Manganese-Based Nanoplatform As Metal Ion-Enhanced ROS Generator for Combined Chemodynamic/Photodynamic Therapy

A Light-Triggered J-Aggregation-Regulated Therapy Conversion: from Photodynamic/Photothermal Therapy to Long-Lasting Chemodynamic Therapy for Effective Tumor Ablation

Reactive oxygen species (ROS) have become an effective tool for tumor treatment. The combination of photodynamic therapy (PDT) and chemodynamic therapy (CDT) takes advantage of various ROS and enhances therapeutic effects. However, the activation of CDT usually occurs before PDT, which hinders the sustained maintenance of hydroxyl radicals (⋅OH) and reduces the treatment efficiency. Herein, we present a light-triggered nano-system based on molecular aggregation regulation for converting cancer therapy from PDT/photothermal therapy (PTT) to a long-lasting CDT. The ordered J-aggregation enhances the photodynamic properties of the cyanine moiety while simultaneously suppressing the chemodynamic capabilities of the copper-porphyrin moiety. Upon light irradiation, Cu-PCy JNPs demonstrate strong photodynamic and photothermal effects. Meanwhile, light triggers a rapid degradation of the cyanine backbone, leading to the destruction of the J-aggregation. As a result, a long-lasting CDT is sequentially activated, and the sustained generation of ⋅OH is observed for up to 48 hours, causing potent cellular oxidative stress and apoptosis. Due to their excellent tumor accumulation, Cu-PCy JNPs exhibit effective in vivo tumor ablation through the converting therapy. This work provides a new approach for effectively prolonging the chemodynamic activity in ROS-based cancer therapy.

Mechanism of metal ion-induced cell death in gastrointestinal cancer

Gastrointestinal (GI) cancer is one of the most severe types of cancer, with a significant impact on human health worldwide. Due to the urgent demand for more effective therapeutic strategies against GI cancers, novel research on metal ions for treating GI cancers has attracted increasing attention. Currently, with accumulating research on the relationship between metal ions and cancer therapy, several metal ions have been discovered to induce cell death. In particular, the three novel modes of cell death, including ferroptosis, cuproptosis, and calcicoptosis, have become focal points of research in the field of cancer. Meanwhile, other metal ions have also been found to trigger cell death through various mechanisms. Accordingly, this review focuses on the mechanisms of metal ion-induced cell death in GI cancers, hoping to provide theoretical support for further GI cancer therapies.

Covalent organic frameworks-derived carbon nanospheres based nanoplatform for tumor specific synergistic therapy via oxidative stress amplification and calcium overload

Combinational therapy in cancer treatment that integrates the merits of different therapies is an effective approach to improve therapeutic outcomes. Herein, a simple nanoplatform (N-CNS-CaO2-HA/Ce6 NCs) that synergized chemodynamic therapy (CDT), photodynamic therapy (PDT), photothermal therapy (PTT), and Ca2+ interference therapy (CIT) has been developed to combat hypoxic tumors. With high photothermal effect, excellent peroxidase-like activity, and inherent mesoporous structure, N-doped carbon nanospheres (N-CNSs) were prepared via in situ pyrolysis of an established nanoscale covalent organic frameworks (COFs) precursor. These N-CNSs acted as PTT/CDT agents and carriers for the photosensitizer chlorin e6 (Ce6), thereby yielding a minimally invasive PDT/PTT/CDT synergistic therapy. Hyaluronic acid (HA)-modified CaO2 nanoparticles (CaO2-HA NPs) coated on the surface of the nanoplatform endowed the nanoplatform with O2/H2O2 self-supply capability to respond to and modulate the tumor microenvironment (TME), which greatly facilitated the tumor-specific performance of CDT and PDT. Moreover, the reactive oxygen species (ROS) produced during PDT and CDT enhanced the Ca2+ overloading due to CaO2 decomposition, amplifying the intracellular oxidative stress and leading to mitochondrial dysfunction. Notably, the HA molecules not only increased the cancer-targeting efficiency but also prevented CaO2 degradation during blood circulation, providing double insurance of tumor-selective CIT. Such a nanotherapeutic system possessed boosted antitumor efficacy with minimized systemic toxicity and showed great potential for treating hypoxic tumors.

Manganese drives ferroptosis of cancer cells via YAP/TAZ phase separation activated ACSL4 in OSCC

OBJECTIVE

Ferroptosis has been defined as a novel form of regulated cell death characterized by iron-dependent lipid peroxidation. Manganese has been used to induce ferroptosis in cancer cells recently. This study aims to investigate whether manganese can induce ferroptosis in oral squamous cell carcinoma (OSCC) and the underlying biological mechanisms.

MATERIALS AND METHODS

Cancer cells with or without manganese treatment were analyzed by RNA-sequencing to identify ferroptosis-related genes. Next, the activation of YAP/TAZ/ACSL4-ferroptosis signaling pathway was detected. Bioinformatic analysis and immunofluorescence assay were used to explore the phase separation of YAP/TAZ. Finally, specimens of OSCC patients were applied to analyze the clinical significance of YAP/TAZ/ACSL4.

RESULTS

RNA-sequencing analysis showed the ferroptosis-related genes and YAP/TAZ were upregulated after manganese treatment. The results of immunofluorescence, ELISA, western blotting, etc. further confirmed that manganese-induced ferroptosis depends on YAP/TAZ/ACSL4 signaling pathway. Moreover, the activation of ACSL4 was achieved by YAP/TAZ phase separation. The survival analysis in OSCC specimen suggested that the higher level of YAP/TAZ-ACSL4 axis expression indicates longer survival.

CONCLUSIONS

Manganese induces YAP/TAZ phase separation and subsequent ACSL4 activation via YAP/TAZ nuclear translocation, which facilitates ferroptosis of OSCC. Then YAP/TAZ-ACSL4 axis can be used as a potential prognostic predictor of OSCC patients.

Mn2+/CpG Oligodeoxynucleotides Codecorated Black Phosphorus Nanosheet Platform for Enhanced Antitumor Potency in Multimodal Therapy

Manganese ions (Mn2+)-coordinated nanoparticles have emerged as a promising class of antitumor nanotherapeutics, capable of simultaneously disrupting the immunosuppressive tumor microenvironment (TME) and triggering the stimulator of interferon genes (STING) pathway-dependent antitumor immunity. However, the activation of STING signaling by Mn2+-based monotherapies is suboptimal for comprehensive stimulation of antigen presenting cells and reversal of immunosuppression in the TME. Here, we report the design of a Mn2+/CpG oligodeoxynucleotides (ODNs) codecorated black phosphorus nanosheet (BPNS@Mn2+/CpG) platform based on the Mn2+ modification of BPNS and subsequent adsorption of synthetic CpG ODNs. The coordination of Mn2+ significantly improved the stability of BPNS and the adsorption of CpG ODNs. The acidic TME and endosomal compartments can disrupt the Mn2+ coordination, triggering pH-responsive release of CpG ODNs and Mn2+ to effectively activate the Toll-like receptor 9 and STING pathways. As a result, M2-type macrophages and immature dendritic cells were strongly stimulated in the TME, thereby increasing T lymphocyte infiltration and reversing the immunosuppression within the TME. Phototherapy and chemodynamic therapy, utilizing the BPNS@Mn2+/CpG platform, have demonstrated efficacy in inducing immunogenic cell death upon 808 nm laser irradiation. Importantly, the treatment of BPNS@Mn2+/CpG with laser irradiation exhibited significant therapeutic efficacy against the irradiated primary tumor and effectively suppressed the growth of nonirradiated distant tumor. Moreover, it induced a robust immune memory, providing long-lasting protection against tumor recurrence. This study demonstrated the enhanced antitumor potency of BPNS@Mn2+/CpG in multimodal therapy, and its proof-of-concept application as a metal ion-modified BPNS material for effective DNA/drug delivery and immunotherapy.

A pH-Sensitive Nanoparticle as Reactive Oxygen Species Amplifier to Regulate Tumor Microenvironment and Potentiate Tumor Radiotherapy

Background

Radiotherapy is a widely used clinical tool for tumor treatment but can cause systemic toxicity if excessive radiation is administered. Although numerous nanoparticles have been developed as radiosensitizers to reduce the required dose of X-ray irradiation, they often have limitations, such as passive reliance on radiation-induced apoptosis in tumors, and little consider the unique tumor microenvironment that contributes radiotherapy resistance.

Methods

In this study, we developed and characterized a novel self-assembled nanoparticle containing dysprosium ion and manganese ion (Dy/Mn-P). We systematically investigated the potential of Dy/Mn-P nanoparticles (NPs) as a reactive oxygen species (ROS) amplifier and radiosensitizer to enhance radiation therapy and modulate the tumor microenvironment at the cellular level. Additionally, we evaluated the effect of Dy/Mn-P on the stimulator of interferon genes (STING), an innate immune signaling pathway.

Results

Physicochemical analysis demonstrated the prepared Dy/Mn-P NPs exhibited excellent dispersibility and stability, and degraded rapidly at lower pH values. Furthermore, Dy/Mn-P was internalized by cells and exhibited selective toxicity towards tumor cells compared to normal cells. Our findings also revealed that Dy/Mn-P NPs improved the tumor microenvironment and significantly increased ROS generation under ionizing radiation, resulting in a ~70% increase in ROS levels compared to radiation therapy alone. This enhanced ROS generation inhibited ~92% of cell clone formation and greatly contributed to cytoplasmic DNA exposure. Subsequently, the activation of the STING pathway was observed, leading to the secretion of pro-inflammatory immune factors and maturation of dendritic cells (DCs).

Conclusion

Our study demonstrates that Dy/Mn-P NPs can potentiate tumor radiotherapy by improving the tumor microenvironment and increasing endogenous ROS levels within the tumor. Furthermore, Dy/Mn-P can amplify the activation of the STING pathway during radiotherapy, thereby triggering an anti-tumor immune response. This novel approach has the potential to expand the application of radiotherapy in tumor treatment.

Manganese Amplifies Photoinduced ROS in Toluidine Blue Carbon Dots to Boost MRI Guided Chemo/Photodynamic Therapy

The contrast agents and tumor treatments currently used in clinical practice are far from satisfactory, due to the specificity of the tumor microenvironment (TME). Identification of diagnostic and therapeutic reagents with strong contrast and therapeutic effect remains a great challenge. Herein, a novel carbon dot nanozyme (Mn-CD) is synthesized for the first time using toluidine blue (TB) and manganese as raw materials. As expected, the enhanced magnetic resonance (MR) imaging capability of Mn-CDs is realized in response to the TME (acidity and glutathione), and r1 and r2 relaxation rates are enhanced by 224% and 249%, respectively. In addition, the photostability of Mn-CDs is also improved, and show an efficient singlet oxygen (1 O2 ) yield of 1.68. Moreover, Mn-CDs can also perform high-efficiency peroxidase (POD)-like activity and catalyze hydrogen peroxide to hydroxyl radicals, which is greatly improved under the light condition. The results both in vitro and in vivo demonstrate that the Mn-CDs are able to achieve real-time MR imaging of TME responsiveness through aggregation of the enhanced permeability and retention effect at tumor sites and facilitate light-enhanced chemodynamic and photodynamic combination therapies. This work opens a new perspective in terms of the role of carbon nanomaterials in integrated diagnosis and treatment of diseases.

Embedding Atomically Dispersed Manganese/Gadolinium Dual Sites in Oxygen Vacancy-Enriched Biodegradable Bimetallic Silicate Nanoplatform for Potentiating Catalytic Therapy

Due to their atomically dispersed active centers, single-atom nanozymes (SAzymes) have unparalleled advantages in cancer catalytic therapy. Here, loaded with chlorin e6 (Ce6), a hydrothermally mass-produced bimetallic silicate-based nanoplatforms with atomically dispersed manganese/gadolinium (Mn/Gd) dual sites and oxygen vacancies (OVs) (PMnSA GMSNs-V@Ce6) is constructed for tumor glutathione (GSH)-triggered chemodynamic therapy (CDT) and O2 -alleviated photodynamic therapy. The band gaps of silica are significantly reduced from 2.78 to 1.88 eV by doping with metal ions, which enables it to be excited by a 650 nm laser to produce electron-hole pairs, thereby facilitating the generation of reactive oxygen species. The Gd sites can modulate the local electrons of the atom-catalyzed Mn sites, which contribute to the generation of superoxide and hydroxyl radicals (• OH). Tumor GSH-triggered Mn2+ release can convert endogenous H2 O2 to • OH and realize GSH-depletion-enhanced CDT. Significantly, the hydrothermally generated OVs can not only capture Mn and Gd atoms to form atomic sites but also can elongate and weaken the O-O bonds of H2 O2 , thereby improving the efficacy of Fenton reactions. The degraded Mn2+ /Gd3+ ions can be used as tumor-specific magnetic resonance imaging contrast agents. All the experimental results demonstrate the great potential of PMnSA GMSNs-V@Ce6 as cancer theranostic agent.

Tellurium-driven maple leaf-shaped manganese nanotherapeutics reshape tumor microenvironment via chemical transition in situ to achieve highly efficient radioimmunotherapy of triple negative breast cancer

The therapeutic efficacy of radioimmunotherapy against triple negative breast cancer (TNBC) is largely limited by the complicated tumor microenvironment (TME) and its immunosuppressive state. Thus developing a strategy to reshape TME is expected to achieve highly efficient radioimmunotherapy. Therefore, we designed and synthesized a tellurium (Te)-driven maple leaf manganese carbonate nanotherapeutics (MnCO₃@Te) by gas diffusion method, but also provided a chemical catalytic strategy in situ to augment ROS level and activate immune cells for improving cancer radioimmunotherapy. As expected, with the help of H₂O₂ in TEM, MnCO₃@Te heterostructure with reversible Mn³⁺/Mn²⁺ transition could catalyze the intracellular ROS overproduction to amplify radiotherapy. In addition, by virtue of the ability to scavenge H⁺ in TME by carbonate group, MnCO₃@Te directly promote the maturation of dendritic cells and macrophage M1 repolarization by stimulator of interferon genes (STING) pathway activation, resulting in remodeling immuno-microenvironment. As a result, MnCO₃@Te synergized with radiotherapy and immune checkpoint blockade therapy effectively inhibited the breast cancer growth and lung metastasis in vivo. Collectively, these findings indicate that MnCO₃@Te as an agonist, successfully overcome radioresistance and awaken immune systems, showing promising potential for solid tumor radioimmunotherapy.

The Application of Biomedicine in Chemodynamic Therapy: From Material Design to Improved Strategies

Chemodynamic therapy (CDT) has garnered significant interest as an innovative approach for cancer treatment, owing to its notable tumor specificity and selectivity, minimal systemic toxicity and side effects, and absence of the requirement for field stimulation during treatment. This treatment utilizes nanocatalytic medicines containing transitional metals to release metal ions within tumor cells, subsequently initiating Fenton and Fenton-like reactions. These reactions convert hydrogen peroxide (H2O2) into hydroxyl radical (•OH) specifically within the acidic tumor microenvironment (TME), thereby inducing apoptosis in tumor cells. However, insufficient endogenous H2O2, the overexpressed reducing substances in the TME, and the weak acidity of solid tumors limit the performance of CDT and restrict its application in vivo. Therefore, a variety of nanozymes and strategies have been designed and developed in order to potentiate CDT against tumors, including the application of various nanozymes and different strategies to remodel TME for enhanced CDT (e.g., increasing the H2O2 level in situ, depleting reductive substances, and lowering the pH value). This review presents an overview of the design and development of various nanocatalysts and the corresponding strategies employed to enhance catalytic drug targeting in recent years. Additionally, it delves into the prospects and obstacles that lie ahead for the future advancement of CDT.

Platinum Drug-Incorporating Polymeric Nanosystems for Precise Cancer Therapy

Platinum (Pt) drugs are widely used in clinic for cancer therapy, but their therapeutic outcomes are significantly compromised by severe side effects and acquired drug resistance. With the emerging immunotherapy and imaging-guided cancer therapy, precise delivery and release of Pt drugs have drawn great attention these days. The targeting delivery of Pt drugs can greatly increase the accumulation at tumor sites, which ultimately enhances antitumor efficacy. Further, with the combination of Pt drugs and other theranostic agents into one nanosystem, it not only possesses excellent synergistic efficacy but also achieves real-time monitoring. In this review, after the introduction of Pt drugs and their characteristics, the recent progress of polymeric nanosystems for efficient delivery of Pt drugs is summarized with an emphasis on multi-modal synergistic therapy and imaging-guided Pt-based cancer treatment. In the end, the conclusions and future perspectives of Pt-encapsulated nanosystems are given.

Mn-Si-based nanoparticles-enhanced inhibitory effect on tumor growth and metastasis in photo-immunotherapy

The anticancer effect of phototherapy has been limited by some factors, including the easy degradation of photo agents, the complex tumor microenvironment, and the limited immune activation capacity, which impedes its efficiency in inhibiting tumor growth and tumor metastasis. Herein, Mn-doped mesoporous silica nanoparticles were synthesized to load the photo agent of IR 780, which were further coated with Mn (IMM). Notably, the combination of IMM and an 808 nm laser irradiation simultaneously inhibited the growth of primary tumors and distant untreated tumors in a bilateral animal model, which could be attributed to the protection of IMM to IR 780, the regulation functions to the tumor microenvironment, as well as the enhanced immune activation capacity. This work highlighted an alternative strategy for enhancing the inhibitory effect on both tumor growth and tumor metastasis in the combinational anticancer therapy of phototherapy and immunotherapy (photo-immunotherapy).

Bioinorganic Modulators of Ferroptosis: A Review of Recent Findings

Ferroptosis was first reported as a separate modality of regulated cell death in 2008 and distinguished under its current name in 2012 after it was first induced with erastin. In the following decade, multiple other chemical agents were researched for their pro- or anti-ferroptotic properties. Complex organic structures with numerous aromatic moieties make up the majority of this list. This review fills a more overlooked niche by gathering, outlining and setting out conclusions regarding less prominent cases of ferroptosis induced by bioinorganic compounds and reported on within the last few years. The article contains a short summary of the application of bioinorganic chemicals based on gallium, several chalcogens, transition metals and elements known as human toxicants used for the purpose of evoking ferroptotic cell death in vitro or in vivo. These are used in the form of free ions, salts, chelates, gaseous and solid oxides or nanoparticles. Knowledge of how exactly these modulators promote or inhibit ferroptosis could be beneficial in the context of future therapies aimed against cancer or neurodegenerative diseases, respectively.

Flexible Hollow Human Serum Albumin-Catalase Nanocapsules with High Accumulation and Uptake Ability for Enhanced Photodynamic Therapy

Introduction

Photodynamic therapy (PDT) has attracted increasing attention for tumor treatment because of its minimal invasiveness and specific spatiotemporal selectivity. However, insufficient tumor accumulation and low cellular uptake of photosensitizers limit its therapeutic efficacy.

Methods

In this study, flexible hollow human serum albumin/catalase nanocapsules (HSA/CATs) were created using a core-assisted protein-coating method and combined with the photosensitizer chlorin e6 (HSA/CAT@Ce6) for PDT.

Results and Discussion

Transmission electron microscopy (TEM) images demonstrate that HSA/CAT nanocapsules are flexible, with a uniform diameter (310 nm) and a well-defined hollow structure. Thanks to their flexibility, HSA/CAT@Ce6 nanocapsules show a higher cellular uptake than rigid nanoparticles. The nanocapsules effectively generate reactive oxygen species (ROS) in 4T1 cells because of their high cellular uptake and catalytic capacity, remarkably enhancing their in vitro PDT efficacy. In addition, the in vivo tumor accumulation of HSA/CAT@Ce6 nanocapsules is significantly larger than that of rigid nanoparticles and Ce6, meaning they are highly effective in tumor cell ablation. This demonstrates that our flexible nanoplatform holds great promise for enhancing PDT of tumor.

Nanotherapeutic Intervention in Photodynamic Therapy for Cancer

The clinical need for photodynamic therapy (PDT) has been growing for several decades. Notably, PDT is often used in oncology to treat a variety of tumors since it is a low-risk therapy with excellent selectivity, does not conflict with other therapies, and may be repeated as necessary. The mechanism of action of PDT is the photoactivation of a particular photosensitizer (PS) in a tumor microenvironment in the presence of oxygen. During PDT, cancer cells produce singlet oxygen (¹O₂) and reactive oxygen species (ROS) upon activation of PSs by irradiation, which efficiently kills the tumor. However, PDT's effectiveness in curing a deep-seated malignancy is constrained by three key reasons: a tumor's inadequate PS accumulation in tumor tissues, a hypoxic core with low oxygen content in solid tumors, and limited depth of light penetration. PDTs are therefore restricted to the management of thin and superficial cancers. With the development of nanotechnology, PDT's ability to penetrate deep tumor tissues and exert desired therapeutic effects has become a reality. However, further advancement in this field of research is necessary to address the challenges with PDT and ameliorate the therapeutic outcome. This review presents an overview of PSs, the mechanism of loading of PSs, nanomedicine-based solutions for enhancing PDT, and their biological applications including chemodynamic therapy, chemo-photodynamic therapy, PDT-electroporation, photodynamic-photothermal (PDT-PTT) therapy, and PDT-immunotherapy. Furthermore, the review discusses the mechanism of ROS generation in PDT advantages and challenges of PSs in PDT.

Toxicology assessment of manganese oxide nanomaterials with enhanced electrochemical properties using human in vitro models representing different exposure routes

In the present study, a comparative human toxicity assessment between newly developed Mn₃O₄ nanoparticles with enhanced electrochemical properties (GNA35) and their precursor material (Mn₃O₄) was performed, employing different in vitro cellular models representing main exposure routes (inhalation, intestinal and dermal contact), namely the human alveolar carcinoma epithelial cell line (A549), the human colorectal adenocarcinoma cell line (HT29), and the reconstructed 3D human epidermal model EpiDerm. The obtained results showed that Mn₃O₄ and GNA35 harbour similar morphological characteristics, whereas differences were observed in relation to their surface area and electrochemical properties. In regard to their toxicological properties, both nanomaterials induced ROS in the A549 and HT29 cell lines, while cell viability reduction was only observed in the A549 cells. Concerning their skin irritation potential, the studied nanomaterials did not cause a reduction of the skin tissue viability in the test conditions nor interleukin 1 alpha (IL- 1 α) release. Therefore, they can be considered as not irritant nanomaterials according to EU and Globally Harmonized System of Classification and Labelling Chemicals. Our findings provide new insights about the potential harmful effects of Mn₃O₄ nanomaterials with different properties, demonstrating that the hazard assessment using different human in vitro models is a critical aspect to increase the knowledge on their potential impact upon different exposure routes.

A tumor pH-responsive autocatalytic nanoreactor as a H2O2 and O2 self-supplying depot for enhanced ROS-based chemo/photodynamic therapy

Combining the internal force-driven chemodynamic therapy (CDT) and the external energy-triggered photodynamic therapy (PDT) holds great promise to achieve an advanced anticancer effect based on reactive oxygen species (ROS). However, the insufficient oxy-substrates supply in tumor microenvironment, like hydrogen peroxide (H₂O₂) and oxygen (O₂), is the Achilles heel that greatly restricts the efficacy of this ROS-based treatment. Herein, the construction of a copper peroxide-based tumor pH-responsive autocatalytic nanoreactor (CESAR), via an albumin-mediated biomimetic mineralization strategy is described. The decoration of human serum albumin endows the nanoreactor good hydrophilicity and biocompatibility, which is highly desired for the metal-based materials. Upon exposure to acidic tumor microenvironment, CESAR presents a pH-triggered disintegration with Cu²⁺, H₂O₂ and O₂ generated instantly. The generated H₂O₂ complements the hyperoxide deficiency and initiates a localized Fenton-like reaction with the assistance of Cu²⁺ for highly toxic hydroxyl radicals (•OH) production for improving CDT. The evolved O₂ gas enables hypoxia relief for enhanced Ce6-mediated PDT. This H₂O₂/O₂ self-supplying strategy significantly amplifies the tumor oxidative damage and gains an optimal treatment outcome, which offers a new paradigm for optimizing the tumor therapeutic options limited by oxide or hyperoxide deficiency, not only for CDT/PDT, but also other oxy-substrates involved strategies. STATEMENT OF SIGNIFICANCE: The shortage of oxy-substrates in the tumor microenvironment remains a great challenge for ROS-based cancer therapy. Herein, we introduce human serum albumin as a scaffold to stabilize copper peroxide nanomaterials for constant production of H₂O₂ and O₂ to enhance chemodynamic/photodynamic therapy. The tumor pH-triggered H₂O₂/O₂ production and Cu²⁺ release are confirmed, assuring the strategy of a highly precise, effective way to destroy tumor without any side effects. This work lends new and exciting insights into the engineering design of autocatalytic oxy-substrates self-supply nanoreactor for overcoming the bottlenecks, like the oxy-substrates deficiency of CDT/PDT and the poor stability of metal peroxides, to achieve highly effective chemodynamic/photodynamic therapy.

Manganese induces tumor cell ferroptosis through type-I IFN dependent inhibition of mitochondrial dihydroorotate dehydrogenase

Ferroptosis is a novel form of regulated cell death characterized by the iron-dependent accumulation of lipid peroxides to lethal levels, which is morphologically, biochemically, and genetically distinct from apoptosis, necroptosis, autophagy, and pyroptosis. Manganese play an important role in innate immunity and antitumor immunity. Many manganese-based nanomaterials induce tumor cell death by catalyzing the production of reactive oxygen species (ROS) within the tumor. However, the exact underlying mechanisms remain unclear. As research on ferroptosis advances and its regulatory mechanisms in tumors continue to be refined, more evidence has suggested that triggering ferroptosis in tumor cells is an effective strategy for tumor treatment. In this study, we found that administration of MnCl₂ to tumor cells resulted in lipid peroxidation and increased the levels of mitochondrial ROS, consequently leading to ferroptosis. Dihydroorotate dehydrogenase (DHODH)-mediated ferroptosis defence is a targetable vulnerability in cancer. We show that MnCl₂ downregulated DHODH expression in tumor cells, resulting in increased mitochondrial ROS and lipid peroxidation to induce ferroptosis. In addition, MnCl₂ enhanced the phosphorylation levels of STING, TBK1, and IRF3 and upregulated the expression of type-I interferon (IFN), produced by the cGAS-STING signaling pathway. When inhibiting the cGAS-STING signaling pathway or type-I IFN, DHODH expression was restored, reversing lipid peroxidation and ROS production and rescuing MnCl₂-induced ferroptosis.. Knockout of IFNAR1 or overexpression of DHODH weakens the antitumor effect of MnCl₂. Mechanistically, these results revealed that Manganese treatment-activated cGAS-STING signaling promote mitochondrial lipid peroxidation and ROS production by releasing type-I IFNs that reduce DHODH function and thereby inducing ferroptosis in tumor cells. This may provide a new strategy to complement existing antitumor treatment regimens.

A Review on the Recent Advancements on Therapeutic Effects of Ions in the Physiological Environments

This review focuses on the therapeutic effects of ions when released in physiological environments. Recent studies have shown that metallic ions like Ag+, Sr2+, Mg2+, Mn2+, Cu2+, Ca2+, P+5, etc., have shown promising results in drug delivery systems and regenerative medicine. These metallic ions can be loaded in nanoparticles, mesoporous bioactive glass nanoparticles (MBGNs), hydroxyapatite (HA), calcium phosphates, polymeric coatings, and salt solutions. The metallic ions can exhibit different functions in the physiological environment such as antibacterial, antiviral, anticancer, bioactive, biocompatible, and angiogenic effects. Furthermore, the metals/metalloid ions can be loaded into scaffolds to improve osteoblast proliferation, differentiation, bone development, fibroblast growth, and improved wound healing efficacy. Moreover, different ions possess different therapeutic limits. Therefore, further mechanisms need to be developed for the highly controlled and sustained release of these ions. This review paper summarizes the recent progress in the use of metallic/metalloid ions in regenerative medicine and encourages further study of ions as a solution to cure diseases.

Open-Source and Reduced-Expenditure Nanosystem with ROS Self-Amplification and Glutathione Depletion for Simultaneous Augmented Chemodynamic/Photodynamic Therapy

Reactive oxygen species (ROS)-induced cell apoptosis has emerged as an efficient strategy for cancer therapy. However, tumor hypoxia and insufficient amounts of endogenous hydrogen peroxide (H₂O₂) in the tumor microenvironment are currently the main limitations of photodynamic therapy (PDT) and chemodynamic therapy (CDT). Moreover, the glutathione (GSH) scavenging effect on ROS further hinders the efficiency of ROS-mediated therapy. Here, a CaO₂-based nanosystem (named as CF@CO@HC) with ROS self-amplification and GSH-depletion abilities was developed by a bottom-up approach. This hybrid nanoparticle consisted of a photosensitizer-doped calcium peroxide (CaO₂) core (CaO₂-FM), a hybrid organosilica framework (Cu-ONS) incorporated with Fenton reagents (Cu²⁺) and tetrasulfide groups, and a local hydrophobic cage (HC) shell. The photosensitizer was fluorescein derivative 4-FM with a thermally activated delayed fluorescence (TADF) property. The HC shell was built to protect the CaO₂ and the photosensitizer from being attacked by water. Upon being internalized into cancer cells, the nanosystem was decomposed through the reduction reactions of Cu²⁺ and the tetrasulfide bond-doped silica shell by GSH, thus releasing Cu⁺ for Cu⁺-mediated CDT. Meanwhile, the exposed CaO₂-FM can react with H₂O to liberate photosensitizer 4-FM and generate H₂O₂ and O₂ to overcome barriers in CDT and PDT. Thus, our study provided an open-source and reduced-expenditure strategy via GSH depletion and ROS self-amplification behaviors for ROS generation and significantly achieved an improved synergistic PDT/CDT for cancers.

A tumour microenvironment-mediated Bi2-xMnxO3 hollow nanospheres via glutathione depletion for photothermal enhanced chemodynamic collaborative therapy

Photothermal-enhanced chemodynamic therapy (CDT) has been attracting increasing attention for effective tumour treatment. Nevertheless, even though Mn-based nanostructures are promising CDT agents, their photothermal conversion capacities are not good enough for an ideal combination therapy. In this work, a bifunctional Bi_2-xMn_xO₃ nanoplatform was developed, with tumour microenvironment (TME)-triggered photothermal therapy (PTT)-enhanced CDT, for a collaborative therapy for tumours. The doping of a small amount of Bi tuned the photothermal and CDT performance of Bi_2-xMn_xO₃, thus promoting the photothermal conversion ability as well as accelerating the ˙OH generation. The existence of reductive Mn⁴⁺ could disrupt the internal tumour redox balance by enhancing glutathione (GSH) consumption to improve the CDT effect. Meanwhile, the mild photothermal effect could accelerate the depletion of GSH and the generation of ˙OH in the tumour region after laser irradiation, thus promoting the CDT effect. This manganese-based nanoplatform provides a good strategy for tumour therapy via TME-mediated PTT-enhanced CDT.

Intracellular marriage of bicarbonate and Mn ions as "immune ion reactors" to regulate redox homeostasis and enhanced antitumor immune responses

Background

Different from Fe ions in Fenton reaction, Mn ions can function both as catalyst for chemodynamic therapy and immune adjuvant for antitumor immune responses. In Mn-mediated Fenton-like reaction, bicarbonate (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{HCO}}_{3}^{ - }$$\end{document}HCO3-), as the most important component to amplify therapeutic effects, must be present, however, intracellular \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{HCO}}_{3}^{ - }$$\end{document}HCO3- is strictly limited because of the tight control by live cells.

Results

Herein, Stimuli-responsive manganese carbonate-indocyanine green complexes (MnCO₃-ICG) were designed for intracellular marriage of bicarbonate and Mn ions as “immune ion reactors” to regulate intracellular redox homeostasis and antitumor immune responses. Under the tumor acidic environment, the biodegradable complex can release “ion reactors” of Mn²⁺ and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{HCO}}_{3}^{ - }$$\end{document}HCO3-, and ICG in the cytoplasm. The suddenly increased \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{HCO}}_{3}^{ - }$$\end{document}HCO3- in situ inside the cells regulate intracellular pH, and accelerate the generation of hydroxyl radicals for the oxidative stress damage of tumors cells because \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{HCO}}_{3}^{ - }$$\end{document}HCO3- play a critical role to catalyze Mn-mediated Fenton-like reaction. Investigations in vitro and in vivo prove that the both CDT and phototherapy combined with Mn²⁺-enhanced immunotherapy effectively suppress tumor growth and realize complete tumor elimination.

Conclusions

The combination therapy strategy with the help of novel immune adjuvants would produce an enhanced immune response, and be used for the treatment of deep tumors in situ.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01404-x.

Ion drugs for precise orthotopic tumor management by in situ the generation of toxic ion and drug pools

Background: Asymmetric intracellular and extracellular ionic gradients are critical to the survivability of mammalian cells. Given the importance of manganese (Mn²⁺), calcium (Ca²⁺), and bicarbonate (HCO₃ ^-) ions, any alteration of the ion-content balance could induce a series of cellular responses. HCO₃ ^- plays an indispensable role for Mn-mediated Fenton-like reaction, but this is difficult to achieve because bicarbonates are tightly regulated by live cells, and are limited in anticancer efficacy. Methods: A responsive and biodegradable biomineral, Mn-doped calcium carbonate integrated with dexamethasone phosphate (DEX) (Mn:CaCO₃-DEX), was reported to enable synergistic amplification of tumor oxidative stress, reduce inflammation, and induce Ca-overload cell apoptosis by elevating the intracellular and extracellular ionic gradients. Results: Under the acidic environment in tumor region, the ions (Mn²⁺, CO₃ ^2-, Ca²⁺) were released by the degradation of Mn:CaCO₃-DEX and then escalated oxidative stresses by triggering a HCO₃ ^--indispensable Mn-based Fenton-like reaction and breaking Ca²⁺ ion homeostasis to cause oxidative stress in cells and calcification. The released anti-inflammatory and antitumor drug, DEX, could alleviate the inflammatory environment. The investigations in vitro and in vivo demonstrated that the synergistic oncotherapy could effectively inhibit the growth of subcutaneous tumors and orthotopic liver tumors. Notably, normal cells showed greater tolerance of the synergistic influences. Conclusion: As an ion drug, Mn:CaCO₃-DEX is an excellent potential diagnostic agent for precise orthotopic tumor management by the generation in situ of toxic ion and drug pools in the environment of tumor region, with synergistic effects of enhanced chemodynamic therapy, calcification, and anti-inflammation effects.

Chemodynamic Therapy via Fenton and Fenton-Like Nanomaterials: Strategies and Recent Advances

Chemodynamic therapy (CDT), a novel cancer therapeutic strategy defined as the treatment using Fenton or Fenton-like reaction to produce •OH in the tumor region, was first proposed by Bu, Shi, and co-workers in 2016. Recently, with the rapid development of Fenton and Fenton-like nanomaterials, CDT has attracted tremendous attention because of its unique advantages: 1) It is tumor-selective with low side effects; 2) the CDT process does not depend on external field stimulation; 3) it can modulate the hypoxic and immunosuppressive tumor microenvironment; 4) the treatment cost of CDT is low. In addition to the Fe-involved CDT strategies, the Fenton-like reaction-mediated CDT strategies have also been proposed, which are based on many other metal elements including copper, manganese, cobalt, titanium, vanadium, palladium, silver, molybdenum, ruthenium, tungsten, cerium, and zinc. Moreover, CDT has been combined with other therapies like chemotherapy, radiotherapy, phototherapy, sonodynamic therapy, and immunotherapy for achieving enhanced anticancer effects. Besides, there have also been studies that extend the application of CDT to the antibacterial field. This review introduces the latest advancements in the nanomaterials-involved CDT from 2018 to the present and proposes the current limitations as well as future research directions in the related field.

Nanocatalyst-Mediated Chemodynamic Tumor Therapy

Traditional tumor treatments, including chemotherapy, radiotherapy, photodynamic therapy, and photothermal therapy, are developed and used to treat different types of cancer. Recently, chemodynamic therapy (CDT) has been emerged as a novel cancer therapeutic strategy. CDT utilizes Fenton or Fenton-like reaction to generate highly cytotoxic hydroxyl radicals (•OH) from endogenous hydrogen peroxide (H₂ O₂ ) to kill cancer cells, which displays promising therapeutic potentials for tumor treatment. However, the low catalytic efficiency and off-target side effects of Fenton reaction limit the biomedical application of CDT. In this regard, various strategies are implemented to potentiate CDT against tumor, including retrofitting the tumor microenvironment (e.g., increasing H₂ O₂ level, decreasing reductive substances, and reducing pH), enhancing the catalytic efficiency of nanocatalysts, and other strategies. This review aims to summarize the development of CDT and summarize these recent progresses of nanocatalyst-mediated CDT for antitumor application. The future development trend and challenges of CDT are also discussed.

Hybrid Carbon Dot Assembly as a Reactive Oxygen Species Nanogenerator for Ultrasound-Assisted Tumor Ablation

The efficacy of reactive oxygen species (ROS)-based therapy is substantially constrained by the limited ROS generation, stern activation conditions, and lack of a straightforward reaction paradigm. Carbon dots (CDs) have been highly sought after for therapeutic applications for their biocompatibility and intrinsic fluorescence imaging capabilities, making them suitable for ROS generation. Herein, we synthesized a CD-based ultrasmall hybrid nanostructure possessing active sites of Mo, Cu, and IR-780 dye. After cooperative self-assembly with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-poly(ethylene glycol), the obtained assembly (CMIR-CDa) exhibits near-infrared fluorescence imaging and photoacoustic tomography. Interestingly, CMIR-CDa can generate singlet oxygen (1O2), hydroxyl radical (·OH), and superoxide radical anion (O2 • -) upon ultrasound stimulus owing to its sonosensitizing and enzyme-mimicking properties, showing an enhanced efficacy for tumor ablation in vivo. The collective in vitro and in vivo results indicate that CMIR-CDa has a high potency as an ROS nanogenerator under US irradiation, even at a low concentration. The present study offers an approach for engineering hybrid CDs in a bioinspired way for intratumoral ROS augmentation in response to deep tissue penetrable external stimuli.

Manipulating Intratumoral Fenton Chemistry for Enhanced Chemodynamic and Chemodynamic-Synergized Multimodal Therapy

Chemodynamic therapy (CDT) uses the tumor microenvironment-assisted intratumoral Fenton reaction for generating highly toxic hydroxyl free radicals (•OH) to achieve selective tumor treatment. However, the limited intratumoral Fenton reaction efficiency restricts the therapeutic efficacy of CDT. Recent years have witnessed the impressive development of various strategies to increase the efficiency of intratumoral Fenton reaction. The introduction of these reinforcement strategies can dramatically improve the treatment efficiency of CDT and further promote the development of enhanced CDT (ECDT)-based multimodal anticancer treatments. In this review, the authors systematically introduce these reinforcement strategies, from their basic working principles, reinforcement mechanisms to their representative clinical applications. Then, ECDT-based multimodal anticancer therapy is discussed, including how to integrate these emerging Fenton reinforcement strategies for accelerating the development of multimodal anticancer therapy, as well as the synergistic mechanisms of ECDT and other treatment methods. Eventually, future direction and challenges of ECDT and ECDT-based multimodal synergistic therapies are elaborated, highlighting the key scientific problems and unsolved technical bottlenecks to facilitate clinical translation.

Nanomedicine potentiates mild photothermal therapy for tumor ablation

The booming photothermal therapy (PTT) has achieved great progress in non-invasive oncotherapy, and paves a novel way for clinical oncotherapy. Of note, mild temperature PTT (mPTT) of 42–45 °C could avoid treatment bottleneck of the traditional PTT, including nonspecific injury to normal tissues, vasculature and host antitumor immunity. However, cancer cells can resist mPTT via heat shock response and autophagy, thus leading to insufficient mPTT monotherapy to ablate tumor. To overcome the deficient antitumor efficacy caused by thermo-resistance of cancer cells and mono mPTT, synergistic therapies towards cancer cells have been conducted with mPTT. This review summarizes the recent advances in nanomedicine-potentiated mPTT for cancer treatment, including strategies for enhanced single-mode mPTT and mPTT plus synergistic therapies. Moreover, challenges and prospects for clinical translation of nanomedicine-potentiated mPTT are discussed.

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.

Tumor microenvironment: a prospective target of natural alkaloids for cancer treatment

Malignant tumor has become one of the major diseases that seriously endangers human health. Numerous studies have demonstrated that tumor microenvironment (TME) is closely associated with patient prognosis. Tumor growth and progression are strongly dependent on its surrounding tumor microenvironment, because the optimal conditions originated from stromal elements are required for cancer cell proliferation, invasion, metastasis and drug resistance. The tumor microenvironment is an environment rich in immune/inflammatory cells and accompanied by a continuous, gradient of hypoxia and pH. Overcoming immunosuppressive environment and boosting anti-tumor immunity may be the key to the prevention and treatment of cancer. Most traditional Chinese medicine have been proved to have good anti-tumor activity, and they have the advantages of better therapeutic effect and few side effects in the treatment of malignant tumors. An increasing number of studies are giving evidence that alkaloids extracted from traditional Chinese medicine possess a significant anticancer efficiency via regulating a variety of tumor-related genes, pathways and other mechanisms. This paper reviews the anti-tumor effect of alkaloids targeting tumor microenvironment, and further reveals its anti-tumor mechanism through the effects of alkaloids on different components in tumor microenvironment.

X-ray-facilitated redox cycling of nanozyme possessing peroxidase-mimicking activity for reactive oxygen species-enhanced cancer therapy

Nanomaterials with shifting or mixed redox states is one of the most common studied nanozyme with peroxidase-like activity for chemodynamic therapy (CDT), which can decompose hydrogen peroxide (H₂O₂) of tumor microenvironment into highly toxic reactive oxygen species (ROS) by a nano-catalytic way. However, most of them exhibit an insufficient catalytic efficiency due to their dependence on catalytic condition. Herein, a potential methodology is proposed to enhance their enzymatic activity by accelerating the redox cycling of these nanomaterials with shifting or mixed redox states in the presence of X-ray. In this study, the nanocomposite consisting of SnS₂ nanoplates and Fe₃O₄ quantum dots with shifting or mixed redox states (Fe²⁺/Fe³⁺) is used to explore the strategy. Under external X-ray irradiation, SnS₂ cofactor as electron donor can be triggered to transfer electrons to Fe₃O₄, which promotes the regeneration of Fe²⁺ sites on the surface of the Fe₃O₄. Consequently, the regenerated Fe²⁺ sites react with the overexpressed H₂O₂ to persistently generate ROS for enhanced tumor therapy. The designed nanocomposite displays the synergistic effects of radiotherapy and CDT. The strategy provides a new avenue for the development of artificial nanozymes with shifting or mixed redox states in precise cancer treatments based on X-ray-enhanced enzymatic efficacy.

Tumor Microenvironment-Modulated Nanozymes for NIR-II-Triggered Hyperthermia-Enhanced Photo-Nanocatalytic Therapy via Disrupting ROS Homeostasis

Purpose

Reactive oxygen species (ROS) are a group of signaling biomolecules that play important roles in the cell cycle. When intracellular ROS homeostasis is disrupted, it can induce cellular necrosis and apoptosis. It is desirable to effectively cascade-amplifying ROS generation and weaken antioxidant defense for disrupting ROS homeostasis in tumor microenvironment (TME), which has been recognized as a novel and ideal antitumor strategy. Multifunctional nanozymes are highly promising agents for ROS-mediated therapy.

Methods

This study constructed a novel theranostic nanoagent based on PEG@Cu_2-xS@Ce6 nanozymes (PCCNs) through a facile one-step hydrothermal method. We systematically investigated the photodynamic therapy (PDT)/photothermal therapy (PTT) properties, catalytic therapy (CTT) and glutathione (GSH) depletion activities of PCCNs, antitumor efficacy induced by PCCNs in vitro and in vivo.

Results

PCCNs generate singlet oxygen (¹O₂) with laser (660 nm) irradiation and use catalytic reactions to produce hydroxyl radical (•OH). Moreover, PCCNs show the high photothermal performance under NIR II 1064-nm laser irradiation, which can enhance CTT/PDT efficiencies to increase ROS generation. The properties of O₂ evolution and GSH consumption of PCCNs achieve hypoxia-relieved PDT and destroy cellular antioxidant defense system respectively. The excellent antitumor efficacy in 4T1 tumor-bearing mice of PCCNs is achieved through disrupting ROS homeostasis-involved therapy under the guidance of photothermal/photoacoustic imaging.

Conclusion

Our study provides a proof of concept of “all-in-one” nanozymes to eliminate tumors via disrupting ROS homeostasis.

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.

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.

Organic/inorganic nanohybrids rejuvenate photodynamic cancer therapy

The development of nanotechnology has changed the 100-year-old paradigm of photodynamic therapy (PDT), in which organic/inorganic hybrid nanomaterials have made great contributions. In this review, we first describe the mechanisms of PDT and discuss the limitations of conventional PDT. On this basis, we summarize recent progress in organic/inorganic nanohybrids-based photodynamic agents, highlighting how these nanohybrids can be programmed to overcome challenges in photodynamic cancer therapy.

Manganese-deposited iron oxide promotes tumor-responsive ferroptosis that synergizes the apoptosis of cisplatin

Background: Ferroptosis is a form of iron-dependent programmed cell death that differs from apoptosis with regards to both mechanism and cell morphology. Therefore, ferroptotic-based cancer therapy has shown significant potential to overcome the weaknesses of conventional therapeutics mediated by apoptosis pathways. Effective ferroptosis can be induced by the intracellular Fenton reaction that is dependent on the adequate supply of iron ions and H2O2 in cells. However, these are often insufficient due to intrinsic cellular regulation. Methods: In this study, we designed a cisplatin prodrug-loaded manganese-deposited iron oxide nanoplatform (Pt-FMO) to trigger intracellular cascade reactions that lead to generation of reactive oxygen species (ROS) to enhance ferroptotic effect. The Pt-FMO causes the tumor microenvironment responsive to release manganese, iron ions and Pt-drugs. As manganese is an element that is able to catalyze the Fenton reaction more effectively than iron, coupled with the Pt-drugs that can promote generation of H2O2 in cells, the Pt-FMO is expected to significantly strengthen catalysis of the Fenton reaction, which favors the ferroptotic effect. Moreover, the Pt-drugs will eventually function as cisplatin. Thus, Pt-FMO is an ideal candidate for tumor ferroptotic combined with apoptotic treatment. Results:In vivo results demonstrated that, at a dosage of only 8.89% Pt content, Pt-FMO is able to achieve a similar treatment effect as cisplatin. Hence, Pt-FMO exhibited significantly lower systemic toxicity compared to cisplatin. Additionally, Pt-FMO exhibits effective T2 -weighted MRI enhancement for tumor imaging. Conclusion: The Pt-FMO nanoplatform is designed to introduce mutual beneficial cascade reactions for promoting ferroptosis and apoptosis in combination with tumor MRI. The Pt-FMO system, which causes ferroptosis combined with apoptosis, can efficiently induce tumor cell death.

MOFs-Derived Fe-N Codoped Carbon Nanoparticles as O2-Evolving Reactor and ROS Generator for CDT/PDT/PTT Synergistic Treatment of Tumors

Metal-organic frameworks (MOFs) derivatives had been widely explored in electronic and environmental fields, but rarely evaluated in the biomedical applications. Herein, Fe-N codoped carbon (FeNC) nanoparticles were synthesized and characterized via facile pyrolysis of precursor ZIF-8 (Fe/Zn) nanoparticles, and their potential applications in tumor therapy were assessed in this investigation both in vitro and in vivo. After PAA (sodium polyacrylate) modification, the FeNC@PAA nanoparticles were able to initiate a Fe-based Fenton-like reaction to generate ·OH and O₂ for chemodynamic therapy (CDT) and O₂ evolution. Meanwhile, the porphyrin-like metal center in the FeNC@PAA nanoparticles could be used as a photosensitizer for photodynamic therapy (PDT) of tumors, which could be enhanced by O₂ generated in CDT. Furthermore, the FeNC@PAA nanoparticles were also found to be effective in photothermal therapy (PTT) with a photothermal conversion efficiency of 29.15%, owing to a high absorbance in the near-infrared region (NIR). In conclusion, the synthesized FeNC@PAA nanoparticles exhibited promising applications in O₂ evolution and CDT/PDT/PTT synergistic treatment of tumors.

Multienzyme-Mimic Ultrafine Alloyed Nanoparticles in Metal Organic Frameworks for Enhanced Chemodynamic Therapy

Nanozyme-based chemodynamic therapy (CDT) has emerged as an effective cancer treatment because of its low side effects and without the requirement of exogenous energy. The therapeutic effect of CDT highlights the pivotal importance of active sites, H₂ O₂ supplement and the glutathione (GSH) depletion of a nanozyme. The construction of a single kind of catalyst with multiple functions for the enhanced CDT is still a big challenge. In this work, seven types of bimetallic nanoparticles are synthesized using a metal-organic framework (MOF) as a stable host instead of a Fenton or Fenton-like ions supplier. Among them, Cu-Pd@MIL-101 with an alloy loading of 9.5 wt% modified by PEG (9.5% CPMP) is found to exhibit the highest peroxidase (POD) like activity combined with a superoxide dismutase (SOD) mimic activity and the function of GSH depletion. The in vivo results suggest that the stable and ultrafine nanoparticles possess favorable CDT effect for tumor and good biosafety as well as biocompatibility. This work has provided a credible strategy to construct nanozymes with an excellent activity and may pave a new way for the design of enhanced tumor CDT treatment.

Tumor-Specific Activatable Nanocarriers with Gas-Generation and Signal Amplification Capabilities for Tumor Theranostics

Multifunctional nanotheranostics are typically designed by integrating multiple functional components. This approach not only complicates the preparation process but also hinders any bioapplication due to the potential toxic effects when each component is metabolized. Here, we report a safe, biodegradable, and tumor-specific nanocarrier that, once activated by the acidic tumor microenvironment (TME), has diagnostic and therapeutic functions suitable for tumor theranostics. Our nanocarrier is composed of biomineralized manganese carbonate (BMC) nanoparticles (NPs) that readily decompose to release Mn²⁺ ions and CO₂ gas in the acidic TME due to its intrinsic pH-dependent solubility. Mn²⁺ and CO₂ release permits magnetic resonance and ultrasound imaging of tumors, respectively. These NPs can be loaded with the anticancer drug doxorubicin (DOX): BMC-DOX has high tumor inhibition effects both in vitro and in vivo due to combined Mn²⁺-mediated chemodynamic therapy and DOX-induced chemotherapy. This tumor-specific actuating nanocarrier might be a promising candidate for clinical translation.

External and Internal Stimuli-Responsive Metallic Nanotherapeutics for Enhanced Anticancer Therapy

Therapeutic, diagnostic, and imaging approaches based on nanotechnology offer distinct advantages in cancer treatment. Various nanotherapeutics have been presented as potential alternatives to traditional anticancer therapies such as chemotherapy, radiotherapy, and surgical intervention. Notably, the advantage of nanotherapeutics is mainly attributable to their accumulation and targeting ability toward cancer cells, multiple drug-carrying abilities, combined therapies, and imaging approaches. To date, numerous nanoparticle formulations have been developed for anticancer therapy and among them, metallic nanotherapeutics reportedly demonstrate promising cancer therapeutic and diagnostic efficiencies owing to their dense surface functionalization ability, uniform size distribution, and shape-dependent optical responses, easy and cost-effective synthesis procedure, and multiple anti-cancer effects. Metallic nanotherapeutics can remodel the tumor microenvironment by changing unfavorable therapeutic conditions into therapeutically accessible ones with the help of different stimuli, including light, heat, ultrasound, an alternative magnetic field, redox, and reactive oxygen species. The combination of metallic nanotherapeutics with both external and internal stimuli can be used to trigger the on-demand release of therapeutic molecules, augmenting the therapeutic efficacies of anticancer therapies such as photothermal therapy, photodynamic therapy, magnetic hyperthermia, sonodynamic therapy, chemodynamic therapy, and immunotherapy. In this review, we have summarized the role of different metallic nanotherapeutics in anti-cancer therapy, as well as their combinational effects with multiple stimuli for enhanced anticancer therapy.

Photosensitizer Nanoparticles Boost Photodynamic Therapy for Pancreatic Cancer Treatment

Patients with pancreatic cancer (PCa) have a poor prognosis apart from the few suitable for surgery. Photodynamic therapy (PDT) is a minimally invasive treatment modality whose efficacy and safety in treating unresectable localized PCa have been corroborated in clinic. Yet, it suffers from certain limitations during clinical exploitation, including insufficient photosensitizers (PSs) delivery, tumor-oxygenation dependency, and treatment escape of aggressive tumors. To overcome these obstacles, an increasing number of researchers are currently on a quest to develop photosensitizer nanoparticles (NPs) by the use of a variety of nanocarrier systems to improve cellular uptake and biodistribution of photosensitizers. Encapsulation of PSs with NPs endows them significantly higher accumulation within PCa tumors due to the increased solubility and stability in blood circulation. A number of approaches have been explored to produce NPs co-delivering multi-agents affording PDT-based synergistic therapies for improved response rates and durability of response after treatment. This review provides an overview of available data regarding the design, methodology, and oncological outcome of the innovative NPs-based PDT of PCa.

Tumor cell-activated "Sustainable ROS Generator" with homogeneous intratumoral distribution property for improved anti-tumor therapy

Photodynamic therapy (PDT) holds a number of advantages for tumor therapy. However, its therapeutic efficiency is limited by non-sustainable reactive oxygen species (ROS) generation and heterogeneous distribution of photosensitizer (PS) in tumor. Herein, a "Sustainable ROS Generator" (SRG) is developed for efficient antitumor therapy. Methods: SRG was prepared by encapsulating small-sized Mn₃O₄-Ce6 nanoparticles (MC) into dendritic mesoporous silica nanoparticles (DMSNs) and then enveloped with hyaluronic acid (HA). Due to the high concentration of HAase in tumor tissue, the small-sized MC could be released from DMSNs and homogeneously distributed in whole tumor. Then, the released MC would be uptaken by tumor cells and degraded by high levels of intracellular glutathione (GSH), disrupting intracellular redox homeostasis. More importantly, the released Ce6 could efficiently generate singlet oxygen (¹O₂) under laser irradiation until the tissue oxygen was exhausted, and the manganese ion (Mn²⁺) generated by degraded MC would then convert the low toxic by-product (H₂O₂) of PDT to the most harmful ROS (·OH) for sustainable and recyclable ROS generation. Results: MC could be homogeneously distributed in whole tumor and significantly reduced the level of intracellular GSH. At 2 h after PDT, obvious intracellular ROS production was still observed. Moreover, during oxygen recovery in tumor tissue, ·OH could be continuously produced, and the nanosystem could induce 82% of cell death comparing with 30% of cell death induced by free Ce6. For in vivo PDT, SRG achieved a complete inhibition on tumor growth. Conclusion: Based on these findings, we conclude that the designed SRG could induce sustainable ROS generation, homogeneous intratumoral distribution and intracellular redox homeostasis disruption, presenting an efficient strategy for enhanced ROS-mediated anti-tumor therapy.

NIR-triggered biodegradable MOF-coated upconversion nanoparticles for synergetic chemodynamic/photodynamic therapy with enhanced efficacy

The generation of reactive oxygen species (ROS) is often limited by the overexpression of glutathione (GSH) in the tumor microenvironment (TME) and the penetration depth of visible light.