Nanozyme-Initiated In Situ Cascade Reactions for Self-Amplified Biocatalytic Immunotherapy

FeSA‐Ir/Metallene Nanozymes Induce Sequential Ferroptosis‐Pyroptosis for Multi‐Immunogenic Responses Against Lung Metastasis

For cancer metastasis inhibition, the combining of nanozymes with immune checkpoint blockade (ICB) therapy remains the major challenge in controllable reactive oxygen species (ROS) generation for creating effective immunogenicity. Herein, new nanozymes with light-controlled ROS production in terms of quantity and variety are developed by conjugating supramolecular-wrapped Fe single atom on iridium metallene with lattice-strained nanoislands (FeSA-Ir@PF NSs). The Fenton-like catalysis of FeSA-Ir@PF NSs effectively produced •OH radicals in dark, which induced ferroptosis and apoptosis of cancer cells. While under second near-infrared (NIR-II) light irradiation, FeSA-Ir@PF NSs showed ultrahigh photothermal conversion efficiency (𝜂, 75.29%), cooperative robust •OH generation, photocatalytic O2 and 1O2 generation, and caused significant pyroptosis of cancer cells. The controllable ROS generation, sequential cancer cells ferroptosis and pyroptosis, led 99.1% primary tumor inhibition and multi-immunogenic responses in vivo. Most importantly, the inhibition of cancer lung metastasis is completely achieved by FeSA-Ir@PF NSs with immune checkpoint inhibitors, as demonstrated in different mice lung metastasis models, including circulating tumor cells (CTCs) model. This work provided new inspiration for developing nanozymes for cancer treatments and metastasis inhibition.

Nanozymes-Mediated Cascade Reaction System for Tumor-Specific Diagnosis and Targeted Therapy

Cascade reactions are described as efficient and versatile tools, and organized catalytic cascades can significantly improve the efficiency of chemical interworking between nanozymes. They have attracted great interest in many fields such as chromogenic detection, biosensing, tumor diagnosis, and therapy. However, how to selectively kill tumor cells by enzymatic reactions without harming normal cells, as well as exploring two or more enzyme-engineered nanoreactors for cascading catalytic reactions, remain great challenges in the field of targeted and specific cancer diagnostics and therapy. The latest research advances in nanozyme-catalyzed cascade processes for cancer diagnosis and therapy are described in this article. Here, various sensing strategies are summarized, for tumor-specific diagnostics. Targeting mechanisms for tumor treatment using cascade nanozymes are classified and analyzed, "elements" and "dimensions" of cascade nanozymes, types, designs of structure, and assembly modes of highly active and specific cascade nanozymes, as well as a variety of new strategies of tumor targeting based on the cascade reaction of nanozymes. Finally, the integrated application of the cascade nanozymes systems in tumor-targeted and specific diagnostic therapy is summarized, which will lay the foundation for the design of more rational, efficient, and specific tumor diagnostic and therapeutic modalities in the future.

Nanozymes with biomimetically designed properties for cancer treatment

Nanozymes, as a type of nanomaterials with enzymatic catalytic activity, have demonstrated tremendous potential in cancer treatment owing to their unique biomedical properties. However, the heterogeneity of tumors and the complex tumor microenvironment pose significant challenges to the in vivo catalytic efficacy of traditional nanozymes. Drawing inspiration from natural enzymes, scientists are now using biomimetic design to build nanozymes from the ground up. This approach aims to replicate the key characteristics of natural enzymes, including active structures, catalytic processes, and the ability to adapt to the tumor environment. This achieves selective optimization of nanozyme catalytic performance and therapeutic effects. This review takes a deep dive into the use of these biomimetically designed nanozymes in cancer treatment. It explores a range of biomimetic design strategies, from structural and process mimicry to advanced functional biomimicry. A significant focus is on tweaking the nanozyme structures to boost their catalytic performance, integrating them into complex enzyme networks similar to those in biological systems, and adjusting functions like altering tumor metabolism, reshaping the tumor environment, and enhancing drug delivery. The review also covers the applications of specially designed nanozymes in pan-cancer treatment, from catalytic therapy to improved traditional methods like chemotherapy, radiotherapy, and sonodynamic therapy, specifically analyzing the anti-tumor mechanisms of different therapeutic combination systems. Through rational design, these biomimetically designed nanozymes not only deepen the understanding of the regulatory mechanisms of nanozyme structure and performance but also adapt profoundly to tumor physiology, optimizing therapeutic effects and paving new pathways for innovative cancer treatment.

Effect of Phosphorus Modulation in Iron Single-Atom Catalysts for Peroxidase Mimicking

Fe-N-C single-atom catalysts (SACs) exhibit excellent peroxidase (POD)-like catalytic activity, owing to their well-defined isolated iron active sites on the carbon substrate, which effectively mimic the structure of natural peroxidase's active center. To further meet the requirements of diverse biosensing applications, SAC POD-like activity still needs to be continuously enhanced. Herein, a phosphorus (P) heteroatom is introduced to boost the POD-like activity of Fe-N-C SACs. A 1D carbon nanowire (FeNCP/NW) catalyst with enriched Fe-N4 active sites is designed and synthesized, and P atoms are doped in the carbon matrix to affect the Fe center through long-range interaction. The experimental results show that the P-doping process can boost the POD-like activity more than the non-P-doped one, with excellent selectivity and stability. The mechanism analysis results show that the introduction of P into SAC can greatly enhance POD-like activity initially, but its effect becomes insignificant with increasing amount of P. As a proof of concept, FeNCP/NW is employed in an enzyme cascade platform for highly sensitive colorimetric detection of the neurotransmitter acetylcholine.

A new era in cancer treatment: harnessing ZIF-8 nanoparticles for PD-1 inhibitor delivery

This review delves into the potential of zeolitic imidazolate framework-8 (ZIF-8) nanoparticles in augmenting the efficacy of cancer immunotherapy, with a special focus on the delivery of programmed cell death receptor 1 (PD-1) inhibitors. The multifunctional nature of ZIF-8 nanoparticles as drug carriers is emphasized, with their ability to encapsulate a range of therapeutic agents, including PD-1 inhibitors, and facilitate their targeted delivery to tumor locations. By manipulating the pore size and surface characteristics of ZIF-8 nanoparticles, controlled drug release can be realized. The strategic use of ZIF-8 nanoparticles to deliver PD-1 inhibitors presents a precise and targeted modality for cancer treatment, reducing off-target impacts and enhancing therapeutic effectiveness. This combined strategy addresses the existing challenges and constraints of current immunotherapy techniques, with the ultimate goal of enhancing patient outcomes in cancer therapy.

Nanotechnology Utilizing Ferroptosis Inducers in Cancer Treatment

Current cancer treatment options have presented numerous challenges in terms of reaching high efficacy. As a result, an immediate step must be taken to create novel therapies that can achieve more than satisfying outcomes in the fight against tumors. Ferroptosis, an emerging form of regulated cell death (RCD) that is reliant on iron and reactive oxygen species, has garnered significant attention in the field of cancer therapy. Ferroptosis has been reported to be induced by a variety of small molecule compounds known as ferroptosis inducers (FINs), as well as several licensed chemotherapy medicines. These compounds' low solubility, systemic toxicity, and limited capacity to target tumors are some of the significant limitations that have hindered their clinical effectiveness. A novel cancer therapy paradigm has been created by the hypothesis that ferroptosis induced by nanoparticles has superior preclinical properties to that induced by small drugs and can overcome apoptosis resistance. Knowing the different ideas behind the preparation of nanomaterials that target ferroptosis can be very helpful in generating new ideas. Simultaneously, more improvement in nanomaterial design is needed to make them appropriate for therapeutic treatment. This paper first discusses the fundamentals of nanomedicine-based ferroptosis to highlight the potential and characteristics of ferroptosis in the context of cancer treatment. The latest study on nanomedicine applications for ferroptosis-based anticancer therapy is then highlighted.

Biomimetic inducer enabled dual ferroptosis of tumor and M2-type macrophages for enhanced tumor immunotherapy

Tumor-associated macrophages (TAMs) are abundant in the tumor microenvironment which promotes the formation of the immunosuppressive tumor microenvironment (ITME) through multiple mechanisms, severely counteracting the therapeutic efficacy of immunotherapy. In this study, a novel biomimetic ferroptosis inducer (D@FMN-M) capable of ITME regulation for enhanced cancer ferroptosis immunotherapy is reported. Upon tumor accumulation of D@FMN-M, the intratumoral mild acidity triggers the biodegradation of Fe-enriched nanocarriers and the concurrent co-releases of dihydroartemisinin (DHA) and Fe3+. The released Fe3+ is reduced to Fe2+ by consuming intratumoral glutathione (GSH), which promotes abundant free radical generation via triggering Fenton and Fe2+-DHA reactions, thus inducing ferroptosis of both cancer cells and M2-type TAMs. Resultantly, the anticancer immune response is strongly activated by the massive tumor-associated antigens released by ferroptositic cancer cells. Also importantly, the ferroptosis-sensitive M2-type TAMs will be either damaged or gradually domesticated to ferroptosis-resistant M1 TAMs under the ferroptosis stress, favoring the normalization of ITME and finally amplifying cancer ferroptosis immunotherapeutic efficacy. This work provides a novel strategy for ferroptosis immunotherapy of solid tumors featuring TAMs infiltration and immunosuppression by inducing dual ferroptosis of tumor cells and M2-type TAMs.

Multiple therapeutic mechanisms of pyrrolic N-rich g-C3N4 nanosheets with enzyme-like function in the tumor microenvironment

Nanozyme-based synergistic catalytic therapies for tumors have attracted extensive research attention. However, the unsatisfactory efficiency and negative impact of the tumor microenvironment (TME) hinder its clinical applications. In this study, we provide an easy method to prepare transition metals loaded onto pyrrolic nitrogen-rich g-C3N4 (PN-g-C3N4) for forming metal-N4 sites. This N-rich material effectively transfers electrons from g-C3N4 to metal-N4 sites, promotes the oxidation-reduction reaction of metals with different valence states, and improves material reusability. Under TME conditions, copper ions loaded onto PN-g-C3N4 (Cu-PN-g-C3N4, CPC) can produce ·OH through a Fenton-like reaction for tumor inhibition. This Fenton-like reaction and tumor cell inhibition can be improved further by a photodynamic effect caused by light irradiation. We introduced upconversion nanoparticles (UCNPs) into CPC to obtain nano-enzymes (UCNPs@Cu-PN-g-C3N4, UCPC) for effectively penetrating the tissue, which emits light corresponding to the UV absorption region of CPC when excited with 980 nm near-infrared (NIR) light. The nanoplatform can reduce H2O2 concentration upon exposure to NIR light; this induces an increase in dissolved oxygen content and produces a higher supply of reactive oxygen species (ROS) for destroying tumor cells. Owing to the narrow bandgap (1.92 eV) of UCPC under 980 light irradiation, even under the condition of hypoxia, the excited electrons in the conduction band can reduce insoluble O2 through a single electron transfer process, thus effectively generating O2•-. Nanoenzyme materials with catalase properties produce three types of ROS (·OH, O2•- and 1O2) when realizing chemodynamic and photodynamic therapies. An excellent therapeutic effect was established by killing cells in vitro and the tumor-inhibiting effect in vivo, proving that the prepared nanoenzymes have an effective therapeutic effect and that the endogenous synergistic treatment of multiple treatment technologies can be realized.

Nonferrous Ferroptosis Inducer Manganese Molybdate Nanoparticles to Enhance Tumor Immunotherapy

Tumor immunotherapy is an important tool in oncology treatment. However, only a small percentage of patients have an effective immune response to tumor immunotherapy due to the poor infiltration of pro-inflammatory immune cells in immune "cold" tumors and an immunosuppressive network in the tumor microenvironment (TME). Ferroptosis has been widely used as a novel strategy to enhance tumor immunotherapy. Herein, manganese molybdate nanoparticles (MnMoOx NPs) depleted the highly expressed glutathione (GSH) in tumors and inhibited glutathione peroxidase 4 (GPX4) expression, thus triggering ferroptosis, inducing immune cell death (ICD), further releasing damage-associated molecular patterns (DAMPs), and enhancing tumor immunotherapy. Furthermore, MnMoOx NPs can efficiently suppress tumors, promote the maturation of dendritic cells (DCs), infiltrate T cells, and reverse the immunosuppressive microenvironment, making the tumor an immune "hot" tumor. Combination with an immune checkpoint inhibitor (ICI) (α-PD-L1) further enhanced the anti-tumor effect and inhibited metastases as well. The work provides a new idea for the development of nonferrous inducers of ferroptosis to enhance cancer immunotherapy.

Integrated supramolecular nanovalves for photothermal augmented chemodynamic therapy through strengthened amplification of oxidative stress

The amplified oxidative stress strategy has been emerged as one promising method to enhance the chemodynamic therapy (CDT) efficacy due to the H₂O₂ up-regulation and glutathione (GSH) down-regulation behavior in tumor cells. However, how to further achieve the satisfied CDT efficacy is still a big challenge. In this paper, the supramolecular nanovalves (SNs) with oxidative amplification agents cinnamaldehyde-(phenylboronic acid pinacol ester) conjugates (CA-BE) encapsulated inside were developed to accelerate and amplify the generation of ·OH and consumption of GSH while augmenting the CDT efficacy. SNs were obtained through ferrocene/Au modified mesoporous silica nanoparticles (MSN@Au-Fc) and active targeting β-cyclodextrin modified hyaluromic acid (HA-CD). After CD44 receptor-mediated cellular internalization, the CA-BE were released to elevate H₂O₂ amount and consume GSH for the desired generation of higher cytotoxic hydroxyl radicals (·OH). Moreover, the NIR-activated MSN@Au-Fc can increase the temperature for the accelerated and amplified oxidative stress. As such, the therapeutic efficacy of our synthesized CA-BE and the accompanied hyperthermia were augmented toward synergistically inhibiting tumor growth.

Tumor-targeted glycogen nanoparticles loaded with hemin and glucose oxidase to promote tumor synergistic therapy

Strategies which are used to address the low levels of intracellular hydrogen peroxide and the development of biocompatible catalysts still need to be fulfilled in tumor chemodynamic therapy. Therefore, a novel tumor-targeted glycogen-based nanoparticle system (GN/He/GOx/HA) was developed to co-deliver hemin (He) and GOx, which can self-supply glucose formed upon degradation of glycogen by α-glycosidase in the lysosome environment, in order to achieve synergistic antitumor therapy. Hyaluronic acid (HA) was selected as the outer shell to protect the activity of GOx, and to increase the uptake by tumor cells via CD44 receptor-mediated endocytosis. GN/He/GOx/HA NPs had a good stability in the blood circulation, but fast release of the therapeutic cargos upon intracellular uptake. Hemin had a cascade catalytic reaction with GOx. Furthermore, GN/He/GOx/HA NPs had the strongest cytotoxicity in Hela cells in a glucose concentration dependent manner. The NPs could efficiently produce reactive oxygen species in tumor cells, resulting in a decrease in the mitochondrial membrane potential and apoptosis of tumor cells. The in vivo results showed that the drug-loaded nanoparticles had good safety, biocompatibility, and efficacious antitumor effect. Therefore, the glycogen-based nanoparticle delivery system provides potential application for self-enhancing CDT, which can be used for effective antitumor therapy.

Two-Dimensional Fe-N-C Single-Atomic-Site Catalysts with Boosted Peroxidase-Like Activity for a Sensitive Immunoassay

Single-atomic-site catalysts (SASCs) with peroxidase (POD)-like activities have been widely used in various sensing platforms, like the enzyme-linked immunosorbent assay (ELISA). Herein, a two-dimensional Fe-N-C-based SASC (2D Fe-SASC) is successfully synthesized with excellent POD-like activity (specific activity = 90.11 U/mg) and is used to design the ELISA for herbicide detection. The 2D structure of Fe-SASC enables the exposure of numerous single atomic active sites on the surface as well as boosts the POD-like activity, thereby enhancing the sensing performance. 2D Fe-SASC is assembled into competitive ELISA kit, which achieves an excellent detection performance for 2,4-dichlorophenoxyacetic acid (2,4-D). Fe-SASC has great potential in replacing high-cost natural enzymes and working on various advanced sensing platforms with high sensitivity for the detection of various target biomarkers.

Biodegradable MnO2-based gene-engineered nanocomposites for chemodynamic therapy and enhanced antitumor immunity

Immune checkpoint blockade (ICB) is emerging as a promising therapeutic approach for clinical treatment against various cancers. However, ICB based monotherapies still suffer from low immune response rate due to the limited and exhausted tumor-infiltrating lymphocytes as well as tumor immunosuppressive microenvironment. In this work, the cell membrane with surface displaying PD-1 proteins (PD1-CM) was prepared for immune checkpoint blockade, which was further combined with multifunctional and biodegradable MnO2 for systematic and robust antitumor therapy. The MnO2-based gene-engineered nanocomposites can catalyze the decomposition of abundant H2O2 in TME to generate O2, which can promote the intratumoral infiltration of T cells, and thus improve the effect of immune checkpoint blockade by PD-1 proteins on PD1-CM. Furthermore, MnO2 in the nanocomposites can be completely degraded into Mn2+, which can catalyze the generation of highly toxic hydroxyl radicals for chemodynamic therapy, thereby further enhancing the therapeutic effect. In addition, the prepared nanocomposites possess the advantages of low cost, easy preparation and good biocompatibility, which are expected to become promising agents for combination immunotherapy.

A Cascade Nanoreactor of Metal-Protein-Polyphenol Capsule for Oxygen-Mediated Synergistic Tumor Starvation and Chemodynamic Therapy

Starvation therapy kills tumor cells via consuming glucose to cut off their energy supply. However, since glucose oxidase (GOx)-mediated glycolysis is oxygen-dependent, the cascade reaction based on GOx faces the challenge of a hypoxic tumor microenvironment. By decomposition of glycolysis production of H₂ O₂ into O₂ , starvation therapy can be enhanced, but chemodynamic therapy is limited. Here, a close-loop strategy for on demand H₂ O₂ and O₂ delivery, release, and recycling is proposed. The nanoreactor (metal-protein-polyphenol capsule) is designed by incorporating two native proteins, GOx and hemoglobin (Hb), in polyphenol networks with zeolitic imidazolate framework as sacrificial templates. Glycolysis occurs in the presence of GOx with O₂ consumption and the produced H₂ O₂ reacts with Hb to produce highly cytotoxic hydroxyl radicals (•OH) and methemoglobin (MHb) (Fenton reaction). Benefiting from the different oxygen carrying capacities of Hb and MHb, oxygen on Hb is rapidly released to supplement its consumption during glycolysis. Glycolysis and Fenton reactions are mutually reinforced by oxygen supply, consuming more glucose and producing more hydroxyl radicals and ultimately enhancing both starvation therapy and chemodynamic therapy. This cascade nanoreactor exhibits high efficiency for tumor suppression and provides an effective strategy for oxygen-mediated synergistic starvation therapy and chemodynamic therapy.

Role and Application of Biocatalysts in Cancer Drug Discovery

A biocatalyst is an enzyme that speeds up or slows down the rate at which a chemical reaction occurs and speeds up certain processes by 108 times. It is used as an anticancer agent because it targets drug activation inside the tumor microenvironment while limiting damage to healthy cells. Biocatalysts have been used for the synthesis of different heterocyclic compounds and is also used in the nano drug delivery systems. The use of nano-biocatalysts for tumor-targeted delivery not only aids in tumor invasion, angiogenesis, and mutagenesis, but also provides information on the expression and activity of many markers related to the microenvironment. Iosmapinol, moclobemide, cinepazide, lysine dioxygenase, epothilone, 1-homophenylalanine, and many more are only some of the anticancer medicines that have been synthesised using biocatalysts. In this review, we have highlighted the application of biocatalysts in cancer therapies as well as the use of biocatalysts in the synthesis of drugs and drug-delivery systems in the tumor microenvironment.

In situ-transition nanozyme triggered by tumor microenvironment boosts synergistic cancer radio-/chemotherapy through disrupting redox homeostasis

Disrupting redox homeostasis in the tumor microenvironment (TME), like excessive H2O2, glutathione (GSH) and weak acidity, has been proved as an effective tumor therapeutic strategy. Herein, we constructed a TME-responsive nanozyme, DOX@HMSN/Mn3O4(R), with reversible Mn3+/Mn2+ transition in situ triggered by TME to perturb the intrinsic redox homeostasis and catalyze reactive oxygen species (ROS) overproduction. In addition, this nanozyme could react with excess GSH in TME to produce GSSG, resulting in the consumption of reducing agents to suppress ROS clearance. Density functional theory calculations further confirmed that the nanozyme mainly exhibited the oxidase-like activity to catalyze the formation of hydroxyl radicals from O2, thus strengthening the oxidation environment in the TME. Combined with radiotherapy, the high-energy X-ray could excite the outer-layer electrons in the nanozyme, forming photoelectrons that participate in the oxidase-like enzymatic reaction, thus intensifying ROS accumulation and amplifying the radio-/chemotherapeutic efficacy.

Immunogenic Cell Death Activates the Tumor Immune Microenvironment to Boost the Immunotherapy Efficiency

Tumor immunotherapy is only effective in a fraction of patients due to a low response rate and severe side effects, and these challenges of immunotherapy in clinics can be addressed through induction of immunogenic cell death (ICD). ICD is elicited from many antitumor therapies to release danger associated molecular patterns (DAMPs) and tumor-associated antigens to facilitate maturation of dendritic cells (DCs) and infiltration of cytotoxic T lymphocytes (CTLs). The process can reverse the tumor immunosuppressive microenvironment to improve the sensitivity of immunotherapy. Nanostructure-based drug delivery systems (NDDSs) are explored to induce ICD by incorporating therapeutic molecules for chemotherapy, photosensitizers (PSs) for photodynamic therapy (PDT), photothermal conversion agents for photothermal therapy (PTT), and radiosensitizers for radiotherapy (RT). These NDDSs can release loaded agents at a right dose in the right place at the right time, resulting in greater effectiveness and lower toxicity. Immunotherapeutic agents can also be combined with these NDDSs to achieve the synergic antitumor effect in a multi-modality therapeutic approach. In this review, NDDSs are harnessed to load multiple agents to induce ICD by chemotherapy, PDT, PTT, and RT in combination of immunotherapy to promote the therapeutic effect and reduce side effects associated with cancer treatment.

Liposomal Glucose Oxidase for Enhanced Photothermal Therapy and Photodynamic Therapy against Breast Tumors

Organic near-infrared fluorescent dye mediated photothermal therapy (PTT) and photodynamic therapy (PDT) suffer from heat shock response, since, heat shock proteins (HSPs) are overexpressed and can repair the proteins damaged by PTT and PDT. Starvation therapy by glucose oxide (GOx) can inhibit the heat shock response by limiting the energy supply. However, the delivery of sufficient and active GOx remains a challenge. To solve this problem, we utilize liposomes as drug carriers and prepare GOx loaded liposome (GOx@Lipo) with a high drug loading content (12.0%) and high enzymatic activity. The successful delivery of GOx shows excellent inhibition of HSPs and enhances PTT and PDT. Additionally, we apply the same liposome formulation to load near-infrared dye 1,1'-dioctadecyl-3,3,3',3'-tetramethylindotricarbo cyanine iodide (DiR) and prepare DiR contained liposomes (DiR@Lipo) for PTT and PDT. The liposomal formulation substantially enhances the PTT and PDT properties of DiR as well as the cellular uptake and tumor accumulation. Finally, the combination therapy shows excellent tumor inhibition on 4T1 tumor-bearing mice. Interestingly, we also find that the starvation therapy can efficiently inhibit tumor metastasis, which is probably due to the immunogenic effect. Our work presents a biocompatible and effective carrier for the combination of starvation therapy and phototherapy, emphasizing the importance of auxiliary starvation therapy against tumor metastasis and offering important guidance for clinical PTT and PDT.

Redox dyshomeostasis strategy for tumor therapy based on nanomaterials chemistry

Redox homeostasis, as an innate cellular defense mechanism, not only contributes to malignant transformation and metastasis of tumors, but also seriously restricts reactive oxygen species (ROS)-mediated tumor therapies, such as chemotherapy, radiotherapy, photodynamic therapy (PDT), and chemodynamic therapy (CDT). Therefore, the development of the redox dyshomeostasis (RDH) strategy based on nanomaterials chemistry is of great significance for developing highly efficient tumor therapy. This review will firstly introduce the basic definition and function of cellular redox homeostasis and RDH. Subsequently, the current representative progress of the nanomaterial-based RDH strategy for tumor therapy is evaluated, summarized and discussed. This strategy can be categorized into three groups: (1) regulation of oxidizing species; (2) regulation of reducing species and (3) regulation of both of them. Furthermore, the current limitations and potential future directions for this field will be briefly discussed. We expect that this review could attract positive attention in the chemistry, materials science, and biomedicine fields and further promote their interdisciplinary integration.

This review summarizes the current progress of the redox dyshomeostasis (RDH) strategy for tumor therapy. This strategy makes tumor cells more sensitive to current therapy patterns through using nanomaterials to disrupt redox homeostasis.

In Situ Sprayed Starvation/Chemodynamic Therapeutic Gel for Post-Surgical Treatment of IDH1 (R132H) Glioma

Complete resection of isocitrate dehydrogenase 1 (IDH1) (R132H) glioma is unfeasible and the classic post-surgical chemo/radiotherapy suffers from high recurrence and low survival rate. IDH1 (R132H) cells are sensitive to low concentrations of glucose and high concentrations of reactive oxygen species (ROS) due to inherent metabolism reprograming. Hence, a starvation/chemodynamic therapeutic gel is developed to combat residual IDH1 (R132H) tumor cells after surgery. Briefly, glucose oxidase (GOx) is mineralized with manganese-doped calcium phosphate to form GOx@MnCaP nanoparticles, which are encapsulated into the fibrin gel (GOx@MnCaP@fibrin). After spraying gel in the surgical cavity, GOx catalyzes the oxidation of glucose in residual IDH1 (R132H) cells and produces H₂ O₂ . The generated H₂ O₂ is further converted into highly lethal hydroxyl radicals (•OH) by a Mn²⁺ -mediated Fenton-like reaction to further kill the residual IDH1 (R132H) cells. The as-prepared starvation/chemodynamic therapeutic gel shows much higher therapeutic efficacy toward IDH1 (R132H) cells than IDH1 (WT) cells, and achieves long-term survival.

Nanozyme-Based Enhanced Cancer Immunotherapy

Catalytic nanoparticles with natural enzyme-mimicking properties, known as nanozymes, have emerged as excellent candidate materials for cancer immunotherapy. Owing to their enzymatic activities, artificial nanozymes not only serve as responsive carriers to load drugs and therapeutic molecules for cancer treatment, but also act as enzymes for modulating the immunosuppression of the tumor microenvironment (TME) via the catalytic activities of catalase, peroxidase, superoxide dismutase, and oxidase. The immunosuppressive pro-tumor TME can be reversed to the immunoactive anti-tumor TME by utilizing both reactive oxygen species (ROS)-generating and ROS-scavenging nanozymes, which enhance the efficacy of cancer immunotherapy. In this review, we introduce representative ROS-generating and ROS-scavenging nanozymes and discuss how artificial nanozymes respond to the conditions of the TME. Based on the mutual interaction between nanozymes and TME, recent therapeutic pathways to provoke anti-cancer immune responses using nanozymes are discussed.

Glutathione-Responsive Chemodynamic Therapy of Manganese(III/IV) Cluster Nanoparticles Enhanced by Electrochemical Stimulation via Oxidative Stress Pathway

Escalating the level of reactive oxygen species (ROS) in a tumor microenvironment is one of the effective strategies to improve the efficacy of anticancer therapy. In this work, manganese cluster nanoparticles (Mn12) encapsulated with heparin (Mn12-heparin) were developed as a chemodynamic therapeutic agent for cancer treatment by raising ROS levels in tumor cells via cascade reactions. The manganese cluster is a cluster of mixed valence (III/IV) with acetate as the ligand. The cluster is readily subject to reduction by glutathione (GSH) to release Mn(II), which reacts with H2O2 to generate hydroxyl radicals via a Fenton-like pathway. The generation of hydroxyl radicals could be enhanced by the stimulation of an external alternative electric field during which GSH acts as an electron mediator to enhance the release of Mn(II) from the cluster. The relatively high levels of both H2O2 and GSH and the acidic environment in tumor cells strengthen its specificity when the manganese cluster system is employed to suppress or eliminate tumors. Both in vitro and in vivo results suggest that, in addition to the cytotoxicity imposed by the raised ROS level due to the presence of Mn(II) species, the depletion of endogenous GSH leads indirectly to the inhibition of glutathione peroxidase 4 (GPX4), consequently raising the lipid peroxidation (LPO) level to cause ferroptosis. The apoptosis and ferroptosis jointly render the manganese-based agent potent efficacy with tumor-targeting specificity in antitumor treatment under electric stimulation.

Biomimetic Nanomaterials Triggered Ferroptosis for Cancer Theranostics

Ferroptosis, as a recently discovered non-apoptotic programmed cell death with an iron-dependent form, has attracted great attention in the field of cancer nanomedicine. However, many ferroptosis-related nano-inducers encountered unexpected limitations such as immune exposure, low circulation time, and ineffective tumor targeting. Biomimetic nanomaterials possess some unique physicochemical properties which can achieve immune escape and effective tumor targeting. Especially, certain components of biomimetic nanomaterials can further enhance ferroptosis. Therefore, this review will provide a comprehensive overview on recent developments of biomimetic nanomaterials in ferroptosis-related cancer nanomedicine. First, the definition and character of ferroptosis and its current applications associated with chemotherapy, radiotherapy, and immunotherapy for enhancing cancer theranostics were briefly discussed. Subsequently, the advantages and limitations of some representative biomimetic nanomedicines, including biomembranes, proteins, amino acids, polyunsaturated fatty acids, and biomineralization-based ferroptosis nano-inducers, were further spotlighted. This review would therefore help the spectrum of advanced and novice researchers who are interested in this area to quickly zoom in the essential information and glean some provoking ideas to advance this subfield in cancer nanomedicine.

One-Pot Synthesis of Multifunctional Carbon-Based Nanoparticle-Supported Dispersed Cu2+ Disrupts Redox Homeostasis to Enhance CDT

In chemodynamic therapy (CDT), the levels of reactive oxygen species (ROS) production plays an important role for evaluating the therapeutic efficacy. However, the high levels of glutathione (GSH) in tumor cells consume the ROS, directly reducing the therapeutic efficiency. Herein, we synthesized carbon-based nanoparticle (Cu-cys CBNPs) using one-pot strategy, which consume GSH via redox reactions to produce Cu⁺ that catalyze H₂ O₂ to produce ^. OH, thus the ROS level was observably increased through this synergistic effect. In vivo experiments further revealed that Cu-cys CBNPs could effectively inhibit tumor growth. Additionally, Cu-cys CBNPs can affect the activity of some protein sulfhydryl groups in cells, which was assessed by rdTOP-ABPP assay. In general, this study not only provides a potential CDT drug, but also provides a strategy for one-pot synthesis of multifunctional nanomaterials.

Immunotherapy of tumors by tailored nano-zeolitic imidazolate framework protected biopharmaceuticals

In cancer immunotherapy, antibodies have acquired rapidly increasing attention due to their sustained immune effect by target specific delivery without any adverse effects. Among many recent strategies, controlled delivery of monoclonal antibodies, check point inhibitor storage and tumor-specific targeted delivery have enabled biodegradable immunotherapeutic delivery via translation of tailored nano-zeolitic imidazolate frameworks (ZIFs) with encapsulated biopharmaceuticals. In addition, a robust antitumor immunity was developed by anti-programmed death ligand-1 (anti-PD-L1) antibody delivery by ZIF-8 with polyethylene glycol (PEG) protection by forming a multiple immunoregulatory system. The unique biorecognition capability of antibodies, encapsulated in ZIFs, was recognized by using growth on different substrates, such as bioconjugates on gold nanorods, to transform them into plasmonic nanobiosensors with sensitivity of the refractive index profile of surface plasmons to track the conjugating antibody. Herein, we have discussed the mechanistic window of antibody delivery-based immunotherapy via the encapsulation of antibodies within ZIFs as an emerging tool for protecting biopharmaceuticals from the complex cellular microenvironment and hyperthermia to enable an antitumor immune response. To fully achieve the potential of antibodies upon ZIF encapsulation, more endeavors should be undertaken in the biodegradable engineering of ZIF-surfaces via forming cellular or polymeric layers to gain higher in vivo circulation time without inhibiting endocytosis by tumor cells. The possible future prognosis for achieving ZIF-protected biocompatible and biodegradable immunotherapeutic antibody delivery systems of therapeutic significance is discussed.

A Ferrocene-Functionalized Covalent Organic Framework for Enhancing Chemodynamic Therapy via Redox Dyshomeostasis

Chemodynamic therapy (CDT), which induces cell death by decomposing high levels of H₂ O₂ in tumor cells into highly toxic ·OH, is recognized as a promising antineoplastic approach. However, current CDT approaches are often restricted by the highly controlled and upregulated cellular antioxidant defense. To enhance ·OH-induced cellular damage by CDT, a covalent organic framework (COF)-based, ferrocene (Fc)- and glutathione peroxidase 4 (GPX4) inhibitor-loaded nanodrug, RSL3@COF-Fc (2b), is fabricated. The obtained 2b not only promotes in situ Fenton-like reactions to trigger ·OH production in cells, but also attenuates the repair mechanisms under oxidative stress via irreversible covalent GPX4 inhibition. As a result, these two approaches synergistically result in massive lipid peroxide accumulation, subsequent cell damage, and ultimately ferroptosis, while not being limited by intracellular glutathione. It is believed that this research provides a paradigm for enhancing reactive oxygen species-mediated oncotherapy through redox dyshomeostasis and may provide new insights for developing COF-based nanomedicine.

Mimicking natural strategies to create multi-environment enzymatic reactors: From natural cell compartments to artificial polyelectrolyte reactors

Engineering microenvironments for sequential enzymatic reactions has attracted specific interest within different fields of research as an effective strategy to improve the catalytic performance of enzymes. While in industry most enzymatic reactions occur in a single compartment carrier, living cells are however able to conduct multiple reactions simultaneously within confined sub-compartments, or organelles. Engineering multi-compartments with regulated environments and transformation properties enhances enzyme activity and stability and thus increases the overall yield of final products. In this review, we discuss current and potential methods to fabricate artificial cells for sequential enzymatic reactions, which are inspired by mechanisms and metabolic pathways developed by living cells. We aim to advance the understanding of living cell complexity and its compartmentalization and present solutions to mimic these processes in vitro. Particular attention has been given to layer-by-layer assembly of polyelectrolytes for developing multi-compartments. We hope this review paves the way for the next steps toward engineering of smart artificial multi-compartments with adoptive stimuli-responsive properties, mimicking living cells to improve catalytic properties and efficiency of the enzymes and enhance their stability.

Application of Nano-Drug Delivery System Based on Cascade Technology in Cancer Treatment

In the current cancer treatment, various combination therapies have been widely used, such as photodynamic therapy (PDT) combined with chemokinetic therapy (CDT). However, due to the complexity of the tumor microenvironment (TME) and the limitations of treatment, the efficacy of current treatment options for some cancers is unsatisfactory. Nowadays, cascade technology has been used in cancer treatment and achieved good therapeutic effect. Cascade technology based on nanotechnology can trigger cascade reactions under specific tumor conditions to achieve precise positioning and controlled release, or amplify the efficacy of each drug to improve anticancer efficacy and reduce side effects. Compared with the traditional treatment, the application of cascade technology has achieved the controllability, specificity, and effectiveness of cancer treatment. This paper reviews the application of cascade technology in drug delivery, targeting, and release via nano-drug delivery systems in recent years, and introduces their application in reactive oxygen species (ROS)-induced cancer treatment. Finally, we briefly describe the current challenges and prospects of cascade technology in cancer treatment in the future.

In Situ Fluorogenic Reaction Generated via Ascorbic Acid for the Construction of Universal Sensing Platform

A highly fluorescent emission reaction between terephthalic acid (PTA) and ascorbic acid (AA) via simple control of the reaction temperature was first revealed with the detailed formation mechanism and various characterizations including electron paramagnetic resonance and mass spectrometry. Based on the AA-responsive emission, the alkaline phosphatase (ALP) triggered the transformation of l-ascorbic acid 2-phosphate trisodium salt to AA was integrated with the present system for developing a sensitive, selective, and universal platform. The monitoring of the activity of ALP and the fabrication of ALP-based enzyme-linked immunoassay (ELISA) with carcinoembryonic antigen (CEA) as the model target was performed. The fluorescence intensity correlated well to the CEA concentration in the ranges of 0.25-30 ng/mL, with a detection limit of 0.08 ng/mL. Such a facile protocol based on the fluorescent reaction between PTA and AA without the assistance of catalysis of nanomaterials avoided the laborious synthesis procedure and provided a direct strategy for the early clinical diagnosis coupled with ALP-related catalysis.