Gas-stabilizing nanoparticles for ultrasound imaging and therapy of cancer

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

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

Ultrasound Trigger Ce-Based MOF Nanoenzyme For Efficient Thrombolytic Therapy

The inflammatory damage caused by thrombus formation and dissolution can increase the risk of thrombotic complications on top of cell death and organ dysfunction caused by thrombus itself. Therefore, a rapid and precise thrombolytic therapy strategy is in urgent need to effectively dissolve thrombus and resist oxidation simultaneously. In this study, Ce-UiO-66, a cerium-based metal-organic framework (Ce-MOF) with reactive oxygen species (ROS) scavenging properties, encapsulated by low-immunogenic mesenchymal stem cell membrane with inflammation-targeting properties, is used to construct a targeted nanomedicine Ce-UiO-CM. Ce-UiO-CM is applied in combination with external ultrasound stimulation for thrombolytic therapy in rat femoral artery. Ce-UiO-66 has abundant Ce (III)/Ce (IV) coupling sites that react with hydrogen peroxide (H2O2) to produce oxygen, exhibiting catalase (CAT) activity. The multi-cavity structure of Ce-UiO-66 can generate electron holes, and its pore channels can act as micro-reactors to further enhance its ROS scavenging capacity. Additionally, the porous structure of Ce-UiO-66 and the oxygen produced by its reaction with H2O2 may enhance the cavitation effects of ultrasound, thereby improving thrombolysis efficacy.

Application of Nanomaterial-Based Sonodynamic Therapy in Tumor Therapy

Sonodynamic therapy (SDT) has attracted significant attention in recent years as it is an innovative approach to tumor treatment. It involves the utilization of sound waves or ultrasound (US) to activate acoustic sensitizers, enabling targeted drug release for precise tumor treatment. This review aims to provide a comprehensive overview of SDT, encompassing its underlying principles and therapeutic mechanisms, the applications of nanomaterials, and potential synergies with combination therapies. The review begins by introducing the fundamental principle of SDT and delving into the intricate mechanisms through which it facilitates tumor treatment. A detailed analysis is presented, outlining how SDT effectively destroys tumor cells by modulating drug release mechanisms. Subsequently, this review explores the diverse range of nanomaterials utilized in SDT applications and highlights their specific contributions to enhancing treatment outcomes. Furthermore, the potential to combine SDT with other therapeutic modalities such as photothermal therapy (PTT) and chemotherapy is discussed. These combined approaches aim to synergistically improve therapeutic efficacy while mitigating side effects. In conclusion, SDT emerges as a promising frontier in tumor treatment that offers personalized and effective treatment options with the potential to revolutionize patient care. As research progresses, SDT is poised to play a pivotal role in shaping the future landscape of oncology by providing patients with a broader spectrum of efficacious and tailored treatment options.

Hydralazine loaded nanodroplets combined with ultrasound-targeted microbubble destruction to induce pyroptosis for tumor treatment

Pyroptosis, a novel type of programmed cell death (PCD), which provides a feasible therapeutic option for the treatment of tumors. However, due to the hypermethylation of the promoter, the critical protein Gasdermin E (GSDME) is lacking in the majority of cancer cells, which cannot start the pyroptosis process and leads to dissatisfactory therapeutic effects. Additionally, the quick clearance, systemic side effects, and low concentration at the tumor site of conventional pyroptosis reagents restrict their use in clinical cancer therapy. Here, we described a combination therapy that induces tumor cell pyroptosis via the use of ultrasound-targeted microbubble destruction (UTMD) in combination with DNA demethylation. The combined application of UTMD and hydralazine-loaded nanodroplets (HYD-NDs) can lead to the rapid release of HYD (a demethylation drug), which can cause the up-regulation of GSDME expression, and produce reactive oxygen species (ROS) by UTMD to cleave up-regulated GSDME, thereby inducing pyroptosis. HYD-NDs combined with ultrasound (US) group had the strongest tumor inhibition effect, and the tumor inhibition rate was 87.15% (HYD-NDs group: 51.41 ± 3.61%, NDs + US group: 32.73%±7.72%), indicating that the strategy had a more significant synergistic anti-tumor effect. In addition, as a new drug delivery carrier, HYD-NDs have great biosafety, tumor targeting, and ultrasound imaging performance. According to the results, the combined therapy reasonably regulated the process of tumor cell pyroptosis, which offered a new strategy for optimizing the therapy of GSDME-silenced solid tumors.

Transcranial Doppler Ultrasonography detection on cerebral infarction and blood vessels to evaluate hypoxic ischemic encephalopathy modeling

BACKGROUND

This study aimed to observe changes of rats' brain infarction and blood vessels during neonatal hypoxic ischemic encephalopathy (NHIE) modeling by Transcranial Doppler Ultrasonography (TCD) so as to assess the feasibility of TCD in evaluating NHIE modeling.

METHODS

Postnatal 7-days (d)-old Sprague Dawley (SD) rats were divided into the Sham group, hypoxic-ischemic (HI) group, and hypoxia (H) group. Rats in the HI group and H group were subjected to hypoxia-1 hour (h), 1.5 h and 2.5 h, respectively. Evaluation on brain lesion was made based on Zea-Longa scores, hematoxylin-eosin (HE) staining and Nissl staining. The brain infarction and blood vessels of rats were monitored and analyzed under TCD. Correlation analysis was applied to reveal the connection between hypoxic duration and infarct size detected by TCD or Nissl staining.

RESULTS

In H and HI modeling, longer duration of hypoxia was associated with higher Zea-Longa scores and more severe nerve damage. On the 1 d after modeling, necrosis was found in SD rats' brain indicated by HE and Nissl staining, which was aggravated as hypoxic duration prolonged. Alteration of brain structures and blood vessels of SD rats was displayed in Sham, HI and H rats under TCD. TCD images for coronal section revealed that brain infarct was detected at the cortex and there was marked cerebrovascular back-flow of HI rats regardless of hypoxic duration. On the 7 d after modeling, similar infarct was detected under TCD at the cortex of HI rats in hypoxia-1 h, 1.5 h and 2.5 h groups, whereas the morphological changes were deteriorated with longer hypoxic time. Correlation analysis revealed positive correlation of hypoxic duration with infarct size detected by histological detection and TCD.

CONCLUSIONS

TCD dynamically monitored cerebral infarction after NHIE modeling, which will be potentially served as a useful auxiliary method for future animal experimental modeling evaluation in the case of less animal sacrifice.

The Evolution and Recent Trends in Acoustic Targeting of Encapsulated Drugs to Solid Tumors: Strategies beyond Sonoporation

Despite recent advancements in ultrasound-mediated drug delivery and the remarkable success observed in pre-clinical studies, no delivery platform utilizing ultrasound contrast agents has yet received FDA approval. The sonoporation effect was a game-changing discovery with a promising future in clinical settings. Various clinical trials are underway to assess sonoporation's efficacy in treating solid tumors; however, there are disagreements on its applicability to the broader population due to long-term safety issues. In this review, we first discuss how acoustic targeting of drugs gained importance in cancer pharmaceutics. Then, we discuss ultrasound-targeting strategies that have been less explored yet hold a promising future. We aim to shed light on recent innovations in ultrasound-based drug delivery including newer designs of ultrasound-sensitive particles specifically tailored for pharmaceutical usage.

Ultrasound-guided puncture into newborn rat brain

Since the brain structure of neonatal rats was not fully formed during the first 4 days, it cannot be detected using ultrasound. The objective of this study was to investigate the use of ultrasound to guide puncture in the normal coronal brain structure and determine the puncture depth of the location of the cortex, hippocampus, lateral ventricle, and striatum of newborn rats of 5-15 days. The animal was placed in a prone position. The specific positions of the cortex, hippocampus, lateral ventricle, and striatum were measured under ultrasound. Then, the rats were punctured with a stereotaxic instrument, and dye was injected. Finally, the brains of rats were taken to make frozen sections to observe the puncture results. By ultrasound, the image of the cortex, hippocampus, lateral ventricle, and striatum of the rat can be obtained and the puncture depth of the cortex (8 days: 1.02 ± 0.12, 10 days: 1.02 ± 0.08, 13 days: 1.43 ± 0.05), hippocampus (8 days: 2.63 ± 0.07, 10 days: 2.77 ± 0.14, 13 days: 2.82 ± 0.09), lateral ventricle (8 days: 2.08 ± 0.04, 10 days: 2.26 ± 0.03, 13 days: 2.40 ± 0.06), and corpus striatum (8 days: 4.57 ± 0.09, 10 days: 4.94 ± 0.31, 13 days: 5.13 ± 0.10) can be accurately measured. The rat brain structure and puncture depth changed with the age of the rats. Ultrasound technology can not only clarify the brain structure characteristics of 5-15-day-old rats but also guide the puncture and injection of the rat brain structure. The results of this study laid the foundation for the future use of ultrasound in experimental animal models of neurological diseases.

Bioactive inorganic nanomaterials for cancer theranostics

Bioactive materials are a special class of biomaterials that can react in vivo to induce a biological response or regulate biological functions, thus achieving a better curative effect than traditional inert biomaterials. For cancer theranostics, compared with organic or polymer nanomaterials, inorganic nanomaterials possess unique physical and chemical properties, have stronger mechanical stability on the basis of maintaining certain bioactivity, and are easy to be compounded with various carriers (polymer carriers, biological carriers, etc.), so as to achieve specific antitumor efficacy. After entering the nanoscale, due to the nano-size effect, high specific surface area and special nanostructures, inorganic nanomaterials exhibit unique biological effects, which significantly influence the interaction with biological organisms. Therefore, the research and applications of bioactive inorganic nanomaterials in cancer theranostics have attracted wide attention. In this review, we mainly summarize the recent progress of bioactive inorganic nanomaterials in cancer theranostics, and also introduce the definition, synthesis and modification strategies of bioactive inorganic nanomaterials. Thereafter, the applications of bioactive inorganic nanomaterials in tumor imaging and antitumor therapy, including tumor microenvironment (TME) regulation, catalytic therapy, gas therapy, regulatory cell death and immunotherapy, are discussed. Finally, the biosafety and challenges of bioactive inorganic nanomaterials are also mentioned, and their future development opportunities are prospected. This review highlights the bioapplication of bioactive inorganic nanomaterials.

Ultrafast Background-Free Ultrasound Imaging Using Blinking Nanoparticles

Localization-based ultrasound imaging methods that use microbubbles or nanodroplets offer high-resolution imaging with improved sensitivity and reduced background signal. However, these methods require long acquisition times (typically seconds to minutes), preventing their use for real-time imaging and, thus, limiting their clinical translational potential. Here, we present a new ultrafast localization method using blinking ultrasound-responsive nanoparticles (BNPs). When activated with high frame rate (1 kHz) plane wave ultrasound pulses with a mechanical index of 1.5, the BNPs incept growth of micrometer-sized bubbles, which in turn collapse and generate a blinking ultrasound signal. We showed that background-free ultrasound images could be obtained by localizing these blinking events using acquisition times as low as 11 ms. In addition, we demonstrated that BNPs enable in vivo background-free ultrasound imaging in mice. We envision that BNPs will facilitate the clinical translation of localization-based ultrasound imaging for more sensitive detection of cancer and other diseases.

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.

US/MR Bimodal Imaging-Guided Bio-Targeting Synergistic Agent for Tumor Therapy

Purpose

Breast cancer is detrimental to the health of women due to the difficulty of early diagnosis and unsatisfactory therapeutic efficacy of available breast cancer therapies. High intensity focused ultrasound (HIFU) ablation is a new method for the treatment of breast tumors, but there is a problem of low ablation efficiency. Therefore, the improvement of HIFU efficiency to combat breast cancer is immediately needed. This study aimed to describe a novel anaerobic bacteria-mediated nanoplatform, comprising synergistic HIFU therapy for breast cancer under guidance of ultrasound (US) and magnetic resonance (MR) bimodal imaging.

Methods

The PFH@CL/Fe₃O₄ nanoparticles (NPs) (Perfluorohexane (PFH) and superparamagnetic iron oxides (SPIO, Fe₃O₄) with cationic lipid (CL) NPs) were synthesized using the thin membrane hydration method. The novel nanoplatform Bifidobacterium bifidum-mediated PFH@CL/Fe₃O₄ NPs were constructed by electrostatic adsorption. Thereafter, US and MR bimodal imaging ability of B. bifidum-mediated PFH@CL/Fe₃O₄ NPs was evaluated in vitro and in vivo. Finally, the efficacy of HIFU ablation based on B. bifidum-PFH@CL/Fe₃O₄ NPs was studied.

Results

B. bifidum combined with PFH@CL/Fe₃O₄ NPs by electrostatic adsorption and enhanced the tumor targeting ability of PFH@CL/Fe₃O₄ NPs. US and MR bimodal imaging clearly displayed the distribution of the bio-targeting nanoplatform in vivo. It was conducive for accurate and effective guidance of HIFU synergistic treatment of tumors. Furthermore, PFH@CL/Fe₃O₄ NPs could form microbubbles by acoustic droplet evaporation and promote efficiency of HIFU ablation under guidance of bimodal imaging.

Conclusion

A bio-targeting nanoplatform with high stability and good physicochemical properties was constructed. The HIFU synergistic agent achieved early precision imaging of tumors and promoted therapeutic effect, monitored by US and MR bimodal imaging during the treatment process.