction represents a significant advancement in improving the efficacy of CDT. A notable example is provided by Sang et al., who engineered the H2O2 steady-state disruptor PZIF67-AT.139 This was accomplished through the modification of the small molecule inhibitor 3-amino-1,2,4-triazole (3-AT) and PEG on zeolitic imidazole framework-67 (ZIF-67) nanoparticles. The disruptor demonstrated SOD-mimicking activity, facilitating the conversion of O2˙− into H2O2 while concurrently inhibiting CAT activity and depleting GSH. This dual action impaired the conversion of H2O2 to water, leading to an accumulation of H2O2 within cancer cells. Consequently, this elevated concentration of H2O2 was subsequently transformed into more potent ˙OH, inducing oxidative stress within the cells and enhancing CDT efficacy via the Fenton reaction. It is crucial to recognize that the potential of nanozymes extends well beyond a singular application. They can facilitate a series of synergistic functions through the integration of multiple processes. For instance, photodynamic properties combined with cascaded nanocatalytic reactions can enhance the enzymatic cascade reaction cycle, thereby significantly improving overall therapeutic efficacy. Cao et al. developed Fe3O4/Ag/Bi2MoO6 photoactivatable nanozymes (FAB NPs) by integrating Fe3O4 and Ag nanoparticles with Bi2MoO6 (BMO) nanoparticles, resulting in materials characterized by strong NIR-II absorption.140 This design led to markedly improved photocatalytic activity, as well as ferromagnetic and photothermal effects. As a result, the TME facilitates the exertion of various nanozyme activities, including those that mimic POD, CAT, SOD, and glutathione peroxidase (GPx). This enables the initiation of an enzyme-linked reaction that continuously generates both ˙OH and 1O2. Following the administration of FAB NPs combined with laser irradiation in 4T1 tumor-bearing mice, tumor temperatures increased to 45.6 °C within 7 minutes, achieving effective photothermal therapy. Notably, without laser application, CDT utilizing FAB NPs exhibited limited inhibition of tumor growth. However, implementing daily seven-minute laser irradiations resulted in a notable 80% reduction in tumor volume compared to control groups. In fact, twice-daily laser treatments culminated in complete tumor regression within 16 days, underscoring the synergistic efficacy derived from the integrated approaches of CDT, photodynamic therapy (PDT), and PTT using FAB NPs.
Further, the integration of CDT with PTT constitutes a robust strategy to elevate local temperatures through synergistic effects. This approach not only accelerates the Fenton reaction but also enhances the therapeutic efficacy of CDT. Qian et al. demonstrated this synergy through the synthesis of 9 T-PUNNC via a one-pot magnetic solvothermal method using nickel chloride hexahydrate and polyethylene glycol as precursors under a 9 T high magnetic field.141 The resulting nanoparticle design exhibited needle-like nanostructures that improved NIR light absorption in NIR-II, converting it into localized hyperthermia for effective photothermal treatment. Concurrently, the Fenton-like activity of nickel ions (from nickel chloride hexahydrate) facilitated Ni2+ release under NIR light, which mediated CDT. In vivo experiments indicated that treatment with 9 T-PUNNC (9 T-magnetic field-synthesized PEG-stabilized nickel nanocrystals) effectively eliminated tumor cells in mice bearing 4T1 tumors, demonstrating nearly a 12-fold increase in efficacy compared to controls, along with an approximate 9-fold reduction in tumor growth under irradiation at 1064 nm. The advantages extend beyond this; the nanozyme can also function as a carrier for photosensitizers, thereby enhancing synergies with PDT. This combination of the two modalities has the potential to yield synergistically enhanced therapeutic efficacy. Sheng et al. developed a formulation named Ce6@MIL-100/HA (CMH NPs) by encapsulating Ce6 within MIL-100 nanoparticles, which were subsequently coated with HA.142 These CMH NPs exhibited POD-like activity and could interact with the elevated levels of H2O2 present in tumors. The ˙OH and O2 generated by CMH NPs contributed to both CDT and alleviation of hypoxia. Furthermore, upon exposure to NIR light irradiation, the Ce6-mediated photodynamic reactions not only produced cytotoxic 1O2, enhancing O2 supply and improving PDT effectiveness but also generated additional H2O2, thus amplifying the Fenton-like reaction. This cascade effect resulted in a highly efficient therapeutic cycle. Subsequent injection of CMH NPs into mice bearing 4T1 tumors followed by irradiation with a 671 nm NIR laser demonstrated a significant reduction in tumor volume. This suggests that the combined therapeutic modalities of CDT and PDT can lead to nearly complete inhibition of tumor growth.
In addition to traditional approaches, research has shown that nanozymes, which are engineered nanoparticles that mimic enzymatic functions, can significantly improve the effectiveness of RT by creating synergistic relationships between these treatment modalities. A compelling example of this innovation is presented in the work of Huang et al., who developed a biomimetic nanozyme system (CF) that integrates an FeS2 nanozyme with cancer cell-derived exosomes (CDE).148 The CF system showcased remarkable capabilities, as it harnessed the activities of glutathione oxidase activity and POD to deplete GSH levels within tumor tissues. This depletion catalyzed significant production of ˙OH from intracellular H2O2, thereby disrupting redox homeostasis and compromising mitochondrial integrity, which ultimately mitigated RT resistance. Furthermore, following the injection of these engineered nanomaterials into the tail veins of mice bearing 4T1 tumors, radiofrequency (RF) irradiation facilitated circulation to TME, where it was endocytosed by tumor cells, allowing for FeS2 release within the TME. This mechanism highlights the therapeutic potential of the CF + RT system, which profoundly inhibited tumor growth—tumor volume expansion was nearly fully inhibited during treatment.
Building on this paradigm, Yuan et al. synthesized Mn3O4 nanoparticles encapsulated within hollow mesoporous silica nanoparticle (HMSN) channels, subsequently loading them with DOX and functionalizing them with arginine–glycine–aspartic acid (RGD) peptide.149 This innovative construct, designated as DOX@HMSN/Mn3O4(R), established an integrated platform for radiation sensitization, chemotherapy, and catalytic therapy. The dual functionality of DOX@HMSN/Mn3O4(R) enabled it to function both as CAT-like and OXD-like activities, thereby disrupting the redox balance through excessive ROS production and the reduction of Mn3+ to Mn2+. This reaction not only initiated TME responses but also exhibited significant antitumor activity in both in vitro and in vivo settings. Notably, during radiotherapy, high-energy X-rays stimulated the outer electrons of the nanozyme, resulting in the generation of photoelectrons that participated in OXD-like enzymatic reactions. This process amplified ROS accumulation, significantly enhancing the efficacy of both RT and chemotherapy. To comprehensively evaluate the antitumor potential of the DOX@HMSN/Mn3O4(R) nanozyme, a nude mice model bearing A375 xenografts was established. Following intravenous administration of these nanomaterials, mice underwent X-ray irradiation at a dosage of 2 Gy over a month-long treatment period. The combination approach demonstrated significantly antitumor efficacy compared to treatment with the nanozyme alone, further emphasizing the synergistic benefits of integrating novel nanozyme strategies with established therapeutic modalities.
However, since RT is known to pose risks to the nervous system, which is a crucial target of ionizing radiation exposure, it is essential to develop therapeutic strategies that effectively eliminate tumors while also protecting neuronal health.150 In a compelling study conducted by Han et al., which involved CeVO4 nanozymes in a glioblastoma (GBM) radiotherapy model, researchers uncovered a significant dual role: CeVO4 nanozymes not only protected neuronal cells from high-dose ionizing radiation damage but also effectively destroyed tumor cells.151 Further investigation revealed that within the acidic TME, CeVO4 accumulated substantially in endosomes, where it released ROS to mediate tumor cell apoptosis by catalyzing the decomposition of H2O2 and generating ˙OH. Conversely, in the neutral environment of neuronal cells, CeVO4 effectively avoided lysosomal degradation and predominantly accumulated in and around mitochondria. This strategic localization enabled the nanoparticles to prevent radiation-induced damage in neuronal cells through enhanced SOD-like activity.
Within this context, certain nanozymes exhibiting GOx-mimicking activity can be integrated with starvation therapy to enhance overall treatment efficacy. A notable example is the work by Fu et al., who developed a bionic CoO@AuPt nanozyme.157 This nanozyme was synthesized by assembling Au and Pt nanoparticles onto the surface of hollow CoO nanocapsules. The intrinsic CAT and POD activities of these nanoparticles facilitate the decomposition of substantial amounts of H2O2 within cells, resulting in the production of O2 and ˙OH. Furthermore, the Au/Pt nanosatellites demonstrate robust GOx-like activity. In the presence of O2, they significantly reduce glucose levels within tumors while concurrently generating large quantities of H2O2. This interplay between glucose consumption and H2O2 generation effectively promotes tumor starvation and enhances outcomes in CDT through an enzymatic self-supply mechanism for H2O2. In vivo evaluations in BALB/c mice bearing 4T1 tumors revealed a tumor growth inhibition index (TGI) of 58.6% on day 15 for the CoO@AuPt NPs treatment group, significantly exceeding the 29.5% inhibition observed in the DOX-treated group. These compelling findings confirm that CoO@AuPt NPs confer effective tumor inhibition. Building upon this foundation, Zeng et al. further advanced the field by designing a nanophase mixture composed of porous Fe2O3 nanoparticles and ultra-small Au NPs for the synergistic treatment of triple-negative breast cancer (TNBC).158 This Fe2O3/Au nanozyme exhibited prominent GOx-like activity, facilitating the conversion of glucose into gluconic acid and H2O2. This dual action not only depletes energy resources for tumor cells but also generates H2O2, which can be transformed into ˙OH via its significant POD-like activity. Moreover, the modification of Au NPs significantly enhances the photothermal conversion efficiency of the porous Fe2O3 nanoparticles. In vivo studies using a 4T1 tumor-bearing BALB/c mice model demonstrated that the Fe2O3/Au–PEG treatment combined with laser exposure increased the tumor site temperature by 14 °C, reaching as high as 39 °C, and effectively slowed tumor growth. These results suggest that the Fe2O3/Au hybrid nanozyme represents a multifunctional therapeutic agent, acting through multiple mechanisms including starvation therapy, CDT, and PTT.
A particularly promising avenue of research lies in the integration of GT with catalytic therapies that utilize nanozymes. This combination capitalizes on the catalyzed release of loaded drugs alongside specific gas molecules, ultimately resulting in a synergistic antitumor effect through the production of toxic gases and ROS. In a compelling study conducted by Ning et al., iron sulfide doxorubicin nanoparticles (FeS-Dox@bLf NZs) were developed to enhance therapeutic efficacy.163 These nanoparticles, coated with bovine lactoferrin and encapsulating doxorubicin, exploit their POD-like activity under acidic conditions during synthesis. This process leads to the release of Fe2+ and S2−, which subsequently generate ˙OH and H2S, respectively. After intravenous administration and laser irradiation, FeS-Dox@bLf NZs significantly affected body weight and tumor progression in 4T1 tumor-bearing mice. The experimental results confirmed that PDT could effectively induce apoptosis via H2S, thereby enhancing the overall performance of FeS-Dox@bLf NZs. Notably, this innovative formulation mitigated the side effects typically associated with doxorubicin in critical tissues, elevated free radical levels within 4T1 cells, and exhibited enhanced antitumor efficacy. Building on this theme, Chen et al. explored an innovative collaboration that combines a SO2 prodrug, benzothiazole sulfinate (BTS), with copper single-atom nanozymes (Cu SAZ) encapsulated within platelet membrane vesicles (PV).164 The Cu SAZ nanoparticles, characterized by their POD-like activity, demonstrate remarkable NO-generating capabilities. Importantly, as BTS releases SO2, this process generates the free radical SO3˙−, which plays a crucial role in inducing apoptosis in tumor cells. Furthermore, there is a self-amplifying effect, marked by a reduction in GSH levels and an increase in H2O2 concentrations within the TME. The efficacy of BTS was validated through in vivo experiments utilizing a BALB/c nude mice model, achieving a notable tumor growth inhibition rate of over 90% alongside strong tumor targeting and biocompatibility.
Phototherapy encompasses two primary modalities: PDT and PTT.170 PDT is predicated on the administration of safe, non-toxic photosensitizers that, upon exposure to light, generate 1O2—a potent agent capable of inducing cell death in tumors.171 Chen et al. demonstrated the efficacy of hollow mesoporous silica nanoparticles (HMSNs) as carriers for ultra-small Au NPs and MnO2 within a TME-responsive cascade catalytic reactor.172 In this innovative model, MnO2 catalyzes the conversion of O2 into highly toxic 1O2 under 630 nm light irradiation. Simultaneously, Au NPs facilitate the oxidation of glucose, producing H2O2 as a substrate for MnO2; this process amplifies O2 production and addresses significant challenges posed by hypoxic conditions within tumors. In studies involving 4T1 tumor-bearing mice, the HAMF group exhibited a notable cell death rate of 88% under normoxic conditions and even 72% under hypoxic conditions—demonstrating the profound efficacy of PDT enhanced by this novel formulation. Transitioning from PDT to PTT, the latter approach involves the targeted irradiation of photothermal agents with light to induce localized heating, effectively leading to tumor cell destruction.170 Yin et al. have achieved notable progress in this field by developing an smart nanoplatform, Gd2O3@Ir/TMB-RVG29 (G@IT-R), which integrates Ir nanozymes with the well-established photothermal agent TMB.173 The Gd2O3 nanodisks within this formulation not only facilitate heat generation but also inhibit autophagy, thereby enhancing PTT efficacy specifically in gliomas.
Furthermore, the enzyme-like characteristics of nanozymes can be integrated with PDT and PTT to develop a photoresponsive nanocatalytic therapeutic platform that incorporates a photosensitizer, a photothermal agent, and a nanozyme. Yang et al. employed hollow nitrogen-doped carbon nanospheres (HNCSs) loaded with iron phthalocyanine (FePc) to construct a versatile nanoparticle platform (FePc/HNCSs) for synergistic dual phototherapy.174 This innovative combination resulted in enhanced catalytic activity; upon exposure to an 808 nm laser, FePc/HNCSs significantly converted endogenous H2O2 into highly toxic ˙OH, while simultaneously decomposing H2O2 to release O2. The increased O2 availability further augmented PDT efficacy; in experiments with 4T1 breast cancer cells, this platform showed a notable tumor suppression rate of 96.3%, highlighting the potent synergistic therapeutic effects achieved through combined catalytic therapy and dual phototherapy. Continuing the exploration of synergistic strategies, Xu et al. addressed the limitations associated with CuCo2S4 nanoparticles, which have traditionally been regarded as promising agents for PTT.175 They developed ultrasmall CuCo2S4–Pt–PEG nanocomposites that integrate PTT, PDT, and nanozyme catalytic activity. The CuCo2S4–Pt–PEG formulation demonstrated exceptional photothermal performance when exposed to 1064 nm laser treatment at low power density. Concurrently, the catalytic activity of platinum nanozymes significantly enhanced O2 production, thereby amplifying the PDT effect. This multifaceted approach not only effectively targeted cancer cells but also triggered antitumor immune responses to inhibit metastasis, further underscoring the therapeutic potential of integrated PTT/PDT/enzyme-catalyzed strategies.
To enhance the efficacy of chemotherapy, researchers are increasingly investigating the synergistic combination of chemotherapy with nanozyme-catalyzed therapy, leading to more targeted therapeutic strategies. For instance, Li et al. developed innovative nanomedicines termed AgPd@BSA/DOX, which comprise silver–palladium bimetallic nanoparticles serving as drug carriers.179 These nanoparticles were coated with bovine serum albumin (BSA) and loaded with the chemotherapeutic agent DOX. Notably, the AgPd nanoparticles exhibited a superior photothermal conversion efficiency (η = 40.97%) and significantly enhanced POD-like activity compared to their uncoated silver nanoparticle counterparts. This combination enabled AgPd@BSA/DOX to effectively catalyze endogenous H2O2 into ˙OH under NIR laser irradiation, thereby inducing PTT while concurrently releasing DOX. In vivo studies in U14 tumor-bearing mice demonstrated a notable inhibition rate of 98% in the “AgPd@BSA/DOX + laser” group. These findings highlight the remarkable antitumor efficacy of nanomaterials, achieving a sophisticated integration of catalytic therapy, PTT, and chemotherapy. Building upon the principles established by Li et al., Zhang et al. further advanced the field by designing and synthesizing innovative nanomedicines known as PANI/PPy@Au@MnO2 (PPAuMns).180 This agent was developed through the in situ deposition of Au NPs onto the surface of polyaniline (PANI) and PPy nanocomposites, followed by the reduction of KMnO4. In addition to its structural sophistication, PPAuMns was engineered to encapsulate and modify the chemotherapeutic agent DOX in conjunction with folic acid (FA), resulting in the formation of DOX-loaded PPAuMn@FA. The high photothermal conversion efficiency exhibited by both PANI and PPy significantly enhanced the efficacy of PTT. Moreover, the hollow architecture of PPAuMns facilitated targeted pH-responsive drug release, thereby enabling a strategic delivery mechanism. GPx-like and POD-like enzymatic activities played a crucial role in depleting GSH while catalyzing the breakdown of H2O2 into O2, effectively alleviating tumor hypoxia.
Nanozymes integrate catalytic activity with diagnostic characteristics. They amplify signals through enzymatic reactions, such as the oxidation of POD-like substrates, thereby enhancing colorimetric or fluorescent signals.58 In contrast, traditional contrast agents generally rely solely on passive signal enhancement without such amplification mechanisms.184 They can perform multimodal imaging within a single nanozyme entity. For example, it is possible to integrate magnetic MRI, CT, and PAI.185 However, traditional contrast agents are typically restricted to a single imaging modality, necessitating separate administrations for a comprehensive diagnosis.186 In addition, due to surface modification techniques such as PEGylation, nanozymes generally possess better biocompatibility and longer blood circulation times.58 This effectively addresses issues associated with traditional contrast agents, such as the rapid clearance from the body or toxicity problems. For example, some ionic contrast agents used in CT and gadolinium-based MRI contrast agents, which may cause nephrogenic systemic fibrosis, have limitations.187 In comparison, manganese-based or iron oxide-based nanozymes not only provide comparable or even superior contrast enhancement but also exhibit intrinsic catalytic activity.188 This catalytic activity can be exploited for therapeutic applications, thus realizing the integration of diagnosis and treatment. Combining tumor marker detection with nanozyme characteristics offers a promising approach for developing novel early tumor diagnostic strategies. This information is presented objectively and impartially and is intended to serve as a reference for related research and clinical applications.
CtDNA, carrying tumor-specific mutations, serves as a critical biomarker for non-invasive cancer screening. Li et al. engineered a photoelectrochemical (PEC) biosensor using Co3O4 nanozymes to achieve triple-signal quenching mechanism for ctDNA detection.189 By integrating enzyme-free target recycling amplification with the POD-like activity of Co3O4, the system generated insoluble 3-amino-9-ethylcarbazole (AEC) deposits that suppressed MgIn2S4 photoelectric response through competitive light absorption, electron transfer blocking, and hindered ascorbic acid donation. This approach achieved a detection limit of 0.15 fM and a linear range of 0.4 fM–400 pM in human serum, with recoveries of 97–103% (RSD ≤ 3.5%), demonstrating robust clinical applicability for liquid biopsies.
While ctDNA provides genetic insights, CTCs offer direct evidence of metastatic potential. Li et al. addressed CTC detection challenges through a trimetallic AuIrPt nanozyme-based electrochemical cytosensor.190 The AuIrPt nanozymes exhibited multi-enzymatic activities (SOD, POD, CAT) and amplified signals for CTCs captured via a triple-site recognition strategy (anti-mucin 1 (MUC1), anti-epidermal growth factor receptor (EGFR), and epithelial cell adhesion molecule (EpCAM) aptamers). This system achieved a detection limit of 2 cells per mL in whole blood with 90.76–106.4% recovery, minimizing false positives by requiring concurrent antigen expression.
Beyond CTCs, tumor-derived extracellular EVs, including exosomes, carry proteins and nucleic acids critical for cancer subtyping. Gong et al. designed a dual-mode electrochemical/colorimetric sensor using MoS2–Au@Pt nanozymes for exosome analysis.191 The core–shell Au@Pt nanoparticles catalyzed TMB oxidation, generating electrochemical and colorimetric signals, while anti-CD63 aptamers ensured specific exosome capture. The platform achieved detection limits of 9.3 particles per mL (electrochemical) and 4.2 × 103 particles per mL (colorimetric), with 93–106% recovery in clinical serum samples.
Nanozymes | Activities | Imaging modalities | Factors of targeted imaging | Ref. |
---|---|---|---|---|
Pt–CuS Janus | CAT | PA | 808 nm laser irradiation | 195 |
AMP NRs | POD | PA | TME | 196 |
Ag2S@Fe2C-DSPE-PEG-iRGD | POD | MRI/FI | PEG iRGD peptide | 197 |
IL@MIL-101(Fe)@BSA-AuNCs | POD | MRI/FI | BSA-Au NCs and MIL-101(Fe) NPs | 198 |
APMN NPs | POD/CAT | MRI/PA | Au@Pd core | 199 |
FHNPs | POD/CAT | CT | Heat-induced radiolabeling strategy | 200 |
FeWOx NSs | POD | PA/MRI/CT | TMB and 780 nm laser irradiation | 201 |
Given the promising potential of MRI in clinical applications, researchers have proposed that the distinctive physical and chemical properties of nanozymes could further enhance MRI functionality, particularly as prospective contrast agents. A notable investigation in this domain was conducted by Wang et al., who adeptly employed monatomic ruthenium as the active catalytic site anchored within the metal–organic framework Mn3[Co(CN)6]2.204 By encapsulating chlorin e6 (Ce6), they developed a nanoprobe referred to as OxgeMCC-r single-atom enzyme (SAE). The unique coordination of Mn with six nitrogen atoms forms a high-spin Mn–N6 species (S = 5/2), enabling OxgeMCC-r SAE to function effectively as an MRI contrast agent. The efficacy of OxgeMCC-r SAE was validated through studies involving subcutaneous tumor models, where it demonstrated a concentration-dependent signal enhancement effect alongside superior longitudinal relaxation rates. Notably, an increase in imaging intensity was observed with prolonged incubation time of 4T1 cells. This behavior underscored the accumulation of OxgeMCC-r SAE at tumor sites in a time-dependent manner, ultimately suggesting its long-term imaging capabilities and representing a valuable asset for guiding in vivo therapeutic interventions. In addition to these findings, the potential of nanozymes can be further optimized when integrated with MRI probes. A significant contribution to this field was made by Zhu et al., who developed a nanoplatform consisting of Cu/Mn chalcogenide nanoflowers (CMC NFs) in conjunction with 19F-labeled MRI probes.205 Under TME conditions, the paramagnetic Mn from CMC NFs specifically activates the 19F MRI signal by mitigating the paramagnetic relaxation enhancement (PRE) effect experienced by the 19F nuclei. The experimental results demonstrated a marked enhancement of the 19F MRI signal at the tumor site compared to healthy tissue within the same mice, which gradually diminished over time, thereby underscoring the specificity of this response. This study confirmed that CMC NFs activate 19F MRI capabilities, highlighting their excellent potential for tumor-specific imaging. Collectively, these advancements emphasize the transformative role that nanozymes can play in enhancing MRI technology and improving diagnostic outcomes.
In exploring new PA contrast agents, POD-like nanozymes combined with TMB, the most commonly used color developing substrate, can effectively excite photoacoustic signals. This combination not only provides the possibility to enhance the contrast of PA imaging, but also opens new avenues for tumor-specific imaging applications. Ma et al. developed a TMB/MOF/Pt Au-PEG nanoreactor (TMPAs), which is constructed by loading TMB and ultra-small PtAu nanozyme into a MOF of a modified PEG protective layer.207 TMPAs exhibit enzyme-like properties and are able to oxidize colorless TMB to positively charged TMB oxide, thus achieving broadband NIR absorption, enabling tumor-specific PA imaging and photothermal tumor ablation. In addition, the experimental results show that the increase of TMPAs concentration can enhance the photoacoustic signal, and there is a good linear relationship. This finding highlights the potential of TMPAs as a contrast agent for practical applications. Finally, real-time in vivo PA imaging after injection through the tail vein can effectively determine the optimal laser irradiation time, thereby avoiding damage to the surrounding normal tissue. These research findings provide key support for the clinical development of PAI technology and offer new strategies for tumor diagnosis and treatment.
In this context, the development of biocompatible and traceable SAzyme models featuring high catalytic activity alongside imaging capabilities is particularly crucial. Wang et al. successfully dispersed cobalt atoms on nanoporous TiO2 to obtain Co/TiO2 SAzymes exhibiting good intrinsic biocompatibility and stability.211 Utilizing Co/A-TiO2’s hollow nanoporous structures, they further incorporated the 19F MRI contrast agent perfluoro-15-crown-5-ether (PFCE), resulting in PFCE@Co/A-TiO2 nanocomposites. Additionally, they employed Co/A-TiO2 SAzymes labeled with indocyanine green (ICG) to monitor the dynamic biological distribution through fluorescence and dual-mode fluorescence/19F MRI. In vivo experiments revealed that following intravenous injection, both fluorescence and 19F MRI signals within tumor regions gradually intensified. This observation indicates that the hollow nanoporous structure of Co/A-TiO2 SAzymes can effectively load anticancer drugs and contrast agents, facilitating multimodal image-guided synergistic chemotherapy for tumors.
Similarly, mixed bimetallic nanomaterials are preferred over monometallic nanoparticles due to their superior physicochemical properties. Jia et al. developed a dual-modal superbranched AgPd blackbody (AgPd PB) nanozyme.212 Owing to their high atomic number and strong X-ray attenuation capability, the AgPd PB nanozymes significantly enhanced CT signals at tumor sites compared to the control group. Additionally, rhodamine B (RB) was conjugated with the AgPd PB nanozyme for fluorescence tracking purposes. Subsequent studies showed that after intravenous injection of RB-stained AgPd PB nanozymes, their accumulation in mouse tumors increased markedly, consistent with the EPR effect. Concurrently, AgPd PB exhibited high photothermal conversion efficiency. The PA imaging results of tumors were consistent with the fluorescence findings in vivo; collectively, these results underscore the potential of AgPd nanozymes as multifunctional contrast agents. In a similar vein, Wang et al. synthesized Au2Pt–PEG–Ce6 nanozymes by covalently linking the photosensitizer Ce6 with Au2Pt nanozymes.213 The strong absorption characteristics of Au2Pt–PEG–Ce6 in the NIR region facilitated both PA and photothermal (PT) imaging capabilities to guide PTT. Simultaneously, the exceptional X-ray attenuation properties inherent to gold and platinum enabled these Au2Pt–PEG–Ce6 nanozymes to serve as effective contrast agents for X-ray CT imaging. Consequently, Au2Pt–PEG–Ce6 holds promise as a contrast agent for developing tri-modal CT/PA/PT imaging.
In addition, carbon-based nanomaterials have garnered significant attention due to their remarkable stability, low production costs, straightforward synthesis and modification methods, as well as favorable biocompatibility.209 Notably, heteroatom doping can effectively optimize the electronic structure of the active sites, thereby enhancing the catalytic activity of carbon materials and potentially improving imaging capabilities. Zheng et al. developed a hydrated silicate carbon-based nanocapsule (HSC-2) that leverages the highly efficient adsorption properties of nanobeads.214 By adjusting the silicon–carbon ratio within its framework, HSC-2 demonstrated superior performance in NIR-II photoacoustic/fluorescence dual-modal imaging while also achieving effective tumor PTT within the NIR-II window. In a 4T1 tumor model, both PA imaging and fluorescence signals from NSC-2 in the tumor region progressively enhanced, indicating its excellent passive tumor targeting and effective intratumoral accumulation.
CDT efficacy is often limited by fluctuating H2O2 levels and tumor heterogeneity.216 Zhang et al. engineered ROS-responsive Fe3O4-based nanoparticles (FGTL) integrating GOx and immunomodulatory Tuftsin.217 The system disassembles in H2O2-rich TMEs, releasing GOx to amplify Fenton reactions for enhanced ferroptosis, while Tuftsin polarizes immunosuppressive M2 macrophages to antitumor M1 phenotypes and activates cytotoxic T cells. Real-time 129Xe MRI tracked therapeutic efficacy by mapping restored lung ventilation and reduced alveolar septal thickness in murine lung metastasis models. This dual-function platform achieved significant tumor suppression while providing non-invasive assessment of treatment response, highlighting the potential of MRI-guided feedback to optimize CDT-immunotherapy synergy.
CDT leverages ROS dynamics as an intrinsic biological readout, allowing the system to self-regulate catalytic activity in response to changes in oxidative stress levels within the tumor microenvironment.216 In contrast, phototherapy, which depends on external light stimuli, requires precise spatiotemporal control of light delivery to ensure that therapeutic activation aligns with real-time imaging feedback, such as tumor localization or response markers.218 Liu et al. developed core/shell Au@Cu2S nanocrystals encapsulated in denatured bovine serum albumin (dBSA) for optical coherence tomography (OCT)-guided phototherapy.219 The nanocrystals exhibited strong NIR absorption and low cytotoxicity. In vivo OCT imaging revealed time-dependent tumor accumulation, with peak intratumoral signals at 20 minutes post-injection, enabling spatiotemporal control of light delivery. The dBSA coating ensured colloidal stability and enhanced tumor penetration, as confirmed by confocal microscopy. This work underscores the potential of OCT-guided systems to personalize phototherapy dosing, minimizing collateral damage while maximizing tumor ablation.
As nanozymes have advanced from preclinical research to early-stage clinical evaluation, their potential to integrate enzyme mimicry with material-based intelligent properties in cancer theranostics has increasingly attracted attention, though translating these innovations into clinical practice presents unique challenges. First, biocompatibility remains a critical concern. While nanozymes like IONPs have shown promise in preclinical studies, their long-term accumulation in organs such as the liver and spleen can trigger immune responses.229 Additionally, surface modifications such as PEGylation intended to improve circulation can sometimes elicit anti-PEG antibodies, reducing efficacy over repeated administrations.230 This challenge has been observed in trials of PEGylated cerium oxide nanozymes for radioprotection. Second, large-scale manufacturing faces significant challenges. The synthesis of single-atom nanozymes, which exhibit high catalytic specificity, requires precise control over atomic dispersion.231 Similarly, metal–organic framework-based nanozymes, while versatile, face scalability issues due to their sensitivity to reaction conditions.232 This results in high production costs that hinder widespread clinical adoption. Third, regulatory challenges persist, particularly in defining standardized toxicity evaluation metrics for nanozymes, which differ from small-molecule drugs.233
Nonetheless, several challenges must be addressed to realize the full potential of nanozymes in cancer treatment. These include optimizing biocompatibility and stability within complex biological environments, mitigating off-target effects, and ensuring precise control over controlled therapeutic payload release dynamics.79 Additionally, thorough evaluations of safety, efficacy, and long-term effects are crucial for transitioning these therapies from preclinical studies to clinical applications.234 Looking to the future, the potential of nanozymes is poised to expand even further, opening up numerous avenues for advancements in cancer diagnosis and treatment. Future research should prioritize enhancing the catalytic efficiency and specificity of nanozymes, while also developing novel diagnostic techniques that leverage nanozyme technology. Notably, AI-driven knowledge bases enable transparent prediction of nanozymes’ multiple catalytic activities by integrating multi-source data on material properties, catalytic mechanisms, and environmental factors, allowing researchers to identify structure–activity relationships that guide the design of multifunctional nanozymes with tailored POD-, CAT-, or SOD-like activities.235 Additionally, machine learning models have been trained on large datasets to predict catalytic efficiency, substrate specificity, and stability under physiological conditions.236 Moreover, exploring the possibilities of personalized medicine through tailored nanozyme-based treatments could revolutionize patient care. The combination of nanozymes with other nanomaterials or therapeutic agents is expected to yield remarkable therapeutic synergies, thereby significantly improving treatment outcomes. This review not only provides a comprehensive overview of the current state of nanozymes but also emphasizes the critical need to address existing challenges. By doing so, we can fully harness the transformative power of nanozymes in advancing cancer diagnosis and treatment, paving the way for innovative approaches in the future of biomedicine.
Footnote |
† These authors contributed equally to this work. |
This journal is © The Royal Society of Chemistry 2025 |