Recent Advances in Nanomaterial-Assisted Combinational Sonodynamic Cancer Therapy

Harnessing Nanomaterials for Cancer Sonodynamic Immunotherapy

Immunotherapy has made remarkable strides in cancer therapy over the past decade. However, such emerging therapy still suffers from the low response rates and immune-related adverse events. Various strategies have been developed to overcome these serious challenges. Therein, sonodynamic therapy (SDT), as a non-invasive treatment, has received ever-increasing attention especially in the treatment of deep-seated tumors. Significantly, SDT can effectively induce immunogenic cell death to trigger systemic anti-tumor immune response, termed sonodynamic immunotherapy. The rapid development of nanotechnology has revolutionized SDT effects with robust immune response induction. As a result, more and more innovative nanosonosensitizers and synergistic treatment modalities are established with superior efficacy and safe profile. In this review, the recent advances in cancer sonodynamic immunotherapy are summarized with a particular emphasis on how nanotechnology can be explored to harness SDT for amplifying anti-tumor immune response. Moreover, the current challenges in this field and the prospects for its clinical translation are also presented. It is anticipated that this review can provide rational guidance and facilitate the development of nanomaterials-assisted sonodynamic immunotherapy, helping to pave the way for next-generation cancer therapy and eventually achieve a durable response in patients.

Ultrasound-Triggered Cascade Amplification of Nanotherapy

Ultrasound (US)-triggered cascade amplification of nanotherapies has attracted considerable attention as an effective strategy for cancer treatment. With the remarkable advances in materials chemistry and nanotechnology, a large number of well-designed nanosystems have emerged that incorporate presupposed cascade amplification processes and can be activated to trigger therapies such as chemotherapy, immunotherapy, and ferroptosis, under exogenous US stimulation or specific substances generated by US actuation, to maximize antitumor efficacy and minimize detrimental effects. Therefore, summarizing the corresponding nanotherapies and applications based on US-triggered cascade amplification is essential. This review comprehensively summarizes and highlights the recent advances in the design of intelligent modalities, consisting of unique components, distinctive properties, and specific cascade processes. These ingenious strategies confer unparalleled potential to nanotherapies based on ultrasound-triggered cascade amplification and provide superior controllability, thus overcoming the unmet requirements of precision medicine and personalized treatment. Finally, the challenges and prospects of this emerging strategy are discussed and it is expected to encourage more innovative ideas and promote their further development.

A Comprehensive Review of Inorganic Sonosensitizers for Sonodynamic Therapy

Sonodynamic therapy (SDT) is an emerging non-invasive cancer treatment method in the field of nanomedicine, which has the advantages of deep penetration, good therapeutic efficacy, and minimal damage to normal tissues. Sonosensitizers play a crucial role in the process of SDT, as their structure and properties directly determine the treatment outcome. Inorganic sonosensitizers, with their high stability and longer circulation time in the human body, have great potential in SDT. In this review, the possible mechanisms of SDT including the ultrasonic cavitation, reactive oxygen species generation, and activation of immunity are briefly discussed. Then, the latest research progress on inorganic sonosensitizers is systematically summarized. Subsequently, strategies for optimizing treatment efficacy are introduced, including combination therapy and image-guided therapy. The challenges and future prospects of sonodynamic therapy are discussed. It is hoped that this review will provide some guidance for the screening of inorganic sonosensitizers.

ROS in hepatocellular carcinoma: What we know

Hepatocellular carcinoma (HCC), which is a primary liver cancer subtype, has a poor prognosis due to its high degree of malignancy. The lack of early diagnosis makes systemic therapy the only hope for HCC patients with advanced disease; however, resistance to drugs is a major obstacle. In recent years, targeted molecular therapy has gained popularity as a potential treatment for HCC. An increase in reactive oxygen species (ROS), which are cancer markers and a potential target for HCC therapy, can both promote and inhibit the disease. At present, many studies have examined targeted regulation of ROS in the treatment of HCC. Here, we reviewed the latest drugs that are still in the experimental stage, including nanocarrier drugs, exosome drugs, antibody drugs, aptamer drugs and polysaccharide drugs, to provide new hope for the clinical treatment of HCC patients.

Antitumor Effects of a Distinct Sonodynamic Nanosystem through Enhanced Induction of Immunogenic Cell Death and Ferroptosis with Modulation of Tumor Microenvironment

Sonodynamic therapy (SDT) holds great promise to be applied for cancer therapy in clinical settings. However, its poor therapeutic efficacy has limited its applications owing to the apoptosis-resistant mechanism of cancer cells. Moreover, the hypoxic and immunosuppressive tumor microenvironment (TME) also weakens the efficacy of immunotherapy in solid tumors. Therefore, reversing TME remains a formidable challenge. To circumvent these critical issues, we developed an ultrasound-augmented strategy to regulate the TME by utilizing an HMME-based liposomal nanosystem (HB liposomes), which can synergistically promote the induction of ferroptosis/apoptosis/immunogenic cell death (ICD) and initiate the reprograming of TME. The RNA sequencing analysis demonstrated that apoptosis, hypoxia factors, and redox-related pathways were modulated during the treatment with HB liposomes under ultrasound irradiation. The in vivo photoacoustic imaging experiment showed that HB liposomes enhanced oxygen production in the TME, alleviated TME hypoxia, and helped to overcome the hypoxia of the solid tumors, consequently improving the SDT efficiency. More importantly, HB liposomes extensively induced ICD, resulting in enhanced T-cell recruitment and infiltration, which normalizes the immunosuppressive TME and facilitates antitumor immune responses. Meanwhile, the HB liposomal SDT system combined with PD1 immune checkpoint inhibitor achieves superior synergistic cancer inhibition. Both in vitro and in vivo results indicate that the HB liposomes act as a sonodynamic immune adjuvant that is able to induce ferroptosis/apoptosis/ICD via generated lipid-reactive oxide species during the SDT and reprogram TME due to ICD induction. This sonodynamic nanosystem integrating oxygen supply, reactive oxygen species generation, and induction of ferroptosis/apoptosis/ICD is an excellent strategy for effective TME modulation and efficient tumor therapy.

Modulation of Intratumoral Fusobacterium nucleatum to Enhance Sonodynamic Therapy for Colorectal Cancer with Reduced Phototoxic Skin Injury

Intratumoral pathogens can contribute to cancer progression and affect therapeutic response. Fusobacterium nucleatum, a core pathogen of colorectal cancer (CRC), is an important cause of low therapeutic efficacy and metastasis. Thus, the modulation of intratumoral pathogens may provide a target for cancer therapy and metastasis inhibition. Herein, we propose an intratumoral F. nucleatum-modulating strategy for enhancing the therapeutic efficacy of CRC and inhibiting lung metastasis by designing an antibacterial nanoplatform (Au@BSA-CuPpIX), which produced reactive oxygen species (ROS) under ultrasound and exhibited strong antibacterial activity. Importantly, Au@BSA-CuPpIX reduced the levels of apoptosis-inhibiting proteins by inhibiting intratumoral F. nucleatum, thereby enhancing ROS-induced apoptosis. In vivo results demonstrated that Au@BSA-CuPpIX effectively eliminated F. nucleatum to enhance the therapeutic efficacy of sonodynamic therapy (SDT) for orthotopic CRC and inhibit lung metastasis. Notably, entrapped gold nanoparticles reduced the phototoxicity of metalloporphyrin accumulated in the skin during tumor treatment, preventing severe inflammation and damage to the skin. Therefore, this study proposes a strategy for the elimination of F. nucleatum in CRC to enhance the therapeutic effect of SDT, thus providing a promising paradigm for improving cancer treatment with fewer toxic side effects and promoting the clinical translational potential of SDT.

Bioengineered nanogenerator with sustainable reactive oxygen species storm for self-reinforcing sono-chemodynamic oncotherapy

Oxidative stress-based antitumor modalities derived from reactive oxygen species (ROS) storms have attracted increasing attention. Nevertheless, low delivery efficiency, poor selectivity, hypoxia and overexpressed glutathione (GSH) have severely restricted the sustainable generation of the ROS storm in tumor cells. Herein, we design a bioengineered nanogenerator by coordination-driven co-assembly of sonosensitizer indocyanine green (ICG), Fenton-like agent copper ion (Cu^Ⅱ) and mitochondrial respiratory inhibitor metformin (MET), which is then camouflaged by a cancer cytomembrane to induce a sustainable intracellular ROS storm for on-demand self-reinforcing sono-chemodynamic oncotherapy. Such a nanogenerator with a core-shell structure, suitable diameter and outstanding stability can efficiently accumulate in tumor regions and then internalize into tumor cells through the camouflaging and homologous targeting strategy of the cancer cytomembrane. The nanogenerator shows an exceptional instability under the triple stimulations of acidic lysosomes, overexpressed GSH and ultrasound (US) radiation, thereby resulting in the rapid disassembly and burst drug release. Interestingly, the released MET significantly enhances the sonodynamic therapy (SDT) efficacy of the released ICG by inhibiting mitochondrial respiration and meanwhile the released Cu^Ⅱ obviously reduces ROS elimination by downregulating overexpressed GSH for self-amplifying and self-protecting the intracellular ROS storm. Moreover, such a nanogenerator almost completely achieves the tumor ablation in vivo in a single therapy cycle. Taken together, our bioengineered nanogenerator with a sustainable ROS storm can provide a promising strategy for ROS storm-based oncotherapy.

ROS-generating alginate-coated gold nanorods as biocompatible nanosonosensitisers for effective sonodynamic therapy of cancer

Sonodynamic therapy (SDT) emerges as a promising non-invasive alternative for eradicating malignant tumours. However, its therapeutic efficacy remains limited due to the lack of sonosensitisers with high potency and biosafety. Previously, gold nanorods (AuNRs) have been extensively studied for their applications in photodynamic or photothermal cancer therapy, but their sonosensitising properties are largely unexplored. Here, we reported the applicability of alginate-coated AuNRs (AuNRs^ALG) with improved biocompatibility profiles as promising nanosonosensitisers for SDT for the first time. AuNRs^ALG were found stable under ultrasound irradiation (1.0 W/cm², 5 min) and maintained structural integrity for 3 cycles of irradiation. The exposure of the AuNRs^ALG to ultrasound irradiation (1.0 W/cm², 5 min) was shown to enhance the cavitation effect significantly and generate a 3 to 8-fold higher amount of singlet oxygen (¹O₂) than other reported commercial titanium dioxide nanosonosensitisers. AuNRs^ALG exerted dose-dependent sonotoxicity on human MDA-MB-231 breast cancer cells in vitro, with ∼ 81% cancer cell killing efficacy at a sub-nanomolar level (IC₅₀ was 0.68 nM) predominantly through apoptosis. The protein expression analysis showed significant DNA damage and downregulation of anti-apoptotic Bcl-2, suggesting AuNRs^ALG induced cell death through the mitochondrial pathway. The addition of mannitol, a reactive oxygen species (ROS) scavenger, inhibited cancer-killing effect of AuNRs^ALG-mediated SDT, further verifying that the sonotoxicity of AuNRs^ALG is driven by the production of ROS. Overall, these results highlight the potential application of AuNRs^ALG as an effective nanosonosensitising agent in clinical settings.

Tumor-targeted AIE polymeric micelles mediated immunogenic sonodynamic therapy inhibits cancer growth and metastasis

Aggregation-induced emission luminogens (AIEgens) exhibit potent sonosensitivity in nanocarriers compared with conventional organic sonosensitizers owing to the strong fluorescence emission in the aggregated state. However, the premature drug leakage and ineffective tumor targeting of current AIE nanosonosensitizers critically restrict their clinical applications. Here, an AIEgen-based sonosensitizer (AIE/Biotin-M) with excellent sonosensitivity was developed by assembling salicylaldazine-based amphiphilic polymers (AIE-1) and 4T1 tumor-targeting amphiphilic polymers (DSPE-PEG-Biotin) for the effective delivery of salicylaldazine to 4T1 tumor tissues, aiming to mediate immunogenic SDT. In vitro, AIE/Biotin-M were highly stable and generated plentiful singlet oxygen (¹O₂) under ultrasound (US) irradiation. After AIE/Biotin-M targeted accumulation in the tumor, upon US irradiation, the generation of ¹O₂ not only led to cancer cell death, but also elicited a systemically immune response by causing the immunogenic cell death (ICD) of cancer cells. In addition to mediating SDT, AIE/Biotin-M could chelate and reduce Fe³⁺, Cu²⁺ and Zn²⁺ by salicylaldazine for inhibiting neovascularization in tumor tissues. Ultimately, AIE/Biotin-M systemically inhibited tumor growth and metastasis upon US irradiation. This study presents a facile approach to the development of AIE nanosonosensitizers for cancer SDT.

2D Nano-Sonosensitizers Facilitate Energy Transfer to Enhance Sonodynamic Therapy

Although sonodynamic therapy (SDT) has shown promise for cancer treatment, the lack of efficient sonosensitizers (SSs) has limited the clinical application of SDT. Here, a new strategy is reported for designing efficient nano-sonosensitizers based on 2D nanoscale metal-organic layers (MOLs). Composed of Hf-oxo secondary building units (SBUs) and iridium-based linkers, the MOL is anchored with 5,10,15,20-tetra(p-benzoato)porphyrin (TBP) sensitizers on the SBUs to afford TBP@MOL. TBP@MOL shows 14.1- and 7.4-fold higher singlet oxygen (1 O2 ) generation than free TBP ligands and Hf-TBP, a 3D nanoscale metal-organic framework, respectively. The 1 O2 generation of TBP@MOL is enhanced by isolating TBP SSs on the SBUs of the MOL, which prevents aggregation-induced quenching of the excited sensitizers, and by triplet-triplet Dexter energy transfer between excited iridium-based linkers and TBP SSs, which more efficiently harnesses broad-spectrum sonoluminescence. Anchoring TBP on the MOL surface also enhances the energy transfer between the excited sensitizer and ground-state triplet oxygen to increase 1 O2 generation efficacy. In mouse models of colorectal and breast cancer, TBP@MOL demonstrates significantly higher SDT efficacy than Hf-TBP and TBP. This work uncovers a new strategy to design effective nano-sonosensitizers by facilitating energy transfer to efficiently capture broad-spectrum sonoluminescence and enhance 1 O2 generation.

Piezocatalytic 2D WS2 Nanosheets for Ultrasound-Triggered and Mitochondria-Targeted Piezodynamic Cancer Therapy Synergized with Energy Metabolism-Targeted Chemotherapy

Piezoelectric nanomaterials that can generate reactive oxygen species (ROS) by piezoelectric polarization under an external mechanical force have emerged as an effective platform for cancer therapy. In this study, piezoelectric 2D WS₂ nanosheets are functionalized with mitochondria-targeting triphenylphosphonium (TPP) for ultrasound (US)-triggered, mitochondria-targeted piezodynamic cancer therapy. In addition, a glycolysis inhibitor (FX11) that can inhibit cellular energy metabolism is loaded into TPP- and poly(ethylene glycol) (PEG)-conjugated WS₂ nanosheet (TPEG-WS₂ ) to potentiate its therapeutic efficacy. Upon US irradiation, the sono-excited electrons and holes generated in the WS₂ are efficiently separated by piezoelectric polarization, which subsequently promotes the production of ROS. FX11-loaded TPEG-WS₂ (FX11@TPEG-WS₂ ) selectively accumulates in the mitochondria of human breast cancer cells. In addition, FX11@TPEG-WS₂ effectively inhibits the production of adenosine triphosphate . Thus, FX11@TPEG-WS₂ exhibits outstanding anticancer effects under US irradiation. An in vivo study using tumor-xenograft mice demonstrates that FX11@TPEG-WS₂ effectively accumulated in the tumors. Its tumor accumulation is visualized using in vivo computed tomography . Notably, FX11@TPEG-WS₂ with US irradiation remarkably suppresses the tumor growth of mice without systemic toxicity. This study demonstrates that the combination of piezodynamic therapy and energy metabolism-targeted chemotherapy using mitochondria-targeting 2D WS₂ is a novel strategy for the selective and effective treatment of tumors.

Multi-Targeted Peptide-Modified Gold Nanoclusters for Treating Solid Tumors in the Liver

Apoptosis and autophagy determine the fate of cancer cells. However, simply promoting apoptosis of tumor cells is limited in the treatment of unresectable solid liver tumors. Generally, autophagy is considered the anti-apoptotic "guardian". But the pro-apoptotic effects of autophagy can be activated by excessive endoplasmic reticulum (ER) stress. Here, amphiphilic peptide-modified glutathione (GSH)-gold nanocluster aggregates (AP₁ P₂ -PEG NCs) were designed with the enrichment of solid liver tumors and the prolonged stress in the ER, which can achieve the mutual promotion of autophagy and apoptosis in liver tumor cells. In this study, orthotopic and subcutaneous liver tumor models show the anti-tumor effectiveness of AP₁ P₂ -PEG NCs, with a better antitumor effect than sorafenib, biosafety (Lethal Dose, 50% (LD₅₀ ) of 827.3 mg kg^-1 ), wide therapeutic window (non-toxic in 20 times of therapeutic concentration) and high stability (blood half-life of 4 h). These findings identify an effective strategy to develop peptide-modified gold nanocluster aggregates with low toxicity, high potency, and selectivity for solid liver tumors treatment.

Semiconducting Titanate Supported Ruthenium Clusterzymes for Ultrasound-Amplified Biocatalytic Tumor Nanotherapies

The external-stimulation-induced reactive-oxygen-species (ROS) generation has attracted increasing attention in therapeutics for malignant tumors. However, engineering a nanoplatform that integrates with efficient biocatalytic ROS generation, ultrasound-amplified ROS production, and simultaneous relief of tumor hypoxia is still a great challenge. Here, we create new semiconducting titanate-supported Ru clusterzymes (RuNC/BTO) for ultrasound-amplified biocatalytic tumor nanotherapies. The morphology and chemical/electronic structure analysis prove that the biocatalyst consists of Ru nanoclusters that are tightly stabilized by Ru-O coordination on BaTiO₃ . The peroxidase (POD)- and halogenperoxidase-like biocatalysis reveals that the RuNC/BTO can produce abundant •O₂ ^- radicals. Notably, the RuNC/BTO exhibits the highest turnover number (63.29 × 10^-3 s^-1 ) among the state-of-the-art POD-mimics. Moreover, the catalase-like activity of the RuNC/BTO facilitates the decomposition of H₂ O₂ to produce O₂ for relieving the hypoxia of the tumor and amplifying the ROS level via ultrasound irradiation. Finally, the systematic cellular and animal experiments have validated that the multi-modal strategy presents superior tumor cell-killing effects and suppression abilities. We believe that this work will offer an effective clusterzyme that can adapt to the tumor microenvironment-specific catalytic therapy and also provide a new pathway for engineering high-performance ROS production materials across broad therapeutics and biomedical fields.

Ultrasound-Activatable g-C3 N4 -Anchored Titania Heterojunction as an Intracellular Redox Homeostasis Perturbator for Augmented Oncotherapy

Energy band structure of inorganic nano-sonosensitizers is usually optimized by surface decoration with noble metals or metal oxide semiconductors, aiming to enhance interfacial charge transfer, augment spin-flip and promote radical generation. To avoid potential biohazards of metallic elements, herein, metal-free graphitic carbon nitride quantum dots (g-C₃ N₄ QDs) are anchored onto hollow mesoporous TiO₂ nanostructure to formulate TiO₂ @g-C₃ N₄ heterojunction. The direct Z-scheme charge transfer significantly improves the separation/recombination dynamics of electron/hole (e^- /h⁺ ) pairs upon ultrasound (US) stimulation, which promotes the yield of singlet oxygen (¹ O₂ ) and hydroxyl radicals (·OH). The conjugated g-C₃ N₄ QDs with peroxidase-mimic activity further react with the elevated endogenous H₂ O₂ and aggravate oxidative stress. After loading prodrug romidepsin (RMD) in TiO₂ @g-C₃ N₄ , stimulus-responsive drug delivery can be realized by US irradiation. The disulfide bridge of the released RMD tends to be reduced by glutathione (GSH) into a monocyclic dithiol, which arrests cell cycle in G2/M phase and evokes apoptosis through enhanced histone acetylation. Importantly, reactive oxygen species accumulation accompanied by GSH depletion is devoted to deleterious redox dyshomeostasis, leading to augmented systemic oncotherapy by eliciting antitumor immunity. Collectively, this paradigm provides useful insights in optimizing the performance of TiO₂ -based nano-sonosensitizers for tackling critical diseases.

Near-infrared-II-activatable sulfur-deficient plasmonic Bi2S3-x-Au heterostructures for photoacoustic imaging-guided ultrasound enhanced high performance phototherapy

Bismuth sulfide is widely used as an n-type semiconductor material in photocatalytic reactions. However, bismuth sulfide has poor absorption in the near-infrared region and low charge separation efficiency, limiting its application in phototherapy and sonodynamic therapy (SDT). In this study, we successfully synthesized an "all-in-one" phototheranostic nanoplatform, namely Bi₂S_3-x-Au@HA, based on a single second near-infrared (NIR-II) light-responsive Schottky-type Bi₂S_3-x-Au heterostructure for photoacoustic (PA) imaging-guided SDT-enhanced photodynamic therapy (PDT)/photothermal therapy (PTT). Bi₂S_3-x-Au@HA exhibits excellent NIR-II plasmonic and photothermal properties, rendering it with NIR-II PA imaging capabilities for accurate diagnosis. Additionally, the high-density sulfur vacancies constructed on the Bi₂S₃ surface cause it to possess a reduced band gap (1.21 eV) that can act as an electron trap. Using the density functional theory, we confirmed that the light and ultrasound-induced electrons are more likely to aggregate on the Au nanoparticle surface through interfacial self-assembly, which promotes electron-hole separation and enhances photocatalytic activity with increased reactive oxygen species (ROS) generation. With a further modification of hyaluronic acid (HA), Bi₂S_3-x-Au@HA can selectively target cancer cells through HA and CD44 protein interactions. Both in vitro and in vivo experiments demonstrated that Bi₂S_3-x-Au@HA effectively suppressed tumor growth through SDT-enhanced PTT/PDT under a single NIR-II laser and ultrasound irradiation with negligible toxicity. Our findings provide a framework for fabricating Schottky-type heterostructures as single NIR-II light-responsive nanotheranostic agents for PA imaging-guided cancer phototherapy.

Sonopiezoelectric Nanomedicine and Materdicine

Endogenous electric field is ubiquitous in a multitude of important living activities such as bone repair, cell signal transduction, and nerve regeneration, signifying that regulating the electric field in organisms is highly beneficial to maintain organism health. As an emerging and promising research direction, piezoelectric nanomedicine and materdicine precisely activated by ultrasound with synergetic advantages of deep tissue penetration, remote spatiotemporal selectivity, and mechanical-electrical energy interconversion, have been progressively utilized for disease treatment and tissue repair by participating in the modulation of endogenous electric field. This specific nanomedicine utilizing piezoelectric effect activated by ultrasound is typically regarded as "sonopiezoelectric nanomedicine". This comprehensive review summarizes and discusses the substantially employed sonopiezoelectric nanomaterials and nanotherapies to provide an insight into the internal mechanism of the corresponding biological behavior/effect of sonopiezoelectric biomaterials in versatile disease treatments. This review primarily focuses on the sonopiezoelectric biomaterials for biosensing, drug delivery, tumor therapy, tissue regeneration, antimicrobia, and further illuminates the underlying sonopiezoelectric mechanism. In addition, the challenges and developments/prospects of sonopiezoelectric nanomedicine are analyzed for promoting the further clinical translation. It is earnestly expected that this kind of nanomedicine/biomaterials-enabled sonopiezoelectric technology will provoke the comprehensive investigation and promote the clinical development of the next-generation multifunctional materdicine.

An Intelligent Cell-Derived Nanorobot Bridges Synergistic Crosstalk Between Sonodynamic Therapy and Cuproptosis to Promote Cancer Treatment

Recent progress in cuproptosis sheds light on the development of treatment approaches for advancing sonodynamic therapy (SDT) due to its unique cell death mechanism. Herein, we elaborately developed an intelligent cell-derived nanorobot (SonoCu), composed of macrophage-membrane-camouflaged nanocarrier encapsulating copper-doped zeolitic imidazolate framework-8 (ZIF-8), perfluorocarbon, and sonosensitizer Ce6, for synergistically triggering cuproptosis-augmented SDT. SonoCu not only improved tumor accumulation and cancer-cell uptake through cell-membrane camouflaging but responded to ultrasound stimuli to enhance intratumor blood flow and oxygen supply, which consequently overcame treatment barriers and activated sonodynamic cuproptosis. Importantly, the SDT effectiveness could be further amplified by cuproptosis through multiple mechanisms, including reactive oxygen species accumulation, proteotoxic stress, and metabolic regulation, which synergistically sensitized cancer cell death. Particularly, SonoCu exhibited ultrasound-responsive cytotoxicity against cancer cells but not healthy cells, endowing it with good biosafety. Therefore, we present the first anticancer combination of SDT and cuproptosis, which may inspire studies pursuing a rational multimodal treatment strategy.

Multifunctional nanodrug performs sonodynamic therapy and inhibits TGF-β to boost immune response against colorectal cancer and liver metastasis

Liver metastasis is the leading cause of death in colorectal cancer. Immunotherapy using immune checkpoint blockade (ICB) is ineffective due to its immunological cold tumor nature. Herein, we prepared a nanodrug (NCG) encapsulating the transforming growth factor-β receptor inhibitor galunisertib (Gal) and the sonosensitizer chlorin e6 (Ce6), which was aimed to turn this type of cold tumor into a hot one to promote the ICB-based immunotherapy against it. After delivery to the tumor, NCG under ultrasonic irradiation generated reactive oxygen species causing tumor immunogenic cell death and releasing immunostimulatory signals such as calreticulin and HMGB1, which increased tumor immunogenicity and activated the innate T lymphocyte immune response. Moreover, NCG responded to the acidic microenvironment and released Gal, inhibiting phosphorylation and inducing immunosuppressive Smad2/3 signaling. Consequently, the differentiation of MDSCs was inhibited, M1-like polarization of tumor-associated macrophages was induced, and the immunosuppressive barrier of tumor-associated fibroblasts was destroyed to increase the infiltration of effector T cells, which reversed the immunosuppression of the tumor microenvironment and improved the therapeutic efficacy of anti-PD-L1 antibodies. Notably, in the liver metastasis mouse model, combination therapy using NCG (+) and aPD-L1 inhibited the growth of colon cancer liver metastasis, manifesting potential in treating this popular yet intractable malignancy. STATEMENT OF SIGNIFICANCE: Only a limited number of patients with colorectal cancer and liver metastasis can benefit from immune checkpoint blockade therapy, as most of them are microsatellite stable, immunologically cold tumors. Interestingly, there is compelling evidence that sonodynamic therapy (SDT) can convert immunosuppressed cold tumors into hot ones, trigger tumor immunogenic cell death non-invasively, and boost cytotoxic T cells infiltration. However, its therapeutic efficacy is constrained by the abundance of transforming growth factor-β (TGF-β) cytokines in the tumor microenvironment. Here, we reported a TGF-β-targeted inhibitory nanodrug that improved SDT in colon cancer and liver metastasis, reversed the immunosuppressive tumor microenvironment and boosted the immune response to anti-PD-L1 therapy in this cancer. It demonstrated the potential to cure this prevalent but incurable malignancy.

Recent Progress in NIR-II Fluorescence Imaging-guided Drug Delivery for Cancer Theranostics

Fluorescence imaging in the second near-infrared window (NIR-II) has become a prevalent choice owing to its appealing advantages like deep penetration depth, low autofluorescence, decent spatiotemporal resolution, and a high signal-to-background ratio. This would expedite the innovation of NIR-II imaging-guided drug delivery (IGDD) paradigms for the improvement of the prognosis of patients with tumors. This work systematically reviews the recent progress of such NIR-II IGDD-mediated cancer therapeutics and collectively brings its essence to the readers. Special care has been taken to assess their performances based on their design approach, such as enhancing their drug loading and triggering release, designing intrinsic and extrinsic fluorophores, and/ or overcoming biological barriers. Besides, the state-of-the-art NIR-II IGDD platforms for different therapies like chemo-, photodynamic, photothermal, chemodynamic, immuno-, ion channel, gas-therapies, and multiple functions such as stimulus-responsive imaging and therapy, and monitoring of drug release and therapeutic response, have been updated. In addition, for boosting theranostic outcomes and clinical translation, the innovation directions of NIR-II IGDD platforms are summarized, including renal-clearable, biodegradable, sub-cellular targeting, and/or afterglow, chemiluminescence, X-ray excitable NIR-IGDD, and even cell therapy. This review will propel new directions for safe and efficient NIR-II fluorescence-mediated anticancer drug delivery.

Recent advances in stimuli-responsive nano-heterojunctions for tumor therapy

Stimuli-responsive catalytic therapy based on nano-catalysts has attracted much attention in the field of biomedicine for tumor therapy, due to its excellent and unique properties. However, the complex tumor microenvironment conditions and the rapid charge recombination in the catalyst limit catalytic therapy's effectiveness and further development. Effective heterojunction nanomaterials are constructed to address these problems to improve catalytic performance. Specifically, on the one hand, the band gap of the material is adjusted through the heterojunction structure to promote the charge separation efficiency under exogenous stimulation and further improve the catalytic capacity. On the other hand, the construction of a heterojunction structure can not only preserve the function of the original catalyst but also achieve significantly enhanced synergistic therapy ability. This review summarized the construction and functions of stimuli-responsive heterojunction nanomaterials under the excitation of X-rays, visible-near infrared light, and ultrasound in recent years, and further introduces their application in cancer therapy. Hopefully, the summary of stimuli-responsive heterojunction nanomaterials' applications will help researchers promote the development of nanomaterials in cancer therapy.

Emerging Advancements in Piezoelectric Nanomaterials for Dynamic Tumor Therapy

Cancer is one of the deadliest diseases, having spurred researchers to explore effective therapeutic strategies for several centuries. Although efficacious, conventional chemotherapy usually introduces various side effects, such as cytotoxicity or multi−drug resistance. In recent decades, nanomaterials, possessing unique physical and chemical properties, have been used for the treatment of a wide range of cancers. Dynamic therapies, which can kill target cells using reactive oxygen species (ROS), are promising for tumor treatment, as they overcome the drawbacks of chemotherapy methods. Piezoelectric nanomaterials, featuring a unique property to convert ultrasound vibration energy into electrical energy, have also attracted increasing attention in biomedical research, as the piezoelectric effect can drive chemical reactions to generate ROS, leading to the newly emerging technique of ultrasound−driven tumor therapy. Piezoelectric materials are expected to bring a better solution for efficient and safe cancer treatment, as well as patient pain relief. In this review article, we highlight the most recent achievements of piezoelectric biomaterials for tumor therapy, including the mechanism of piezoelectric catalysis, conventional piezoelectric materials, modified piezoelectric materials and multifunctional piezoelectric materials for tumor treatment.

Tumor microenvironment remodeling via targeted depletion of M2-like tumor-associated macrophages for cancer immunotherapy

M2-like tumor-associated macrophages (TAMs) typically exhibit numerous tumor-promoting properties. Reducing the abundance of M2-like TAMs would shed light on the relief of immunosuppressive tumor microenvironment (TME), activation of the host immune system, infiltration of CD8⁺ T cells into the TME and restoring the function of the infiltrating T cells, which collectively inhibits tumor growth. Therefore, targeted depletion of M2-like TAMs can be a promising immunotherapy approach. In this study, we rationally constructed an M2-like TAMs-targeted nanoliposome, which encapsulates zoledronic acid (ZA) in the core, loads hematoporphyrin monomethyl ether (HMME, a typical sonosensitizer) in the lipid bilayer, and modifies M2pep peptide (the targeting unit) on the surface (designated as M-H@lip-ZA). Our aim is to validate the effectiveness of M-H@lip-ZA nanoliposomes to remodel TME via targeted depletion of M2-like TAMs for cancer immunotherapy. Through the M2pep peptide, M-H@lip-ZA can be efficiently delivered to M2-like TAMs. In the meantime, reactive oxygen species (ROS) resulting from sonodynamic therapy (SDT), together with inner ZA that shows high affinity and cytotoxicity to TAMs, can effectively deplete M2-like TAMs and remodel TME (normalize tumor vasculatures, strengthen intertumoral perfusion, ease tumor hypoxia, increase immune-promoting cytokines and decrease immunosuppressive cytokines). The tumor growth can be effectively inhibited. This work proposed a new paradigm for cancer immunotherapy via targeted depletion of M2-like TAMs. STATEMENT OF SIGNIFICANCE: • M2-like TAMs-targeted nanoliposome (M-H@lip-ZA) was designed and prepared. • Sonodynamic therapy (SDT), together with zoledronic acid (ZA) that shows high affinity and cytotoxicity to tumor-associated macrophages (TAMs), can effectively deplete M2-like TAMs. Subsequently, immune-promoting tumor microenvironment (TME) can be formed, which includes normalized tumor vasculatures, enhanced intertumoral perfusion, relieved tumor hypoxia, increased immune-promoting cytokines, and decreased immunosuppressive cytokines. • The targeted depletion of M2-like TAMs is a promising cancer immunotherapy approach.

ROS-Triggered Self-Assembled Nanoparticles Based on a Chemo-Sonodynamic Combinational Therapy Strategy for the Noninvasive Elimination of Hypoxic Tumors

The hypopermeability and hypoxia in the tumor milieu are important factors that limit multiple treatments. Herein, the reactive oxygen species (ROS)-triggered self-assembled nanoparticles (RP-NPs) was constructed. The natural small molecule Rhein (Rh) was encapsulated into RP-NPs as a sonosensitizer highly accumulated at the tumor site. Then highly tissue-permeable ultrasound (US) irradiation induced apoptosis of tumor cells through the excitation of Rh and acoustic cavitation, which prompted the rapid production of large amounts of ROS in the hypoxic tumor microenvironment. In addition, the thioketal bond structures in the innovatively designed prodrug LA-GEM were triggered and broken by ROS to achieve rapid targeted release of the gemcitabine (GEM). Sonodynamic therapy (SDT) increased the tissue permeability of solid tumors and actively disrupted redox homeostasis via mitochondrial pathways to kill hypoxic tumor cells, and the triggered response mechanism to GEM synergistically amplified the effect of chemotherapy. The chemo-sonodynamic combinational treatment approach is highly effective and noninvasive, with promising applications for hypoxic tumor elimination, such as in cervical cancer (CCa) patients who want to maintain their reproductive function.

Biomimetic Nanoplatform with H2O2 Homeostasis Disruption and Oxidative Stress Amplification for Enhanced Chemodynamic Therapy

Chemodynamic therapy (CDT) is a powerful cancer treatment strategy by producing excessive amount of reactive oxygen species (ROS) to kill cancer cells. However, the inadequate hydrogen peroxide (H₂O₂) supply and antioxidant defense systems in tumor tissue significantly impair the therapeutic effect of CDT, hindering its further applications. Herein, we present an intelligent nanoplatform with H₂O₂ homeostasis disruption and oxidative stress amplification properties for enhanced CDT. This nanoplatform is obtained by encapsulating glucose oxidase (GOx) in a pH- and glutathione (GSH)-responsive degradable copper doped-zeolitic imidazolate framework (Cu-ZIF8), followed by loading of 3-amino-1,2,4-triazole (3AT) and modification of hyaluronic acid (HA) for tumor targeting delivery. The GOx@Cu-ZIF8-3AT@HA not only reduces energy supply and increases H₂O₂ level by exhausting intratumoral glucose, but also disturbs tumor antioxidant defense systems by inhibiting the activity of catalase and depleting intracellular GSH, resulting in disrupted H₂O₂ homeostasis in tumor. Moreover, the elevated H₂O₂ will transform into highly toxic •OH by Cu⁺ that generated from redox reaction between Cu²⁺ and GSH, amplifying the oxidative stress to enhance the CDT efficacy. Consequently, GOx@Cu-ZIF8-3AT@HA has significantly inhibited the 4T1 xenograft tumor growth without discernible side effects, which provides a promising strategy for cancer management. STATEMENT OF SIGNIFICANCE: The inadequate hydrogen peroxide (H₂O₂) level and antioxidant defense system in tumor tissues significantly impair the therapeutic effect of chemodynamic therapy (CDT). Herein, we developed an intelligent nanoplatform with H₂O₂ homeostasis disruption and oxidative stress amplification properties for enhanced CDT. In this nanoplatform, glucose oxidase (GOx) could exhaust intratumoral glucose to reduce energy supply accompanied with production of H₂O₂, while the suppression of catalase activity by 3-amino-1,2,4-triazole (3AT) and depletion of glutathione by Cu²⁺ would weaken the antioxidant defense system of tumors. Ultimately, the raised H₂O₂ level would convert to highly toxic hydroxyl radical (•OH) by Fenton-like reaction, amplifying the CDT efficacy. This work provides a promising strategy for cancer management.

Photo-/piezo-activated ultrathin molybdenum disulfide nanomedicine for synergistic tumor therapy

Molybdenum disulfide (MoS₂), as a transition metal dichalcogenide, has attracted tremendous attention owing to its remarkable electronic, physical, and chemical properties. In this study, based on the energy-converting nanomedicine, we report multifunctional two-dimensional (2D) MoS₂ nanosheets with inherent plasmonic property and piezocatalytic activity for imaging-guided synergistic tumor therapy. MoS₂ nanosheets display strong plasmon resonances in the near-infrared (NIR) region, especially in the second NIR biological window, possessing a notable light energy to heat effect under 1064 nm laser irradiation, which not only serves as a robust photothermal agent for cancer cell ablation but also acts as a contrast-enhanced agent for thermal imaging and photoacoustic imaging. Meanwhile, MoS₂ nanosheets feature a remarkable piezotronic effect, exhibiting mechanical vibration energy to electricity under the stimulation of ultrasound-mediated microscopic pressure for reactive oxygen species generation to further kill cancer cells. The new function for old materials may open up the in-depth exploration of MoS₂-based functional biomaterials in the future clinical application of imaging-guided photothermal and piezocatalytic synergetic treatment.

Metal-Organic Frameworks (MOF)-Assisted Sonodynamic Therapy in Anticancer Applications

Sonodynamic therapy (SDT) has emerged as a promising therapeutic modality for anticancer treatments and is becoming a cutting-edge interdisciplinary research field. This review starts with the latest developments of SDT and provides a brief comprehensive discussion on ultrasonic cavitation, sonodynamic effect, and sonosensitizers in order to popularize the basic principles and probable mechanisms of SDT. Then the recent progress of MOF-based sonosensitizers is overviewed, and the preparation methods and properties (e.g., morphology, structure, and size) of products are presented in a fundamental perspective. More importantly, many deep observations and understanding toward MOF-assisted SDT strategies were described in anticancer applications, aiming to highlight the advantages and improvements of MOF-augmented SDT and synergistic therapies. Last but not least, the review also pointed out the probable challenges and technological potential of MOF-assisted SDT for the future advance. In all, the discussions and summaries of MOF-based sonosensitizers and SDT strategies will promote the fast development of anticancer nanodrugs and biotechnologies.

Metal Complexes for Cancer Sonodynamic Therapy

Sonodynamic therapy (SDT) for cancer treatment is gaining attention owing to its non-invasive property and ultrasound's (US) deep tissue penetration ability. In SDT, US activates the sonosensitizer at the target deep-seated tumors to generate reactive oxygen species (ROS), which ultimately damage tumors. However, drawbacks such as insufficient ROS production, aggregation of sonosensitizer, off-target side effects, etc., of the current organic/nanomaterial-based sonosensitizers limit the effectiveness of cancer SDT. Very recently, metal complexes with tunable physiochemical properties (such as sonostability, HOMO to LUMO energy gap, ROS generation ability, aqueous solubility, emission, etc.) have been devised as effective sonosensitizers, which could overcome the limitations of organic/nanomaterial-based sonosensitizers. This concept introduces all the reported metal-based sonosensitizers and delineates the prospects of metal complexes in cancer sonodynamic therapy. This new concept of metal-based sonosensitizer can deliver next-generation cancer drugs.

Manganese oxide-modified bismuth oxychloride piezoelectric nanoplatform with multiple enzyme-like activities for cancer sonodynamic therapy

Sonodynamic therapy (SDT) is considered as a new-rising strategy for cancer therapeutics, but the inefficient production of reactive oxygen species (ROS) by current sonosensitizers seriously hinders its further applications. Herein, a piezoelectric nanoplatform is fabricated for enhancing SDT against cancer, in which manganese oxide (MnO_x) with multiple enzyme-like activities is loaded on the surface of piezoelectric bismuth oxychloride nanosheets (BiOCl NSs) to form a heterojunction. When exposed to ultrasound (US) irradiation, piezotronic effect can remarkably promote the separation and transport of US-induced free charges, and further enhance ROS generation in SDT. Meanwhile, the nanoplatform shows multiple enzyme-like activities from MnO_x, which can not only downregulate the intracellular glutathione (GSH) level, but also disintegrate endogenous hydrogen peroxide (H₂O₂) to generate oxygen (O₂) and hydroxyl radicals (•OH). As a result, the anticancer nanoplatform substantially boosts ROS generation and reverses tumor hypoxia. Ultimately, it reveals remarkable biocompatibility and tumor suppression in a murine model of 4 T1 breast cancer under US irradiation. This work provides a feasible pathway for improving SDT using piezoelectric platforms.

Nanodroplet-enhanced sonodynamic therapy potentiates immune checkpoint blockade for systemic suppression of triple-negative breast cancer

Immune checkpoint blockade (ICB) has shown great promise in treating various advanced malignancies including triple-negative breast cancer (TNBC). However, only limited number of patients could benefit from it due to the low immune response rate caused by insufficient matured dendritic cells (DCs) and inadequate tumor infiltration of cytotoxic T lymphocytes (CTLs). Here, we report a combination therapeutic strategy which integrates STING pathway activation, hypoxia relief and sonodynamic therapy (SDT) with anti-PD-L1 therapy to improve the therapeutic outcome. The synthesized nanodroplet consisted of a O₂-filled Perfluorohexane (PFH) core and a lipid membrane carrying sonosensitizer IR-780 and STING agonist Vadimezan (DMXAAs). It released O₂ inside the hypoxic tumor tissue, thereby enhancing SDT which relied on O₂ to generate cytotoxic reactive oxygen species (ROS). The co-delivered STING agonist DMXAAs promoted the maturation and tumor antigen cross-presenting of DCs for priming of CTLs. Moreover, SDT induced immunogenic cell death (ICD) of tumor to release abundant tumor-associated antigens, which increased tumor immunogenicity to promote tumor infiltration of CTLs. Consequently, not only a robust adaptive immune response was elicited but also the immunologically "cold" TNBC was turned "hot" to enable a potent anti-PD-L1 therapy. The nanodroplet demonstrated strong efficacy to systemically suppress TNBC growth and mimic distant tumor in vivo. STATEMENT OF SIGNIFICANCE: Only a limited number of triple-negative breast cancer (TNBC) patients can benefit from immune checkpoint blockade therapy due to its low immune response rate caused by insufficient matured DCs and inadequate tumor infiltration of cytotoxic T lymphocytes (CTLs). Interestingly, compelling evidence has shown that sonodynamic therapy (SDT) not only directly kills cancer cells but also elicits immunogenic cell death (ICD), which promotes tumor infiltration of cytotoxic T lymphocytes to transform an immunosuppressive "cold" tumor into a "hot" one. However, the hypoxic tumor microenvironment severely restricts the therapeutic efficiency of SDT, wherein, oxygen is indispensable in the process of ROS generation. Here, we report an O₂-filled nanodroplet-enhanced sonodynamic therapy that significantly potentiated immune checkpoint blockade for systemic suppression of TNBC.

Titanium-Based Nanoarchitectures for Sonodynamic Therapy-Involved Multimodal Treatments

Sonodynamic therapy (SDT) has considerably revolutionized the healthcare sector as a viable noninvasive therapeutic procedure. It employs a combination of low-intensity ultrasound and chemical entities, known as a sonosensitizer, to produce cytotoxic reactive oxygen species (ROS) for cancer and antimicrobial therapies. With nanotechnology, several unique nanoplatforms are introduced as a sonosensitizers, including, titanium-based nanomaterials, thanks to their high biocompatibility, catalytic efficiency, and customizable physicochemical features. Additionally, developing titanium-based sonosensitizers facilitates the integration of SDT with other treatment modalities (for example, chemotherapy, chemodynamic therapy, photodynamic therapy, photothermal therapy, and immunotherapy), hence increasing overall therapeutic results. This review summarizes the most recent developments in cancer therapy and tissue engineering using titanium nanoplatforms mediated SDT. The synthesis strategies and biosafety aspects of Titanium-based nanoplatforms for SDT are also discussed. Finally, various challenges and prospects for its further development and potential clinical translation are highlighted.

Smart Nanosensitizers for Activatable Sono-Photodynamic Immunotherapy of Tumors by Redox-Controlled Disassembly

Tumor-targeted and stimuli-activatable nanosensitizers are highly desirable for cancer theranostics. However, designing smart nanosensitizers with multiple imaging signals and synergistic therapeutic activities switched on is challenging. Herein, we report tumor-targeted and redox-activatable nanosensitizers (1-NPs) for sono-photodynamic immunotherapy of tumors by molecular co-assembly and redox-controlled disassembly. 1-NPs show a high longitudinal relaxivity (r₁ =18.7±0.3 mM^-1  s^-1 ), but "off" dual fluorescence (FL) emission (at 547 and 672 nm), "off" sono-photodynamic therapy and indoleamine 2,3-dioxygenase 1 (IDO1) inhibition activities. Upon reduction by glutathione (GSH), 1-NPs rapidly disassemble and remotely release small molecules 2-Gd, Zn-PPA-SH and NLG919, concurrently switching on (1) dual FL emission, (2) sono-photodynamic therapy and (3) IDO1 inhibition activities. After systemic injection, 1-NPs are effective for bimodal FL and magnetic resonance (MR) imaging-guided sono-photodynamic immunotherapy of orthotropic breast and brain tumors in mice under combined ultrasound (US) and 671-nm laser irradiation.

A nanodrug combining CD47 and sonodynamic therapy efficiently inhibits osteosarcoma deterioration

Treatments for osteosarcoma (OS) with pulmonary metastases reach a bottleneck with a survival rate of 10-20%. The suppressive tumor associated macrophages(TAMs) and CD47 over-expression greatly lead to the treatment failure. Sonodynamic therapy (SDT) can generate ROS with deep tumor penetration to induce tumor cell apoptosis, which is reported to further induce M1 macrophage polarization. CD47 inhibition combined with SDT to synergistically modulate TAMs may induce superior effects for OS treatment. In this work, for the first time, a biomimetic nanodrug named MPIRx was deveploped by loading IR780 (a sonosensitizer) and RRx-001 (a CD47 inhibitor) in PEG-PCL nanomicelles and then coating with OS cell membranes. After ultrasound activation, the nanodrug significantly inhibited OS proliferation and migration, induced apoptosis and immunogenic cell death in OS cells. Furthermore, MPIRx could guide macrophage migrating towards tumor cells and promote M1-type polarization while increasing the phagocytosis activity of macrophages on OS cells. Ultimately, MPIRx showed good tumor accumulation in vivo and successfully inhibited subcutaneous OS and orthotopic tumor with deterioration of pulmonary metastasis. Overall, by creating a local oxidative microenvironment and modulating the TAMs/CD47 in tumor tissue, the MPIRx nanodrug presents a novel strategy for macrophage-related immunotherapy to successfully eliminate OS and inhibit the intractable pulmonary metastasis.

Imaging Guided Endogenic H2 -Augmented Electrochemo-Sonodynamic Domino Co-therapy of Tumor in Vivo

Precise and on-demand release of sufficient hydrogen (H₂ ) to tumor sites remains a key challenge for emerging H₂ -oncotherapy, and little is known about the physiological effects of "abundant" H₂ on complex tumor microenvironments (TME). Here, a highly efficient and cost-effective imaging-guided/-assessed H₂ -therapy of tumors based on a joint electrochemo-sonodynamic treatment (H₂ -EC/SD co-therapy) with strong "domino effect" triggered by endogenous H₂ generation at tumor sites is reported to speedily eliminate tumor tissue (≤80 mm³ ) within 1 day. Adequate H₂ is controllably generated in tumor sites through mild electrochemistry in vivo due to acidic TME by using clinical acupuncture Fe needles as electrodes. Besides starvation damage due to gas blockage/destruction of vessels, nano-/micro-bubbles of H₂ formed in situ can elevate the tumor's internal temperature and burst vessels to further destroy the tumor under ultrasound irradiation. Remarkably, vulnerable homeostasis of TME is disturbed as H₂ also participates in the physiological activity of tumor cells, leading to tumor dysfunction. Last but not least, the body's inflammatory response to cancer is reduced after the treatment, which is beneficial for the body's immune system during post-treatment recovery. Based on all of these merits, the H₂ -EC/SD co-therapy provides a potentially safe and viable therapeutic strategy for future clinical applications.

Protoporphyrin-sensitized degradable bismuth nanoformulations for enhanced sonodynamic oncotherapy

Decreasing the scavenging capacity of reactive oxygen species (ROS) and enhancing ROS production are the two principal objectives in the development of novel sonosensitizers for sonodynamic therapy (SDT). Herein, we designed a protoporphyrin-sensitized bismuth-based semiconductor (P-NBOF) as a sonosensitizer to generate ROS and synergistically depleted glutathione for enhanced SDT against tumors. The bismuth-based nanomaterial (NBOF) is a wide-bandgap semiconductor. Sensitization by protoporphyrin made it easier to excite electrons under ultrasonic stimulation, and the energy of the lowest unoccupied electron orbital in protoporphyrin was higher than the conduction-band energy of NBOF. Under ultrasound excitation, the excited electrons in the protoporphyrin were injected into the conduction band of the NBOF, increasing its reducing ability leading to the production of more superoxide anion radicals and also helping to increase the charge separation of protoporphyrin leading to the production of more singlet oxygen. Meanwhile, P-NBOF continuously depleted glutathione, which was not only conducive to breaking the redox balance of the tumor microenvironment to enhance the therapeutic efficacy of SDT, but also promoted its degradation and metabolism. The construction of this P-NBOF sonosensitizer thus provided an effective strategy to enhance SDT for tumors. STATEMENT OF SIGNIFICANCE: To enhance the efficacy of sonodynamic tumor therapy, we developed a degradable protoporphyrin-sensitized bismuth-based nano-semiconductor (P-NBOF) by optimizing the band structure and glutathione-depletion ability. Protoporphyrin in P-NBOF under excitation preferentially generates free electrons, which are then injected into the conduction band of NBOF, improving the reducing ability of NBOF and promoting the separation of electron-hole pairs, thereby enhancing the production capacity of reactive oxygen species. Furthermore, P-NBOF can deplete glutathione, reduce the scavenging of reactive oxygen species, and reactivate and amplify the effect of sonodynamic therapy. The construction of the nanotherapeutic platform provides an option for enhancing sonodynamic therapy.

Achieving Fast Charge Separation by Ferroelectric Ultrasonic Interfacial Engineering for Rapid Sonotherapy of Bacteria-Infected Osteomyelitis

Bacteria-infected osteomyelitis is life-threatening without effective therapeutic methods clinically. Here, a rapid and effective therapeutic strategy to treat osteomyelitis through ferroelectric polarization interfacial engineering of BiFeO₃ /MXene (Ti₃ C₂ ) triggered by ultrasound (US) is reported. Under US, the ferroelectric polarization induces the formation of the piezoelectric field. US cavitation effect induced sonoluminescence stimulates BiFeO₃ /Ti₃ C₂ to produce photogenerated carriers. With synergistic action of the polarization electric field and Schottky junction, BiFeO₃ /Ti₃ C₂ accelerates the separation of electrons and holes and simultaneously inhibits the backflow of electrons, thus improving the utilization of polarized charges and photogenerated charges and consequently enhancing the yield of reactive oxygen species under US. As a result, 99.87 ± 0.05% of Staphylococcus aureus are efficiently killed in 20 min with the assistance of ultrasonic heating. The theory of ferroelectric ultrasonic interfacial engineering is proposed, which brings new insight for developing ferroelectric ultrasonic responsive materials used for the diagnosis and therapy of deep tissue infection and other acoustoelectric devices.

Magneto-mechanical therapeutic effects and associated cell death pathways of magnetic nanocomposites with distinct geometries

Recent years have witnessed important developments in the emerging field of magneto-mechanical therapies. While such approaches have been demonstrated as a highly efficient route to augment, complement, or entirely replace other therapeutic strategies, important aspects are still poorly understood. Among these, the dependence between the cell death pathway and the geometry of magnetic nanocomposites enabling magneto-mechanical therapies under a low-frequency rotating magnetic field (RMF) is yet to be deciphered. To provide insights into this important problem, we evaluate the cell death pathway for two magnetic nanocomposites with highly distinct geometries: Zn_0.2Fe_2.8O₄-PLGA magnetic nanospheres (MNSs) and Zn_0.2Fe_2.8O₄-PLGA magnetic nanochains (MNCs). We show that under exposure to an RMF, the MNSs and the MNCs exhibit a corkscrewed circular propulsion mode and a steering propulsion mode, respectively. This distinct behavior, with important implications for the associated magneto-mechanical forces exerted by these nanomaterials on surrounding structures (e.g., the cellular membrane), depends on their specific geometries. Next, using numerical simulations and cell viability experiments, we demonstrate that the field strength of the RMF and the rotating speed of the MNSs or MNCs have strong implications for their magneto-mechanical therapeutic performance. Last, we reveal that the magneto-mechanical effects of MNSs are more prone to induce cell apoptosis, whereas those of the MNCs favor instead cell necrosis. Overall, this work enhances the current understanding of the dependences existing between the magneto-mechanical therapeutic effects of magnetic nanocomposites with different geometries and associated cell death pathways, paving the way for novel functionalization routes which could enable significantly enhanced cures and biomedical tools. STATEMENT OF SIGNIFICANCE.

Conjugation of Macrophage-Mimetic Microalgae and Liposome for Antitumor Sonodynamic Immunotherapy via Hypoxia Alleviation and Autophagy Inhibition

Sonodynamic therapy (SDT) is a noninvasive technique for local antitumor treatment; however, its clinical application is often limited by the low tumor accumulation of SDT agents, tumor's hypoxic microenvironment, and cytoprotective effects of autophagy. To address these issues, herein we developed surface-engineered chlorella (Chl, a green algae) as a targeted drug carrier and sustainable oxygen supplier (via photosynthesis) for significantly improved SDT via hypoxia alleviation as well as autophagy inhibition of chloroquine phosphate. In this design, the macrophage membrane was coated onto Chl to form macrophage-mimetic Chl (MChl) to increase its biocompatibility and targeted tumor accumulation driven by the inflammatory-homing effects of macrophage membranes. In addition, the membrane coating on Chl allowed lipid insertion to yield β-cyclodextrin (β-CD) modified MChl (CD-MChl). Subsequently, supramolecular conjugates of MChl-NP were constructed via host-guest interactions between CD-MChl and adamantane (ADA)-modified liposome (ADA-NP), and the anchored liposome went with CD-MChl hand-in-hand to the tumor tissues for co-delivery of Chl, hematoporphyrin, and chloroquine phosphate (loaded in ADA-NP). The synergistic therapy achieved via local oxygenation, SDT, and autophagy inhibition maximally improved the therapeutic efficacy of MChl-CQ-HP-NP against melanoma. Tumor rechallenging results revealed that the changes of tumor microenvironment including hypoxia alleviation, SDT induced immunogenic cell death, and autophagy inhibition collectively induced a strong antitumor immune response and memory.

Oxygen-Deficient Molybdenum Oxide Nanosensitizers for Ultrasound-Enhanced Cancer Metalloimmunotherapy

Oxygen-deficient molybdenum oxide (MoO_X ) nanomaterials are prepared as novel nanosensitizers and TME-stimulants for ultrasound (US)-enhanced cancer metalloimmunotherapy. After PEGylation, MoO_X -PEG exhibits efficient capability for US-triggered reactive oxygen species (ROS) generation and glutathione (GSH) depletion. Under US irradiation, MoO_X -PEG generates a massive amount of ROS to induce cancer cell damage and immunogenic cell death (ICD), which can effectively suppress tumor growth. More importantly, MoO_X -PEG itself further stimulates the maturation of dendritic cells (DCs) and triggeres the activation of the cGAS-STING pathway to enhance the immunological effect. Due to the robust ICD induced by SDT and efficient DC maturation stimulated by MoO_X -PEG, the combination treatment of MoO_X -triggered SDT and aCTLA-4 further amplifies antitumor therapy, inhibits cancer metastases, and elicits robust immune responses to effectively defeat abscopal tumors.

Defect-Rich Glassy IrTe2 with Dual Enzyme-Mimic Activities for Sono-Photosynergistic-Enhanced Oncotherapy

The complexity, diversity, and heterogeneity of malignant tumors pose a formidable challenge for antitumor therapy. To achieve the goal of significantly enhancing the antitumor effect, nanomedicine-based synergistic therapy is one of the important strategies. Herein, we innovatively report a defect-rich glassy IrTe2 (G-IrTe2) with weak Ir-Te bond strength for synergistic sonodynamic therapy (SDT), chemodynamic therapy (CDT), and mild photothermal therapy (PTT). G-IrTe2 sonosensitizer under ultrasound (US) stimuli exhibits excellent reactive oxygen species (ROS) production performance. Besides, catalase (CAT)-like activity of G-IrTe2 can provide abundant oxygen to enhance the SDT effect. Then, the theoretical calculation verifies that US stimuli can easily make the irregular Ir-Te bond to be broken in amorphous IrTe2 and free electrons will be released to combine with the oxygen and further form singlet oxygen (1O2). Meanwhile, G-IrTe2 with peroxidase (POD)-like activity can also catalyze endogenous H2O2 to produce more ROS for chemodynamic therapy (CDT), which is conducive to better tumor ablation. Furthermore, the ROS produced by sono-/chemodynamic processes can cause mitochondrial dysfunction and further give rise to heat shock protein (HSP) downregulated expression, maximizing the efficiency of mild PTT. Therefore, such glassy IrTe2 with rich defect could be significantly involved in synergistic oncotherapy and then effectively achieve outstanding antitumor efficacy. This study provides a new research idea for expanding the application of inorganic glassy nanomaterials in promoting the therapeutic effect of tumors.

Recent Advances in Well-Designed Therapeutic Nanosystems for the Pancreatic Ductal Adenocarcinoma Treatment Dilemma

Pancreatic ductal adenocarcinoma (PDAC) is a highly malignant tumor with an extremely poor prognosis and low survival rate. Due to its inconspicuous symptoms, PDAC is difficult to diagnose early. Most patients are diagnosed in the middle and late stages, losing the opportunity for surgery. Chemotherapy is the main treatment in clinical practice and improves the survival of patients to some extent. However, the improved prognosis is associated with higher side effects, and the overall prognosis is far from satisfactory. In addition to resistance to chemotherapy, PDAC is significantly resistant to targeted therapy and immunotherapy. The failure of multiple treatment modalities indicates great dilemmas in treating PDAC, including high molecular heterogeneity, high drug resistance, an immunosuppressive microenvironment, and a dense matrix. Nanomedicine shows great potential to overcome the therapeutic barriers of PDAC. Through the careful design and rational modification of nanomaterials, multifunctional intelligent nanosystems can be obtained. These nanosystems can adapt to the environment's needs and compensate for conventional treatments' shortcomings. This review is focused on recent advances in the use of well-designed nanosystems in different therapeutic modalities to overcome the PDAC treatment dilemma, including a variety of novel therapeutic modalities. Finally, these nanosystems' bottlenecks in treating PDAC and the prospect of future clinical translation are briefly discussed.

A robust Au@Cu2-xS nanoreactor assembled by silk fibroin for enhanced intratumoral glucose depletion and redox dyshomeostasis

Intracellular redox dyshomeostasis promoted by tumor microenvironment (TME) modulation has become an appealing therapeutic target for cancer management. Herein, a dual plasmonic Au/SF@Cu_2-xS nanoreactor (abbreviation as ASC) is elaborately developed by covalent immobilization of sulfur defective Cu_2-xS nanodots onto the surface of silk fibroin (SF)-capped Au nanoparticles. Tumor hypoxia can be effectively alleviated by ASC-mediated local oxygenation, owing to the newfound catalase-mimic activity of Cu_2-xS. The semiconductor of Cu_2-xS with narrow bandgap energy of 2.54 eV enables a more rapid dissociation of electron-hole (e^-/h⁺) pair for a promoted US-triggered singlet oxygen (¹O₂) generation, in the presence of Au as electron scavenger. Moreover, Cu_2-xS is devote to Fenton-like reaction to catalyze H₂O₂ into ·OH under mild acidity and simultaneously deplete glutathione to aggravate intracellular oxidative stress. In another aspect, Au nanoparticles with glucose oxidase-mimic activity consumes intrinsic glucose, which contributes to a higher degree of oxidative damage and energy exhaustion of cancer cells. Importantly, such tumor starvation and ¹O₂ yield can be enhanced by Cu_2-xS-catalyzed O₂ self-replenishment in H₂O₂-rich TME. ASC-initiated M1 macrophage activation and therapy-triggered immunogenetic cell death (ICD) favors the systematic tumor elimination by eliciting antitumor immunity. This study undoubtedly enriches the rational design of SF-based nanocatalysts for medical utilizations.

Covalent Organic Framework Nanobowls as Activatable Nanosensitizers for Tumor-Specific and Ferroptosis-Augmented Sonodynamic Therapy

Covalent organic frameworks (COFs) have attracted increasing attention for biomedical applications. COFs-based nanosensitizers with uniform nanoscale morphology and tumor-specific curative effects are in high demand; however, their synthesis is yet challenging. In this study, distinct COF nanobowls are synthesized in a controlled manner and engineered as activatable nanosensitizers with tumor-specific sonodynamic activity. High crystallinity ensures an ordered porous structure of COF nanobowls for the efficient loading of the small-molecule sonosensitizer rose bengal (RB). To circumvent non-specific damage to normal tissues, the sonosensitization effect is specifically inhibited by the in situ growth of manganese oxide (MnOx ) on RB-loaded COFs. Upon reaction with tumor-overexpressed glutathione (GSH), the "gatekeeper" MnOx is rapidly decomposed to recover the reactive oxygen species (ROS) generation capability of the COF nanosensitizers under ultrasound irradiation. Increased intracellular ROS stress and GSH consumption concomitantly induce ferroptosis to improve sonodynamic efficacy. Additionally, the unconventional bowl-shaped morphology renders the nanosensitizers with enhanced tumor accumulation and retention. The combination of tumor-specific sonodynamic therapy and ferroptosis achieves high efficacy in killing cancer cells and inhibiting tumor growth. This study paves the way for the development of COF nanosensitizers with unconventional morphologies for biomedicine, offering a paradigm to realize activatable and ferroptosis-augmented sonodynamic tumor therapy.

Integration of Silica Nanorattles with Manganese-Doped In2S3/InOOH to Enable Ultrasound-Mediated Tumor Theranostics

As a result of their radiation-free nature and deep-penetration ability, tumor theranostics mediated by ultrasound have become increasingly recognized as a modality with high potential for translation into clinical cancer treatment. The effective integration of ultrasound imaging and sonodynamic therapy (SDT) into one nanoplatform remains an enormous challenge yet to be fully resolved. Here, a novel theranostic system, consisting of rattle-type SiO₂ (r-SiO₂) loaded with Mn-doped In₂S₃/InOOH (SMISO), was designed and synthesized to enable an improved ultrasound imaging-guided therapy. With Mn-doped In₂S₃/InOOH (MISO) and a heterojunction structure, this novel sonosensitizer facilitates the generation of reactive oxygen species (ROS) for SDT. By coupling interfaces between the shell and core in rattle-type SiO₂, multiple reflections/scattering are generated, while MISO has high acoustic impedance. By integrating r-SiO₂ and MISO, the SMISO composite nanoparticles (NPs) increase the acoustic reflection and provide enhanced contrast for ultrasound imaging. Through the effective accumulation in tumors, which was monitored by B-mode ultrasound imaging in vivo, SMISO composite NPs effectively inhibited tumor growth without adverse side effects under ultrasound irradiation treatment. This work therefore provides a new approach to integrate a novel gas-free ultrasound contrast agent and a semiconductor sonosensitizer for cancer theranostics.

Multifunctional nanoparticle for cancer therapy

Cancer is a complex disease associated with a combination of abnormal physiological process and exhibiting dysfunctions in multiple systems. To provide effective treatment and diagnosis for cancer, current treatment strategies simultaneously focus on various tumor targets. Based on the rapid development of nanotechnology, nanocarriers have been shown to exhibit excellent potential for cancer therapy. Compared with nanoparticles with single functions, multifunctional nanoparticles are believed to be more aggressive and potent in the context of tumor targeting. However, the development of multifunctional nanoparticles is not simply an upgraded version of the original function, but involves a sophisticated system with a proper backbone, optimized modification sites, simple preparation method, and efficient function integration. Despite this, many well-designed multifunctional nanoparticles with promising therapeutic potential have emerged recently. Here, to give a detailed understanding and analyzation of the currently developed multifunctional nanoparticles, their platform structures with organic or inorganic backbones were systemically generalized. We emphasized on the functionalization and modification strategies, which provide additional functions to the nanoparticle. We also discussed the application combination strategies that were involved in the development of nanoformulations with functional crosstalk. This review thus provides an overview of the construction strategies and application advances of multifunctional nanoparticles.

Ferroptosis: challenges and opportunities for nanomaterials in cancer therapy

Ferroptosis, a completely new form of regulated cell death, is mainly caused by an imbalance between oxidative damage and reductive protection and has shown great anti-cancer potential. However, existing small-molecule ferroptosis inducers have various limitations, such as poor water solubility, drug resistance and low targeting ability, hindering their clinical applications. Nanotechnology provides new opportunities for ferroptosis-driven tumor therapy. Especially, stimuli-responsive nanomaterials stand out among others and have been widely researched because of their unique spatiotemporal control advantages. Therefore, it's necessary to summarize the application of those stimuli-responsive nanomaterials in ferroptosis. Here, we describe the physiological feature of ferroptosis and illustrate the current challenges to induce ferroptosis for cancer therapy. Then, nanomaterials that induce ferroptosis are classified and elaborated according to the external and internal stimuli. Finally, the future perspectives in the field are proposed. We hope this review facilitates paving the way for the design of intelligent nano-ferroptosis inducers.

Piezocatalytic Medicine: An Emerging Frontier using Piezoelectric Materials for Biomedical Applications

Emerging piezocatalysts have demonstrated their remarkable application potential in diverse medical fields. In addition to their ultrahigh catalytic activities, their inherent and unique charge-carrier-releasing properties can be used to initiate various redox catalytic reactions, displaying bright prospects for future medical applications. Triggered by mechanical energy, piezocatalytic materials can release electrons/holes, catalyze redox reactions of substrates, or intervene in biological processes to promote the production of effector molecules for medical purposes, such as decontamination, sterilization, and therapy. Such a medical application of piezocatalysis is termed as piezocatalytic medicine (PCM) herein. To pioneer novel medical technologies, especially therapeutic modalities, this review provides an overview of the state-of-the-art research progress in piezocatalytic medicine. First, the principle of piezocatalysis and the preparation methodologies of piezoelectric materials are introduced. Then, a comprehensive summary of the medical applications of piezocatalytic materials in tumor treatment, antisepsis, organic degradation, tissue repair and regeneration, and biosensing is provided. Finally, the main challenges and future perspectives in piezocatalytic medicine are discussed and proposed, expecting to fuel the development of this emerging scientific discipline.

Acidity-Biodegradable Iridium-Coordinated Nanosheets for Amplified Ferroptotic Cell Death Through Multiple Regulatory Pathways

Ferroptosis-based treatment strategies display the potential to suppress some malignant tumors with intrinsic apoptosis resistance. However, current related cancer treatments are still hampered by insufficient intracellular reactive oxygen species (ROS) levels and Fe²⁺ contents, posing considerable challenges for their clinical translation. Herein, an intracellular acid-biodegradable iridium-coordinated nanosheets (Ir-Hemin) with sonodynamic therapy (SDT) properties to effectively induce ferroptosis in tumor cells through multiple regulatory pathways are proposed. Under ultrasound (US) irradiation, Ir-Hemin nanosheets act as nanosonosensitizers to effectively generate ROS, subsequently causing the accumulation of lipid peroxides (LPO) and inducing ferroptotic cell death. Furthermore, these Ir-Hemin nanosheets decompose quickly to release hemin and Ir(IV), which deplete intracellular glutathione (GSH) to deactivate the enzyme glutathione peroxidase 4 (GPX4) and initiate the ferroptosis pathway. Specifically, the released hemin enables heme oxygenase 1 (HO-1) upregulation for endogenous ferrous ion supplementation, which compensates for the toxicity concerns brought about by the large uptake of exogenous iron. Surprisingly, Ir-Hemin nanosheets exhibit high tumor accumulation and trigger effective ferroptosis for tumor therapy. These Ir-Hemin nanosheets display pronounced synergistic anticancer efficacy under US stimulation both in vitro and in vivo, providing a strong rationale for the application of ferroptosis in cancer treatment.

Ultrasound nanotheranostics: Toward precision medicine

Ultrasound (US) is a mechanical wave that can penetrate biological tissues and trigger complex bioeffects. The mechanisms of US in different diagnosis and treatment are different, and the functional application of commercial US is also expanding. In particular, recent developments in nanotechnology have led to a wider use of US in precision medicine. In this review, we focus on US in combination with versatile micro and nanoparticles (NPs)/nanovesicles for tumor theranostics. We first introduce US-assisted drug delivery as a stimulus-responsive approach that spatiotemporally regulates the deposit of nanomedicines in target tissues. Multiple functionalized NPs and their US-regulated drug-release curves are analyzed in detail. Moreover, as a typical representative of US therapy, sonodynamic antitumor strategy is attracting researchers' attention. The collaborative efficiency and mechanisms of US and various nano-sensitizers such as nano-porphyrins and organic/inorganic nanosized sensitizers are outlined in this paper. A series of physicochemical processes during ultrasonic cavitation and NPs activation are also discussed. Finally, the new applications of US and diagnostic NPs in tumor-monitoring and image-guided combined therapy are summarized. Diagnostic NPs contain substances with imaging properties that enhance US contrast and photoacoustic imaging. The development of such high-resolution, low-background US-based imaging methods has contributed to modern precision medicine. It is expected that the integration of non-invasive US and nanotechnology will lead to significant breakthroughs in future clinical applications.