Glucose Oxidase-Instructed Multimodal Synergistic Cancer Therapy

Harnessing Endogenous Stimuli for Responsive Materials in Theranostics

Materials that respond to endogenous stimuli are being leveraged to enhance spatiotemporal control in a range of biomedical applications from drug delivery to diagnostic tools. The design of materials that undergo morphological or chemical changes in response to specific biological cues or pathologies will be an important area of research for improving efficacies of existing therapies and imaging agents, while also being promising for developing personalized theranostic systems. Internal stimuli-responsive systems can be engineered across length scales from nanometers to macroscopic and can respond to endogenous signals such as enzymes, pH, glucose, ATP, hypoxia, redox signals, and nucleic acids by incorporating synthetic bio-inspired moieties or natural building blocks. This Review will summarize response mechanisms and fabrication strategies used in internal stimuli-responsive materials with a focus on drug delivery and imaging for a broad range of pathologies, including cancer, diabetes, vascular disorders, inflammation, and microbial infections. We will also discuss observed challenges, future research directions, and clinical translation aspects of these responsive materials.

Urchin-Shaped Metal Organic/Hydrogen-Bonded Framework Nanocomposite as a Multifunctional Nanoreactor for Catalysis-Enhanced Synergetic Therapy

Ultrasound (US)-induced sonodynamic therapy (SDT) is an efficient and precise method against tumor, and the integration of multiple cancer therapies has been proved as a promising strategy for better therapeutic effects. Herein, for the first time, a multifunctional nanoreactor has been fabricated by integrating Fe-MIL-88B-NH₂, PFC-1, and glucose oxidase (GO_x) to form urchin-like Fe-MIL-88B-NH₂@PFC-1-GO_x (MPG) nanoparticles as Fenton's reagent, a sonosensitizer, and a tumor microenvironment (TME) modulator. In detail, MPG can generate ^•OH for chemodynamic therapy (CDT) and deplete glutathione (GSH) to alleviate the antioxidant ability of cancer cells. Moreover, catalase (CAT)-like MPG can react with H₂O₂ to generate O₂ for relieving hypoxia in TME, enhancing GO_x-catalyzed glucose oxidation to produce H₂O₂ and gluconic acid. Then, the regenerated H₂O₂ can promote the Fenton reaction to achieve GO_x catalysis-enhanced CDT. Owing to its large π-electron conjugated system, MPG also serves as an ideal sonosensitizer, realizing a burst generation of ¹O₂ under US irradiation for efficient SDT. Therefore, the tumor treatment will be notably enhanced by MPG-based synergetic CDT/SDT/starvation therapy via a series of cascade reactions. Overall, this work develops a versatile nanoreactor with improved tumor treatment effectiveness and broadens the application prospects of porous materials in the field of biomedical research.

Chiral Control of Carbon Dots via Surface Modification for Tuning the Enzymatic Activity of Glucose Oxidase

Chiral carbon dots (CDs) integrated the advantages of achiral CDs and the unique chiral property, which expand the prospect of the biological applications of CDs. However, the structure control and the origin of chirality for chiral CDs remain unclear. Herein, chiral CDs were obtained by thermal polymerization of chiral amino acids and citric acid, and their handedness of chirality could be controlled by adjusting the reaction temperature, which leads to different kinds of surface modifications. With aliphatic amino acids as a chiral source, all of the CDs that reacted at different temperatures (90-200 °C) have the same handedness of the chiral source. But with aromatic amino acids as a chiral source, CDs with maintained or inversed handedness compared with the chiral source could be obtained by adjusting the reaction temperature. Below a temperature of 120 °C, the chiral source was modified with CDs by esterification and transferred the handedness of chirality; at high temperatures (above 150 °C), which mainly connected by amidation accompanying with the formation of rigid structure generated by the π conjugation between the aromatic nucleus of chiral source and the carbon core of CDs, caused the inversing of the chiral signal. Further, we investigated the chiral effects of CDs on the glucose oxidase activity for a highly sensitive electrochemical biosensor.

Nanocatalytic Theranostics with Glutathione Depletion and Enhanced Reactive Oxygen Species Generation for Efficient Cancer Therapy

Chemodynamic therapy (CDT) is an emerging therapy method that kills cancer cells by converting intracellular hydrogen peroxide (H₂ O₂ ) into highly toxic hydroxyl radicals (^• OH). To overcome the current limitations of the insufficient endogenous H₂ O₂ and the high concentration of glutathione (GSH) in tumor cells, an intelligent nanocatalytic theranostics (denoted as PGC-DOX) that possesses both H₂ O₂ self-supply and GSH-elimination properties for efficient cancer therapy is presented. This nanoplatform is constructed by a facile one-step biomineralization method using poly(ethylene glycol)-modified glucose oxidase (GOx) as a template to form biodegradable copper-doped calcium phosphate nanoparticles, followed by the loading of doxorubicin (DOX). As an enzyme catalyst, GOx can effectively catalyze intracellular glucose to generate H₂ O₂ , which not only starves the tumor cells, but also supplies H₂ O₂ for subsequent Fenton-like reaction. Meanwhile, the redox reaction between the released Cu²⁺ ions and intracellular GSH will induce GSH depletion and reduce Cu²⁺ to Fenton agent Cu⁺ ions, and then trigger the H₂ O₂ to generate ^• OH by a Cu⁺ -mediated Fenton-like reaction, resulting in enhanced CDT efficacy. The integration of GOx-mediated starvation therapy, H₂ O₂ self-supply and GSH-elimination enhanced CDT, and DOX-induced chemotherapy, endow the PGC-DOX with effective tumor growth inhibition with minimal side effects in vivo.

A Multifunctional Nanovaccine based on L-Arginine-Loaded Black Mesoporous Titania: Ultrasound-Triggered Synergistic Cancer Sonodynamic Therapy/Gas Therapy/Immunotherapy with Remarkably Enhanced Efficacy

In order to achieve better antitumor therapeutic efficacy and inhibit tumor metastasis, a multifunctional nanovaccine based on L-arginine (LA)-loaded black mesoporous titania (BMT) is fabricated. In this system, LA is utilized as the exogenous NO supplementation for gas therapy, and BMT is served as acoustic sensitizer for sonodynamic therapy. The ultrasound (US) as the exogenous stimulus can simultaneously trigger BMT and LA to produce singlet oxygen (¹ O₂ ) and NO gas at tumor sites, respectively. Interestingly, ¹ O₂ from US-excited BMT can promote the oxidation of LA to produce more NO. The high concentration of ¹ O₂ and NO in cancer cell can cause intracellular strong oxidative stress level and DNA double-strand breaks to induce cancer cell apoptosis ultimately. The US-triggered BMT@LA "nanovaccine" combining with immune checkpoint inhibitor PD-L1 antibody (αPD-L1) can induce strong antitumor immune response thus effectively killing primary tumors and further inhibiting metastatic tumors. Hence, BMT@LA-based "nanovaccine" combining with αPD-L1 checkpoint blockade treatment can realize synergetic sonodynamic/gas/immunotherapy with enhanced antitumor therapeutic effects.

Decoupling hydrogen production from water oxidation by integrating a triphase interfacial bioelectrochemical cascade reaction

Water electrolysis to produce H₂ is a promising strategy for generating a renewable fuel. However, the sluggish-kinetics and low value-added anodic oxygen evolution reaction (OER) restricts the overall energy conversion efficiency. Herein we report a strategy of boosting H₂ production at low voltages by replacing OER with a bioelectrochemical cascade reaction at a triphase bioanode. In the presence of oxygen, oxidase enzymes can convert biomass into valuable products, and concurrently generate H₂O₂ that can be further electrooxidized at the bioanode. Benefiting from the efficient oxidase kinetics at an oxygen-rich triphase bioanode and the more favorable thermodynamics of H₂O₂ oxidation than that of OER, the cell voltage and energy consumption are reduced by ~0.70 V and ~36%, respectively, relative to regular water electrolysis. This leads to an efficient H₂ production at the cathode and valuable product generation at the bioanode. Integration of a bioelectrochemical cascade into the water splitting process provides an energy-efficient and promising pathway for achieving a renewable fuel.

H2O2-independent chemodynamic therapy initiated from magnetic iron carbide nanoparticle-assisted artemisinin synergy

Chemodynamic therapy (CDT) is a booming technology that utilizes Fenton reagents to kill tumor cells by transforming intracellular H2O2 into reactive oxygen species (ROS), but insufficient endogenous H2O2 makes it difficult to attain satisfactory antitumor results.

Synergistically enhanced multienzyme catalytic nanoconjugates for efficient cancer therapy

Tumors are complex and highly variable, making it difficult for a single treatment strategy to be significantly effective for cancer therapy. Herein, we report a robust cascade biomimetic nanoplatform that integrates chemiluminescence-induced photodynamic therapy (CL-PDT), Fenton reaction-based chemodynamic therapy (CDT), and glucose oxidase (GOD)-mediated starvation therapy to synergistically enhance cancer treatment. For the nanoplatform of CPPO@porphyrin-MOF@Cancer cell membrane-GOD (C1@M@C2G), the ferric ion-linked porphyrin-MOF can trigger a Fenton reaction to reach CDT, the carried CPPO as an energy donor is used to excite a photo-sensitive porphyrin-MOF in situ to generate singlet oxygen (1O2) for PDT, GOD catalyzes glucose into H2O2 and gluconic acid to realize starvation therapy, and the cancer cell membrane wrapped onto the nanoparticle plays a key role in homologous targeting, which is conducive to achieving better therapeutic effects. Significantly, the porphyrin-MOF with catalase-like activity can generate O2 to effectively relieve tumor hypoxia, thereby enhancing the catalytic effect of GOD and the efficacy of PDT. Additionally, the produced H2O2 and gluconic acid can further improve the CPPO-H2O2-triggered CL-PDT and promote the low pH-dependence Fenton reaction-based CDT, respectively. Both in vitro and in vivo studies showed that the constructed nanoplatform displays an excellent cooperative anti-tumor performance, so we firmly believe that this simple nanoplatform broadens the pathway to fight against cancer through effective cascade catalysis.

Recent Advances in Hyperthermia Therapy-Based Synergistic Immunotherapy

The past decades have witnessed hyperthermia therapy (HTT) as an emerging strategy against malignant tumors. Nanomaterial-based photothermal therapy (PTT) and magnetic hyperthermia (MHT), as highly effective and noninvasive treatment models, offer advantages over other strategies in the treatment of different types of tumors. However, both PTT and MHT cannot completely cure cancer due to recurrence and distal metastasis. In recent years, cancer immunotherapy has attracted widespread attention owing to its capability to activate the body's own natural defense to identify, attack, and eradicate cancer cells. Significant efforts have been devoted to studying the activated immune responses caused by hyperthermia-ablated tumors. In this article, the synergistic mechanism of HTT in immunotherapy, including immunogenic cell death and reversal of the immunosuppressive tumor microenvironment is discussed. The reports of the combination of HTT or HTT-based multimodal therapy with immunotherapy, including immunoadjuvant exploitation, immune checkpoint blockade therapy, and adoptive cellular immunotherapy are summarized. As highlighted, these strategies could achieve synergistically enhanced therapeutic outcomes against both primary tumors and metastatic lesions, prevent cancer recurrence, and prolong the survival period. Finally, current challenges and prospective developments in HTT-synergized immunotherapy are also reviewed.

Dual catalytic cascaded nanoplatform for photo/chemodynamic/starvation synergistic therapy

In this study, manganese dioxide (MnO₂) was attached to prussian blue (PB) by a one-pot method to prepare PBMO. Then, the GOD was loaded onto PBMO through the electrostatic interaction of hyaluronic acid (HA) to form tumor-targeted nanoplatform (PBMO-GH). Hydrogen peroxide (H₂O₂) and gluconic acid were produced through the GOD-catalyzed enzymatic reaction. Meanwhile, PB could not only catalyze H₂O₂ for oxygen generation to further promote glucose consumption but also possess the property of photothermal conversion. As a result, glucose was continuously consumed to achieve the starvation therapy (ST), and the photothermal therapy (PTT) could be realized under near-infrared (NIR) light. Besides, the Mn²⁺ generated by the reaction of MnO₂ with glutathione (GSH) could exert Fenton-like reaction to produce highly toxic hydroxyl radicals (·OH) from H₂O₂, which thereby realized self-reinforcing chemodynamic therapy (CDT). In vitro and in vivo experiments demonstrated that PBMO-GH could effectively inhibit the growth of tumor cells via ST/CDT/PTT synergistic effect. Therefore, the as-prepared nanoplatform for multi-modal therapy will provide a promising paradigm for overcoming cancer.

Nanozyme-Incorporated Biodegradable Bismuth Mesoporous Radiosensitizer for Tumor Microenvironment-Modulated Hypoxic Tumor Thermoradiotherapy

Solid tumors inevitably develop radioresistance due to low oxygen partial pressure in the tumor microenvironment. Despite numerous attempts, there are still few effective ways to avoid the hypoxia-induced poor radiotherapeutic effect. To overcome this problem, platinum (Pt) nanodots were fabricated into a mesoporous bismuth (Bi)-based nanomaterial to construct a biodegradable nanocomposite BiPt-folic acid-modified amphiphilic polyethylene glycol (PFA). BiPt-PFA could act as a radiosensitizer to enhance the absorption of X-rays at the tumor site and simultaneously trigger response behaviors related to the tumor microenvironment due to the enrichment of materials in the tumor area. During this process, the Bi-based component consumed glutathione via coordination, thus altering the oxidative stress balance, while Pt nanoparticles catalyzed the decomposition of hydrogen peroxide to generate oxygen, thereby relieving tumor hypoxia. Both Pt and Bi thus co-modulated the tumor microenvironment to improve the radiotherapeutic effect. In addition, Pt dots in BiPt-PFA had strong near-infrared absorption ability and created an intensive photothermal therapeutic effect. Modulation of the tumor microenvironment could thus improve the therapeutic effect in hypoxic tumors by a combination of photothermal therapy and enhanced radiotherapy. BiPt-PFA, as a biodegradable nanocomposite, may thus modulate the tumor microenvironment to enhance the hypoxic tumor therapeutic effect by thermoradiotherapy.

Biodegradable Multifunctional Nanotheranostic Based on Ag2S-Doped Hollow BSA-SiO2 for Enhancing ROS-Feedback Synergistic Antitumor Therapy

Stimuli-responsive silica nanoparticles are an attractive therapeutic agent for effective tumor ablation, but the responsiveness of silica nanoagents is limited by intrastimulation level and silica framework structure. Herein, a biodegradable hollow SiO₂-based nanosystem (Ag₂S-GOx@BHS NYs) is developed by a novel one-step dual-template (bovine serum albumin (BSA) and cetyltrimethylammonium bromide (CTAB)) synthetic strategy for image-guided therapy. The Ag₂S-GOx@BHS NYs can be specifically activated in the tumor microenvironment via a self-feedback mechanism to achieve reactive oxygen species (ROS)-induced multistep therapy. In response to the inherent acidity and H₂O₂ at the tumor sites, Ag₂S-GOx@BHS would accelerate the structural degradation while releasing glucose oxidase (GOx), which could efficiently deplete intratumoral glucose to copious amounts of gluconic acid and H₂O₂. More importantly, the sufficient H₂O₂ not only acts as a reactant to generate Ag⁺ from Ag₂S for metal-ion therapy and improves the oxidative stress but also combines with gluconic acid results in the self-accelerating degradation process. Moreover, the released Ag₂S nanoparticles can help the Ag₂S-GOx@BHS NYs realize the second near-infrared window fluorescence (NIR-II FL) and photoacoustic (PA) imaging-guided precise photothermal therapy (PTT). Taken together, the development of a self-feedback nanosystem may open up a new dimension for a highly effective multistep tumor therapy.

A self-accelerated biocatalyst for glucose-initiated tumor starvation and chemodynamic therapy

A self-accelerated biocatalyst (Bio-Cat) was developed based on BSA and GOx crosslinked nanoproteins for glucose-initiated tumor starvation and chemodynamic therapy. Bio-Cat could catalyze the glucose to elevate the intracellular H₂O₂ level and accelerate the conversion of Fe³⁺/Fe²⁺, resulting in an effective starvation therapy and an accelerated Fenton reaction for chemodynamic therapy.

Carrier-Free Platinum Nanomedicine for Targeted Cancer Therapy

Numerous nanomedicines have been developed to improve the efficiency and safety of conventional anticancer drugs; however, the complexities in carrier materials and functional integration make it challenging to promote these candidates for clinical translation. In this study, a facile method to prepare carrier-free anticancer nanodrug with inherent bone targeting and osteoclastogenesis inhibition capabilities is reported. Phytic acid, a naturally occurring and nontoxic product, is reacted with cisplatin to form uniform nanoparticles of different sizes. The prepared nanoparticles possess high drug loading and pH-responsive drug release behaviors. Phytic acid in the nanomedicine ensures high bone targeting and osteoclastogenesis inhibition, and the released platinum drugs triggered by tumor extracellular acidity eradicate tumor cells. The nanomedicine around 100 nm shows high anticancer activity and much reduced side effects in a subcutaneous breast cancer model when compared with cisplatin. In addition, it shows high accumulation at osteolytic lesions, and efficiently inhibits tumor growth and tumor-associated osteolysis in a bone metastatic breast cancer model. Here, a facile and efficient strategy to prepare carrier-free nanomedicines with high anticancer drug loading, inherent bone targeting, and osteoclast inhibitory activities for cancer therapy is provided.

A robust hybrid nanozyme@hydrogel platform as a biomimetic cascade bioreactor for combination antitumor therapy

The development of highly effective and minimally invasive approaches for cancer treatment is the ultimate goal. Herein, an injectable hybrid hydrogel as a biomimetic cascade bioreactor is designed for combination antitumor therapy by providing spatiotemporally-controlled and long-term delivery of therapeutic agents. This hybrid nanozyme@hydrogel (hPB@gellan) is doped with Prussian blue (PB) nanoparticles via the in situ nanoprecipitation method in the polysaccharide gellan matrix. The obtained PB nanoparticles have a small size of 10 nm and play dual roles as a photothermal agent with a photothermal conversion efficiency of 59.6% and as a nanozyme to decompose hydrogen peroxide into oxygen. By incorporating glucose oxidase (GOD) into the hybrid hydrogel, a cascade bioreactor is formed for PB-promoted glucose consumption. Owing to its shear-thinning and self-recovery properties, the hybrid hydrogel is locally administered into tumors, and shows long-term resistance against body clearance and metabolism. The in vivo antitumor results demonstrate that the tumors in the group of combined photothermal and starvation therapy (GOD/hPB@gellan + NIR) are greatly eliminated with a tumor suppression rate of 99.7% 22 days after the treatment. The outstanding antitumor performance is attributed to the main attack by NIR-triggered hyperthermia and the holding attack by GOD-mediated starvation from the catalytic bioreactor of the hybrid hydrogel. Taking into consideration the advantages of biosafety, simple synthetic approaches and facile manipulation in treatment, the hybrid hydrogel has great potential for clinical translation.

Oxygen self-enriched single-component "black carbon nitride" for near-infrared phototheranostics

Single component agent-based near-infrared phototheranostics has captivated researchers in cancer treatment over recent decades. However, the current single-component agents rarely alleviate the hypoxic microenvironment in tumor cells, which severely limits the development of photodynamic therapy. Here, we report a new phototheranostic agent, single-component black graphite carbon nitride nanoparticles (named CN-B NPs), synthesized through thermal copolymerization. Compared with unmodified graphitic carbon nitride (g-C3N4), the absorption of CN-B NPs in the near-infrared region was enhanced. Through in vitro and in vivo studies, we demonstrated that CN-B NPs can be used as a near-infrared phototheranostic agent in both normoxia and hypoxia, simultaneously allowing infrared thermal/photoacoustic imaging and photodynamic/photothermal co-therapy, thereby resulting in remarkable inhibition of tumor growth. This approach could provide a new method to achieve multimodal phototheranostics using a single-component material.

Quantitative Assessment of Endosomal Escape of Various Endocytosed Polymer-Encapsulated Molecular Cargos upon Photothermal Heating

Encapsulated molecular cargos are efficiently endocytosed by cells. For cytosolic delivery, understanding the dynamic process of cargos release from the carrier vehicles used for encapsulation and the lysosomes where the carrier vehicles are trapped (which in general is the bottleneck), followed by diffusion in the cytosol is important for improving drug/gene delivery strategies. A methodology is reported to image this process on a millisecond scale and to quantitatively analyze the data. Polyelectrolyte capsules with embedded gold nanostars to encapsulate 43 fluorescent molecular cargos with diverse properties, ranging from small fluorophores to fluorescently labeled proteins, siRNA, etc., are used. By short laser irradiation intracellular release of the molecular cargos from endocytosed capsules into the cytosol is triggered, and their intracellular spreading is imaged. Most of the released molecular cargos evenly distribute inside the entire cell, while others are enriched in certain cell compartments. The time the different molecular cargos take to distribute within cells, i.e., the spreading time, is used as a quantifier. Quantitative analysis reveals that intracellular spread cannot be described by free diffusion, but is determined by interaction of the molecular cargo with intracellular components.

Biomineralization: An Opportunity and Challenge of Nanoparticle Drug Delivery Systems for Cancer Therapy

Biomineralization is a common process in organisms to produce hard biomaterials by combining inorganic ions with biomacromolecules. Multifunctional nanoplatforms are developed based on the mechanism of biomineralization in many biomedical applications. In the past few years, biomineralization-based nanoparticle drug delivery systems for the cancer treatment have gained a lot of research attention due to the advantages including simple preparation, good biocompatibility, degradability, easy modification, versatility, and targeting. In this review, the research trends of biomineralization-based nanoparticle drug delivery systems and their applications in cancer therapy are summarized. This work aims to promote future researches on cancer therapy based on biomineralization. Rational design of nanoparticle drug delivery systems can overcome the bottleneck in the clinical transformation of nanomaterials. At the same time, biomineralization has also provided new research ideas for cancer treatment, i.e., targeted therapy, which has significantly better performance.

Nanoplatform-based cascade engineering for cancer therapy

Various therapeutic techniques have been studied for treating cancer precisely and effectively, such as targeted drug delivery, phototherapy, tumor-specific catalytic therapy, and synergistic therapy, which, however, evoke numerous challenges due to the inherent limitations of these therapeutic modalities and intricate biological circumstances as well. With the remarkable advances of nanotechnology, nanoplatform-based cascade engineering, as an efficient and booming strategy, has been tactfully introduced to optimize these cancer therapies. Based on the designed nanoplatforms, pre-supposed cascade processes could be triggered under specific conditions to generate/deliver more therapeutic species or produce stronger tumoricidal effects inside tumors, aiming to achieve cancer therapy with increased anti-tumor efficacy and diminished side effects. In this review, the recent advances in nanoplatform-based cascade engineering for cancer therapy are summarized and discussed, with an emphasis on the design of smart nanoplatforms with unique structures, compositions and properties, and the implementation of specific cascade processes by means of endogenous tumor microenvironment (TME) resources and/or exogenous energy inputs. This fascinating strategy presents unprecedented potential in the enhancement of cancer therapies, and offers better controllability, specificity and effectiveness of therapeutic functions compared to the corresponding single components/functions. In the end, challenges and prospects of such a burgeoning strategy in the field of cancer therapy will be discussed, hopefully to facilitate its further development to meet the personalized treatment demands.

Methionine-Based pH and Oxidation Dual-Responsive Block Copolymer: Synthesis and Fabrication of Protein Nanogels

In this paper, we synthesized a block copolymer containing pendent thioether functionalities by reversible addition-fragmentation chain transfer polymerization of a tert-butyloxycarbonyl (Boc)-l-methionine-(2-methacryloylethyl)ester (Boc-METMA) monomer using a poly(ethylene glycol) (PEG)-based chain transfer agent. The deprotection of Boc groups resulted in an oxidation and pH dual-responsive cationic block copolymer PEG-b-P(METMA). The block copolymer PEG-b-P(METMA) possessing protonable amine groups was water-soluble at pH < 6.0 and self-assembled to form spherical micelles at pH > 6.0. In the presence of H₂O₂, the micelles first became highly swollen with time and completely disassembled at last, demonstrating the H₂O₂-responsive feature because of the oxidation of hydrophobic thioether to hydrophilic sulfoxide. The anticancer drug curcumin (Cur) was entrapped in the polymeric micelles and the Cur-loaded micelles displayed a H₂O₂-triggered release profile as well as a pH-dependent release behavior, making PEG-b-P(METMA) micelles promising nanocarriers for reactive oxygen species-responsive drug delivery. Taking advantage of the protonated amine groups, the cationic polyelectrolyte PEG-b-P(METMA) formed polyion complex micelles with glucose oxidase (GOx) through electrostatic interactions at pH 5.8. By cross-linking the cores of PIC micelles with glutaraldehyde, the PIC micelles were fixed to generate stable GOx nanogels under physiological conditions. The GOx nanogels were glucose-responsive and exhibited glucose-dependent H₂O₂-generation activity in vitro and improved storage and thermal stability of GOx. Cur can be encapsulated in the GOx nanogels, and the Cur-loaded GOx nanogels demonstrate the glucose-responsive release profile. The GOx nanogels displayed high cytotoxicity to 4T1 cells and were effectively internalized by the cells. Therefore, these GOx nanogels have potential applications in the areas of cancer starvation and oxidation therapy.

Colorectal Tumor Microenvironment-Activated Bio-Decomposable and Metabolizable Cu2 O@CaCO3 Nanocomposites for Synergistic Oncotherapy

Rational design of tumor microenvironment (TME)-activated nanocomposites provides an innovative strategy to construct responsive oncotherapy. In colorectal cancer (CRC), the specific physiological features are the overexpressed endogenous H₂ S and slightly acidic microenvironment. Here, a core-shell Cu₂ O@CaCO₃ nanostructure for CRC "turn-on" therapy is reported. With CaCO₃ responsive to pH decomposition and Cu₂ O responsive to H₂ S sulfuration, Cu₂ O@CaCO₃ can be triggered "on" into the therapeutic mode by the colorectal TME. When the CaCO₃ shell decomposes and releases calcium in acidic colorectal TME, the loss of protection from the CaCO₃ shell exposes the Cu₂ O core to be sulfuretted by H₂ S to form metabolizable Cu₃₁ S₁₆ nanocrystals that gain remarkably strong near-infrared absorption. After modifying hyaluronic acid, Cu₂ O@CaCO₃ can achieve synergistic CRC-targeted and TME-triggered photothermal/photodynamic/chemodynamic/calcium-overload-mediated therapy. Moreover, it is found that the generation of hyperthermia and oxidative stress from Cu₂ O@CaCO₃ nanocomposites can efficiently reprogram the macrophages from the M2 phenotype to the M1 phenotype and initiate a vaccine-like immune effect after primary tumor removal, which further induces an immune-favorable TME and intense immune responses for anti-CD47 antibody to simultaneously inhibit CRC distant metastasis and recurrence by immunotherapy.

Tumor-Targeted Cascade Nanoreactor Based on Metal-Organic Frameworks for Synergistic Ferroptosis-Starvation Anticancer Therapy

Although ferroptosis therapy has been proven to be a promising strategy for cancer treatment, its efficacy still might be limited by insufficient H₂O₂ supply in tumor tissue. Herein, we designed a cancer cell membrane-cloaked cascade nanoreactor based on ferric metal-organic frameworks (MOF) and glucose oxidase (GOx) decoration for synergistic ferroptosis-starvation anticancer therapy. The GOx can catalyze glucose to generate sufficient H₂O₂ for ferroptosis therapy, and the glucose consumption caused by GOx can be utilized as another attractive cancer treatment strategy called starvation therapy. When the nanoreactor reached tumor sites, high concentration of GSH reduced Fe³⁺ to trigger structure collapse of MOF and release Fe²⁺ and GOx catalyzed the oxidation of glucose to generate H₂O₂. Then Fenton reaction happened between H₂O₂ and Fe²⁺ to produce hydroxyl radicals (^•OH) and promoted ferroptosis therapy. With these cascade reactions, the synergistic ferroptosis-starvation anticancer therapy was realized. Furthermore, the cancer cell membrane endows the nanoreactor homologous targeting and immune escaping ability, which facilitated the nanoreactor to accumulate into tumor site with high efficiency. The nanoreactor exhibits high efficiency for tumor suppression with the in situ consumed and produced compounds, which can promote the development of precise cooperative cancer therapy with spatiotemporal controllability.

Porous Pt Nanospheres Incorporated with GOx to Enable Synergistic Oxygen-Inductive Starvation/Electrodynamic Tumor Therapy

Glucose-oxidase (GOx)-mediated starvation by consuming intracellular glucose has aroused extensive exploration as an advanced approach for tumor treatment. However, this reaction of catalytic oxidation by GOx is highly dependent on the on-site oxygen content, and thus starvation therapy often suffers unexpected anticancer outcomes due to the intrinsic tumorous hypoxia. Herein, porous platinum nanospheres (pPts), incorporated with GOx molecules (PtGs), are synthesized to enable synergistic cancer therapy. In this system, GOx can effectively catalyze the oxidation of glucose to generate H2O2, while pPt triggers the decomposition of both endogenous and exogenous H2O2 to produce considerable content of O2 to facilitate the glucose consumption by GOx. Meanwhile, pPt induces remarkable content of intracellular reactive oxygen species (ROS) under an alternating electric field, leading to cellular oxidative stress injury and promotes apoptosis following the mechanism of electrodynamic therapy (EDT). In consequence, the PtG nanocomposite exhibits significant anticancer effect both in vitro and in vivo. This study has therefore demonstrated a fascinating therapeutic platform enabling oxygen-inductive starvation/EDT synergistic strategy for effective tumor treatment.

A Nanomedicine Fabricated from Gold Nanoparticles-Decorated Metal-Organic Framework for Cascade Chemo/Chemodynamic Cancer Therapy

The incorporation of new modalities into chemotherapy greatly enhances the anticancer efficacy combining the merits of each treatment, showing promising potentials in clinical translations. Herein, a hybrid nanomedicine (Au/FeMOF@CPT NPs) is fabricated using metal-organic framework (MOF) nanoparticles and gold nanoparticles (Au NPs) as building blocks for cancer chemo/chemodynamic therapy. MOF NPs are used as vehicles to encapsulate camptothecin (CPT), and the hybridization by Au NPs greatly improves the stability of the nanomedicine in a physiological environment. Triggered by the high concentration of phosphate inside the cancer cells, Au/FeMOF@CPT NPs effectively collapse after internalization, resulting in the complete drug release and activation of the cascade catalytic reactions. The intracellular glucose can be oxidized by Au NPs to produce hydrogen dioxide, which is further utilized as chemical fuel for the Fenton reaction, thus realizing the synergistic anticancer efficacy. Benefitting from the enhanced permeability and retention effect and sophisticated fabrications, the blood circulation time and tumor accumulation of Au/FeMOF@CPT NPs are significantly increased. In vivo results demonstrate that the combination of chemotherapy and chemodynamic therapy effectively suppresses the tumor growth, meantime the systemic toxicity of this nanomedicine is greatly avoided.

GSH depletion liposome adjuvant for augmenting the photothermal immunotherapy of breast cancer

The high redox level of tumor microenvironment inhibits the oxidation treatment and the immune response. Here, we innovatively develop maleimide liposome (ML) adjuvants to promote immunogenic cell death (ICD) induction and dendritic cells (DCs) maturation by glutathione (GSH) depletion for augmenting the photothermal immunotherapy of breast cancer. The ML effectively depletes the intracellular GSH and up-regulates reactive oxygen species (ROS) in both tumor cells and DCs. In tumor cells, the ROS boosted the ABTS·⁺ production to activate photothermal-induced ICD. In DCs, it relieved the immunosuppression, promoting DC maturation (57%) and antigen presenting. As a result of the ML assistant, the therapeutic systems improved the infiltration of CD8⁺ T cells to 53% in tumor tissues, eliciting strong abscopal effect and antimetastasis effect. The MLs were believed to be a superior candidate of adjuvants for enhancing immune response and cancer therapeutic efficacy.

Hollow Magnetic Nanocatalysts Drive Starvation-Chemodynamic-Hyperthermia Synergistic Therapy for Tumor

Magnetic hyperthermia therapy (MHT) has been considered as an excellent alternative for treatment of deep tumor tissue; however, up-regulation of heat shock proteins (HSPs) impairs its hyperthermal therapeutic effect. Reactive oxygen species (ROS) and competitive consumption of ATP are important targets that can block excessive HSP generation. We developed a magnetic nanocatalytic system comprised of glucose oxidase (GOD)-loaded hollow iron oxide nanocatalysts (HIONCs) to drive starvation-chemodynamic-hyperthermia synergistic therapy for tumor treatment. The Fe²⁺ present in HIONCs contributed to ROS generation via the Fenton reaction, relieving thermo-resistance and inducing cell apoptosis by chemodynamic action. The Fenton effect was enhanced through the conditions created by increased MHT-related temperature, GOD-mediated H₂O₂ accumulation, and elevated tumor microenvironment acidity. The HIONCs catalase-like activity facilitated conversion of H₂O₂ to oxygen, thereby replenishing the oxygen levels. We further demonstrated that locally injected HIONCs-GOD effectively inhibited tumor growth in PC3 tumor-bearing mice. This study presents a multifunctional nanocarrier system driving starvation-chemodynamic-magnetic-thermal synergistic therapy via ROS and oxygen modulation for prostate tumor treatment.

Biomimetic Metal-Organic Framework Composite-Mediated Cascade Catalysis for Synergistic Bacteria Killing

Encapsulating nanoparticles/biomolecules into metal-organic freamworks (MOFs) has proven to be highly effective in creating new functions during their applications. However, it is highly desirable yet remains challenging to achieve the synergy of specific functions between the MOF host and guest species. Herein, inspired by the natural multienzyme system, a novel MOF composite biomimetic structure based on the coencapsulation of glucose oxidase (GOx) and l-arginine (l-Arg) into Cu-MOFs (CuBDC) with Fenton-like catalytic activity is designed for achieving the synergistic antibacterial effect. Once activated by GOx-catalyzed glucose oxidation, a large amount of oxygen radicals, toxic ONOO^-, and NO are rapidly produced over this well-designed l-Arg/GOx@CuBDC through a double-cascade reaction. Thanks to the synergy of highly reactive species, outstanding antibacterial effects (bacterial inactivation ≥97%) are observed at very low doses (38 μg mL^-1 for Escherichia coli and 3.8 μg mL^-1 for Staphylococcus aureus). In addition, the in vivo experiment in mice demonstrated that the as-prepared l-Arg/GOx@CuBDC has good biocompatibility, indicating its good potential in practical applications. Such a biomimetic multienzyme system proposes a new design idea for highly efficient antibiosis as well as even therapy for tumors.

Two-stage activated nano-truck enhanced specific aggregation and deep delivery for synergistic tumor ablation

Although nanomedicines have shown high performance in tumor theranostics, their anticancer activity is still limited by the drug delivery capacity, especially lack of targeting capability, poor tumor accumulation, and insufficient tumor deep-penetration. To address this challenge, a high biocompatibility nano-truck (BMP NT) with a two-stage delivery mechanism is designed and developed to achieve the precision therapeutic efficacy of cancer. In view of the enhanced permeability retention (EPR) effect, the surface cleavable layer of BMP NTs can be selectively removed by the overexpressed MMP-2 in a tumor-microenvironment to expose the hydrophobic segments for an induced "braking effect" strategy, resulting in a significant increase in tumor accumulation. Once internalized into cancer cells with the overproduced glutathione (GSH) and H₂O₂, the BMP NTs undergo the second-stage "unloading process" to release Mn²⁺ ions and ultrasmall Bi₂S₃@BSA nanoparticles, and the obtained Mn²⁺ ions can act as a Fenton-like catalyst for continuously catalyzing the endogenous H₂O₂ into highly toxic hydroxyl radicals (˙OH) for CDT. The GSH depletion will in turn improve the Mn²⁺-H₂O₂ reaction, further enhancing CDT efficiency. Meanwhile, the ultrasmall Bi₂S₃@BSA endows BMP NTs with excellent photothermal conversion ability to generate local hyperthermia and accelerate the intratumoral Fenton process, thus leading to an effective tumor therapeutic outcome in the synergistic function of CDT/photothermal therapy (PTT). Moreover, the BMP NTs can be used for in situ self-generation magnetic resonance imaging (MRI) and photoacoustic (PA) imaging to guide precision cancer therapy.

Prodrug-Based Nanoreactors with Tumor-Specific In Situ Activation for Multisynergistic Cancer Therapy

Efficient drug delivery into tumor cells while bypassing many biological barriers is still a challenge for cancer therapy. By taking advantage of the palladium (Pd)-mediated in situ activation of a prodrug and the glucose oxidase (GOD)-based β-d-glucose oxidation reaction, we developed a multisynergistic cancer therapeutic platform that combined doxorubicin (DOX)-induced chemotherapy with GOD-mediated cancer-orchestrated oxidation therapy and cancer starvation therapy. In the present work, we first synthesized DOX prodrugs (pDOXs) and temporarily assembled them with β-cyclodextrins to reduce their toxic side effects. Then, a nanoreactor was constructed by synthesizing Pd⁰ nanoparticles in situ within the pores of mesoporous silica nanoparticles for the conversion of pDOX into the active anticancer drug. Furthermore, GOD was introduced to decrease the pH of the tumor microenvironment and induce cancer-orchestrated oxidation/starvation therapy by catalyzing β-d-glucose oxidation to form hydrogen peroxide (H₂O₂) and gluconic acid. Our study provides a new strategy that employs a cascade chemical reaction to achieve combined orchestrated oxidation/starvation/chemotherapy for the synergistic killing of cancer cells and the suppression of tumor growth.

A Glucose/Oxygen-Exhausting Nanoreactor for Starvation- and Hypoxia-Activated Sustainable and Cascade Chemo-Chemodynamic Therapy

Fenton reaction-mediated chemodynamic therapy (CDT) can kill cancer cells via the conversion of H₂ O₂ to highly toxic HO•. However, problems such as insufficient H₂ O₂ levels in the tumor tissue and low Fenton reaction efficiency severely limit the performance of CDT. Here, the prodrug tirapazamine (TPZ)-loaded human serum albumin (HSA)-glucose oxidase (GOx) mixture is prepared and modified with a metal-polyphenol network composed of ferric ions (Fe³⁺ ) and tannic acid (TA), to obtain a self-amplified nanoreactor termed HSA-GOx-TPZ-Fe³⁺ -TA (HGTFT) for sustainable and cascade cancer therapy with exogenous H₂ O₂ production and TA-accelerated Fe³⁺ /Fe²⁺ conversion. The HGTFT nanoreactor can efficiently convert oxygen into HO• for CDT, consume glucose for starvation therapy, and provide a hypoxic environment for TPZ radical-mediated chemotherapy. Besides, it is revealed that the nanoreactor can significantly elevate the intracellular reactive oxygen species content and hypoxia level, decrease the intracellular glutathione content, and release metal ions in the tumors for metal ion interference therapy (also termed "ion-interference therapy" or "metal ion therapy"). Further, the nanoreactor can also increase the tumor's hypoxia level and efficiently inhibit tumor growth. It is believed that this tumor microenvironment-regulable nanoreactor with sustainable and cascade anticancer performance and excellent biosafety represents an advance in nanomedicine.

A mitochondria-targeted anticancer nanoplatform with deep penetration for enhanced synergistic sonodynamic and starvation therapy

Sonodynamic therapy (SDT), as an emerging technique, gives rise to reactive oxygen species (ROS)-induced apoptosis of tumor cells. However, nonselective enrichment and unsatisfactory penetration depth of sonosensitizers in tumor tissues limit its application. In this study, we synthesized core/shell (glucose oxidase (GOx) in the core/hematoporphyrin monomethyl ether (HMME) and IR780 in the shell) structured polylactic-co-glycolic acid (PLGA) nanoparticles (NPs) with deep tumor penetration and mitochondrial targeting capability for synergistic sonodynamic and starvation therapy. After passing through the endothelial space of tumor vasculatures, by virtue of IR780, these NPs can selectively accumulate towards cancer cells/sites, especially in mitochondria and diffuse into deep tumour centres. Upon ultrasound (US) exposure, the overproduced ROS cause tumor cell apoptosis. Sonodynamic effects can be amplified by mitochondrial targeting because mitochondria are susceptible to ROS. GOx blocks glucose (energy) supply, further suppressing the growth of malignant tumors. This synergistic therapy exhibited a superb response to treatment (4.7-fold lower tumor growth in volume than the control group). In addition, these NPs also serve as excellent photoacoustic (PA)/fluorescent (FL) imaging contrast agents to simultaneously monitor and guide cancer therapy. This study paves a promising way to achieve an ideal strategy for cancer therapy.

Self-degrading graphene sheets for tumor therapy

Low biodegradability of graphene derivatives and related health risks are the main limiting factors for their in vivo biomedical applications. Here, we present the synthesis of enzyme-functionalized graphene sheets with self-degrading properties under physiological conditions and their applications in tumor therapy. The synergistic enzyme cascade glucose oxidase and myeloperoxidase are covalently conjugated to the surface of graphene sheets and two-dimensional (2D) platforms are obtained that can produce sodium hypochlorite from glucose. The enzyme-functionalized graphene sheets with up to 289 nm average size are degraded into small pieces (≤40 nm) by incubation under physiological conditions for 24 h. Biodegradable graphene sheets are further loaded with doxorubicin and their ability for tumor therapy is evaluated in vitro and in vivo. The laser-triggered release of doxorubicin in combination with the enzymatic activity of the functionalized graphene sheets results in a synergistic antitumor activity. Taking advantage of their neutrophil-like activity, fast biodegradability, high photo- and chemotherapeutic effects, the novel two-dimensional nanoplatforms can be used for tumor therapeutic applications.

Complementary autophagy inhibition and glucose metabolism with rattle-structured polydopamine@mesoporous silica nanoparticles for augmented low-temperature photothermal therapy and in vivo photoacoustic imaging

Rattle-structured nanoparticles with movable cores, porous shells and hollow interiors have shown great effectiveness in drug delivery and cancer theranostics. Targeting autophagy and glucose have provided alternative strategies for cancer intervention therapy. Herein, rattle-structured polydopamine@mesoporous silica nanoparticles were prepared for in vivo photoacoustic (PA) imaging and augmented low-temperature photothermal therapy (PTT) via complementary autophagy inhibition and glucose metabolism.

Methods: The multifunctional rattle-structured nanoparticles were designed with the nanocore of PDA and the nanoshell of hollow mesoporous silica (PDA@hm) via a four-step process. PDA@hm was then loaded with autophagy inhibitor chloroquine (CQ) and conjugated with glucose consumer glucose oxidase (GOx) (PDA@hm@CQ@GOx), forming a corona-like structure nanoparticle.

Results: The CQ and GOx were loaded into the cavity and decorated onto the surface of PDA@hm, respectively. The GOx-mediated tumor starvation strategy would directly suppress the expression of HSP70 and HSP90, resulting in an enhanced low-temperature PTT induced by PDA nanocore. In addition, autophagy inhibition by the released CQ made up for the loss of low-temperature PTT and starvation efficiencies by PTT- and starvation-activated autophagy, realizing augmented therapy efficacy. Furthermore, the PDA nanocore in the PDA@hm@CQ@GOx could be also used for PA imaging.

Conclusion: Such a “drugs” loaded rattle-structured nanoparticle could be used for augmented low-temperature PTT through complementarily regulating glucose metabolism and inhibiting autophagy and in vivo photoacoustic imaging.

Programmable NIR-II Photothermal-Enhanced Starvation-Primed Chemodynamic Therapy using Glucose Oxidase-Functionalized Ancient Pigment Nanosheets

Chemodynamic therapy (CDT) has attracted considerable attention recently, but the poor reaction kinetics restrict its practical utility in clinic. Herein, glucose oxidase (GOx) functionalized ancient pigment nanosheets (SrCuSi₄ O₁₀ , SC) for programmable near-infrared II (NIR-II) photothermal-enhanced starvation primed CDT is developed. The SC nanosheets (SC NSs) are readily exfoliated from SC bulk suspension in water and subsequently functionalized with GOx to form the nanocatalyst (denoted as SC@G NSs). Upon laser irradiation, the photothermal effect of SC NSs can enhance the catalytic activity of GOx for NIR-II photothermal-enhanced starvation therapy, which effectively eliminates intratumoral glucose and produces abundant hydrogen peroxide (H₂ O₂ ). Importantly, the high photothermal-conversion efficiency (46.3%) of SC@G NSs in second biological window permits photothermal therapy of deep-seated tumors under the guidance of NIR-II photoacoustic imaging. Moreover, the acidity amplification due to gluconic acid generation will in turn accelerate the degradation of SC NSs, facilitating the release of strontium (Sr) and copper (Cu) ions. Both the elevated H₂ O₂ and the released ions will prime the Cu²⁺ /Sr²⁺ -H₂ O₂ reaction for enhanced CDT. Thus, a programmable NIR-II photothermal-enhanced starvation primed CDT is established to combat cancer with minimal side effects.

Self-Assembled Multiple-Enzyme Composites for Enhanced Synergistic Cancer Starving-Catalytic Therapy

Inspired by the particularity of tumor microenvironments, including acidity and sensibility to reactive oxygen species (ROS), advanced and smart responsive nanomaterials have recently been developed. The present study synthesized tumor-targeted and pH-sensitive supramolecular micelles that self-assembled via host-guest recognition. The micelles consumed intratumoral glucose and lactate via loading with glucose oxidase (GOD) and lactate oxidase (LOD). Intratumoral glucose and lactate were converted into hydrogen peroxide (H₂O₂) and were sequentially reduced to highly toxic hydroxyl radicals (^•OH) via the peroxidase (POD)-like activity of the loaded C-dot nanozymes. Tumor-killing effects were observed via cascade catalytic reactions. After an intravenous injection, the nanocomposite exhibited an excellent tumor-targeted ability with good biocompatibility, which demonstrated its effective antitumor effect. The nanocomposite effectively combined starvation and catalytic therapies and exerted a synergistic anticancer effect with minimal side effects and without external addition.

pH-Responsive Cascaded Nanocatalyst for Synergistic Like-Starvation and Chemodynamic therapy

A tumor microenvironment (TME) responsive cascade nanocatalyst was built based on copper-embedded hollow mesoporous silica (HMSN-Cu) decorated with glucose oxidase (GOD) on the surface, realizing tumor-selected cascade catalyst for elegant combination of starving therapy and chemodynamic therapy. Specifically, benefited from the strong demand for glucose metabolism in tumor cells, this HMSN-Cu-GOD could catalyze rich glucose into H2O2 in the presence of O2, along with localized declined pH in situ to in turn degrade HMSN-Cu and thus release Cu2+/Cu+. Importantly, abound hydroxyl radical (•OH) with high oxidative activity generated in the Fenton reaction between H2O2 and Cu2+/Cu+. Interesting, the high-expressed GSH and exacerbated hypoxia in tumor cells, will facilitate accumulation of Cu+ with much higher reaction efficiency, further enhanced Chemodynamic therapy (CDT) efficiency. Compared with monotherapy, in vitro and vivo tumor inhibition experiments demonstrated the superior synergistic effect of CDT and starving therapy based on a simple but effective biodegradable nanosystem.

Janus γ-Fe2O3/SiO2-based nanotheranostics for dual-modal imaging and enhanced synergistic cancer starvation/chemodynamic therapy

Multimodal cancer synergistic therapy exhibited remarkable advantages over monotherapy in producing an improved therapeutic efficacy. In this work, Janus-type γ-Fe₂O₃/SiO₂ nanoparticles (JFSNs) are conjugated with glucose oxidase (GOx) for synergistic cancer starvation/chemodynamic therapy. The γ-Fe₂O₃ hemisphere of JFSNs can perform photoacoustic/T₂ magnetic resonance dual-modal imaging of tumors. GOx on the surface of JFSNs catalyzes the decomposition of glucose and produces H₂O₂ for cancer starvation therapy. Subsequently, the γ-Fe₂O₃ hemisphere catalyzes the disproportionation of H₂O₂ to generate highly reactive hydroxyl radicals in an acidic tumor microenvironment. The close distance between GOx and JFSNs ensures adequate contact between the γ-Fe₂O₃ hemisphere and its substrate H₂O₂, thus enhancing the catalytic efficiency. This synergy of glucose depletion, biotoxic H₂O₂ and hydroxyl radicals significantly suppresses 4T1 mammary tumor growth with minimal adverse effects.