Mitochondrial Dysfunction and Antioxidation Dyshomeostasis-Enhanced Tumor Starvation Synergistic Chemotherapy Achieved using a Metal-Organic Framework-Based Nano-Enzyme Reactor

Emerging glucose oxidase-delivering nanomedicines for enhanced tumor therapy

Abnormalities in glucose metabolism have been shown to characterize malignant tumors. Glucose depletion by glucose oxidase (GOD) has shown great potential in tumor therapy by causing tumor starvation. Since 2017, nanomedicines have been designed and utilized to deliver GOD for more precise and effective glucose modulation, which can overcome intrinsic limitations of different cancer therapeutic modalities by remodeling the tumor microenvironment to enhance antitumor therapy. To date, the topic of GOD-delivering nanomedicines for enhancing tumor therapy has not been comprehensively summarized. Herein, this review aims to provide an overview and discuss in detail recent advances in GOD delivery and directly involved starvation therapy strategies, GOD-sensitized various tumor therapy strategies, and GOD-mediated multimodal antitumor strategies. Finally, the challenges and outlooks for the future progress of the emerging tumor therapeutic nanomedicines are discussed. This review provides intuitive and specific insights to a broad audience in the fields of nanomedicines, biomaterials, and cancer therapy.

A dual-mode nanoplatform based on Cu2O@Au-Pt nanoenzyme and CHA-HCR DNA framework circuit for sensitive detection of CD122 and CD17

A Cu2O@Au-Pt nanoenzyme is prepared and integrated with a DNA nanocircuit to construct an electrochemical/colorimetric dual-mode sensing platform for the sensitive detection of CD122 and CD17, which are biomarkers for immune-related diseases.When CD122 is present, it triggers a catalyzed hairpin assembly (CHA) reaction, forming a double-stranded structure recognized by the DNA framework's "arms" (C-DNA), with methylene blue (MB) adsorbing onto it as an electron receptor. Methylene blue (MB) is adsorbed onto the double-stranded structure and introduced as a cathodic electron receptor. In the presence of the target CD17, it acts as a bridging molecule to engage in a hybridization chain reaction (HCR), producing HCR products that are specifically recognized by the other set of "arms" within the C-DNA, which captures abundant MB and generates a heightened response signal. MB can be electrochemically reduced to its reduced state to cause a change in solution color and an increase in RGB Blue values. This method offers a detection range of 0.0001-10,000 pM, with detection limits for CD122 and CD17 of 23.9 and 36.0 aM (S/N = 3) using the electrochemical method, and 26.2 and 26.6 aM (S/N = 3) in the colorimetric mode, respectively. This study presents a novel, reliable multi-target detection strategy for disease biomarkers.

Optimizing cancer therapy through metal organic frameworks-based nanozymes

Cancer remains a leading global health challenge, with conventional treatments facing limitations due to drug resistance and adverse effects arising from tumor heterogeneity. Nanozymes, nanomaterials mimicking natural enzymes, have emerged as promising therapeutic agents owing to their catalytic efficiency, stability, and biocompatibility. Among nanozymes, MOFs-based nanozymes are particularly attractive due to the inherent tunability of MOFs, which allows for precise control over their structure, porosity, and catalytic activity. This review comprehensively explores the recent advancements in optimizing cancer therapy through MOFs-based nanozymes. We delve into the classification of these nanozymes based on their enzyme-mimicking activities, including peroxidase, oxidase, catalase, and superoxide dismutase, and discuss their underlying catalytic mechanisms. Additionally, emerging single-atom nanozymes are discussed as a distinct category. Furthermore, we highlight the diverse therapeutic strategies employing MOFs-based nanozymes, such as starvation therapy, oxygen supply, catalytic therapy, glutathione depletion, and activation of therapeutic agents within tumor microenvironment. By exploiting the unique properties of MOFs, these nanozymes demonstrate enhanced therapeutic efficacy in various cancer treatment modalities, including chemotherapy, radiotherapy, photodynamic therapy, and sonodynamic therapy. This review underscores the significant potential of MOFs-based nanozymes as a versatile platform for developing next-generation cancer therapeutics, offering improved targeting, reduced systemic toxicity, and enhanced treatment outcomes.

Cascade specific endogenous Fe3+ interference and in situ catalysis for tumor therapy with stemness suppression

Cancer stem-like cells (CSCs), featuring high tumorigenicity and invasiveness, are one of the critical factors leading to the failure of clinical cancer treatment such as metastasis and recurrence. However, current strategies suffer from the low stemness-inhibiting efficacy on CSCs by conventional molecular agents and the poor lethal effects against bulk tumor cells. Here we engineer a coordination nanomedicine by 2,5-dihydroxyterephthalic acid (DHT) complexing zinc ions (Zn2+) as a double-effect nanodisrupter of tumor iron (Fe) and redox homeostasis for catalysis-boosted tumor therapy with stemness inhibition. Taking advantage of the much higher binding force of DHT toward Fe3+, this nanomedicine can specifically chelate endogenous Fe3+ into its nanostructure and release Zn2+, and the in situ formed hexacoordinated Fe-DHT conformation is of much enhanced reducibility in order to promote reactive oxygen species (ROS) production in tumors. The nanomedicine-mediated Fe depletion and ROS generation collectively induce CSC differentiation via downregulating the Wnt signaling and inducing forkhead box O3 (FoxO3) activation, respectively. Notably, the combined tumor-selective ROS generation and Zn2+-induced antioxidation dysfunction potently trigger intratumoral oxidative damage leading to both cellular apoptosis and ferroptosis. This nanomedicine, capable of synchronously treating CSCs and bulk tumor cells, has been demonstrated to effectively inhibit the growth, postoperative recurrence and metastasis of orthotopic triple-negative breast tumors in vivo, offering an encouraging candidate of cancer therapeutic agents for treating CSCs-enriched malignancy.

Focused starvation of tumor cells using glucose oxidase: A comprehensive review

Starvation therapy targets the high metabolic demand of tumor cells. It primarily leans over the consumption of intracellular glucose and simultaneous blockade of alternative metabolic pathways. The strategy involves the use of glucose oxidase (GOx) for catalyzing the conversion of glucose into gluconic acid and hydrogen peroxide. Under these conditions, metabolic re-programming of tumor cells enables the utilization of substrates such as amino acids, fatty acids and lipids. This can be overcome by co-administration of chemo-, photo- and immuno-therapeutics together with glucose oxidase. Targeted delivery of glucose oxidase at tumor site can be enabled with the use of nanoformulations. In this review, we highlight that the outcomes of starvation therapy can be improved using rationally developed nano-formulations. It is possible to load synergistically acting bioactives in these formulations and deliver in site-specific manner and hence achieve the elimination of tumors cells with greater efficacy.

Imprinted membrane-covalent organic framework platform for efficient label-free visual detection of Listeria monocytogenes and Salmonella typhimurium in food samples

BACKGROUND

Rapid and sensitive detection of foodborne pathogens in food plays a crucial role in controlling outbreaks of foodborne diseases, of which Listeria monocytogenes and Salmonella typhimurium are representative and notable pathogens. Thus, it's of great importance to achieve the effective detection of these pathogens. However, the most common detection methods (culture-based technique, Polymerase Chain Reaction and immunological methods) have disadvantages that cannot be ignored, such as time-consuming, laborious, complex sample preparation process, and the possibility of cross-reaction. Hence, it is essential to develop a facile detection method for the pathogens with high sensitivity and specificity to avoid the above-mentioned disadvantages.

RESULTS

We report a label-free visual platform for the simultaneous capture and detection of Listeria monocytogenes and Salmonella typhimurium. For the first time, we have prepared polydimethylsiloxane-Chromotrope 2R membrane which serves as the substrate for bacterial capture and enrichment through the formation of specific recognition sites. The positively charged Pt-covalent organic framework combines with the pathogens through surface charge interaction, thereby the label-free sandwich platform is formed. Remarkable peroxidase activity of Pt-covalent organic framework converts the conversion of bacterial quantity into amplified color signal by catalyzing 3,3',5,5'-Tetramethylbenzidine to oxidized 3,3',5,5'-Tetramethylbenzidine. The platform demonstrates the capability to identify two representative food-borne pathogens within a time frame of 100 min, exhibiting high sensitivity and excellent specificity without the interference from non-target bacteria. The limit of detection of the visual platform toward Listeria monocytogenes and Salmonella typhimurium was 1.61 CFU mL-1 and 1.31 CFU mL-1, respectively. And the limit of quantification toward Listeria monocytogenes and Salmonella typhimurium was 4.94 CFU mL-1 and 2.47 CFU mL-1, respectively. The relative standard derivations of the visual platform for both bacteria were lower than 4.9 %. Furthermore, our proposed platform has obtained reliable and satisfactory results on analyzing diverse food samples.

SIGNIFICANCE

This research expands the application of a label-free platform combined with unlabeled nanocomponents in the rapid isolation and detection of diverse of food-borne pathogens. The platform possesses the advantages of simple operation and real-time monitoring, without complicated sample pretreatment process. The whole detection process can realize the simultaneous monitoring of Listeria monocytogenes and Salmonella typhimurium within 100 min. Furthermore, it is also of reference significance for the detection of other common pathogens.

Intertumoral and intratumoral barriers as approaches for drug delivery and theranostics to solid tumors using stimuli-responsive materials

The solid tumors provide a series of biological barriers in cellular microenvironment for designing drug delivery methods based on advanced stimuli-responsive materials. These intertumoral and intratumoral barriers consist of perforated endotheliums, tumor cell crowding, vascularity, lymphatic drainage blocking effect, extracellular matrix (ECM) proteins, hypoxia, and acidosis. Triggering opportunities have been drawn for solid tumor therapies based on single and dual stimuli-responsive drug delivery systems (DDSs) that not only improved drug targeting in deeper sites of the tumor microenvironments, but also facilitated the antitumor drug release efficiency. Single and dual stimuli-responsive materials which are known for their lowest side effects can be categorized in 17 main groups which involve to internal and external stimuli anticancer drug carriers in proportion to microenvironments of targeted solid tumors. Development of such drug carriers can circumvent barriers in clinical trial studies based on their superior capabilities in penetrating into more inaccessible sites of the tumor tissues. In recent designs, key characteristics of these DDSs such as fast response to intracellular and extracellular factors, effective cytotoxicity with minimum side effect, efficient permeability, and rate and location of drug release have been discussed as core concerns of designing paradigms of these materials.

Advances in H2O2-supplying materials for tumor therapy: synthesis, classification, mechanisms, and applications

Hydrogen peroxide (H2O2) as a reactive oxygen species produced by cellular metabolism can be used in antitumor therapy. However, the concentration of intracellular H2O2 limits its application. Some materials could enhance the concentration of intracellular H2O2 to strengthen antitumor therapy. In this review, the recent advances in H2O2-supplying materials in terms of promoting intracellular H2O2 production and exogenous H2O2 supply are summarized. Then the mechanism of H2O2-supplying materials for tumor therapy is discussed from three aspects: reconstruction of the tumor hypoxia microenvironment, enhancement of oxidative stress, and the intrinsic anti-tumor ability of H2O2-supplying materials. In addition, the application of H2O2-supplying materials for tumor therapy is discussed. Finally, the future of H2O2-supplying materials is presented. This review aims to provide a novel idea for the application of H2O2-supplying materials in tumor therapy.

A dual responsive nitric oxide / β-lapachone co-delivery platform for redox imbalance-enhanced tumor therapy

Nitric oxide (NO) / β-Lapachone (Lap) combined therapy by causing oxidative stress is an effective tumor therapy strategy. Herein, a dual-responsive lipid nanoparticles (LNPs) LSNO for NO / Lap co-delivery were constructed from the zinc-coordinated lipid (DSNO(Zn)) and the hydrophobic drug Lap in the presence of helper lipids (DOPE and DSPE-PEG2000). The zinc-coordinated structure in LSNO might elevate the Zn2+ content in tumor cells, contributing to antioxidant imbalance. The fluorescent assays proved the light-triggered NO release and fluorescent self-reporting abilities of LSNO. In addition, the LNPs had good drug release behavior under high concentration of GSH, indicating the NO / drug co-delivery capacity. In vitro antitumor assays showed that the NO / Lap combination treatment group could induce more significant tumor cell growth inhibition and cell apoptosis than individual NO or Lap treatment. The following mechanism studies revealed that NO / Lap combination treatment led to distinct oxidative stress by producing reactive oxygen species (ROS) and peroxynitrite anion (ONOO-). On the other hand, the intracellular redox balance could be further disrupted by Lap-induced NADPH consumption and Zn2+ / NO-induced reductase activities downregulation, thus promoting the degree of cell damage. Besides, it was also found that NO and Lap could directly damage nuclear DNA and induce mitochondrial dysfunction, thereby leading to caspase-3 activation and tumor cell death. These results proved that LSNO could serve as a promising multifunctional tumor therapy platform.

Metal-Organic Framework Nanomaterials as a Medicine for Catalytic Tumor Therapy: Recent Advances

Nanomaterials, with unique physical, chemical, and biocompatible properties, have attracted significant attention as an emerging active platform in cancer diagnosis and treatment. Amongst them, metal-organic framework (MOF) nanostructures are particularly promising as a nanomedicine due to their exceptional surface functionalities, adsorption properties, and organo-inorganic hybrid characteristics. Furthermore, when bioactive substances are integrated into the structure of MOFs, these materials can be used as anti-tumor agents with superior performance compared to traditional nanomaterials. In this review, we highlight the most recent advances in MOFs-based materials for tumor therapy, including their application in cancer treatment and the underlying mechanisms.

Mg-ZIF nanozyme regulates the switch between osteogenic and lipogenic differentiation in BMSCs via lipid metabolism

The accumulation of reactive oxygen species (ROS) within the bone marrow microenvironment leads to diminished osteogenic differentiation and heightened lipogenic differentiation of mesenchymal stem cells residing in the bone marrow, ultimately playing a role in the development of osteoporosis (OP). Mitigating ROS levels is a promising approach to counteracting OP. In this study, a nanozyme composed of magnesium-based zeolitic imidazolate frameworks (Mg-ZIF) was engineered to effectively scavenge ROS and alleviate OP. The results of this study indicate that Mg-ZIF exhibits significant potential in scavenging ROS and effectively promoting osteogenic differentiation of bone mesenchymal stem cells (BMSCs). Additionally, Mg-ZIF was found to inhibit the differentiation of BMSCs into adipose cells. In vivo experiments further confirmed the ability of Mg-ZIF to mitigate OP by reducing ROS levels. Mechanistically, Mg-ZIF enhances the differentiation of BMSCs into osteoblasts by upregulating lipid metabolic pathways through ROS scavenging. The results indicate that Mg-ZIF has potential as an effective therapeutic approach for the treatment of osteoporosis.

Nanoenabled Intracellular Metal Ion Homeostasis Regulation for Tumor Therapy

Endogenous essential metal ions play an important role in many life processes, especially in tumor development and immune response. The approval of various metallodrugs for tumor therapy brings more attention to the antitumor effect of metal ions. With the deepening understanding of the regulation mechanisms of metal ion homeostasis in vivo, breaking intracellular metal ion homeostasis becomes a new means to inhibit the proliferation of tumor cells and activate antitumor immune response. Diverse nanomedicines with the loading of small molecular ion regulators or metal ions have been developed to disrupt metal ion homeostasis in tumor cells, with higher safety and efficiency than free small molecular ion regulators or metal compounds. This comprehensive review focuses on the latest progress of various intracellular metal ion homeostasis regulation-based nanomedicines in tumor therapy including calcium ion (Ca2+ ), ferrous ion (Fe2+ ), cuprous ion (Cu+ ), managanese ion (Mn2+ ), and zinc ion (Zn2+ ). The physiological functions and homeostasis regulation processes of ions are summarized to guide the design of metal ion regulation-based nanomedicines. Then the antitumor mechanisms of various ions-based nanomedicines and some efficient synergistic therapies are highlighted. Finally, the challenges and future developments of ion regulation-based antitumor therapy are also discussed, hoping to provide a reference for finding more effective metal ions and synergistic therapies.

Combining emulsion electrospinning with surface functionalization to fabricate multistructural PLA/CS@ZIF-8 nanofiber membranes toward pH-responsive dual drug delivery

Developing of the multifunctional polymeric carrier for controlled drug release is still one of most challenging task. In this work, a pH-responsive dual drug delivery system was designed and prepared based on the zeolitic imidazolate framework-8 (ZIF-8). The poly(lactic acid)/chitosan (PLA/CS) core-shell nanofiber membranes by emulsion electrospinning, which the hydrophilic drug (Astragalus Polysacharin, APS) was encapsulated in the CS core and the hydrophobic drug (Camptothecin, CPT) was loaded into the PLA shell, respectively. Subsequently, ZIF-8 nanoparticles served as the protective layer were immobilized on the surface of PLA/CS to form multi-structural PLA/CS@ZIF-8 nanofiber membranes. In vitro drug release of nanofiber membranes were studied in the acidic and neutral medium, respectively. The results were that the hydrophilicity and surface roughness of nanofiber membranes rose with increasing of 2-MIM concentrations. The nanofiber membranes also had excellent pH-responsive and controlled release property. Furthermore, the drug release of PLA/CS@ZIF-8 for either APS or CPT were all carried out in a coexisting manner of diffusion and skeleton corrosion. In addition, in vitro cytotoxicity assay indicated nanofiber membranes with good cytocompatibility. Therefore, the multi-structured PLA/CS@ZIF-8 nanofiber membranes has been used as a potential pH-responsive dual drug release system.

Recent advances in metal-organic frameworks: Synthesis, application and toxicity

Metal-organic frameworks (MOFs) are a new class of crystalline porous hybrid materials with high porosity, large specific surface area and adjustable channel structure and biocompatibility, which are being investigated with increasing interest for energy storage and conversion, gas adsorption/separation, catalysis, sensing and biomedicine. However, the practical applications of MOFs make them release into the environment inevitable, posing a threat to humans and organisms. In this article, we cover advances in the currently available MOFs synthesis methods and the emerging applications of MOFs, especially in the biomedical field (therapeutic agents and bioimaging). Additionally, after evaluating the current status of main exposure routes and affecting factors in the field of MOFs-toxicity, the molecular mechanism is also clarified and identified. Knowledge gaps are identified from such a summarization and frontier development are explored for MOFs. Afterwards, we also present the limitations, challenges, and future perspectives in the study of the entire life cycle of MOFs. This review emphasizes the need for a more targeted discussion of the latest, widely used and effective versatile material class in order to exploit the full potential of high-performance and non-toxicity MOFs in the future.

A Novel pH-Responsive Iron Oxide Core-Shell Magnetic Mesoporous Silica Nanoparticle (M-MSN) System Encapsulating Doxorubicin (DOX) and Glucose Oxidase (Gox) for Pancreatic Cancer Treatment

Introduction

This study developed a pancreatic cancer targeted drug delivery system that responds to changes in acidity. The system was based on iron oxide core-shell magnetic mesoporous silica nanoparticles (M-MSNs) to treat pancreatic cancer through combined chemotherapy and starvation therapy.

Methods

Glucose oxidase (Gox) was coupled to the cancer cell surface to reduce glucose availability for cancer cells, exacerbating the heterogeneity of the tumor microenvironment. Reduced pH accelerated the depolymerization of pH-sensitive polydopamine (PDA), thereby controlling the spatial distribution of Gox and release of doxorubicin (DOX) within tumor cells.

Results

Characterization results showed the successful synthesis of DG@M-MSN-PDA-PEG-FA (DG@NPs) with a diameter of 66.02 ± 3.6 nm. In vitro data indicated DG@NPs were highly effective and stable with good cellular uptake shown by confocal laser scanning microscopy (CLSM). DG@NPs exhibited high cytotoxicity and induced apoptosis. Additionally, in vivo experiments confirmed DG@NPs effectively inhibited tumor growth in nude mice with good biosafety. The combination of starvation therapy and chemotherapy facilitated drug release, suggesting DG@NPs as a novel drug delivery system for pancreatic cancer treatment.

Conclusion

This study successfully constructed a doxorubicin release system responsive to acidity changes for targeted delivery in pancreatic cancer, providing a new strategy for combination therapy.

Recent advances in glucose oxidase-based nanocarriers for tumor targeting therapy

Glucose oxidase (GOx) can specifically catalyze the conversion of β-d-glucose into gluconic acid and hydrogen peroxide (H2O2) in the presence of oxygen, making it promising for tumor starvation therapy and oxidative therapy. However, GOx's immunogenicity, poor in vivo stability, short half-life, and potential systemic toxicity, limit its application in cancer therapy. Nanocarriers are capable of improving the pharmacological properties of therapeutic drugs (e.g. stability, circulating half-life, and tumor accumulation) and lower toxicity, hence resolving GOx issues and enhancing its efficacy. Although the application of targeted nanocarriers based on GOx has recently flourished, this field has not yet been reviewed and evaluated. Herein, we initially examined the mechanism of GOx-based nanocarriers for enhanced tumor therapy. Also, we present a comprehensive and up-to-date review that highlights GOx-based nanocarriers for tumor targeting therapy. This review expands on GOx-based nano-targeted combination therapies from both passive and active targeting perspectives, meanwhile, active targeting is further classified into ligand-mediated targeting and physical-mediated targeting. Furthermore, this review also emphasizes the present challenges and promising advancements.

Stimuli-responsive cancer nanomedicines inhibit glycolysis and impair redox homeostasis

The solid tumors are characterized with oxidative stress and metabolic reprogramming, which has been independently used for targeted tumor monotherapy. However, the potential of targeting metabolism-redox circuit in tumor therapy has long been neglected. Herein, we report a hybrid nanocarrier for concurrent targeting of glycolysis and redox balance in the current work. The nanocarriers are made of pH- and ATP-responsive zeolitic imidazolate framework (ZIF-8) as the porous core that was further coated with poloxamer 407 as the steric stabilizer. Two active cargos, glucose oxidase (GOx) and 3-bromopyruvate (3-BrPA) were co-loaded in the core of nanocarrier. GOx is well-known for its ability of producing hydrogen peroxide at the expense of glucose and oxygen. 3-BrPA can reduce oxygen and glucose consumption through glycolysis, which sensitized cancer cells to GOx-induced apoptosis. At the cellular level, the hybrid nanocarrier significantly impaired the redox balance in the liver hepatocellular carcinoma cell line (HepG2), as evidenced by the depletion of glutathione and boost of reactive oxygen species. The potency of hybrid nanocarrier in terms of suppressing HepG2 cell energy metabolism was proven by the exhaustion of ATP. As a consequence, cell viability was greatly reduced. The in vivo efficacy of hybrid nanocarriers was demonstrated in HepG2 tumor-bearing mice. The current work presents an approach of targeting metabolism-redox circuit for tumor treatment, which may enrich the available anti-tumor strategies. STATEMENT OF SIGNIFICANCE: Metabolic alterations and elevated reactive oxygen species (ROS) are two characteristics of cancer. The metabolic patterns of cancer cells are elaborately reprogrammed to enable the rapid propagation of cancer cells. However, the potential of targeting the metabolism-redox circuit in anti-tumor therapy has long been neglected. As a proof-of-concept, we report an engineered stimuli-responsive nanomedicine that can eradicate cancer cells via cooperative glycolysis inhibition and redox impairment. The current work presents an approach of targeting the metabolism-redox circuit for tumor treatment, which may enrich the available anti-tumor strategies.

Recent advances in MOF-bio-interface: a review

Metal-organic frameworks (MOFs), as a class of promising material with adjustable function and controllable structure, have been widely used in the food industry, chemical industry, biological medicine, and sensors. Biomacromolecules and living systems play a critical role in the world. However, the insufficiency in stability, recyclability, and efficiency, significantly impedes their further utilization in slightly harsh conditions. MOF-bio-interface engineering effectively address the above-mentioned shortages of biomacromolecules and living systems, and thereby attracting considerable attentions. Herein, we systematically review the achievements in the area of MOF-bio-interface. In particular, we summarize the interface between MOFs and proteins (enzymes and non-enzymatic proteins), polysaccharides, DNA, cells, microbes, and viruses. Meanwhile, we discuss the limitations of this approach and propose future research directions. We expect that this review could provide new insights and inspire new research efforts towards life science and material science.

Progress and prospects of nanozymes for enhanced antitumor therapy

Nanozymes are nanomaterials with mimicked enzymatic activity, whose catalytic activity can be designed by changing their physical parameters and chemical composition. With the development of biomedical and material science, artificially created nanozymes have high biocompatibility and can catalyze specific biochemical reactions under biological conditions, thus playing a vital role in regulating physiological activities. Under pathological conditions, natural enzymes are limited in their catalytic capacity by the varying reaction conditions. In contrast, compared to natural enzymes, nanozymes have advantages such as high stability, simplicity of modification, targeting ability, and versatility. As a result, the novel role of nanozymes in medicine, especially in tumor therapy, is gaining increasing attention. In this review, function and application of various nanozymes in the treatment of cancer are summarized. Future exploration paths of nanozymes in cancer therapies based on new insights arising from recent research are outlined.

Enzyme-immobilized metal-organic frameworks: From preparation to application

As a class of widely used biocatalysts, enzymes possess advantages including high catalytic efficiency, strong specificity and mild reaction condition. However, most free enzymes have high requirements on the reaction environment and are easy to deactivate. Immobilization of enzymes on nanomaterial-based substrates is a good way to solve this problem. Metal-organic framework (MOFs), with ultra-high specific surface area and adjustable porosity, can provide a large space to carry enzymes. And the tightly surrounded protective layer of MOFs can stabilize the enzyme structure to a great extent. In addition, the unique porous network structure enables selective mass transfer of substrates and facilitates catalytic processes. Therefore, these enzyme-immobilized MOFs have been widely used in various research fields, such as molecule/biomolecule sensing and imaging, disease treatment, energy and environment protection. In this review, the preparation strategies and applications of enzymes-immobilized MOFs are illustrated and the prospects and current challenges are discussed.

A Nanounit Strategy Disrupts Energy Metabolism and Alleviates Immunosuppression for Cancer Therapy

Aberrant energy metabolism not only endows tumor cells with unlimited proliferative capacity but also contributes to the establishment of the glucose-deficient/lactate-rich immunosuppressive tumor microenvironment (ITM) impairing antitumor immunity. Herein, a novel metabolic nanoregulator (D/B/CQ@ZIF-8@CS) was developed by enveloping 2-deoxy-d-glucose (2-DG), BAY-876, and chloroquine (CQ) into zeolitic imidazolate framework-8 (ZIF-8) to simultaneously deprive the energy/nutrition supply of tumor cells and relieve the ITM for synergetic tumor starvation-immunotherapy. Aerobic glycolysis, glucose uptake, and autophagy flux could be concurrently blocked by D/B/CQ@ZIF-8@CS, cutting off the nutrition/energy supply and the source of lactate. Furthermore, inhibition of glucose uptake and aerobic glycolysis could effectively reverse the glucose-deficient/lactate-rich ITM, thus functionally inactivating regulatory T cells and augmenting anti-CTLA-4 immunotherapy. Such a two-pronged strategy would provide new insights for the design of metabolic intervention-based synergistic cancer therapy.

A Copper-Based Biosensor for Dual-Mode Glucose Detection

Glucose is a source of energy for daily activities of the human body and is regarded as a clinical biomarker, due to the abnormal glucose level in the blood leading to many endocrine metabolic diseases. Thus, it is indispensable to develop simple, accurate, and sensitive methods for glucose detection. However, the current methods mainly depend on natural enzymes, which are unstable, hard to prepare, and expensive, limiting the extensive applications in clinics. Herein, we propose a dual-mode Cu₂O nanoparticles (NPs) based biosensor for glucose analysis based on colorimetric assay and laser desorption/ionization mass spectrometry (LDI MS). Cu₂O NPs exhibited excellent peroxidase-like activity and served as a matrix for LDI MS analysis, achieving visual and accurate quantitative analysis of glucose in serum. Our proposed method possesses promising application values in clinical disease diagnostics and monitoring.