Synthesis of CaCO3-Based Nanomedicine for Enhanced Sonodynamic Therapy via Amplification of Tumor Oxidative Stress

Cellular defense system-destroying nanoparticles as a platform for enhanced chemotherapy against drug-resistant cancer

Cellular defense system represented by glutathione (GSH) greatly weakens the outcomes of cancer therapy by antioxidation and detoxification. GSH depletion has been proved to be an effective way to enhance the efficacy of reactive oxygen species (ROS)-based therapies and chemotherapy. However, the existing strategies of GSH depletion still face the problems of unclear biosafety and high complexity of multicomponent co-delivery. In this study, we developed a GSH-depleting carrier platform based on disulfide-bridged mesoporous organosilica nanoparticles (MONs) to destroy the cellular defense system for cancer therapy. Responding to the high level of GSH in cancer cells, the disulfide bonds in the framework of MONs could be broken and consumed substantial GSH at the same time. Moreover, this process also promoted the degradation of MONs. In order to evaluate the effect of this platform in cancer therapy, chemotherapeutic drug cisplatin was loaded into MONs (Pt@MONs) to treat drug-resistant non-small cell lung cancer. In vitro and in vivo results indicated that Pt@MONs efficiently triggered GSH depletion, promoted platinum-DNA adduct formation, and induced cell apoptosis, resulting in significant tumor growth inhibition without marked toxicity. Taken together, the cellular defense system-destroying nanoparticles provide a promising platform for enhanced cancer therapy.

A nanoplatform to boost multi-phases of cancer-immunity-cycle for enhancing immunotherapy

The failure of any phase in continuous multi-link immune response process can cause unsatisfactory outcomes, which might be improved by all-cancer-immunity-cycle boosted strategy. Herein, a nanoplatform Mn/CaCO₃@PL/SLC is developed, which is based on palmitoyl ascorbate (PA)-liposome (PL) loaded with Mn-doped CaCO₃ nanoparticles (Mn/CaCO₃ NPs) and carbonic anhydrase (CAIX) inhibitor SLC-0111. The nanoplatform comprehensively amplifies all immune stages including tumor-associated antigens (TAAs) release and presentation, T cells activation and infiltration, as well as tumor cells destruction. In detail, Mn-triggered lipid peroxidation facilitates TAAs release and subsequent T cells activation to initiate immunity cycle. Additionally, SLC-0111 and PA amplify the infiltration and tumor killing activity of these effector T cells. The former polarizes the immunosuppressive tumor microenvironment to an immune-active phenotype and the latter enhances the function of tumor-infiltrating T lymphocytes. Importantly, Mn augments the all-immunity-cycle by promoting cGAS-STING pathway activation. In summary, the Mn/CaCO₃@PL/SLC nanoplatform is verified to boost anti-tumor immunity and achieve outstanding immunotherapeutic effects in eradicating tumor and preventing tumor metastasis. Such an all-cancer-immunity-cycle boosted strategy is meaningful for antitumor immunotherapy.

SnFe2O4 Nanozyme Based TME Improvement System for Anti-Cancer Combination Thermoradiotherapy

High doses of radiotherapy (RT) are associated with resistance induction. Therefore, highly selective and controllable radiosensitizers are urgently needed. To address this issue, we developed a tin ferrite (SFO)-based tumor microenvironment (TME)-improved system (SIS) that can be used in combination with low-dose radiation. The SIS was delivered via intratumoral injection directly to the tumor site, where it was stored as a ration depot. Due to the photothermal properties of SFO, SIS steadily dissolved under near-infrared (NIR) laser irradiation. Simultaneously, the dual glutathione oxidase (GSH-OXD) and catalase (CAT) activities of the SFO nanozyme significantly lowered the content of GSH in tumor tissues and efficiently catalyzed the conversion of intracellular hydrogen peroxide to produce a large amount of oxygen (O₂) for intracellular redox homeostasis disruption, thus reducing radiotherapy resistance. Our in vivo and in vitro studies suggested that combining the SIS and NIR irradiation with RT (2Gy) significantly reduced tumor proliferation without side effects such as inflammation. To conclude, this study revealed that SFO-based nanozymes show great promise as a catalytic, radiosensitizing anti-tumor therapy.

A flowerlike FePt/MnO2/GOx-based cascade nanoreactor with sustainable O2 supply for synergistic starvation-chemodynamic anticancer therapy

The development of versatile nanotheranostic agents has received increasing interest in cancer treatment. Herein, in this study, we rationally designed and prepared a novel flowerlike multifunctional cascade nanoreactor, BSA-GOx@MnO2@FePt (BGMFP), by integrating glucose oxidase (GOx), manganese dioxide (MnO2) and FePt for synergetic cancer treatment with satisfying therapeutic efficiency. In an acidic environment, intratumoral H2O2 could be decomposed to O2 to accelerate the consumption of glucose catalyzed by GOx to induce cancer starvation. Moreover, the accumulation of gluconic acid and H2O2 generated along with the consumption of glucose would in turn promote the catalytic efficiency of MnO2 and boost O2 evolution, which could enhance the efficiency of starvation therapy. Moreover, FePt as an excellent Fenton agent could simultaneously convert H2O2 to the toxic hydroxyl radical (˙OH), subsequently resulting in amplified intracellular oxidative stress and cell apoptosis. Therefore, BGMFP could catalyze a cascade of intracellular biochemical reactions and optimize the unique properties of MnO2, GOx and FePt via mutual promotion of each other to realize O2 supply, chemodynamic therapy (CDT) and starvation therapy. The anticancer results in vitro and in vivo demonstrated that BGMFP possessed remarkable tumor inhibition capacity through enhancing the starvation therapy and CDT. It is appreciated that BGMFP could be a promising platform for synergetic cancer treatment.

Nanosonosensitizers With Ultrasound-Induced Reactive Oxygen Species Generation for Cancer Sonodynamic Immunotherapy

Immunotherapy is a promising therapeutic strategy for cancer, while it has been demonstrated to encounter the issues of low immune responses and underlying immune-related adverse events. The sonodynamic therapy (SDT) that utilizes sonosensitizers to produce reactive oxygen species (ROS) triggered by ultrasound (US) stimulation can be used to ablate tumors, which also leads to the induction of immunogenic cell death (ICD), thus achieving SDT-induced immunotherapy. Further combination of SDT with immunotherapy is able to afford enhanced antitumor immunity for tumor regression. In this mini review, we summarize the recent development of nanosonosensitizers with US-induced ROS generation for cancer SDT immunotherapy. The uses of nanosonosensitizers to achieve SDT-induced immunotherapy, combinational therapy of SDT with immunotherapy, and combinational therapy of SDT with multiple immunotherapies are briefly introduced. Furthermore, the current concerns and perspectives for the development and further clinical applications of these nanosonosensitizers for SDT-combined immunotherapy of cancer are discussed.

Advanced biotechnology-assisted precise sonodynamic therapy

Despite significant advances, the therapeutic impact of photodynamic therapy is still substantially hampered by the restricted penetration depth of light and the reactive oxygen species (ROS)-mediated toxicity, which is impeded by the shorter effective half-life and radius of ROS produced during treatment. Sonodynamic therapy (SDT), on the other hand, provides unrivalled benefits in deep-seated tumour ablation due to its deep penetration depth and not totally ROS-dependent toxicity, exhibiting enormous preclinical and clinical potential. In this tutorial review, we highlight imaging-guided precise SDT, which allows choosing the best treatment option and monitoring the therapy response in real-time, as well as recent clinical trials based on SDT. Aside from that, the subtle design strategies of sonosensitizers based on tumour environment shaping and rational structure modification, as well as SDT combination treatment (chemotherapy, chemodynamic therapy, photodynamic therapy, photothermal therapy, gas therapy and immunotherapy), aimed at a more effective treatment outcome, are summarized. Finally, we discussed the future of SDT for personalized cancer and other disease treatments.

Biodegradable Upconversion Nanoparticles Induce Pyroptosis for Cancer Immunotherapy

Pyroptosis, which is a mode of programmed cell death, has proven effective for cancer therapy. However, efficient pyroptosis inducers for tumor treatment are limited. This study proposes biodegradable K₃ZrF₇:Yb/Er upconversion nanoparticles (ZrNPs) as pyroptosis inducers for cancer immunotherapy. ZrNPs, which are similar to ion reservoirs, can be dissolved inside cancer cells and release high amounts of K⁺ and [ZrF₇]^3- ions, resulting a surge in intracellular osmolarity and homeostasis imbalance. This further induces an increase in reactive oxygen species (ROS), caspase-1 protein activation, gasdermin D (GSDMD) cleavage, and interleukin-1β (IL-1β) maturity, and results in cytolysis. In vivo tests confirm that ZrNPs-induced pyroptosis exhibits superior antitumor immunity activity confirmed by enhanced dendritic cells (DCs) maturity and frequency of effector-memory T cells, as well as observably inhibiting tumor growth and pulmonary metastasis. This work is believed to extend the biomedical applications of upconversion nanomaterials and deepen the understanding of intrinsic immunomodulatory activity of nanomaterials.

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

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

Manganese carbonate nanoparticles-mediated mitochondrial dysfunction for enhanced sonodynamic therapy

Sonodynamic therapy (SDT) has attracted widespread attention due to its non-invasiveness and deep tissue penetration. However, the development of efficient sonodynamic nanoplatforms to improve the therapeutic efficiency is still one of the main challenges of current research. In this work, a new type of sonosensitizer prepared by a simple method, manganese carbonate nanoparticles (MnCO3 NPs), is used for enhanced SDT. MnCO3 NPs could generate large amounts of 1O2 and •OH under ultrasound irradiation. At the same time, CO2 and Mn ions could be released in a weak acid environment due to the excellent degradability of MnCO3 NPs. The CO2 bubbles caused cell necrosis by ultrasonic cavitation and used for ultrasound imaging. And Mn ions activated the mitochondrial cell apoptosis pathway. In vivo experiments proved that this sonosensitizer with mitochondrial regulatory capacity showed high tumor inhibition rates for enhanced sonodynamic tumor therapy.

W-Doped TiO2 Nanorods for Multimode Tumor Eradication in Osteosarcoma Models under Single Ultrasound Irradiation

Sonosensitizers play crucial roles in the controlled production of reactive oxygen species (ROS) under ultrasound (US) irradiation with high tissue-penetration depth for noninvasive solid tumor therapy. It is desirable to fabricate structurally simple yet multifunctional sonosensitizers from ultrafine nanoparticles for ROS-based multimode therapy to overcome monomode limitations such as low ROS production yields and endogenous reductive glutathione (GSH) to ROS-based treatment resistance. We report the facile high-temperature solution synthesis of ultrafine W-doped TiO2 (W-TiO2) nanorods for exploration of their sonodynamic, chemodynamic, and GSH-depleting activities in sonodynamic-chemodynamic combination tumor therapy. We found that W5+ and W6+ ions doped in W-TiO2 nanorods play multiple roles in enhancing their ROS production. First, W doping narrows the band gap from 3.2 to 2.3 eV and introduces oxygen and Ti vacancies for enhancing their sonodynamic performance. Second, W5+ doping endows W-TiO2 nanorods with Fenton-like reaction activity to produce •OH from endogenous H2O2 in the tumor. Third, W6+ ions reduce endogenous GSH to glutathione disulfide (GSSG) and, in turn, form W5+ ions that further enhance their chemodynamic activity, which greatly modifies thae oxidation-reduction tumor microenvironment in the tumor. In vivo experiments display the excellent ability of W-TiO2 nanorods for enhanced tumor eradication in human osteosarcoma models under single US irradiation. Importantly, the ultrafine nanorod morphology facilitates rapid excretion from the body, displaying no significant systemic toxicity. Our work suggests that multivalent metal doping in ultrafine nanomaterials is an effective and simple strategy for the introduction of new functions for ROS-based multimode therapy.

Calcium Peroxide-Based Nanosystem with Cancer Microenvironment-Activated Capabilities for Imaging Guided Combination Therapy via Mitochondrial Ca2+ Overload and Chemotherapy

Mitochondria are the "power plant" of the cell, providing a constant source of energy, and are involved in a variety of intracellular signaling pathways. Among these pathways, Ca²⁺ homeostasis is closely related to the normal function of mitochondria. By destroying the Ca²⁺ steady state of mitochondria and disrupting their multiple cellular activities, tumor cell killing can be achieved. In addition, the presence of an intracellular oxidative stress state triggers the closure of cellular calcium channels, which leads to intracellular Ca²⁺ retention and enrichment. We designed a targeted and tumor microenvironment (TME)-responsive CaO₂-based nanosystem that can selectively target cancer cells for pH-controlled degradation and drug release, alter cellular physiological mechanisms by disrupting Ca²⁺ homeostasis in an artificial manner, and introduce mitochondrial Ca²⁺ excess-mediated apoptosis. Meanwhile, the production of Ca(OH)₂ will raise the pH of the microenvironment and subsequently promote the oxidation process of glutathione by H₂O₂ released from CaO₂ degradation, achieving the goal of remodeling TME. Moreover, calcium overload of tumor cells and calcification of tissues can both inhibit tumor growth and act as a contrast agent for computed tomography imaging.

Sub 5 nm Gd3+ -Hemoporfin Framework Nanodots for Augmented Sonodynamic Theranostics and Fast Renal Clearance

Metal-organic nanomaterials have emerged as promising therapeutic agents to produce reactive oxygen species (ROS) under ultrasound (US) or light irradiation for tumor treatments. However, their relatively large sizes (ranging from tens to hundreds of nanometers) usually lead to low ROS utilization and body metabolism, thus enlarging their long-term toxicity and low therapeutic effect. To solve these shortcomings, herein the ultrasmall Gd³⁺ -hemoporfin framework nanodots (GdHF-NDs， ≈5 nm) is reported as efficient nano-sonosensitizers. Compared with GdHF aggregation (GdHF-A, ≈400 nm), the ultrasmall GdHF-NDs generate 2.3-fold toxic ROS amount under similar conditions, due to shorter diffusion path and larger relative specific surface area. When the GdHF-NDs dispersion is introvenously injected into tumor-bearing mouse, they are accumulated within tumors to provide high magnetic resonance imaging (MRI) contrast. Under US irradiation, the GdHF-NDs achieve a better sonodynamic therapeutic efficacy for tumors, compared with that from GdHF-A. More importantly, owing to ultrasmall size, most of GdHF-NDs can be rapidly cleared through the renal pathway. Therefore, GdHF-NDs can be used as a biosafety and high-performance sonodynamic agent for cancer theranostics.

A Robust Narrow Bandgap Vanadium Tetrasulfide Sonosensitizer Optimized by Charge Separation Engineering for Enhanced Sonodynamic Cancer Therapy

The development and optimization of sonosensitizers for elevating intratumoral reactive oxygen species (ROS) are definitely appealing in current sonodynamic therapy (SDT). Given this, branched vanadium tetrasulfide (VS₄ ) nanodendrites with a narrower bandgap (compared with the most extensively explored sonosensitizers) are presented as a new source of sonosensitizer, which allows a more effortless separation of sono-triggered electron-hole pairs for ROS generation. Specifically, platinum (Pt) nanoparticles and endogenous high levels of glutathione (GSH) are rationally engineered to further optimize its sono-sensitized performance. As cocatalyst, Pt is conducive to trapping electrons, whereas GSH, as a natural hole-scavenger, tends to capture holes. Compared with the pristine VS₄ sonosensitizer, the GSH-Pt-VS₄ nanocomposite can greatly prolong the lifetime of the charge and confer a highly efficacious ROS production activity. Furthermore, such nanoplatforms are capable of reshaping tumor microenvironments to realize ROS overproduction, contributed by overcoming tumor hypoxia to improve SDT-triggered singlet oxygen production, catalyzing endogenic hydrogen peroxide into destructive hydroxyl radicals for chemodynamic therapy, and depleting GSH to amplify intratumoral oxidative stress. All these combined effects result in a significantly efficient tumor suppression outcome. This study enriches sonosensitizer research and proves that sonosensitizers can be rationally optimized by charge separation engineering strategy.

A Robust Oxygen-Carrying Hemoglobin-Based Natural Sonosensitizer for Sonodynamic Cancer Therapy

The development of novel sonosensitizers with outstanding reactive oxygen (ROS) generation capacity and great biocompatibility poses a significant challenge for the clinical practice of sonodynamic therapy (SDT). In this work, hemoglobin (Hb) with natural metalloporphyrin was first shown to possess great potential as a sonosensitizer. Compared with traditional organic sonosensitizers, Hb had satisfactory sono-sensitizing efficiency because four the porphyrin molecules were separated by four polypeptide chains. This effectively avoided the problem of low ROS quantum yield caused by the stacking of hydrophobic porphyrins. Meanwhile, Hb is an efficient and safe oxygen carrier that may release O₂ at hypoxic tumors site, which improved tumor oxygenation and subsequently enhanced SDT efficacy. Therefore, Hb was integrated with zeolitic imidazolate framework 8 (ZIF-8) to form a nanoplatform that demonstrated a potent suppression effect on deep-seated tumors under ultrasound irradiation.

Tumor-killing nanoreactors fueled by tumor debris can enhance radiofrequency ablation therapy and boost antitumor immune responses

Radiofrequency ablation (RFA) is clinically adopted to destruct solid tumors, but is often incapable of completely ablating large tumors and those with multiple metastatic sites. Here we develop a CaCO₃-assisted double emulsion method to encapsulate lipoxidase and hemin with poly(lactic-co-glycolic acid) (PLGA) to enhance RFA. We show the HLCaP nanoreactors (NRs) with pH-dependent catalytic capacity can continuously produce cytotoxic lipid radicals via the lipid peroxidation chain reaction using cancer cell debris as the fuel. Upon being fixed inside the residual tumors post RFA, HLCaP NRs exhibit a suppression effect on residual tumors in mice and rabbits by triggering ferroptosis. Moreover, treatment with HLCaP NRs post RFA can prime antitumor immunity to effectively suppress the growth of both residual and metastatic tumors, also in combination with immune checkpoint blockade. This work highlights that tumor-debris-fueled nanoreactors can benefit RFA by inhibiting tumor recurrence and preventing tumor metastasis.

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

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

Pd-Single-Atom Coordinated Biocatalysts for Chem-/Sono-/Photo-Trimodal Tumor Therapies

The diversity, complexity, and heterogeneity of malignant tumor seriously undermine the efficiency of mono-modal treatment. Recently, multi-modal therapeutics with enhanced antitumor efficiencies have attracted increasing attention. However, designing a nanotherapeutic platform with uniform morphology in nanoscale that integrates with efficient chem-/sono-/photo-trimodal tumor therapies is still a great challenge. Here, new and facile Pd-single-atom coordinated porphyrin-based polymeric networks as biocatalysts, namely, Pd-Pta/Por, for chem-/sono-/photo-trimodal tumor therapies are designed. The atomic morphology and chemical structure analysis prove that the biocatalyst consists of atomic Pd-N coordination networks with a Pd-N2 -Cl2 catalytic center. The characterization of peroxidase-like catalytic activities displays that the Pd-Pta/Por can generate abundant •OH radicals for chemodynamic therapies. The ultrasound irradiation or laser excitation can significantly boost the catalytic production of 1 O2 by the porphyrin-based sono-/photosensitizers to achieve combined sono-/photodynamic therapies. The superior catalytic production of •OH is further verified by density functional theory calculation. Finally, the corresponding in vitro and in vivo experiments have demonstrated their synergistic chem-/sono-/photo-trimodal antitumor efficacies. It is believed that this study provides new promising single-atom-coordinated polymeric networks with highly efficient biocatalytic sites and synergistic trimodal therapeutic effects, which may inspire many new findings in reactive oxygen species-related biological applications across broad therapeutics and biomedical fields.

Inorganic nanomaterials with rapid clearance for biomedical applications

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

Beyond Photo: Xdynamic Therapies in Fighting Cancer

Reactive oxygen species (ROS)-related therapeutic approaches are developed as a promising modality for cancer treatment because the aberrant increase of intracellular ROS level can cause cell death due to nonspecific oxidation damage to key cellular biomolecules. However, the most widely considered strategy, photodynamic therapy (PDT), suffers from critical limitations such as limited tissue-penetration depth, high oxygen dependence, and phototoxicity. Non-photo-induced ROS generation strategies, which are defined as Xdynamic therapies (X = sono, radio, microwave, chemo, thermo, and electro), show good potential to overcome the drawbacks of PDT. Herein, recent advances in the development of Xdynamic therapies, including the design of systems, the working mechanisms, and examples of cancer therapy application, are introduced. Furthermore, the approaches to enhance treatment efficiency of Xdynamic therapy are highlighted. Finally, the perspectives and challenges of these strategies are also discussed.

Engineering nanomedicine for glutathione depletion-augmented cancer therapy

Glutathione (GSH), the main redox buffer, has long been recognized as a pivotal modulator of tumor initiation, progression and metastasis. It is also implicated in the resistance of platinum-based chemotherapy and radiation therapy. Therefore, depleting intracellular GSH was considered a potent solution to combating cancer. However, reducing GSH within cancer cells alone always failed to yield desirable therapeutic effects. In this regard, the convergence of GSH-scavenging agents with therapeutic drugs has thus been pursued in clinical practice. Unfortunately, the therapeutic outcomes are still unsatisfactory due to untargeted drug delivery. Advanced nanomedicine of synergistic GSH depletion and cancer treatment has attracted tremendous interest because they promise to deliver superior therapeutic benefits while alleviating life-threatening side effects. In the past five years, the authors and others have demonstrated that numerous nanomedicines, by simultaneously delivering GSH-depleting agents and therapeutic components, boost not only traditional chemotherapy and radiotherapy but also multifarious emerging treatment modalities, including photodynamic therapy, sonodynamic therapy, chemodynamic therapy, ferroptosis, and immunotherapy, to name a few, and achieved decent treatment outcomes in a large number of rodent tumor models. In this review, we summarize the most recent progress in engineering nanomedicine for GSH depletion-enhanced cancer therapies. Biosynthesis of GSH and various types of GSH-consuming strategies will be briefly introduced. The challenges and perspectives of leveraging nanomedicine for GSH consumption-augmented cancer therapies will be discussed at the end.

Nano-assembly of ruthenium(II) photosensitizers for endogenous glutathione depletion and enhanced two-photon photodynamic therapy

Photodynamic therapy (PDT) is a promising noninvasive cancer treatment. PDT in the clinic faces several hurdles due to the unique tumor environment, a feature of which is high levels of glutathione (GSH). An excess amount of GSH consumes reactive oxygen species (ROS) generated by photosensitizers (PSs), reducing PDT efficiency. Herein, nano-photosensitizers (RuS1 NPs and RuS2 NPs) are reported. These consist of ruthenium complexes joined by disulfide bonds forming GSH sensitive polymer nanoparticles. The NPs achieve enhanced uptake compared to their constituent monomers. Inside cancer cells, high levels of GSH break the S-S bonds releasing PS molecules in the cell. The level of GSH is also then reduced leading to excellent PDT activity. Furthermore, RuS2 NPs functionalized with tumor targeting hyaluronic acid (HA@RuS2 NPs) assessed in vivo were highly effective with minimal side effects. To the best of our knowledge, RuS NPs are the first metal complex-based nano-assembled photosensitizers which exhibit enhanced specificity and consume endogenous GSH simultaneously, thus achieving excellent two-photon PDT efficiency in vitro and in vivo.

Injectable Hydrogel for Cu2+ Controlled Release and Potent Tumor Therapy

Disulfiram (DSF) is an important drug for the treatment and management of alcohol dependency. This drug has been approved by US-FDA, and its activity against the tumor is dependent on copper ion (Cu²⁺). However, the copper toxicity (caused via external copper) and its intrinsic anfractuous distribution in the human body have adversely suppressed the mechanism of DSF in in vivo. In this study, we aimed to design an injectable hydrogel, as CRC (Cu²⁺ release controller) for the effective treatment of tumors. The hydrogels of agarose have been used for wrapping of CuCl₂, and hierarchical microparticles (HMP) for the generation of CRC system. When the laser irradiations (808 nm) have been provided to the system, light energy is transferred into heat energy, which results in the hydrogel hydrolysis (reversible) due to the overheating effect. This is followed by a reaction with DSF (pre-injected) to suppress tumor progression. Hence, the CRC system brings innovative ideas for designing of a Cu²⁺ delivery system.

Polymeric Nanosystems for Immunogenic Cell Death-Based Cancer Immunotherapy

Immunotherapy has pointed out a scientific and promising direction for cancer treatment through the rouse of immunosurveillance and the decrease of possible side effects in recent years. In immunotherapy, immunogenic cancer cell death (ICD) plays a critical role in regulating anti-cancer immune system in vivo via the release of damage-associated molecular patterns. ICD can not only induce in situ cancer cells apoptosis, but also arouse the immune response against metastatic tumors, which is of great clinical significance to eradicate tumors. In cancer immunotherapy, polymer nanoparticles have drawn increasing attention as an important component of ICD-based immunotherapy attributing to their controllable size, excellent biocompatibility, promising ability of protecting cargo from surrounding environment, which delivers the antigens or immune inducers to antigen-presenting cells, and further triggers sinnvoll T cell response. In this review, the recent advances in the development of polymeric material-based nanosystems for ICD-mediated cancer immunotherapy are summarized. The mechanism of ICD and some current restrictions inhibiting the efficiency of immunotherapy and future prospects are also discussed.

A Multichannel Ca2+ Nanomodulator for Multilevel Mitochondrial Destruction-Mediated Cancer Therapy

Subcellular organelle-targeted nanoformulations for cancer theranostics are receiving increasing attention owing to their benefits of precise drug delivery, maximized therapeutic index, and reduced off-target side effects. Herein, a multichannel calcium ion (Ca2+ ) nanomodulator (CaNMCUR+CDDP ), i.e., a cisplatin (CDDP) and curcumin (CUR) co-incorporating calcium carbonate (CaCO3 ) nanoparticle, is prepared by a facile one-pot strategy in a sealed container with in situ synthesized polydopamine (PDA) as a template to enhance Ca2+ -overload-induced mitochondrial dysfunction in cancer therapy. After systemic administration, the PEGylated CaNMCUR+CDDP (PEG CaNMCUR+CDDP ) selectively accumulates in tumor tissues, enters tumor cells, and induces multilevel destruction of mitochondria by the combined effects of burst Ca2+ release, Ca2+ efflux inhibition by CUR, and chemotherapeutic CDDP, thereby observably boosting mitochondria-targeted tumor inhibition. Fluorescence imaging of CUR combined with photoacoustic imaging of PDA facilitates the visualization of the nanomodulator. The facile and practical design of this multichannel Ca2+ nanomodulator will contribute to the development of multimodal bioimaging-guided organelle-targeted cancer therapy in the future.

Metal-ligand coordination nanomaterials for radiotherapy: emerging synergistic cancer therapy

Radiotherapy (RT) plays a central role in curing malignant tumors. However, the treatment outcome is often impeded by low radiation absorption coefficients and radiation resistance of tumors along with normal tissue radio-toxicity. With the development of nanotechnology, nanomaterials in combination with RT offer the possibility to improve the therapeutic efficacy yet reduce side-effects. Metal-ligand coordination nanomaterials, including nanoscale metal-organic frameworks (NMOFs) and nanoscale coordination polymers (NCPs), formed by coordination interactions between inorganic metal ions/clusters with organic bridging ligands, have shown great potential in the field of radiation oncology in recent years in view of their unique advantages including the porous structure, high surface area, periodic frameworks, and diverse selections of both metal ions/clusters and organic ligands. In this review, we summarize the recent advances in NMOF/NCP-mediated synergistic RT in combination with hypoxia relief, chemotherapy, photodynamic therapy, photothermal therapy, chemodynamic therapy or immunotherapy, which emerged in the last 3 years, and describe cooperative enhancement interactions among these synergistic combinations. Moreover, the potential challenges and future prospects of this rapidly growing direction were also addressed.

UV-trained and metal-enhanced fluorescence of biliverdin and biliverdin nanoparticles

Increasing the fluorescence quantum yield of fluorophores is of great interest for in vitro and in vivo biomedical imaging applications. At the same time, photobleaching and photodegradation resulting from continuous exposure to light are major considerations in the translation of fluorophores from research applications to industrial or healthcare applications. A number of tetrapyrrolic compounds, such as heme and its derivatives, are known to provide fluorescence contrast. In this work, we found that biliverdin (BV), a naturally-occurring tetrapyrrolic fluorophore, exhibits an increase in fluorescence quantum yield, without exhibiting photobleaching or degradation, in response to continuous ultraviolet (UV) irradiation. We attribute this increased fluorescence quantum yield to photoisomerization and conformational changes in BV in response to UV irradiation. This enhanced fluorescence can be further altered by chelating BV with metals. UV irradiation of BV led to an approximately 10-fold increase in its 365 nm fluorescence quantum yield, and the most favorable combination of UV irradiation and metal chelation led to an approximately 18.5-fold increase in its 365 nm fluorescence quantum yield. We also evaluated these stimuli-responsive behaviors in biliverdin nanoparticles (BVNPs) at the bulk-state and single-particle level. We determined that UV irradiation led to an approximately 2.4-fold increase in BVNP 365 nm quantum yield, and the combination of UV irradiation and metal chelation led to up to a 6.75-fold increase in BVNP 365 nm quantum yield. Altogether, these findings suggest that UV irradiation and metal chelation can be utilized alone or in combination to tailor the fluorescence behavior of imaging probes such as BV and BVNPs at selected wavelengths.

Ultrasound-Augmented Mitochondrial Calcium Ion Overload by Calcium Nanomodulator to Induce Immunogenic Cell Death

Immunogenic cell death (ICD), a manner of tumor cell death that can trigger antitumor immune responses, has received extensive attention as a potential synergistic modality for cancer immunotherapy. Although many calcium ion (Ca²⁺) nanomodulators have been developed for cancer therapy through mitochondrial Ca²⁺ overload, their ICD-inducing properties have not been explored. Herein, an acid-sensitive PEG-decorated calcium carbonate (CaCO₃) nanoparticle incorporating curcumin (CUR; a Ca²⁺ enhancer) (^PEGCaCUR) was prepared using a simple one-pot strategy. ^PEGCaCUR served as not only a Ca²⁺ nanomodulator inducing efficient mitochondrial Ca²⁺ overload but also an ICD inducer during improved synergistic cancer therapy. Combination of ^PEGCaCUR with ultrasound (US), ^PEGCaCUR+US, led to an enhanced ICD effect attributable to the enhanced mitochondrial Ca²⁺ overload, along with subsequent upregulation of reactive oxygen species levels. ^PEGCaCUR also facilitates photoacoustic/fluorescence dual-mode imaging, as well as effectively suppressing tumor growth and metastasis, indicating promising theranostic properties.

One Responsive Stone, Three Birds: Mn(III)-Hemoporfin Frameworks with Glutathione-Enhanced Degradation, MRI, and Sonodynamic Therapy

Ultrasound-driven sonodynamic therapy (SDT) catches numerous attentions for destroying deep-seated tumors, but its applications suffer from unsatisfactory therapeutic effects and metabolism. Furthermore, SDT is usually weakened by the complex tumor microenvironment, such as the overexpression of glutathione (GSH). To address these issues, Mn(III)-hemoporfin frameworks (Mn(III)-HFs) are reported as nanosonosensitizers by using biocompatible hematoporphyrin monomethyl-ether (HMME) to coordinate with Mn(III) ions. Mn(III)-HFs/PEG can react with GSH to produce Mn(II) ions and oxidized glutathione (GSSG), resulting in three fascinating features: 1) the redox reaction facilitates the decomposition of Mn(III)-HFs/PEG and then collapse of nanostructures, improving the biodegradability; 2) Mn(II) ions with five unpaired 3d-electrons exhibit better magnetic resonance imaging (MRI) ability compared to Mn(III) ions with four electrons; 3) both the depletion of endogenous GSH and the dissociated HMME boost ¹ O₂ generation ability under US irradiation. As a result, when Mn(III)-HFs/PEG dispersion is intravenously administered into mice, it exhibits high-contrast T₁ /T₂ dual-modal MRI and significant suppression for the growth rate of the deep-seated tumor. Furthermore, Mn(III)-HFs/PEG can be efficiently metabolized from the mice. Therefore, Mn(III)-HFs/PEG exhibit GSH-enhanced degradation, MRI, and SDT effects, which provide some insights on the developments of other responsive nanosonosensitizers.

Bioinspired Spiky Peroxidase-Mimics for Localized Bacterial Capture and Synergistic Catalytic Sterilization

Besides the pandemic caused by the coronavirus outbreak, many other pathogenic microbes also pose a devastating threat to human health, for instance, pathogenic bacteria. Due to the lack of broad-spectrum antibiotics, it is urgent to develop nonantibiotic strategies to fight bacteria. Herein, inspired by the localized "capture and killing" action of bacteriophages, a virus-like peroxidase-mimic (V-POD-M) is synthesized for efficient bacterial capture (mesoporous spiky structures) and synergistic catalytic sterilization (metal-organic-framework-derived catalytic core). Experimental and theoretical calculations show that the active compound, MoO₃ , can serve as a peroxo-complex-intermediate to reduce the free energy for catalyzing H₂ O₂ , which mainly benefits the generation of •OH radicals. The unique virus-like spikes endow the V-POD-M with fast bacterial capture and killing abilities (nearly 100% at 16 µg mL^-1 ). Furthermore, the in vivo experiments show that V-POD-M possesses similar disinfection treatment and wound skin recovery efficiencies to vancomycin. It is suggested that this inexpensive, durable, and highly reactive oxygen species (ROS) catalytic active V-POD-M provides a promising broad-spectrum therapy for nonantibiotic disinfection.

Design and application of inorganic nanoparticles for sonodynamic cancer therapy

This review focus on the recent developments in inorganic nanomaterials for tumor SDT.

Mesenchymal Stem Cells Functionalized Sonodynamic Treatment for Improving Therapeutic Efficacy and Compliance of Orthotopic Oral Cancer

Despite multiple treatment options being available, many critical challenges are still ongoing in the treatment of oral squamous cell carcinoma (OSCC). Particularly, the major hurdle is to avoid facial disfigurement and oral function disability during treatment. Herein, nanoengineered mesenchymal stem cells (MSCs) are developed as a supersonosensitizer, named M/LPV/O₂ , for improving nondestructive sonodynamic therapy (SDT) against OSCC along with good therapeutic compliance. M/LPV/O₂ is composed of an MSCs membrane functionalized liposomal formulation of oxygen-loading perfluorocarbon and sonosensitizer verteporfin (M/LPV/O₂ ), which can not only increase circulation and targeting efficacy but also supply oxygen to overcome tumor-hypoxia-associated resistance in SDT, resulting in enhanced therapeutic outcomes in vitro and in vivo. It is identified that M/LPV/O₂ effectively stimulates the generation of reactive oxygen species even in hypoxic conditions, and consequently tremendously induces cancer cell death. In addition, M/LPV/O₂ displays good tumor accumulation and penetration under ultrasound stimulation, and efficiently induces tumor inhibition and even abrogation, leading to prolonged survival of tumor-bearing mice. Importantly, M/LPV/O₂ -based SDT exhibits minimal systemic adverse effects and successfully maintains oral functions with no facial tissue damage. Therefore, these studies provide a promising therapeutic strategy for OSCC, which has a potential to enhance life quality and compliance after treatment.

Ultrasmall Iron-Doped Titanium Oxide Nanodots for Enhanced Sonodynamic and Chemodynamic Cancer Therapy

Sonodynamic therapy (SDT), which can generate reactive oxygen species (ROS) based on sonosensitizers under ultrasound (US) to kill tumor cells, has emerged as a noninvasive therapeutic modality with high tissue-penetration depth. Herein, ultrasmall iron-doped titanium oxide nanodots (Fe-TiO₂ NDs) are synthesized via a thermal decomposition strategy as a type of sonosensitizers to enhance SDT. Interestingly, the Fe doping in this system appears to be crucial in not only enhancing the US-triggered ROS generation of those NDs but also offering NDs the Fenton-catalytic function to generate ROS from tumor endogenous H₂O₂ for chemodynamic therapy (CDT). After polyethylene glycol (PEG) modification, Fe-TiO₂-PEG NDs demonstrate good physiological stability and biocompatibility. With efficient tumor retention after intravenous injection as revealed by in vivo magnetic resonance (MR) and fluorescent imaging, our Fe-TiO₂ NDs demonstrate much better in vivo therapeutic performance than commercial TiO₂ nanoparticles owing to the combination of CDT and SDT. Moreover, most of those ultrasmall Fe-TiO₂ NDs can be effectively excreted within one month, rendering no obvious long-term toxicity to the treated mice. Our work thus presents a type of multifunctional sonosensitizer for highly efficient cancer treatment via simply doping TiO₂ nanostructures with metal ions.

Recent Advances in Nanomaterial-Assisted Combinational Sonodynamic Cancer Therapy

Ultrasound (US)-triggered sonodynamic therapy (SDT), as a promising noninvasive therapeutic modality, has received ever-increasing attention in recent years. Its specialized chemical agents, named sonosensitizers, are activated by low-intensity US to produce lethal reactive oxygen species (ROS) for oncotherapy. Compared with phototherapeutic strategies, SDT provides many noteworthy opportunities and benefits, such as deeper penetration depth, absence of phototoxicity, and fewer side effects. Nevertheless, previous studies have also demonstrated its intrinsic limitations. Thanks to the facile engineering nature of nanotechnology, numerous novel nanoplatforms are being applied in this emerging field to tackle these intrinsic barriers and achieve continuous innovations. In particular, the combination of SDT with other treatment strategies has demonstrated a superior efficacy in improving anticancer activity relative to that of monotherapies alone. Therefore, it is necessary to summarize the nanomaterial-assisted combinational sonodynamic cancer therapy applications. Herein, the design principles in achieving synergistic therapeutic effects based on nanomaterial engineering methods are highlighted. The ultimate goals are to stimulate the design of better-quality combined sonodynamic treatment schemes and provide innovative ideas for the perspectives of SDT in promoting its future transformation to clinical application.

A pH-Responsive Polymer-CeO2 Hybrid to Catalytically Generate Oxidative Stress for Tumor Therapy

Catalytic generation of reactive oxygen species has been developed as a promising methodology for tumor therapy. Direct O₂^•- production from intratumor oxygen exhibits exceptional tumor therapeutic efficacy. Herein, this therapy strategy is demonstrated by a pH-responsive hybrid of porous CeO₂ nanorods and sodium polystyrene sulfonate that delivers high oxidative activity for O₂^•- generation within acidic tumor microenvironments for chemodynamic therapy and only limited oxidative activity in neutral media to limit damage to healthy organs. The hydrated polymer-nanorod hybrids with large hydrodynamic diameters form nanoreactors that locally trap oxygen and biological substrates inside and improve the charge transfer between the catalysts and substrates in the tumor microenvironment, leading to enhanced catalytic O₂^•- production and consequent oxidation. Together with successful in vitro and in vivo experiments, these data show that the use of hybrids provides a compelling opportunity for the delivery selective chemodynamic tumor therapy.

Metal-Organic Framework Derived Multicomponent Nanoagent as a Reactive Oxygen Species Amplifier for Enhanced Photodynamic Therapy

Intracellular antioxidants such as glutathione (GSH) play a critical role in protecting malignant tumor cells from apoptosis induced by reactive oxygen species (ROS) and in mechanisms of multidrug and radiation resistance. Herein, we rationally design two multicomponent self-assembled photodynamic therapy (PDT) nanoagents, that is, Glup-MFi-c and Glud-MFo-c, which consist of respective GSH-passivation and GSH-depletion linkers in metal-organic frameworks encapsulated with photosensitizers for a deeply comprehensive understanding of GSH-based tumor PDT. Multicomponent coordination, π-π stacking, and electrostatic interactions among metal ions, photosensitizers, and bridging linkers under the protection of a biocompatible polymer generate homogeneous nanoparticles with satisfied size, good colloid stability, and ultrahigh loading capacity. Compared to the GSH-passivated Glup-MFi-c, the GSH-depleted Glud-MFo-c shows pH-responsive release of photosensitizer and [Fe^III(CN)₆] linker in tumor cells to efficiently deplete intracellular GSH, thus amplifying the cell-killing efficiency of ROS and suppressing the tumor growth in vivo. This study demonstrates that Glud-MFo-c acts as a ROS amplifier, providing a useful strategy to deeply understand the role of GSH in combating cancer.

Retooling Cancer Nanotherapeutics' Entry into Tumors to Alleviate Tumoral Hypoxia

Anti-hypoxia cancer nanomedicine (AHCN) holds exciting potential in improving oxygen-dependent therapeutic efficiencies of malignant tumors. However, most studies regarding AHCN focus on optimizing structure and function of nanomaterials with presupposed successful entry into tumor cells. From such a traditional perspective, the main barrier that AHCN needs to overcome is mainly the tumor cell membrane. However, such an oversimplified perspective would neglect that real tumors have many biological, physiological, physical, and chemical defenses preventing the current state-of-the-art AHCNs from even reaching the targeted tumor cells. Fortunately, in recent years, some studies are beginning to intentionally focus on overcoming physiological barriers to alleviate hypoxia. In this Review, the limitations behind the traditional AHCN delivery mindset are addressed and the key barriers that need to be surmounted before delivery to cancer cells and some good ways to improve cell membrane attachment, internalization, and intracellular retention are summarized. It is aimed to contribute to Review literature on this emerging topic through refreshing perspectives based on this work and what is also learnt from others. This Review would therefore assist AHCNs researchers to have a quick overview of the essential information and glean thought-provoking ideas to advance this sub-field in cancer nanomedicine.

Nanoscale covalent organic frameworks as theranostic platforms for oncotherapy: synthesis, functionalization, and applications

Cancer nanomedicine is one of the most promising domains that has emerged in the continuing search for cancer diagnosis and treatment. The rapid development of nanomaterials and nanotechnology provide a vast array of materials for use in cancer nanomedicine. Among the various nanomaterials, covalent organic frameworks (COFs) are becoming an attractive class of upstarts owing to their high crystallinity, structural regularity, inherent porosity, extensive functionality, design flexibility, and good biocompatibility. In this comprehensive review, recent developments and key achievements of COFs are provided, including their structural design, synthesis methods, nanocrystallization, and functionalization strategies. Subsequently, a systematic overview of the potential oncotherapy applications achieved till date in the fast-growing field of COFs is provided with the aim to inspire further contributions and developments to this nascent but promising field. Finally, development opportunities, critical challenges, and some personal perspectives for COF-based cancer therapeutics are presented.

Tumor microenvironment triggered biodegradation of inorganic nanoparticles for enhanced tumor theranostics

Inorganic nanoparticles (NPs)-mediated tumor theranostics have attracted widespread attention due to their unique physicochemical properties, such as optical, electrical, magnetic, and thermal properties. In the past decade, great advancements have been made in inorganic NPs-associated drug delivery, multimodal tumor imaging, and tumor therapy. However, the potential toxicity of inorganic NPs due to their low biodegradability, background signals interference and treatment side effects limit their clinical application. Therefore, developing biodegradable and intelligent NPs is beneficial to avoid excessive metal ions deposition, specific tumor imaging and treatment. In this review, we summarize the recent advances in tumor microenvironment (TME)-triggered biodegradation of inorganic NPs accompanied by imaging signal amplification and the released ions-mediated tumor therapy. First, the feature characteristics of the TME are introduced, including mild acidity, hypoxia, overexpressed reactive oxygen species (ROS), glutathione (GSH), and enzymes et al.; then, the biodegradation of NPs in a TME-induced activation of imaging signals, such as magnetic resonance (MR) imaging and fluorescence imaging is described; furthermore, tumor therapies through "Fenton", "Fenton-like" reactions, and interference of biological effects in cells is presented. Finally, the challenges and outlook for improving the degradation efficiency, imaging, specificity and efficiency of tumor imaging and treatment are discussed.