A dual-catalytic nanoreactor for synergistic chemodynamic-starvation therapy toward tumor metastasis suppression

Photodynamic therapy with NIR-II probes: review on state-of-the-art tools and strategies

In 2022 10% of the world's population was aged 65+, and by 2100 this segment is expected to hit 25%. These demographic changes place considerable pressure over healthcare systems worldwide, which results in an urgent need for accurate, inexpensive and non-invasive ways to treat cancers, a family of diseases correlated with age. Among the therapeutic tools that gained important attention in this context, photodynamic therapies (PDT), which use photosensitizers to produce cytotoxic substances for selectively destroying tumor cells and tissues under light irradiation, profile as important players for next-generation nanomedicine. However, the development of clinical applications is progressing at slow pace, due to still pending bottlenecks, such as the limited tissue penetration of the excitation light, and insufficient targeting performance of the therapeutic probes to fully avoid damage to normal cells and tissues. The penetration depth of long-wavelength near infrared (NIR) light is significantly higher than that of short-wavelength UV and visible light, and thus NIR light in the second window (NIR-II) is acknowledged as the preferred phototherapeutic means for eliminating deep-seated tumors, given the higher maximum permissible exposure, reduced phototoxicity and low autofluorescence, among others. Upon collective multidisciplinary efforts of experts in materials science, medicine and biology, multifunctional NIR-II inorganic or organic photosensitizers have been widely developed. This review overviews the current state-of-the art on NIR-II-activated photosensitizers and their applications for the treatment of deep tumors. We also place focus on recent efforts that combine NIR-II activated PDT with other complementary therapeutic routes such as photothermal therapy, chemotherapy, immunotherapy, starvation, and gas therapies. Finally, we discuss still pending challenges and problems of PDT and provide a series of perspectives that we find useful for further extending the state-of-the art on NIR-II-triggered PDT.

Focused starvation of tumor cells using glucose oxidase: A comprehensive review

Starvation therapy targets the high metabolic demand of tumor cells. It primarily leans over the consumption of intracellular glucose and simultaneous blockade of alternative metabolic pathways. The strategy involves the use of glucose oxidase (GOx) for catalyzing the conversion of glucose into gluconic acid and hydrogen peroxide. Under these conditions, metabolic re-programming of tumor cells enables the utilization of substrates such as amino acids, fatty acids and lipids. This can be overcome by co-administration of chemo-, photo- and immuno-therapeutics together with glucose oxidase. Targeted delivery of glucose oxidase at tumor site can be enabled with the use of nanoformulations. In this review, we highlight that the outcomes of starvation therapy can be improved using rationally developed nano-formulations. It is possible to load synergistically acting bioactives in these formulations and deliver in site-specific manner and hence achieve the elimination of tumors cells with greater efficacy.

Spatially Confined Nanoreactors Designed for Biological Applications

The applications of nanoreactors in biology are becoming increasingly significant and prominent. Specifically, nanoreactors with spatially confined, due to their exquisite design that effectively limits the spatial range of biomolecules, attracted widespread attention. The main advantage of this structure is designed to improve reaction selectivity and efficiency by accumulating reactants and catalysts within the chambers, thus increasing the frequency of collisions between reactants. Herein, the recent progress in the synthesis of spatially confined nanoreactors and their biological applications is summarized, covering various kinds of nanoreactors, including porous inorganic materials, porous crystalline materials with organic components and self-assembled polymers to construct nanoreactors. These design principles underscore how precise reaction control could be achieved by adjusting the structure and composition of the nanoreactors to create spatial confined. Furthermore, various applications of spatially confined nanoreactors are demonstrated in the biological fields, such as biocatalysis, molecular detection, drug delivery, and cancer therapy. These applications showcase the potential prospects of spatially confined nanoreactors, offering robust guidance for future research and innovation.

CeO2 and Glucose Oxidase Co-Enriched Ti3C2Tx MXene for Hyperthermia-Augmented Nanocatalytic Cancer Therapy

Foreseen as foundational in forthcoming oncology interventions are multimodal therapeutic systems. Nevertheless, the tumor microenvironment (TME), marked by heightened glucose levels, hypoxia, and scant concentrations of endogenous hydrogen peroxide could potentially impair their effectiveness. In this research, two-dimensional (2D) Ti3C2 MXene nanosheets are engineered with CeO2 nanozymes and glucose oxidase (GOD), optimizing them for TME, specifically targeting cancer therapy. Following our therapeutic design, CeO2 nanozymes, embodying both peroxidase-like and catalase-like characteristics, enable transformation of H2O2 into hydroxyl radicals for catalytic therapy while also producing oxygen to mitigate hypoxia. Concurrently, GOD metabolizes glucose, thereby augmenting H2O2 levels and disrupting the intracellular energy supply. When subjected to a near-infrared laser, 2D Ti3C2 MXene accomplishes photothermal therapy (PTT) and photodynamic therapy (PDT), additionally amplifying cascade catalytic treatment via thermal enhancement. Empirical evidence demonstrates robust tumor suppression both in vitro and in vivo by the CeO2/Ti3C2-PEG-GOD nanocomposite. Consequently, this integrated approach, which combines PTT/PDT and enzymatic catalysis, could offer a valuable blueprint for the development of advanced oncology therapies.

A multivalent polyphenol-metal-nanoplatform for cascade amplified chemo-chemodynamic therapy

Chemodynamic therapy (CDT), as an emerging therapeutic strategy, kills cancer cells by converting intracellular hydrogen peroxide (H2O2) into cytotoxic oxidizing hydroxyl radicals (⋅OH). However, the therapeutic efficiency of CDT is compromised due to the insufficient endogenous H2O2 and metal catalysts in tumor cells. The use of multivalent polyphenols with multiple hydroxyl functions provides a facile yet robust means for efficient CDT augmentation. For this purpose, we reported herein the construction of polyphenol-metal nanoparticles (NPs) via a phenol-metal coordination strategy. The uniqueness of this study is the preparation of only one polymer construct with multivalency that can afford various supramolecular interactions for simultaneous "one-pot" loading of different therapeutic species, i.e., doxorubicin (DOX), glucose oxidases (GOD), and Fe3+ and further co-self-assembly into a stabilized nanomedicine for cascade amplified chemo-chemodynamic therapy. Specifically, the tumor intracellular acidic pH-triggered DOX release could serve for chemotherapy as well as enhance the intracellular H2O2 level. Together with the extra H2O2 and gluconic acid produced by the GOD-triggered glucose consumption, DOX@POAD-Fe@GOD NPs promoted Fe3+participation in the Fe-mediated Fenton reaction for cascade amplified chemo-chemodynamic therapy. Notably, this formulation displayed a greater anti-tumor effect with a tumor inhibition ratio 1.6-fold higher than that of free DOX in a BALB/c mice model bearing 4T1 tumors. Overall, the multivalent polyphenol-metal nanoplatform developed herein integrates chemotherapy, starvation therapy, and CDT for synergistic enhanced anticancer efficiency, which shows great potential for clinical translations. STATEMENT OF SIGNIFICANCE: Chemodynamic therapy (CDT) generally suffers from compromised therapeutic efficiency due to insufficient endogenous H2O2 and metal catalysts in tumor cells. To develop a facile yet robust strategy for efficient CDT augmentation, we reported herein construction of a multivalent polyphenol-metal nanoplatform, DOX@POAD-Fe@GOD nanoparticles (NPs) via a phenol-metal coordination strategy. This nanoplatform integrates multiple supramolecular dynamic interactions not only for simultaneously safe encapsulation of doxorubicin (DOX), Fe3+, and glucose oxidases (GOD), but also for cascade amplified chemo-chemodynamic therapy. Specifically, the intracellular acidic pH-triggered dissociation of DOX@POAD-Fe@GOD NPs promoted the release of Fe3+, DOX, and GOD for significantly increased ROS levels that can accelerate Fenton reactions for cascaded chemotherapy, starvation therapy, and CDT with amplified antitumor efficiency in vivo.

Cascaded Nanozyme with In Situ Enhanced Photothermal Capacity for Tumor-Specific and Self-Replenishing Cancer Therapy

Reactive oxygen species (ROS)-involved tumor therapeutic strategy, chemodynamic therapy (CDT), has attracted extensive research interest in the scientific community. However, the therapeutic effect of CDT is insufficient and unsustainable owing to the limited endogenous H2 O2 level in the tumor microenvironment. Here, peroxidase (POD)-like RuTe2 nanozyme with the immobilization of glucose oxidase (GOx) and allochroic 3,3',5,5'-tetramethylbenzidine (TMB) molecule have been synthesized to construct RuTe2 -GOx-TMB nanoreactors (RGT NRs) as cascade reaction systems for tumor-specific and self-replenishing cancer therapy. GOx in sequential nanocatalysts can effectively deplete glucose in tumor cells. Meanwhile, a sustainable supply of H2 O2 for subsequent Fenton-like reactions catalyzed by RuTe2 nanozyme is achieved in response to the mild acidic tumor microenvironment. Through this cascade reaction, highly toxic hydroxyl radicals (·OH) are produced, which can further oxidize TMB to trigger tumor-specific "turn-on" photothermal therapy (PTT). In addition, PTT and massive ROS can stimulate the tumor immune microenvironment and activate the systematic anti-tumor immune responses, exerting a notable effect on hindering tumor recurrence and metastasis. This study paves a promising paradigm for synergistic starvation therapy, PTT, and CDT cancer therapy with high efficiency.

Degradable Fe3O4-based nanocomposite for cascade reaction-enhanced anti-tumor therapy

Cascade catalytic therapy has been recognized as a promising cancer treatment strategy, which is due in part to the induced tumor apoptosis when converting intratumoral hydrogen peroxide (H2O2) into highly toxic hydroxyl radicals (˙OH) based on the Fenton or Fenton-like reactions. Moreover this is driven by the efficient catalysis of glucose oxidization associated with starving therapy. The natural glucose oxidase (GO x ), recognized as a "star" enzyme catalyst involved in cancer treatment, can specially and efficiently catalyze the glucose oxidization into gluconic acid and H2O2. Herein, pH-responsive biodegradable cascade therapeutic nanocomposites (Fe3O4/GO x -PLGA) with dual enzymatic catalytic features were designed to respond to the tumor microenvironment (TME) and to catalyze the cascade reaction (glucose oxidation and Fenton-like reaction) for inducing oxidase stress. The GO x -motivated oxidation reaction could effectively consume intratumoral glucose to produce H2O2 for starvation therapy and the enriched H2O2 was subsequently converted into highly toxic ˙OH by a Fe3O4-mediated Fenton-like reaction for chemodynamic therapy (CDT). In addition, the acidity amplification owing to the generation of gluconic acid will in turn accelerate the degradation of the nanocomposite and initiate the Fe3O4-H2O2 reaction for enhancing CDT. The resultant cooperative cancer therapy was proven to provide highly efficient tumor inhibition on HeLa cells with minimal systemic toxicity. This cascade catalytic Fenton nanocomposite might provide a promising strategy for efficient cancer therapy.

Ferrocene and glucose oxidase-installed multifunctional hydrogel reactors for local cancer therapy

A hyaluronic acid (HA)-based one-pot hydrogel reactor with single syringe injection and immediate gelation was developed for starvation therapy (ST), chemodynamic therapy (CDT), ferroptosis, and photothermal therapy (PTT) against breast cancer. A rheologically tuned hydrogel network, composed of HA-phenylboronic acid (HP) and HA-dopamine (HD), was designed by introducing a boronate ester linkage (phenylboronic acid-dopamine interaction) and polydopamine bond (pH control). Ferrocene (Fc)-conjugated HP (Fc-HP) was synthesized to achieve ferroptosis, Fenton reaction-involved toxic hydroxyl radical (^•OH) generation, and photothermal ablation in cancer therapy. Glucose oxidase (GOx) was entrapped in the pH-modulated Fc-HP (Fc-HP°)/HD hydrogel network for converting intracellular glucose to H₂O₂ to enable its own supply. The GOx/Fc combination-installed hydrogel reactor system can provide sustained ST/CDT/PTT functions along with ferroptosis. Injection of Fc-HP°/HD/GOx hydrogel with single-syringe injectability, shear-thinning feature, and self-healing capability offered a slow biodegradation rate and high safety profiles. Peritumorally injected Fc-HP°/HD/GOx hydrogel also efficiently suppressed the growth of breast cancer based on multifunctional therapeutic approaches with reduced dosing frequency. Hyperthermia induced by near-infrared (NIR) laser absorption may amplify the therapeutic effects of free radicals. It is expected that this Fc-HP°/HD/GOx hydrogel system can be applied to local cancer therapy with high efficacy and safety profiles.

Glucose Metabolism Intervention-Facilitated Nanomedicine Therapy

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

Research Progress on Improving the Efficiency of CDT by Exacerbating Tumor Acidification

In recent years, chemodynamic therapy (CDT) has received extensive attention as a novel means of cancer treatment. The CDT agents can exert Fenton and Fenton-like reactions in the acidic tumor microenvironment (TME), converting hydrogen peroxide (H₂O₂) into highly toxic hydroxyl radicals (·OH). However, the pH of TME, as an essential factor in the Fenton reaction, does not catalyze the reaction effectively, hindering its efficiency, which poses a significant challenge for the future clinical application of CDT. Therefore, this paper reviews various strategies to enhance the antitumor properties of nanomaterials by modulating tumor acidity. Ultimately, the performance of CDT can be further improved by inducing strong oxidative stress to produce sufficient ·OH. In this paper, the various acidification pathways and proton pumps with potential acidification functions are mainly discussed, such as catalytic enzymes, exogenous acids, CAIX, MCT, NHE, NBCn1, etc. The problems, opportunities, and challenges of CDT in the cancer field are also discussed, thereby providing new insights for the design of nanomaterials and laying the foundation for their future clinical applications.

Strategies for enhancing cancer chemodynamic therapy performance

Chemodynamic therapy (CDT) has emerged to be a frontrunner amongst reactive oxygen species-based cancer treatment modalities. CDT utilizes endogenous H2O2 in tumor microenvironment (TME) to produce cytotoxic hydroxyl radicals (•OH) via Fenton or Fenton-like reactions. While possessing advantages such as tumor specificity, no need of external stimuli, and low side effects, practical applications of CDT are still impeded owing to the heterogeneity, complexity, and reductive environment of TME. Over the past couple of years, strategies to enhance CDT for efficient tumor regression are in rapid development in synergy with the growth of nanomedicine. In this review, we initially outline the fundamental understanding of Fenton and Fenton-like reactions and their relationship with CDT. Subsequently, the development in the design of nanosystems for CDT is highlighted in a general manner. Furthermore, recent advancement of the strategies to augment Fenton reactions in TME for enhanced CDT is discussed in detail. Finally, perspectives toward the future development of CDT for better therapeutic outcome are presented. This review is expected to draw attention for collaborative research on CDT in the best interest of its future clinical applications.

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.

Construction of pH-responsive nanocarriers in combination with ferroptosis and chemotherapy for treatment of hepatocellular carcinoma

Background

Chemotherapy is widely used to treat hepatocellular carcinoma (HCC). Although sorafenib (SO) is the only chemotherapy drug approved by FDA for treatment of HCC, it is associated with several disadvantages including low water solubility, low bioavailability, lack of targeting and easily causes systemic toxicity. In recent years, nanocarriers have shown promise in drug delivery to effectively solve these problems. Herein, we used SO-loaded nanocarriers to overcome the defects of chemotherapy during treatment of HCC. Specifically, we encapsulated pH-sensitive hollow mesoporous Prussian blue nanoparticles (HMPB) with SO (an inhibitor of multi-kinase and accelerant of ferroptosis) to act as carriers and facilitate drug release. We also coated its surface with a layer of pH-responsive chitosan (CS) to block the drug and increase biocompatibility. Finally, we successfully constructed HP/SO/CS nanocomposites for targeted delivery of chemotherapeutic drugs, with the aim of initiating chemotherapy and ferroptosis for dual treatment of tumors. In vitro and in vivo experiments were performed for evaluation of the nanocomposites’ anti-tumor efficacy by using liver cancer cells and mice, respectively.

Results

The nanocomposites specifically targeted tumor cells through enhancing permeability and retention (EPR) effect. Results from in vitro experiments showed that the nanocarriers not only promoted cell apoptosis and reduced the number of cells for chemotherapy, but also promoted accumulation of reactive oxygen species (ROSs). In vivo experiments showed that mice in the nanocomposite-treated group exhibited the smallest tumor sizes and body weights, with no obvious damage to normal tissues and organs.

Conclusion

Taken together, these findings indicated that nanocarriers had an effective inhibitory effect on HCC cells. This safe and multifunctional treatment model was a valuable option for the treatment of HCC, as well as other cancers.

Graphical Abstract

Rational Construction of a Triphenylphosphine-Modified Tetra-nuclear Cu(I) Coordinated Cluster for Enhanced Chemodynamic Therapy

A triphenylphosphine-modified tetra-nuclear Cu(I) coordinated cluster was constructed for enhanced Chemodynamic Therapy (CDT) by increasing the metal centers. After inside human bladder cancer (T24) cells, a larger number of copper...

Component-optimized chemo-dynamic nanoagent for enhanced tumour cell-selective chemo-dynamic therapy with minimal side effect in glioma mouse model

Although CuO-deposited bovine serum albumin (CuO-BSA) and glucose oxidase (Gox) were combined to achieve H2O2 self-supplied chemo-dynamic therapy (CDT) and glucose consumption-based starvation therapy, the uses of copper and Gox...

Multifunctional FeS2@SRF@BSA nanoplatform for chemo-combined photothermal enhanced photodynamic/chemodynamic combination therapy

Combination therapy has been widely studied due to its promising applications in tumor therapy. However, a sophisticated nanoplatform and sequential irradiation with different laser sources for phototherapy complicate the treatment process. Unlike the integration of therapeutic agents, we report a FeS₂@SRF@BSA nanoplatform for the combination of chemo-combined photothermal therapy (PTT) enhanced photodynamic therapy (PDT) and chemodynamic therapy (CDT) to achieve an "all-in-one" therapeutic agent. Ultrasmall FeS₂ nanoparticles (NPs) with a size of 7 nm exhibited higher Fenton reaction rates due to their large specific surface areas. A photodynamic reaction could be triggered and could generate ¹O₂ to achieve PDT under 808 nm irradiation. FeS₂ NPs also exhibited the desired photothermal properties under the same wavelength of the laser. The Fenton reaction and photodynamic reaction were both significantly improved to accumulate more reactive oxygen species (ROS) with an increase of temperature under laser irradiation. Besides, loading of the chemotherapeutic drug sorafenib (SRF) further improved the efficacy of tumor treatment. To realize long blood circulation, bovine serum albumin (BSA) was used as a carrier to encapsulate FeS₂ NPs and SRF, remarkably improving the biocompatibility and tumor enrichment ability of the nanomaterials. Additionally, the tumors on mice treated with FeS₂@SRF@BSA almost disappeared under 808 nm irradiation. To sum up, FeS₂@SRF@BSA NPs possess good biocompatibility, stability, and sufficient therapeutic efficacy in combination therapy for cancer treatment. Our study pointed out a smart design of the nanoplatform as a multifunctional therapeutic agent for combination cancer therapy in the near future.