Rapid Decomposition and Catalytic Cascade Nanoplatforms Based on Enzymes and Mn-Etched Dendritic Mesoporous Silicon for MRI-Guided Synergistic Therapy

Hyaluronic Acid-Modified Spherical MgO2/Pd Nanocomposites Exhibit Superior Antitumor Effect through Tumor Microenvironment-Responsive Ferroptosis Induction and Photothermal Therapy

Metal peroxide nanomaterials as efficient hydrogen peroxide (H2O2) self-supplying agents have attracted the attention of researchers for antitumor treatment. However, relying solely on metal peroxides to provide H2O2 is undoubtedly insufficient to achieve optimal antitumor effects. Herein, we construct novel hyaluronic acid (HA)-modified nanocomposites (MgO2/Pd@HA NCs) formed by decorating palladium nanoparticles (Pd NPs) onto the surfaces of a magnesium peroxide (MgO2) nanoflower as a highly effective nanoplatform for the tumor microenvironment (TME)-responsive induction of ferroptosis in tumor cells and tumor photothermal therapy (PTT). MgO2/Pd@HA NC could be well endocytosed into tumor cells with CD44 expression depending on the specific recognition of HA with CD44, and then, the nanocomposites can be rapidly decomposed in mild acid and hyaluronidase overexpressed TME, and plenty of H2O2 was released. Simultaneously, Pd NPs catalyze self-supplied H2O2 to generate abundant hydroxyl radicals (•OH) and catalyze glutathione (GSH) into glutathione disulfide owing to its peroxidase and glutathione oxidase mimic enzyme activities, while the abundant •OH could also consume GSH in tumor cells and disturb the defense pathways of ferroptosis leading to the accumulation of lipid peroxidation and resulting in the occurrence of ferroptosis. Additionally, the superior photothermal conversion performance of Pd NPs in near-infrared II could also be used for PTT, synergistically cooperating with nanocomposite-induced ferroptosis for tumor inhibition. Consequently, the successfully prepared TME-responsive MgO2/Pd@HA NCs exhibited marked antitumor effect without obvious biotoxicity, contributing to thoroughly explore the nanocomposites as a novel and promising treatment for tumor therapy.

Proton Sponge Nanocomposites for Synergistic Tumor Elimination via Autophagy Inhibition-Promoted Cell Apoptosis and Macrophage Repolarization-Enhanced Immune Response

Cytoprotective autophagy and an immunosuppressive tumor microenvironment (TME) are two positive promoters for tumor proliferation and metastasis that severely hinder therapeutic efficacy. Inhibiting autophagy and reconstructing TME toward macrophage activation simultaneously are of great promise for effective tumor elimination, yet are still a huge challenge. Herein, a kind of dendrimer-based proton sponge nanocomposites was designed and constructed for tumor chemo/chemodynamic/immunotherapy through autophagy inhibition-promoted cell apoptosis and macrophage repolarization-enhanced immune response. These obtained nanocomposites contain a proton sponge G5AcP dendrimer, a Fenton-like agent Cu(II), and chemical drug doxorubicin (DOX). When accumulated in tumor regions, G5AcP can act as an immunomodulator to realize deacidification-promoted macrophage repolarization toward antitumoral type, which then secretes inflammatory cytokines to activate T cells. They also regulate intracellular lysosomal pH to inhibit cytoprotective autophagy. The released Cu(II) and DOX can induce aggravated damage through a Fenton-like reaction and chemotherapeutic effect in this autophagy-inhibition condition. Tumor-associated antigens are released from these dying tumor cells to promote the maturity of dendritic cells, further activating T cells. Effective tumor elimination can be achieved by this dendrimer-based therapeutic strategy, providing significant guidance for the design of a promising antitumor nanomedicine.

Engineered photonic near-infrared light activated photothermal theranostic nanovaccine induced targeted remodeling of tumor microenvironment

Tumor recurrence, which happens as a result of persisting tumor cells and minor lesions after treatments like surgery and chemotherapy, is a major problem in oncology. Herein, a strategy to combat this issue by utilize a theranostic nanovaccine composed of photonic HCuS. This nanovaccine aims to eradicate cancer cells and their traces while also preventing tumor recurrence via optimizing the photothermal immune impact. Successful membrane targeting allows for the introduction of new therapeutic agents into the tumor cells. Together with co-encapsulated Toll-Like Receptors (TLR7/8) agonist R848 for activating T cells and maturing DCs, the combined effects of HCuS and ICG function as photothermal agents that generate heat in the presence of NIR light. Photothermal-mediated immunotherapy with therapeutic modalities proved successful in killing tumor cells. By activating the immune system, this new photonic nanovaccine greatly increases immunogenic cell death (ICD), kills tumor cells, and prevents their recurrence.

Bimetallic nanoplatform for synergistic sonodynamic-calcium overload therapy utilizing self-supplied hydrogen peroxide and relieved hypoxia

Sonodynamic therapy (SDT) has emerged as a potential alternative to traditional cancer treatments as it offers deep cellular penetration and reduced invasivity. Sonosensitizers generate reactive oxygen species (ROS) under ultrasound activation, focusing the ultrasound energy on malignant sites located deep in tissues and causing cell apoptosis and necrosis. However, due to tumor hypoxia and the limited levels of intracellular endogenous hydrogen peroxide (H2O2 is a fundamental species for supplying oxygen via catalase activity), SDT efficacy is still insufficient. In this study, a bimetallic and multifunctional system (Fe3O4-TAPP@PVP-CaO2) was prepared by using ferrosoferric oxide (Fe3O4) as a carrier loaded with 5,10,15,20-tetrakis(4-aminophenyl), porphyrin (TAPP), that was then coated with polyvinyl pyrrolidone (PVP) and calcium peroxide (CaO2). The CaO2 layer elevated the levels of H2O2 and Ca2+ in the tumor microenvironment when exposed to intracellular acidity, providing essential elements for oxygen generation. Intracellular hypoxia was alleviated via the catalase-like activity of Fe3O4 inducing calcium overload. Under ultrasonic irradiation, SDT generated toxic reactive oxygen species (ROS, singlet oxygen) and activated calcium influx through acoustic cavitation. Meanwhile, calcium overload therapy efficiently induced cell apoptosis at the moment of uncontrollable cellular accumulation of Ca2+. In addition, we modified the PVP on the surface to make it more stable. This study presents a bimetallic nanoplatform that can efficiently induce cancer cell death by synergistic sonodynamic-calcium overload therapy via modulation of O2/ROS/Ca2+ species, indicating its potential for multi-modality cancer therapy.

Nanoreactor-based catalytic systems for therapeutic applications: Principles, strategies, and challenges

Inspired by natural catalytic compartments, various synthetic compartments that seclude catalytic reactions have been developed to understand complex multistep biosynthetic pathways, bestow therapeutic effects, or extend biosynthetic pathways in living cells. These emerging nanoreactors possessed many advantages over conventional biomedicine, such as good catalytic activity, specificity, and sustainability. In the past decade, a great number of efficient catalytic systems based on diverse nanoreactors (polymer vesicles, liposome, polymer micelles, inorganic-organic hybrid materials, MOFs, etc.) have been designed and employed to initiate in situ catalyzed chemical reactions for therapy. This review aims to present the recent progress in the development of catalytic systems based on nanoreactors for therapeutic applications, with a special emphasis on the principles and design strategies. Besides, the key components of nanoreactor-based catalytic systems, including nanocarriers, triggers or energy inputs, and products, are respectively introduced and discussed in detail. Challenges and prospects in the fabrication of therapeutic catalytic nanoreactors are also discussed as a conclusion to this review. We believe that catalytic nanoreactors will play an increasingly important role in modern biomedicine, with improved therapeutic performance and minimal side effects.

Cascade strategy for glucose oxidase-based synergistic cancer therapy using nanomaterials

Nanomaterial-based cancer therapy faces significant limitations due to the complex nature of the tumor microenvironment (TME). Starvation therapy is an emerging therapeutic approach that targets tumor cell metabolism using glucose oxidase (GOx). Importantly, it can provide a material or environmental foundation for other diverse therapeutic methods by manipulating the properties of the TME, such as acidity, hydrogen peroxide (H2O2) levels, and hypoxia degree. In recent years, this cascade strategy has been extensively applied in nanoplatforms for ongoing synergetic therapy and still holds undeniable potential. However, only a few review articles comprehensively elucidate the rational designs of nanoplatforms for synergetic therapeutic regimens revolving around the conception of the cascade strategy. Therefore, this review focuses on innovative cascade strategies for GOx-based synergetic therapy from representative paradigms to state-of-the-art reports to provide an instructive, comprehensive, and insightful reference for readers. Thereafter, we discuss the remaining challenges and offer a critical perspective on the further advancement of GOx-facilitated cancer treatment toward clinical translation.

Three Strategies in Engineering Nanomedicines for Tumor Microenvironment-Enabled Phototherapy

Canonical phototherapeutics have several limitations, including a lack of tumor selectivity, nondiscriminatory phototoxicity, and tumor hypoxia aggravation. The tumor microenvironment (TME) is characterized by hypoxia, acidic pH, and high levels of H2 O2 , GSH, and proteases. To overcome the shortcomings of canonical phototherapy and achieve optimal theranostic effects with minimal side effects, unique TME characteristics are employed in the development of phototherapeutic nanomedicines. In this review, the effectiveness of three strategies for developing advanced phototherapeutics based on various TME characteristics is examined. The first strategy involves targeted delivery of phototherapeutics to tumors with the assistance of TME-induced nanoparticle disassembly or surface modification. The second strategy involves near-infrared absorption increase-induced phototherapy activation triggered by TME factors. The third strategy involves enhancing therapeutic efficacy by ameliorating TME. The functionalities, working principles, and significance of the three strategies for various applications are highlighted. Finally, possible challenges and future perspectives for further development are discussed.

Hydrazide/Metal/Indocyanine Green Coordinated Nanoplatform for Potentiating Reciprocal Ferroptosis and Immunity against Melanoma

Ferroptosis holds great potential in cancer treatment, but its efficacy is severely limited by a low Fenton reaction efficacy. Meanwhile, the interactive relationship between Ferroptosis and the PD-1 blockade is still vague. Herein, a hydrazide/Cu/Fe/indocyanine green coordinated nanoplatform (TCFI) is constructed by a hydrazide-metal-sulfonate coordination process. The TCFI nanoplatform exhibits Fenton-/catalase-/glutathione oxidase-like triple activities and accordingly can trigger lipid peroxidation, relieve hypoxia, and downregulate the glutathione/glutathione peroxidase 4 axis, thus achieving positively and negatively dually enhanced Ferroptosis in B16F10 cancer cells. Under near-infrared laser irradiation, the TCFI nanoplatform induces robust immunogenic cancer cell death by elevating the intracellular reactive oxygen species level through synergistic photodynamic therapy/Ferroptosis, which significantly potentiates CD8+ T cell infiltration into tumors and interferon-γ secretion. Moreover, upregulated interferon-γ efficiently inhibits system xc- activity and sensitizes cancer cells to Ferroptosis. Interestingly, the PD-1 blockade may strengthen the reciprocal process. The combination of the TCFI nanoplatform and αPD-1 can eliminate primary tumors and inhibit distant tumor growth, lung metastasis, and tumor recurrence. This study presents a simple and novel coordination strategy to fabricate tumor microenvironment-responsive nanodrugs and highlights the enhancement effect of photodynamic therapy on reciprocal Ferroptosis and antitumor immunity.

Stimuli-Responsive Double Single-Atom Catalysts for Parallel Catalytic Therapy

Tumor microenvironment (TME)-induced nanocatalytic therapy is a trending strategy for tumor-targeting therapy, but the low catalytic efficiency remains to limit its therapeutic effect. The single-atom catalysts (SACs) appear as a novel type of nanozymes that possesses incredible catalytic activity. Here, we developed PEGylated manganese/iron-based SACs (Mn/Fe PSACs) by coordinating single-atom Mn/Fe to nitrogen atoms in hollow zeolitic imidazolate frameworks (ZIFs). Mn/Fe PSACs catalyze cellular hydrogen peroxide (H2O2) converting to hydroxyl radical (•OH) through a Fenton-like reaction; it also enhances the decomposition of H2O2 to O2 that continuously converts to cytotoxic superoxide ion (•O2-) via oxidase-like activity. Mn/Fe PSACs can reduce the depletion of reactive oxygen species (ROS) by consuming glutathione (GSH). Here, we demonstrated the Mn/Fe PSACs-mediated synergistic antitumor efficacy among in vitro and in vivo experiments. This study proposes new promising single-atom nanozymes with highly efficient biocatalytic sites and synergistic therapeutic effects, which will give birth to abundant inspirations in ROS-related biological applications in broad biomedical fields.

Repolarizing tumor-associated macrophages by layered double hydroxide-based deacidification agent for tumor chemodynamic therapy and immunotherapy

Tumor-associated macrophages (TAMs)-mediated immunotherapy has attracted extensive attention in tumor elimination. However, the acidic tumor microenvironment (TME) severely limits the phenotype of TAMs to pro-tumoral M2 state, suppressing immune response efficacy against tumors. Herein, novel poly(acrylic acid) (PAA)-coated, doxorubicin (DOX)-loaded layered double hydroxide (LDH) nanosheets (NSs) were developed as deacidification agent to repolarize TAMs from pro-tumoral M2 to anti-tumoral M1 phenotype for tumor elimination through combined chemodynamic therapy and immunotherapy. When located in tumor regions, LDH-PAA@DOX NSs display good deacidification capacity to neutralize acidic TME, achieving the repolarization of TAMs to M1 phenotype and further activating CD8⁺ T cells. During the deacidification process, these NSs are acid-responsive and degrade to release Fe³⁺ and DOX. The former can be reduced to Fe²⁺ by intracellular glutathione, meanwhile disrupting the antioxidant defense system of tumor cells. The latter can damage tumor cells directly and further stimulate the production of hydrogen peroxide, providing abundant substrate for the Fenton reaction. Toxic hydroxyl radical is excessively produced through Fe²⁺-mediated Fenton reaction to cause intratumoral oxidative stress. In vivo data revealed that significant tumor elimination can be achieved under LDH-PAA@DOX treatment. This work not only provides a promising paradigm for neutralizing acidic TME using deacidification agent but also highlights the effectiveness of combined chemodynamic therapy and immunotherapy in tumor treatment.

Nanoparticles for cancer therapy: a review of influencing factors and evaluation methods for biosafety

Nanoparticles are widely used in the biomedical field for diagnostic and therapeutic purposes due to their small size, high carrier capacity, and ease of modification, which enable selective targeting and as contrast agents. Over the past decades, more and more nanoparticles have received regulatory approval to enter the clinic, more nanoparticles have shown potential for clinical translation, and humans have increasing access to them. However, nanoparticles have a high potential to cause unpredictable adverse effects on human organs, tissues, and cells due to their unique physicochemical properties and interactions with DNA, lipids, cells, tissues, proteins, and biological fluids. Currently, issues, such as nanoparticle side effects and toxicity, remain controversial, and these pitfalls must be fully considered prior to their application to body systems. Therefore, it is particularly urgent and important to assess the safety of nanoparticles acting in living organisms. In this paper, we review the important factors influencing the biosafety of nanoparticles in terms of their properties, and introduce common methods to summarize the biosafety evaluation of nanoparticles through in vitro and in body systems.

GSH-Responsive Organosilica Hybrid Nanosystem as a Cascade Promoter for Enhanced Starvation and Chemodynamic Therapy

Glucose oxidase (GOD)-mediated starvation therapy (ST) that causes intratumoral glucose depletion is a promising strategy for tumor treatment. However, the ultimate efficacy is inevitably limited by tumor hypoxia, as oxygen is a key component in the consumption of glucose by GOD. In this study, a kind of glutathione (GSH)-responsive organosilica hybrid micelles loaded with Mn₃ O₄ and GOD (denoted as Mn₃ O₄ @PDOMs-GOD) is ingeniously designed for enhanced ST and chemodynamic therapy (CDT). Specifically, the internalized Mn₃ O₄ @PDOMs-GOD in tumor cells consumes intracellular glucose and oxygen (O₂ ) under the catalysis of GOD to generate hydrogen peroxide (H₂ O₂ ), which is subsequently decomposed by Mn₃ O₄ to liberate O₂ . This cyclically regenerated O₂ will form a virtuous cycle of O₂ and H₂ O₂ compensation to enhance the ST outcome. Meanwhile, Mn₃ O₄ can oxidize and deplete the overexpressed GSH in the tumor microenvironment (TME) to release Mn²⁺ , which then catalyzes H₂ O₂ into highly toxic hydroxyl radicals (·OH) to accomplish chemodynamic therapy (CDT). Both in vitro and in vivo experiment results demonstrate the significant antitumor efficacy of Mn₃ O₄ @PDOMs-GOD by the cooperatively enhanced ST and CDT, suggesting the feasibility to develop promising therapeutic platforms with higher treatment efficacies.

Combining Cobalt Ferrite Nanozymes with a Natural Enzyme to Reshape the Tumor Microenvironment for Boosted Cascade Enzyme-Like Activities

Nanozymes with the merits of effective enzyme-mimic activities, tunable catalytic properties, pH/temperature tolerance, and high stability have been consumingly researched for nanocatalytic therapy. Herein, the union nanozymes and a natural enzyme nanoplatform (DMSN@CoFe₂O₄/GOD-PCM) are elaborately designed by simply depositing an ultrasmall cobalt ferrite (CoFe₂O₄) bimetallic oxide nanozyme and natural glucose oxidase (GOD) that are loaded into the aperture (∼12 nm) of dendritic mesoporous silica (DMSN) for near-infrared-II-enhanced tumor therapy. Upon irradiation, the hyperthermia generated by CoFe₂O₄ nanozymes unlocks the "gate" of phase-change material (PCM) for releasing GOD, which reshapes the specific tumor microenvironment (TME) through the glucose metabolism pathway. The resulting strengthened acid condition and a considerable amount of H₂O₂ efficiently initiate the cascade catalysis reactions. Moreover, highly toxic hydroxyl radicals are generated with a Co/Fe dual-cycle system of ultrasmall CoFe₂O₄ nanozymes. The in situ glutathione consumption and hypoxia relief further amplify oxidative stress. In addition, chemotherapeutic effects due to the cytotoxicity of cobalt ions enhance the therapeutic performance. Collectively, this study provides a proof of concept for TME-reshaped natural and artificial nanozyme cascade catalysis for combined reactive oxygen species-based therapy and chemotherapy.

TME-triggered MnSiO3@Met@GOx nanosystem for ATP dual-inhibited starvation/chemodynamic synergistic therapy

Adenosine triphosphate (ATP) is an essential substance for maintaining tumor cell survival and proliferation. Inhibiting the ATP-producing pathways has emerged as a promising cancer treatment strategy. However, the antitumor efficiency of ATP inhibitors is compromised by the inter-compensation of multiple ATP-producing pathways in tumor cells and biological barriers in the complex tumor microenvironment (TME). Herein, we developed metformin (Met) and glucose oxidase (GOx) co-loaded manganese silicon nanoplatform MnSiO3@Met@GOx (MMG) for TME-responsive ATP dual inhibited starvation/chemodynamic synergistic therapy. Under the mildly acidic conditions in TME, MMG was decomposed, releasing Met and GOx for effective ATP suppression by inhibiting oxidative phosphorylation (OXPHOS) and aerobic glycolysis pathways, respectively. Meanwhile, GOx-catalyzed glucose oxidation increased tumor acidity and hydrogen peroxide (H2O2) concentration in tumors, which not only accelerated MMG decomposition and drug release but also promoted manganese ions-mediated Fenton-like reaction. In vitro and in vivo experiments further demonstrated the effectiveness and biosafety of MMG-based synergistic therapy. This study provides a novel strategy for tumor treatment based on tumor metabolism regulation.

Glucose Metabolism Intervention-Facilitated Nanomedicine Therapy

Ordinarily, cancer cells possess features of abnormally increased nutrient intake and metabolic pathways. The disorder of glucose metabolism is the most important among them. Therefore, starvation therapy targeting glucose metabolism specifically, which results in metabolic disorders, restricted synthesis, and inhibition of tumor growth, has been developed for cancer therapy. However, issues such as inadequate targeting effectiveness and drug tolerance impede their clinical transformation. In recent years, nanomaterial-assisted starvation treatment has made significant progress in addressing these challenges, whether as a monotherapy or in combination with other medications. Herein, representative researches on the construction of nanosystems conducting starvation therapy are introduced. Elaborate designs and interactions between different treatment mechanisms are meticulously mentioned. Not only are traditional treatments based on glucose oxidase involved, but also newly sprung small molecule agents targeting glucose metabolism. The obstacles and potential for advancing these anticancer therapies were also highlighted in this review.

Mn2+ /Fe3+ /Co2+ and Tetrasulfide Bond Co-Incorporated Dendritic Mesoporous Organosilica as Multifunctional Nanocarriers: One-Step Synthesis and Applications for Cancer Therapy

Enriching the application of multifunctional dendritic mesoporous organosilica (DMOS) is still challenging in anti-cancer research. Herein, manganese ions, iron ions, or cobalt ions and tetrasulfide bonds are co-incorporated into the framework of DMOS to yield multifunctional nanoparticles denoted as Mn-DMOS, Fe-DMOS, or Co-DMOS by directly doping metal ions during the synthetic process. Due to co-incorporation of metal ions and tetrasulfide bonds, these designed nanocarriers have more functions rather than only for cargo delivery. As proof of concept, the nanocomposite is established based on Mn-DMOS as an efficient nanocarrier for indocyanine green (ICG) delivery and modification with polyethylene glycol. In the tumor microenvironment, the generated hydrogen sulfide (H₂ S) arising from the reaction between tetrasulfide bond and over-expressed glutathione (GSH) causes mitochondrial injury to reduce cellular respiration. The released Mn²⁺ from the rapidly decomposed nanocomposite catalyzes the endogenous hydrogen peroxide to produce oxygen (O₂ ). The photothermal effect from the released ICG initiated by the near-infrared light induces cancer cells apoptosis and simultaneously enhances the content of blood O₂ at tumor sites. Therefore, due to the GSH depletion and trimodal O₂ compensation, the photodynamic therapy efficiency of ICG has significantly improved. In brief, these designed nanocarriers will play advanced roles in cancer therapy.

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

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

A tumor microenvironment-responsive Co/ZIF-8/ICG/Pt nanoplatform for chemodynamic and enhanced photodynamic antitumor therapy

Hypoxia and the overexpression of hydrogen peroxide (H2O2) in the tumor microenvironment (TME) are conducive to cancer cell proliferation, which greatly hinders cancer treatment. Here, we design a novel TME-responsive therapeutic nanoplatform Co/ZIF-8/ICG/Pt (CZIP) to achieve chemodynamic therapy (CDT) and enhanced photodynamic therapy (PDT). In this nanoplatform, under near-infrared light (NIR) irradiation, the photosensitizer indocyanine green (ICG) can generate singlet oxygen (1O2) for cancer cell apoptosis. Meanwhile, overexpressed H2O2 in the TME could be catalyzed to generate O2 by the loaded Pt to relieve tumor hypoxia and promote the PDT-induced 1O2 production. In addition, the doped Co2+ could react with H2O2 to produce hydroxyl radicals (˙OH) for CDT. The multifunctional nanoplatform CZIP showed high biosafety and a good antitumor effect, which would provide a new route for cancer therapy.

One-Step Integration of Tumor Microenvironment-Responsive Calcium and Copper Peroxides Nanocomposite for Enhanced Chemodynamic/Ion-Interference Therapy

Recently, various metal peroxide nanomaterials have drawn increasing attention as an efficient hydrogen peroxide (H₂O₂) self-supplying agent for enhanced tumor therapy. However, a single kind of metal peroxide is insufficient to achieve more effective antitumor performance. Here, a hyaluronic acid modified calcium and copper peroxides nanocomposite has been synthesized by a simple one-step strategy. After effective accumulation at the tumor site due to the enhanced permeability and retention (EPR) effect and specific recognition of hyaluronate acid with CD44 protein on the surface of tumor cells, plenty of Ca²⁺, Cu²⁺, and H₂O₂ can be simultaneously released in acid and hyaluronidase overexpressed tumor microenvironment (TME), generating abundant hydroxyl radical through enhanced Fenton-type reaction between Cu²⁺ and self-supplying H₂O₂ with the assistance of glutathione depletion. Overloaded Ca²⁺ can lead to mitochondria injury and thus enhance the oxidative stress in tumor cells. Moreover, an unbalanced calcium transport channel caused by oxidative stress can further promote tumor calcification and necrosis, which is generally defined as ion-interference therapy. As a result, the synergistic effect of Fenton-like reaction by Cu²⁺ and mitochondria dysfunction by Ca²⁺ in ROS generation is performed. Therefore, a TME-responsive calcium and copper peroxides nanocomposite based on one-step integration has been successfully established and exhibits a more satisfactory antitumor efficiency than any single kind of metal peroxide.

Constructing virus-like SiOx/CeO2/VOx nanozymes for 1064 nm light-triggered mild-temperature photothermal therapy and nanozyme catalytic therapy

The construction of nanoplatforms with combined photothermal properties and cascading enzymatic activities has become an active area of anticancer research. However, the overheating of photothermal therapy (PTT) and the specific properties of tumor microenvironment (TME) greatly impaired the therapeutic efficiency. Herein, we rationally fabricated a virus-like SiO_x/CeO₂/VO_x (SCV) nanoplatform for 1064 nm near-infrared (NIR) triggered mild-temperature PTT and nanozyme catalytic therapy. Firstly, the virus-like shape of SiO_x/CeO₂/VO_x made it favorable for cell adhesion and improved its phagocytosis in cells, and the SCV generated an effective PTT effect upon 1064 nm laser irradiation. Particularly, the produced VO²⁺ in TME could be used as a heat shock protein inhibitor to inhibit the expression of heat shock protein 60 (HSP60) to enhance the PTT efficiency. Moreover, the SCV nanozyme exhibited obvious peroxidase-mimic (POD) catalytic activity, which could generate highly toxic free radical ions (˙OH) under acidic conditions. The mild-temperature heat and ˙OH produced by enzymatic catalysis effectively blocked the tumor growth, as verified firmly by in vitro and in vivo tests. Our designed virus-like SCV nanozyme with POD mimic enzyme activity and a mild photothermal effect may provide a new way of thinking about the combination therapy model.

Manganese silicate nanospheres-incorporated hydrogels：starvation therapy and tissue regeneration

To prevent postoperative skin tumor recurrence and repair skin wound, a glucose oxidase (GOx)-loaded manganese silicate hollow nanospheres (MS HNSs)-incorporated alginate hydrogel (G/MS-SA) was constructed for starvation-photothermal therapy and skin tissue regeneration. The MS HNSs showed a photothermal conversion efficiency of 38.5%, and endowed composite hydrogels with satisfactory photothermal effect. Taking advantage of the catalytic activity of Mn ions, the composite hydrogels could decompose hydrogen peroxide (H2O2) into oxygen (O2), which can alleviate the problem of tumor hypoxia microenvironment and endow GOx with an ability to consume glucose in the presence of O2 for tumor starvation. Meanwhile, hyperthermia triggered by near infrared (NIR) irradiation could not only accelerate the reaction rate of H2O2 decomposition by MS HNSs and glucose consumption by GOx, but also ablate tumor cells. The anti-tumor results showed that synergistic effect of starvation-photothermal therapy led to the highest death rate of tumor cells among all groups, and its anti-tumor effect was obviously improved as compared with that of single photothermal treatment or starvation treatment. Interestingly, the introduction of MS HNSs into hydrogels could distinctly promote the epithelialization of the wound beds by releasing Mn ions as compared with the hydrogels without MS HNSs. It is expected that such a multifunctional platform with starvation-photothermal therapy will be promising for treating tumor-caused skin defects in combination of its regeneration bioactivity in the future.

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.

A Tumor-Microenvironment-Responsive Nanocomposite for Hydrogen Sulfide Gas and Trimodal-Enhanced Enzyme Dynamic Therapy

Recently, enzyme dynamic therapy (EDT) has drawn much attention as a new type of dynamic therapy. However, the selection of suitable nanocarriers to deliver chloroperoxidase (CPO) and enhancement of the level of hydrogen peroxide (H2 O2 ) in the tumor microenvironment (TME) are critical factors for improving the efficiency of EDT. In this study, a rapidly decomposing nanocomposite is designed using tetra-sulfide-bond-incorporating dendritic mesoporous organosilica (DMOS) as a nanocarrier, followed by loading CPO and sodium-hyaluronate-modified calcium peroxide nanoparticles (CaO2 -HA NPs). The nanocomposite can effectively generate singlet oxygen (1 O2 ) for tumor therapy without any exogenous stimulus via trimodal-enhanced EDT, including DMOS-induced depletion of glutathione (GSH), H2 O2 compensation from CaO2 -HA NPs in mildly acidic TME, and oxidative stress caused by overloading of Ca2+ . As tetra-sulfide bonds are sensitive to GSH, DMOS can generate hydrogen sulfide (H2 S) gas as a new kind of H2 S gas nanoreactor. Additionally, the overloading of Ca2+ can cause tumor calcification to accelerate in vivo tumor necrosis and promote computed tomography imaging efficacy. Therefore, a novel H2 S gas, EDT, and Ca2+ -interference combined therapy strategy is developed.

Overcoming chemotherapy resistance using pH-sensitive hollow MnO2 nanoshells that target the hypoxic tumor microenvironment of metastasized oral squamous cell carcinoma

BACKGROUND

Smart nanoscale drug delivery systems that target acidic tumor microenvironments (TME) could offer controlled release of drugs and modulate the hypoxic TME to enhance cancer therapy. The majority of previously reported MnO₂ nanostructures are nanoparticles, nanosheets, or nanocomposites incorporated with other types of nanoparticles, which may not offer the most effective method for drug loading or for the controlled release of therapeutic payloads. Previous studies have designed MnO₂ nanoshells that achieve tumor-specific and enhanced combination therapy for localized advanced cancer. However, the therapeutic effect of MnO₂ nanoshells on metastatic cancer is still uncertain.

RESULT

Here, intelligent "theranostic" platforms were synthesized based on hollow mesoporous MnO₂ (H-MnO₂) nanoshells that were loaded with chemotherapy agents docetaxel and cisplatin (TP) to form H-MnO₂-PEG/TP nanoshells, which were designed to alleviate tumor hypoxia, attenuate angiogenesis, trigger the dissolution of Mn²⁺, and synergize the efficacy of first-class anticancer chemotherapy. The obtained H-MnO₂-PEG/TP nanoshells decomposed in the acidic TME, releasing the loaded drugs (TP) and simultaneously attenuated tumor hypoxia and hypoxia-inducible factor-1α (HIF-1α) expression by inducing endogenous tumor hydrogen peroxide (H₂O₂) decomposition. In vitro experiments showed that compared with the control group, the proliferation, colony formation and migration ability of CAL27 and SCC7 cells were significantly reduced in H-MnO₂-PEG/TP group, while cell apoptosis was enhanced, and the expression of hypoxia-inducible factor-1α(HIF-1α) was down-regulated. In vivo experiments showed that tumor to normal organ uptake ratio (T/N ratio) of mice in H-MnO₂-PEG/TP group was significantly higher than that in TP group alone (without the nanoparticle), and tumor growth was partially delayed. In the H-MnO₂-PEG/TP treatment group, HE staining showed that most of the tumor cells were severely damaged, and TUNEL assay showed cell apoptosis was up-regulated. He staining of renal and liver sections showed no obvious fibrosis, necrosis or hypertrophy, indicating good biosafety. Fluorescence staining showed that HIF-1α expression was decreased, suggesting that the accumulation of MnO₂ in the tumor caused the decomposition of H₂O₂ into O₂ and alleviated the hypoxia of the tumor.

CONCLUSION

In conclusion, a remarkable in vivo and in vitro synergistic therapeutic effect is achieved through the combination of TP chemotherapy, which simultaneously triggered a series of antiangiogenic and oxidative antitumor reactions.

Defective transition metal hydroxide-based nanoagents with hypoxia relief for photothermal-enhanced photodynamic therapy

Recently, phototherapy has attracted much attention due to its negligible invasiveness, insignificant toxicity and excellent applicability. The construction of a newly proposed nanosystem with synergistic photothermal and photodynamic tumor-eliminating properties requires a delicate structure design. In this work, a novel therapeutic nanoplatform (denoted as BCS-Ce6) based on defective cobalt hydroxide nanosheets was developed, which realized hypoxia-relieved photothermal-enhanced photodynamic therapy against cancer. Defective cobalt hydroxide exhibited high photothermal conversion efficacy at the near-infrared region (49.49% at 808 nm) as well as enhanced catalase-like activity to produce oxygen and greatly boost the singlet oxygen generation by a photosensitizer, Ce6, realizing efficacious dual-modal phototherapy. In vivo and in vitro experiments revealed that BCS-Ce6 can almost completely extinguish implanted tumors in a mouse model and present satisfactory biocompatibility during the treatment. This work sets a new angle of preparing photothermal agents and constructing comprehensive therapeutic nanosystems with the ability to modulate the hypoxic tumor microenvironment for efficient cancer therapy.