Recent progress in development of new sonosensitizers for sonodynamic cancer therapy

Reactive oxygen species (ROS): utilizing injectable antioxidative hydrogels and ROS-producing therapies to manage the double-edged sword

Reactive oxygen species (ROS) are generated in cellular metabolism and are essential for cellular signalling networks and physiological functions. However, the functions of ROS are 'double-edged swords' to living systems that have a fragile redox balance between ROS generation and elimination. A modest increase of ROS leads to enhanced cell proliferation, survival and benign immune responses, whereas ROS stress that overwhelms the cellular antioxidant capacity can damage nucleic acids, proteins and lipids, resulting in oncogenic mutations and cell death. ROS are therefore involved in many pathological conditions. On the other hand, ROS present selective toxicity and have been utilised against cancer and pathogens, thus also acting as a double-edged sword in the healthcare field. Injectable antioxidative hydrogels are gel precursors that form hydrogel constructs in situ upon delivery in vivo to maintain an antioxidative capacity. These hydrogels have been developed to counter ROS-induced pathological conditions, with significant advantages of biocompatibility, excellent moldability, and minimally invasive delivery. The intrinsic, readily controllable ROS-scavenging ability of the functionalised hydrogels overcomes many drawbacks of small molecule antioxidants. This review summarises the roles of ROS under pathological conditions and describes the state-of-the-art of injectable antioxidative hydrogels. A particular emphasis is also given to current ROS-producing therapeutic interventions, enabling potential application of injectable antioxidant hydrogels to prevent the adverse effects of many cancer and infection treatments.

Nanoparticle-Assisted Sonosensitizers and Their Biomedical Applications

As a non-invasive strategy, sonodynamic therapy (SDT) which utilizes sonosensitizers to generate reactive oxygen species (ROS) has received significant interest over recent years due to its ability to break depth barrier. However, intrinsic limitations of traditional sonosensitizers hinder the widespread application of SDT. With the development of nanotechnology, various nanoparticles (NPs) have been designed and used to assist sonosensitizers for SDT. This review first summarizes the possible mechanisms of SDT, then classifies the NPs-assisted sonosensitizers and discusses their biomedical applications in ultrasonography, drug delivery, high intensity focused ultrasound and SDT-based combination treatment. Finally, some challenges and future perspectives of NPs-assisted SDT has also been discussed.

An understanding of mitochondria and its role in targeting nanocarriers for diagnosis and treatment of cancer

Nanotechnology has changed the entire paradigm of drug targeting and has shown tremendous potential in the area of cancer therapy due to its specificity. In cancer, several targets have been explored which could be utilized for the better treatment of disease. Mitochondria, the so-called powerhouse of cell, portrays significant role in the survival and death of cells, and has emerged as potential target for cancer therapy. Direct targeting and nanotechnology based approaches can be tailor-made to target mitochondria and thus improve the survival rate of patients suffering from cancer. With this backdrop, in present review, we have reemphasized the role of mitochondria in cancer progression and inhibition, highlighting the different targets that can be explored for targeting of disease. Moreover, we have also summarized different nanoparticulate systems that have been used for treatment of cancer via mitochondrial targeting.

Sonodynamic antimicrobial chemotherapy: An emerging alternative strategy for microbial inactivation

Sonodynamic antimicrobial chemotherapy (SACT), which relies on a combination of low-intensity ultrasound and chemotherapeutic agents termed sonosensitizers, has been explored as a promising alternative for microbial inactivation. Such treatment has superior penetration ability, high target specificity, and can overcome resistance conferred by the local microenvironment. Taken of these advantages, SACT has been endowed with an extensive application prospect in the past decade and attracted more and more attention. This review focusses on the current understanding of the mechanism of SACT, the interaction of sonodynamic action on different microbes, the factors affecting the efficacy of SACT, discusses the findings of recent works on SACT, and explores further prospects for SACT. Thus, a better understanding of sonodynamic killing facilitates the scientific community and industry personnel to establish a novel strategy to combat microbial burden.

A hypoxia responsive nanoassembly for tumor specific oxygenation and enhanced sonodynamic therapy

The hypoxic tumor microenvironment (TME) and non-specific distribution of sonosensitizers are two major obstacles that limit practical applications of sonodynamic therapy (SDT) in combating tumors. Here we report a hypoxia-responsive nanovesicle (hMVs) as delivery vehicles of a sonosensitizer to enhance the efficacy of SDT via specific payload release and local oxygenation in the tumor. The nanovesicles are composed of densely packed manganese ferrite nanoparticles (MFNs) embedded in hypoxia-responsive amphiphilic polymer membranes. With δ-aminolevulinic acid (ALA) loaded in the hollow cavities, the hMVs could rapidly dissociate into discrete nanoparticles in the hypoxic TME to release the payload and induce the generation of reactive oxygen species (ROS) under ultrasound (US) radiation. Meanwhile, the released MFNs could catalytically generate O₂ to overcome the hypoxic TME and thus enhance the efficacy of SDT. After treatment, the dissociated MFNs could be readily excreted from the body via renal clearance to reduce long term toxicity. In vitro and in vivo experiments displayed effective tumor inhibition via hMVs-mediated SDT, indicating the great potential of this unique nanoplatform in effective SDT by generating sufficient ROS in deep-seated hypoxic tumors that are not readily accessible by conventional photodynamic therapy.

Design and Challenges of Sonodynamic Therapy System for Cancer Theranostics: From Equipment to Sensitizers

As a novel noninvasive therapeutic modality combining low-intensity ultrasound and sonosensitizers, sonodynamic therapy (SDT) is promising for clinical translation due to its high tissue-penetrating capability to treat deeper lesions intractable by photodynamic therapy (PDT), which suffers from the major limitation of low tissue penetration depth of light. The effectiveness and feasibility of SDT are regarded to rely on not only the development of stable and flexible SDT apparatus, but also the screening of sonosensitizers with good specificity and safety. To give an outlook of the development of SDT equipment, the key technologies are discussed according to five aspects including ultrasonic dose settings, sonosensitizer screening, tumor positioning, temperature monitoring, and reactive oxygen species (ROS) detection. In addition, some state-of-the-art SDT multifunctional equipment integrating diagnosis and treatment for accurate SDT are introduced. Further, an overview of the development of sonosensitizers is provided from small molecular sensitizers to nano/microenhanced sensitizers. Several types of nanomaterial-augmented SDT are in discussion, including porphyrin-based nanomaterials, porphyrin-like nanomaterials, inorganic nanomaterials, and organic-inorganic hybrid nanomaterials with different strategies to improve SDT therapeutic efficacy. There is no doubt that the rapid development and clinical translation of sonodynamic therapy will be promoted by advanced equipment, smart nanomaterial-based sonosensitizer, and multidisciplinary collaboration.

Gadolinium-doped hollow silica nanospheres loaded with curcumin for magnetic resonance imaging-guided synergistic cancer sonodynamic-chemotherapy

Curcumin is a kind of anti-cancer chemotherapeutic drug and has been demonstrated to be able to produce reactive oxygen species (ROS) under the stimuli of ultrasound (US). Herein, gadolinium-doped hollow mesoporous silica nanospheres (Gd-HMSNs) loaded with curcumin (Cur) and conjugated with carboxymethyl dextran (CMD) have been facilely fabricated and applied for magnetic resonance imaging (MRI)-guided synergistic cancer sonodynamic-chemotherapy. The as-prepared multifunctional theranostic nanoplatform (Cur@Gd-HMSNs-CMD) shows high drug loading capacity, satisfactory biocompatibility, pH-responsive degradation, and US-triggered drug release. Due to the release of Gd³⁺ ions or oligomers during degradation, the nanoplatform Cur@Gd-HMSNs-CMD could serve as an effective contrast agent for T₁-weighted MRI to guide cancer treatment. More significantly, in vivo experiments show that the Cur@Gd-HMSNs-CMD can efficiently inhibit the tumor growth by a high inhibition rate of ~85.6% under US irradiation, mainly resulting from the synergistic effect of sonodynamic-chemotherapy. This innovative "two-in-one" theranostic nanoplatform using a single drug provides a new strategy for developing "all-in-one" nanomaterials for combined cancer treatment.

Janus Nanoparticles: From Fabrication to (Bio)Applications

Janus nanoparticles (JNPs) refer to the integration of two or more chemically discrepant composites into one structure system. Studies into JNPs have been of significant interest due to their interesting characteristics stemming from their asymmetric structures, which can integrate different functional properties and perform more synergetic functions simultaneously. Herein, we present recent progress of Janus particles, comprehensively detailing fabrication strategies and applications. First, the classification of JNPs is divided into three blocks, consisting of polymeric composites, inorganic composites, and hybrid polymeric/inorganic JNPs composites. Then, the fabrication strategies are alternately summarized, examining self-assembly strategy, phase separation strategy, seed-mediated polymerization, microfluidic preparation strategy, nucleation growth methods, and masking methods. Finally, various intriguing applications of JNPs are presented, including solid surfactants agents, micro/nanomotors, and biomedical applications such as biosensing, controlled drug delivery, bioimaging, cancer therapy, and combined theranostics. Furthermore, challenges and future works in this field are provided.

Photodynamic and Sonodynamic Therapy with Protoporphyrin IX: In Vitro and In Vivo Studies

Sono-photodynamic therapy is a promising anticancer technique based on the combination of sonodynamic and photodynamic therapy to improve the cancer treatment effectiveness. This study was aimed at analyzing the effects of the sono-photodynamic (SPD) activity on protoporphyrin IX (PpIX) solution and PpIX-loaded rat liver. In vitro, PpIX 5 μM solutions were irradiated with light (635 nm, 30-50 mW/cm²), ultrasound (1 MHz, 1-2 W/cm²) and both. The PpIX absorption spectra recorded over exposure time revealed that the PpIX decay rate induced by SPD activity (combined irradiation) was approximately the sum of those induced by photodynamic and sonodynamic activity. In vivo, rats were intraperitoneally injected with 5-aminolevulinic acid at the dose of 500 mg/kg weight. After 3 h of injection, the PpIX-loaded livers were irradiated with light (635 nm, 180 ± 9 J/cm²), ultrasound (1.0 MHz, 770 ± 40 J/cm²) and both using a single probe capable of illuminating and sonicating the liver simultaneously. After 30 h, the liver damage induced by each protocol was analyzed histologically. It was found that a greater necrosis depth was induced by the SPD activity. These results suggest that the SPD activity could improve the PpIX decay rate and have greater scope than photodynamic or sonodynamic activity. Further studies should be performed to gain a better understanding of this protocol.

Engineering oxygen-deficient ZrO2-x nanoplatform as therapy-activated "immunogenic cell death (ICD)" inducer to synergize photothermal-augmented sonodynamic tumor elimination in NIR-II biological window

Nano-zirconia, as an amphoteric semiconductor, has been industrially exploited in photocatalytic reactions and as piezoelectric sensors. However, its biomedical applications, especially in antitumor therapeutics, have been seldom investigated to date. Here, oxygen-deficient zirconia (ZrO_2-x)-based nanoplatform with surface PEGylation and cyclic-Arg-Gly-Asp (cRGD) peptide functionalization (ZrO_2-x@PEG/cRGD, abbreviated as ZPR) was rationally designed and established for the first time, which was utilized as therapy-activated "immunogenic cell death (ICD)" inducer to boost photothermal-augmented sonodynamic tumor elimination in NIR-II biological window. As-synthesized ZPR nanoparticles (NPs) exhibited intense optical absorbance in the wavelength range of 900-1100 nm, which endowed ZPR NPs with a photothermal conversion efficiency as high as 45.8% for photothermal therapy (PTT). Moreover, owing to the abundant surface oxygen defects, ZPR NPs can serve as a category of high-performance nano-sonosensitizer based on the strengthened separation of electron (e^-)/hole (h⁺) pairs from the energy band under external ultrasound (US) activation. More importantly, cytotoxic reactive oxygen species (ROS) generated from sonodynamic therapy (SDT) can effectively induce immunogenic cell death (ICD), which is regarded to be significant to boost systemic anti-tumor immunity for rendering a complete tumor eradication post-treatment. In vivo experiments on tumor xenografts demonstrated the high therapeutic efficacy upon photothermal-augmented sonodynamic therapy, with the aid of photoacoustic (PA) imaging navigation. Remarkably, the level of inflammatory cytokines, including type I interferon (IFN), tumor necrosis factor α (TNF-α) as well as interleukin (IL-6) were systemically upgraded after NIR-II/US irradiation, verifying the promotion of immunogenicity. Taken together, this study delivers useful insights for extending the applications of zirconia as promising translational medicine for tumor theranostics in the near future.

Hypoxia modulation by dual-drug nanoparticles for enhanced synergistic sonodynamic and starvation therapy

BACKGROUND

Sonodynamic therapy (SDT) is an emerging non-invasive therapeutic technique. SDT-based cancer therapy strategies are presently underway, and it may be perceived as a promising approach to improve the efficiency of anti-cancer treatment. In this work, multifunctional theranostic nanoparticles (NPs) were synthesized for synergistic starvation therapy and SDT by loading glucose oxidase (GOx, termed G) and 5,10,15,20-tetrakis (4-chlorophenyl) porphyrin) Cl (T (p-Cl) PPMnCl, termed PMnC) in Poly (lactic-co-glycolic) acid (PLGA) NPs (designated as MG@P NPs).

RESULTS

On account of the peroxidase-like activity of PMnC, MG@P NPs can catalyze hydrogen peroxide (H2O2) in tumor regions to produce oxygen (O2), thus enhancing synergistic therapeutic effects by accelerating the decomposition of glucose and promoting the production of cytotoxic singlet oxygen (1O2) induced by ultrasound (US) irradiation. Furthermore, the NPs can also serve as excellent photoacoustic (PA)/magnetic resonance (MR) imaging contrast agents, effectuating imaging-guided cancer treatment.

CONCLUSION

Multifunctional MG@P NPs can effectuate the synergistic amplification effect of cancer starvation therapy and SDT by hypoxia modulation, and act as contrast agents to enhance MR/PA dual-modal imaging. Consequently, MG@P NPs might be a promising nano-platform for highly efficient cancer theranostics.

Hollow carbon-based nanosystem for photoacoustic imaging-guided hydrogenothermal therapy in the second near-infrared window

Compared with the near-infrared-I spectral window (NIR-I, 650-950 nm), a newly developed imaging and treatment window with a 1000-1700 nm range (defined as the NIR-II bio-window) has attracted much attention owing to its higher spatiotemporal resolution, increased tissue penetration depth and therapeutic efficacy. Herein, we designed a nanotheranostic platform (HC-AB NPs) via loading ammonia borane (AB) into hollow carbon nanoparticles (HCs) for NIR-II photoacoustic (PA) imaging-guided NIR-II hydrogenothermal therapy. Importantly, by exploiting the characteristics of beta zeolite as a hard template and a template-carbonization-corrosion process, the prepared HCs have excellent NIR-II absorption performance and AB loading capacity. With the high biocompatibility of HC-AB NPs, an efficient synergistic anti-tumor strategy has been achieved via high intratumoural accumulation and acid-stimulated H2 release as well as PA-guided precise NIR-II photothermal therapy. The HC-AB NPs as a promising nanotheranostic platform opens a new avenue for high-efficacy NIR-II hydrogenothermal therapy.

A cascaded enzyme-loaded Fe-hemoporfin framework for synergistic sonodynamic-starvation therapy of tumors

Enzyme-loaded nanosystems with multimodal therapeutic functions have received increasing attention in the treatment of malignant tumors. Herein, we designed and prepared cascaded dual-enzyme-augmented Fe-hemoporfin framework nanosonosensitizers for synergistic sonodynamic-starvation therapy of tumors. Amorphous Fe-hemoporfin frameworks (FeHF) with an average size of ∼85 nm were synthesized by assembling the clinical drug hemoporfin with Fe³⁺ ions. Then, FeHF was used to load dual enzymes (glucose oxidase (GOx) and catalase (CAT)) and modified by PEGylated folic acid-conjugated lipids. The dual-enzyme loaded FeHF (FeHF-GOx/CAT) exhibited higher efficiency not only for glucose depletion but also for ultrasound (US)-triggered ¹O₂ generation than that of pure FeHF, resulting from the cascaded catalytic reaction from the dual-enzyme system. As observed by magnetic resonance imaging, the intravenously injected FeHF-GOx/CAT was accumulated within tumors. The FeHF-GOx/CAT + US exhibited the highest inhibition effect compared to the FeHF-CAT + US (only SDT) or FeHF-GOx/CAT (only starvation therapy), due to the synergistic effects of SDT and starvation therapy. Therefore, the cascaded dual-enzyme loading strategy can increase the SDT efficiency of FeHF, which may guide further works in the development of efficient nanosonosensitizers.

Targeted sonodynamic destruction of glioblastoma cells using antibody-titanium dioxide nanoparticle conjugates

Aim: We present data on sonodynamic therapy (SDT) against glioblastoma cells utilizing titanium dioxide (TiO₂) nanoparticles conjugated to anti-EGFR antibody. Materials & methods: TiO₂ nanoparticles were bound to anti-EGFR antibody to form antibody-nanoparticle conjugates (ANCs), then characterized by x-ray photoelectron spectroscopy and transmission electron microscopy. Cells underwent ultrasound and assessment on viability, reactive oxygen species and apoptosis were performed. Results: X-ray photoelectron spectroscopy analysis revealed the formation of an ANC. Transmission electron microscopy showed internalization of the ANCs by glioblastoma cells. With SDT, cell viabilities were reduced in the presence of ANCs, reactive oxygen species production was formed, but minimal effect on apoptosis was seen. Conclusion: For the first time, an ANC can be used with SDT to kill glioblastoma cells.

Multi-Responsive Bottlebrush-Like Unimolecules Self-Assembled Nano-Riceball for Synergistic Sono-Chemotherapy

Improved drug loading content, bioavailability, and controlled release in targeted tissue have been major bottlenecks in the design of precision nanomedicine. Herein, a tumor-specific and multiple-stimuli responsive nano-riceball is proposed and validated for enhanced sono-chemotherapy. The nano-riceball (NGR@DDP) possesses a well-designed core-shell structure, formed by an inner core assembly that contains ultrasound/H₂ O₂ responsive bottlebrush-like unimolecular dextran-POEGMA₉ -b-PMTEMA₂₂ (DOS) with co-loaded doxorubicin and Purpurin 18. This inner core of NGR@DDP is further buried by a "striffen" of NGR (Asn-Gly-Arg)-modified RBC-membrane derived from CRISPR-engineered mice. As a result, nano-riceball NGR@DDP is featured with high drug stuffing content (30.3 wt%), low critical micelle concentration (5.93 µg mL^-1 ), and intelligent exogenous ultrasound/endogenous H₂ O₂ stimuli-triggered precise drug release at tumor site. Under fluorescence/photoacoustic imaging guidance, combined sonodynamic therapy and chemotherapy exhibit excellent synergistic effect, and dramatically inhibit the growth of orthotopic HepG2 hepatocellular carcinoma with negligible side effects. This nano-riceball strategy provides a facile way to achieve function hybridization for personalized nanomedicine.

Graphene Quantum Dots with Pyrrole N and Pyridine N: Superior Reactive Oxygen Species Generation Efficiency for Metal-Free Sonodynamic Tumor Therapy

Those responsible for the development of sonosensitizers are faced with a dilemma between high sonosensitization efficacy and good biosecurity that limited the development of sonodynamic therapy (SDT). Herein, inspired by the intriguing therapeutic features of SDT and the potential catalytic activity of graphene quantum dots, the potential of N-doped graphene quantum dots (N-GQDs) to act as a sonosensitizer is demonstrated. The superior sonosensitization effect of N-GQDs is believed to be three to five times higher than that of traditional sonosensitizers (such as porphyrin, porphyrin Mn, porphyrin Zn, TiO₂ , etc.). More importantly, the sonochemical mechanism of N-GQDs is revealed. Pyrrole N and pyridine N are believed to form catalytic centers in sonochemical processing of N-GQDs. This knowledge is important from the perspective of understanding the structure-dependent SDT enhancement of carbon nanostructure. Moreover, N-GQDs modified by folic acid (FA-N-GQDs) show a high marker rate for tumor cells (greater than 96%). Both in vitro and in vivo therapeutic results have exhibited high tumor inhibition efficiency (greater than 90%) of FA-N-GQDs as sonosensitizers while the oxidative stress response of tumor cells is activated through the PEX pathway and induced apoptosis via the p53 pathway.

Current Advances in Black Phosphorus-Based Drug Delivery Systems for Cancer Therapy

Cancer has been one of the major threats to the lives of human beings for centuries. Traditional therapy is more or less faced with certain defects, such as poor targeting, easy degradation, high side effects, etc. Therefore, in order to improve the treatment efficiency of drugs, an intelligent drug delivery system (DDS) is considered as a promising solution strategy. Due to their special structure and large specific surface area, 2D materials are considered to be a good platform for drug delivery. Black phosphorus (BP), as a new star of the 2D family, is recommended to have the potential to construct DDS by virtue of its outstanding photothermal therapy (PTT), photodynamic therapy (PDT), and biodegradable properties. This tutorial review is intended to provide an introduction of the current advances in BP-based DDSs for cancer therapy, which covers topics from its construction, classified by the types of platforms, to the stimuli-responsive controlled drug release. Moreover, their cancer therapy applications including mono-, bi-, and multi-modal synergistic cancer therapy as well as the research of biocompatibility are also discussed. Finally, the current status and future prospects of BP-based DDSs for cancer therapy are summarized.

Polypyrrole-Coated Mesoporous TiO2 Nanocomposites Simultaneously Loading DOX and Aspirin Prodrugs for a Synergistic Theranostic and Anti-Inflammatory Effect

Although a number of therapeutic strategies have been applied in cancer therapy, treatment for cancer metastasis is challenging due to unsatisfactory cure rate and easy cancer recurrence. In our work, nanocomposites (NCs) based on polypyrrole-coated mesoporous TiO₂ with a suitable size are prepared through a modified soft-templating strategy, which integrates double prodrugs (doxorubicin (DOX) prodrug and aspirin prodrug) with superior drug loading capacity. Under external stimulation of near-infrared (NIR) and ultrasound (US), the prepared nanocomposites have an excellent photothermal conversion efficiency (over 50.8%) and a satisfactory sonodynamic therapeutic effect, and simultaneous prodrug activation and drug release occur rapidly under external stimulation. Through intravenous injection, the tumor area can be clearly seen through thermal imaging, benefiting from the enhanced permeability and retention (EPR) effect. Through synergistic therapy, cancer cell toxicity and the tumor inhibition effect are significantly enhanced. Moreover, downregulated inflammatory factors also reduce the risk of cancer recurrence. In general, the designed NCs provide a potential alternative for synergistic therapy as well as downregulation of inflammatory cytokines.

Dual ultrasound-activatable nanodroplets for highly-penetrative and efficient ovarian cancer theranostics

The selective delivery and deep intertumoral penetration of nanosensitizers remain challenging in the fabrication of sonodynamic therapy (SDT) platforms. In this work, we rationally constructed dual ultrasound (US)-activatable nanodroplets (NDs)/nanoliposomes/nanosensitizers with perfluoropentane (PFP) in the core, hematoporphyrin monomethyl ether (HMME) in the phospholipid shell and folate (FA)-conjugated to the surface (collectively termed FA-H@NDs). We aimed to validate the feasibility of these FA-H@NDs for FA receptor (FR)-overexpressed ovarian cancer theranostics. The ND formulations were based on PFP that can undergo acoustic droplet vaporization (ADV) when exposed to US irradiation. The ADV phenomenon disrupts the adjacent vasculature, and the resistance to drug diffusion within the tumor can be decreased, enabling nanosensitizers to more deeply penetrate into the inner tissue far from the intertumoral vasculature. These FA-H@NDs assisted by US irradiation can also induce the production of excess reactive oxygen species (ROS) and consequently trigger tumor cell/tissue apoptosis and necrosis. Furthermore, this therapeutic process can be guided and monitored by US/photoacoustic (PA) dual-modal imaging. This work established a new paradigm for highly efficient ovarian cancer theranostics based on the rational utilization of dual US-activatable NDs.

An in vitro study on the antitumor effect of sonodynamic therapy using sinoporphyrin sodium on human glioblastoma cells

Sonodynamic therapy (SDT) is a promising modality for cancer treatment. Sinoporphyrin sodium (DVDMS), purified from Photofrin II, shows great potential in SDT evidenced by growing studies. The purpose of the current study was to investigate the antitumor effect of SDT combined with DVDMS on human glioblastoma (U87 MG) cell line in vitro. The cellular uptake of DVDMS was investigated by confocal microscopy and IVIS spectrum imaging system. In addition, DVDMS toxicity and anti-tumor effect of SDT were assessed by flow cytometry. The generation of intracellular reactive oxygen species (ROS) was determined using DCFH-DA staining. Simultaneously, fluorescence microscopy was performed to access the destabilization of mitochondrial membrane potential (MMP). The results showed that DVDMS could easily enter the cells and accumulated in the cytoplasm, especially the mitochondria. And the intracellular DVDMS increased with incubation time or concentrations. The results also showed remarkable cytotoxicity of DVDMS-mediated SDT (center frequency: 0.970 MHz; peak-rarefactional pressure: 0.52-MPa; acoustic power: 0.32 W; pulse repetition frequency: 1 Hz; duty cycle: 1-30%; duration: 3 min) on U87 MG cells, while DVDMS alone was non-toxic to the cells. In comparison with the control group, the SDT-treated group showed significant generation of intracellular ROS and loss of MMP at 1 h post-treatment. These results indicated that DVDMS-mediated SDT could induce great cytotoxicity in U87 MG cells via the production of ROS and showed potentials in the treatment for glioblastoma.

Recent advances in innovative strategies for enhanced cancer photodynamic therapy

Photodynamic therapy (PDT), a non-invasive therapeutic modality, has received increasing attention owing to its high selectivity and limited side effects. Although significant clinical research progress has been made in PDT, the breadth and depth of its clinical application have not been fully realized due to the limitations such as inadequate light penetration depth, non-targeting photosensitizers (PSs), and tumor hypoxia. Consequently, numerous investigations put their emphasis on innovative strategies to overcome the aforementioned limitations and enhance the therapeutic effect of PDT. Herein, up-to-date advances in these innovative methods for PDT are summarized by introducing the design of PS systems, their working mechanisms and application examples. In addition, current challenges of these innovative strategies for clinical application, and future perspectives on further improvement of PDT are also discussed.

Solvothermal synthesis of Nb-doped TiO2 nanoparticles with enhanced sonodynamic effects for destroying tumors

Titania (TiO₂) nanomaterials have been proved to be biocompatible sonosensitizers for sonodynamic therapy (SDT) of various cancer cells, while they suffer from weak sonodynamic effects due to fast combination of excited carriers. In this work, to improve the therapeutic efficiency, we prepared PEGylated Nb-doped TiO₂ (TiO_2−x:Nb) nanoparticles by a simple solvothermal method and a subsequent surface modification process. The TiO_2−x:Nb nanoparticles exhibited an average size of 11 nm and a polydisperse index of 0.12. The Nb doping had no obvious effect on the phase of TiO₂ matrixes but released electrons to the conduction band of TiO₂, resulting in high concentrations of deficiencies. As a result, the TiO_2−x:Nb nanoparticles exhibited a higher efficiency of singlet oxygen (¹O₂) generation than that of pure TiO₂ nanoparticles upon ultrasound irradiation. Importantly, the TiO_2−x:Nb nanoparticles had high biocompatibility similar to pure TiO₂ nanoparticles, while they could efficiently produce cytotoxic ¹O₂ to destroy cancer cells in vitro in comparison to the partially destroyed cancer cells by pure TiO₂ nanoparticles upon ultrasound irradiation. More importantly, the TiO_2−x:Nb nanoparticles displayed obvious tumor cellular injury in tumor-bearing mice in vivo through high SDT effects. Therefore, the synthesized PEGylated TiO_2−x:Nb nanoparticles in this study exhibited higher therapeutic effects of SDT than that of the pure TiO₂ nanoparticles, and the doping strategy would provide some insights for tuning traditional weak sonosensitizers into efficient ones.

TiO_2−x:Nb nanoparticles displayed obvious tumor cellular injury in tumor-bearing mice in vivo through high SDT effect.

K. PK, Lee J, Kim CH, You DG, Park JH. Recent advances in nanomaterial-based augmented sonodynamic therapy of cancer

This review focuses on recent advances in augmented sonodynamic therapy (SDT) using engineered nanomaterials, and the mechanism of SDT for discussing future perspectives.

Synthesis and ultrasound mediated antibacterial activity of ferrocene-triazole-porphyrin derivative

The [3 + 2]-cycloaddition reaction of various azides with ferrocenylmethylpropargyl ester in the presence of copper (I) salt lead to the formation of ferrocenyl-containing derivatives, including porphyrin, which exhibit pronounced cytotoxicity against Escherichia coli under ultrasound irradiation.

Metalloporphyrins in Medicine: From History to Recent Trends

The history of metalloporphyrins dates back more than 200 years ago. Metalloporphyrins are excellent catalysts, capable of forming supramolecular systems, participate in oxygen photosynthesis, transport, and used as contrast agents or superoxide dismutase mimetics. Today, metalloporphyrins represent complexes of conjugated π-electron system and metals from the entire periodic system. However, the effect of these compounds on living systems has not been fully understood, and researchers are exploring the properties of metalloporphyrins thereby extending their further application. This review provides an overview of the variety of metalloporphyrins that are currently used in different medicine fields and how metalloporphyrins became the subject of scientists' interest. Currently, metalloporphyrins utilization has expanded significantly, which gave us an opprotunuty to summarize recent progress in metalloporphyrins derivatives and prospects of their application in the treatment and diagnosis of different diseases.

Molybdenum-based hetero-nanocomposites for cancer therapy, diagnosis and biosensing application: Current advancement and future breakthroughs

In recent years, there have been significant advancements in the nanotechnology for cancer therapy. Even though molybdenum disulphide (MoS2)-based nanocomposites demonstrated extensive applications in biosensing, bioimaging, phototherapy, the review article focusing on MoS2 nanocomposite platform has not been accounted for yet. The review summarizes recent strategies on design and fabrication of MoS2-based nanocomposites and their modulated properties in cancer treatment. The review also discussed several therapeutic strategies (photothermal, photodynamic, immunotherapy, gene therapy and chemotherapy) and their combinations for efficient cancer therapy along with certain case studies. The review also inculcates various diagnostic techniques viz. magnetic resonance imaging, computed tomography, photoacoustic imaging and fluorescence imaging for diagnosis of cancer.

Sonodynamic therapy in combination with photodynamic therapy shows enhanced long-term cure of brain tumor

This article presents the construction of a multimodality platform that can be used for efficient destruction of brain tumor by a combination of photodynamic and sonodynamic therapy. For in vivo studies, U87 patient-derived xenograft tumors were implanted subcutaneously in SCID mice. For the first time, it has been shown that the cell-death mechanism by both treatment modalities follows two different pathways. For example, exposing the U87 cells after 24 h incubation with HPPH [3-(1'-hexyloxy)ethyl-3-devinyl-pyropheophorbide-a) by ultrasound participate in an electron-transfer process with the surrounding biological substrates to form radicals and radical ions (Type I reaction); whereas in photodynamic therapy, the tumor destruction is mainly caused by highly reactive singlet oxygen (Type II reaction). The combination of photodynamic therapy and sonodynamic therapy both in vitro and in vivo have shown an improved cell kill/tumor response, that could be attributed to an additive and/or synergetic effect(s). Our results also indicate that the delivery of the HPPH to tumors can further be enhanced by using cationic polyacrylamide nanoparticles as a delivery vehicle. Exposing the nano-formulation with ultrasound also triggered the release of photosensitizer. The combination of photodynamic therapy and sonodynamic therapy strongly affects tumor vasculature as determined by dynamic contrast enhanced imaging using HSA-Gd(III)DTPA.

Curcumin-gold-polyethylene glycol nanoparticles as a nanosensitizer for photothermal and sonodynamic therapies: In vitro and animal model studies

Photothermal and ultrasound therapies are novel non-invasive strategies for tumor treatment which are equipped with a photosensitizer and sonosensitizer subsequent activation by laser irradiation and ultrasound exposure. In this study, curcumin-gold-polyethylene glycol nanoparticles (Cur-Au NPs-PEG) were synthesized, and the dual role in photothermal (PTT) and sonodynamic (SDT) therapies of melanoma cancer was evaluated. The toxicity effect of Cur-Au NPs-PEG against a mouse malignant melanoma cell line C540 (B16/F10) was firstly inspected in vitro. Cur-Au NPs-PEG provided a hyperthermal microenvironment and generated reactive oxygen species upon PTT and STD, respectively, with representing synergism effects. Studies in vivo in a tumor-bearing animal also demonstrate the superiority of PTT and SDT in destroying melanoma tumor.

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

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

Recent Advances in Nanomaterial-Assisted Combinational Sonodynamic Cancer Therapy

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

Sonodynamic therapy-derived multimodal synergistic cancer therapy

Sonodynamic therapy (SDT) represents a promising modality that provides the possibility of non-invasively eliminating solid tumors in a site-directed manner. In light of the complexity and heterogeneity of tumors, more and more studies are attempting to combine SDT with other therapeutic methods so as to achieve better tumor treatment effect, which sheds new light on the potential of SDT-based synergistic therapeutics. Herein, the representative studies of SDT-instructed multimodal synergistic cancer therapy are comprehensively presented, such as sono-chemotherapy, sono-radiotherapy, sono-immunotherapy, and sono-chemodynamic therapy, etc., and their incorporate mechanisms are discussed in detail. The current challenges and future prospects to promote the advanced development of SDT-based nanomedicines in this burgeoning research field are highlighted. It is believed that such an emerging synergistic therapeutic modality based on SDT will play a more significant role in the field of tumor precision treatment medicine.

Protamine sulphate coated poly (lactide-co-glycolide) nanoparticles of MUC-1 peptide improved cellular uptake and cytokine release in mouse antigen presenting cells

AIM

MUC-1-peptide (M-1-pep) loaded poly (lactide-co-glycolide) nanoparticles were coated with protamine sulphate (PS), M-1-pep-PS-P-NPs for targeting antigen presenting cells (APCs) to evoke cytokine release.

METHODS AND RESULTS

M-1-pep-PS-P-NPs were tailored by emulsion-diffusion evaporation method and characterised in vitro under a set of rigorous parameters. The average particle size and zeta potential of optimised M-1-pep-PS-P-B-NPs was measured to be 132.21 ± 30.71 nm and 6.29 ± 0.71 mV, significantly (p < 0.01) higher than 71.24 ± 17.76-nm and -43.41 ± 3.37 mV of M-1-pep-P-NPs. Further, 50-μg/ml concentration of M-1-pep-PS-P-B-NPs displayed 82.4% cellular uptake in RAW 264.7 cells calculated in setting of fluorescence intensity significantly (p < 0.05) elevated than 63.1% of M-1-pep-P-NPs. Consistent to quantitative results, M-1-pep-PS-P-B-NPs also confirmed advanced cellular uptake (CU) in RAW 264.7 cells in contrast to M-1-pep-P-NPs suppose to be through multiple mechanisms including phagocytosis and clathrin mediated endocytosis.

CONCLUSION

M-1-pep-PS-P-B-NPs must be evaluated in vivo through inhalation route of administration for antitumor prospective in lung cancer xenograft model.

Erlotinib-Loaded Poly(ε-Caprolactone) Nanocapsules Improve In Vitro Cytotoxicity and Anticlonogenic Effects on Human A549 Lung Cancer Cells

Lung cancer is the most frequent type of cancer and the leading cause of cancer-related mortality worldwide. This study aimed to develop erlotinib (ELB)-loaded poly(ε-caprolactone) nanocapsules (NC_ELB) and evaluated their in vitro cytotoxicity in A549 cells. The formulation was characterized in relation to hydrodynamic diameter (171 nm), polydispersity index (0.076), zeta potential (- 8 mV), drug content (0.5 mg^.mL^-1), encapsulation efficiency (99%), and pH (6.0). NC_ELB presented higher cytotoxicity than ELB in solution against A549 cells in the MTT and LIVE/DEAD cell viability assays after 24 h of treatment. The main mechanism of cytotoxicity of NC_ELB was the induction of apoptosis in A549 cells. Further, a significant decrease in A549 colony formation was verified after NC_ELB treatment in comparison with the unencapsulated drug treatment. The reduction in clonogenic capacity is very relevant as it can reduce the risk of tumor recurrence and metastasis. In conclusion, erlotinib-loaded PCL nanocapsules are promising nanoparticles carriers to increase the efficacy of ELB in lung cancer treatment.

Curcumin-Loaded Poly(L-lactide-co-glycolide) Microbubble-Mediated Sono-photodynamic Therapy in Liver Cancer Cells

Sono-photodynamic therapy (SPDT) activates the same photo-/sonosensitizer and exerts more marked antitumor effects than sonodynamic therapy or photodynamic therapy. We aimed to explore the utilization of curcumin (CUR)-loaded poly(L-lactide-co-glycolide) microbubble (MB)-mediated SPDT (CUR-PLGA-MB-SPDT) in HepG2 liver cancer cells. The cytotoxicity and intracellular accumulation of CUR were determined. We used 40 µM CUR as the photo-/sonosensitizer for 3 h. In a comparison of CUR-SDT or CUR-PDT, HepG2 cell viability decreased and apoptotic rate increased in CUR-SPDT. The CUR-PLGA MBs had round spheres with smooth surfaces and an average size of 3.7 µm. In CUR-PLGA MBs, drug entrapment efficiency and drug-loading capacity were 74.29 ± 2.60% and 17.14 ± 0.60%, respectively. CUR-loaded PLGA MBs (CUR-PLGA MBs) had good biocompatibility with normal L02 cells and were almost non-cytotoxic to HepG2 cells. Among CUR-SDT, CUR-PDT, CUR-SPDT or CUR-PLGA-MB-SDT, the cell CUR-PLGA-MB-SPDT had the lowest viability. Transmission electron microscopy revealed pyroptosis and apoptosis in the CUR-PLGA-MB-SPDT group; the potential mechanism was related to the mitochondrial membrane potential loss and increased production of intracellular reactive oxygen species. These findings suggested that CUR-PLGA-MB-SPDT may be a promising treatment for liver cancer.

Biocompatible Fe-Hematoporphyrin coordination nanoplatforms with efficient sonodynamic-chemo effects on deep-seated tumors

Sonodynamic therapy (SDT) utilizing semiconductors or organic sonosensitizers has attracted increasing attention as a noninvasive treatment for deep-seated tumors, but its practical applications are still limited due to unsatisfactory therapeutical effects. To address the issue, we reported a metal-organic nanosonosensitizer by assembling clinical drug hematoporphyrin monomethyl ether (HMME) with Fe(III) ions through covalently coordination. The Fe-HMME coordination particles (FeCPs) had the average size of ~70 nm, and they were surface-modified with phospholipids to confer high hydrophilicity and stability. Upon ultrasound irradiation, they efficiently produced ¹O₂ to destroy cancer cells coated without or with tissue-barriers (1-3 cm). Importantly, the porous structure of FeCPs facilitated high loading capacity (31.3%) of anticancer drug doxorubicin (DOX), and the DOX@FeCPs exhibited pH-sensitive and ultrasound-enhanced releasing behavior that was favorable to the acidic microenvironment of tumors. When the lipids-coated FeCPs were intravenously injected into tumor-bearing mouse, they could passively accumulate within tumors, leading to the magnetic resonance imaging of tumors. Importantly, as deep-seated tumor model, tumors covered with barrier were exposed to ultrasound and thereafter their growth was significantly inhibited by SDT of FeCPs. The inhibition effects could be further enhanced by DOX@FeCPs due to the SDT-chemo combined therapy. Therefore, the DOX@FeCPs have achieved good therapeutical performances on deep-seated tumor and would supply some insights on the design of other metal-organic nanoplatforms.

Piezocatalytic Tumor Therapy by Ultrasound-Triggered and BaTiO3 -Mediated Piezoelectricity

Ultrasound theranostics features non-invasiveness, minor energy attenuation, and high tissue-penetrating capability, and is playing ever-important roles in the diagnosis and therapy of diseases in clinics. Herein, ultrasound is employed as a microscopic pressure resource to generate reactive oxygen species (ROS) for piezocatalytic tumor therapy under catalytic mediation by piezoelectric tetragonal BaTiO₃ (T-BTO). Under the ultrasonic vibration, the electrons and holes are unpaired and they are separated by the piezoelectricity, resulting in the establishment of a strong built-in electric field, which subsequently catalyzes the generation of ROS such as toxic hydroxyl (^• OH) and superoxide radicals (^• O₂ ^- ) in situ for tumor eradication. This modality shows intriguing advantages over typical sonoluminescence-activated sonodynamic therapy, such as more stable sensitizers and dynamical control of redox reaction outcomes. Furthermore, according to the finite element modeling simulation, the built-in electric field is capable of modulating the band alignment to make the toxic ROS generation energetically favorable. Both detailed in vitro cellular level evaluation and in vivo tumor xenograft assessment have demonstrated that an injectable T-BTO-nanoparticles-embedded thermosensitive hydrogel will substantially induce ultrasound irradiation-triggered cytotoxicity and piezocatalytic tumor eradication, accompanied by high therapeutic biosafety in vivo.

An in vitro study on sonodynamic treatment of human colon cancer cells using sinoporphyrin sodium as sonosensitizer

BACKGROUND

Colorectal cancer is the third leading cause of cancer-related deaths worldwide. Sonodynamic therapy (SDT) is an emerging cancer therapy, and in contrast to photodynamic therapy, could non-invasively reach deep-seated tissues and locally activates a sonosensitizer preferentially accumulated in the tumor area to produce cytotoxicity effects. In comparison with traditional treatments, SDT may serve as an alternative strategy for human colon cancer treatment. Here, we investigated the sonodynamic effect using sinoporphyrin sodium (DVDMS) as a novel sonosensitizer on human colon cancer cells in vitro.

RESULTS

The absorption spectra of DVDMS revealed maximum absorption at 363 nm wavelength and emission peak at 635 nm. Confocal microscopy images revealed the DVDMS was primarily localized in the cytoplasm, while no evident signal was detected within the nuclei. Flow cytometry analysis showed rapid intracellular uptake of DVDMS by two types of human colon cancer cells (HCT116 and RKO). Cell viability of HCT116 was tolerant with the concentration of DVDMS up to 20 µg/mL, while the case of RKO was 5 µg/mL. In comparison with the control group, the SDT-treated groups of these two types of human colon cancer cells showed significant increase in cellular apoptosis and necrosis ratio. Increased intracellular reactive oxygen species (ROS) production was detected, indicating the involvement of ROS in mediating SDT effects.

CONCLUSION

DVDMS results an effective sonosensitizer for the ultrasound-mediated cancer cell killing, and its anticancer effect seems to rely on its ability to produce ROS under ultrasound exposure.

Shock wave impact on the viability of MDA-MB-231 cells

Shock waves are gaining interests in biological and medical applications. In this work, we investigated the mechanical characteristics of shock waves that affect cell viability. In vitro testing was conducted using the metastatic breast epithelial cell line MDA-MB-231. Shock waves were generated using a high-power pulse laser. Two different coating materials and different laser energy levels were used to vary the peak pressure, decay time, and the strength of subsequent peaks of the shock waves. Within the testing capability of the current study, it is shown that shock waves with a higher impulse led to lower cell viability, a higher detached cell ratio, and a higher cell death ratio, while shock waves with the same peak pressure could lead to different levels of cell damage. The results also showed that the detached cells had a higher cell death ratio compared to the attached cells. Moreover, a critical shock impulse of 5 Pa·s was found to cause the cell death ratio of the detached cells to exceed 50%. This work has demonstrated that, within the testing range shown here, the impulse, rather than the peak pressure, is the governing shock wave parameter for the damage of MDA-MB-231 breast cancer cells. The result suggests that a lower-pressure shock wave with a longer duration, or multiple sequential low amplitude shock waves can be applied over a duration shorter than the fundamental response period of the cells to achieve the same impact as shock waves with a high peak pressure but a short duration. The finding that cell viability is better correlated with shock impulse rather than peak pressure has potential significant implications on how shock waves should be tailored for cancer treatments, enhanced drug delivery, and diagnostic techniques to maximize efficacy while minimizing potential side effects.