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

Biodegradable Nanocatalyst with Self-Supplying Fenton-like Ions and H2O2 for Catalytic Cascade-Amplified Tumor Therapy

Therapeutic nanosystems triggered by a specific tumor microenvironment (TME) offer excellent safety and selectivity in the treatment of cancer by in situ conversion of a less toxic substance into effective anticarcinogens. However, the inherent antioxidant systems, hypoxic environment, and insufficient hydrogen peroxide (H₂O₂) in tumor cells severely limit their efficacy. Herein, a new strategy has been developed by loading the chemotherapy prodrug disulfiram (DSF) and coating glucose oxidase (GOD) on the surface of Cu/ZIF-8 nanospheres and finally encapsulating manganese dioxide (MnO₂) nanoshells to achieve efficient DSF-based cancer chemotherapy and dual-enhanced chemodynamic therapy (CDT). In an acidic TME, the nanocatalyst can biodegrade rapidly and accelerate the release of internal active substances. The outer layer of MnO₂ depletes glutathione (GSH) to destroy the reactive oxygen defensive mechanisms and achieves continuous oxygen generation, thus enhancing the catalytic efficiency of GOD to burst H₂O₂. Benefiting from the chelation reaction between the released Cu²⁺ and DSF, a large amount of cytotoxic CuET products is generated, and the Cu⁺ are concurrently released, thereby achieving efficient chemotherapy and satisfactory CDT efficacy. Furthermore, the release of Mn²⁺ can initiate magnetic resonance imaging signals for the tracking of the nanocatalyst.

Recent Advances of Manganese-Based Hybrid Nanomaterials for Cancer Precision Medicine

Cancer precision medicine (CPM) could tailor the best treatment for individual cancer patients, while imaging techniques play important roles in its application. With the characteristics of noninvasion, nonionized, radiation-free, multidimensional imaging function, and real-time monitoring, magnetic resonance imaging (MRI) is an effective way for early tumor detection, and it has become a tower of strength in CPM imaging techniques. Due to linkage with nephrogenic systemic fibrosis (NSF), gadolinium (Gd)-based contrast agent (CA), which was long used in MRI, has been restricted by the Food and Drug Administration (FDA). In this review, we would like to introduce the manganese (Mn)-based CAs that could significantly increase the safety of MRI CAs by realizing more superior performance and functions simultaneously in the diagnosis and treatment of tumors. Also, recent advances in Mn-based hybrid nanomaterials for CPM are summarized and discussed.

Activatable Biomineralized Nanoplatform Remodels the Intracellular Environment of Multidrug-Resistant Tumors for Enhanced Ferroptosis/Apoptosis Therapy

Ferroptosis is a new form of regulated cell death with significant therapeutic prospect, but its application against drug-resistant tumor cells is challenging due to their ability to effuse antitumor agents via p-glycoprotein (P-gp) and anti-lipid peroxidation alkaline intracellular environment. Herein, an amorphous calcium phosphate (ACP)-based nanoplatform is reported for the targeted combinational ferroptosis/apoptosis therapy of drug resistant tumor cells by blocking the MCT4-mediated efflux of lactic acid (LA). The nanoplatform is fabricated through the biomineralization of doxorubicin-Fe²⁺ (DOX-Fe²⁺ ) complex and MCT4-inhibiting siRNAs (siMCT4) and can release them to the tumor cytoplasm after the hydrolysis of ACP and dissociation of DOX-Fe²⁺ in the acidic lysosomes. siMCT4 can inhibit MCT4 expression and force the glycolysis-generated lactic acid (LA) to remain in cytoplasm for rapid acidification. The nanoplatform-induced remodeling of the tumor intracellular environment can not only interrupt the ATP supply required for P-gp-dependent DOX effusion to enhance H₂ O₂ production, but also increase the overall catalytic efficiency of Fe²⁺ for the initiation and propagation of lipid peroxidation. These features could act in concert to enhance the efficacy of the combinational ferroptosis/chemotherapy and prolong the survival of tumor-bearing mice. This study may provide new avenues for the treatment of multidrug-resistant tumors.

Emerging Roles of Energy Metabolism in Ferroptosis Regulation of Tumor Cells

Ferroptosis is a new form of regulated cell death, which is characterized by the iron-dependent accumulation of lethal lipid peroxides and involved in many critical diseases. Recent reports revealed that cellular energy metabolism activities such as glycolysis, pentose phosphate pathway (PPP), and tricarboxylic acid cycle are involved in the regulation of key ferroptosis markers such as reduced nicotinamide adenine dinucleotide phosphate (NADPH), glutathione (GSH), and reactive oxygen species (ROS), therefore imposing potential regulatory roles in ferroptosis. Remarkably, tumor cells can activate adaptive metabolic responses to inhibit ferroptosis for self-preservation such as the upregulation of glycolysis and PPP. Due to the rapid proliferation of tumor cells and the intensified metabolic rate, tumor energy metabolism has become a target for disrupting the redox homeostasis and induce ferroptosis. Based on these emerging insights, regulatory impact of those-tumor specific metabolic aberrations is systematically characterized, such as rewired glucose metabolism and metabolic compensation through glutamine utilization on ferroptosis and analyzed the underlying molecular mechanisms. Additionally, those ferroptosis-based therapeutic strategies are also discussed by exploiting those metabolic vulnerabilities, which may open up new avenues for tumor treatment in a clinical context.

MicroRNA-Triggered Nanozymes Cascade Reaction for Tumor-Specific Chemodynamic Therapy

Off-target toxicity and insufficient hydroxyl radicals (^. OH) generation limit the further clinical application of nanozymes in chemodynamic therapy (CDT). Herein, we designed and constructed a microRNA-triggered nanozyme cascade platform for enhanced tumor-specific chemodynamic therapy. The nanozyme-based cascade reaction could be triggered successfully by the high expression of microRNA in cancer cells to generate more ^. OH, thus exhibiting excellent tumor-specific therapeutic performance. Our work provides a new dimension for tumor-specific chemodynamic therapy.

Fenton/Fenton-like metal-based nanomaterials combine with oxidase for synergistic tumor therapy

Chemodynamic therapy (CDT) catalyzed by transition metal and starvation therapy catalyzed by intracellular metabolite oxidases are both classic tumor treatments based on nanocatalysts. CDT monotherapy has limitations including low catalytic efficiency of metal ions and insufficient endogenous hydrogen peroxide (H₂O₂). Also, single starvation therapy shows limited ability on resisting tumors. The “metal-oxidase” cascade catalytic system is to introduce intracellular metabolite oxidases into the metal-based nanoplatform, which perfectly solves the shortcomings of the above-mentioned monotherapiesIn this system, oxidases can not only consume tumor nutrients to produce a “starvation effect”, but also provide CDT with sufficient H₂O₂ and a suitable acidic environment, which further promote synergy between CDT and starvation therapy, leading to enhanced antitumor effects. More importantly, the “metal-oxidase” system can be combined with other antitumor therapies (such as photothermal therapy, hypoxia-activated drug therapy, chemotherapy, and immunotherapy) to maximize their antitumor effects. In addition, both metal-based nanoparticles and oxidases can activate tumor immunity through multiple pathways, so the combination of the “metal-oxidase” system with immunotherapy has a powerful synergistic effect. This article firstly introduced the metals which induce CDT and the oxidases which induce starvation therapy and then described the “metal-oxidase” cascade catalytic system in detail. Moreover, we highlight the application of the “metal-oxidase” system in combination with numerous antitumor therapies, especially in combination with immunotherapy, expecting to provide new ideas for tumor treatment.

Tumor-activatable biomineralized nanotherapeutics for integrative glucose starvation and sensitized metformin therapy

Metformin is a clinically-approved anti-diabetic drug with emerging antitumor potential, but its antitumor activity is highly susceptible to local glucose abundance. Herein, we construct a nanotherapeutic platform based on biocompatible constituents to sensitize tumor cells for metformin therapy via cooperative glucose starvation. The nanoplatform was synthesized through the spontaneous biomineralization of glucose oxidase (GOx) and metformin in amorphous calcium phosphate nanosubstrate, which was further modified with polyethylene glycol and cRGD ligands. This biomineralized nanosystem could efficiently deliver the therapeutic payloads to tumor cells in a targeted and bioresponsive manner. Here GOx could catalyze the oxidation of glucose into gluconic acid and H₂O₂, thus depleting the glucose in tumor intracellular compartment while accelerating the release of the entrapped therapeutic payloads. The selective glucose deprivation would not only disrupt tumor energy metabolism, but also upregulate the PP2A regulatory subunit B56δ and sensitize tumor cells to the metformin-induced CIP2A inhibition, leading to efficient apoptosis induction via PP2A-GSK3β-MCL-1 axis with negligible side effects. This study may offer new avenues for targeted tumor therapy in the clinical context.

pH-Sensitive Polymeric Vesicles for GOx/BSO Delivery and Synergetic Starvation-Ferroptosis Therapy of Tumor

Typical glucose oxidase (GOx)-based starvation therapy is a promising strategy for tumor treatment; however, it is still difficult to achieve an effective therapeutic effect via a single starvation therapy. Herein, we designed a pH-sensitive polymeric vesicle (PV) self-assembled by histamine-modified chondroitin sulfate (CS-his) for codelivery of GOx and l-buthionine sulfoximine (BSO). GOx can consume glucose to induce the starvation therapy after the PVs reach cancer cell. Moreover, the product H₂O₂ will be reduced by a high concentration of glutathione (GSH) in the tumor cell, resulting in a reduction of the GSH content. The released BSO finally further reduced the GSH level. As a result, the signaling pathway of the ferroptosis will be activated. The in vivo results demonstrated that GOx/BSO@CS PVs exhibit a good inhibitory effect on the growth of 4T1 tumors in mice. Thus, this work provides a facile strategy to prepare pH-sensitive nanomedicine for synergistic starvation-ferroptosis therapy of tumor.

Mitochondrial-targeting nanoprodrugs to mutually reinforce metabolic inhibition and autophagy for combating resistant cancer

Abnormal energy metabolism is one of the hallmarks of cancer and closely linked to therapy resistance. However, existing metabolic inhibitors suffer from inefficient cell enrichment and therapeutic effects. In this work, we developed an effective strategy to mutually reinforce the metabolic inhibition and autophagy for enhanced tumor killing efficacy and combating resistant cancer. First, mitochondrial homing moiety triphenylphosphonium and metabolic inhibitor lonidamine were grafted onto polylysine. After self-assembly of this functionalized polylysine, ferrocene and glucose oxidase were immobilized to afford additional chemotherapy functions, and the final product was named as FG/T-Nanoprodrug. Effective mitochondrial targeting and metabolic inhibition were observed in resistant cancer cells. In addition, owing to the inhibited metabolism, less glucose is consumed to allow FG/T-Nanoprodrug to produce excess reactive oxygen species (ROS) by glucose oxidase and ferrocene. The enhanced chemodynamic therapy increases the mitochondrial permeability to promote the release of cytochrome c from mitochondria, ultimately induces high levels of autophagy. The FG/T-Nanoprodrug demonstrated superior mutually reinforcing of metabolic inhibition (up to 3.7-fold compared to free lonidamine) and autophagy (up to 125.3-fold compared to free lonidamine) to effectively kill resistant cancer cell both in vitro and in vivo. Overall, this strategy could pave a new way to efficient treatment of resistant cancer and other metabolically abnormal diseases.

A polydopamine-gated biodegradable cascade nanoreactor for pH-triggered and photothermal-enhanced tumor-specific nanocatalytic therapy

Despite the great potential of cascade catalytic reactions in tumor treatment, uncontrolled catalytic activities in vivo lead to inevitable off-target toxicity to normal tissues, which greatly hampers their clinical conversion. Herein, an intelligent cascade nanoreactor (hMnO₂-Au@PDA, hMAP) was constructed by depositing glucose oxidase (GOx)-mimicking ultrasmall gold nanoparticles (Au NPs) into honeycomb-shaped manganese oxide (hMnO₂) nanostructures and then coating them with polydopamine (PDA) to achieve pH-responsive and photothermal-enhanced nanocatalytic therapy. Upon exposure to the mild acidic tumor microenvironment (TME), the PDA gatekeeper would collapse, and the inner hMnO₂ could simultaneously deplete glutathione (GSH) and generate Mn²⁺, while a considerable amount of H₂O₂ produced from the oxidation of glucose by GOx-mimicking Au NPs could accelerate the Mn²⁺-mediated Fenton-like reaction, yielding sufficient highly toxic ˙OH. More importantly, the pH-responsive cascade reaction between Au NPs and hMnO₂ could be further enhanced by localized hyperthermia induced from PDA under near-infrared (NIR) laser irradiation, thereby inducing significant cell apoptosis in vitro and tumor inhibition in vivo. This work provided a promising paradigm by innovatively designing a TME-responsive and photothermal-enhanced cascade catalytic nanoreactor for safe and efficient cancer therapy.

Advanced Cancer Starvation Therapy by Simultaneous Deprivation of Lactate and Glucose Using a MOF Nanoplatform

Recent investigations reveal that lactate is not a waste product but a major energy source for cells, especially in the mitochondria, which can support cellular survival under glucose shortage. Accordingly, the new understanding of lactate prompts to target it together with glucose to pursue a more efficient cancer starvation therapy. Herein, zeolitic imidazolate framework-8 (ZIF-8) nanoplatforms are used to co-deliver α-cyano-4-hydroxycinnamate (CHC) and glucose oxidase (GOx) and fulfill the task of simultaneous depriving of lactate and glucose, resulting in a new nanomedicine CHC/GOx@ZIF-8. The synthesis conditions are carefully optimized in order to yield monodisperse and uniform nanomedicines, which will ensure reliable and steady therapeutic properties. Compared with the strategies aiming at a single carbon source, improved starvation therapy efficacy is observed. Besides, more than boosting the energy shortage, CHC/GOx@ZIF-8 can block the lactate-fueled respiration and relieve solid tumor hypoxia, which will enhance GOx catalysis activity, depleting extra glucose, and producing more cytotoxic H2 O2 . By the synergistically enhanced anti-tumor effect, both in vitro and in vivo cancer-killing efficacies of CHC/GOx@ZIF-8 show twice enhancements than the GOx mediated therapy. The results demonstrate that the dual-depriving of lactate and glucose is a more advanced strategy for strengthening cancer starvation therapy.

Fenton Metal Nanomedicines for Imaging-guided Combinatorial Chemodynamic Therapy against Cancer

Chemodynamic therapy (CDT) is considered as a promising modality for selective cancer therapy, which is realized via Fenton reaction-mediated decomposition of endogenous H₂O₂ to produce toxic hydroxyl radical (•OH) for tumor ablation. While extensive efforts have been made to develop CDT-based therapeutics, their in vivo efficacy is usually unsatisfactory due to poor catalytic activity limited by tumor microenvironment, such as anti-oxidative systems, insufficient H₂O₂, and mild acidity. To mitigate these issues, we have witnessed a surge in the development of CDT-based combinatorial nanomedicines with complementary or synergistic mechanisms for enhanced tumor therapy. By virtue of their bio-imaging capabilities, Fenton metal nanomedicines (FMNs) are equipped with intrinsic properties of imaging-guided tumor therapies. In this critical review, we summarize recent progress of this field, focusing on FMNs for imaging-guided combinatorial tumor therapy. First, various Fenton metals with inherent catalytic performances and imaging properties, including Fe, Cu and Mn, were introduced to illustrate their possible applications for tumor theranostics. Then, CDT-based combinatorial systems were reviewed by incorporating many other treatment means, including chemotherapy, photodynamic therapy (PDT), sonodynamic therapy (SDT), photothermal therapy (PTT), starvation therapy and immunotherapy. Next, various imaging approaches based on Fenton metals were presented in detail. Finally, challenges are discussed, and future prospects are speculated in the field to pave way for future developments.

Encapsulation of Enzymes in Metal-Phenolic Network Capsules for the Trigger of Intracellular Cascade Reactions

Nanoengineered capsules encapsulated with functional cargos (e.g., enzymes) are of interest for various applications including catalysis, bioreactions, sensing, and drug delivery. Herein, we report a facile strategy to engineer enzyme-encapsulated metal-phenolic network (MPN) capsules using enzyme-loaded zeolitic imidazolate framework nanoparticles (ZIF-8 NPs) as templates, which can be removed in a mild condition (e.g., ethylenediaminetetraacetic acid (EDTA) solution). The capsule size (from 250 nm to 1 μm) and thickness (from 9.8 to 33.7 nm) are well controlled via varying the template size and coating time, respectively. Importantly, MPN capsules encapsulated with enzymes (i.e., glucose oxidase) can trigger the intracellular cascade reaction via the exhaustion of glucose to produce H₂O₂ and subsequently generate toxic hydroxyl radicals (^•OH) based on the Fenton reaction via the reaction between H₂O₂ and iron ions in MPN coatings. The intracellular cascade reaction for the generation of ^•OH is efficient to inhibit cancer cell viability, which is promising for the application in chemodynamic therapy.

Synergistic Multimodal Cancer Therapy Using Glucose Oxidase@CuS Nanocomposites

Multimodal nanotherapeutic cancer treatments are widely studied but are often limited by their costly and complex syntheses that are not easily scaled up. Herein, a simple formulation of glucose-oxidase-coated CuS nanoparticles was demonstrated to be highly effective for melanoma treatment, acting through a synergistic combination of glucose starvation, photothermal therapy, and synergistic advanced chemodynamic therapy enabled by near-infrared irradiation coupled with Fenton-like reactions that were enhanced by endogenous chloride.

Metal peroxides for cancer treatment

In recent years, metal peroxide (MO2) such as CaO2 has received more and more attention in cancer treatment. MO2 is readily decompose to release metal ions and hydrogen peroxide in the acidic tumor microenvironment (TME), resulting metal ions overloading, decreased acidity and elevated oxidative stress in TME. All of these changes making MO2 an excellent tumor therapeutic agent. Moreover, by combining MO2 with photosensitizers, enzymes or Fenton reagents, MO2 can assist and promote various tumor therapies such as photodynamic therapy and chemodynamic therapy. In this review, the synthesis and modification methods of MO2 are introduced, and the representative studies of MO2-based tumor monotherapy and combination therapy are discussed in detail. Finally, the current challenges and prospects of MO2 in the field of tumor therapy are emphasized to promote the development of MO2-based cancer treatment.

Phosphate-Degradable Nanoparticles Based on Metal-Organic Frameworks for Chemo-Starvation-Chemodynamic Synergistic Antitumor Therapy

Chemodynamic therapy (CDT) was regarded as a promising approach for tumor treatment. However, owing to the insufficient amount of endogenous hydrogen peroxide (H2O2) in tumor cells, the efficacy of CDT was limited. In this study, we designed phosphate-responsive nanoparticles (denoted as MGDFT NPs) based on metal-organic frameworks, which were simultaneously loaded with drug doxorubicin (DOX) and glucose oxidases (GOx). The decorated GOx could act as a catalytic nanomedicine for the response to the abundant glucose in the tumor microenvironment, generating a great deal of H2O2, which would enhance the Fenton reaction and produce toxic hydroxyl radicals (·OH). Meanwhile, the growth of tumors would also be inhibited by overconsuming the intratumoral glucose, which was the "fuel" for cell proliferation. When the nanoparticles entered into tumor cells, a high concentration of phosphate induced structure collapse, releasing the loaded DOX for chemotherapy. Furthermore, the decoration of target agents endowed the nanoparticles with favorable target ability to specific tumor cells and mitochondria. Consequently, the designed MGDFT NPs displayed desirable synergistic therapeutic effects via combining chemotherapy, starvation therapy, and enhanced Fenton reaction, facilitating the development of multimodal precise antitumor therapy.

Precise engineering of acorn-like Janus nanoparticles for cancer theranostics

The anisotropic Janus nanoparticles (JNPs) provide synergistic effects by concentrating multiple properties on a single carrier. Herein, we reported a novel and simple approach to fabricate acorn-like poly(acrylic acid)-mesoporous calcium phosphate/polydopamine (PAA-mCaP/PDA) JNPs, which were selectively functionalized with methoxy-poly(ethylene glycol)thiol (PEG-SH) on PDA domains to obtain superior stability, while the other mCaP sides served as a storage space and passage for the anti-cancer drug of doxorubicin (DOX). The unique acorn-like PAA-mCaP/PDA-PEG JNPs were utilized as novel theranostic agents for photoacoustic (PA) imaging-guided synergistic cancer chemo-phototherapy. More importantly, this synthetic strategy can be applied to synthesize various mesoporous Janus nanocarriers, paving the way toward designed synthesis of acorn-like JNPs in nanomedicine, biosensing and catalysis. STATEMENT OF SIGNIFICANCE: The distinct acorn-like poly(acrylic acid)-mesoporous calcium phosphate/polydopamine Janus nanoparticles (PAA-mCaP/PDA JNPs) with a spherical-shaped PAA-mCaP core and PDA half-shell were fabricated for the first time. To achieve superior stability, the acorn-like PAA-mCaP/PDA JNPs were selectively functionalized with methoxy-poly(ethylene glycol)thiol (PEG-SH) on PDA domains to obtain acorn-like PAA-mCaP/PDA-PEG JNPs. The resultant acorn-like PAA-mCaP/PDA-PEG JNPs own an excellent biocompatibility, high drug-loading contents, good photothermal conversion efficiency, photoacoustic (PA) imaging capacity and pH/NIR dual-responsive properties, enabling the acorn-like JNPs to be applied for PA imaging-guided synergistic cancer chemo-phototherapy. More importantly, the synthetic approach could be extended to prepare acorn-like mesoporous inorganic substances/PDA JNPs for specific applications.

Interfacially Engineered ZnxMn1-xS@Polydopamine Hollow Nanospheres for Glutathione Depleting Photothermally Enhanced Chemodynamic Therapy

Fenton-like reactions driven by manganese-based nanostructures have been widely applied in cancer treatment owing to the intrinsic physiochemical properties of these nanostructures and their improved sensitivity to the tumor microenvironment. In this work, Zn_xMn_1-xS@polydopamine composites incorporating alloyed Zn_xMn_1-xS and polydopamine (PDA) were constructed, in which the Fenton-like reactions driven by Mn ions can be tuned by a controllable release of Mn ions in vitro and in vivo. As a result, the Zn_xMn_1-xS@PDA exhibited good biocompatibility with normal cells but was specifically toxic to cancer cells. In addition, the shell thickness of PDA was carefully investigated to obtain excellent specific toxicity to cancer cells and promote synergistic chemodynamic and photothermal therapies. Overall, this work highlights an alternative strategy for fabricating high-performance, multifunctional composite nanostructures for a combined cancer treatment.

Glucose oxidase and Fe3O4/TiO2/Ag3PO4 co-embedded biomimetic mineralization hydrogels as controllable ROS generators for accelerating diabetic wound healing

The hyperglycemic environment and the presence of bacterial infections delay the healing of diabetic wounds. Herein, glucose oxidase (GOx) and Fe₃O₄/TiO₂/Ag₃PO₄ were embedded in a polyacrylic acid-calcium phosphate (PAA-CaPs@Nps@GOx) hydrogel through an in situ biomimetic mineralization approach. The GOx encapsulation efficiency was 96.75% and exhibited exceptional enzyme activity stability. Moreover, the co-immobilization of GOx and Fe₃O₄/TiO₂/Ag₃PO₄ nanoparticles generated a simple and multifunctional antibacterial platform with the advantages of decreasing blood glucose concentration and efficiently producing reactive oxygen species (ROS). In addition, the degradation rate of the hydrogel was controlled by regulating the concentration of phosphate thus controlling the release of Fe₃O₄/TiO₂/Ag₃PO₄ and GOx. As a result, both the potential toxicity and oxidative stress associated with the antimicrobial biomaterial can be controlled within the body therefore potentially preventing detriment. In vivo results indicated that the PAA-CaPs@Nps@GOx hydrogel effectively promoted diabetic wound healing and showed great potential for clinical applications of chronic wound management.

Biomimetic Nanoreactor for Cancer Eradication via Win-Win Cooperation between Starvation/Photo/Chemodynamic Therapies

Combining phototherapy with the cancer cell metabolic pathway altering strategies, that is, glucose starvation, would be a promising approach to accomplish high curative efficiency of cancer treatment. Accordingly, herein, we sought to construct a multifunctional biomimetic hybrid nanoreactor by fastening nanozyme AuNPs (glucose oxidase activity) and PtNPs (catalase and peroxidase activity) and photosensitizer Indocyanine green (ICG) onto the polydopamine (PDA) surface (ICG/Au/Pt@PDA-PEG) to attain superior cancer cell killing efficiency though win-win cooperation between starvation therapy, phototherapy, and chemodynamic therapy. The as-synthesized ICG/Au/Pt@PDA-PEG has shown excellent light-to-heat conversion (photothermal therapy) and reactive oxygen species generation (photodynamic therapy) properties upon laser irradiation and also red-shifted ICG absorption (from 780 to 800 nm) and enhanced its photostability. Further, the ICG/Au/Pt@PDA-PEG NRs have reduced the solution glucose concentration and slightly increased solution oxygen levels and also enhanced 3,3',5,5'-tetramethylbenzidine oxidation in the presence of glucose through a cascade of enzymatic activities. The in vitro results demonstrated that the ICG/Au/Pt@PDA-PEG NRs have superior therapeutic efficacy against cancer cells via the cooperative effect between starvation/photo/chemodynamic therapies and not much toxicity to normal cells.

Construction of Novel Nanocomposites (Cu-MOF/GOD@HA) for Chemodynamic Therapy

The emerging chemodynamic therapy (CDT) has received an extensive attention in recent years. However, the efficiency of CDT is influenced due to the limitation of H2O2 in tumor. In this study, we designed and synthesized a novel core-shell nanostructure, Cu-metal organic framework (Cu-MOF)/glucose oxidase (GOD)@hyaluronic acid (HA) (Cu-MOF/GOD@HA) for the purpose of improving CDT efficacy by increasing H2O2 concentration and cancer cell targeting. In this design, Cu-MOF act as a CDT agent and GOD carrier. Cu(II) in Cu-MOF are reduced to Cu(I) by GSH to obtain Cu(I)-MOF while GSH is depleted. The depletion of GSH reinforces the concentration of H2O2 in tumor to improve the efficiency of CDT. The resultant Cu(I)-MOF catalyze H2O2 to generate hydroxyl radicals (·OH) for CDT. GOD can catalyze glucose (Glu) to supply H2O2 for CDT enhancement. HA act as a targeting molecule to improve the targeting ability of Cu-MOF/GOD@HA to the tumor cells. In addition, after loading with GOD and coating with HA, the proportion of Cu(I) in Cu-MOF/GOD@HA is increased compared with the proportion of Cu(I) in Cu-MOF. This phenomenon may shorten the reactive time from Cu-MOF to Cu(I)-MOF. The CDT enhancement as a result of GOD and HA effects in Cu-MOF/GOD@HA was evidenced by in vitro cell and in vivo animal studies.

Cell membrane inspired nano-shell enabling long-acting Glucose Oxidase for Melanoma starvation therapy via microneedles-based percutaneous delivery

Rationale: Glucose oxidase (GOx) has gained tremendous research interest recently as a glucose-consuming enzyme for tumor starvation therapy, while its in vivo applications are strictly limited by rapid deactivation, as well as side effects of non-specific catalysis.

Methods: To address these issues, here we report a protective nano-shell to encapsule GOx for localized melanoma therapy delivered by dissolving microneedles (MNs). Inspired by cell membrane that separates and protects cell organelles and components from outside environment while selectively ingesting nutrition sources, we designed polydopamine (PDA)-structured nano-shell to allow free transportation of glucose for catalytic reaction, while impede the penetration of GOx, proteinase, and other GOx-deactivating macromolecules across the shell membrane.

Results: GOx was well protected in core layer with persistent catalytic activity for at least 6 d under various biological matrixes (e.g., PBS, serum, and cell lysate) and surviving different harsh conditions (e.g., acid/base treatments, and proteinase-induced degradation). Such long-acting nano-catalyst can be easily integrated into MNs as topical delivery carrier for effective glucose consumption in melanoma tissue, achieving significant tumor growth inhibition via starvation therapy with minimized side effects as compared to systemic administration.

Conclusion: This work provides an elegant platform for in vivo delivery of GOx, and our cell-mimicking nano-system can also be applied for other enzyme-based therapeutics.

Biodegradable cascade nanocatalysts enable tumor-microenvironment remodeling for controllable CO release and targeted/synergistic cancer nanotherapy

Gas therapy as an emerging therapeutic modality for cancer treatment is still facing critical challenges such as precise delivery and controllable release of therapeutic gas. Herein, we report a "tumor-microenvironment remodeling" strategy for in situ sustained release of CO gas and magnetic resonance imaging (MRI)-monitored targeted/synergistic cancer gas/starvation nanotherapy by engineering cascade biodegradable nanocatalyst. The nanocatalyst integrates the enzyme catalyst glucose oxidase (GOD) and H₂O₂-sensitive molecule manganese carbonyl (MnCO) entrapped biodegradable hollow mesoporous organosilica nanoparticles (HMONs). Especially, GOD is initially exploited as a gatekeeper, followed by surface engineering with arginine-glycine-aspartic acid (RGD) for specifically targeting α_vβ₃ integrin-overexpressed cancer cells. The GOD is dissociated under reduced pH to release the loaded MnCO, and sequentially produce gluconic acid and H₂O₂ to remodel the TME for facilitating the in situ generation of CO/Mn²⁺. As systematically demonstrated both at cellular level and in an animal tumor xenograft model, the engineered nanocatalyst achieves superior theranostics performance via combinatorial CO gas and starving-like nanotherapy. This work provides an effective strategy for augmenting CO-mediated antitumor efficacy by remodeling the tumor microenvironment.

Chemodynamic nanomaterials for cancer theranostics

It is of utmost urgency to achieve effective and safe anticancer treatment with the increasing mortality rate of cancer. Novel anticancer drugs and strategies need to be designed for enhanced therapeutic efficacy. Fenton- and Fenton-like reaction-based chemodynamic therapy (CDT) are new strategies to enhance anticancer efficacy due to their capacity to generate reactive oxygen species (ROS) and oxygen (O2). On the one hand, the generated ROS can damage the cancer cells directly. On the other hand, the generated O2 can relieve the hypoxic condition in the tumor microenvironment (TME) which hinders efficient photodynamic therapy, radiotherapy, etc. Therefore, CDT can be used together with many other therapeutic strategies for synergistically enhanced combination therapy. The antitumor applications of Fenton- and Fenton-like reaction-based nanomaterials will be discussed in this review, including: (iþ) producing abundant ROS in-situ to kill cancer cells directly, (ii) enhancing therapeutic efficiency indirectly by Fenton reaction-mediated combination therapy, (iii) diagnosis and monitoring of cancer therapy. These strategies exhibit the potential of CDT-based nanomaterials for efficient cancer therapy.

Inorganic nanomaterials with rapid clearance for biomedical applications

Inorganic nanomaterials that have inherently exceptional physicochemical properties (e.g., catalytic, optical, thermal, electrical, or magnetic performance) that can provide desirable functionality (e.g., drug delivery, diagnostics, imaging, or therapy) have considerable potential for application in the field of biomedicine. However, toxicity can be caused by the long-term, non-specific accumulation of these inorganic nanomaterials in healthy tissues, preventing their large-scale clinical utilization. Over the past several decades, the emergence of biodegradable and clearable inorganic nanomaterials has offered the potential to prevent such long-term toxicity. In addition, a comprehensive understanding of the design of such nanomaterials and their metabolic pathways within the body is essential for enabling the expansion of theranostic applications for various diseases and advancing clinical trials. Thus, it is of critical importance to develop biodegradable and clearable inorganic nanomaterials for biomedical applications. This review systematically summarizes the recent progress of biodegradable and clearable inorganic nanomaterials, particularly for application in cancer theranostics and other disease therapies. The future prospects and opportunities in this rapidly growing biomedical field are also discussed. We believe that this timely and comprehensive review will stimulate and guide additional in-depth studies in the area of inorganic nanomedicine, as rapid in vivo clearance and degradation is likely to be a prerequisite for the future clinical translation of inorganic nanomaterials with unique properties and functionality.

Cyclic reactions-mediated self-supply of H2O2 and O2 for cooperative chemodynamic/starvation cancer therapy

Hydroxyl radical (·OH)-mediated chemodynamic therapy (CDT) and glucose oxidase (GOx)-based starvation therapy (ST) are two emerging antitumor strategies, limited by acid/H₂O₂ deficiency and tumor hypoxia, respectively. Herein, we developed a liposomal nanoplatform co-delivering Fe(OH)₃-doped CaO₂ nanocomposites and GOx molecules for synergistic CDT/ST with a complementary effect. Based on Fenton reactions initiated by iron ions, CaO₂-supplied H₂O₂ could not only generate ·OH for H₂O₂-sufficient CDT, but also produce O₂ to promote the catalytic efficiency of GOx under hypoxia. In return, the enhanced ST generated gluconic acid and H₂O₂, further amplifying CDT. Through in vitro and in vivo experiments, we demonstrated that such a mutually reinforced modality based on the cyclic Fenton/starvation reactions provided a novel and potent anticancer mechanism for the effective treatment of hypoxic cancers.

Self-preparation system using glucose oxidase-inspired nitroreductase amplification for cascade-responsive drug release and multidrug resistance reversion

Early antitumor therapy is an important determinant of survival in patients with cancer. Utilization of specific pathological states, such as hypoxia, greatly promotes the development of intelligent drug delivery systems (DDSs) for targeted antitumor therapy. However, a slight decrease in oxygen levels in early-stage tumors is not sufficient to trigger hypoxia-responsive drug release. Nitroreductase (NTR) is overexpressed in bioreductive hypoxic cancers, and its expression level has been verified to be directly related to hypoxic status. Herein, using glucose oxidase (GOx) as an O₂-consuming agent to exacerbate hypoxia, a cascade strategy of GOx-induced overexpression of NTR and amplified NTR-catalyzed release was proposed for early antitumor therapy. Briefly, NTR-sensitive p-nitrobenzyl chloroformate (PNZ-Cl) was adopted to conjugate with the polysaccharide chitosan (CS) and self-assemble into CS-PNZ-Cl micelles. These polymer micelles possess the dual abilities to specifically immobilize GOx and load mitoxantrone (MIT) to form the NTR-responsive nanocascade reactor GOx/MIT@CS-PNZ-Cl. First, as a "key", tumor hypoxia triggers the initial release of GOx, which serves as the O₂-consuming agent when catalyzing its reaction with glucose, which is accompanied by H₂O₂ production. Depleted oxygen levels facilitate the expression of NTR, which in turn amplifies the capacity of the nanocascade reactor to decompose into secondary micelles for enhanced intratumoral permeation. GOx-inspired NTR amplification further elicits MIT release, realizing a synergistic "domino effect" cascade. In addition, upregulated H₂O₂ has been shown to effectively reverse GSH-mediated MIT resistance, reaching the superior tumor inhibition rate of 93.08%. This GOx-based NTR-responsive nanocascade reactor provides amplification of the bioreductive hypoxic tumor microenvironment for early antitumor therapy.

Liposome-Coated Arsenic-Manganese Complex for Magnetic Resonance Imaging-Guided Synergistic Therapy Against Carcinoma

Purpose

A liposome-coated arsenic-manganese complex, denoted as LP@MnAs_x was constructed for the targeted delivery of arsenic trioxide (ATO) against carcinoma.

Methods

Arsenite, the prodrug of ATO, was encapsulated within a liposome via electrostatic interaction with the manganese ions. The as-prepared material was characterized with dynamic light scattering and transmission electron microscopy. The entrapment efficiency and drug loading of arsenic in the carrier were measured using inductively coupled plasma spectrometry. The in vitro release of arsenic was evaluated by using the dialysis bag method. Furthermore, the Fenton-like activity and in vitro cytodynamics research of LP@MnAs_x were monitored in this work. And the cellular uptake study was used to investigate the in vitro entry mechanism. Furthermore, the cytotoxicity, cell apoptosis and cell cycle study were performed to evaluate the tumor-killing efficiency. Also, the pharmacokinetic and antitumor studies were investigated in HepG2 tumor-bearing nude mice.

Results

The as-prepared LP@MnAs_x possessed a spherical morphology, uniformly distributed hydrodynamic diameter, and excellent drug-loading efficiency. LP@MnAs_x displayed robust stability and sustained-release profile under physiological environments. LP@MnAs_x could degrade with high sensitivity to the pH variation in the tumor microenvironment. As such, this could lead to a burst release profile of Mn²⁺ and arsenite to achieve a synergistic therapy of chemodynamic therapy and chemotherapy. When compared to the carrier-free arsenate, in vitro experiments revealed that LP@MnAs_x exhibited enhanced cellular uptake and tumor-killing efficiency. LP@MnAs_x also demonstrated significantly enhanced tumor-specific in vivo distribution of arsenic, prolonged systemic circulation lifetime, and increased accumulation at the tumor site.

Conclusion

Based on the experimental results, LP@MnAs_x is an ideal arsenic-based nanodelivery system, whereby it can improve the non-specific distribution of NaAsO₂ in vivo. Thus, this work can expand the research and application of arsenic trioxide against solid tumors.

Zeolitic Imidazolate Framework Platform for Combinational Starvation Therapy and Oxygen Self-Sufficient Photodynamic Therapy against a Hypoxia Tumor

The antitumor efficacy of photodynamic therapy (PDT) is greatly impeded by the nonspecific targeting of photosensitizers and limited oxygen supply in hypoxic tumors. Aiming to overcome the problem, a dual-locked porphyrin/enzyme-loading zeolitic imidazolate framework (ZIF) nanoplatform was constructed for starvation therapy and O₂ self-sufficient PDT. The fluorescence recovery and PDT of photosensitizers could be cooperatively triggered by dual pathological parameters, the low pH and overexpressed GSH in tumor tissues, which makes the PDT process conduct precisely in a tumor microenvironment. The cascade catalysis of glucose oxidase and catalase promotes the nanoplatform dissociation, inhibits the energy supply of tumors (starvation therapy), and provides enough O₂ to ameliorate the hypoxia and enhance PDT efficacy. In vitro and in vivo studies were performed to confirm the high antitumor efficacy of the porphyrin/enzyme-loading ZIF nanoplatform. Thus, this work offers a path for precise and efficient PDT-based combination therapy against a hypoxia tumor.

Skillfully collaborating chemosynthesis with GOx-enabled tumor survival microenvironment deteriorating strategy for amplified chemotherapy and enhanced tumor ablation

The satisfactory efficient tumor treatment and complete tumor ablation using a mono-therapeutic approach are limited owing to the tumor complexity, diversity, heterogeneity and the multiple pathways involved in tumor pathogenesis. Herein, novel, intelligent and tumor microenvironment (TME)-responsive biotin/R8 peptide co-modified nanocarriers (BRNC) loading paclitaxel (PTX)/glucose oxidase (GOx) were constructed. GOx could catalyze the oxidation of intracellular glucose to gluconic acid and poisonous H2O2 to cause the deterioration of the tumor survival microenvironment, simultaneously achieving starvation and oxidation therapy. The acidic amplification during the GOx-mediated oxidation progress could in turn accelerate the cleavage of the acid-degradable hydrazone bond, promoting the deep penetration of nanocarriers into tumors. Even better, the aforementioned two aspects further increased the tumors' sensitivity to chemotherapeutic agents. Both in vitro and in vivo investigations indicated that the co-administration of GOx-BRNC and PTX-BRNC can remarkably improve the therapeutic efficacy and reduce side effects through the high-specific tumor targeting multimodal synergistic starvation/oxidation/chemotherapy, which would be a promising strategy for the next generation cancer therapy.

Biomimetic nanoreactor for targeted cancer starvation therapy and cascade amplificated chemotherapy

Consuming glucose by glucose oxidase (GOx) has attracted great interest in cancer starvation therapy, but the therapeutic effect is severely limited by the tumor hypoxia environment. Herein, to overcome such limitation, cancer cell membranes disguised biomimetic nanoreactors were elaborately established for synergetic cancer starvation therapy and cascade amplificated hypoxia activated chemotherapy. Via a metallothionein-like self-assembly and infiltration approach, GOx and hypoxia activated prodrug banoxantrone (AQ4N) were efficiently loaded into metal-organic framework ZIF-8 nanocarriers to yield nanoreactor AQ4N/GOx@ZIF-8. Subsequently, the biomimetic nanoreactor (AQ4N/GOx@ZIF-8@CM) was obtained by camouflaging the nanoreactor with cancer cell membrane, which endowed the biomimetic nanoreactor homotypic targeting, immune escape and prolonged blood circulation features. Once targeted accumulating into tumor sites, the acid environment triggered the decomposition of ZIF-8, then encapsulated GOx and AQ4N were released. GOx would rapidly exhaust endogenous glucose and O₂ to shut off the energy supply of tumor cells for starvation treatment. Furthermore, the aggravated tumor intracellular hypoxia environment would activate the cytotoxicity of AQ4N for chemotherapy. In vitro and in vivo results demonstrated that the designed biomimetic nanoreactor exhibited negligible systemic toxicity, besides, the combination of starvation therapy and cascade amplified hypoxia activated chemotherapy significantly inhibited the tumor growth and improved the therapeutic efficacy.

Bioactive metal-containing nanomaterials for ferroptotic cancer therapy

The clinical performance of the current cancer therapies is still far from satisfactory. The emerging ferroptosis-driven therapy strategies reignite the hope of chemotherapy in tumor treatment due to their incredible tumor suppression. Among ferroptosis-based cancer therapies, metal elements have attracted remarkable attention due to their inherent physicochemical properties in inducing ferroptosis of tumor cells quickly and strongly without complex cellular signal transduction. Although the discovery and applications of ferroptosis for tumor treatment have been discussed in many reviews, the unique advantages of metal-containing nanomaterials interfering ferroptotic cancer therapies (MIFCT) have seldom been mentioned. Here, we outline the latest advances of MIFCT comprehensively. Firstly, the functions of different kinds of metal elements or their ions are introduced to illustrate their advantages in MIFCT. Secondly, the emerging metal-containing nanomaterials that are designed to achieve ferroptosis-driven therapy are overviewed, including their ability to boost the Fenton or Fenton-like reaction for reactive oxygen species generation, act as hydrogen peroxide self-providers, damage the reducing system, and disturb cellular communication. Moreover, metal-containing nanomaterials with external energy conversion features for MIFCT are discussed. Finally, the future expectations and challenges of MIFCT for clinical cancer therapy are spotlighted.

Manganese-Dioxide-Coating-Instructed Plasmonic Modulation of Gold Nanorods for Activatable Duplex-Imaging-Guided NIR-II Photothermal-Chemodynamic Therapy

Nanotheranostic agents of gold nanomaterials in the second near-infrared (NIR-II) window have attracted significant attention in cancer management, owing to the reduced background signal and deeper penetration depth in tissues. However, it is still challenging to modulate the localized surface plasmon resonance (LSPR) of gold nanomaterials from the first near-infrared (NIR-I) to NIR-II region. Herein, a plasmonic modulation strategy of gold nanorods (GNRs) through manganese dioxide coating is developed for NIR-II photoacoustic/magnetic resonance (MR) duplex-imaging-guided NIR-II photothermal chemodynamic therapy. GNRs are coated with silica dioxide (SiO2 ) and then covered with magnesium dioxide (MnO2 ) to obtain the final product of GNR@SiO2 @MnO2 (denoted as GSM). The LSPR peak of GNRs could be tuned by adjusting the thickness of the MnO2 layer. Theoretical simulations reveal that this plasmonic modulation is mainly due to the change of refraction index around the GNRs after coating with the MnO2 layer. Additionally, the MnO2 layer is demonstrated to degrade into Mn2+ ions in response to peroxide and acidic protons in the tumor microenvironment, which allows for MR imaging and chemodynamic therapy. This plasmonic modulation strategy can be adapted to other metal nanomaterials and the construction of a new class of NIR-II nanotheranostics.

Hypoxia modulation by dual-drug nanoparticles for enhanced synergistic sonodynamic and starvation therapy

BACKGROUND

Sonodynamic therapy (SDT) is an emerging non-invasive therapeutic technique. SDT-based cancer therapy strategies are presently underway, and it may be perceived as a promising approach to improve the efficiency of anti-cancer treatment. In this work, multifunctional theranostic nanoparticles (NPs) were synthesized for synergistic starvation therapy and SDT by loading glucose oxidase (GOx, termed G) and 5,10,15,20-tetrakis (4-chlorophenyl) porphyrin) Cl (T (p-Cl) PPMnCl, termed PMnC) in Poly (lactic-co-glycolic) acid (PLGA) NPs (designated as MG@P NPs).

RESULTS

On account of the peroxidase-like activity of PMnC, MG@P NPs can catalyze hydrogen peroxide (H2O2) in tumor regions to produce oxygen (O2), thus enhancing synergistic therapeutic effects by accelerating the decomposition of glucose and promoting the production of cytotoxic singlet oxygen (1O2) induced by ultrasound (US) irradiation. Furthermore, the NPs can also serve as excellent photoacoustic (PA)/magnetic resonance (MR) imaging contrast agents, effectuating imaging-guided cancer treatment.

CONCLUSION

Multifunctional MG@P NPs can effectuate the synergistic amplification effect of cancer starvation therapy and SDT by hypoxia modulation, and act as contrast agents to enhance MR/PA dual-modal imaging. Consequently, MG@P NPs might be a promising nano-platform for highly efficient cancer theranostics.

Artificial Bioaugmentation of Biomacromolecules and Living Organisms for Biomedical Applications

The synergistic union of nanomaterials with biomaterials has revolutionized synthetic chemistry, enabling the creation of nanomaterial-based biohybrids with distinct properties for biomedical applications. This class of materials has drawn significant scientific interest from the perspective of functional extension via controllable coupling of synthetic and biomaterial components, resulting in enhancement of the chemical, physical, and biological properties of the obtained biohybrids. In this review, we highlight the forefront materials for the combination with biomacromolecules and living organisms and their advantageous properties as well as recent advances in the rational design and synthesis of artificial biohybrids. We further illustrate the incredible diversity of biomedical applications stemming from artificially bioaugmented characteristics of the nanomaterial-based biohybrids. Eventually, we aim to inspire scientists with the application horizons of the exciting field of synthetic augmented biohybrids.

A Three-in-one ZIFs-Derived CuCo(O)/GOx@PCNs Hybrid Cascade Nanozyme for Immunotherapy/Enhanced Starvation/Photothermal Therapy

Glucose oxidase (GOx) is regarded as an ideal endogenous natural enzyme for tumor starvation therapy and photothermal therapy (PTT) is a promising strategy for the ablation of primary tumor. In this work, Cu-doped cobalt oxide and porous carbon nanocomposites (CuCo(O)@PCNs) were synthesized from double-layered ZIF-8@ZIF-67 and GOx was loaded in the porous carbon to form a CuCo(O)/GOx@PCNs hybrid nanozyme. CuCo(O) was characterized as the Cu_0.3Co_2.7O₄ phase through X-ray diffraction analysis and it can react with H₂O₂ to generate O₂ and alleviate tumor hypoxia, resulting in the recovered enzymatic activity of GOx and the enhanced starvation therapy. The porous nanocarbon can ablate the primary tumor because of its high photothermal conversion efficiency of 40.04%. The three-in-one functions of oxygen supply, glucose consumption, and photothermal conversion were realized in the ZIFs-derived CuCo(O)/GOx@PCNs nanozyme and the starvation therapy effect was improved by PTT and oxygen supplement. Furthermore, the inhibition effect of CuCo(O)/GOx@PCNs on metastatic tumor is similar to combined therapy of the nanozyme and the immune checkpoint-blocking antibody, α-PD-1. The related antitumor immune mechanism was studied through the analysis of immune-related proinflammatory cytokines and the activated T cells. This work may provide new ideas for the development and application of the ZIFs-derived hybrid nanozyme in tumor therapy and the CuCo(O)/GOx@PCNs nanozyme may be a promising alternative to immune checkpoint inhibitors.

Functionalized graphene oxide in situ initiated ring-opening polymerization for highly sensitive sensing of cytokeratin-19 fragment

Improving the sensitivity of detection is crucial to monitor biomarker, assess toxicity, and track therapeutic agent. Herein, a sensitivity-improved immunosensor is reported for the first time via functionalized graphene oxide (GO) and a "grafting-to" ring-opening polymerization (ROP) dual signal amplification strategy. Through the ROP reaction using 2-[(4-ferrocenylbutoxy)methyl] oxirane (FcEpo) as the monomer, lots of electroactive tags are linked in situ from multiple initiation sites on the GO surface modified with ethanol amine (GO-ETA), thereby achieving high sensitivity even in the case of trace amounts of tumor markers. The utmost important factor for achieving this high sensitivity is to select functionalized GO as the initiator that contains a large number of repeated hydroxyl functional groups so as to trigger additional ROP reaction. Under the optimal conditions, the high sensitivity and applicability is demonstrated by the use of GO-ETA-mediated ROP-based immunosensor to detect non-small cell lung cancer (NSCLC)-specific biomarker down to 72.58 ag/mL (equivalent to ~6 molecules in a 5 μL sample). Furthermore, the satisfactory results for the determination of biomarkers in clinical serum samples highlighted that this immunosensor holds a huge potential in practical clinical application. This work described an electrochemical immunosensor for ultrasensitive detection of CYFRA 21-1 via the functionalized graphene oxide (GO) and a "grafting-to" ring-opening polymerization (ROP) dual signal amplification strategy, which hold the merits of high sensitivity, applicability, selectivity, efficiency, easy operation and environmental friendliness.

Construction of Enzyme Nanoreactors to Enable Tumor Microenvironment Modulation and Enhanced Cancer Treatment

Enzymes play pivotal roles in regulating and maintaining the normal functions of all living systems, and some of them are extensively employed for diagnosis and treatment of diverse diseases. More recently, several kinds of enzymes with unique catalytic activities have been found to be promising options to directly suppress tumor growth and/or augment the therapeutic efficacy of other treatments by modulating the hostile tumor microenvironment (TME), which is reported to negatively impair the therapeutic efficacy of different cancer treatments. In this review, first a summary is presented on the chemical approaches utilized for the construction of distinct enzyme nanoreactors with well-retained catalytic performance and reduced immunogenicity. Then, the utilization of such enzyme nanoreactors in attenuating tumor hypoxia, modulating extracellular matrix, and amplifying tumor oxidative stress is discussed in depth. Afterward, some perspectives are presented on the future development of such enzyme nanoreactors in TME modulation and enhanced cancer treatment.

Size controlled fabrication of enzyme encapsulated amorphous calcium phosphate nanoparticle and its intracellular biosensing application

Inorganic-enzyme composites have been widely used for applications in catalysis and analytical science. Amorphous calcium phosphate, as a biocompatible material, can form open hydrated structure to encapsulate and protect enzymes. So far, there have been few progress on size-adjustable amorphous calcium phosphate nanoparticles since the diameter controllability is limited by its natural aggregation characteristics. By co-precipitation and nano-channel extrusion, we developed enzyme-loaded amorphous calcium phosphate nanoparticles with adjustable diameters. These enzyme-loaded particles showed high thermal and chemical stability as well as biocompatibility. The nano-sized enzyme-loaded particles can further expand their application fields and be used as intracellular enzyme probes. Delivering glucose oxidase enzyme by amorphous calcium phosphate nanoparticles enables fluorescent monitoring of glucose levels in living cells, which can be used to study the metabolism rates of cancer cells and normal cells. The nano-channel extrusion method can also be used as a template to encapsulate different kinds of enzymes to expand catalysis and biosensing applications.

Mn-DNA coordination of nanoparticles for efficient chemodynamic therapy

A kind of nanoparticle is developed for highly efficient chemodynamic therapy that only relies on the endogenous H2O2 of cancer cells. For this nanoparticle, high-molecular-weight DNA is used as the biocompatible carrier to load abundant Mn2+ ions. Therefore, the resultant Mn-DNA coordination nanoparticles can efficiently deliver and sensitively release Mn2+ in cancer cells, resulting in high toxicity through the Fenton-like reaction.

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.