Assessment of Gold Nanoparticle-Mediated-Enhanced Hyperthermia Using MR-Guided High-Intensity Focused Ultrasound Ablation Procedure

Ultrasound-Based Micro-/Nanosystems for Biomedical Applications

Due to the intrinsic non-invasive nature, cost-effectiveness, high safety, and real-time capabilities, besides diagnostic imaging, ultrasound as a typical mechanical wave has been extensively developed as a physical tool for versatile biomedical applications. Especially, the prosperity of nanotechnology and nanomedicine invigorates the landscape of ultrasound-based medicine. The unprecedented surge in research enthusiasm and dedicated efforts have led to a mass of multifunctional micro-/nanosystems being applied in ultrasound biomedicine, facilitating precise diagnosis, effective treatment, and personalized theranostics. The effective deployment of versatile ultrasound-based micro-/nanosystems in biomedical applications is rooted in a profound understanding of the relationship among composition, structure, property, bioactivity, application, and performance. In this comprehensive review, we elaborate on the general principles regarding the design, synthesis, functionalization, and optimization of ultrasound-based micro-/nanosystems for abundant biomedical applications. In particular, recent advancements in ultrasound-based micro-/nanosystems for diagnostic imaging are meticulously summarized. Furthermore, we systematically elucidate state-of-the-art studies concerning recent progress in ultrasound-based micro-/nanosystems for therapeutic applications targeting various pathological abnormalities including cancer, bacterial infection, brain diseases, cardiovascular diseases, and metabolic diseases. Finally, we conclude and provide an outlook on this research field with an in-depth discussion of the challenges faced and future developments for further extensive clinical translation and application.

Promising dawn in tumor microenvironment therapy: engineering oral bacteria

Despite decades of research, cancer continues to be a major global health concern. The human mouth appears to be a multiplicity of local environments communicating with other organs and causing diseases via microbes. Nowadays, the role of oral microbes in the development and progression of cancer has received increasing scrutiny. At the same time, bioengineering technology and nanotechnology is growing rapidly, in which the physiological activities of natural bacteria are modified to improve the therapeutic efficiency of cancers. These engineered bacteria were transformed to achieve directed genetic reprogramming, selective functional reorganization and precise control. In contrast to endotoxins produced by typical genetically modified bacteria, oral flora exhibits favorable biosafety characteristics. To outline the current cognitions upon oral microbes, engineered microbes and human cancers, related literatures were searched and reviewed based on the PubMed database. We focused on a number of oral microbes and related mechanisms associated with the tumor microenvironment, which involve in cancer occurrence and development. Whether engineering oral bacteria can be a possible application of cancer therapy is worth consideration. A deeper understanding of the relationship between engineered oral bacteria and cancer therapy may enhance our knowledge of tumor pathogenesis thus providing new insights and strategies for cancer prevention and treatment.

Strategies to Reverse Hypoxic Tumor Microenvironment for Enhanced Sonodynamic Therapy

Sonodynamic therapy (SDT) has emerged as a highly effective modality for the treatment of malignant tumors owing to its powerful penetration ability, noninvasiveness, site-confined irradiation, and excellent therapeutic efficacy. However, the traditional SDT, which relies on oxygen availability, often fails to generate a satisfactory level of reactive oxygen species because of the widespread issue of hypoxia in the tumor microenvironment of solid tumors. To address this challenge, various approaches are developed to alleviate hypoxia and improve the efficiency of SDT. These strategies aim to either increase oxygen supply or prevent hypoxia exacerbation, thereby enhancing the effectiveness of SDT. In view of this, the current review provides an overview of these strategies and their underlying principles, focusing on the circulation of oxygen from consumption to external supply. The detailed research examples conducted using these strategies in combination with SDT are also discussed. Additionally, this review highlights the future prospects and challenges of the hypoxia-alleviated SDT, along with the key considerations for future clinical applications. These considerations include the development of efficient oxygen delivery systems, the accurate methods for hypoxia detection, and the exploration of combination therapies to optimize SDT outcomes.

Sono-activated materials for enhancing focused ultrasound ablation: Design and application in biomedicine

The ablation effect of focused ultrasound (FUS) has played an increasingly important role in the biomedical field over the past decades, and its non-invasive features have great advantages, especially for clinical diseases where surgical treatment is not available or appropriate. Recently, rapid advances in the adjustable morphology, enzyme-mimetic activity, and biostability of sono-activated materials have significantly promoted the medical application of FUS ablation. However, a systematic review of sono-activated materials based on FUS ablation is not yet available. This progress review focuses on the recent design, fundamental principles, and applications of sono-activated materials in the FUS ablation biomedical field. First, the different ablation mechanisms and the key factors affecting ablation are carefully determined. Then, the design of sono-activated materials with high FUS ablation efficiencies is comprehensively discussed. Subsequently, the representative biological applications are summarized in detail. Finally, the primary challenges and future perspectives are also outlined. We believe this timely review will provide key information and insights for further exploration of focused ultrasound ablation and new inspiration for designing future sono-activated materials. STATEMENT OF SIGNIFICANCE: The ablation effect of focused ultrasound (FUS) has played an increasingly important role in the biomedical field over the past decades. However, there are also some challenges of FUS ablation, such as skin burns, tumour recurrence after thermal ablation, and difficulty in controlling cavitation ablation. The rapid advance in adjustable morphology, enzyme-mimetic activity, and biostability of sono-activated materials has significantly promoted the medical application of FUS ablation. However, the systematic review of sono-activated materials based on FUS ablation is not yet available. This progress review focuses on the recent design, fundamental principles, and applications in the FUS ablation biomedical field of sono-activated materials. We believe this timely review will provide key information and insights for further exploration of FUS ablation.

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.

Recent Trend of Ultrasound-Mediated Nanoparticle Delivery for Brain Imaging and Treatment

In view of the fact that the blood-brain barrier (BBB) prevents the transport of imaging probes and therapeutic agents to the brain and thus hinders the diagnosis and treatment of brain-related disorders, methods of circumventing this problem (e.g., ultrasound-mediated nanoparticle delivery) have drawn much attention. Among the related techniques, focused ultrasound (FUS) is a favorite means of enhancing drug delivery via transient BBB opening. Photoacoustic brain imaging relies on the conversion of light into heat and the detection of ultrasound signals from contrast agents, offering the benefits of high resolution and large penetration depth. The extensive versatility and adjustable physicochemical properties of nanoparticles make them promising therapeutic agents and imaging probes, allowing for successful brain imaging and treatment through the combined action of ultrasound and nanoparticulate agents. FUS-induced BBB opening enables nanoparticle-based drug delivery systems to efficiently access the brain. Moreover, photoacoustic brain imaging using nanoparticle-based contrast agents effectively visualizes brain morphologies or diseases. Herein, we review the progress in the simultaneous use of nanoparticles and ultrasound in brain research, revealing the potential of ultrasound-mediated nanoparticle delivery for the effective diagnosis and treatment of brain disorders.

Ultrasound Responsive Smart Implantable Hydrogels for Targeted Delivery of Drugs: Reviewing Current Practices

Over the last two decades, the process of delivering therapeutic drugs to a patient with a controlled release profile has been a significant focus of drug delivery research. Scientists have given tremendous attention to ultrasound-responsive hydrogels for several decades. These smart nanosystems are more applicable than other stimuli-responsive drug delivery vehicles (ie UV-, pH- and thermal-, responsive materials) because they enable more efficient targeted treatment via relatively non-invasive means. Ultrasound (US) is capable of safely transporting energy through opaque and complex media with minimal loss of energy. It is capable of being localized to smaller regions and coupled to systems operating at various time scales. However, the properties enabling the US to propagate effectively in materials also make it very difficult to transform acoustic energy into other forms that may be used. Recent research from a variety of domains has attempted to deal with this issue, proving that ultrasonic effects can be used to control chemical and physical systems with remarkable specificity. By obviating the need for multiple intravenous injections, implantable US responsive hydrogel systems can enhance the quality of life for patients who undergo treatment with a varied dosage regimen. Ideally, the ease of self-dosing in these systems would lead to increased patient compliance with a particular therapy as well. However, excessive literature has been reported based on implanted US responsive hydrogel in various fields, but there is no comprehensive review article showing the strategies to control drug delivery profile. So, this review was aimed at discussing the current strategies for controlling and targeting drug delivery profiles using implantable hydrogel systems.

Spatiotemporal control of engineered bacteria to express interferon-γ by focused ultrasound for tumor immunotherapy

Bacteria-based tumor therapy has recently attracted wide attentions due to its unique capability in targeting tumors and preferentially colonizing the core area of the tumor. Various therapeutic genes are also harbored into these engineering bacteria to enhance their anti-tumor efficacy. However, it is difficult to spatiotemporally control the expression of these inserted genes in the tumor site. Here, we engineer an ultrasound-responsive bacterium (URB) which can induce the expression of exogenous genes in an ultrasound-controllable manner. Owing to the advantage of ultrasound in tissue penetration, an acoustic remote control of bacterial gene expression can be realized by designing a temperature-actuated genetic switch. Cytokine interferon-γ (IFN-γ), an important immune regulatory molecule that plays a significant role in tumor immunotherapy, is used to test the system. Our results show that brief hyperthermia induced by focused ultrasound promotes the expression of IFN-γ gene, improving anti-tumor efficacy of URB in vitro and in vivo. Our study provides an alternative strategy for bacteria-mediated tumor immunotherapy.

Nanotechnology-Based Diagnostic and Therapeutic Strategies for Neuroblastoma

Neuroblastoma (NB), as the most common extracranial solid tumor in childhood, is one of the critical culprits affecting children's health. Given the heterogeneity and invisibility of NB tumors, the existing diagnostic and therapeutic approaches are inadequate and ineffective in early screening and prognostic improvement. With the rapid innovation and development of nanotechnology, nanomedicines have attracted widespread attention in the field of oncology research for their excellent physiological and chemical properties. In this review, we first explored the current common obstacles in the diagnosis and treatment of NB. Then we comprehensively summarized the advancements in nanotechnology-based multimodal synergistic diagnosis and treatment of NB and elucidate the underlying mechanisms. In addition, a discussion of the pending challenges in biocompatibility and toxicity of nanomedicine was conducted. Finally, we described the development and application status of nanomaterials against some of the recognized targets in the field of NB research, and pointed out prospects for nanomedicine-based precision diagnosis and therapy of NB.

Recent Advancements in Ultrasound Transducer: From Material Strategies to Biomedical Applications

Ultrasound is extensively studied for biomedical engineering applications. As the core part of the ultrasonic system, the ultrasound transducer plays a significant role. For the purpose of meeting the requirement of precision medicine, the main challenge for the development of ultrasound transducer is to further enhance its performance. In this article, an overview of recent developments in ultrasound transducer technologies that use a variety of material strategies and device designs based on both the piezoelectric and photoacoustic mechanisms is provided. Practical applications are also presented, including ultrasound imaging, ultrasound therapy, particle/cell manipulation, drug delivery, and nerve stimulation. Finally, perspectives and opportunities are also highlighted.

Ultrasound and nanomaterial: an efficient pair to fight cancer

Ultrasounds are often used in cancer treatment protocols, e.g. to collect tumor tissues in the right location using ultrasound-guided biopsy, to image the region of the tumor using more affordable and easier to use apparatus than MRI and CT, or to ablate tumor tissues using HIFU. The efficacy of these methods can be further improved by combining them with various nano-systems, thus enabling: (i) a better resolution of ultrasound imaging, allowing for example the visualization of angiogenic blood vessels, (ii) the specific tumor targeting of anti-tumor chemotherapeutic drugs or gases attached to or encapsulated in nano-systems and released in a controlled manner in the tumor under ultrasound application, (iii) tumor treatment at tumor site using more moderate heating temperatures than with HIFU. Furthermore, some nano-systems display adjustable sizes, i.e. nanobubbles can grow into micro-bubbles. Such dual size is advantageous since it enables gathering within the same unit the targeting properties of nano bubbles via EPR effect and the enhanced ultrasound contrasting properties of micro bubbles. Interestingly, the way in which nano-systems act against a tumor could in principle also be adjusted by accurately selecting the nano-system among a large choice and by tuning the values of the ultrasound parameters, which can lead, due to their mechanical nature, to specific effects such as cavitation that are usually not observed with purely electromagnetic waves and can potentially help destroying the tumor. This review highlights the clinical potential of these combined treatments that can improve the benefit/risk ratio of current cancer treatments.

Biological Utility of Fluorinated Compounds: from Materials Design to Molecular Imaging, Therapeutics and Environmental Remediation

The applications of fluorinated molecules in bioengineering and nanotechnology are expanding rapidly with the controlled introduction of fluorine being broadly studied due to the unique properties of C-F bonds. This review will focus on the design and utility of C-F containing materials in imaging, therapeutics, and environmental applications with a central theme being the importance of controlling fluorine-fluorine interactions and understanding how such interactions impact biological behavior. Low natural abundance of fluorine is shown to provide sensitivity and background advantages for imaging and detection of a variety of diseases with ¹⁹F magnetic resonance imaging, ¹⁸F positron emission tomography and ultrasound discussed as illustrative examples. The presence of C-F bonds can also be used to tailor membrane permeability and pharmacokinetic properties of drugs and delivery agents for enhanced cell uptake and therapeutics. A key message of this review is that while the promise of C-F containing materials is significant, a subset of highly fluorinated compounds such as per- and polyfluoroalkyl substances (PFAS), have been identified as posing a potential risk to human health. The unique properties of the C-F bond and the significant potential for fluorine-fluorine interactions in PFAS structures necessitate the development of new strategies for facile and efficient environmental removal and remediation. Recent progress in the development of fluorine-containing compounds as molecular imaging and therapeutic agents will be reviewed and their design features contrasted with environmental and health risks for PFAS systems. Finally, present challenges and future directions in the exploitation of the biological aspects of fluorinated systems will be described.

Bubble-Assisted HIFU Ablation Enabled by Calcium Peroxide

High intensity focused ultrasound (HIFU), as one of the most advanced and preferred cancer treatment modes, has shown great promise due to its minimal invasiveness and irradiation-free feature. However, a...

Ultrasound Neuromodulation: Integrating Medicine and Engineering for Neurological Disease Treatment

Abstract Neurological diseases associated with dysfunctions of neural circuits, including Alzheimer’s disease (AD), depression and epilepsy, have been increasingly prevalent. To tackle these issues, artificial stimulation or regulation of specific neural circuits and nuclei are employed to alleviate or cure certain neurological diseases. In particular, ultrasound neuromodulation has been an emerging interdisciplinary approach, which integrates medicine and engineering methodologies in the treatment. With the development of medicine and engineering, ultrasound neuromodulation has gradually been applied in the treatment of central nervous system diseases. In this review, we aimed to summarize the mechanism of ultrasound neuromodulation and the advances of focused ultrasound (FUS) in neuromodulation in recent years, with a special emphasis on its application in central nervous system disease treatment. FUS showed great feasibility in the treatment of epilepsy, tremor, AD, depression, and brain trauma. We also suggested future directions of ultrasound neuromodulation in clinical settings, with a focus on its fusion with genetic engineering or nanotechnology.

Gas-stabilizing nanoparticles for ultrasound imaging and therapy of cancer

The use of ultrasound in the clinic has been long established for cancer detection and image-guided tissue biopsies. In addition, ultrasound-based methods have been widely explored to develop more effective cancer therapies such as localized drug delivery, sonodynamic therapy, and focused ultrasound surgery. Stabilized fluorocarbon microbubbles have been in use as contrast agents for ultrasound imaging in the clinic for several decades. It is also known that microbubble cavitation could generate thermal, mechanical, and chemical effects in the tissue to improve ultrasound-based therapies. However, the large size, poor stability, and short-term cavitation activity of microbubbles limit their applications in cancer imaging and therapy. This review will focus on an alternative type of ultrasound responsive material; gas-stabilizing nanoparticles, which can address the limitations of microbubbles with their nanoscale size, robustness, and high cavitation activity. This review will be of interest to researchers who wish to explore new agents to develop improved methods for molecular ultrasound imaging and therapy of cancer.

Image-guided locoregional non-intravascular interventional treatments for hepatocellular carcinoma: Current status

Hepatocellular carcinoma (HCC) is one of the most deadly and frequent cancers worldwide, although great advancement in the treatment of this malignancy have been made within the past few decades. It continues to be a major health issue due to an increasing incidence and a poor prognosis. The majority of patients have their HCC diagnosed at an intermediate or advanced stage in theUSA or China. Curative therapy such as surgical resection or liver transplantation is not considered anoption of treatment at these stages.

Transarterial chemoembolization (TACE), the most widely used locoregional therapeutic approach, used to be the mainstay of treatment for cases with unresectable cancer entities. However, for those patients with hypovascular tumors or impaired liver function reserve, TACE is a suboptimal treatment option. For example, embolization does not result in complete coverage of a hypovascular tumor, and may rather promotes postoperative tumor recurrence, or leave residual tumor, in these TACE-resistance patients. In addition, TACE carries a higher risk of hepatic decompensation in patients with poor liver function or reserve.

Non-vascular interventional locoregional therapies for HCC include radiofrequency ablation (RFA), microwave ablation (MWA), high-intensity focused ultrasound (HIFU), laser-induced thermotherapy (LITT), cryosurgical ablation (CSA), irreversible Electroporation (IRE), percutaneous ethanol injection (PEI), and brachytherapy. Recent advancements in these techniques have significantly improved the treatment efficacy of HCC and expanded the population of patients who qualify for treatment. This review embraces the current status of imaging-guided locoregional non-intravascular interventional treatments for HCCs, with a primary focus on the clinical evaluation and assessment of the efficacy of combined therapies using these interventional techniques.

Magnetic mediators for ultrasound theranostics

The theranostics paradigm is based on the concept of combining therapeutic and diagnostic modalities into one platform to improve the effectiveness of treatment. Combinations of multiple modalities provide numerous medical advantages and are enabled by nano- and micron-sized mediators. Here we review recent advancements in the field of ultrasound theranostics and the use of magnetic materials as mediators. Several subdisciplines are described in detail, including controlled drug delivery and release, ultrasound hyperthermia, magneto-ultrasonic heating, sonodynamic therapy, magnetoacoustic imaging, ultrasonic wave generation by magnetic fields, and ultrasound tomography. The continuous progress and improvement in theranostic materials, methods, and physical computing models have created undeniable possibilities for the development of new approaches. We discuss the prospects of ultrasound theranostics and possible expansions of other studies to the theranostic context.

Comprehensive review on ultrasound-responsive theranostic nanomaterials: mechanisms, structures and medical applications

The field of theranostics has been rapidly growing in recent years and nanotechnology has played a major role in this growth. Nanomaterials can be constructed to respond to a variety of different stimuli which can be internal (enzyme activity, redox potential, pH changes, temperature changes) or external (light, heat, magnetic fields, ultrasound). Theranostic nanomaterials can respond by producing an imaging signal and/or a therapeutic effect, which frequently involves cell death. Since ultrasound (US) is already well established as a clinical imaging modality, it is attractive to combine it with rationally designed nanoparticles for theranostics. The mechanisms of US interactions include cavitation microbubbles (MBs), acoustic droplet vaporization, acoustic radiation force, localized thermal effects, reactive oxygen species generation, sonoluminescence, and sonoporation. These effects can result in the release of encapsulated drugs or genes at the site of interest as well as cell death and considerable image enhancement. The present review discusses US-responsive theranostic nanomaterials under the following categories: MBs, micelles, liposomes (conventional and echogenic), niosomes, nanoemulsions, polymeric nanoparticles, chitosan nanocapsules, dendrimers, hydrogels, nanogels, gold nanoparticles, titania nanostructures, carbon nanostructures, mesoporous silica nanoparticles, fuel-free nano/micromotors.

Carbon nanotube-mediated high intensity focused ultrasound

High intensity focused ultrasound (HIFU) is emerging as a novel therapeutic technique for cancer treatment through a hyperthermal mechanism using ultrasound. However, collateral thermal damages to healthy tissue and skin burns due to the use of high levels of ultrasonic energy during HIFU treatment remain major challenges to clinical application. The main objective of the current study is to evaluate the potential of carbon nanotubes (CNTs) as effective absorption-enhancing agents for HIFU to mediate the heating process at low ultrasonic power levels, and consequently upgrade hyperthermal therapeutic effects of HIFU. An experimental study using in vitro tissue phantoms was conducted to assess the effects of CNTs on HIFU’s heating mechanism. Detailed information was extracted from the experiments for thermal analysis, including rate of absorbed energy density and temperature rise profile at the focal region. Parametric studies were carried out, revealing the effects of ultrasound parameters (ultrasonic power and driving frequency) on the performance of CNTs in various concentrations. The results indicated that CNTs significantly enhanced the thermal effect of HIFU by elevating energy absorption rate and consequential temperature rise. Moreover, it was demonstrated that an increase in ultrasonic power and driving frequency could lead to a better performance of CNTs during HIFU ablation procedures; the effects of CNTs could be further enhanced by increasing their volume concentration inside the medium.

Low intensity focused ultrasound responsive microcapsules for non-ablative ultrafast intracellular release of small molecules

Focused ultrasound (FU) is in demand for clinical cancer therapy, but the possible thermal injury to the normal peripheral tissues limits the usage of the ablative FU for tumors with a large size; therefore research efforts have been made to minimize the possible side effects induced by the FU treatment. Non-ablative focused ultrasound assisted chemotherapy could open a new avenue for the development of cancer therapy technology. Here, low intensity focused ultrasound (LIFU) for controlled quick intracellular release of small molecules (Mw ≤ 1000 Da) without acute cell damage is demonstrated. The release is achieved by a composite poly(allylamine hydrochloride) (PAH)/poly-(sodium 4-styrenesulfonate) (PSS)/SiO2 microcapsules which are highly sensitive to LIFU and can be effectively broken by weak cavitation effects. Most PAH/PSS/SiO2 capsules in B50 rat neuronal cells can be ruptured and release rhodamine B (Rh-B) into the cytosol within only 30 s of 0.75 W cm-2 LIFU treatment, as demonstrated by the CLSM results. While the same LIFU treatment shows no obvious damage to cells, as proved by the live/dead experiment, showing that 90% of cells remain alive.

A Promising Platform of Magnetic Nanofluid and Ultrasonic Treatment for Cancer Hyperthermia Therapy: In Vitro and in Vivo Study

Localized hyperthermia is a very promising cancer therapy approach especially when stimulated by the exceptional properties of iron oxide magnetic nanoparticles (MNPs). This approach is a highly site-specific method for localized heating of bodily tissue without any harmful side effects that could revolutionize the practice of cancer therapy. The main objective of this study was to evaluate the cancer cell-destroying capability of MNPs in combination with ultrasound treatment as an innovative sonomagnetic cancer therapy. Magnetic nanofluids (MNFs) were synthesized by co-precipitation/sonochemical techniques in an aqueous medium without any surfactant and/or capping agent. The physicochemical characteristics of the prepared MNFs were investigated with scanning electron microscopy, transmission electron microscopy, X-ray diffractometry, Fourier transform infrared and vibrating sample magnetometry. The MNFs was used as a mediator and sonosensitizer to destroy tumor tissue when irradiated by ultrasound waves. The antitumor efficiency of MNFs in combination with pulsed ultrasound (1.5 W/cm², 1 MHz) was evaluated in vitro and in vivo. In vitro efficacy was estimated by determining the cell viability of Ehrlich ascites carcinoma cells. For in vivo experiments, female mice were inoculated subcutaneously with Ehrlich carcinoma cells to establish solid Ehrlich carcinoma. The cytotoxic concentration of MNFs (400 µg/mL) was injected intratumorally and exposed to pulsed ultrasound (1.5 W/cm², 1 MHz). The cytotoxic effect was determined in terms of tumor growth rate, apoptosis and necrosis. Our results revealed that MNFs in the presence of pulsed ultrasound cause a significant increase in the cytotoxicity effect on tumor cells. This study illustrates the high efficiency of cancer therapy as assisted by both ultrasound and magnetic nanofluid.

Laser-induced optothermal response of gold nanoparticles: From a physical viewpoint to cancer treatment application

Gold nanoparticles (GNPs)-based photothermal therapy (PTT) is a promising minimally invasive thermal therapy for the treatment of focal malignancies. Although GNPs-based PTT has been known for over two decades and GNPs possess unique properties as therapeutic agents, the delivery of a safe and effective therapy is still an open question. This review aims at providing relevant and recent information on the usage of GNPs in combination with the laser to treat cancers, pointing out the practical aspects that bear on the therapy outcome. Emphasis is given to the assessment of the GNPs' properties and the physical mechanisms underlying the laser-induced heat generation in GNPs-loaded tissues. The main techniques available for temperature measurement and the current theoretical simulation approaches predicting the therapeutic outcome are reviewed. Topical challenges in delivering safe thermal dosage are also presented with the aim to discuss the state-of-the-art and the future perspective in the field of GNPs-mediated PTT.

Protein-based nanoplatform for detection of tumorigenic polyps in the colon via noninvasive mucosal routes

The use of nanoparticulate systems to diagnose and treat tumors has gained momentum with the rapid development of nanomedicine. Many nanotheranostics fail due to insufficient bioavailability and low accumulation at the tumor site, resulting in undesirable side effects. We describe the use of an engineered hepatitis E viral nanoparticle (HEVNP) with enhanced bioavailability, tissue retention and mucosal penetration capacities. HEVNP is a modular nanocapsule that can encapsulate heterologous nucleotides, proteins and inorganic metals, such as ferrite oxide nanoparticles. Additionally, the exterior protruding arms of HEVNP is composed of loops that are used for chemical coupling of targeting and therapeutic peptides. We propose the use of HEVNP to target colorectal cancer (i.e., polyps) with imaging-guided delivery using colonoscopy.

Multifunctional Nanoparticles Encapsulating Astragalus Polysaccharide and Gold Nanorods in Combination with Focused Ultrasound for the Treatment of Breast Cancer

Purpose

Focused ultrasound (FUS) is a noninvasive method to produce thermal and mechanical destruction along with an immune-stimulatory effect against cancer. However, FUS ablation alone appears insufficient to generate consistent antitumor immunity. In this study, a multifunctional nanoparticle was designed to boost FUS-induced immune effects and achieve systemic, long-lasting antitumor immunity, along with imaging and thermal enhancement.

Materials and Methods

PEGylated PLGA nanoparticles encapsulating astragalus polysaccharides (APS) and gold nanorods (AuNRs) were constructed by a simple double emulsion method, characterized, and tested for cytotoxicity. The abilities of PA imaging and thermal-synergetic ablation efficiency were analyzed in vitro and in vivo. The immune-synergistic effect on dendritic cell (DC) differentiation in vitro and the immune response in vivo were also evaluated.

Results

The obtained APS/AuNR/PLGA-PEG nanoparticles have an average diameter of 255.00±0.1717 nm and an APS-loading efficiency of 54.89±2.07%, demonstrating their PA imaging capability and high biocompatibility both in vitro and in vivo. In addition, the as-prepared nanoparticles achieved a higher necrosis cell rate and induced apoptosis rate in an in vitro cell suspension assay, greater necrosis area and decreased energy efficiency factor (EEF) in an in vivo rabbit liver assay, and remarkable thermal-synergic performance. In particular, the nanoparticles upregulated the expression of MHC-II, CD80 and CD86 on cocultured DCs in vitro, followed by declining phagocytic function and enhanced interleukin (IL)-12 and interferon (INF)-γ production. Furthermore, they boosted the production of tumor necrosis factor (TNF)-α, IFN-γ, IL-4, IL-10, and IgG1 (P< 0.001) but not IgG2a. Immune promotion peaked on day 3 after FUS in vivo.

Conclusion

The multifunctional APS/AuNR/PLGA-PEG nanoparticles can serve as an excellent synergistic agent for FUS therapy, facilitating real-time imaging, promoting thermal ablation effects, and boosting FUS-induced immune effects, which have the potential to be used for further clinical FUS treatment.

Production of gold/silver doped carbon nanocomposites for effective photothermal therapy of colon cancer

Surgery followed by adjuvant chemotherapy is a reliable therapy for colon cancer, but is associated with side effects and risks. Recent advancements in nanobioengineering in the form of targeted nanoparticles, cubosomes, liposomes, nanosheets, nanorods, quantum dots have generated substantial advancements in theranostics of colon cancer decreasing the cytotoxic drugs' side effects. We describe a facile mechanism of preparation of hybrid nanocomposite encompassing Au and Ag. Preparation of hybrid nanocomposite is one step process which may be easily escalated. The nanocomposite was characterized using transmission eleactron microscopy, energy dispersive X-Ray spectroscopy, X-ray photoelectron spectroscopy, Fourier transform infra-red spectroscopy, UV-Vis spectroscopy, photoluminescence and cytotoxic studies. In-vivo studies were carried out in Balb/c mice. Photothermal heating experiments in HeLa cells were promising and the characterization studies clearly indicated the formation of hybrid nanocomposite. In-vivo experiments confirmed the efficacy of treatment, along with involvement of epigenetic regulation, which may be helpful in translation from research to clinical applications.

Magnetic nanoparticles-enhanced focused ultrasound heating: size effect, mechanism, and performance analysis

High intensity focused ultrasound (HIFU) has attracted great interest as a new energy-based technique to treat disordered tissues, such as tumors, through a hyperthermal mechanism using ultrasonic waves. However, long treatment times and collateral damage to healthy tissues due to high acoustic powers are still challenges for the clinical application of HIFU. One possible strategy to enhance the deposition efficiency of HIFU at the tumor site is to employ magnetic nanoparticles (MNPs) as ultrasound absorption agents for the thermal therapy. The objectives of the current study are threefold: (i) to examine the effects of MNP features, including the size and volume concentration, on the thermal mechanism of HIFU (ii) to investigate the performance of MNPs as they were exposed to ultrasound fields at different ranges of power and frequency (iii) and to study the interaction mechanism between MNPs and ultrasonic waves during the MNPs-enhanced HIFU process. To this end, we developed an ultrasound-guided HIFU system to conduct an in vitro experimental study on tissue phantoms containing MNPs of different sizes and volume concentrations. A set of HIFU parameters such as temperature rise and the rate of absorbed energy was monitored to examine the role of MNPs during the NPs-enhanced HIFU thermal procedure. Results showed that the MNPs significantly improved the thermal effect of HIFU by enhancing the rate of energy converted to heat and the temperature rise at the focal region. Moreover, it was demonstrated that the increase of MNP size and volume concentration greatly enhanced the HIFU parameters; the effects of MNPs were further improved by increasing the power and frequency of acoustic field.

Analytical and Numerical Model of High Intensity Focused Ultrasound Enhanced With Nanoparticles

OBJECTIVE

High intensity focused ultrasound (HIFU) is a new noninvasive therapeutics that allows local treatment of solid tumors through a hyperthermal mechanism using ultrasonic energy. One promising strategy to increase the thermal efficiency of HIFU is to employ nanoparticles (NPs) as ultrasound agents for the hyperthermia procedure. However, the interaction mechanism between NPs and ultrasonic waves has not been well understood.

METHODS

In an effort to investigate the heating process of NPs-enhanced HIFU, we derived a set of HIFU equations governing the temperature variation during the thermal ablation based on the principle of conservation of energy for heat transfer mechanism. A numerical model was developed to solve the HIFU equations to simulate the absorption mechanism of HIFU in the presence of NPs, the consequent heat transfer process, and the temperature rise profile during the sonication period. The accuracy of numerical model was verified by performing a series of experiments on tissue-mimicking phantoms embedded with magnetic NPs (MNPs).

RESULTS

The transport processes taking place at the boundaries between NPs and surrounding medium played the major role in the temperature rise during HIFU sonication. Besides, the effects of MNPs on rising temperature were improved by amplifying the ultrasonic power and frequency as well as by increasing the MNP concentration.

CONCLUSION

A quantitative comparison with experimental results demonstrated the potential of the numerical model to accurately predict the heating mechanism of HIFU mediated by NPs.

SIGNIFICANCE

The proposed method can help with simulation of HIFU when NPs are employed as ultrasound agents.

Advanced Nanotechnology Leading the Way to Multimodal Imaging-Guided Precision Surgical Therapy

Surgical resection is the primary and most effective treatment for most patients with solid tumors. However, patients suffer from postoperative recurrence and metastasis. In the past years, emerging nanotechnology has led the way to minimally invasive, precision and intelligent oncological surgery after the rapid development of minimally invasive surgical technology. Advanced nanotechnology in the construction of nanomaterials (NMs) for precision imaging-guided surgery (IGS) as well as surgery-assisted synergistic therapy is summarized, thereby unlocking the advantages of nanotechnology in multimodal IGS-assisted precision synergistic cancer therapy. First, mechanisms and principles of NMs to surgical targets are briefly introduced. Multimodal imaging based on molecular imaging technologies provides a practical method to achieve intraoperative visualization with high resolution and deep tissue penetration. Moreover, multifunctional NMs synergize surgery with adjuvant therapy (e.g., chemotherapy, immunotherapy, phototherapy) to eliminate residual lesions. Finally, key issues in the development of ideal theranostic NMs associated with surgical applications and challenges of clinical transformation are discussed to push forward further development of NMs for multimodal IGS-assisted precision synergistic cancer therapy.

Single enzyme loaded nanoparticles for combinational ultrasound-guided focused ultrasound ablation and hypoxia-relieved chemotherapy

Constructing nanosystems that synergistically combine therapeutic and diagnostic features is of great interest to the nanomedicine community but also remains a tremendous challenge. Methods: In this work, we report novel catalytic nanoparticles composed of the enzyme catalase, encapsulated in a polymer shell and surface decorated with pH-sensitive poly(ethylene glycol) (PEGylated nCAT). These nanoparticles were used as a promoter for ultrasound (US)-guided focused ultrasound (FUS) ablation and hypoxia alleviation for application in Doxorubicin-based chemotherapy. Results: The PEGylated nCAT produced highly effectively O2 from endogenous H2O2 to ameliorate the hypoxic and therefore poor-acoustic tumor environment. The generated O2 was utilized as 1) a contrast agent for US imaging; 2) strengthening agent for FUS ablation and 3) normoxia inducer to enhance chemotherapeutic efficacy. The PEGylated nCAT exhibited favorable enzyme activity after long-term storage, and after exposure to proteolytic conditions and elevated temperatures. The pH-responsive PEGylation contributed on the one hand to an extended in vivo circulation time over 48 h and on the other hand enabled PEG cleavage in the vicinity of cancer cells to facilitate cellular uptake. Conclusion: The developed PEGylated nCAT can therefore effectively combine US-guided FUS and chemotherapy and can be regarded as a highly promising theranostic platform.

Comparison of Heat Transfer Enhancement Between Magnetic and Gold Nanoparticles During HIFU Sonication

Long procedure times and collateral damage remain challenges in high-intensity focused ultrasound (HIFU) medical procedures. Magnetic nanoparticles (mNPs) and gold nanoparticles (gNPs) have the potential to reduce the acoustic intensity and/or exposure time required in these procedures. In this research, we investigated relative advantages of using gNPs and mNPs during HIFU thermal-ablation procedures. Tissue-mimicking phantoms containing embedded thermocouples (TCs) and physiologically acceptable concentrations (0.0625% and 0.125%) of gNPs were sonicated at acoustic powers of 5.2 W, 9.2 W, and 14.5 W, for 30 s. It was observed that when the concentration of gNPs was doubled from 0.0625% to 0.125%, the temperature rise increased by 80% for a power of 5.2 W. For a fixed concentration (0.0625%), the energy absorption was 1.7 times greater for mNPs than gNPs for a power of 5.2 W. Also, for the power of 14.5 W, the sonication time required to generate a lesion volume of 50 mm3 decreased by 1.4 times using mNPs, compared with gNPs, at a concentration of 0.0625%. We conclude that mNPs are more likely than gNPs to produce a thermal enhancement in HIFU ablation procedures.

Enhancing Thermal Effect of Focused Ultrasound Therapy Using Gold Nanoparticles

High intensity focused ultrasound (HIFU) has gained increasing attention as a noninvasive therapeutic method for wide range of biomedical applications from drug delivery to cancer treatment. However, high level of ultrasonic power required for efficient HIFU treatment can cause adverse effects such as damage to surrounding healthy tissues and skin burns. One of the strategies to improve the therapeutic mechanism of HIFU is to use ultrasound absorption agents during the treatment. The objectives of current study are to investigate the feasibility of adopting gold nanoparticles (AuNPs) as ultrasound absorption agents to enhance the HIFU thermal ablation when the NPs were injected locally to the focal region; and to examine the dose effects of AuNPs on both heating and cooling mechanisms of HIFU. To this end, we conducted an experimental study on tissue-mimicking phantoms where AuNPs were injected to the focal region under the guidance of ultrasound imaging. A set of thermal parameters including temperature, specific absorption rate of acoustic energy, and cooling rate were measured to monitor the mechanism of AuNPs-mediated HIFU. The results suggest that both heating and cooling rates of HIFU procedure could be greatly improved by injecting AuNPs, which demonstrates the feasibility of using AuNPs to reduce the level of ultrasonic power from extracorporeal source for HIFU treatment.

Assessment of Enhanced Thermal Effect Due to Gold Nanoparticles during MR-Guided High-Intensity Focused Ultrasound (HIFU) Procedures Using a Mouse-Tumor Model

An in vivo study was conducted using a mouse tumor model, to assess the utility of using gold nanoparticles (gNPs) during HIFU procedures to locally enhance heating at low powers. Tumors were grown using melanoma tumor cells (B16/F10) subcutaneously on the right flanks of mice (C57Bl/6J). Physiologically relevant concentrations (0 and 0.125%) of gNPs were directly injected into the tumors. Sonications at acoustic powers of 10 and 30 W were performed for a duration of 16 s inside a magnetic-resonance system. Temperature increases and lesion volumes were calculated and compared for procedures with and without gNPs. Histopathology study was conducted using a cleaved caspase 3 antibody and hematoxylin and eosin staining after removing the tumors from the mice. For an acoustic power of 30 W, end-of-sonication temperature increases of 25.4 ± 3.8 °C (0% gNP) and 42.2 ± 4.6 °C (0.125% gNP) were measured. Using cleaved caspase 3 antibody, it was observed that more than 1% of nuclei are affected in the case of 0.125% and 30 W but only 0.01% of nuclei are affected in the 0% case. For 30 W and a gNP concentration of 0.125%, a lesion volume of 0.33 ± 0.22 mm³ was obtained, while no lesion was observed without gNP's.

On-Demand Detaching Nanosystem for the Spatiotemporal Control of Cancer Theranostics

Engineering multiple theranostic modalities into a single nanoscale entity holds great potential to rejuvenate cancer treatments; however, enabling the sophisticated spatiotemporal control of each component for maximizing theranostic improvement and minimizing side effects concurrently remains a challenge. Herein, an intelligent detachable "nanorocket" is developed to sequentially manipulate and optimize multitheranostic processes for magnetic resonance-assisted ultrasound-drug combined therapy (MR-HIFU-Drug). The "nanorocket" is constructed by integrating multicomponent (MnCO₃, doxorubicin, silica) on the pH-sensitive CaCO₃ nanoparticles step by step via cation exchange and controlled heterogeneous nucleation, in which doxorubicin is encapsulated in both carbonates and silica component. The "nanorocket" can initiate sequential detachment in the acidic tumor microenvironment. Specifically, carbonates decompose instantly, releasing Mn²⁺ as the MR contrast agent and leaving hollow silica nanostructure behind as the HIFU synergistic agent. Consequently, burst release of drug is also triggered, further triggering the degradation of silica, which in turn regulates the slow release of drug from the silica matrix. Thus, efficient tumor inhibition is achieved by enhanced HIFU ablation and biphase release of doxorubicin with a stepwise clearance of Mn and Si. This work establishes a system for the systematic spatiotemporal dispatch of diverse theranostic components for the balance of efficacy and safety in cancer theranostics.

Colloids, nanoparticles, and materials for imaging, delivery, ablation, and theranostics by focused ultrasound (FUS)

This review focuses on different materials and contrast agents that sensitize imaging and therapy with Focused Ultrasound (FUS). At high intensities, FUS is capable of selectively ablating tissue with focus on the millimeter scale, presenting an alternative to surgical intervention or management of malignant growth. At low intensities, FUS can be also used for other medical applications such as local delivery of drugs and blood brain barrier opening (BBBO). Contrast agents offer an opportunity to increase selective acoustic absorption or facilitate destructive cavitation processes by converting incident acoustic energy into thermal and mechanical energy. First, we review the history of FUS and its effects on living tissue. Next, we present different colloidal or nanoparticulate approaches to sensitizing FUS, for example using microbubbles, phase-shift emulsions, hollow-shelled nanoparticles, or hydrophobic silica surfaces. Exploring the science behind these interactions, we also discuss ways to make stimulus-responsive, or "turn-on" contrast agents for improved selectivity. Finally, we discuss acoustically-active hydrogels and membranes. This review will be of interest to those working in materials who wish to explore new applications in acoustics and those in acoustics who are seeking new agents to improve the efficacy of their approaches.

Energy-Converting Nanomedicine

Serious side effects to surrounding normal tissues and unsatisfactory therapeutic efficacy hamper the further clinic applications of conventional cancer-therapeutic strategies, such as chemotherapy and surgery. The fast development of nanotechnology provides unprecedented superiorities for cancer therapeutics. Externally activatable therapeutic modalities mediated by nanomaterials, relying on highly effective energy transformation to release therapeutic elements/effects (cytotoxic reactive oxygen species, thermal effect, photoelectric effect, Compton effect, cavitation effect, mechanical effect or chemotherapeutic drug) for cancer therapies, categorized and termed as "energy-converting nanomedicine," have arouse considerable concern due to their noninvasiveness, desirable tissue-penetration depth, and accurate modulation of therapeutic dose. This review summarizes the recent advances in the engineering of intelligent functional nanotherapeutics for energy-converting nanomedicine, including photo-based, radiation-based, ultrasound-based, magnetic field-based, microwave-based, electric field-based, and radiofrequency-based nanomedicines, which are enabled by external stimuli (light, radiation, ultrasound, magnetic field, microwave, electric field, and radiofrequency). Furthermore, biosafety issues of energy-converting nanomedicine related to future clinical translation are also addressed. Finally, the potential challenges and prospects of energy-converting nanomedicine for future clinical translation are discussed.

Synthesis and Biomedical Applications of Multifunctional Nanoparticles

The accumulated knowledge of nanoparticle (NP) synthesis for the last 30 years has enabled the development of functional NPs for biomedical applications. Especially, NPs with multifunctional capabilities are gaining popularity as the demand for versatile and efficient NP agents increases. Various combinations of functional materials are integrated to form multicomponent NPs with designed size, structure, and multifunctionality. Their use as diagnostic and/or therapeutic tools is demonstrated, suggesting their application potentials in healthcare and medical practice. Here, the recent achievements in the synthesis and biomedical applications of multifunctional NPs are summarized. Starting with a brief overview regarding the advances in NP synthesis and accompanying progress in nanobiotechnology, various components to construct the multifunctional NP agents, which include polymers and mesoporous, magnetic, catalytic, and semiconducting NPs, are discussed together with their overall integration forms, such as NP assembly, hollow/porous structures, or hybrid/doped systems. Following the explanation of the features that multifunctional NP agents can offer, an outlook and a brief comment regarding the future research directions are provided.

Nanoparticle-Mediated Acoustic Cavitation Enables High Intensity Focused Ultrasound Ablation Without Tissue Heating

While thermal ablation of various solid tumors has been demonstrated using high intensity focused ultrasound (HIFU), the therapeutic outcomes of this technique are still unsatisfactory because of common recurrence of thermally ablated cancers and treatment side effects due to the high ultrasound intensity and acoustic pressure requirements. More precise ablation of tumors can be achieved by generating cavitating bubbles in the tissue using shorter pulses with higher acoustic pressures, which induce mechanical damage rather than thermal. However, it has remained as a challenge to safely deliver the acoustic pressures required for mechanical ablation of solid tumors. Here, we report a method to achieve mechanical ablation at lower acoustic pressures by utilizing phospholipid-stabilized hydrophobic mesoporous silica nanoparticles (PL-hMSN). The PL-hMSNs act as seeds for nucleation of cavitation events and thus significantly reduce the peak negative pressures and spatial-average temporal-average HIFU intensities needed to achieve mechanical ablation. Substantial mechanical damage was observed in the red blood cell or tumor spheroid containing tissue mimicking phantoms at PL-hMSN concentrations as low as 10 μg mL^-1, after only 5 s of HIFU treatment with peak negative pressures ∼11 MPa and duty cycles ∼0.01%. Even the application of HIFU (peak negative pressure of 16.8 MPa and duty cycle of 0.017%) for 1 min in the presence of PL-hMSN (200 μg mL^-1) did not cause any detectable temperature increase in tissue-mimicking phantoms. In addition, the mechanical effects of cavitation promoted by PL-hMSNs were observed up to 0.5 mm from the center of the cavitation events. This method may thus also improve delivery of therapeutics or nanoparticles to tumor environments with limited macromolecular transport.

Targeted Nanomedicine to Treat Bone Metastasis

Bone metastases are common complications of solid tumors, particularly those of the prostate, breast, and lungs. Bone metastases can lead to painful and devastating skeletal-related events (SREs), such as pathological fractures and nerve compressions. Despite advances in treatment for cancers in general, options for bone metastases remain inadequate and generally palliative. Anticancer drugs (chemotherapy and radiopharmaceuticals) do not achieve therapeutic concentrations in the bone and are associated with dose-limiting side effects to healthy tissues. Nanomedicines, with their tunable characteristics, have the potential to improve drug targeting to bone metastases while decreasing side effects for their effective treatment. In this review, we present the current state of the art for nanomedicines to treat bone metastases. We also discuss new treatment modalities enhanced by nanomedicine and their effects on SREs and disease progression.

Controllable Nucleation of Cavitation from Plasmonic Gold Nanoparticles for Enhancing High Intensity Focused Ultrasound Applications

In this study, plasmonic gold nanoparticles were simultaneously exposed to pulsed near-infrared laser light and high intensity focused ultrasound (HIFU) for the controllable nucleation of cavitation in tissue-mimicking gel phantoms. This in vitro protocol was developed to demonstrate the feasibility of this approach, for both enhancement of imaging and therapeutic applications for cancer. The same apparatus can be used for both imaging and therapeutic applications by varying the exposure duration of the HIFU system. For short duration exposures (10 µs), broadband acoustic emissions were generated through the controlled nucleation of inertial cavitation around the gold nanoparticles. These emissions provide direct localization of nanoparticles. For future applications, these particles may be functionalized with molecular-targeting antibodies (e.g. anti-HER2 for breast cancer) and can provide precise localization of cancerous regions, complementing routine diagnostic ultrasound imaging. For continuous wave (CW) exposures, the cavitation activity was used to increase the localized heating from the HIFU exposures resulting in larger thermal damage in the gel phantoms. The acoustic emissions generated from inertial cavitation activity during these CW exposures was monitored using a passive cavitation detection (PCD) system to provide feedback of cavitation activity. Increased localized heating was only achieved through the unique combination of nanoparticles, laser light and HIFU. Further validation of this technique in pre-clinical models of cancer is necessary.

Influence of Magnetic Nanoparticles on the Focused Ultrasound Hyperthermia

Ultrasound hyperthermia is a medical treatment used to increase temperature of tissues. It can be used independently or as a supportive method for an anticancer treatment. The therapeutic efficacy of focused ultrasound hyperthermia can be improved using sonosensitizers, nanoparticles enhancing the attenuation and dissipation of acoustic energy. As sonosensitizers, we propose magnetic nanoparticles owing to their biodegradability, biocompatibility, and simple positioning in tissues using a magnetic field. Focused ultrasound hyperthermia studies were performed using tissue-mimicking phantoms. Temperature changes were measured at various ultrasound powers and distances from the center of the ultrasound focus. Specific absorption rate (SAR) values, describing the power deposition in the tissues during the hyperthermia treatment, were evaluated for the center of the focus point and for various distances from it. The results show that the addition of nanoparticles increases the SAR almost two times compared to that for the pure phantom. The highest SAR is obtained in the ultrasound focus; it decreases with the increase of the distance from the focus.

Heating Induced by Therapeutic Ultrasound in the Presence of Magnetic Nanoparticles

The efficiency of ultrasound hyperthermia for anti-cancer treatments such as radiotherapy or chemotherapy can be improved by using sonosensitizers, which are materials that enhance the attenuation and dissipation of acoustic energy. We propose the use of magnetic nanoparticles as sonosensitizers because of their biocompatibility, nontoxicity, and common use in several medical applications. A magnetic material was synthetized and then incorporated in the form of a magnetic fluid in agar tissue-mimicking phantoms. Ultrasound hyperthermia studies were conducted at various ultrasound frequencies and concentrations of magnetic nanoparticles in the phantoms. The theoretical modeling based on a heat transfer equation and the experimental results show good agreement and confirm that the temperature rise during ultrasound heating in tissue-mimicking phantoms doped with sonosensitizers is greater than that in a pure agar phantom. Furthermore, on the basis of Pennes' bio-heat equation, which takes into consideration the blood perfusion and metabolic heat, the thermal dose and lesion shapes after sonication were determined for a hypothetical tissue.