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

Intelligent responsive nanogels: New Horizons in cancer therapy

Biologically engineered nanogels formed through sophisticated intramolecular crosslinking processes represent the forefront of next-generation drug delivery systems. These innovative systems offer many advantages, like adjustable size, satisfactory biocompatibility, and minimal toxicity. Their unique attributes facilitate deep penetration and long-term retention of drugs in tumors, effectively enhancing the anti-tumor effects. Nonetheless, the rapid disintegration of nanogels and the subsequent triggering of drug release at the tumor site pose significant challenges in achieving more effective and precise tumor treatments. Therefore, increasing research has been dedicated to exploring stimulus-responsive nanogels for enhancing tumor therapy. This review aims to encapsulate the research advancements in emerging stimulus-responsive antitumor nanogels. Firstly, a detailed exposition is provided on various endogenous stimulus-responsive nanogels, encompassing factors such as pH, hypoxia, enzymes, reactive oxygen species (ROS), and glutathione (GSH). Secondly, various nanogels triggered by exogenous stimuli such as light, ultrasound, temperature, and magnetic fields are elaborately presented. Furthermore, nanogels with multifaceted stimulus-responsive properties are also skillfully designed. Finally, the future directions, application prospects, and challenges of intelligent responsive nanogels in cancer treatment are highlighted.

Use of UMFNPs/Ce6@MBs in multimodal imaging-guided sono-photodynamic combination therapy for hepatocellular carcinoma

Early diagnosis of liver cancer and appropriate treatment options are critical for obtaining a good prognosis. However, due to technical limitations, it is difficult to make an early and accurate diagnosis of liver cancer, and the traditional imaging model is relatively simple. Therefore, we synthesized multifunctional diagnostic/therapeutic nanoparticles, UMFNPs/Ce6@MBs, loaded with ultra-small manganese ferrite nanoparticles (UMFNPs) and chlorin e6 (Ce6). This nanoplatform can take full advantage of hypoxia, acidic pH (acidosis) and increased levels of reactive oxygen species (e.g. H2O2) in the tumor microenvironment (TME). Specific imaging and drug release can also enhance tumor therapy by modulating the hypoxic state of the TME to achieve the combined effect of sonodynamic therapy and photodynamic therapy (SPDT). In addition, the prepared UMFNPs/Ce6@MBs have H2O2 and pH-sensitive biodegradability and can release UMFNPs and photosensitizer Ce6 in the TME while producing O2 and Mn2+. The obtained Mn2+ ion nanoparticles can be used for T1 magnetic resonance imaging of tumor-bearing mice, and the released Ce6 can provide fluorescence imaging function at the same time. Because UMFNPs/Ce6@MB ultrasonic microbubbles show good ultrasonic imaging results, UMFNPs/Ce6@MBs can simultaneously provide multi-modal imaging functions for magnetic resonance imaging (MRI), ultrasound and fluorescence imaging. In conclusion, UMFNPs/Ce6@MBs realize the synergistic treatment of SDT and PDT under multi-mode near-infrared fluorescence imaging and CEUS monitoring, demonstrating its great potential in tumor precision medicine.

Nanomaterial-based regulation of redox metabolism for enhancing cancer therapy

Altered redox metabolism is one of the hallmarks of tumor cells, which not only contributes to tumor proliferation, metastasis, and immune evasion, but also has great relevance to therapeutic resistance. Therefore, regulation of redox metabolism of tumor cells has been proposed as an attractive therapeutic strategy to inhibit tumor growth and reverse therapeutic resistance. In this respect, nanomedicines have exhibited significant therapeutic advantages as intensively reported in recent studies. In this review, we would like to summarize the latest advances in nanomaterial-assisted strategies for redox metabolic regulation therapy, with a focus on the regulation of redox metabolism-related metabolite levels, enzyme activity, and signaling pathways. In the end, future expectations and challenges of such emerging strategies have been discussed, hoping to enlighten and promote their further development for meeting the various demands of advanced cancer therapies. It is highly expected that these therapeutic strategies based on redox metabolism regulation will play a more important role in the field of nanomedicine.

Artificial Compartments Encapsulating Enzymatic Reactions: Towards the Construction of Artificial Organelles

Cells have used compartmentalization to implement complex biological processes involving thousands of enzyme cascade reactions. Enzymes are spatially organized into the cellular compartments to carry out specific and efficient reactions in a spatiotemporally controlled manner. These compartments are divided into membrane-bound and membraneless organelles. Mimicking such cellular compartment systems has been a challenge for years. A variety of artificial scaffolds, including liposomes, polymersomes, proteins, nucleic acids, or hybrid materials have been used to construct artificial membrane-bound or membraneless compartments. These artificial compartments may have great potential for applications in biosynthesis, drug delivery, diagnosis and therapeutics, among others. This review first summarizes the typical examples of cellular compartments. In particular, the recent studies on cellular membraneless organelles (biomolecular condensates) are reviewed. We then summarize the recent advances in the construction of artificial compartments using engineered platforms. Finally, we provide our insights into the construction of biomimetic systems and the applications of these systems. This review article provides a timely summary of the relevant perspectives for the future development of artificial compartments, the building blocks for the construction of artificial organelles or cells.

Challenges of enzyme therapy: Why two players are better than one

Enzyme-based therapy has garnered significant attention for its current applications in various diseases. Despite the notable advantages associated with the use of enzymes as therapeutic agents, that could have high selectivity, affinity, and specificity for the target, their application faces challenges linked to physico-chemical and pharmacological properties. These limitations can be addressed through the encapsulation of enzymes in nanoplatforms as a comprehensive solution to mitigate their degradation, loss of activity, off-target accumulation, and immunogenicity, thus enhancing bioavailability, therapeutic efficacy, and circulation time, thereby reducing the number of administrations, and ameliorating patient compliance. The exploration of novel nanomedicine-based enzyme therapeutics for the treatment of challenging diseases stands as a paramount goal in the contemporary scientific landscape, but even then it is often not enough. Combining an enzyme with another therapeutic (e.g., a small molecule, another enzyme or protein, a monoclonal antibody, or a nucleic acid) within a single nanocarrier provides innovative multidrug-integrated therapy and ensures that both the actives arrive at the target site and exert their therapeutic effect, leading to synergistic action and superior therapeutic efficacy. Moreover, this strategic approach could be extended to gene therapy, a field that nowadays has gained increasing attention, as enzymes acting at genomic level and nucleic acids may be combined for synergistic therapy. This multicomponent therapeutic approach opens opportunities for promising future developments. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Neurological Disease Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Dual Enzyme-Encapsulated Materials for Biological Cascade Chemistry and Synergistic Tumor Starvation

Framework and polymeric nanoreactors (NRs) have distinct advantages in improving chemical reaction efficiency in the tumor microenvironment (TME). Nanoreactor-loaded oxidoreductase enzyme is activated by tumor acidity to produce H2O2 by increasing tumor oxidative stress. High levels of H2O2 induce self-destruction of the vesicles by releasing quinone methide to deplete glutathione and suppress the antioxidant potential of cancer cells. Therefore, the synergistic effect of the enzyme-loaded nanoreactors results in efficient tumor ablation via suppressing cancer-cell metabolism. The main driving force would be to take advantage of the distinct metabolic properties of cancer cells along with the high peroxidase-like activity of metalloenzyme/metalloprotein. A cascade strategy of dual enzymes such as glucose oxidase (GOx) and nitroreductase (NTR) wherein the former acts as an O2-consuming agent such as overexpression of NTR and further amplified NTR-catalyzed release for antitumor therapy. The design of cascade bioreductive hypoxia-responsive drug delivery via GOx regulates NTR upregulation and NTR-responsive nanoparticles. Herein, we discuss tumor hypoxia, reactive oxygen species (ROS) formation, and the effectiveness of these therapies. Nanoclusters in cascaded enzymes along with chemo-radiotherapy with synergistic therapy are illustrated. Finally, we outline the role of the nanoreactor strategy of cascading enzymes along with self-synergistic tumor therapy.

Self-Monitoring Theranostic Nanomaterials: Emerging Visual Agents for Real-Time Monitoring of Tumor Treatment Processes

Self-monitoring in tumor therapy is a concept that allows for real-time monitoring of the location and state of applied nanomaterials. This monitoring relies on dynamic signals, such as wave or magnetic signals, which vary in response to changes in the location and state of nanomaterials. Dynamic changes in nanomaterials can be monitored using dynamic signals, making it possible to determine and control the treatment process. Theranostic nanomaterials, which possess unique physical and chemical properties, have recently been explored as a viable option for self-monitoring. With the help of self-monitoring, theranostic nanomaterials can guide themselves to achieve region-selective treatment with higher controllability and safety. In this review, self-monitoring theranostic nanomaterials will be introduced in three parts according to their roles during therapy: tumor accumulation, tumor therapy, and metabolism. The limitations and future challenges of current self-monitoring theranostic nanomaterials will also be discussed.

Tumor Microenvironment-Triggered Self-Adaptive Polymeric Photosensitizers for Enhanced Photodynamic Therapy

Photodynamic therapy (PDT) employs photosensitizers to convert nearby oxygen into toxic singlet oxygen (1O2) upon laser light irradiation, showing great potential as a noninvasive approach for tumor ablation. However, the therapeutic efficacy of PDT is essentially impeded by π-π stacking and the aggregation of photosensitizers. Herein, we propose a tumor microenvironment-triggered self-adaptive nanoplatform to weaken the aggregation of photosensitizers by selenium-based oxidation at the tumor site. The selenide units in a selenium-based porphyrin-containing amphiphilic copolymer (PSe) could be oxidized into hydrophilic selenoxide units, leading to the nanoplatform self-expansion and stretching of the distance between intramolecular porphyrin units. This process could provide a better switch to greatly reduce the aggregation of photosensitive porphyrin units, generating more 1O2 upon laser irradiation. As verified in a series of in vitro and in vivo studies, PSe could be efficiently self-adapted at tumor sites, thus significantly enhancing the PDT therapeutic effect against solid tumors and minimizing side effects.

Targeted cancer treatment using folate-conjugated sponge-like ZIF-8 nanoparticles: a review

ZIF-8 (zeolitic imidazolate framework-8) is a potential drug delivery system because of its unique properties, which include a large surface area, a large pore capacity, a large loading capacity, and outstanding stability under physiological conditions. ZIF-8 nanoparticles may be readily functionalized with targeting ligands for the identification and absorption of particular cancer cells, enhancing the efficacy of chemotherapeutic medicines and reducing adverse effects. ZIF-8 is also pH-responsive, allowing medication release in the acidic milieu of cancer cells. Because of its tunable structure, it can be easily functionalized to design cancer-specific targeted medicines. The delivery of ZIF-8 to cancer cells can be facilitated by folic acid-conjugation. Hence, it can bind to overexpressed folate receptors on the surface of cancer cells, which holds the promise of reducing unwanted deliveries. As a result of its importance in cancer treatment, the folate-conjugated ZIF-8 was the major focus of this review.

Recent Progress on Tumor Microenvironment-Activated NIR-II Phototheranostic Agents with Simultaneous Activation for Diagnosis and Treatment

Malignant tumors seriously threaten human life and well-being. Emerging Near-infrared II (NIR-II, 1000-1700 nm) phototheranostic nanotechnology integrates diagnostic and treatment modalities, offering merits including improved tissue penetration and enhanced spatiotemporal resolution. This remarkable progress has opened promising avenues for advancing tumor theranostic research. The tumor microenvironment (TME) differs from normal tissues, exhibiting distinct attributes such as hypoxia, acidosis, overexpressed hydrogen peroxide, excess glutathione, and other factors. Capitalizing on these attributes, researchers have developed TME-activatable NIR-II phototheranostic agents with diagnostic and therapeutic attributes concurrently. Therefore, developing TME-activatable NIR-II phototheranostic agents with diagnostic and therapeutic activation holds significant research importance. Currently, research on TME-activatable NIR-II phototheranostic agents is still in its preliminary stages. This review examines the recent advances in developing dual-functional NIR-II activatable phototheranostic agents over the past years. It systematically presents NIR-II phototheranostic agents activated by various TME factors such as acidity (pH), hydrogen peroxide (H2 O2 ), glutathione (GSH), hydrogen sulfide (H2 S), enzymes, and their hybrid. This encompasses NIR-II fluorescence and photoacoustic imaging diagnostics, along with therapeutic modalities, including photothermal, photodynamic, chemodynamic, and gas therapies triggered by these TME factors. Lastly, the difficulties and opportunities confronting NIR-II activatable phototheranostic agents in the simultaneous diagnosis and treatment field are highlighted.

Co-based Nanozymatic Profiling: Advances Spanning Chemistry, Biomedical, and Environmental Sciences

Nanozymes, next-generation enzyme-mimicking nanomaterials, have entered an era of rational design; among them, Co-based nanozymes have emerged as captivating players over times. Co-based nanozymes have been developed and have garnered significant attention over the past five years. Their extraordinary properties, including regulatable enzymatic activity, stability, and multifunctionality stemming from magnetic properties, photothermal conversion effects, cavitation effects, and relaxation efficiency, have made Co-based nanozymes a rising star. This review presents the first comprehensive profiling of the Co-based nanozymes in the chemistry, biology, and environmental sciences. The review begins by scrutinizing the various synthetic methods employed for Co-based nanozyme fabrication, such as template and sol-gel methods, highlighting their distinctive merits from a chemical standpoint. Furthermore, a detailed exploration of their wide-ranging applications in biosensing and biomedical therapeutics, as well as their contributions to environmental monitoring and remediation is provided. Notably, drawing inspiration from state-of-the-art techniques such as omics, a comprehensive analysis of Co-based nanozymes is undertaken, employing analogous statistical methodologies to provide valuable guidance. To conclude, a comprehensive outlook on the challenges and prospects for Co-based nanozymes is presented, spanning from microscopic physicochemical mechanisms to macroscopic clinical translational applications.

Glucose oxidase-instructed biomineralization of calcium-based biomaterials for biomedical applications

In recent years, glucose oxidase (GOx) has aroused great research interest in the treatment of diseases related to abnormal glucose metabolisms like cancer and diabetes. However, as a kind of endogenous oxido-reductase, GOx suffers from poor stability and system toxicity in vivo. In order to overcome this bottleneck, GOx is encapsulated in calcium-based biomaterials (CaXs) such as calcium phosphate (CaP) and calcium carbonate (CaCO3) by using it as a biotemplate to simulate the natural biomineralization process. The biomineralized GOx holds improved stability and reduced side effects, due to the excellent bioactivity, biocompatibitliy, and biodegradability of CaXs. In this review, the state-of-the-art studies on GOx-mineralized CaXs are introduced with an emphasis on their application in various biomedical fields including disease diagnosis, cancer treatment, and diabetes management. The current challenges and future perspectives of GOx-mineralized CaXs are discussed, which is expected to promote further studies on these smart GOx-mineralized CaXs biomaterials for practical applications.

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.

Strategic Design of Conquering Hypoxia in Tumor for Advanced Photodynamic Therapy

Photodynamic therapy (PDT), with its advantages of high targeting, minimally invasive, and low toxicity side effects, has been widely used in the clinical therapy of various tumors, especially superficial tumors. However, the tumor microenvironment (TME) presents hypoxia due to the low oxygen (O2 ) supply caused by abnormal vascularization in neoplastic tissues and high O2 consumption induced by the rapid proliferation of tumor cells. The efficacy of oxygen-consumping PDT can be hampered by a hypoxic TME. To address this problem, researchers have been developing advanced nanoplatforms and strategies to enhance the therapeutic effect of PDT in tumor treatment. This review summarizes recent advanced PDT therapeutic strategies to against the hypoxic TME, thus enhancing PDT efficacy, including increasing O2 content in TME through delivering O2 to the tumors and in situ generations of O2 ; decreasing the O2 consumption during PDT by design of type I photosensitizers. Moreover, recent synergistically combined therapy of PDT and other therapeutic methods such as chemotherapy, photothermal therapy, immunotherapy, and gas therapy is accounted for by addressing the challenging problems of mono PDT in hypoxic environments, including tumor resistance, proliferation, and metastasis. Finally, perspectives of the opportunities and challenges of PDT in future clinical research and translations are provided.

Recent Advances in Nanoplatform Construction Strategy for Alleviating Tumor Hypoxia

Hypoxia is a typical feature of most solid tumors and has important effects on tumor cells' proliferation, invasion, and metastasis. This is the key factor that leads to poor efficacy of different kinds of therapy including chemotherapy, radiotherapy, photodynamic therapy, etc. In recent years, the construction of hypoxia-relieving functional nanoplatforms through nanotechnology has become a new strategy to reverse the current situation of tumor microenvironment hypoxia and improve the effectiveness of tumor treatment. Here, the main strategies and recent progress in constructing nanoplatforms are focused on to directly carry oxygen, generate oxygen in situ, inhibit mitochondrial respiration, and enhance blood perfusion to alleviate tumor hypoxia. The advantages and disadvantages of these nanoplatforms are compared. Meanwhile, nanoplatforms based on organic and inorganic substances are also summarized and classified. Through the comprehensive overview, it is hoped that the summary of these nanoplatforms for alleviating hypoxia could provide new enlightenment and prospects for the construction of nanomaterials in this field.

Harnessing inorganic nanomaterials for chemodynamic cancer therapy

The most important aspect of chemodynamic therapy (CDT) is the harnessing of Fenton or Fenton-like chemistry for cancer therapy within the tumor microenvironment, which occurs because of the moderate acidity and overexpressed H₂O₂ in the tumor microenvironment. Hydroxyl radicals (^•OH) produced within tumor cells via Fenton and Fenton-like reactions cause cancer cell death. Reactive oxygen species-mediated CDT demonstrates a desired anticancer impact without the need for external stimulation or the development of drug resistance. Cancer therapy based on CDT is known as a viable cancer therapy modality. This review discusses the most recent CDT advancements and provides some typical instances. As a result, potential methods for further improving CDT efficiency under the guidance of Fenton chemistry are offered.

Recent advances in upconversion nanoparticle-based nanocomposites for gas therapy

Gas therapy has attracted wide attention for the treatment of various diseases. However, a controlled gas release is highly important for biomedical applications. Upconversion nanoparticles (UCNPs) can precisely convert the long wavelength of light to ultraviolet/visible (UV/Vis) light in gas therapy for the controlled gas release owing to their unique upconversion luminescence (UCL) ability. In this review, we mainly summarized the recent progress of UCNP-based nanocomposites in gas therapy. The gases NO, O2, H2, H2S, SO2, and CO play an essential role in the physiological and pathological processes. The UCNP-based gas therapy holds great promise in cancer therapy, bacterial therapy, anti-inflammation, neuromodulation, and so on. Furthermore, the limitations and prospects of UCNP-based nanocomposites for gas therapy are also discussed.

Eco-Friendly Synthesis of MnO2 Nanorods Using Gmelina arborea Fruit Extract and Its Anticancer Potency Against MCF-7 Breast Cancer Cell Line

Introduction

Cancer disease is known due to its unregulated proliferation of cells that have evolved from the body’s regular cells. The disease develops as a result of epigenetic and genetic modifications, tumor suppressor gene inactivation, and oncogene activation. The present work describes an environmentally benign approach for the synthesis of manganese oxide nanoparticles (MnO₂ NPs) using Gmelina arborea fruit extract (GAE) in an aqueous medium.

Methods

The study evaluated the formation of MnO₂ NPs and their anticancer efficacy against MCF-7 breast cancer cell line.

Results

The formation of MnO₂ NPs was confirmed through powder X-ray diffractometer (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HR-TEM). The crystalline nature of as-prepared MnO₂ NPs was evident from XRD pattern. The morphology of the material was studied using SEM analysis, which suggested a rod-like nature with an average diameter of 50 nm. Further, the TEM and HR-TEM images confirmed the rod shape of the as-prepared MnO2 NPs with an interplanar distance of 0.271 nm. In addition, the concentric rings from selected area electron diffraction (SAED) analysis show the crystalline nature of the as-prepared material, which further supports the obtained XRD pattern. The anticancer efficacy of MnO₂ NPs was evaluated against MCF-7 breast cancer cell line, which showed up to 96% inhibition of the cells at 400 µg/mL concentration.

Conclusion

Bio-conjugation of MnO₂ NPs can provide enough scope for the therapeutic use of Gmelina arborea, assuming appropriate mechanistic evaluations are conducted.

Multifunctional phototheranostic nanoplatform based on polydopamine-manganese dioxide-IR780 iodide for effective magnetic resonance imaging-guided synergistic photodynamic/photothermal therapy

Multifunctional phototheranostics combining diagnostic and therapeutic modalities may provide a revolutionary opportunity for cancer treatment. As a promising tumor phototheranostic molecule, IR780 iodide (IR780) shows excellent photodynamic and photothermal performance under near-infrared laser irradiation; however, its hydrophobicity and instability limit its further use in organisms. This work demonstrates the design and development of a multifunctional nanoplatform (PMIDA, referring to polydopamine (PDA)-manganese dioxide (MnO₂)-IR780) for imaging-guided phototherapy. The good biocompatibility of PDA greatly improves the water solubility and photostability of IR780, and its excellent photothermal properties make PMIDA a dual photothermal therapy (PTT). MnO₂-induced generation of oxygen in the tumor microenvironment improves the hypoxia effect and photodynamic therapy (PDT) of IR780. Moreover, Mn²⁺ serves as a decent T₁-weighted magnetic resonance imaging (MRI) probe to guide treatment. Notably, in relevant cellular assays, PMIDA shows high photodynamic and photothermal effects contributing to the final therapeutic effect. The MRI-guided PDT/PTT synergistic therapy effect in vivo is demonstrated by precise tumor diagnosis and complete tumor elimination outcomes. Based on these experiments, PMIDA nanoparticles display promising effects in facilitating intravenous injection of IR780 and achieving magnetic resonance imaging (MRI)-guided phototheranostic efficacy for tumor treatment.

An Ultra-Stable, Oxygen-Supply Nanoprobe Emitting in Near-Infrared-II Window to Guide and Enhance Radiotherapy by Promoting Anti-Tumor Immunity

Currently, radiotherapy (RT) is the main method for cancer treatment. However, the hypoxic environment of solid tumors is likely to cause resistance or failure of RT. Moreover, high-dose radiation may cause side effects to surrounding normal tissues. In this study, a new type of nanozyme is developed by doping Mn (II) ions into Ag₂ Se quantum dots (QDs) emitting in the second near-infrared window (NIR-II, 1000-1700 nm). Through the catalysis of Mn (II) ions, the nanozymes can trigger the rapid decomposition of H₂ O₂ and produce O₂ . Conjugated with tumor-targeting arginine-glycine-aspartate (RGD) tripeptides and polyethylene glycol (PEG) molecules, the nanozymes are then constructed into in vivo nanoprobes for NIR-II imaging-guided RT of tumors. Owing to the radiosensitive activity of the element Ag, the nanoprobes can promote radiation energy deposition. The specific tumor-targeting and NIR-II emitting abilities of the nanoprobes facilitate the precise tumor localization, which enables precise RT with low side effects. Moreover, their ultra-stability in the living body ensures that the nanoprobes continuously produce oxygen and relieve the hypoxia of tumors to enhance RT efficacy. Guided by real-time and high-clarity imaging, the nanoprobe-mediated RT promotes anti-tumor immunity, which significantly inhibits the growth of tumors or even cures them completely.

Multifunctional MnO2 nanoparticles for tumor microenvironment modulation and cancer therapy

Tumor microenvironment (TME) is generally featured by low pH values, high glutathione (GSH) concentrations, overproduced hydrogen peroxide (H₂ O₂ ), and severe hypoxia. These characteristics could provide an interior environment for origination and residence of tumor cells and would lead to tumor progression, metastasis, and drug resistance. Therefore, the development of TME-responsive smart nanosystems has shown significant potential to enhance the efficacy of current cancer treatments. Manganese dioxide (MnO₂ )-based nanosystems have attracted growing attentions for applications in cancer treatment as an excellent TME-responsive theranostic platform, due to their tunable structures/morphologies, pH responsive degradation, and excellent catalytic activities. In this review, we mainly summarize the strategies of MnO₂ and its nanocomposites to modulate TME, such as tumor hypoxia relief, excessive GSH depletion, glucose consumption, and tumor immunosuppressive microenvironment moderation. Such MnO₂ -based TME modulation would be beneficial for a wide range of cancer therapies including photodynamic therapy, radiotherapy, sonodynamic therapy, chemodynamic therapy, starvation therapy, and immunotherapy. Next, some representative designs of MnO₂ -based nanoplatforms in other tumor therapies are highlighted. Moreover, we will discuss the challenges and future perspectives of these MnO₂ -based nanosystems for enhanced tumor treatment. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.