Cancer Treatment through Nanoparticle-Facilitated Fenton Reaction

Hollow Porous Carbon Coated FeS2-Based Nanocatalysts for Multimodal Imaging-Guided Photothermal, Starvation, and Triple-Enhanced Chemodynamic Therapy of Cancer

Specific chemical reactions only happen in the tumor region and produce abundant special chemicals to in situ trigger a train of biological and pathological effects that may enable tumor-specific curative effects to treat cancer without causing serious side effects on normal cells or organs. Chemodynamic therapy (CDT) is a rising tactic for cancer therapy, which induces cancer cell death via a localized Fenton reaction. However, the tumor therapeutic effect is limited by the efficiency of the chemical reaction and relies heavily on the catalyst. Here, we constructed hollow porous carbon coated FeS₂ (HPFeS₂@C)-based nanocatalysts for triple-enhanced CDT. Tannic acid was encapsulated in HPFeS₂@C for reducing Fe³⁺ to Fe²⁺, which had a better catalytic activity to accelerate the Fenton reaction. Afterward, glucose oxidase (GOx) in nanocatalysts could consume glucose in the tumor microenvironment and in situ synchronously produce H₂O₂, which could improve Fenton reaction efficiency. Meanwhile, the consumption of glucose could lead to the starvation effect for cancer starvation therapy. The photothermal effects of HPFeS₂@C could generate heat, which further sped up the Fenton process and implemented synergetic photothermal therapy/starvation therapy/CDT. The biodistribution of nanoparticles was investigated by multimodal magnetic resonance, ultrasound, and photoacoustic imaging. These nanocatalysts could trigger the catalytic Fenton reaction at a high degree, which might provide a good paradigm for nanocatalytic tumor therapy.

NIR/Thermoresponsive Injectable Self-Healing Hydrogels Containing Polydopamine Nanoparticles for Efficient Synergistic Cancer Thermochemotherapy

Injectable and self-healing hydrogels with thermoresponsiveness as smart hydrogels displayed injectability, automatic healing, and phase and volume changes as well. Here, the thermoresponsive self-healing hydrogel was prepared via the formation of dynamic covalent enamine bonds between the amino groups in polyetherimide (PEI) and the acetoacetate groups in the four-armed star-shaped poly(2-(dimethylamino)ethyl methacrylate-co-2-hydroxyethyl methacrylate) modified with tert-butyl acetoacetate (t-BAA), SP(DMAEMA-co-HEMA-AA). After adding polydopamine nanoparticles (PDA NPs), the SP(DMAEMA-co-HEMA-AA)/PEI/PDA-NP nanocomposite hydrogel presented phase change and volume shrinkage under near-infrared (NIR) irradiation. The thermoresponsive nanocomposite hydrogel loaded with the anticancer drug doxorubicin (DOX) could be injected into the 4T1 tumor by intratumoral injection. After NIR laser irradiation, the temperature of the hydrogel increased because of the photothermal effect of PDA NPs inducing local hyperthermia. Because the hydrophilicity-hydrophobicity transition of the hydrogel occurred, DOX molecules were squeezed out from the hydrogel at temperatures higher than its lower critical solution temperature (LCST) and the tumor cells suffered from internal stress from the shrunk hydrogel. The injectable nanocomposite hydrogel not only demonstrated the synergism of highly efficient thermochemotherapy but also showed the function of improving drug utilization and precise treatment to reduce the side effects of drugs.

Subcellular Performance of Nanoparticles in Cancer Therapy

With the advent of nanotechnology, various modes of traditional treatment strategies have been transformed extensively owing to the advantageous morphological, physiochemical, and functional attributes of nano-sized materials, which are of particular interest in diverse biomedical applications, such as diagnostics, sensing, imaging, and drug delivery. Despite their success in delivering therapeutic agents, several traditional nanocarriers often end up with deprived selectivity and undesired therapeutic outcome, which significantly limit their clinical applicability. Further advancements in terms of improved selectivity to exhibit desired therapeutic outcome toward ablating cancer cells have been predominantly made focusing on the precise entry of nanoparticles into tumor cells via targeting ligands, and subsequent delivery of therapeutic cargo in response to specific biological or external stimuli. However, there is enough room intracellularly, where diverse small-sized nanomaterials can accumulate and significantly exert potentially specific mechanisms of antitumor effects toward activation of precise cancer cell death pathways that can be explored. In this review, we aim to summarize the intracellular pathways of nanoparticles, highlighting the principles and state of their destructive effects in the subcellular structures as well as the current limitations of conventional therapeutic approaches. Next, we give an overview of subcellular performances and the fate of internalized nanoparticles under various organelle circumstances, particularly endosome or lysosome, mitochondria, nucleus, endoplasmic reticulum, and Golgi apparatus, by comprehensively emphasizing the unique mechanisms with a series of interesting reports. Moreover, intracellular transformation of the internalized nanoparticles, prominent outcome and potential affluence of these interdependent subcellular components in cancer therapy are emphasized. Finally, we conclude with perspectives with a focus on the contemporary challenges in their clinical applicability.

Single-Atom Catalysts in Catalytic Biomedicine

The intrinsic deficiencies of nanoparticle-initiated catalysis for biomedical applications promote the fast development of alternative versatile theranostic modalities. The catalytic performance and selectivity are the critical issues that are challenging to be augmented and optimized in biological conditions. Single-atom catalysts (SACs) featuring atomically dispersed single metal atoms have emerged as one of the most explored catalysts in biomedicine recently due to their preeminent catalytic activity and superior selectivity distinct from their nanosized counterparts. Herein, an overview of the pivotal significance of SACs and some underlying critical issues that need to be addressed is provided, with a specific focus on their versatile biomedical applications. Their fabrication strategies, surface engineering, and structural characterizations are discussed briefly. In particular, the catalytic performance of SACs in triggering some representative catalytic reactions for providing the fundamentals of biomedical use is discussed. A sequence of representative paradigms is summarized on the successful construction of SACs for varied biomedical applications (e.g., cancer treatment, wound disinfection, biosensing, and oxidative-stress cytoprotection) with an emphasis on uncovering the intrinsic catalytic mechanisms and understanding the underlying structure-performance relationships. Finally, opportunities and challenges faced in the future development of SACs-triggered catalysis for biomedical use are discussed and outlooked.

A Metal-Polyphenol-Coordinated Nanomedicine for Synergistic Cascade Cancer Chemotherapy and Chemodynamic Therapy

The clinical application of chemotherapy is impeded by the unsatisfactory efficacy and severe side effects. Chemodynamic therapy (CDT) has emerged as an efficient strategy for cancer treatment utilizing Fenton chemistry to destroy cancer cells by converting endogenous H₂ O₂ into highly toxic reactive oxygen species. Apart from the chemotherapeutic effect, cisplatin is able to act as an artificial enzyme to produce H₂ O₂ for CDT through cascade reactions, thus remarkably improving the anti-tumor outcomes. Herein, an organic theranostic nanomedicine (PTCG NPs) is constructed with high loading capability using epigallocatechin-3-gallate (EGCG), phenolic platinum(IV) prodrug (Pt-OH), and polyphenol modified block copolymer (PEG-b-PPOH) as the building blocks. The high stability of PTCG NPs during circulation stems from their strong metal-polyphenol coordination interactions, and efficient drug release is realized after cellular internalization. The activated cisplatin elevates the intracellular H₂ O₂ level through cascade reactions. This is further utilized to produce highly toxic reactive oxygen species catalyzed by an iron-based Fenton reaction. In vitro and in vivo investigations demonstrate that the combination of chemotherapy and chemodynamic therapy achieves excellent anticancer efficacy. Meanwhile, systemic toxicity faced by platinum-based drugs is avoided through this nanoformulation. This work provides a promising strategy to develop advanced nanomedicine for cascade cancer therapy.

In Situ Polymerized Hollow Mesoporous Organosilica Biocatalysis Nanoreactor for Enhancing ROS-Mediated Anticancer Therapy

The combination of reactive oxygen species (ROS)-involved photodynamic therapy (PDT) and chemodynamic therapy (CDT) holds great promise for enhancing ROS-mediated cancer treatment. Herein, we reported an in situ polymerized hollow mesoporous organosilica nanoparticle (HMON) biocatalysis nanoreactor to integrate the synergistic effect of PDT/CDT for enhancing ROS-mediated pancreatic ductal adenocarcinoma treatment. HPPH photosensitizer was hybridized within the framework of HMON via an "in situ framework growth" approach. Then, the hollow cavity of HMONs was exploited as a nanoreactor for "in situ polymerization" to synthesize the polymer containing thiol groups, thereby enabling the immobilization of ultrasmall gold nanoparticles, which behave like glucose oxidase-like nanozyme, converting glucose into H2O2 to provide self-supplied H2O2 for CDT. Meanwhile, Cu2+-tannic acid complexes were further deposited on the surface of HMONs (HMON-Au@Cu-TA) to initiate Fenton-like reaction to covert the self-supplied H2O2 into •OH, a highly toxic ROS. Finally, collagenase (Col), which can degrade the collagen I fiber in the extracellular matrix (ECM), was loaded into HMON-Au@Cu-TA to enhance the penetration of HMONs and O2 infiltration for enhanced PDT. This study provides a good paradigm for enhancing ROS-mediated anti-tumor efficacy. Meanwhile, this research offers a new method to broaden the application of silica based nanotheranostics.

A H2O2 self-sufficient nanoplatform with domino effects for thermal-responsive enhanced chemodynamic therapy

Chemodynamic therapy (CDT), employing Fenton or Fenton-like catalysts to convert hydrogen peroxide (H2O2) into toxic hydroxyl radicals (˙OH) to kill cancer cells, holds high promise in tumor therapy due to its high selectivity. However, the anticancer efficacy is unsatisfactory owing to the limited concentration of endogenous H2O2. Herein, thermal responsive nanoparticles with H2O2 self-sufficiency are fabricated by utilizing organic phase change materials (PCMs) to encapsulate iron-gallic acid nanoparticles (Fe-GA) and ultra-small CaO2. PCMs, acting as the gatekeeper, could be melted down by the hyperthermia effect of Fe-GA under laser irradiation with a burst release of Fe-GA and CaO2. The acidic tumor microenvironment would further trigger CaO2 to generate a large amount of H2O2 and Ca2+. The self-supplied H2O2 would be converted into ˙OH by participating in the Fenton reaction with Fe-GA. Meanwhile, in situ generation of Ca2+ could cause mitochondrial damage and lead to apoptosis of tumor cells. With efficient tumor accumulation illustrated in in vivo photoacoustic imaging, Fe-GA/CaO2@PCM demonstrated a superior in vivo tumor-suppressive effect without inducing systemic toxicity. The study presents a unique domino effect approach of PCM based nanoparticles with thermal responsiveness, H2O2 self-supply, and greatly enhanced CDT effects, showing bright prospects for highly efficient tumor treatment.

Reactive Oxygen Correlated Chemiluminescent Imaging of a Semiconducting Polymer Nanoplatform for Monitoring Chemodynamic Therapy

In chemodynamic therapy (CDT), real-time monitoring of reactive oxygen species (ROS) production is critical to reducing the nonspecific damage during CDT and feasibly evaluating the therapeutic response. However, CDT agents that can emit ROS-related signals are rare. Herein, we synthesize a semiconducting polymer nanoplatform (SPN) that can not only produce highly toxic ROS to kill cancer cells but also emit ROS-correlated chemiluminescent signals. Notably, the efficacy of both chemiluminescence and CDT can be significantly enhanced by hemin doping (∼10-fold enhancement for luminescent intensity). Such ROS-dependent chemiluminescence of SPN allows ROS generation within a tumor to be optically monitored during the CDT process. Importantly, SPN establishes an excellent correlation of chemiluminescence intensities with cancer inhibition rates in vitro and in vivo. Thus, our nanoplatform represents the first intelligent strategy that enables chemiluminescence-imaging-monitored CDT, which holds potential in assessing therapeutic responsivity and predicting treatment outcomes in early stages.

Engineering H2O2 Self-Supplying Nanotheranostic Platform for Targeted and Imaging-Guided Chemodynamic Therapy

Developing highly efficient chemodynamic therapy (CDT)-based theranostic technology for cancer treatment is highly desired but still challenging. A novel nanotheranostic platform is constructed for enhanced CDT by engineering hybrid CaO₂ and Fe₃O₄ nanoparticles with a hyaluronate acid (HA) stabilizer and NIR fluorophore label. This design not only enables the nanotheranostic agent to afford highly efficient CDT against tumor cells but also confers NIR fluorescence (NIRF) and magnetic resonance (MR) bimodal imaging for in vivo visualization of CDT. Moreover, the use of the HA stabilizer allows for the facile synthesis of the nanotheranostic agent with excellent biocompatibility and active targetability. The nanotheranaostic agent possesses a high capacity of self-supplying H₂O₂ and producing ^•OH in acidic conditions, while retaining the desired stability under physiological conditions. It also demonstrates high selectivity to tumor cells via CDT with minimized toxicity to normal cells. In vivo studies reveal that our nanotheranaostic agent exhibits efficacious tumor growth inhibition via a CDT mechanism with favorable biosafety. Moreover, in vivo visualization of the CDT progress via NIRF and MR bimodal imaging demonstrates specific targeting and treatment of tumors. The developed H₂O₂ self-supplying, active targeting, and bimodal imaging nanotheranostic platform holds the potential as a highly efficient strategy for CDT of cancer.

Encapsulation of glucose oxidase in Fe(III)/tannic acid nanocomposites for effective tumor ablation via Fenton reaction

Increasing the content of reactive oxygen species (ROS) with the assistance of nanoformulations in cancer cells via the Fenton reaction is considered an effective method to treat cancer. However, the efficiency of the Fenton reaction is affected by the level of H₂O₂, the selection of iron ions in different nanoformulations, etc. Herein, we use Fe^III-tannic acid (Fe^IIITA) nanocomposites as the carrier to deliver glucose oxidase (GOD) which can solve the problem of insufficient endogenous H₂O₂ by catalytically converting the glucose. In comparison with traditional Fe²⁺/Fe³⁺, Fe^IIITA nanocomposites perform higher catalytic activity in converting H₂O₂ to high toxic hydroxyl radicals (·OH) due to the TA-mediated reduction of Fe³⁺. So, the integration of GOD and TA in the construction of nanocomposites significantly enhances the efficiency of the Fenton reaction. In vitro experiments show that ·OH produced by GOD-Fe^IIITA nanocomposites can not only achieve a good anticancer effect at a low concentration but also promote degradability of the nanocomposites. When it is only 1.08 μg · ml^-1, the cell apoptosis rate has reached 76.91%. In vivo experiments further demonstrate that GOD-Fe^IIITA nanocomposites can significantly inhibit tumor growth. So this work lays a good foundation for Fenton reaction-based cancer treatment.

A tumor-microenvironment fully responsive nano-platform for MRI-guided photodynamic and photothermal synergistic therapy

Multifunctional intelligent theranostics agents are promising for next-generation oncotherapy.

Hollow ferric-tannic acid nanocapsules with sustained O2 and ROS induction for synergistic tumor therapy

HFe-TA nanoparticles, with a fine hollow microstructure, are synthesized and incorporated with ICG for synergistic photo/chemodynamic therapy with enhanced efficacy.

A Tailored Multifunctional Anticancer Nanodelivery System for Ruthenium-Based Photosensitizers: Tumor Microenvironment Adaption and Remodeling

Ruthenium complexes are promising photosensitizers (PSs), but their clinical applications have many limitations. Here, a multifunctional nano-platform PDA-Pt-CD@RuFc formed by platinum-decorated and cyclodextrin (CD)-modified polydopamine (PDA) nanoparticles (NPs) loaded with a ferrocene-appended ruthenium complex (RuFc) is reported. The NPs can successfully deliver RuFc to the tumor sites. The release of RuFc from the NPs can be triggered by low pH, photothermal heating, and H2O2. The combined photodynamic and photothermal therapy (PDT-PTT) mediated by PDA-Pt-CD@RuFc NPs can overcome the hypoxic environment of tumors from several aspects. First, the platinum NPs can catalyze H2O2 to produce O2. Second, vasodilation caused by photothermal heating can sustain the oxygen supplement. Third, PDT exerted by RuFc can also occur through the non-oxygen-dependent Fenton reaction. Due to the presence of PDA, platinum NPs, and RuFc, the nanosystem can be used in multimodal imaging including photothermal, photoacoustic, and computed tomography imaging. The NPs can be excited by the near-infrared two-photon light source. Moreover, the combined treatment can improve the tumor microenvironments to obtain an optimized combined therapeutic effect. In summary, this study presents a tumor-microenvironment-adaptive strategy to optimize the potential of ruthenium complexes as PSs from multiple aspects.

Ultra-small Bi2S3 nanodot-doped reversible Fe(ii/iii)-based hollow mesoporous Prussian blue nanocubes for amplified tumor oxidative stress-augmented photo-/radiotherapy

Oxidative stress imbalance could be induced by the reversible redox property of Fe(ii/iii), thereby causing DNA damage and increasing the cell membrane permeability to realize enhanced photo-/radiotherapy.

Nanoparticle facilitated delivery of peroxides for effective cancer treatments

Peroxide nanoparticles increase the intratumoral H₂O₂ concentration for the catalytic production of ˙OH and O₂, which further enhance O₂/ROS-dependent anticancer therapies.

Dancing with reactive oxygen species generation and elimination in nanotheranostics for disease treatment

Reactive oxygen species (ROS) play important roles in cell signaling and tissue homeostasis, in which the level of ROS is critical through the equilibrium between ROS generating and eliminating events. A disruption of the balance leads to disease development either by a surplus or a dearth of ROS, which requires ROS-modulating strategies to overturn the defect for disease treatment. Over the past decade, there have been tremendous advances in nanomedicine centering ROS generation and/or elimination as major mechanisms to treat a variety of diseases. In this review, we will discuss the research achievements on two opposite approaches of ROS-generating and ROS-eliminating strategies for treating cancer and other related diseases. Importantly, we will highlight the conceptual and strategic advances of ROS-mediated immunomodulation, including macrophage polarization, immunogenic cell death and T cell activation, which are currently rising as one of the mainstreams of cancer therapy. At the end, the future challenges and opportunities of mediating ROS-based mechanisms are envisioned. In light of the pleiotropic roles of ROS in different diseases, we hope this review is timely to deliver a clear logic of designing principles on ROS generation and elimination for different disease treatments.

Molecular Self-Assembly of Bioorthogonal Aptamer-Prodrug Conjugate Micelles for Hydrogen Peroxide and pH-Independent Cancer Chemodynamic Therapy

Chemodynamic therapy (CDT) has demonstrated new possibilities for selective and logical cancer intervention by specific manipulation of dysregulated tumorous free radical homeostasis. Current CDT methods largely rely on conversion of endogenous hydrogen peroxide (H₂O₂) into highly toxic hydroxyl radicals via classical Fenton or Haber-Weiss chemistry. However, their anticancer efficacies are greatly limited by the requirement of strong acidity for efficient chemical reactions, insufficient tumorous H₂O₂, and upregulated antioxidant defense to counteract free radical-caused oxidative damage. Here, we present a new concept whereby bioorthogonal chemistry and prodrug are combined to create a new type of aptamer drug conjugate (ApDC): aptamer-prodrug conjugate (ApPdC) micelle for improved and cancer-targeted CDT. The hydrophobic prodrug bases can not only promote self-assembly of aptamers but also act as free radical generators via bioorthogonal chemistry. In depth mechanistic studies reveal that, unlike traditional CDT systems, ApPdC micelles enable in situ activation and self-cycling generation of toxic C-centered free radicals in cancer cells through cascading bioorthogonal reactions, with no dependence on either H₂O₂ or pH, yet concurrently with diminished cancerous antioxidation by GSH depletion for a synergistic CDT effect. We expect this work to provide new insights into the design of targeted cancer therapies and studies of free radical-related molecular mechanisms.

Biodegradable Manganese-Doped Calcium Phosphate Nanotheranostics for Traceable Cascade Reaction-Enhanced Anti-Tumor Therapy

Glucose oxidase (GOx) has been recognized as a "star" enzyme catalyst involved in cancer treatment in the past few years. Herein, GOx is mineralized with manganese-doped calcium phosphate (MnCaP) to form spherical nanoparticles (GOx-MnCaP NPs) by an in situ biomimetic mineralization method, followed by the loading of doxorubicin (DOX) to construct a biodegradable, biocompatible, and tumor acidity-responsive nanotheranostics for magnetic resonance imaging (MRI) and cascade reaction-enhanced cooperative cancer treatment. The GOx-driven oxidation reaction can effectively eliminate intratumoral glucose for starvation therapy, and the elevated H₂O₂ is then converted into highly toxic hydroxyl radicals via a Mn²⁺-mediated Fenton-like reaction for chemodynamic therapy (CDT). Moreover, the acidity amplification due to the gluconic acid generation will in turn accelerate the degradation of the nanoplatform and promote the Mn²⁺-H₂O₂ reaction for enhanced CDT. Meanwhile, the released Mn²⁺ ions can be used for MRI to monitor the treatment process. After carrying the anticancer drug, the DOX-loaded GOx-MnCaP can integrate starvation therapy, Mn²⁺-mediated CDT, and DOX-induced chemotherapy together, which showed greatly improved therapeutic efficacy than each monotherapy. Such an orchestrated cooperative cancer therapy demonstrated high-efficiency tumor suppression on 4T1 tumor-bearing mice with minimal side effects. Our findings suggested that the DOX-loaded GOx-MnCaP nanotheranostics with excellent biodegradability and biocompatibility hold clinical translation potential for cancer management.

Self-Supply of O2 and H2O2 by a Nanocatalytic Medicine to Enhance Combined Chemo/Chemodynamic Therapy

Combined chemo/chemodynamic therapy is a promising strategy to achieve an improved anticancer effect. However, the hypoxic microenvironment and limited amount of H2O2 in most solid tumors severely restrict the efficacy of this treatment. Herein, the construction of a nanocatalytic medicine, CaO2@DOX@ZIF-67, via a bottom-up approach is described. CaO2@DOX@ZIF-67 simultaneously supplies O2 and H2O2 to achieve improved chemo/chemodynamic therapy. In the weakly acidic environment within tumors, CaO2@DOX@ZIF-67 is broken down to rapidly release the Fenton-like catalyst Co2+ and the chemotherapy drug doxorubicin (DOX). The unprotected CaO2 reacts with H2O to generate both O2 and H2O2. The generated O2 relieves the hypoxia in the tumor and further improve the efficacy of DOX. Meanwhile, the generated H2O2 reacts with Co2+ ions to produce highly toxic •OH through a Fenton-like reaction, resulting in improved chemodynamic therapy.

Recent Advances in Glucose-Oxidase-Based Nanocomposites for Tumor Therapy

Glucose oxidase (GOx) can react with intracellular glucose and oxygen (O₂ ) to produce hydrogen peroxide (H₂ O₂ ) and gluconic acid, which can cut off the nutrition source of cancer cells and consequently inhibit their proliferation. Therefore, GOx is recognised as an ideal endogenous oxido-reductase for cancer starvation therapy. This process can further regulate the tumor microenvironment by increasing the hypoxia and the acidity. Thus, GOx offers new possibilities for the elaborate design of multifunctional nanocomposites for tumor therapy. However, natural GOx is expensive to prepare and purify and exhibits immunogenicity, short in vivo half-life, and systemic toxicity. Furthermore, GOx is highly prone to degrade after exposure to biological conditions. These intrinsic shortcomings will undoubtedly limit its biomedical applications. Accordingly, some nanocarriers can be used to protect GOx from the surrounding environment, thus controlling or preserving the activity. A variety of nanocarriers including hollow mesoporous silica nanoparticles, metal-organic frameworks, organic polymers, and magnetic nanoparticles are summarized for the construction of GOx-based nanocomposites for multimodal synergistic cancer therapy. In addition, current challenges and promising developments in this area are highlighted.

Recent advancement of imidazolate framework (ZIF-8) based nanoformulations for synergistic tumor therapy

As a new kind of porous material, zeolitic imidazolate frameworks (ZIF-8) are built from zinc ions and 2-methylimidazolate and possess unique merits including high porosity, good structural regularity and tunability, adjustable surface functionality and intrinsic pH induced biodegradability. These advantages endow ZIF-8 with multiple functionalities and stimuli-responsive controlled release of loaded payloads by endogenous or exogenous means. In this review, we will summarize the recent advancement of ZIF-8 as nanocarriers for the loading of various molecules including chemotherapeutic drugs, photosensitizers, photothermal agents, and proteins to fabricate multifunctional nanocomposites for synergistic cancer therapy. In addition, the challenges and future developments in this area will be highlighted.

Recent progress in the augmentation of reactive species with nanoplatforms for cancer therapy

Reactive species (RS), mainly including reactive oxygen species (ROS) and reactive nitrogen species (RNS), are indispensable in a wide variety of biological processes. RS often have elevated levels in cancer cells and tumor microenvironments. They also have a dual effect on cancer: on the one hand, they promote pro-tumorigenic signaling to facilitate tumor survival and on the other hand, they promote antitumorigenic pathways to induce cell death. Excessive RS would disrupt the cellular redox homeostasis balance and show partiality as oxidants, which would cause irreversible damage to the adjacent biomolecules such as lipids, proteins and nucleic acids. The altered redox environment and the corresponding increased antioxidant capacity in cancer cells render the cells susceptible to RS-manipulated therapies, especially the augmentation of RS. With the rapid development of nanotechnology and nanomedicine, a large number of cancer therapeutic nanoplatforms have been developed to trigger RS overproduction by exogenous and/or endogenous stimulation. In this review, we highlighted the latest progress in the nanoplatforms designed for the augmentation of RS in cancer therapy. Nanoplatforms based on strategies including disabling the antioxidant defense system, photodynamic therapy (PDT), sonodynamic therapy (SDT), and chemodynamic therapy (CDT) were introduced. The crucial obstacles involved in these strategies, such as the light penetration limitation of PDT, relatively low RS release by SDT, and strict conditions of Fenton reaction-mediated CDT, were also discussed, and feasible solutions for improvement were proposed. Furthermore, synergistic therapies among individual therapeutic modalities such as chemotherapy, photothermal therapy, and RS-based dynamic therapies were overviewed, which contributed to achieving more optimal anticancer efficacy than linear addition. This review sheds light on the development of non-invasive cancer therapy based on RS manipulation and provides guidance for establishing promising cancer therapeutic platforms in clinical settings.

Manganese-Based Nanoplatform As Metal Ion-Enhanced ROS Generator for Combined Chemodynamic/Photodynamic Therapy

Reactive oxygen species (ROS) with strong oxidizing and high activity have been regarded as an effective "weapon" for antitumor therapy, since it can induce organelle injury, oxidative damage, and cell death. Herein, hollow structured manganese carbonate (MnCO₃) nanocubes are fabricated and loaded with photosensitizer (chlorin e6, Ce6), obtaining a responsive nanoplatform H-MnCO₃/Ce6-PEG (HMCP NCs). Two different approaches to upregulate intracellular ROS level were realized by HMCP NCs. On one hand, with irradiation of external laser, Ce6 could generate singlet oxygen (¹O₂) through a multistep photochemical process applied in photodynamic therapy (PDT). On the other hand, MnCO₃ could be specifically degraded into Mn²⁺ in an acidic tumor microenvironment (TME), triggering Mn²⁺-activated Fenton-like reaction to convert endogenous H₂O₂ into hydroxyl radical (•OH). In vitro combined chemodynamic therapy (CDT) and PDT showed that the metal ion-enhanced ROS production could break the intracellular redox equilibrium, thus leading to cell death. In vivo combined CDT/PDT with HMCP NCs exhibited remarkably enhanced therapeutic efficacy in inhibiting tumor growth, without resulting in noticeable damage to normal tissues. This work presents a unique type of manganese-based nanoplatform for efficiently generating ROS in solid tumors, favorable for ROS-involved therapeutic strategies.

Catalytically Selective Chemotherapy from Tumor-Metabolic Generated Lactic Acid

Lactic acid (LA) is a powerful molecule as the metabolic driver in tumor microenvironments (TMEs). Inspired by its high intratumoral level (5-20 µmol g^-1 ), a novel treatment paradigm via the cascade release of H₂ O₂ and ·OH from the LA generated by tumor metabolism is developed for catalytic and pH-dependent selective tumor chemotherapy. By utilizing the acidity and overexpression of LA within the TME, the constructed lactate oxidase (LOD)-immobilized Ce-benzenetricarboxylic acid (Ce-BTC) metal organic framework enables the intratumoral generation of ·OH via a cascade reaction: 1) the in situ catalytic release of H₂ O₂ from LA by LOD, and 2) the catalytic production of ·OH from H₂ O₂ by Ce-BTC with peroxidase-like activity. Highly toxic ·OH effectively induces tumor apoptosis/death. A new strategy for selective tumor chemotherapy is provided herein.

Mo2 C-Derived Polyoxometalate for NIR-II Photoacoustic Imaging-Guided Chemodynamic/Photothermal Synergistic Therapy

To overcome the current limitations of chemodynamic therapy (CDT), a Mo₂ C-derived polyoxometalate (POM) is readily synthesized as a new CDT agent. It permits synergistic chemodynamic and photothermal therapy operating in the second near-infrared (NIR-II) biological transparent window for deep tissue penetration. POM aggregated in an acidic tumor micro-environment (TME) whereby enables specific tumor targeting. In addition to the strong ability to produce singlet oxygen (¹ O₂ ) presumably via Russell mechanism, its excellent photothermal conversion enhances the CDT effect, offers additional tumor ablation modality, and permits NIR-II photoacoustic imaging. Benefitting from the reversible redox property of molybdenum, the theranostics based on POM can escape from the antioxidant defense system. Moreover, combining the specific responsiveness to TME and localized laser irradiation, side-effects shall be largely avoided.

Au@Prussian Blue Hybrid Nanomaterial Synergy with a Chemotherapeutic Drug for Tumor Diagnosis and Chemodynamic Therapy

Recently, the chemodynamic therapy (CDT) has been widely reported and applied to tumor therapy. However, only low level hydroxyl radicals (^•OH) generated by the endogenous hydrogen peroxide alone are insufficient to kill the cancer cells. To overcome the insufficient therapeutic effect, this study reports a novel CDT based on Fenton catalyst Au@Prussian blue nanocubes (Au@PB NCs), subsequently encapsulated with doxorubicin (Dox). The in vitro and in vivo results indicate that the Dox-Au@PB NCs can take synergistic effects on tumor suppressor by CDT. In addition, Au@PB NCs possess high X-ray computed tomography contrast enhanced efficiency about ∼27.13 HU·mL·mg^-1. This study highlights a great potential of the Dox-Au@PB NCs for tumor diagnosis and CDT.

O2-Generating Metal-Organic Framework-Based Hydrophobic Photosensitizer Delivery System for Enhanced Photodynamic Therapy

Photodynamic therapy (PDT) has been introduced as a photochemical process for treatment by causing cancer cell death and necrosis, with higher accuracy and few side effects. However, the hydrophobicity of most photosensitizers and hypoxia at the tumor sites are two crucial problems to be solved to achieve a successful PDT. Herein, we designed and constructed a novel metal-organic framework-based drug delivery system (BSA-MnO₂/Ce6@ZIF-8) with tumor microenvironment controllability. In our system, the hydrophobic photosensitizer chlorin e6 (Ce6) was one-pot incorporated into the matrix of zeolitic imidazolate framework 8 (ZIF-8) to form the Ce6@ZIF-8 compound, which can efficiently keep the Ce6 molecules isolated and avoid them self-aggregate, and the loading rate of Ce6 was high up to 28.3 wt %. The bovine serum albumin (BSA)-MnO₂ nanoparticles (NPs) with catalase-like activity were loaded onto the surface of ZIF-8, having the capacity for self-sufficiency of O₂ under the circumstance of H₂O₂ in acid solution, relieving hypoxia in cancer cells and thereby improving the PDT efficiency greatly when irradiated by low power density (230 mW/cm²) 650 nm light. Moreover, the MnO₂ NPs react with H₂O₂ in acid solution to produce Mn²⁺, granting the system the qualification of a contrast agent for magnetic resonance imaging. Therefore, our nanoplatform would further contribute to the treatment of hypoxic tumors in clinical practice.

Synthesis of Ultrathin Biotite Nanosheets as an Intelligent Theranostic Platform for Combination Cancer Therapy

Biotite, also called black mica (BM), is a group of sheet silicate minerals with great potential in various fields. However, synthesis of high-quality BM nanosheets (NSs) remains a huge challenge. Here, an exfoliation approach is provided that combines calcination, n-butyllithium exchange and intercalation, and liquid exfoliating processes for the high-yield synthesis of ultrathin BM NSs. Due to the presence of MgO, Fe2O3, and FeO in these NSs, PEGylated BM can be engineered as an intelligent theranostic platform with the following unique features: i) Fe3+ can damage the tumor microenvironment (TME) through glutathione consumption and O2 production; ii) Generated O2 can be further catalyzed by MgO with oxygen vacancy to generate ·O2 -; iii) The Fe2+-catalyzed Fenton reaction can produce ·OH by disproportionation reactions of H2O2 in the TME; iv) Reactions in (i) and (iii) circularly regenerate Fe2+ and Fe3+ for continuous consumption of glutathione and H2O2 and constant production of ·OH and O2; v) The NSs can be triggered by a 650 nm laser to generate ·O2 - from O2 as well as by an 808 nm laser to generate local hyperthermia; and vi) The fluorescent, photoacoustic, and photothermal imaging capabilities of the engineered NSs allow for multimodal imaging-guided breast cancer treatment.

Fabrication of H2O2-driven nanoreactors for innovative cancer treatments

The increased production of hydrogen peroxide (H₂O₂) is a typical feature of cancerous cells. This feature is closely associated with elevated oxidative stress inside solid tumour microenvironments, which thus impairs either the growth of cancer cells or their sensitivity to many cancer therapeutics. To date, numerous innovative strategies that target tumour H₂O₂ have been designed for effective cancer treatment. More recently, with the rapid advancement of nanomedicine, several nanoreactors, which are highly efficient in converting endogenous H₂O₂ to more toxic reactive oxygen species, promoting in situ H₂O₂, or decomposing endogenous H₂O₂ to molecular oxygen for tumour hypoxia attenuation, have been designed and attempted for effective cancer treatment. This review focuses on the latest progress of such innovative H₂O₂-driven nanoreactor-mediated cancer treatments. Afterwards, future perspectives on the development of tumour H₂O₂-driven nanoreactor-mediated cancer treatments and their potential clinical translations will be discussed.

Programmed degradation of a hierarchical nanoparticle with redox and light responsivity for self-activated photo-chemical enhanced chemodynamic therapy

Chemodynamic therapy (CDT) has recently emerged as a promising treatment for cancer due to the high specificity of CDT towards tumor microenvironment (TME). However, the low efficiency of reactive oxygen species (ROS) generation and the robust ROS defensive mechanisms in cancer cells remain critical hurdles for current CDT. Addressing both challenges in a single platform, we developed a novel redox and light-responsive (RLR) nanoparticle with a core-shell structure. Remarkably, our hierarchical RLR nanoparticle is composed of an ultrasmall Fe₃O₄ nanoparticle engineered framework of hollow carbon matrix core and a nanoflower-like MnO₂ shell. Under the abundant overexpressed glutathione (GSH) and acidic nature in TME, the RLR nanoparticle was programmed to degrade and self-activate CDT-induced cancer-killing by accelerating ROS generation via overcoming the ROS defensive mechanisms based on the depletion of intracellular GSH, the sequential production of theranostic ion species (e.g., Mn²⁺ and Fe²⁺), a spatiotemporal controllable photothermal hyperthermia and a redox triggered chemotherapeutic drug release. Additionally, the carbon framework of RLR nanoparticle could collapse by leaching of iron ions. An excellent selective and near-complete tumor suppression based on the RLR nanoparticles through a strong synergy between CDT, PTT and anti-cancer drugs was demonstrated via in vitro and in vivo anti-tumoral assays.

Multifunctional Magnetic Copper Ferrite Nanoparticles as Fenton-like Reaction and Near-Infrared Photothermal Agents for Synergetic Antibacterial Therapy

Synergistic therapeutic strategies for bacterial infection have attracted extensive attentions owing to their enhanced therapeutic effects and less adverse effects compared with monotherapy. Herein, we report a novel synergistic antibacterial platform that integrates the nanocatalytic antibacterial therapy and photothermal therapy (PTT) by hemoglobin-functionalized copper ferrite nanoparticles (Hb-CFNPs). In the presence of a low concentration of hydrogen peroxide (H₂O₂), the excellent Fenton and Fenton-like reaction activity of Hb-CFNPs can effectively catalyze the decomposition of H₂O₂ to produce hydroxyl radicals (·OH), rendering an increase in the permeability of the bacterial cell membrane and the sensitivity to heat. With the assistance of NIR irradiation, hyperthermia generated by Hb-CFNPs can induce the death of the damaged bacteria. Additionally, owing to the outstanding magnetic property of Hb-CFNPs, it can improve the photothermal efficiency by about 20 times via magnetic enrichment, which facilitates to realize excellent bactericidal efficacy at a very low experimental dose (20 μg/mL). In vitro antibacterial experiment shows that this synergistic antibacterial strategy has a broad-spectrum antibacterial property against Gram-negative Escherichia coli (E. coli, 100%) and Gram-positive Staphylococcus aureus (S. aureus, 96.4%). More importantly, in vivo S. aureus-infected abscess treatment studies indicate that Hb-CFNPs can serve as an antibacterial candidate with negligible toxicity to realize synergistic treatment of bacterial infections through catalytic and photothermal effects. Accordingly, this study proposes a novel, high-efficiency, and multifunctional therapeutic system for the treatment of bacterial infection, which will open up a new avenue for the design of synergistic antibacterial systems in the future.

Enhanced Antitumor Efficacy by a Cascade of Reactive Oxygen Species Generation and Drug Release

Reactive oxygen species (ROS) can be used not only as a therapeutic agent for chemodynamic therapy (CDT), but also as a stimulus to activate release of antitumor drugs, achieving enhanced efficacy through the combination of CDT and chemotherapy. Here we report a pH/ROS dual-responsive nanomedicine consisting of β-lapachone (Lap), a pH-responsive polymer, and a ROS-responsive polyprodrug. In the intracellular acidic environment, the nanomedicine can realize pH-triggered disassembly. The released Lap can efficiently generate hydrogen peroxide, which will be further converted into highly toxic hydroxyl radicals via the Fenton reaction. Subsequently, through ROS-induced cleavage of thioketal linker, doxorubicin is released from the polyprodrug. In vivo results indicate that the cascade of ROS generation and antitumor-drug release can effectively inhibit tumor growth. This design of nanomedicine with cascade reactions offers a promising strategy to enhance antitumor efficacy.

Nanocatalytic Medicine

Catalysis and medicine are often considered as two independent research fields with their own respective scientific phenomena. Promoted by recent advances in nanochemistry, large numbers of nanocatalysts, such as nanozymes, photocatalysts, and electrocatalysts, have been applied in vivo to initiate catalytic reactions and modulate biological microenvironments for generating therapeutic effects. The rapid growth of research in biomedical applications of nanocatalysts has led to the concept of "nanocatalytic medicine," which is expected to promote the further advance of such a subdiscipline in nanomedicine. The high efficiency and selectivity of catalysis that chemists strived to achieve in the past century can be ingeniously translated into high efficacy and mitigated side effects in theranostics by using "nanocatalytic medicine" to steer catalytic reactions for optimized therapeutic outcomes. Here, the rationale behind the construction of nanocatalytic medicine is eludicated based on the essential reaction factors of catalytic reactions (catalysts, energy input, and reactant). Recent advances in this burgeoning field are then comprehensively presented and the mechanisms by which catalytic nanosystems are conferred with theranostic functions are discussed in detail. It is believed that such an emerging catalytic therapeutic modality will play a more important role in the field of nanomedicine.

Fenton Reaction-Assisted Photodynamic Therapy for Cancer with Multifunctional Magnetic Nanoparticles

Tumor hypoxia and the short half-life of reactive oxygen species (ROS) with small diffusion distance have greatly limited the therapeutic effect of photodynamic therapy (PDT). Here, a multifunctional nanoplatform is developed to enhance the PDT effect through increasing the oxygen concentration in tumor cells by the Fenton reaction and reducing the distance between the ROS and the target site by mitochondrial targeting. Fe₃O₄@Dex-TPP nanoparticles are first prepared by coprecipitation in the presence of triphenylphosphine (TPP)-grafted dextran (Dex-TPP) and Fe²⁺/Fe³⁺, which have a magnetic resonance imaging effect. Next, the photosensitizers of protoporphyrin IX (PpIX) and glutathione-responsive mPEG-ss-COOH are grafted on Fe₃O₄@Dex-TPP to form Fe₃O₄@Dex/TPP/PpIX/ss-mPEG nanoparticles. After the nanoparticles are internalized, part of Fe₃O₄ are decomposed into Fe²⁺/Fe³⁺ in the acidic lysosome and then Fe²⁺/Fe³⁺ diffused into the cytoplasm, and subsequently, Fe²⁺ reacted with the overproduced H₂O₂ to produce O₂ and ^•OH. The undecomposed nanoparticles enter the cytoplasm by photoinduced internalization and targeted to the mitochondria, leading to ROS direct generation around the mitochondria. Simultaneously, the produced O₂ by the Fenton reaction can serve as a raw material for PDT to continuously exert PDT effect. As a result, the Fenton reaction-assisted PDT can significantly improve the therapeutic efficacy of tumors.

Interfacial engineered gadolinium oxide nanoparticles for magnetic resonance imaging guided microenvironment-mediated synergetic chemodynamic/photothermal therapy

Engineering interfacial structure of biomaterials have drawn much attention due to it can improve the diagnostic accuracy and therapy efficacy of nanomedicine, even introducing new moiety to construct theranostic agents. Nanosized magnetic resonance imaging contrast agent holds great promise for the clinical diagnosis of disease, especially tumor and brain disease. Thus, engineering its interfacial structure can form new theranostic platform to achieve effective disease diagnosis and therapy. In this study, we engineered the interfacial structure of typical MRI contrast agent, Gd₂O₃, to form a new theranostic agent with improved relaxivity for MRI guided synergetic chemodynamic/photothermal therapy. The synthesized Mn doped gadolinium oxide nanoplate exhibit improved T₁ contrast ability due to large amount of efficient paramagnetic metal ions and synergistic enhancement caused by the exposed Mn and Gd cluster. Besides, the introduced Mn element endow this nanomedicine with the Fenton-like ability to generate OH from excess H₂O₂ in tumor site to achieve chemodynamic therapy (CDT). Furthermore, polydopamine engineered surface allow this nanomedicine with effective photothermal conversion ability to rise local temperature and accelerate the intratumoral Fenton process to achieve synergetic CDT/photothermal therapy (PTT). This work provides new guidance for designing magnetic resonance imaging guided synergetic CDT/PTT to achieve tumor detection and therapy.

Promoting Oxidative Stress in Cancer Starvation Therapy by Site-Specific Startup of Hyaluronic Acid-Enveloped Dual-Catalytic Nanoreactors

Cutting off the glucose supply by glucose oxidase (GOx) has been regarded as an emerging strategy in cancer starvation therapy. However, the standalone GOx delivery suffered suboptimal potency for tumor elimination and potential risks of damaging vasculatures and normal organs during transportation. To enhance therapeutic efficacy and tumor specificity, a site-specific activated dual-catalytic nanoreactor was herein constructed by embedding GOx and ferrocene in hyaluronic acid (HA)-enveloped dendritic mesoporous silica nanoparticles to promote intratumoral oxidative stress in cancer starvation. In this nanoreactor, the encapsulated GOx served as the primary catalyst that accelerated oxidation of glucose and generation of H₂O₂, while the covalently linked ferrocene worked as the secondary catalyst for converting the upstream H₂O₂ to more toxic hydroxyl radicals (^•OH) via a classic Fenton reaction. The outmost HA shell not only offered a shielding layer for preventing blood glucose from oxidation during nanoreactor transportation, thus minimizing the probable oxidative damage to normal tissues, but also imparted the nanoreactor with targeting ability for facilitating its internalization into CD44-overexpressing tumor cells. After the nanoreactor was endocytosed by target cells, the HA shell underwent hyaluronidase-triggered degradation in lysosomes and switched on the cascade catalytic reaction mediated by GOx and ferrocene. The resulting glucose exhaustion and ^•OH accumulation would effectively kill cancer cells and suppress tumor growth via combination of starvation and oxidative stress enhancement. Both in vitro and in vivo results indicated the significantly amplified therapeutic effects of this synergistic therapeutic strategy based on the dual-catalytic nanoreactor. Our study provides a new avenue for engineering therapeutic nanoreactors that take effect in a tumor-specific and orchestrated fashion for cancer starvation therapy.

Clearable Theranostic Platform with a pH-Independent Chemodynamic Therapy Enhancement Strategy for Synergetic Photothermal Tumor Therapy

Chemodynamic therapy (CDT) is an emerging field, which utilizes intratumoral iron-mediated Fenton chemistry for cancer therapy. However, the slightly acidic tumor environment is improper for the classical Fenton reaction, which is generally energetic in a narrow pH range (e.g., pH = 3-4). Herein, a kind of ultrasmall bovine serum albumin (BSA)-modified chalcopyrite nanoparticles (BSA-CuFeS₂ NPs) was synthesized via a facile aqueous biomineralization strategy, which shows high dispersity and biocompatibility. Interestingly, the obtained BSA-CuFeS₂ shows a pH-independent Fenton-like reaction, which could exert Fenton-like activity to efficiently generate ^•OH under a weak acidic tumor environment. Combined with the extraordinarily high photothermal conversion (38.8%), BSA-CuFeS₂ shows the synergistic function of high photothermal therapy (PTT) and enhanced CDT, that is, PTT/CDT. Importantly, such ultrasmall BSA-CuFeS₂ NPs measuring around 4.9 nm can be quickly cleared out of the body through kidneys and liver, thus effectively avoiding long-term toxicity and systemic toxicity. Moreover, BSA-CuFeS₂ NPs can act as an efficient T₂-weighted magnetic resonance imaging (MRI) contrast agent to guide tumor ablation in vivo. This work offers a universal approach to boost production ^•OH by a pH-independent Fenton-like reaction strategy and achieves MRI-guided synergistic enhanced photothermal-CDT for highly efficient tumor treatment.

Biodegradable Biomimic Copper/Manganese Silicate Nanospheres for Chemodynamic/Photodynamic Synergistic Therapy with Simultaneous Glutathione Depletion and Hypoxia Relief

The integration of reactive oxygen species (ROS)-involved photodynamic therapy (PDT) and chemodynamic therapy (CDT) holds great promise for enhanced anticancer effects. Herein, we report biodegradable cancer cell membrane-coated mesoporous copper/manganese silicate nanospheres (mCMSNs) with homotypic targeting ability to the cancer cell lines and enhanced ROS generation through singlet oxygen (¹O₂) production and glutathione (GSH)-activated Fenton reaction, showing excellent CDT/PDT synergistic therapeutic effects. We demonstrate that mCMSNs are able to relieve the tumor hypoxia microenvironment by catalytic decomposition of endogenous H₂O₂ to O₂ and further react with O₂ to produce toxic ¹O₂ with a 635 nm laser irradiation. GSH-triggered mCMSNs biodegradation can simultaneously generate Fenton-like Cu⁺ and Mn²⁺ ions and deplete GSH for efficient hydroxyl radical (•OH) production. The specific recognition and homotypic targeting ability to the cancer cells were also revealed. Notably, relieving hypoxia and GSH depletion disrupts the tumor microenvironment (TME) and cellular antioxidant defense system, achieving exceptional cancer-targeting therapeutic effects in vitro and in vivo. The cancer cells growth was significantly inhibited. Moreover, the released Mn²⁺ can also act as an advanced contrast agent for cancer magnetic resonance imaging (MRI). Thus, together with photosensitizers, Fenton agent provider and MRI contrast effects along with the modulating of the TME allow mCMSNs to realize MRI-monitored enhanced CDT/PDT synergistic therapy. It provides a paradigm to rationally design TME-responsive and ROS-involved therapeutic strategies based on a single polymetallic silicate nanomaterial with enhanced anticancer effects.

Combined Fenton and starvation therapies using hemoglobin and glucose oxidase

Separately, Fenton and starvation cancer therapies have been recently reported as impressive methods for tumor destruction. Here, we introduce natural hemoglobin and glucose oxidase (GOx) for efficient cancer treatment following combined Fenton and starvation therapies. GOx and hemoglobin were encapsulated in zeolitic imidazolate frameworks 8 (ZIF-8) to fabricate a pH-sensitive MOF activated by tumor acidity. In the slightly acidic environment of cancer cells, GOx is released and it consumes d-glucose and molecular oxygen, nutrients essential for the survival of cancer cells, and produces gluconic acid and hydrogen peroxide, respectively. The produced gluconic acid increases the acidity of the tumor microenvironment leading to complete MOF destruction and enhances hemoglobin and GOx release. The Fe ions from the heme groups of hemoglobin also release in the presence of both endogenous and produced H2O2 and generate hydroxyl radicals. The produced OH˙ radical can rapidly oxidize the surrounding biomacromolecules in the biological system and treat the cancer cells. In vitro experiments demonstrate that this novel nanoparticle is cytotoxic to cancer cells HeLa and MCF-7, at very low concentrations (<2 μg mL-1). In addition, the selectivity index values are 5.52 and 11.04 for HeLa and MCF-7 cells, respectively, which are much higher than those of commercial drugs and those of similar studies reported by other research groups. This work thus demonstrates a novel pH-sensitive system containing hemoglobin and GOx for effective and selective cancer treatment using both radical generation and nutrient starvation.

Self-evolved hydrogen peroxide boosts photothermal-promoted tumor-specific nanocatalytic therapy

Highly efficient nanocatalytic tumor therapy has been achieved by in situ self-supplied H₂O₂-triggered and photothermally-promoted Fenton reaction by the rational design of two-dimensional composite nanoreactors.