Two-Dimensional FePS3 Nanosheets as an Integrative Sonosensitizer/Nanocatalyst for Efficient Nanodynamic Tumor Therapy

Engineering Sonosensitizer-Derived Nanotheranostics for Augmented Sonodynamic Therapy

Sonodynamic therapy (SDT), featuring noninvasive, deeper penetration, low cost, and repeatability, is a promising therapy approach for deep-seated tumors. However, the general or only utilization of SDT shows low efficiency and unsatisfactory treatment outcomes due to the complicated tumor microenvironment (TME) and SDT process. To circumvent the issues, three feasible approaches for enhancing SDT-based therapeutic effects, including sonosensitizer optimization, strategies for conquering hypoxia TME, and combinational therapy are summarized, with a particular focus on the combination therapy of SDT with other therapy modalities, including chemodynamic therapy, photodynamic therapy, photothermal therapy, chemotherapy, starvation therapy, gas therapy, and immunotherapy. In the end, the current challenges in SDT-based therapy on tumors are discussed and feasible approaches for enhanced therapeutic effects are provided. It is envisioned that this review will provide new insight into the strategic design of high-efficiency sonosensitizer-derived nanotheranostics, thereby augmenting SDT and accelerating the potential clinical transformation.

Metal-Organic Framework Nanomaterials as a Medicine for Catalytic Tumor Therapy: Recent Advances

Nanomaterials, with unique physical, chemical, and biocompatible properties, have attracted significant attention as an emerging active platform in cancer diagnosis and treatment. Amongst them, metal-organic framework (MOF) nanostructures are particularly promising as a nanomedicine due to their exceptional surface functionalities, adsorption properties, and organo-inorganic hybrid characteristics. Furthermore, when bioactive substances are integrated into the structure of MOFs, these materials can be used as anti-tumor agents with superior performance compared to traditional nanomaterials. In this review, we highlight the most recent advances in MOFs-based materials for tumor therapy, including their application in cancer treatment and the underlying mechanisms.

Ionized water-soluble organic nanosheets with light/ultrasound dual excitation channels for efficient killing of multidrug-resistant bacteria

A novel ionized heavy-atom-free two-dimensional organic nanosheet was prepared and exhibited highly selective generation of singlet oxygen under both light and ultrasound excitation. These ionized nanosheets displayed excellent dispersibility in water and enhanced singlet oxygen production efficiency compared to their non-assembled monomers. Antimicrobial experiments have revealed their potent bactericidal effects on drug-resistant E. coli and S. aureus under both visible light and ultrasound irradiation.

Advancing piezoelectric 2D nanomaterials for applications in drug delivery systems and therapeutic approaches

Precision drug delivery and multimodal synergistic therapy are crucial in treating diverse ailments, such as cancer, tissue damage, and degenerative diseases. Electrodes that emit electric pulses have proven effective in enhancing molecule release and permeability in drug delivery systems. Moreover, the physiological electrical microenvironment plays a vital role in regulating biological functions and triggering action potentials in neural and muscular tissues. Due to their unique noncentrosymmetric structures, many 2D materials exhibit outstanding piezoelectric performance, generating positive and negative charges under mechanical forces. This ability facilitates precise drug targeting and ensures high stimulus responsiveness, thereby controlling cellular destinies. Additionally, the abundant active sites within piezoelectric 2D materials facilitate efficient catalysis through piezochemical coupling, offering multimodal synergistic therapeutic strategies. However, the full potential of piezoelectric 2D nanomaterials in drug delivery system design remains underexplored due to research gaps. In this context, the current applications of piezoelectric 2D materials in disease management are summarized in this review, and the development of drug delivery systems influenced by these materials is forecast.

Catechol-Isolated Atomically Dispersed Nanocatalysts for Self-Motivated Cocatalytic Tumor Therapy

Nanocatalytic tumor therapy based on Fenton nanocatalysts has attracted considerable attention because of its therapeutic specificity, enhanced outcomes, and high biocompatibility. Nevertheless, the rate-determining step in Fenton chemistry, which involves the transition of a high-valence metallic center (FeIII ) to a Fenton-active low-valence metallic center (FeII ), has hindered advances in nanocatalyst-based therapeutics. In this study, we constructed mesoporous single iron atomic nanocatalysts (mSAFe NCs) by employing catechols from dopamine to coordinate and isolate single iron atoms. The catechols also serve as reductive ligands, generating a field-effect-based cocatalytic system that instantly reduces FeIII species to FeII species within the mSAFe NCs. This self-motivated cocatalytic strategy enabled by mSAFe NCs accelerates the kinetics of the Fenton catalytic reaction, resulting in remarkable performance for nanocatalytic tumor therapy both in vitro and in vivo.

Interfacial engineering of Ti3C2-TiO2 MXenes by managing surface oxidation behavior for enhanced sonodynamic therapy

As a kind of reactive oxygen species (ROS) mediated therapy, sonodynamic therapy (SDT) has attracted great interest in cancer therapy. However, highly efficient and biocompatible sonosensitizers are urgently required to improve the therapeutic efficiency of SDT. In this work, Ti3C2-TiO2 MXenes were controllably synthesized as good sonosensitizers through interface engineering by regulating the dissolved oxygen concentration of the aqueous solution. The as-prepared Ar-Ti3C2-TiO2 MXene possessed a narrow band gap of 2.37 eV with promoted charge carrier transformation and efficient electron-hole separation. Compared with pure TiO2 sonosensitizers, the Ar-Ti3C2-TiO2 MXene displayed higher US-triggered reactive oxygen species (ROS) generation efficiency. In addition, the structurally maintained Ar-Ti3C2-TiO2 possessed good photothermal conversion efficiency and the laser irradiation could greatly improve the electron-hole pair separation efficiency to further increase the ROS generation capability. After modification with arginyl-glycyl-aspartic (RGD) peptide, the Ar-Ti3C2-TiO2-RGD could efficiently accumulate in the tumor sites and achieve effective PTT enhanced SDT to eliminate tumors after intravenous injection without causing appreciable long-term toxicity. Therefore, this work presented a new way to construct safe sonosensitizers for enhanced SDT and the as-prepared Ar-Ti3C2-TiO2-RGD displayed good potential for further clinical translation. STATEMENT OF SIGNIFICANCE: To achieve superior tumor treatment, the nanosized TiO2/Ti3C2 heterostructure was controllably synthesized through interface engineering by regulating the dissolved oxygen concentration of the aqueous solution using inert gas. The oxidation-optimized Ar-Ti3C2-TiO2 MXene possessed good sonodynamic performance with a narrow band gap of 2.37 eV and good photothermal conversion efficiency of 47.3% with structurally maintained Ti3C2 MXene. Additionally, the laser irradiation could greatly improve the electron-hole pair separation efficiency to further boost sonodynamic performance of Ar-Ti3C2-TiO2 MXene. Encouragingly, the Ar-Ti3C2-TiO2-RGD could efficiently accumulate in the tumor sites and achieve effective PTT enhanced SDT to eliminate tumors.

Recent Advances of Emerging Metal-Containing Two-Dimensional Nanomaterials in Tumor Theranostics

In recent years, metal-containing two-dimensional (2D) nanomaterials, among various 2D nanomaterials have attracted widespread attention because of their unique physical and chemical properties, especially in the fields of biomedical applications. Firstly, the review provides a brief introduction to two types of metal-containing 2D nanomaterials, based on whether metal species take up the major skeleton of the 2D nanomaterials. After this, the synthetical approaches are summarized, focusing on two strategies similar to other 2D nanomaterials, top-down and bottom-up methods. Then, the performance and evaluation of these 2D nanomaterials when applied to cancer therapy are discussed in detail. The specificity of metal-containing 2D nanomaterials in physics and optics makes them capable of killing cancer cells in a variety of ways, such as photodynamic therapy, photothermal therapy, sonodynamic therapy, chemodynamic therapy and so on. Besides, the integrated platform of diagnosis and treatment and the clinical translatability through metal-containing 2D nanomaterials is also introduced in this review. In the summary and perspective section, advanced rational design, challenges and promising clinical contributions to cancer therapy of these emerging metal-containing 2D nanomaterials are discussed.

Sonocatalytic cancer therapy: theories, advanced catalysts and system design

Treating cancer remains one of the most formidable challenges in modern medicine, with traditional treatment options often being limited by poor therapeutic outcomes and unacceptable side effects. Nanocatalytic therapy activates tumor-localized catalytic reactions in situ via nontoxic or minimally toxic nanocatalysts responding to unique cues from the tumor microenvironment or external stimuli. In particular, sonocatalytic cancer therapy is a promising approach that has emerged as a potential solution to this problem through the combination of ultrasound waves and catalytic materials to selectively target and destroy cancer cells. Compared to light, ultrasound exhibits higher spatial precision, lower energy attenuation, and superior tissue penetrability, furnishing more energy to catalysts. Multidimensional modulation of nanocatalyst structures and properties is pivotal to maximizing catalytic efficiency given constraints in external stimulative energy as well as substrate types and levels. In this review, we discuss the various theories and mechanisms underlying sonocatalytic cancer therapy, as well as advanced catalysts that have been developed for this application. Additionally, we explore the design of sonocatalytic cancer therapy systems, including the use of heterojunction catalysts and the optimal conditions for achieving maximum therapeutic effects. Finally, we highlight the potential benefits of sonocatalytic cancer therapy over traditional cancer treatments, including its noninvasive nature and lower toxicity.

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.

Improvement of the effectiveness of sonodynamic therapy: by optimizing components and combination with other treatments

Sonodynamic therapy (SDT) is an emerging treatment method. In comparison with photodynamic therapy (PDT), SDT exhibits deep penetration, high cell membrane permeability, and free exposure to light capacity. Unfortunately, owing to inappropriate ultrasound parameter selection, poor targeting of sonosensitizers, and the complex tumor environment, SDT is frequently ineffective. In this review, we describe the approaches for selecting ultrasound parameters and how to develop sonosensitizers to increase targeting and improve adverse tumor microenvironments. Furthermore, the potential of combining SDT with other treatment methods, such as chemotherapy, chemodynamic therapy, photodynamic therapy, photothermal therapy, and immunotherapy, is discussed to further increase the treatment efficiency of SDT.

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 %.

Tumor microenvironment-mediated NIR-I-to-NIR-II transformation of Au self-assembly for theranostics

The misdiagnosis of tumors due to insufficient penetration depth or signal interference and damage to normal tissues due to indiscriminate treatment are the biggest challenges in using photothermal agents for clinical translation. To overcome these limitations, a strategy of switching from the near-infrared (NIR)-I region to the NIR-II region was developed based on tumor microenvironment (TME)-mediated gold (Au) self-assembly. Using zeolitic imidazolate framework-8 (ZIF-8) metal-organic framework-coated gold nanorods (AuNRs@ZIF-8) as a model photothermal agent, we demonstrated that only a NIR-I photoacoustic imaging signal was observed in normal tissue because ZIF-8 could prevent the aggregation of AuNRs. However, when ZIF-8 dissociated in the TME, the AuNRs aggregated to activate NIR-II photoacoustic imaging and attenuate the NIR-I signal, thereby allowing an accurate diagnosis of tumors based on signal transformation. Notably, TME-activated NIR-II photothermal therapy could also inhibit tumor growth. Therefore, this TME-activated NIR-I-to-NIR-II switching strategy could improve the accuracy of deep-tumor diagnoses and avoid the injury caused by undifferentiated treatment. STATEMENT OF SIGNIFICANCE: Photothermal agents used for photoacoustic imaging and photothermal therapy have garnered great attention for tumor theranostics. However, always "turned on" near-infrared (NIR)-I laser (700-1000 nm)-responsive photothermal agents face issues of penetration depth and damage to normal tissues. In contrast, tumor microenvironment-activated NIR-II "smart" photothermal agents exhibit deeper penetration depth and tumor selectivity. Therefore, a NIR-I-to-NIR-II switching strategy was developed based on tumor microenvironment-mediated Au self-assembly. This work provides a new strategy for developing tumor microenvironment-activated NIR-II smart photothermal agents.