Defect modified zinc oxide with augmenting sonodynamic reactive oxygen species generation

Tuning molecular assembly behavior to amplify the sonodynamic activity of porphyrins for efficient antibacterial therapy

Sonodynamic therapy (SDT) is a promising strategy to treat deep-seated bacterial infections with good tissue penetration and spatiotemporal controllability. However, the low ROS generation efficiency of current sonosensitizers limits the development of SDT. Herein, we report a porphyrin derivative, TAPyPP-2, the sonodynamic activity of which is enhanced with less oxygen dependence by tuning its molecular assembly behavior. TAPyPP-2 can spontaneously form an ultra-small nano-assembly with a diameter of 6 nm in water by conjugation with primary amine salt-decorated pyridinium via π-π staking. The ultra-small assembly behavior can lower the energy gap between singlet and triplet states to 0.01 eV and promote the separation of holes and electrons, which facilitates ROS generation under ultrasound irradiation, in particular type I ROS. The unique hydrophilic ratio and positive charges endow TAPyPP-2 with superior abilities to interact with Staphylococcus aureus, resulting in extremely high sonodynamic antibacterial activity. Therefore, TAPyPP-2 successfully kills Staphylococcus aureus bacteria in the enclosed cavity of synovial joint and achieves effective SDT of septic arthritis. This work is anticipated to motivate enormous interest in the development of efficient SDT.

Surface Oxygen Vacancies and Corona Polarization of Bi4Ti3O12 Nanosheets for Synergistically Enhanced Sonopiezoelectric Therapy

Sonopiezoelectric therapy, an ultrasound-activated piezoelectric nanomaterial for tumor treatment, has emerged as a novel alternative modality. However, the limited piezoelectric catalytic efficiency is a serious bottleneck for its practical application. Excellent piezoelectric catalysts with high piezoelectric coefficients, good deformability, large mechanical impact surface area, and abundant catalytically active sites still need to be developed urgently. In this study, the classical ferroelectric material, bismuth titanate (Bi4Ti3O12, BTO), is selected as a sonopiezoelectric sensitizer for tumor therapy. BTO generates electron-hole pairs under ultrasonic irradiation, which can react with the substrates in a sonocatalytic-driven redox reaction. Aiming to further improve the catalytic activity of BTO, modification of surface oxygen vacancies and treatment of corona polarization are envisioned in this study. Notably, modification of the surface oxygen vacancies reduces its bandgap and inhibits electron-hole recombination. Additionally, the corona polarization treatment immobilized the built-in electric field on BTO, further promoting the separation of electrons and holes. Consequently, these modifications greatly improve the sonocatalytic efficiency for in situ generation of cytotoxic ROS and CO, effectively eradicating the tumor.

Ternary Bi2WO6/TiO2-Pt Heterojunction Sonosensitizers for Boosting Sonodynamic Therapy

Engineering Z-scheme heterojunctions represents a promising strategy for optimizing the separation and migration of charge carriers in semiconductor sonosensitizers for enhanced reactive oxygen species (ROS) generation. Nevertheless, establishing a continuous and directional pathway for ultrasonic-induced charge flow in Z-scheme heterojunctions remains a significant challenge. In this study, we present a ternary Bi2WO6/TiO2-Pt heterojunction sonosensitizer achieved through the precise growth of Pt nanocrystals on a directionally assembled Bi2WO6/TiO2 Z-scheme structure. The construction of the Bi2WO6/TiO2-Pt heterojunction involves directional growth of Bi2WO6 in situ on the highly exposed (001) crystal facet of TiO2 nanosheets, followed by the precise deposition of nano Pt on the edge (101) crystal facet. The Z-scheme Bi2WO6/TiO2 in the ternary heterojunction ensures effective electron separation, while the Schottky TiO2-Pt interface establishes a well-defined charge flow path and robust redox capabilities. Moreover, nano Pt confers the Bi2WO6/TiO2-Pt heterojunction with excellent peroxidase-mimic and catalase-mimic activities, facilitating interactions with endogenous H2O2 to produce the hydroxyl radicals and O2. It effectively alleviates tumor hypoxia and enhances ROS production. This results in significantly higher efficiency in sonodynamically induced ROS generation compared to pure TiO2 or binary Bi2WO6/TiO2 heterojunctions, as confirmed by DFT theoretical calculation and experiments with both in vitro and in vivo anticancer performance. This study offers valuable insights for designing high-performance Z-scheme sonosensitizer systems.

Sulfur-Vacancy-Engineered Two-Dimensional Cu@SnS2-x Nanosheets Constructed via Heterovalent Substitution for High-Efficiency Piezocatalytic Tumor Therapy

Ultrasound (US)-mediated piezocatalytic tumor therapy has attracted much attention due to its notable tissue-penetration capabilities, noninvasiveness, and low oxygen dependency. Nevertheless, the efficiency of piezocatalytic therapy is limited due to an inadequate piezoelectric response, low separation of electron-hole (e--h+) pairs, and complex tumor microenvironment (TME). Herein, an ultrathin two-dimensional (2D) sulfur-vacancy-engineered (Sv-engineered) Cu@SnS2-x nanosheet (NS) with an enhanced piezoelectric effect was constructed via the heterovalent substitution strategy of Sn4+ by Cu2+. The introduction of Cu2+ ion not only causes changes in the crystal structure to increase polarization but also generates rich Sv to decrease band gap from 2.16 to 1.62 eV and inhibit e--h+ pairs recombination, collectively leading to the highly efficient generation of reactive oxygen species under US irradiation. Moreover, Cu@SnS2-x shows US-enhanced TME-responsive Fenton-like catalytic activity and glutathione depletion ability, further aggravating the oxidative stress. Both in vitro and in vivo results prove that the Sv-engineered Cu@SnS2-x NSs can significantly kill tumor cells and achieve high-efficiency piezocatalytic tumor therapy in a biocompatible manner. Overall, this study provides a new avenue for sonocatalytic therapy and broadens the application of 2D piezoelectric materials.

Recent Progress in Photothermal, Photodynamic and Sonodynamic Cancer Therapy: Through the cGAS-STING Pathway to Efficacy-Enhancing Strategies

Photothermal, photodynamic and sonodynamic cancer therapies offer opportunities for precise tumor ablation and reduce side effects. The cyclic guanylate adenylate synthase-stimulator of interferon genes (cGAS-STING) pathway has been considered a potential target to stimulate the immune system in patients and achieve a sustained immune response. Combining photothermal, photodynamic and sonodynamic therapies with cGAS-STING agonists represents a newly developed cancer treatment demonstrating noticeable innovation in its impact on the immune system. Recent reviews have concentrated on diverse materials and their function in cancer therapy. In this review, we focus on the molecular mechanism of photothermal, photodynamic and sonodynamic cancer therapies and the connected role of cGAS-STING agonists in treating cancer.

MOF-Derived Nanoparticles with Enhanced Acoustical Performance for Efficient Mechano-Sonodynamic Therapy

Ultrasound (US) generates toxic reactive oxygen species (ROS) by acting on sonosensitizers for cancer treatment, and the mechanical damage induced by cavitation effects under US is equally significant. Therefore, designing a novel sonosensitizer that simultaneously possesses efficient ROS generation and enhanced mechanical effects is promising. In this study, carbon-doped zinc oxide nanoparticles (C-ZnO) are constructed for mechano-sonodynamic cancer therapy. The presence of carbon (C) doping optimizes the electronic structure, thereby enhancing the ROS generation triggered by US, efficiently inducing tumor cell death. On the other hand, the high specific surface area and porous structure brought about by C doping enable C-ZnO to enhance the mechanical stress induced by cavitation bubbles under US irradiation, causing severe mechanical damage to tumor cells. Under the dual effects of sonodynamic therapy (SDT) and mechanical therapy mediated by C-ZnO, excellent anti-tumor efficacy is demonstrated both in vitro and in vivo, along with a high level of biological safety. This is the first instance of utilizing an inorganic nanomaterial to achieve simultaneous enhancement of ROS production and US-induced mechanical effects for cancer therapy. This holds significant importance for the future development of novel sonosensitizers and advancing the applications of US in cancer treatment.

Oxygen-defect bismuth oxychloride nanosheets for ultrasonic cavitation effect enhanced sonodynamic and second near-infrared photo-induced therapy of breast cancer

Sonodynamic therapy (SDT) relies heavily on the presence of oxygen to induce cell death. Its effectiveness is thus diminished in the hypoxic regions of tumor tissue. To address this issue, the exploration of ultrasound-based synergistic treatment modalities has become a significant research focus. Here, we report an ultrasonic cavitation effect enhanced sonodynamic and 1208 nm photo-induced cancer treatment strategy based on thermoelectric/piezoelectric oxygen-defect bismuth oxychloride nanosheets (BNs) to realize the high-performance eradication of tumors. Upon ultrasonic irradiation, the local high temperature and high pressure generated by the ultrasonic cavitation effect combined with the thermoelectric and piezoelectric effects of BNs create a built-in electric field. This facilitates the separation of carriers, increasing their mobility and extending their lifetimes, thereby greatly improving the effectiveness of SDT and NIR-Ⅱ phototherapy on hypoxia. The Tween-20 modified BNs (TBNs) demonstrate ∼88.6 % elimination rate against deep-seated tumor cells under hypoxic conditions. In vivo experiments confirm the excellent antitumor efficacy of TBNs, achieving complete tumor elimination within 10 days with no recurrences. Furthermore, due to the high X-ray attenuation of Bi and excellent NIR-Ⅱ absorption, TBNs enable precise cancer diagnosis through photoacoustic (PA) imaging and computed tomography (CT).

Tumour microenvironment-responded Fe-doped carbon dots-sensitized cubic Cu2O for Z-scheme heterojunction-enhanced sono-chemodynamic synergistic tumor therapy

The efficacy of electron-hole separation in a single sonosensitizer and the complexities of the tumor microenvironment (TME) present significant challenges to the effectiveness of sonodynamic therapy (SDT). Designing efficient sonosensitizers to enhance electron-hole separation and alleviate TME resistance is crucial yet challenging. Herein, we introduce a novel Z-scheme heterojunctions (HJs) sonosensitizer using Fe-doped carbon dots (CDs) as auxiliary semiconductors to sensitize cubic Cu2O (Fe-CDs@Cu2O) for the first time. Fe-CDs@Cu2O demonstrated enhanced SDT effects due to improved electron-hole separation. Additionally, the introduction of Fe ions in CDs synergistically enhances Fenton-like reactions with Cu ions in Cu2O, resulting in enhanced chemodynamic therapy (CDT) effects. Moreover, Fe-CDs@Cu2O exhibited rapid glutathione (GSH) depletion, effectively mitigating TME resistance. With high rates of 1O2 and OH generated by Fe-CDs@Cu2O, coupled with strong GSH depletion, single drug injection and ultrasound (US) irradiation effectively eliminate tumors. This innovative heterojunction sonosensitizer offers a promising pathway for clinical anti-tumor treatment.

Radioactive hybrid semiconducting polymer nanoparticles for imaging-guided tri-modal therapy of breast cancer

Due to the rapid progression and aggressive metastasis of breast cancer, its diagnosis and treatment remain a great challenge. The simultaneous inhibition of tumor growth and metastasis is necessary for breast cancer to obtain ideal therapeutic outcomes. We herein report the development of radioactive hybrid semiconducting polymer nanoparticles (SPNH) for imaging-guided tri-modal therapy of breast cancer. Two semiconducting polymers are used to form SPNH with a diameter of around 60 nm via nano-coprecipitation and they are also labeled with iodine-131 (131I) to enhance the imaging functions. The formed SPNH show good radiolabeling stability and excellent photodynamic and photothermal effects under 808 nm laser irradiation to produce singlet oxygen (1O2) and heat. Moreover, SPNH can generate 1O2 with ultrasound irradiation via their sonodynamic properties. After intravenous tail vein injection, SPNH can effectively accumulate in the subcutaneous 4T1 tumors of living mice as verified via fluorescence and single photon emission computed tomography (SPECT) imaging. With the irradiation of tumors using an 808 nm laser and US, SPNH mediate photodynamic therapy (PDT), photothermal therapy (PTT) and sonodynamic therapy (SDT) to kill tumor cells. Such a tri-modal therapy leads to an improved efficacy in inhibiting tumor growth and suppressing tumor metastasis compared to the sole SDT and combinational PDT-PTT. This study thus demonstrates the applications of SPNH to diagnose tumors and combine different therapies for effective breast cancer treatment.

A Distinctive Insight into Inorganic Sonosensitizers: Design Principles and Application Domains

Sonodynamic therapy (SDT) as a promising non-invasive anti-tumor means features the preferable penetration depth, which nevertheless, usually can't work without sonosensitizers. Sonosensitizers produce reactive oxygen species (ROS) in the presence of ultrasound to directly kill tumor cells, and concurrently activate anti-tumor immunity especially after integration with tumor microenvironment (TME)-engineered nanobiotechnologies and combined therapy. Current sonosensitizers are classified into organic and inorganic ones, and current most reviews only cover organic sonosensitizers and highlighted their anti-tumor applications. However, there have few specific reviews that focus on inorganic sonosensitizers including their design principles, microenvironment regulation, etc. In this review, inorganic sonosensitizers are first classified according to their design rationales rather than composition, and the action rationales and underlying chemistry features are highlighted. Afterward, what and how TME is regulated based on the inorganic sonosensitizers-based SDT nanoplatform with an emphasis on the TME targets-engineered nanobiotechnologies are elucidated. Additionally, the combined therapy and their applications in non-cancer diseases are also outlined. Finally, the setbacks and challenges, and proposed the potential solutions and future directions is pointed out. This review provides a comprehensive and detailed horizon on inorganic sonosensitizers, and will arouse more attentions on SDT.

NIR-II light in clinical oncology: opportunities and challenges

Novel strategies utilizing light in the second near-infrared region (NIR-II; 900-1,880 nm wavelengths) offer the potential to visualize and treat solid tumours with enhanced precision. Over the past few decades, numerous techniques leveraging NIR-II light have been developed with the aim of precisely eliminating tumours while maximally preserving organ function. During cancer surgery, NIR-II optical imaging enables the visualization of clinically occult lesions and surrounding vital structures with increased sensitivity and resolution, thereby enhancing surgical quality and improving patient prognosis. Furthermore, the use of NIR-II light promises to improve cancer phototherapy by enabling the selective delivery of increased therapeutic energy to tissues at greater depths. Initial clinical studies of NIR-II-based imaging and phototherapy have indicated impressive potential to decrease cancer recurrence, reduce complications and prolong survival. Despite the encouraging results achieved, clinical translation of innovative NIR-II techniques remains challenging and inefficient; multidisciplinary cooperation is necessary to bridge the gap between preclinical research and clinical practice, and thus accelerate the translation of technical advances into clinical benefits. In this Review, we summarize the available clinical data on NIR-II-based imaging and phototherapy, demonstrating the feasibility and utility of integrating these technologies into the treatment of cancer. We also introduce emerging NIR-II-based approaches with substantial potential to further enhance patient outcomes, while also highlighting the challenges associated with imminent clinical studies of these modalities.

Ultrasound-Triggered Piezoelectric Catalysis of Zinc Oxide@Glucose Derived Carbon Spheres for the Treatment of MRSA Infected Osteomyelitis

Currently, methicillin-resistant Staphylococcus aureus (MRSA)-induced osteomyelitis is a clinically life-threatening disease, however, long-term antibiotic treatment can lead to bacterial resistance, posing a huge challenge to treatment and public health. In this study, glucose-derived carbon spheres loaded with zinc oxide (ZnO@HTCS) are successfully constructed. This composite demonstrates the robust ability to generate reactive oxygen species (ROS) under ultrasound (US) irradiation, eradicating 99.788% ± 0.087% of MRSA within 15 min and effectively treating MRSA-induced osteomyelitis infection. Piezoelectric force microscopy tests and finite element method simulations reveal that the ZnO@HTCS composite exhibits superior piezoelectric catalytic performance compared to pure ZnO, making it a unique piezoelectric sonosensitizer. Density functional theory calculations reveal that the formation of a Mott-Schottky heterojunction and an internal piezoelectric field within the interface accelerates the electron transfer and the separation of electron-hole pairs. Concurrently, surface vacancies of the composite enable the adsorption of a greater amount of oxygen, enhancing the piezoelectric catalytic effect and generating a substantial quantity of ROS. This work not only presents a promising approach for augmenting piezoelectric catalysis through construction of a Schottky heterojunction interface but also provides a novel, efficient therapeutic strategy for treating osteomyelitis.

Revealing the Optimization Route of Piezoelectric Sonosensitizers: From Mechanism to Engineering Methods

Piezoelectric catalysis is a novel catalytic technology that has developed rapidly in recent years and has attracted extensive interest among researchers in the field of tumor therapy for its acoustic-sensitizing properties. Nevertheless, researchers are still controversial about the key technical difficulties in the modulation of piezoelectric sonosensitizers for tumor therapy applications, which is undoubtedly a major obstacle to the performance modulation of piezoelectric sonosensitizers. Clarification of this challenge will be beneficial to the design and optimization of piezoelectric sonosensitizers in the future. Here, the authors start from the mechanism of piezoelectric catalysis and elaborate the mechanism and methods of defect engineering and phase engineering for the performance modulation of piezoelectric sonosensitizers based on the energy band theory. The combined therapeutic strategy of piezoelectric sonosensitizers with enzyme catalysis and immunotherapy is introduced. Finally, the challenges and prospects of piezoelectric sonosensitizers are highlighted. Hopefully, the explorations can guide researchers toward the optimization of piezoelectric sonosensitizers and can be applied in their own research.

Graphene Quantum Dots Nanoantibiotic-Sensitized TiO2- x Heterojunctions for Sonodynamic-Nanocatalytic Therapy of Multidrug-Resistant Bacterial Infections

The exploration of sonodynamic therapy (SDT) as a possible replacement for antibiotics by creating reactive oxygen species (ROS) is suggested as a non-drug-resistant theranostic method. However, the low-efficiency ROS generation and complex tumor microenvironment which can deplete ROS and promote tumor growth will cause the compromised antibacterial efficacy of SDT. Herein, through an oxygen vacancy engineering strategy, TiO2- x microspheres with an abundance of Ti3+ are synthesized using a straightforward reductant co-assembly approach. The narrow bandgaps and Ti3+/Ti4+-mediated multiple-enzyme catalytic activities of the obtained TiO2- x microspheres make them suitable for use as sonosensitizers and nanozymes. When graphene quantum dot (GQD) nanoantibiotics are deposited on TiO2- x microspheres, the resulting GQD/TiO2- x shows an increased production of ROS, which can be ascribed to the accelerated separation of electron-hole pairs, as well as the peroxidase-like catalytic activity mediated by Ti3+, and the depletion of glutathione mediated by Ti4+. Moreover, the catalytic activities of TiO2- x microspheres are amplified by the heterojunctions-accelerated carrier transfer. In addition, GQDs can inhibit Topo I, displaying strong antibacterial activity and further enhancing the antibacterial activity. Collectively, the combination of GQD/TiO2- x-mediated SDT/NCT with nanoantibiotics can result in a synergistic effect, allowing for multimodal antibacterial treatment that effectively promotes wound healing.

Defect-rich sonosensitizers based on CeO2 with Schottky heterojunctions for boosting sonodynamic/chemodynamic synergistic therapy

Sonodynamic therapy (SDT) has been recognized as a promising treatment for cancer due to its advantages of superior specificity, non-invasiveness, and deep tissue penetration. However, the antitumor effect of SDT remains restricted by the limited generation of reactive oxygen species (ROS) due to the lack of highly efficient sonosensitizers. In this work, we developed the novel sonosensitizer Pt/CeO2-xSx by constructing oxygen defects through S doping and Pt loading in situ. Large amounts of oxygen defects have been obtained by S doping, endowing Pt/CeO2-xSx with the ability to suppress electron-hole recombination, further promoting ROS production. Moreover, the introduction of Pt nanoparticles can not only produce oxygen in situ for relieving hypoxia but also form a Schottky heterojunction with CeO2-xSx for further inhibiting electron-hole recombination. In addition, Pt/CeO2-xSx could effectively deplete overexpressed glutathione (GSH) via redox reactions, amplifying oxidative stress in the tumor microenvironment (TME). Combined with the excellent POD-mimetic activity, Pt/CeO2-xSx can achieve highly efficient synergistic therapy of SDT and chemodynamic therapy (CDT). All these findings demonstrated that Pt/CeO2-xSx has great potential for cancer therapy, and this work provides a promising direction for designing and constructing efficient sonosensitizers.

Defect-Repaired g-C3N4 Nanosheets: Elevating the Efficacy of Sonodynamic Cancer Therapy Through Enhanced Charge Carrier Migration

Sonodynamic therapy (SDT) has garnered growing interest owing to its high tissue penetration depth and minimal side effects. However, the lack of efficient sonosensitizers remains the primary limiting factor for the clinical application of this treatment method. Here, defect-repaired graphene phase carbon nitride (g-C3N4) nanosheets are prepared and utilized for enhanced SDT in anti-tumor treatment. After defect engineering optimization, the bulk defects of g-C3N4 are significantly reduced, resulting in higher crystallinity and exhibiting a polyheptazine imide (PHI) structure. Due to the more extended conjugated structure of PHI, facilitating faster charge transfer on the surface, it exhibits superior SDT performance for inducing apoptosis in tumor cells. This work focuses on introducing a novel carbon nitride nanomaterial as a sonosensitizer and a strategy for optimizing sonosensitizer performance by reducing bulk defects.

Application and progress of nanozymes in antitumor therapy

Tumors remain one of the major threats to public health and there is an urgent need to design new pharmaceutical agents for their diagnosis and treatment. In recent years, due to the rapid development of nanotechnology, biotechnology, catalytic science, and theoretical computing, subtlety has gradually made great progress in research related to tumor diagnosis and treatment. Compared to conventional drugs, enzymes can improve drug distribution and enhance drug enrichment at the tumor site, thereby reducing drug side effects and enhancing drug efficacy. Nanozymes can also be used as tumor tracking imaging agents to reshape the tumor microenvironment, providing a versatile platform for the diagnosis and treatment of malignancies. In this paper, we review the current status of research on enzymes in oncology and analyze novel oncology therapeutic approaches and related mechanisms. To date, a large number of nanomaterials, such as noble metal nanomaterials, nonmetallic nanomaterials, and carbon-based nanomaterials, have been shown to be able to function like natural enzymes, particularly with significant advantages in tumor therapy. In light of this, the authors in this review have systematically summarized and evaluated the construction, enzymatic activity, and their characteristics of nanozymes with respect to current modalities of tumor treatment. In addition, the application and research progress of different types of nicknames and their features in recent years are summarized in detail. We conclude with a summary and outlook on the study of nanozymes in tumor diagnosis and treatment. It is hoped that this review will inspire researchers in the fields of nanotechnology, chemistry, biology, materials science and theoretical computing, and contribute to the development of nano-enzymology.

Piezo-enhanced near infrared photocatalytic nanoheterojunction integrated injectable biopolymer hydrogel for anti-osteosarcoma and osteogenesis combination therapy

Preventing local tumor recurrence while promoting bone tissue regeneration is an urgent need for osteosarcoma treatment. However, the therapeutic efficacy of traditional photosensitizers is limited, and they lack the ability to regenerate bone. Here, a piezo-photo nanoheterostructure is developed based on ultrasmall bismuth/strontium titanate nanocubes (denoted as Bi/SrTiO3), which achieve piezoelectric field-driven fast charge separation coupling with surface plasmon resonance to efficiently generate reactive oxygen species. These hybrid nanotherapeutics are integrated into injectable biopolymer hydrogels, which exhibit outstanding anticancer effects under the combined irradiation of NIR and ultrasound. In vivo studies using patient-derived xenograft models and tibial osteosarcoma models demonstrate that the hydrogels achieve tumor suppression with efficacy rates of 98.6 % and 67.6 % in the respective models. Furthermore, the hydrogel had good filling and retention capabilities in the bone defect region, which exerted bone repair therapeutic efficacy by polarizing and conveying electrical stimuli to the cells under mild ultrasound radiation. This study provides a comprehensive and clinically feasible strategy for the overall treatment and tissue regeneration of osteosarcoma.

Nanomedicine/materdicine-enabled sonocatalytic therapy

The advent of numerous treatment modalities with desirable therapeutic efficacy has been made possible by the fast development of nanomedicine and materdicine, among which the ultrasound (US)-triggered sonocatalytic process as minimal or non-invasive method has been frequently employed for diagnostic and therapeutic purposes. In comparison to phototherapeutic approaches with inherent penetration depth limitations, sonocatalytic therapy shatters the depth limit of photoactivation and offers numerous remarkable prospects and advantages, including mitigated side effects and appropriate tissue-penetration depth. Nevertheless, the optimization of sonosensitizers and therapies remains a significant issue in terms of precision, intelligence and efficiency. In light of the fact that nanomedicine and materdicine can effectively enhance the theranostic efficiency, we herein aim to furnish a cutting-edge review on the latest progress and development of nanomedicine/materdicine-enabled sonocatalytic therapy. The design methodologies and biological features of nanomedicine/materdicine-based sonosensitizers are initially introduced to reveal the underlying relationship between composition/structure, sonocatalytic function and biological effect, in accompany with a thorough discussion of nanomedicine/materdicine-enabled synergistic therapy. Ultimately, the facing challenges and future perspectives of this intriguing sonocatalytic therapy are highlighted and outlined to promote technological advancements and clinical translation in efficient disease treatment.

Multifunctional ZnO@DOX/ICG-LMHP Nanoparticles for Synergistic Multimodal Antitumor Activity

Multifunctional nanoparticles are of significant importance for synergistic multimodal antitumor activity. Herein, zinc oxide (ZnO) was used as pH-sensitive nanoparticles for loading the chemotherapy agent doxorubicin (DOX) and the photosensitizer agent indocyanine green (ICG), and biocompatible low-molecular-weight heparin (LMHP) was used as the gatekeepers for synergistic photothermal therapy/photodynamic therapy/chemotherapy/immunotherapy. ZnO was decomposed into cytotoxic Zn2+ ions, leading to a tumor-specific release of ICG and DOX. ZnO simultaneously produced oxygen (O2) and reactive oxygen species (ROS) for photodynamic therapy (PDT). The released ICG under laser irradiation produced ROS for PDT and raised the tumor temperature for photothermal therapy (PTT). The released DOX directly caused tumor cell death for chemotherapy. Both DOX and ICG also induced immunogenic cell death (ICD) for immunotherapy. The in vivo and in vitro results presented a superior inhibition of tumor progression, metastasis and recurrence. Therefore, this study could provide an efficient approach for designing multifunctional nanoparticles for synergistic multimodal antitumor therapy.

Exploring BODIPY derivatives as sonosensitizers for anticancer sonodynamic therapy

Sonodynamic therapy (SDT) is an emerging non-invasive and effective therapeutic modality for cancer treatment bearing benefit of deep tissue-penetration in comparison to photo-inspired therapy. However, exploring novel sonosensitizers with high sonosensitivity and desirable biosafety remains a significant challenge. Although boron dipyrromethene (BODIPY) dyes have been widely used in biomedical filed, no BODIPY-based sonosensitizers have been reported yet. Herein, we synthesized four BODIPY dyes (BDP1-BDP4) and investigated their potential applications in SDT. BDP4 exhibited superb sonosensitivity and high SDT efficiency against cancer cells and tumors in tumor-bearing mice. The types of the generated reactive oxygen species, cavitation effect, and cell apoptosis were investigated to figure out the sonodynamic therapeutic mechanisms of BDP4. This work for the first time demonstrates the potential of BODIPY dyes as novel sonosensitizers for SDT, which may pave an avenue for developing more efficient and safer sonosensitizers in future.

Near-Infrared-II-Activatable Self-Assembled Manganese Porphyrin-Gold Heterostructures for Photoacoustic Imaging-Guided Sonodynamic-Augmented Photothermal/Photodynamic Therapy

Porphyrins and their derivatives are widely used as photosensitizers and sonosensitizers in tumor treatment. Nevertheless, their poor water solubility and low chemical stability reduce their singlet oxygen (1O2) yield and, consequently, their photodynamic therapy (PDT) and sonodynamic therapy (SDT) efficiency. Although strategies for porphyrin molecule assembly have been developed to augment 1O2 generation, there is scope for further improving PDT and SDT efficiencies. Herein, we synthesized ordered manganese porphyrin (SM) nanoparticles with well-defined self-assembled metalloporphyrin networks that enabled efficient energy transfer for enhanced photocatalytic and sonocatalytic activity in 1O2 production. Subsequently, Au nanoparticles were grown in situ on the SM surface by anchoring the terminal alkynyl of porphyrin to form plasmonic SMA heterostructures, which showed the excellent near-infrared-II (NIR-II) region absorption and photothermal properties, and facilitated electron-hole pair separation and transfer. With the modification of hyaluronic acid (HA), SMAH heterostructure nanocomposites exhibited good water solubility and were actively targeted to cancer cells. Under NIR-II light and ultrasound (US) irradiation, the SMAH generates hyperthermia, and a large amount of 1O2, inducing cancer cell damage. Both in vitro and in vivo studies confirmed that the SMAH nanocomposites effectively suppressed tumor growth by decreasing GSH levels in SDT-augmented PDT/PTT. Moreover, by utilizing the strong absorption in the NIR-II window, SMAH nanocomposites can achieve NIR-II photoacoustic imaging-guided combined cancer treatment. This work provides a paradigm for enhancing the 1O2 yield of metalloporphyrins to improve the synergistic therapeutic effect of SDT/PDT/PTT.

Progress of Piezoelectric Semiconductor Nanomaterials in Sonodynamic Cancer Therapy

Sonodynamic therapy is an emerging noninvasive tumor treatment method that utilizes ultrasound to stimulate sonosensitizers to produce a large amount of reactive oxygen species, inducing tumor cell death. Though sonodynamic therapy has very promising prospects in cancer treatment, the application of early organic sonosensitizers has been limited in efficacy due to the high blood clearance-rate, poor water solubility, and low stability. Inorganic sonosensitizers have thus been developed, among which piezoelectric semiconductor materials have received increasing attention in sonodynamic therapy due to their piezoelectric properties and strong stability. In this review, we summarized the designs, principles, modification strategies, and applications of several commonly used piezoelectric materials in sonodynamic therapy and prospected the future clinical applications for piezoelectric semiconductor materials in sonodynamic therapy.

Strategies to Reverse Hypoxic Tumor Microenvironment for Enhanced Sonodynamic Therapy

Sonodynamic therapy (SDT) has emerged as a highly effective modality for the treatment of malignant tumors owing to its powerful penetration ability, noninvasiveness, site-confined irradiation, and excellent therapeutic efficacy. However, the traditional SDT, which relies on oxygen availability, often fails to generate a satisfactory level of reactive oxygen species because of the widespread issue of hypoxia in the tumor microenvironment of solid tumors. To address this challenge, various approaches are developed to alleviate hypoxia and improve the efficiency of SDT. These strategies aim to either increase oxygen supply or prevent hypoxia exacerbation, thereby enhancing the effectiveness of SDT. In view of this, the current review provides an overview of these strategies and their underlying principles, focusing on the circulation of oxygen from consumption to external supply. The detailed research examples conducted using these strategies in combination with SDT are also discussed. Additionally, this review highlights the future prospects and challenges of the hypoxia-alleviated SDT, along with the key considerations for future clinical applications. These considerations include the development of efficient oxygen delivery systems, the accurate methods for hypoxia detection, and the exploration of combination therapies to optimize SDT outcomes.

Ultrasmall iron-doped zinc oxide nanoparticles for ferroptosis assisted sono-chemodynamic cancer therapy

The efficacy and biosafety of sonodynamic therapy (SDT) are closely related to the properties of sonosensitizers. Inorganic sonosensitizers with high chemical stability and low dark toxicity are generally limited by slow metabolism and accumulation in vivo. Combined treatment strategies by inducing more redox imbalance are expected to improve the efficacy of sonodynamic antitumor therapy. Herein, we report the development of ultra-small iron-doped zinc oxide nanoparticles (FZO NPs) to achieve synergistic sono-chemodynamic therapy and low accumulation in vivo. The surface of FZO NPs with diameter of 5 nm was modified with 3-aminopropyltriethoxysilane and polyethylene glycol 600 to obtain FZO-ASP with good aqueous stability. FZO-ASP with iron doping could trigger Fenton reaction and induce ferroptosis in cancer cells. With the assistance of ultrasonic energy, FZO-ASP demonstrated enhanced inhibitory effects on proliferation of various cancer cells and murine breast tumor growth than undoped counterpart. In addition, FZO-ASP injected intravenously could be effectively excreted in vivo and showed no obvious cumulative toxicity to the treated mice. Hence, this type of ultra-small iron-doped zinc oxide nanoparticles could serve as a safe and efficient sonosensitizer agent for synergistic sono-chemodynamic cancer therapy.

2D Ultrathin Iron Doped Bismuth Oxychloride Nanosheets with Rich Oxygen Vacancies for Enhanced Sonodynamic Therapy

Sonodynamic therapy (SDT) combines ultrasound and sonosensitizers to produce toxic reactive oxygen species (ROS) for cancer cell killing. Due to the high penetration depth of ultrasound (US), SDT breaks the depth penetration barrier of conventional photodynamic therapy for the treatment of deeply seated tumors. A key point to enhance the therapeutic efficiency of SDT is the development of novel sonosensitizers with promoted ability for ROS production. Herein, ultrathin Fe-doped bismuth oxychloride nanosheets with rich oxygen vacancies and bovine serum albumin coating on surface are designed as piezoelectric sonosensitizers (BOC-Fe NSs) for enhanced SDT. The oxygen vacancies of BOC-Fe NSs provide electron trapping sites to promote the separation of e- -h+ from the band structure, which facilitates the ROS production under the ultrasonic waves. The piezoelectric BOC-Fe NSs create a built-in field and the bending bands, further accelerating the ROS generation with US irradiation. Furthermore, BOC-Fe NSs can induce ROS generation by a Fenton reaction catalyzed by Fe ion with endogenous H2 O2 in tumor tissues for chemodynamic therapy. The as-prepared BOC-Fe NSs efficiently inhibited breast cancer cell growth in both in vitro and in vivo tests. The successfully development of BOC-Fe NSs provides a new nano-sonosensitiser option for enhanced SDT for cancer therapy.

Optimized strategies of ROS-based nanodynamic therapies for tumor theranostics

Reactive oxygen species (ROS) play a crucial role in regulating the metabolism of tumor growth, metastasis, death and other biological processes. ROS-based nanodynamic therapies (NDTs) are becoming attractive due to non-invasive, low side effects and tumor-specific advantages. NDTs have rapidly developed into numerous branches, such as photodynamic therapy, chemodynamic therapy, sonodynamic therapy and so on. However, the complexity of the tumor microenvironment and the limitations of existing sensitizers have greatly restricted the therapeutic effects of NDTs, which heavily rely on ROS levels. To address the limitations of NDTs, various strategies have been developed to increase ROS yield, which is an urgent aspect for the positive development of NDTs. In this review, the nanodynamic potentiation strategies in terms of unique properties and universalities of NDTs are comprehensively outlined. We mainly summarize the current dilemmas faced by each NDT and the respective solutions. Meanwhile, the NDTs universalities-based potentiation strategies and NDTs-based combined treatments are elaborated. Finally, we conclude with a discussion of the key issues and challenges faced in the development and clinical transformation of NDTs.

Nanomaterials-based precision sonodynamic therapy enhancing immune checkpoint blockade: A promising strategy targeting solid tumor

Burgeoning is an evolution from conventional photodynamic therapy (PDT). Thus, sonodynamic therapy (SDT) regulated by nanoparticles (NPs) possesses multiple advantages, including stronger penetration ability, better biological safety, and not reactive oxygen species (ROS)-dependent tumor-killing effect. However, the limitation to tumor inhibition instead of shrinkage and the incapability of eliminating metastatic tumors hinder the clinical potential for SDT. Fortunately, immune checkpoint blockade (ICB) can revive immunological function and induce a long-term immune memory against tumor rechallenges. Hence, synergizing NPs-based SDT with ICB can provide a promising therapeutic outcome for solid tumors. Herein, we briefly reviewed the progress in NPs-based SDT and ICB therapy. We highlighted the synergistic anti-tumor mechanisms and summarized the representative preclinical trials on SDT-assisted immunotherapy. Compared to other reviews, we provided comprehensive and unique perspectives on the innovative sonosensitizers in each trial. Moreover, we also discussed the current challenges and future corresponding solutions.

Defect-rich platinum-zinc oxide heterojunction as a potent ROS amplifier for synergistic sono-catalytic therapy

Sonodynamic therapy (SDT) is a physical therapy that utilizes critical sonosensitizers triggered by ultrasound to achieve an effective non-invasive tumor treatment. However, the inadequate sonodynamic efficacy and low responsive activities of traditional inorganic sonosensitizers have hindered its practical application. Here, we rationally design a platinum-zinc oxide (PtZnO) sonosensitizer to significantly enhance the efficacy of SDT through its inherent bandgap structure and dual-nanozyme activities. The PtZnO possesses a narrow bandgap (2.89 eV) and an appropriate amount of oxygen defects, which promote the efficiency of electrons and holes separation and the generation of reactive oxygen species (ROS) under US irradiation. Simultaneously, the PtZnO exhibits both catalase-like and peroxidase-like activities, which effectively catalyze endogenous H2O2 into a large number of O2 and toxic hydroxyl radicals (•OH), thus achieving an efficient enhancement of SDT and catalytic therapy. Moreover, the PtZnO has significant glutathione consumption performance, further amplifying the oxidative stress. Ultimately, the PtZnO achieves a triple ROS amplification effect, with the yields of singlet oxygen (1O2) and •OH reaching 859.1 % and 614.4 %, respectively, inducing a highly effective sono-catalytic therapy with a remarkable tumor inhibition rate of 98.1 %. This study expands the application of ZnO semiconductor heterojunctions in the nanomedicine area, and the simple yet efficient design of the PtZnO provides a strategy for the development of sonosensitizers. STATEMENT OF SIGNIFICANCE: A platinum-zinc oxide (PtZnO) heterojunction sonosensitizer is constructed with dual-nanozyme activities and achieves a triple ROS amplification effect, leading to an efficient synergistic sono-catalytic therapy. The PtZnO owns an inherent narrow bandgap and abundant oxygen defects, thus exhibiting an efficient sonosensitizer performance. It also possesses both catalase-like and peroxidase-like activities, which effectively catalyze the endogenous H2O2 into a large quantity of O2 and toxic hydroxyl radicals, thereby enhancing the SDT and catalytic therapy. Furthermore, its prominent glutathione consumption performance further amplifies oxidative stress. The yields of singlet oxygen and hydroxyl radicals reach up to 859.1 % and 614.4 %, respectively, inducing a highly effective sono-catalytic therapy with an impressive tumor inhibition rate of 98.1 %.

A pH-responsive ZC-QPP hydrogel for synergistic antibacterial and antioxidant treatment to enhance wound healing

The problems of bacterial resistance and high oxidation level severely limit wound healing. Therefore, we constructed a multifunctional platform of chitosan quaternary ammonium salts (QCS)/polyvinyl alcohol (PVA)/polyethylene glycol (PEG) hydrogels (QPP) loaded with ZnO@CeO2 (ZC-QPP). Firstly, the hydrogel was co-cross-linked by hydrogen and borate ester bonds, which allows easy adherence to a tissue surface for offering a protective barrier and moist environment for wounds. The chitosan quaternary ammonium salts due to their amino groups have inherent antibacterial properties to induce bacterial death. In response to the acidic conditions of the bacterial infection microenvironment, the borate ester bonds in the QPP hydrogel break and the ZC NCs dispersed in the hydrogel are released. The gradual dissociation of Zn2+ under acidic conditions can directly damage bacterial membranes. The wound site of bacterial infection always causes overexpression of reactive oxygen species (ROS) levels, often leading to inflammation and preventing rapid wound repair. CeO2 can eliminate excess ROS to reduce the inflammatory response. From in vitro and in vivo results, the high biosafety of the ZC-QPP hydrogel has demonstrated excellent antibacterial and antioxidant performance to enhance wound healing. Therefore, the ZC-QPP hydrogel opens a method to develop multifunctional synergistic therapeutic platforms combining enzyme-like nanomaterials with hydrogels for synergistic antibacterial and antioxidant treatment to promote wound healing.

Oxygen-Deficient Bioceramics: Combination of Diagnosis, Therapy, and Regeneration

The journey of ceramics in medicine has been synchronized with an evolution from the first generation-alumina, zirconia, etc.-to the third -3D scaffolds. There is an up-and-coming member called oxygen-deficient or colored bioceramics, which have recently found their way through biomedical applications. The oxygen vacancy steers the light absorption toward visible and near infrared regions, making the colored bioceramics multifunctional-therapeutic, diagnostic, and regenerative. Oxygen-deficient bioceramics are capable of turning light into heat and reactive oxygen species for photothermal and photodynamic therapies, respectively, and concomitantly yield infrared and photoacoustic images. Different types of oxygen-deficient bioceramics have been recently developed through various synthesis routes. Some of them like TiO2- x , MoO3- x , and WOx have been more investigated for biomedical applications, whereas the rest have yet to be scrutinized. The most prominent advantage of these bioceramics over the other biomaterials is their multifunctionality endowed with a change in the microstructure. There are some challenges ahead of this category discussed at the end of the present review. By shedding light on this recently born bioceramics subcategory, it is believed that the field will undergo a big step further as these platforms are naturally multifunctional.

Inorganic Sonosensitizers for Sonodynamic Therapy in Cancer Treatment

The rapid development of nanomedicine and nanobiotechnology has allowed the emergence of various therapeutic modalities with excellent therapeutic efficiency and biosafety, among which, the sonodynamic therapy (SDT), a combination of low-intensity ultrasound and sonosensitizers, is emerging as a promising noninvasive treatment modality for cancer treatment due to its deeper penetration, good patient compliance, and minimal damage to normal tissue. The sonosensitizers are indispensable components in the SDT process because their structure and physicochemical properties are decisive for therapeutic efficacy. Compared to the conventional and mostly studied organic sonosensitizers, inorganic sonosensitizers (noble metal-based, transition metal-based, carbon-based, and silicon-based sonosensitizers) display excellent stability, controllable morphology, and multifunctionality, which greatly expand their application in SDT. In this review, the possible mechanisms of SDT including the cavitation effect and reactive oxygen species generation are briefly discussed. Then, the recent advances in inorganic sonosensitizers are systematically summarized and their formulations and antitumor effects, particularly highlighting the strategies for optimizing the therapeutic efficiency, are outlined. The challenges and future perspectives for developing state-of-the-art sonosensitizers are also discussed. It is expected that this review will shed some light on future screening of decent inorganic sonosensitizers for SDT.

Oxygen-defective zinc oxide nanoparticles as highly efficient and safe sonosensitizers for cancer therapy

Herein, an oxygen defect-modulated zinc oxide sonosensitizer is designed, which enhances the absorbance of ultrasound energy and suppresses the recombination of ultrasound-initiated electrons and holes to promote reactive oxygen species yield. It achieves a high tumor inhibition efficiency of 79.9%, which exhibits a potential application for sonodynamic cancer therapy.

Recent Developments of Inorganic Nanosensitizers for Sonodynamic Therapy

As a noninvasive treatment, sonodynamic therapy (SDT) has been widely used in the treatment of tumors because of its ability to penetrate deep tissue with few side effects. As the key factor of SDT, it is meaningful to design and synthesize efficient sonosensitizers. Compared with organic sonosensitizers, inorganic sonosensitizers can be easily excited by ultrasound. In addition, inorganic sonosensitizers with stable properties, good dispersion, and long blood circulation time, have great development potential in SDT. This review summarizes possible mechanisms of SDT (sonoexcitation and ultrasonic cavitation) in detail. Based on these mechanisms, the design and synthesis of inorganic nanosonosensitizers can be divided into three categories: traditional inorganic semiconductor sonosensitizers, enhanced inorganic semiconductor sonosensitizers, and cavitation-enhanced sonosensitizers. Subsequently, the current efficient construction methods of sonosensitizers are summarized including accelerated semiconductor charge separation and enhanced production of reactive oxygen species through ultrasonic cavitation. Furthermore, the advantages and disadvantages of different inorganic sonosensitizers and detailed strategies are systematically discussed on how to enhance SDT. Hopefully, this review could provide new insights into the design and synthesis of efficient inorganic nano-sonosensitizers for SDT.

Stimuli responsive nanosonosensitizers for sonodynamic therapy

Sonodynamic therapy (SDT) has gained significant attention in the treatment of deep tumors and multidrug-resistant (MDR) bacterial infections due to its high tissue penetration depth, high spatiotemporal selectivity, and noninvasive therapeutic method. SDT combines low-intensity ultrasound (US) and sonosensitizers to produce lethal reactive oxygen species (ROS) and external damage, which is the main mechanism behind this therapy. However, traditional organic small-molecule sonosensitizers display poor water solubility, strong phototoxicity, and insufficient targeting ability. Inorganic sonosensitizers, on the other hand, have low ROS yield and poor biocompatibility. These drawbacks have hindered SDT's clinical transformation and application. Hence, designing stimuli-responsive nano-sonosensitizers that make use of the lesion's local microenvironment characteristics and US stimulation is an excellent alternative for achieving efficient, specific, and safe treatment. In this review, we provide a comprehensive overview of the currently accepted mechanisms in SDT and discuss the application of responsive nano-sonosensitizers in the treatment of tumor and bacterial infections. Additionally, we emphasize the significance of the principle and process of response, based on the classification of response patterns. Finally, this review emphasizes the potential limitations and future perspectives of SDT that need to be addressed to promote its clinical transformation.

Defect Engineering in Biomedical Sciences

With the promotion of nanochemistry research, large numbers of nanomaterials have been applied in vivo to produce desirable cytotoxic substances in response to endogenous or exogenous stimuli for achieving disease-specific therapy. However, the performance of nanomaterials is a critical issue that is difficult to improve and optimize under biological conditions. Defect-engineered nanoparticles have become the most researched hot materials in biomedical applications recently due to their excellent physicochemical properties, such as optical properties and redox reaction capabilities. Importantly, the properties of nanomaterials can be easily adjusted by regulating the type and concentration of defects in the nanoparticles without requiring other complex designs. Therefore, this tutorial review focuses on biomedical defect engineering and briefly discusses defect classification, introduction strategies, and characterization techniques. Several representative defective nanomaterials are especially discussed in order to reveal the relationship between defects and properties. A series of disease treatment strategies based on defective engineered nanomaterials are summarized. By summarizing the design and application of defective engineered nanomaterials, a simple but effective methodology is provided for researchers to design and improve the therapeutic effects of nanomaterial-based therapeutic platforms from a materials science perspective.

2D Piezoelectric BiVO4 Artificial Nanozyme with Adjustable Vanadium Vacancy for Ultrasound Enhanced Piezoelectric/Sonodynamic Therapy

Increasing the yield of reactive oxygen species (ROS) to enhance oxidative stress in cells is an eternal goal in cancer therapy. In this study, BiVO4 artificial nanozyme is developed with adjustable vanadium vacancy for ultrasound (US) enhanced piezoelectric/sonodynamic therapy. Under US excitation, the vanadium vacancy-rich BiVO4 nanosheets (abbreviated Vv -r BiVO4 NSs) facilitate the generation of a large number of electrons to improve the ROS yield. Meanwhile, the mechanical strain imposed by US irradiation makes the Vv -r BiVO4 NSs display a typical piezoelectric response, which tilts the conduction band to be more negative and the valance band more positive than the redox potentials of O2 /O2 •- and H2 O/·OH, boosting the efficiency of ROS generation. Both density functional theory calculations and experiments confirm that the introduction of cationic vacancy can improve the sonodynamic effect. As expected, Vv -r BiVO4 NSs have better peroxidase enzyme catalytic and glutathione depletion activities, resulting in increased intracellular oxidative stress. This triple amplification strategy of oxidative stress induced by US substantially inhibits the growth of cancer cells. The work may open an avenue to achieve a synergetic therapy by introducing cationic vacancy, broadening the biomedical use of piezoelectric materials.

Single Atom Iron-Doped Graphic-Phase C3 N4 Semiconductor Nanosheets for Augmented Sonodynamic Melanoma Therapy Synergy with Endowed Chemodynamic Effect

Sonodynamic therapy (SDT) is a non-invasive therapeutic modality with high tissue-penetration depth to induce reactive oxygen species (ROS) generation for tumor treatment. However, the clinical translation of SDT is restricted seriously by the lack of high-performance sonosensitizers. Herein, the distinct single atom iron (Fe)-doped graphitic-phase carbon nitride (C3 N4 ) semiconductor nanosheets (Fe-C3 N4 NSs) are designed and engineered as chemoreactive sonosensitizers to effectively separate the electrons (e- ) and holes (h+ ) pairs, achieving high yields of ROS generation against melanoma upon ultrasound (US) activation. Especially, the single atom Fe doping not only substantially elevates the separation efficiency of the e- -h+ pairs involved in SDT, but also can serve as high-performance peroxidase mimetic enzyme to catalyze the Fenton reaction for generating abundant hydroxyl radicals, therefore synergistically augmenting the curative effect mediated by SDT. As verified by density functional theory simulation, the doping of Fe atom significantly promotes the charge redistribution in the C3 N4 -based NSs, which improves their synergistic SDT/chemodynamic activities. Both the in vitro and in vivo assays demonstrate that Fe-C3 N4 NSs feature an outstanding antitumor effect by aggrandizing the sono-chemodynamic effect. This work illustrates a unique single-atom doping strategy for ameliorating the sonosensitizers, and also effectively expands the innovative anticancer-therapeutic applications of semiconductor-based inorganic sonosensitizers.

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.

Enhanced Sonodynamic Cancer Therapy through Iron-Doping and Oxygen-Vacancy Engineering of Piezoelectric Bismuth Tungstate Nanosheets

Sonodynamic therapy (SDT) is regarded as a new-rising strategy for cancer treatment with low invasiveness and high tissue penetration, but the scarcity of high-efficiency sonosensitizers has seriously hindered its application. Herein, the iron-doped and oxygen-deficient bismuth tungstate nanosheets (BWO-Fe NSs) with piezotronic effect are synthesized for enhanced SDT. Due to the existence of oxygen defects introduced through Fe doping, the bandgap of BWO-Fe is significantly narrowed so that BWO-Fe can be more easily activated by exogenous ultrasound (US). The oxygen defects acting as the electron traps inhibit the recombination of US-induced electrons and holes. More importantly, the dynamically renewed piezoelectric potential facilitates the migration of electrons and holes to opposite side and causes energy band bending, which further promotes the production of reactive oxygen species. Furthermore, Fe doping endows BWO-Fe with Fenton reactivity, which converts hydrogen peroxide (H₂ O₂ ) in tumor microenvironment into hydroxyl radicals (•OH), thereby amplifying the cellular oxidative damage and enhancing SDT. Both in vitro and in vivo experiments illustrate their high cytotoxicity and tumor suppression rate against refractory breast cancer in mice. This work may provide an alternative strategy to develop oxygen-deficient piezoelectric sonosensitizers for enhanced SDT via doping metal ions.

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.

The fundamentals and applications of piezoelectric materials for tumor therapy: recent advances and outlook

Malignant tumors are one of the main diseases leading to death, and the vigorous development of nanotechnology has opened up new frontiers for antitumor therapy. Currently, researchers are focused on solving the biomedical challenges associated with traditional anti-tumor medical methods, promoting the research and development of nano-drug carriers and new nano-drugs, which brings great hope for improving the curative effect and reducing toxic and side effects. Among the new systems being investigated, piezoelectric nano biomaterials, including ferroelectrics, piezoelectric and pyroelectric materials, have recently received extensive attention for antitumor applications. By coupling force, light, magnetism or heat and electricity, polarized charges are generated in these materials microscopically, forming a piezo-potential and establishing a built-in electric field. Polarized charges can directly act on the materials in the tumor micro-environment and also assist in the separation of carriers and inhibit recombination based on piezoelectric theory and piezoelectric optoelectronic theory. Based on this, piezoelectric materials convert various forms of primary energy (such as light energy, mechanical energy, thermal energy and magnetic energy) from the surrounding environment into secondary energy (such as electrical energy and chemical energy). Herein, we review the basic theory and principles of piezoelectric materials, pyroelectric materials and ferroelectric materials as nanomedicine. Then, we summarize the types of piezoelectric materials reported to date and their wide applications in treatment, imaging, device construction and probe detection in various tumor treatment fields. Based on this, we discuss the relevant characteristics and post-processing strategies of nano piezoelectric biomaterials to obtain the maximum piezoelectric response. Finally, we present the key challenges and future prospects for the development of ferroelectric, piezoelectric and pyroelectric nanomaterial-based nanoagents for efficient energy harvesting and conversion for desirable therapeutic outcomes.

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.

Perovskite-Type Manganese Vanadate Sonosensitizers with Biodegradability for Enhanced Sonodynamic Therapy of Cancer

Sonodynamic therapy (SDT) has attracted intensive attention, but is still hindered by low sonosensitization and non-biodegradability of the traditional sonosensitizers. Herein, perovskite-type manganese vanadate (MnVO₃ ) sonosensitizers integrating high reactive oxide species (ROS) production efficiency and appropriate bio-degradability are developed for enhanced SDT. Taking advantage of the intrinsic properties of perovskites such as narrow bandgap and substantial oxygen vacancies, MnVO₃ shows a facile ultrasound (US)-triggered electrons-holes separation and restrained recombination, thus enhancing the ROS quantum yield in SDT. Furthermore, MnVO₃ exhibits a considerable chemodynamic therapy (CDT) effect under the acidic condition probably owing to the presence of manganese and vanadium ions. Due to the presence of high-valent vanadium, MnVO₃ can also eliminate glutathione (GSH) within the tumor microenvironment, which synergistically amplifies the efficacy of SDT and CDT. Importantly, the perovskite structure bestows MnVO₃ with superior biodegradability, which alleviates the long-term presence of residues in metabolic organs after therapeutic actions. Based on these characteristics, US-assisted MnVO₃ achieves an excellent antitumor outcome along with low systemic toxicity. Overall, perovskite-type MnVO₃ may be promising sonosensitizers for highly efficient and safe treatment of cancer. The work attempts to explore the potential utility of perovskites in the design of degradable sonosensitizers.

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.

Ultrasound-triggered interfacial engineering-based microneedle for bacterial infection acne treatment

Acne is an inflammatory skin disease mainly caused by Propionibacterium acnes, which can cause local inflammatory reactions and develop into chronic inflammatory diseases in severe cases. To avoid the use of antibiotics and to effectively treat the site of acne, we report a sodium hyaluronate microneedle patch that mediates the transdermal delivery of ultrasound-responsive nanoparticles for the effective treatment of acne. The patch contains nanoparticles formed by zinc porphyrin-based metal-organic framework and zinc oxide (ZnTCPP@ZnO). We demonstrated activated oxygen-mediated killing of P. acnes with an antibacterial efficiency of 99.73% under 15 min of ultrasound irradiation, resulting in a decrease in levels of acne-related factors, including tumor necrosis factor-α, interleukins, and matrix metalloproteinases. The zinc ions up-regulated DNA replication-related genes, promoting the proliferation of fibroblasts and, consequently, skin repair. This research leads to a highly effective strategy for acne treatment through the interface engineering of ultrasound response.

Navigating zinc-involved nanomedicine in oncotherapy

Zinc (Zn), extolled as "the flower of life" in modern medicine, has been extensively highlighted with its physiological functions to maintain growth, development, and metabolism homeostasis. Driven by the substantial advancement of nanotechnology and oncology, Zn-involved nanomedicines integrating the intrinsic bioactivity of Zn species and the physiochemical attributes of Zn-composed nanosystems have blazed a highly efficient and relatively biosafe antineoplastic path. In this review, we aim to highlight and discuss the recent representative modalities of emerging Zn-involved oncology nanomedicine, mainly emphasizing the rational design, biological effect and biosafety, and therapeutic strategies. In addition, we provide the underlying critical obstacles and future perspectives of Zn-involved oncology nanomedicines, primarily focusing on the chances and challenges of clinical translation. Furthermore, we hope the review can give rise to opportunities within oncology nanomedicine and other biomedical fields, promoting the prosperity and progress of the "Zincic Age".

Reactive oxygen species-upregulating nanomedicines towards enhanced cancer therapy

Reactive oxygen species (ROS) play a crucial role in physiological and pathological processes, emerging as a therapeutic target in cancer. Owing to the high concentration of ROS in solid tumor tissues, ROS-based treatments, such as photodynamic therapy and chemodynamic therapy, and ROS-responsive drug delivery systems have been widely explored to powerfully and specifically suppress tumors. However, their anticancer efficacy is still hampered by the heterogeneous ROS levels, and thus comprehensively upregulating the ROS levels in tumor tissues can ensure an enhanced therapeutic effect, which can further sensitize and/or synergize with other therapies to inhibit tumor growth and metastasis. Herein, we review the recently emerging drug delivery strategies and technologies for increasing the H₂O₂, ˙OH, ¹O₂, and ˙O₂^- concentrations in cancer cells, including the efficient delivery of natural enzymes, nanozymes, small molecular biological molecules, and nanoscale Fenton-reagents and semiconductors and neutralization of intracellular antioxidant substances and localized input of mechanical and electromagnetic waves (such as ultrasound, near infrared light, microwaves, and X-rays). The applications of these ROS-upregulating nanosystems in enhancing and synergizing cancer therapies including chemotherapy, chemodynamic therapy, phototherapy, and immunotherapy are surveyed. In addition, we discuss the challenges of ROS-upregulating systems and the prospects for future studies.

An Ultrasound-Triggered Nanoplatform for Synergistic Sonodynamic-Nitric Oxide Therapy

Ultrasound (US)-triggered sonodynamic therapy (SDT) has aroused intensive interest as a powerful alternative for cancer treatment in recent years due to its non-invasiveness and deep tissue penetration. However, the therapeutic effect of SDT alone is still limited by intrinsic hypoxia in solid tumors. Combined synergistic therapy strategies are highly desired for improving therapeutic efficiency. Herein, a rationally designed intelligent theranostic nanoplatform is developed for the enhancement of cancer treatment through synergistic SDT and nitric oxide (NO) therapy. This US-triggered nanoplatform is fabricated by integrating a sonosensitizer Rose Bengal (RB) and a NO donor (SNO) into manganese-doped hollow mesoporous silica nanoparticles (MH-SNO@RB). Impressively, the acidic and reducing tumor microenvironment accelerates the sustainable release of Mn ions from the framework, which facilitates the MH-SNO@RB to be used as a contrast agent for magnetic resonance imaging. More importantly, the reactive oxygen species (ROS) generated by RB and NO molecules released from SNO, which are simultaneously triggered by US, can react with each other to yield highly reactive peroxynitrite (ONOO^-) ions for effective tumor inhibition both in vitro and in vivo. Furthermore, the nanoplatform demonstrates good hemocompatibility and histocompatibility. This study opens a new strategy for the full utilization of US and intelligent design avenues for high-performance cancer treatment.

Hollow CoP@N-Carbon Nanospheres: Heterostructure and Glucose-Enhanced Charge Separation for Sonodynamic/Starvation Therapy

Sonodynamic therapy (SDT) can be described as ultrasonic (US) catalysis. Adequate charge separation is considered as effective means to promote reactive oxygen species (ROS). Here, hollow CoP@N-carbon@PEG (CPCs@PEG) nanospheres (∼60 nm) are prepared as sonosensitizers, showing greater ROS generation than pure CoP@PEG under US irradiation. Both ¹O₂ and ·O₂^- are activation species that are determined by O₂ and electrons. The great SDT performance of CPCs@PEG is ascribed to the heterostructure which promotes the separation and transfer for US-generated electrons and holes. In addition, holes can be further captured by endogenous glucose that is in favor of electron aggregation and ROS generation. Moreover, the consumption of glucose would decrease intracellular ATP for starvation therapy. Given the higher oxidation ability of Co³⁺, CPCs@PEG nanospheres possess catalase (CAT) activity to convert H₂O₂ into O₂ for assisting ROS generation. Moreover, they also can oxidize glutathione (GSH) as a mimic GSH oxidase to break intratumor redox balance, facilitating oxidative stress. More importantly, the nanocomposites reveal good degradation ability dominated by the oxidation from insoluble phosphide into soluble phosphate, accelerating elimination via urine and feces within 14 days. CPCs@PEG nanospheres integrate the above effects not only to reveal great tumor inhibition ability but also to excite immune activation for anticancer.