Design and application of inorganic nanoparticles for sonodynamic cancer therapy

Zirconia-Platinum Nanohybrids for Ultrasound-Activated Sonodynamic-Thermodynamic Bimodal Therapy by Inducing Intense Intracellular Oxidative Stress

The therapeutic exploration of nano-zirconia semiconductor largely remains untouched in the field of fundamental science to date. Here, a robust nano-sonosensitizer of ZrO_{2- x} @Pt is strategically formulated by in situ growth of Pt nanocrystal onto the surface of oxygen-deficient ZrO_{2- x} . Compared to 3.09 eV of nano-ZrO_{2- x} , the bandgap of ZrO_{2- x} @Pt Schottky junction is narrowed down to 2.74 eV. The band bending and bandgap narrowing enables an enhanced e^- /h⁺ separation in the presence of aPt electron sink, which facilitates a high yield of singlet oxygen (¹ O₂ ) and hydroxyl radicals (·OH) under ultrasound (US) irradiation. Moreover, nanozyme Pt with catalase-mimic activity can promote ¹ O₂  generation by relieving the hypoxic tumor microenvironment. Upon further modification of 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (AIPH), US-stimulated local thermal shock can disintegrate AIPH to create cytotoxic alkyl radicals (^• R). US-triggered reactive oxygen species generation and hyperthermia-induced alkyl radical production lead to severe and irreversible tumor cell death. Such combinatorial sonodynamic-thermodynamic therapy benefits the tumor eradication and metastasis inhibition at the animal level, with the aid of immunogenetic cell death and immune checkpoint blockade. Taken together, this proof-of-concept paradigm expands the medical use of nano-zirconia and provides useful insights for its therapeutic perspectives.

Platinum-Titania Schottky Junction as Nanosonosensitizer, Glucose Scavenger, and Tumor Microenvironment-Modulator for Promoted Cancer Treatment

To date, the construction of heterogeneous interfaces between sonosensitizers and other semiconductors or noble metals has aroused increasing attention, owing to an enhanced interface charge transfer, augmented spin-flip, and attenuated activation energy of oxygen. Here, a smart therapeutic nanoplatform is constructed by surface immobilization of glucose oxidase (GOx) onto a TiO₂@Pt Schottky junction. The sonodynamic therapy (SDT) and starvation therapy (ST) mediated by TiO₂@Pt/GOx (TPG) promote systemic tumor suppression upon hypoxia alleviation in tumor microenvironment. The band gap of TiO₂@Pt is outstandingly decreased to 2.9 eV, in contrast to that of pristine TiO₂. The energy structure optimization enables a more rapid generation of singlet oxygen (¹O₂) and hydroxyl radicals (^•OH) by TiO₂@Pt under ultrasound irradiation, resulting from an enhanced separation of hole-electron pair for redox utilization. The tumorous reactive oxygen species (ROS) accumulation and GOx-mediated glucose depletion facilitate oxidative damage and energy exhaustion of cancer cells, both of which can be tremendously amplified by Pt-catalyzed oxygen self-supply. Importantly, the combinatorial therapy triggers intense immunogenetic cell death, which favors a follow-up suppression of distant tumor and metastasis by evoking antitumor immunity. Collectively, this proof-of-concept paradigm provides an insightful strategy for highly efficient SDT/ST, which possesses good clinical potential for tackling cancer.

Simultaneous chemotherapy/sonodynamic therapy of the melanoma cancer cells using a gold-paclitaxel nanostructure

Nanodrug delivery systems are novel strategies for tumor treatment since delivery of chemotherapy drugs such as paclitaxel (PTX) is associated with substantial challenges due to its poor aqueous solubility. In addition, sonodynamic therapy (SDT) is a promising approach that can increase the uptake, accumulation, and dispersion of desirable amounts of the drugs by activating sonosensitizer and enhancing cell membrane permeability. Herein, gold-paclitaxel nanoparticles (Au-PTX NPs) were synthesized and characterized to evaluate the cytotoxicity toward C540 cancer cells in comparison of free PTX, AuNPs, and AuNPs+free PTX in the absence and presence of ultrasound radiation. Evidence shows that AuNPs have a median diameter size of 95.0 ± 15.4, while the size of Au-PTX NPs is roughly 219.7 ±  40.4 nm. Negative zeta-potential results indicate high stability and good dispersion of nanoparticles. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay results revealed that Au-PTX NPs increased the cytotoxicity compared to other treatment groups that ensure the great potential of AuNPs as a promising nano-carrier for PTX drug delivery. Moreover, the viability of C540 cells treated by Au-PTX NPs under ultrasound radiation was decreased significantly by generating more reactive oxygen species (ROS) upon STD, with representing synergism effects confirming the role of gold nanoparticles as an excellent sonosensitizer and the role of SDT as an adjunctive treatment method with chemotherapy.

Ultrasound Microbubbles Mediated Sonosensitizer and Antibody Co-delivery for Highly Efficient Synergistic Therapy on HER2-Positive Gastric Cancer

Trastuzumab combined with chemotherapy is the first-line treatment for advanced HER2-positive gastric cancer, but it still suffers from limited therapeutic efficiency and serious side effects, which are usually due to the poor delivery efficiency and the drug resistance of tumor cells to the chemotherapeutic drugs. Herein, a type of ultrasound microbubble for simultaneous delivery of sonosensitizers and therapeutic antibodies to achieve targeting combination of sonodynamic therapy and antibody therapy of HER2-positive gastric cancer was constructed from pyropheophorbide-lipid followed by trastuzumab conjugation (TP MBs). In vitro and in vivo studies showed that TP MBs had good biological safety, and their in vivo delivery can be monitored by ultrasound/fluorescence bimodal imaging. With ultrasound (US) located at the tumor area, TP MBs can be converted into nanoparticles (TP NPs) in situ by US-targeted microbubble destruction; plus the enhanced permeability and retention effects and the targeting effects of trastuzumab, the enrichment of sonosensitizers and antibodies in the tumor tissue can be greatly enhanced (∼2.1 times). When combined with ultrasound, TP MBs can not only increase the uptake of sonosensitizers in HER2-positive gastric cancer NCI-N87 cells but also efficiently generate singlet oxygen to greatly increase the killing effect on cells, obviously inhibiting the tumor growth in HER2-positive gastric cancer NCI-N87 cell models with a tumor inhibition rate up to 79.3%. Overall, TP MBs combined with US provided an efficient way for co-delivery of sonosensitizers and antibodies, greatly enhancing the synergistic therapeutic effect on HER2-positive gastric cancer while effectively reducing the side effects.

2D Piezoelectric Bi2 MoO6 Nanoribbons for GSH-Enhanced Sonodynamic Therapy

Reducing the scavenging capacity of reactive oxygen species (ROS) and elevating ROS production are two primary goals of developing novel sonosensitizers for sonodynamic therapy (SDT). Hence, ultrathin 2D Bi2 MoO6 -poly(ethylene glycol) nanoribbons (BMO NRs) are designed as piezoelectric sonosensitizers for glutathione (GSH)-enhanced SDT. In cancer cells, BMO NRs can consume endogenous GSH to disrupt redox homeostasis, and the GSH-activated BMO NRs (GBMO) exhibit an oxygen-deficient structure, which can promote the separation of electron-hole pairs, thereby enhancing the efficiency of ROS production in SDT. The ultrathin GBMO NRs are piezoelectric, in which ultrasonic waves introduce mechanical strain to the nanoribbons, resulting in piezoelectric polarization and band tilting, thus accelerating toxic ROS production. The as-synthesized BMO NRs enable excellent computed tomography imaging of tumors and significant tumor suppression in vitro and in vivo. A piezoelectric Bi2 MoO6 sonosensitizer-mediated two-step enhancement SDT process, which is activated by endogenous GSH and amplified by exogenous ultrasound, is proposed. This process not only provides new options for improving SDT but also broadens the application of 2D piezoelectric materials as sonosensitizers in SDT.

Enhancing Cancer Immunotherapeutic Efficacy with Sonotheranostic Strategies

Immunotherapy has revolutionized the modality for establishing a firm immune response and immunological memory. However, intrinsic limitations of conventional low responsive poor T cell infiltration and immune related adverse effects urge the coupling of cancer nanomedicines with immunotherapy for boosting antitumor response under ultrasound (US) sensitization to mimic dose-limiting toxicities for safe and effective therapy against advanced cancer. US is composed of high-frequency sound waves that mediate targeted spatiotemporal control over release and internalization of the drug. The unconventional US triggered immunogenic nanoengineered arena assists the limited immunogenic dose, limiting toxicities and efficacies. In this Review, we discuss current prospects of enhanced immunotherapy using nanomedicine under US. We highlight how nanotechnology designs and incorporates nanomedicines for the reprogramming of systematic immunity in the tumor microenvironment. We also emphasize the mechanical and biological potential of US, encompassing sonosensitizer activation for enhanced immunotherapeutic efficacies. Finally, the smartly converging combinational platform of US stimulated cancer nanomedicines for amending immunotherapy is summarized. This Review will widen scientists' ability to explore and understand the limiting factors for combating cancer in a precisely customized way.

Multifunctional Composite Nanosystems for Precise/Enhanced Sonodynamic Oxidative Tumor Treatment

Ultrasound-activated therapies have been regarded as the efficient strategy for tumor treatment, among which sonosensitizer-enabled sonodynamic oxidative tumor therapy features intrinsic advantages as compared to other exogenous trigger-activated dynamic therapies. Nanomedicine-based nanosonosensitizer design has been extensively explored for improving the therapeutic efficacy of sonodynamic therapy (SDT) of tumor. This review focuses on solving two specific issues, i.e., precise and enhanced sonodynamic oxidative tumor treatment, by rationally designing and engineering multifunctional composite nanosonosensitizers. This multifunctional design can augment the therapeutic efficacy of SDT against tumor by either improving the production of reactive oxygen species or inducing the synergistic effect of SDT-based combinatorial therapies. Especially, this multifunctional design is also capable of endowing the nanosonosensitizer with bioimaging functionality, which can effectively guide and monitor the therapeutic procedure of the introduced sonodynamic oxidative tumor treatment. The design principles, underlying material chemistry for constructing multifunctional composite nanosonosensitizers, intrinsic synergistic mechanism, and bioimaging guided/monitored precise SDT are summarized and discussed in detail with the most representative paradigms. Finally, the existing critical issues, available challenges, and potential future developments of this research area are also discussed for promoting the further clinical translations of these multifunctional composite nanosonosensitizers in SDT-based tumor treatment.

Pro-oxidant drug-loaded porphyrinic zirconium metal-organic-frameworks for cancer-specific sonodynamic therapy

Sonodynamic therapy, which utilizes ultrasound (US) to produce cytotoxic reactive oxygen species (ROS), can overcome the critical drawbacks of photodynamic therapy, such as limited tissue penetration depth. However, the development of sonosensitizers having superior sonodynamic effects and desirable biocompatibility remains a major challenge. In this study, nanoscale zirconium-based porphyrinic metal organic frameworks (MOFs) (PCN-222) were developed as safe and effective nanosonosensitizers. Polyethylene glycol (PEG)-coated PCN-222 (PEG-PCN) was loaded with a pro-oxidant drug, piperlongumine (PL), to enable tumor-specific chemo-photodynamic combination therapy. Both PEG-PCN and PL-incorporated PEG-PCN (PL-PEG-PCN) showed high colloidal stability in biological media. In addition, nanoscale PL-PEG-PCN was efficiently internalized by breast cancer cells, leading to substantially increased ROS generation under US exposure. The effective intracellular delivery of PL by PEG-PCN further elevated the level of intracellular ROS in breast cancer cells owing to the pro-oxidative activity of PL. Therefore, PL-PEG-PCN revealed significantly higher sonotoxicity than free PL and PEG-PCN. Owing to the cancer-specific apoptosis triggered by PL, PL-PEG-PCN showed cancer-selective cell death in breast cancer cells compared with normal fibroblast cells. This study demonstrates that pro-oxidant drug-loaded porphyrinic MOFs are biocompatible and effective sonosensitizers for cancer-targeted chemo-sonodynamic combination therapy.

Catalytically Active CoFe2O4 Nanoflowers for Augmented Sonodynamic and Chemodynamic Combination Therapy with Elicitation of Robust Immune Response

A hypoxic and acidic tumor microenvironment (TME) plays a significant role in cancer development through complex cellular signaling networks, and it is thus challenging to completely eradicate tumors via monotherapy. Here, PEGylated CoFe₂O₄ nanoflowers (CFP) with multiple enzymatic activities, serving as bioreactors responsive to TME cues, were synthesized via a typical solvothermal method for augmented sonodynamic therapy (SDT) and chemodynamic therapy (CDT) with elicitation of robust immune response. The CFP occupying multivalent elements (Co^2+/3+, Fe^2+/3+) exhibited strong Fenton-like and catalase-like activity. In another aspect, CFP itself is a brand-new sonosensitizer for high-performance SDT based on ultrasound-triggered electron (e^-)/hole (h⁺) pair separation from the energy band with promptness and high efficiency. With efficient enrichment in tumorous tissue as revealed by magnetic resonance imaging, CPF could generate ^•OH for CDT relying on Fenton-like reactions. Moreover, catalase-mimicking CFP could react with endogenous H₂O₂ to generate molecular oxygen, and high O₂ level may promote the production of ¹O₂ for SDT. What's more, the reactive oxygen species obtained from combined SDT/CDT could efficiently trigger immunogenic cell death through a synergistic therapy based on the elicitation of antitumor immunity with the aid of an immune checkpoint blockade for the sake of suppressing primary and distant tumors as well as lung metastasis. Taken together, this paradigm delivers useful insights for developing in-coming nanocomposites based on cobalt ferrite for cancer theranostics.

Sinoporphyrin sodium mediated sonodynamic therapy generates superoxide anions under a hypoxic environment

DVDMS-SDT induces G2/M arrest by superoxide anions.