Recent advances of sonodynamic therapy in cancer treatment

Recent advances of ultrasound-responsive nanosystems in tumor immunotherapy

Immunotherapy has revolutionized cancer treatment by boosting the immune system and preventing disease escape mechanisms. Despite its potential, challenges like limited response rates and adverse immune effects impede its widespread clinical adoption. Ultrasound (US), known for its safety and effectiveness in tumor diagnosis and therapy, has been shown to significantly enhance immunotherapy when used with nanosystems. High-intensity focused ultrasound (HIFU) can obliterate tumor cells and elicit immune reactions through the creation of immunogenic debris. Low-intensity focused ultrasound (LIFU) bolsters tumor immunosuppression and mitigates metastasis risk by concentrating dendritic cells. Ultrasonic cavitation (UC) produces microbubbles that can transport immune enhancers directly, thus strengthening the immune response and therapeutic impact. Sonodynamic therapy (SDT) merges nanotechnology with immunotherapy, using specialized sonosensitizers to kill cancer cells and stimulate immune responses, increasing treatment success. This review discusses the integration of ultrasound-responsive nanosystems in tumor immunotherapy, exploring future opportunities and current hurdles.

Comparative Study of Sonodynamic and Photoactivated Cancer Therapies with Re(I)-Tricarbonyl Complexes Comprising Phenanthroline Ligands

Herein, we have compared the effectivity of light-based photoactivated cancer therapy and ultrasound-based sonodynamic therapy with Re(I)-tricarbonyl complexes (Re1-Re3) against cancer cells. The observed photophysical and TD-DFT calculations indicated the potential of Re1-Re3 to act as good anticancer agents under visible light/ultrasound exposure. Re1 did not display any dark- or light- or ultrasound-triggered anticancer activity. However, Re2 and Re3 displayed concentration-dependent anticancer activity upon light and ultrasound exposure. Interestingly, Re3 produced 1O2 and OH• on light/ultrasound exposure. Moreover, Re3 induced NADH photo-oxidation in PBS and produced H2O2. To the best of our knowledge, NADH photo-oxidation has been achieved here with the Re(I) complex for the first time in PBS. Additionally, Re3 released CO upon light/ultrasound exposure. The cell death mechanism revealed that Re3 produced an apoptotic cell death response in HeLa cells via ROS generation. Interestingly, Re3 showed slightly better anticancer activity under light exposure compared to ultrasound exposure.

An update on alternative therapy for Escherichia coli causing urinary tract infections; a narrative review

BACKGROUND

Urinary tract infections (UTIs) are the most common type of nosocomial infection and severe health issues because of the difficulties and frequent recurrence. Today, alternative methods such as sonodynamic therapy (SDT), photodynamic therapy (PDT) and herbal materials use for treating infections like UTI in many countries.

METHOD

We conducted searches of the biomedical databases (Google Scholar, Scopus, PubMed, and Web of sciences) to identify related studies from 2008 to 2023.

RESULT

SDT aims to use ultrasound to activate a sonosensitizer, which causes a biological effect by raising reactive oxygen species (ROS). When bacteria are exposed to ROS, several important effects occur: oxidative damage, DNA damage, protein dysfunction etc. SDT with herbal medicine significantly reduced the number of colony-forming units and bactericidal activity for Klebsiella pneumonia and E. coli. PDT is a promising treatment for cancer and microbial infections, combining a photosensitiser, light and tissue molecular oxygen. It involves a photosensitizer, light source, and oxygen, with variations affecting microbial binding and bactericidal activity. Factors affecting antibacterial properties include plant type, growing conditions, harvesting, and processing. This review highlights the recent advancements in sonodynamic, photodynamic, herbal, and bio-material-based approaches in the treatment of E. coli infections.

CONCLUSIONS

These alternative therapies offer exciting prospects for addressing UTIs, especially in cases where traditional antibiotic treatments may be less effective. Further research and clinical studies are warranted to fully explore the potential of these innovative treatment modalities in combating UTIs and improving patient outcomes.

Exploring Different Ultrasonic Parameters and Treatment Conditions to Optimize In Vitro Sonodynamic Therapeutic Effects in Cancer Cells

The effects of ultrasonic parameters and treatment conditions on the in vitro cellular experiments of sonodynamic therapy (SDT) have not been fully studied. Exploring the factors that affect the efficacy of SDT can provide a reference for screening effective sonosensitizers in vitro. The aim of this work is to investigate the factors that affected the SDT effects in cancer cells. Cancer cells in culture plates were exposed to ultrasound and sonosensitizers. The intracellular drug concentration was measured by using flow cytometry and the cell viability was determined by MTT assay. The SDT effects of cancer cells treated with different ultrasonic parameters under the same sonosensitizer concentration were different. The ultrasonic parameters, intracellular drug concentration, drug treatment time, cell amount, and cell status could affect the sonodynamic therapeutic effects. It is necessary to select appropriate ultrasound conditions and optimize the cellular status to make the results of the in vitro cellular experiments more reliable.

Design consideration of phthalocyanines as sensitizers for enhanced sono-photodynamic combinatorial therapy of cancer

Cancer remains one of the diseases with the highest incidence and mortality globally. Conventional treatment modalities have demonstrated threatening drawbacks including invasiveness, non-controllability, and development of resistance for some, including chemotherapy, radiation, and surgery. Sono-photodynamic combinatorial therapy (SPDT) has been developed as an alternative treatment modality which offers a non-invasive and controllable therapeutic approach. SPDT combines the mechanism of action of sonodynamic therapy (SDT), which uses ultrasound, and photodynamic therapy (PDT), which uses light, to activate a sensitizer and initiate cancer eradication. The use of phthalocyanines (Pcs) as sensitizers for SPDT is gaining interest owing to their ability to induce intracellular oxidative stress and initiate toxicity under SDT and PDT. This review discusses some of the structural prerequisites of Pcs which may influence their overall SPDT activities in cancer therapy.

Oxygen-Vacancy-Engineered W18 O49-x Nanobrush with a Suitable Band Structure for Highly Efficient Sonodynamic Therapy

With the rapid development of external minimally invasive or noninvasive therapeutic modalities, ultrasound-based sonodynamic therapy (SDT) is a new alternative for treating deep tumors. However, inadequate sonosensitizer efficiency and poor biosecurity limit clinical applications. In this study, we prepared an oxygen-vacancy-engineered W18 O49-x nanobrush with a band gap of 2.79 eV for highly efficient SDT using a simple solvothermal method. The suitable band structures of the W18 O49-x nanobrush endows it with the potential to simultaneously produce singlet oxygen (1 O2 ), superoxide anions (⋅O2 - ), and hydroxyl radicals (⋅OH) under ultrasound irradiation. Additionally, abundant oxygen vacancies that serve as further charge traps that inhibit electron-hole recombination are incidentally introduced through one-step thermal reduction. Collectively, the in vitro and in vivo results demonstrate that the oxygen-vacancy-engineered W18 O49-x nanobrush delivers highly efficient reactive oxygen species (ROS) for SDT in a very biosafe manner. Overall, this study provides a new avenue for discovering and designing inorganic nanosonosensitizers with enhanced therapeutic efficiencies for use in SDT.

From biomaterials to biotherapy: cuttlefish ink with protoporphyrin IX nanoconjugates for synergistic sonodynamic-photothermal therapy

Biologically produced nanomaterials capable of therapeutic purposes have received increasing interest in tumor therapy because of their intrinsic biocompatibility. In this study, we made cuttlefish ink (extracted from cuttlefish) and protoporphyrin IX (PpIX) nanoconjugates (CIPs) where PpIX was an endogenous organic compound. In the case of CIPs, PpIX could be triggered by ultrasound (US) for sonodynamic therapy (SDT), and the cuttlefish ink could be excited by a near-infrared laser for photothermal therapy (PTT). Thereafter, tumor growth was greatly inhibited through synergistic SDT-PTT in comparison to single SDT or PTT. In addition, in vivo administration of CIPs showed no noticeable side effects for mouse blood and chief organs, providing an effective strategy for developing biologically produced biomaterials and using them for biotherapy.

Evaluation the Effect of Sonodynamic Therapy with 5-Aminolevulinic Acid and Sodium Fluorescein by Preclinical Animal Study

Sonodynamic therapy (SDT) is a novel tumor treatment that combines biosafe sonosensitizers and noninvasive focused ultrasound to eradicate solid tumors. Sonosensitizers such as 5-aminolevulinic acid and fluorescein have great potential in tumor treatment. Here, rodent subcutaneous and brain tumor models were used to evaluate the treatment effect of both 5-ALA- and fluorescein-mediated SDT. The subcutaneous tumor growth rates of both SDT groups were significantly inhibited compared with that of the control groups. For intracranial tumors, 5-ALA-SDT treatment significantly inhibited brain tumor growth, while fluorescein-SDT exerted no therapeutic effect in animals. The distribution of fluorescein in the brain tumor region underwent further assessment. Seven days post tumor implantation, experimental animals received fluorescein and were sacrificed for brain specimen collection. Analysis of the dissected brains revealed no fluorescence signals, indicating an absence of fluorescein accumulation in the early-stage glioma tissue. These data suggest that the fluorescein-SDT treatment response is closely related to the amount of accumulated fluorescein. This study reports the equivalent effects of 5-ALA and fluorescein on the treatment of somatic tumors. For orthotopic brain tumor models, tumor vascular permeability should be considered when choosing fluorescein as a sonosensitizer. In conclusion, both fluorescein and 5-ALA are safe and effective SDT sonosensitizers, and the tumor microenvironment and pathologic type should be considered in the selection of adequate sonosensitizers.

Drug repurposing: A novel strategy to target cancer stem cells and therapeutic resistance

Chemotherapy is an effortless and frequently used approach in cancer therapy. However, in most cases, it can only prolong life expectancy and does not guarantee a complete cure. Furthermore, chemotherapy is associated with severe adverse effects, one of the major complications of effective cancer therapy. In addition, newly published research outputs show that cancer stem cells are involved in cancer disease progression, drug resistance, metastasis, and recurrence and that they are functional in the trans-differentiation capacity of cancer stem cells to cancer cells in response to treatments. Novel strategies are therefore required for better management of cancer therapy. The prime approach would be to synthesize and develop novel drugs that need extensive resources, time, and endurance to be brought into therapeutic use. The subsequent approach would be to screen the anti-cancer activity of available non-cancerous drugs. This concept of repurposing non-cancer drugs as an alternative to current cancer therapy has become popular in recent years because using existing anticancer drugs has several adverse effects. Micronutrients have also been investigated for cancer therapy due to their significant anti-cancer effects with negligible or no side effects and availability in food sources. In this paper, we discuss an ideal hypothesis for screening available non-cancerous drugs with anticancer activity, with a focus on cancer stem cells and their clinical application for cancer treatment. Further, drug repurposing and the combination of micronutrients that can target both cancers and cancer stem cells may result in a better therapeutic approach leading to maximum tumor growth control.

5-aminolevulinic acid sonodynamic therapy for cutaneous squamous cell carcinoma

BACKGROUND

The treatment of deep-invasive cutaneous squamous cell carcinoma (cSCC) is difficult. Sonodynamic therapy (SDT) has showed advantages in large penetration depth, small trauma, good repeatability, high targeting selectivity and effective protection for intact structure and function of tissues and organs.

OBJECTIVE

To study the efficacy and safety of 5-aminolevulinic acid SDT (ALA-SDT) in the treatment of cSCC.

METHODS

The absorption and transformation of ALA after co-incubation with cSCC were detected by UV-Vis and fluorescence absorption. The production of reactive oxygen species (ROS) when protoporphyrin IX (PpIX) excited with ultrasound was detected by ROS detection probe. Cytotoxicity of ALA-SDT to cSCC was detected with cytotoxicity indicators. The tumor volume changes and tumor weight of mice after ALA-SDT were detected. The effects of ALA-SDT on the growth of mice were evaluated through the changes in body weight of mice. Biosafety of treatment was further evaluated by histopathology to determine whether the tissues and organs of mice were affected after ALA-SDT.

RESULTS

ALA can be absorbed and converted into PpIX when incubated with cSCC cells and produces ROS with ultrasound irradiation. ALA-SDT showed a significant cytotoxicity on cSCC cells. With one session of ALA-SDT in vivo, tumor growth was slowed but not stopped and would proceed once treatment was ended. ALA-SDT had no significant effect on body weight changes and major tissues and organs of the mice.

CONCLUSION

ALA-SDT could safely and reduce cSCC cells growth both in vitro and in vivo.

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.

Glucose oxidase and metal catalysts combined tumor synergistic therapy: mechanism, advance and nanodelivery system

Cancer has always posed a significant threat to human health, prompting extensive research into new treatment strategies due to the limitations of traditional therapies. Starvation therapy (ST) has garnered considerable attention by targeting the primary energy source, glucose, utilized by cancer cells for proliferation. Glucose oxidase (GOx), a catalyst facilitating glucose consumption, has emerged as a critical therapeutic agent for ST. However, mono ST alone struggles to completely suppress tumor growth, necessitating the development of synergistic therapy approaches. Metal catalysts possess enzyme-like functions and can serve as carriers, capable of combining with GOx to achieve diverse tumor treatments. However, ensuring enzyme activity preservation in normal tissue and activation specifically within tumors presents a crucial challenge. Nanodelivery systems offer the potential to enhance therapy effectiveness by improving the stability of therapeutic agents and enabling controlled release. This review primarily focuses on recent advances in the mechanism of GOx combined with metal catalysts for synergistic tumor therapy. Furthermore, it discusses various nanoparticles (NPs) constructs designed for synergistic therapy in different carrier categories. Finally, this review provides a summary of GOx-metal catalyst-based NPs (G-M) and offers insights into the challenges associated with G-M therapy, delivery design, and oxygen (O2) supply.

The use of nanomaterials in advancing photodynamic therapy (PDT) for deep-seated tumors and synergy with radiotherapy

Photodynamic therapy (PDT) has been under development for at least 40 years. Multiple studies have demonstrated significant anti-tumor efficacy with limited toxicity concerns. PDT was expected to become a major new therapeutic option in treating localized cancer. However, despite a shifting focus in oncology to aggressive local therapies, PDT has not to date gained widespread acceptance as a standard-of-care option. A major factor is the technical challenge of treating deep-seated and large tumors, due to the limited penetration and variability of the activating light in tissue. Poor tumor selectivity of PDT sensitizers has been problematic for many applications. Attempts to mitigate these limitations with the use of multiple interstitial fiberoptic catheters to deliver the light, new generations of photosensitizer with longer-wavelength activation, oxygen independence and better tumor specificity, as well as improved dosimetry and treatment planning are starting to show encouraging results. Nanomaterials used either as photosensitizers per se or to improve delivery of molecular photosensitizers is an emerging area of research. PDT can also benefit radiotherapy patients due to its complementary and potentially synergistic mechanisms-of-action, ability to treat radioresistant tumors and upregulation of anti-tumoral immune effects. Furthermore, recent advances may allow ionizing radiation energy, including high-energy X-rays, to replace external light sources, opening a novel therapeutic strategy (radioPDT), which is facilitated by novel nanomaterials. This may provide the best of both worlds by combining the precise targeting and treatment depth/volume capabilities of radiation therapy with the high therapeutic index and biological advantages of PDT, without increasing toxicities. Achieving this, however, will require novel agents, primarily developed with nanomaterials. This is under active investigation by many research groups using different approaches.

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.

Curcuminoid Chalcones: Synthesis, Stability, and New Neuroprotective and Sonosensitising Activities

The primary purpose of this work was to design and obtain a series of curcuminoid chalcone-NSAID hybrid derivatives. The ester-type hybrid compounds with ibuprofen (i), ketoprofen (ii), and naproxen (iii) were obtained in two ways, using the Claisen-Schmidt reaction and the Steglich esterification reaction. The designed molecules were successfully synthesised, and FT-IR, MS, and NMR spectroscopy confirmed their structures. Moreover, the cytotoxic effect of the sonodynamic therapy and the anti-inflammatory, antioxidant, and anticholinergic properties of some curcuminoid chalcones and curcuminoid chalcones hybrids were evaluated. The curcuminoid chalcone derivatives showed promising neuroprotective activity as sonosensitisers for sonodynamic therapy in the studied cell lines. Additionally, the stability of the ester-type hybrid compounds with promising activity was determined. The RP-HPLC method was used to observe the degradation of the tested compounds. Studies have shown that structural isomers of ester-type hybrid compounds (3ai, 3bi) are characterised by a similar susceptibility to degradation factors, i.e., they are extremely unstable in alkaline environments, very unstable in acidic environments, unstable in neutral environments, practically stable in oxidising environments, and photolabile in solutions and in the solid phase. These compounds maintain adequate stability in environment at pH 1.2 and 6.8, which may make them good candidates for developing formulations for oral administration.

Functional anti-bone tumor biomaterial scaffold: construction and application

Bone tumors, including primary bone tumors and bone metastases, have been plagued by poor prognosis for decades. Although most tumor tissue is removed, clinicians are still confronted with the dilemma of eliminating residual cancer cells and regenerating defective bone tissue after surgery. Therefore, functional biomaterial scaffolds are considered to be the ideal candidates to bridge defective tissues and restrain cancer recurrence. Through functionalized structural modifications or coupled therapeutic agents, they provide sufficient mechanical strength and osteoinductive effects while eliminating cancer cells. Numerous novel approaches such as photodynamic, photothermal, drug-conjugated, and immune adjuvant-assisted therapies have exhibited remarkable efficacy against tumors while exhibiting low immunogenicity. This review summarizes the progress of research on biomaterial scaffolds based on different functionalization strategies in bone tumors. We also discuss the feasibility and advantages of the combined application of multiple functionalization strategies. Finally, potential obstacles to the clinical translation of anti-tumor bone bioscaffolds are highlighted. This review will provide valuable references for future advanced biomaterial scaffold design and clinical bone tumor therapy.

Ultrasound Sonosensitizers for Tumor Sonodynamic Therapy and Imaging: A New Direction with Clinical Translation

With the rapid development of sonodynamic therapy (SDT), sonosensitizers have evolved from traditional treatments to comprehensive diagnostics and therapies. Sonosensitizers play a crucial role in the integration of ultrasound imaging (USI), X-ray computed tomography (CT), and magnetic resonance imaging (MRI) diagnostics while also playing a therapeutic role. This review was based on recent articles on multifunctional sonosensitizers that were used in SDT for the treatment of cancer and have the potential for clinical USI, CT, and MRI applications. Next, some of the shortcomings of the clinical examination and the results of sonosensitizers in animal imaging were described. Finally, this paper attempted to inform the future development of sonosensitizers in the field of integrative diagnostics and therapeutics and to point out current problems and prospects for their application.

A Novel Platform of MOF for Sonodynamic Therapy Advanced Therapies

Metal-organic frameworks (MOFs) combined with sonodynamic therapy (SDT) have been introduced as a new and efficient treatment method. The critical advantage of SDT is its ability to penetrate deep tissues and concentrate energy on the tumor site to achieve a non-invasive or minimally invasive effect. Using a sonosensitizer to generate reactive oxygen species (ROS) under ultrasound is the primary SDT-related method of killing tumor cells. In the presence of a sonosensitizer, SDT exhibits a more lethal effect on tumors. The fast development of micro/nanotechnology has effectively improved the efficiency of SDT, and MOFs have been broadly evaluated in SDT due to their easy synthesis, easy surface functionalization, high porosity, and high biocompatibility. This article reviews the main mechanism of action of sonodynamic therapy in cancer treatment, and also reviews the applications of MOFs in recent years. The application of MOFs in sonodynamic therapy can effectively improve the targeting ability of SDT and the conversion ability of reactive oxygen species, thus improving their killing ability on cancer cells. This provides new ideas for the application of micro/nano particles in SDT and cancer therapy.

Harnessing Nanomaterials for Cancer Sonodynamic Immunotherapy

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

Curcumin-Triterpene Type Hybrid as Effective Sonosensitizers for Sonodynamic Therapy in Oral Squamous Cell Carcinoma

Sonodynamic therapy (SDT) is a non-invasive therapeutic modality in cancer treatment that combines low-intensity ultrasound (US) and sonosensitizers. Tumor cells are destroyed through the synergistic effects of ultrasound and a chemical sonosensitizer. This study focused on the synthesis and in vitro evaluation of the sonodynamic effect of natural curcumin, triterpene oleanolic acid, and their semi-synthetic derivatives on tongue cancer SCC-25 and hypopharyngeal FaDu cell lines. The combination of the tested compounds with sonication showed a synergistic increase in cytotoxicity. In the group of oleanolic acid derivatives, oleanoyl hydrogen succinate (6) showed the strongest cytotoxic effect both in the SCC-25 and FaDu cell lines. Comparing curcumin (4) and its pyrazole derivative (5), curcumin showed a better cytotoxic effect on SCC-25 cells, while curcumin pyrazole was more potent on FaDu cells. The highest sonotherapeutic activity, compared to its individual components, was demonstrated by a structural linker mode hybrid containing both curcumin pyrazole-oleanoyl hydrogen succinate units within one complex molecule (7). This study can be beneficial in the context of new perspectives in the search for effective sonosensitizers among derivatives of natural organic compounds.

Combinations of Photodynamic Therapy with Other Minimally Invasive Therapeutic Technologies against Cancer and Microbial Infections

The rapid rise in research and development following the discovery of photodynamic therapy to establish novel photosensitizers and overcome the limitations of the technology soon after its clinical translation has given rise to a few significant milestones. These include several novel generations of photosensitizers, the widening of the scope of applications, leveraging of the offerings of nanotechnology for greater efficacy, selectivity for the disease over host tissue and cells, the advent of combination therapies with other similarly minimally invasive therapeutic technologies, the use of stimulus-responsive delivery and disease targeting, and greater penetration depth of the activation energy. Brought together, all these milestones have contributed to the significant enhancement of what is still arguably a novel technology. Yet the major applications of photodynamic therapy still remain firmly located in neoplasms, from where most of the new innovations appear to launch to other areas, such as microbial, fungal, viral, acne, wet age-related macular degeneration, atherosclerosis, psoriasis, environmental sanitization, pest control, and dermatology. Three main value propositions of combinations of photodynamic therapy include the synergistic and additive enhancement of efficacy, the relatively low emergence of resistance and its rapid development as a targeted and high-precision therapy. Combinations with established methods such as chemotherapy and radiotherapy and demonstrated applications in mop-up surgery promise to enhance these top three clinical tools. From published in vitro and preclinical studies, clinical trials and applications, and postclinical case studies, seven combinations with photodynamic therapy have become prominent research interests because they are potentially easily applied, showing enhanced efficacy, and are rapidly translating to the clinic. These include combinations with chemotherapy, photothermal therapy, magnetic hyperthermia, cold plasma therapy, sonodynamic therapy, immunotherapy, and radiotherapy. Photochemical internalization is a critical mechanism for some combinations.

Characterization and Quantitation of the Tumor Microenvironment of Uveal Melanoma

Uveal melanoma (UM) is a highly malignant tumor of the eye. Metastatic spread of UM occurs almost exclusively via blood vessels and is of tremendous interest, as half of the patients with uveal melanoma die of metastasis in the long run. The tumor microenvironment consists of all cellular and non-cellular compounds of a solid tumor, except for the tumor cells. This study aims to provide a more detailed understanding of the tumor microenvironment of UM to build the foundation for new therapeutic targets. Fluorescence immunohistochemistry was performed to examine the localization of various cell types in the tumor microenvironment in UM. Furthermore, the presence of LAG-3 and its ligands Galectine-3 and LSECtin was examined to evaluate the potential efficacy of immune checkpoint inhibitor-based therapies. The main findings are that blood vessels are mainly located in the middle of the tumor, and that immune cells are mostly found in the outer section of the tumor. LAG-3 and Galectine-3 were found to be highly represented, whereas LSECtin barely occurred in UM. Both the predominant location of tumor-associated macrophages in the outer section of the tumor and the high presence of LAG-3 and Galectine-3 in the UM serve as attainable therapeutic targets.

Ultrasonic interfacial crosslinking of TiO2-based nanocomposite hydrogels through thiol-norbornene reactions for sonodynamic antibacterial treatment

Nanocomposite (NC) hydrogels used for sonodynamic therapy (SDT) face challenges such as lacking interfacial interactions between the polymers and nanomaterials as well as presenting uneven dispersion of nanomaterials in the hydrogel network, reducing their mechanical properties and treatment efficiency. Here, we demonstrate a promising approach of co-engineering nanomaterials and interfacial crosslinking to expand the materials construction and biomedical applications of NC hydrogels in SDT. In this work, mesoporous silica-coated titanium dioxide nanoparticles with thiolated surface functionalization (TiO₂@MS-SH) are utilized as crosslinkers to react with norbornene-functionalized dextran (Nor-Dex) through ultrasound-triggered thiol-norbornene reactions, forming TiO₂@MS-SH/Nor-Dex NC hydrogels. The TiO₂@MS-SH nanoparticles act not only as multivalent crosslinkers to improve the mechanical properties of hydrogels under ultrasound irradiation but also as reactive oxygen species (ROS) generators to allow the use of TiO₂@MS-SH/Nor-Dex NC hydrogels in SDT applications. Particularly, the TiO₂@MS-SH/Nor-Dex NC hydrogels present tailorable microstructures, properties, and sonodynamic killing of bacteria through the modulation of the ultrasound frequency. Taken together, a versatile TiO₂-based NC hydrogel platform prepared under ultrasonic interfacial crosslinking reactions is developed for advancing the applications in SDT.

Ultrasound nanomedicine and materdicine

The conventional microbubble-based ultrasound biomedicine clinically plays a vital role in providing the dynamic detection of macro and microvasculature and disease theranostics. However, the intrinsic limitation of particle size severely decreases the treatment effectiveness due to their vascular transport characteristics, which promotes the development and application of multifunctional ultrasound-responsive nanomaterials. Herein, we put forward a research field of "ultrasound nanomedicine and materdicine", referring to the interdiscipline of ultrasound, nanobiotechnology and materials, which seeks to produce specific biological effects for addressing the challenges faced and dilemma of conventional ultrasound medicine. We comprehensively summarize the state-of-the-art scientific advances in the latest progress in constructing ultrasound-based platforms and ultrasound-activated sonosensitizers, ranging from the synthesis strategies, biological functions to ultrasound-triggered therapeutic applications. Ultimately, the unresolved challenges and clinical-translation potentials of ultrasound nanomedicine and materdicine are discussed and prospected in this evolving field.

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

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

Metal Complexes for Cancer Sonodynamic Therapy

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

Titanium-Based Nanoarchitectures for Sonodynamic Therapy-Involved Multimodal Treatments

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

Tumor Spheroids as Model to Design Acoustically Mediated Drug Therapies: A Review

Tumor spheroids as well as multicellular tumor spheroids (MCTSs) are promising 3D in vitro tumor models for drug screening, drug design, drug targeting, drug toxicity, and validation of drug delivery methods. These models partly reflect the tridimensional architecture of tumors, their heterogeneity and their microenvironment, which can alter the intratumoral biodistribution, pharmacokinetics, and pharmacodynamics of drugs. The present review first focuses on current spheroid formation methods and then on in vitro investigations exploiting spheroids and MCTS for designing and validating acoustically mediated drug therapies. We discuss the limitations of the current studies and future perspectives. Various spheroid formation methods enable the easy and reproducible generation of spheroids and MCTSs. The development and assessment of acoustically mediated drug therapies have been mainly demonstrated in spheroids made up of tumor cells only. Despite the promising results obtained with these spheroids, the successful evaluation of these therapies will need to be addressed in more relevant 3D vascular MCTS models using MCTS-on-chip platforms. These MTCSs will be generated from patient-derived cancer cells and nontumor cells, such as fibroblasts, adipocytes, and immune cells.

Photodynamic therapy: Innovative approaches for antibacterial and anticancer treatments

Photodynamic therapy is an alternative treatment mainly for cancer but also for bacterial infections. This treatment dates back to 1900 when a German medical school graduate Oscar Raab found a photodynamic effect while doing research for his doctoral dissertation with Professor Hermann von Tappeiner. Unexpectedly, Raab revealed that the toxicity of acridine on paramecium depends on the intensity of light in his laboratory. Photodynamic therapy is therefore based on the administration of a photosensitizer with subsequent light irradiation within the absorption maxima of this substance followed by reactive oxygen species formation and finally cell death. Although this treatment is not a novelty, there is an endeavor for various modifications to the therapy. For example, selectivity and efficiency of the photosensitizer, as well as irradiation with various types of light sources are still being modified to improve final results of the photodynamic therapy. The main aim of this review is to summarize anticancer and antibacterial modifications, namely various compounds, approaches, and techniques, to enhance the effectiveness of photodynamic therapy.

The in-vitro proliferation-suppression of MCF-7 and HeLa cell lines mediated by differently substituted ionic phthalocyanines in sonodynamic therapy supplemented-photodynamic therapy

This work focuses on the study of the effects of the ultrasonic frequency (MHz) and power (W.cm^-2) on the stability, reactive oxygen species yields and cytotoxicity activities of differently substituted ionic phthalocyanines (Pcs) in sonodynamic therapy (SDT). Four ultrasonic parameters were investigated: Par I (1 MHz: 1 W.cm^-2), Par II (1 MHz: 2 W.cm^-2), Par III (3 MHz: 1 W.cm^-2) and Par IV (3 MHz: 2 W.cm^-2). A higher degradation of the Pcs was observed with increasing power at the Par II. Two reactive oxygen species (ROS) were detected in the ultrasound treated Pcs: singlet oxygen and hydroxyl radicals. Due to minimal degradation of most Pcs, Par I was chosen for SDT, photodynamic therapy (PDT), and photo-sonodynamic therapy (PSDT) against Michigan Cancer Foundation-7 and Henrietta Lacks cancer cell lines. PSDT generally showed improved therapeutic efficacies of the Pcs compared to the SDT and PDT mono treatments.

Mitochondria-targeting sonosensitizer-loaded extracellular vesicles for chemo-sonodynamic therapy

Sonodynamic therapy (SDT) has emerged as an effective therapeutic modality as it employs ultrasound (US) to eradicate deep-seated tumors noninvasively. However, the therapeutic efficacy of SDT in clinical settings remains limited owing to the low aqueous stability and poor pharmacokinetic properties of sonosensitizers. In this study, extracellular vesicles (EVs), which have low systemic toxicity, were used as clinically available nanocarriers to effectively transfer a sonosensitizer to cancer cells. Chlorin e6 (Ce6), a sonosensitizer, was conjugated to a mitochondria-targeting triphenylphosphonium (TPP) moiety and loaded into EVs to enhance the efficacy of SDT, because mitochondria are critical subcellular organelles that regulate cell survival and death. Additionally, piperlongumine (PL), a pro-oxidant and cancer-specific chemotherapeutic agent, was co-encapsulated into EVs to achieve efficient and selective anticancer activity. The EVs substantially amplified the cellular internalization of TPP-conjugated Ce6 (TPP-Ce6), resulting in the enhanced generation of intracellular reactive oxygen species (ROS) in MCF-7 human breast cancer cells upon US exposure. Importantly, EVs encapsulating TPP-Ce6 effectively destroyed the mitochondria under irradiation with US, leading to efficient anticancer activity. The co-encapsulation of pro-oxidant PL into EVs significantly enhanced the SDT efficacy in MCF-7 cells through the excessive generation of ROS. Moreover, the EV co-encapsulating TPP-Ce6 and PL [EV(TPP-Ce6/PL)] exhibited cancer-specific cell death owing to the cancer-selective apoptosis triggered by PL. In vivo study using MCF-7 tumor-xenograft mice revealed that EV(TPP-Ce6/PL) effectively accumulated in tumors after intravenous injection. Notably, treatment with EV(TPP-Ce6/PL) and US inhibited tumor growth significantly without causing systemic toxicity. This study demonstrated the feasibility of using EV(TPP-Ce6/PL) for biocompatible and cancer-specific chemo-SDT.

Ultrasound-excited temozolomide sonosensitization induces necroptosis in glioblastoma

Temozolomide (TMZ) has been determined to be the chemotherapeutic drug with efficacy for glioblastoma (GBM). Thus, potentiating the therapeutic effect of TMZ can undoubtedly yield twice the result with half the effort. In this study, we found for the first time that TMZ can produce reactive oxygen species (ROS) under the influence of ultrasound (US). This property allows TMZ-US therapy to have better efficacy in the treatment of GBM. Given that the increasing use of US in central nervous system (CNS) diseases and the importance of TMZ for GBM therapy, our results will facilitate the development of TMZ-associated glioblastoma therapies. Moreover, we found that chemotherapeutic drugs might have the ability to generate ROS under the excitation of US. On a larger scale, our findings may be applicable to a wide range of known drugs.

Development of a Polymersome-Based Nanomedicine for Chemotherapeutic and Sonodynamic Combination Therapy

In anticancer therapy, combination therapy has been suggested as an alternative to the insufficient therapeutic efficacy of single therapy. Among combination therapies, combination chemo- and photodynamic therapy are actively investigated. However, photodynamic therapy shows a limitation in the penetration depth of the laser. Therefore, sonodynamic therapy (SDT), using ultrasound instead of a laser as a trigger, is an upcoming strategy for deep tumors. Additionally, free drugs are easily degraded by enzymes, have difficulty in reaching the target site, and show side effects after systemic administration; therefore, the development of drug delivery systems is desirable for sufficient drug efficacy for combination therapy. However, nanocarriers, such as microbubbles, and albumin nanoparticles, are unstable in the body and show low drug-loading efficiency. Here, we propose polylactide (PLA)-poly (ethylene glycol) (PEG) polymersomes (PLs) with a high drug loading rate of doxorubicin (DOX) and verteporfin (VP) for effective combination therapy in both in vitro and in vivo experiments. The cellular uptake efficiency and cytotoxicity test results of VP-DOX-PLs were higher than that of single therapy. Moreover, in vivo biodistribution showed the accumulation of the VP-DOX-PLs in tumor regions. Therefore, VP-DOX-PLs showed more effective anticancer efficacy than either single therapy in vivo. These results suggest that the combination therapy of SDT and chemotherapy could show novel anticancer effects using VP-DOX-PLs.

Innovative nanotheranostics: Smart nanoparticles based approach to overcome breast cancer stem cells mediated chemo- and radioresistances

The alarming increase in the number of breast cancer patients worldwide and the increasing death rate indicate that the traditional and current medicines are insufficient to fight against it. The onset of chemo- and radioresistances and cancer stem cell-based recurrence make this problem harder, and this hour needs a novel treatment approach. Competent nanoparticle-based accurate drug delivery and cancer nanotheranostics like photothermal therapy, photodynamic therapy, chemodynamic therapy, and sonodynamic therapy can be the key to solving this problem due to their unique characteristics. These innovative formulations can be a better cargo with fewer side effects than the standard chemotherapy and can eliminate the stability problems associated with cancer immunotherapy. The nanotheranostic systems can kill the tumor cells and the resistant breast cancer stem cells by novel mechanisms like local hyperthermia and reactive oxygen species and prevent tumor recurrence. These theranostic systems can also combine with chemotherapy or immunotherapy approaches. These combining approaches can be the future of anticancer therapy, especially to overcome the breast cancer stem cells mediated chemo- and radioresistances. This review paper discusses several novel theranostic systems and smart nanoparticles, their mechanism of action, and their modifications with time. It explains their relevance and market scope in the current era. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Nanosensitizer-mediated unique dynamic therapy tactics for effective inhibition of deep tumors

X-ray and ultrasound waves are widely employed for diagnostic and therapeutic purposes in clinic. Recently, they have been demonstrated to be ideal excitation sources that activate sensitizers for the dynamic therapy of deep-seated tumors due to their excellent tissue penetration. Here, we focused on the recent progress in five years in the unique dynamic therapy strategies for the effective inhibition of deep tumors that activated by X-ray and ultrasound waves. The concepts, mechanisms, and typical nanosensitizers used as energy transducers are described as well as their applications in oncology. The future developments and potential challenges are also discussed. These unique therapeutic methods are expected to be developed as depth-independent, minimally invasive, and multifunctional strategies for the clinic treatment of various deep malignancies.

Focused ultrasound-mediated small-molecule delivery to potentiate immune checkpoint blockade in solid tumors

In the last decade, immune checkpoint blockade (ICB) has revolutionized the standard of treatment for solid tumors. Despite success in several immunogenic tumor types evidenced by improved survival, ICB remains largely unresponsive, especially in "cold tumors" with poor lymphocyte infiltration. In addition, side effects such as immune-related adverse events (irAEs) are also obstacles for the clinical translation of ICB. Recent studies have shown that focused ultrasound (FUS), a non-invasive technology proven to be effective and safe for tumor treatment in clinical settings, could boost the therapeutic effect of ICB while alleviating the potential side effects. Most importantly, the application of FUS to ultrasound-sensitive small particles, such as microbubbles (MBs) or nanoparticles (NPs), allows for precise delivery and release of genetic materials, catalysts and chemotherapeutic agents to tumor sites, thus enhancing the anti-tumor effects of ICB while minimizing toxicity. In this review, we provide an updated overview of the progress made in recent years concerning ICB therapy assisted by FUS-controlled small-molecule delivery systems. We highlight the value of different FUS-augmented small-molecules delivery systems to ICB and describe the synergetic effects and underlying mechanisms of these combination strategies. Furthermore, we discuss the limitations of the current strategies and the possible ways that FUS-mediated small-molecule delivery systems could boost novel personalized ICB treatments for solid tumors.

Recent Clinical and Preclinical Advances in External Stimuli-Responsive Therapies for Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) has long been one of the most prevalent cancers worldwide; even though treatments such as surgery, chemotherapy, radiotherapy and immunotherapy have been proven to benefit the patients and prolong their survival time, the overall five-year survival rate is still below 50%. Hence, the development of new therapies for better patient management is an urgent need. External stimuli-responsive therapies are emerging therapies with promising antitumor effects; therapies such as photodynamic (PDT) and photothermal therapies (PTT) have been tested clinically in late-stage HNSCC patients and have achieved promising outcomes, while the clinical translation of sonodynamic therapy (SDT), radiodynamic therapy (RDT), microwave dynamic/thermodynamic therapy, and magnetothermal/magnetodynamic therapy (MDT/MTT) still lag behind. In terms of preclinical studies, PDT and PTT are also the most extensively studied therapies. The designing of nanoparticles and combinatorial therapies of PDT and PTT can be referenced in designing other stimuli-responsive therapies in order to achieve better antitumor effects as well as less toxicity. In this review, we consolidate the advancements and limitations of various external stimuli-responsive therapies, as well as critically discuss the prospects of this type of therapies in HNSCC treatments.

Newly developed gas-assisted sonodynamic therapy in cancer treatment

Sonodynamic therapy (SDT) is an emerging noninvasive treatment modality that utilizes low-frequency and low-intensity ultrasound (US) to trigger sensitizers to kill tumor cells with reactive oxygen species (ROS). Although SDT has attracted much attention for its properties including high tumor specificity and deep tissue penetration, its anticancer efficacy is still far from satisfactory. As a result, new strategies such as gas-assisted therapy have been proposed to further promote the effectiveness of SDT. In this review, the mechanisms of SDT and gas-assisted SDT are first summarized. Then, the applications of gas-assisted SDT for cancer therapy are introduced and categorized by gas types. Next, therapeutic systems for SDT that can realize real-time imaging are further presented. Finally, the challenges and perspectives of gas-assisted SDT for future clinical applications are discussed.

Synergistic Phenomena between Iron-Doped ZnO Nanoparticles and Shock Waves Exploited against Pancreatic Cancer Cells

We propose the use of iron-doped zinc oxide nanoparticles (Fe:ZnO NPs) showing theranostic capabilities and being synergistically active against pancreatic ductal adenocarcinoma once combined with mechanical pressure waves, such as shock waves. Fe:ZnO NPs are synthesized by employing oleic acid as a capping agent and are functionalized with amino-propyl groups. We first report their superior characteristics with respect to undoped ZnO NPs in terms of magnetic properties, colloidal stability, cytocompatibility, and internalization into BxPC-3 pancreatic cancer cells in vitro. These Fe:ZnO NPs are also cytocompatible toward normal pancreatic cells. We then perform a synergistic cell treatment with both shock waves and Fe:ZnO NPs once internalized into cells. We also evaluate the contribution to the synergistic activity of the NPs located in the extracellular space. Results show that both NPs and shock waves, when administered separately, are safe to cells, while their combination provokes an enhanced cell death after 24 h. Various mechanisms are then considered, such as dissolution of NPs, production of free radicals, and cell membrane disruption or permeation. It is understood so far that iron-doped ZnO NPs can degrade intracellularly into zinc cations, while the use of shock waves produce cell membrane permeabilization and possible rupture. In contrast, the production of reactive oxygen species is here ruled out. The provoked cell death can be recognized in both apoptotic and necrotic events. The proposed work is thus a first proof-of-concept study enabling promising future applications to deep-seated tumors such as pancreatic cancer, which is still an unmet clinical need with a tremendous death rate.

Gold nanoparticle decoration potentiate the antibacterial enhancement of TiO2 nanotubes via sonodynamic therapy against peri-implant infections

Inflammatory damage from bacterial biofilms usually causes the failure of tooth implantation. A promising solution for this challenge is to use an implant surface with a long-term, in-depth and efficient antibacterial feature. In this study, we developed an ultrasound-enhanced antibacterial implant surface based on Au nanoparticle modified TiO2 nanotubes (AuNPs-TNTs). As an artificial tooth surface, films based on AuNPs-TNTs showed excellent biocompatibility. Importantly, compared to bare titania surface, a larger amount of reactive oxygen radicals was generated on AuNPs-TNTs under an ultrasound treatment. For a proof-of-concept application, Porphyromonas gingivalis (P. gingivalis) was used as the model bacteria; the as-proposed AuNPs-TNTs exhibited significantly enhanced antibacterial activity under a simple ultrasound treatment. This antibacterial film offers a new way to design the surface of an artificial implant coating for resolving the bacterial infection induced failure of dental implants.

Peroxide mediated oxygen delivery in cancer therapy

Hypoxia is a serious obstacle in cancer treatment. The aberrant vascular network as well as the abnormal extracellular matrix arrangement results in formation of a hypoxic regions in tumors which show high resistance to the curing. Hypoxia makes the cancer treatment challengeable via two mechanisms; first and foremost, hypoxia changes the cell metabolism and leads the cells towards an aggressive and metastatic phenotype and second, hypoxia decreases the efficiency of the various cancer treatment modalities. Most of the cancer treatment methods including chemotherapy, radiotherapy, photodynamic therapy, sonodynamic therapy and immunotherapy are negatively affected by the oxygen deprivation. Therefore, the regional oxygenation is requisite to alleviate the negative impacts of the hypoxia on tumor cells and tumor therapy modalities. A great deal of effort has been put forth to resolve the problem of hypoxia in tumors. Peroxides have gained tremendous attention as oxygen generating components in cancer therapy. The concurrent loading of the peroxides and cancer treatment components into a single delivery system can bring about a multipurpose delivery system and substantially encourage the success of the cancer amelioration. In this review, we have tried to after the description of a relation between hypoxia and cancer treatment modalities, discuss the role of peroxides in tumor hyperoxygenation and cancer therapy success. Thereafter, we have summarized a number of vehicles for the delivery of the peroxide alone or in combination with other therapeutic components for cancer treatment.

Oxygen-Deficient Tungsten Oxide (WOx) Nanobelts with pH-Sensitive Degradation for Enhanced Sonodynamic Therapy of Cancer

The further bioapplications of sonodynamic therapy (SDT) were hindered by the inadequate efficiency and poor degradability of sonosensitizers and the hypoxic tumor microenvironment (TME). Therefore, it is ideal to develop pH-sensitive sonosensitizers that generate abundant reactive oxygen species (ROS) and rapidly degrade in a neutral environment while slowly degrading in an acidic environment to reduce their long-term toxicity. Herein, the defective tungsten oxide nanobelts (WO_x NBs) were developed as a type of pH-sensitive and biodegradable sonosensitizers with a high SDT efficiency and low toxicity for enhanced SDT. The defective oxygen sites of WO_x NBs could inhibit the recombination of electrons and holes, making WO_x NBs promising sonosensitizers that could generate abundant ROS under ultrasound (US) irradiation. Enhanced by the catalase (CAT) that reacted with H₂O₂ to generate O₂, the WO_x NBs exhibited better SDT performance against 4T1 cells in both normoxic and hypoxic environments. In addition, the WO_x NBs could degrade by releasing protons (H⁺), resulting in intracellular acidification and inhibited cell motility that further enhanced the therapeutic effects of SDT. Assisted with CAT and ALG for hypoxia refinement and better retention, the WO_x NBs enabled effective SDT and antimetastasis against 4T1 tumors in vivo. Most importantly, the WO_x NBs could degrade rapidly in normal tissues but slowly in an acidic TME, which was favorable for their fast clearance, without any obvious long-term toxicity. Our work developed defective WO_x NBs with a high SDT efficiency and pH-sensitive degradation for enhanced SDT, which extended the biomedical application of tungsten-based nanomaterials and the further development of SDT.

MnO2 coated multi-layer nanoplatform for enhanced sonodynamic therapy and MR imaging of breast cancer

Sonodynamic therapy (SDT) is a promising new anti-tumor therapy that inhibits tumor growth by ultrasound activation of sonosensitizers to produce reactive oxygen species (ROS). However, the problems of hypoxia in the microenvironment within solid tumors and the effectiveness of SDT will decrease due to the little accumulation of sonosensitizers at the tumor site, as well as tumor cell tolerance, have limited the development of SDT. To overcome these problems, a core-shell structured nanoparticle (IR780/PLGA@MnO2 NPs) loaded with IR780 and manganese dioxide (MnO2) was developed as a nanocarrier to transport the sonosensitizer IR780 and the generated oxygen into the tumor tissue. The MnO2 shell layer of IR780/PLGA@MnO2 NPs can prevent the premature release of IR780 in the blood and also it can react with acidic and high H2O2, the generated oxygen can relieve tumor tissue hypoxia, and the generated Mn can enhance magnetic resonance imaging (MRI) signal intensity by acting as a contrast agent for MRI. More importantly, the released IR780 can produce ROS to kill tumor cells under ultrasound excitation. This PH-responsive and H2O2-triggered SDT based on the IR780/PLGA@MnO2NPs is an effective platform to inhibit tumor growth with negligible systemic toxicity. This work develops a multifunctional therapeutic integrated nanoplatform for breast cancer treatment, which is expected to be used in the clinic.

The promising interplay between sonodynamic therapy and nanomedicine

Sonodynamic therapy (SDT) is a non-invasive approach for cancer treatment in which chemical compounds, named sonosensitizers, are activated by non-thermal ultrasound (US), able to deeply penetrate into the tissues. Despite increasing interest, the underlying mechanisms by which US triggers the sonosensitizer therapeutic activity are not yet clearly elucidate, slowing down SDT clinical application. In this review we will discuss the main mechanisms involved in SDT with particular attention to the sonosensitizers involved for each described mechanism, in order to highlight how much important are the physicochemical properties of the sonosensitizers and their cellular localization to predict their bioeffects. Moreover, we will also focus our attention on the pivotal role of nanomedicine providing the sonodynamic anticancer approach with the ability to shape US-responsive agents to enhance specific sonodynamic effects as the sonoluminescence-mediated anticancer effects. Indeed, SDT is one of the biomedical fields that has significantly improved in recent years due to the increased knowledge of nanosized materials. The shift of the nanosystem from a delivery system for a therapeutic agent to a therapeutic agent in itself represents a real breakthrough in the development of SDT. In doing so, we have also highlighted potential areas in this field, where substantial improvements may provide a valid SDT implementation as a cancer therapy.

Recent developments of sonodynamic therapy in antibacterial application

The rapid emergence of pathogenic bacteria poses a serious threat to global health. Notably, traditional antibiotic therapies suffer from the risk of strengthening bacterial drug resistance. Sonodynamic therapy (SDT) combining sonosensitizers and low-intensity ultrasound (US) has broadened the way towards treating drug-resistant bacteria. The allure of this therapy emerges from the capacity to focus the US energy on bacterial infection sites buried deep in tissues, locally activating the sonosensitizers to produce cytotoxic reactive oxygen species (ROS) with the ability to induce bacterial death. The past decade has witnessed the rapid development of antibacterial SDT owing to their excellent penetration, favorable biocompatibility and specific targeting ability. This review summarizes available sonosensitizers for antibacterial SDT, and digs into innovative biotechnologies to improve SDT efficiency, such as enhancing the targeting ability of sonosensitizers, image-guided assisted SDT, improvement of hypoxia and combination of SDT with other therapies. Finally, we conclude with the present challenges and provide insights into the future research of antibacterial SDT.

Multicomponent Molecular Systems Based on Porphyrins, 1,3,5-Triazine and Carboranes: Synthesis and Characterization

2,4,6-Trichloro-1,3,5-triazine (cyanuric chloride) is an excellent coupling reagent for the preparation of highly structured multifunctional molecules. Three component systems based on porphyrin, cyanuric chloride and carborane clusters were prepared by a one-pot stepwise amination of cyanuric chloride with 5-(4-aminophenyl)-10,15,20-triphenylporphyrin, followed by replacement of the remaining chlorine atoms with carborane S- or N-nucleophiles. Some variants of 1,3,5-triazine derivatives containing porphyrin, carborane and residues of biologically active compounds such as maleimide, glycine methyl ester as well as thioglycolic acid, mercaptoethanol and hexafluoroisopropanol were also prepared. A careful control of the reaction temperature during the substitution reactions will allow the synthesis of desired compounds in a good to high yields. The structures of synthesized compounds were determined with UV-vis, IR, ¹H NMR, ¹¹B NMR, MALDI-TOF or LC-MS spectroscopic data. The dark and photocytotoxicity as well as intracellular localization and photoinduced cell death for compounds 8, 9, 17, 18 and 24 were evaluated.

The crosstalk between sonodynamic therapy and autophagy in cancer

As a noninvasive treatment approach for cancer and other diseases, sonodynamic therapy (SDT) has attracted extensive attention due to the deep penetration of ultrasound, good focusing, and selective irradiation sites. However, intrinsic limitations of traditional sonosensitizers hinder the widespread application of SDT. With the development of nanotechnology, nanoparticles as sonosensitizers or as a vehicle to deliver sonosensitizers have been designed and used to target tissues or tumor cells with high specificity and accuracy. Autophagy is a common metabolic alteration in both normal cells and tumor cells. When autophagy happens, a double-membrane autophagosome with sequestrated intracellular components is delivered and fused with lysosomes for degradation. Recycling these cell materials can promote survival under a variety of stress conditions. Numerous studies have revealed that both apoptosis and autophagy occur after SDT. This review summarizes recent progress in autophagy activation by SDT through multiple mechanisms in tumor therapies, drug resistance, and lipid catabolism. A promising tumor therapy, which combines SDT with autophagy inhibition using a nanoparticle delivering system, is presented and investigated.