In Vivo Targeted, Responsive, and Synergistic Cancer Nanotheranostics by Magnetic Resonance Imaging-Guided Synergistic High-Intensity Focused Ultrasound Ablation and Chemotherapy

Research progress on ultrasound in bacteria-mediated tumor treatment

Bacteria-mediated tumor treatment (BMTT) has recently garnered significant attention as a promising avenue in tumor treatment. Despite the application of various strains in animal models and clinical trials, the effectiveness of BMTT has been hindered by its toxicity and inefficiency. In recent years, it has been explored that applying the biological effects of ultrasound could further improve the precision and effectiveness of BMTT. This review briefly introduces the challenges of BMTT and summarizes how the biological effects of ultrasound improve the efficacy and safety of BMTT in strategies involving genetic engineering, visualization and targeted delivery. The potential application and limitations of ultrasound in advancing BMTT controllable strategies are also discussed.

Application of high intensity focused ultrasound combined with nanomaterials in anti-tumor therapy

High intensity focused ultrasound (HIFU) has demonstrated its safety, efficacy and noninvasiveness in the ablation of solid tumor. However, its further application is limited by its inherent deficiencies, such as postoperative recurrence caused by incomplete ablation and excessive intensity affecting surrounding healthy tissues. Recent research has indicated that the integration of nanomaterials with HIFU exhibits a promising synergistic effect in tumor ablation. The concurrent utilization of nanomaterials with HIFU can help overcome the limitations of HIFU by improving targeting and ablation efficiency, expanding operation area, increasing operation accuracy, enhancing stability and bio-safety during the process. It also provides a platform for multi-therapy and multi-mode imaging guidance. The present review comprehensively expounds upon the synergistic mechanism between nanomaterials and HIFU, summarizes the research progress of nanomaterials as cavitation nuclei and drug carriers in combination with HIFU for tumor ablation. Furthermore, this review highlights the potential for further exploration in the development of novel nanomaterials that enhance the synergistic effect with HIFU on tumor ablation.

Progress in application of nanomedicines for enhancing cancer sono-immunotherapy

Cancer immunotherapy has significant potential as a cancer treatment since it boosts the immune system and prevents immune escape to get rid of or fight cancers. However, its clinical applicability is still limited because of the low response rate and immune-related side effects. Recently ultrasound has been shown to alter the tumor immune microenvironment, enhance the effectiveness of other antitumor therapies, and cause tumors to become more sensitive to immunotherapy, thus providing new insights into cancer treatment. Nanomedicines are also anticipated to have a positive impact on improving the immunological effects and enhancing ultrasound effect for cancer therapy. Therefore, designing effective nanomedicines enhanced ultrasound effect for augmenting sono-immunotherapy has been a pivot on anticancer therapy. In this review, the immunological impacts of various ultrasound therapeutic modalities, ultrasound parameters, and their underlying mechanisms are discussed. Moreover, we highlight the recent progress of nanomedicines synergistically enhancing sono-immunotherapy. Finally, we put forward opportunities and challenges on sono-immunotherapy.

US/PA/MR multimodal imaging-guided multifunctional genetically engineered bio-targeted synergistic agent for tumor therapy

Focused ultrasound ablation surgery (FUAS) is a minimally invasive treatment option that has been utilized in various tumors. However, its clinical advancement has been hindered by issues such as low safety and efficiency, single image guidance mode, and postoperative tumor residue. To address these limitations, this study aimed to develop a novel multi-functional gas-producing engineering bacteria biological targeting cooperative system. Pulse-focused ultrasound (PFUS) could adjust the ratio of thermal effect to non-thermal effect by adjusting the duty cycle, and improve the safety and effectiveness of treatment.The genetic modification of Escherichia coli (E.coli) involved the insertion of an acoustic reporter gene to encode gas vesicles (GVs), resulting in gas-producing E.coli (GVs-E.coli) capable of targeting tumor anoxia. GVs-E.coli colonized and proliferated within the tumor while the GVs facilitated ultrasound imaging and cooperative PFUS. Additionally, multifunctional cationic polyethyleneimine (PEI)-poly (lactic-co-glycolic acid) (PLGA) nanoparticles (PEI-PLGA/EPI/PFH@Fe3O4) containing superparamagnetic iron oxide (SPIO, Fe3O4), perfluorohexane (PFH), and epirubicin (EPI) were developed. These nanoparticles offered synergistic PFUS, supplementary chemotherapy, and multimodal imaging capabilities.GVs-E.coli effectively directed the PEI-PLGA/EPI/PFH@Fe3O4 to accumulate within the tumor target area by means of electrostatic adsorption, resulting in a synergistic therapeutic impact on tumor eradication.In conclusion, GVs-E.coli-mediated multi-functional nanoparticles can synergize with PFUS and chemotherapy to effectively treat tumors, overcoming the limitations of current FUAS therapy and improving safety and efficacy. This approach presents a promising new strategy for tumor therapy.

CD133-targeted multifunctional nanomicelles for dual-modality imaging and synergistic high-intensity focus ultrasound (HIFU) ablation on pancreatic cancer in nude mice

Pancreatic cancer is an aggressive and highly fatal malignant tumor. Recent studies have shown that cancer stem cells (CSCs) play an important role in resisting current therapeutic modalities. Furthermore, CD133 is highly expressed in CSCs. High-intensity focused ultrasound (HIFU) is a promising non-invasive therapeutic strategy for unresectable pancreatic cancers. In our study, we synthesized targeted CD133 organosilane nanomicelles by encapsulating perfluorohexane (PFH). The CD133 antibody on the surface could specifically bind to CD133-positive pancreatic cancer cells and selectively concentrate in pancreatic cancer tumor tissues. PFH was introduced to improve the ablation effect of HIFU due to its liquid-gas phase transition properties. By combining with the dorsal skinfold window chamber model (DSWC) of pancreatic cancer in nude mice, multiphoton fluorescence microscopy was used to evaluate the targeting effect of nanomicelles on pancreatic cancer tumor tissue. These multifunctional nanomicelles synergistically affected HIFU treatment of pancreatic cancer, providing an integrated research platform for diagnosing and treating pancreatic cancer with HIFU.

Ultrasound-Sensitive Intelligent Nanosystems: A Promising Strategy for the Treatment of Neurological Diseases

Neurological diseases are a major global health challenge, affecting hundreds of millions of people worldwide. Ultrasound therapy plays an irreplaceable role in the treatment of neurological diseases due to its noninvasive, highly focused, and strong tissue penetration capabilities. However, the complexity of brain and nervous system and the safety risks associated with prolonged exposure to ultrasound therapy severely limit the applicability of ultrasound therapy. Ultrasound-sensitive intelligent nanosystems (USINs) are a novel therapeutic strategy for neurological diseases that bring greater spatiotemporal controllability and improve safety to overcome these challenges. This review provides a detailed overview of therapeutic strategies and clinical advances of ultrasound in neurological diseases, focusing on the potential of USINs-based ultrasound in the treatment of neurological diseases. Based on the physical and chemical effects induced by ultrasound, rational design of USINs is a prerequisite for improving the efficacy of ultrasound therapy. Recent developments of ultrasound-sensitive nanocarriers and nanoagents are systemically reviewed. Finally, the challenges and developing prospects of USINs are discussed in depth, with a view to providing useful insights and guidance for efficient ultrasound treatment of neurological diseases.

Metal-Organic Framework-Mediated Synergistic Hypoxia-Activated Chemo-Immunotherapy Induced by High Intensity Focused Ultrasound for Enhanced Cancer Theranostics

High intensity focused ultrasound (HIFU) has attracted considerable attention as a noninvasive, efficient, and economic therapeutic modality for solid tumors. However, HIFU surgery has its intrinsic limitation in completely ablating tumors, leading to residual tumor tissue. Furthermore, the severely hypoxic environment ensuring after surgery can exacerbate the unrestricted proliferation and metabolism of residual tumor cells, leading to tumor recurrence and metastasis. To address these limitations, a versatile HIFU-specific metal-organic framework nanosystem (called ADMOFs) is developed by coordinating hypoxia-activated prodrug AQ4N, Mn2+, and DOX based on the postoperative response to changes in the tumor microenvironment. ADMOFs loaded with AQ4N/Mn2+ exhibited remarkable tumor-targeting behavior in vivo and enhanced photoacoustic/magnetic resonance imaging effects, enabling more accurate guidance for HIFU surgery. After surgery, the ADMOFs exploited the severely hypoxic tumor environment induced by HIFU, overcoming hypoxia-associated drug resistance, and inducing immunogenic cell death. Finally, it effectively inhibited tumor growth and eliminated lung metastasis. Transcriptome studies revealed that this strategy significantly up-regulated genes involved in apoptosis, cell cycle, and HIF-1 signaling pathway while downregulating genes related to tumor proliferation and metastasis. These findings suggest that combining hypoxia-activated chemo-immunotherapy with HIFU is a promising strategy for enhancing cancer theranostics.

Superparamagnetic Artificial Cells PLGA-Fe3O4 Micro/Nanocapsules for Cancer Targeted Delivery

Artificial cells have been extensively used in many fields, such as nanomedicine, biotherapy, blood substitutes, drug delivery, enzyme/gene therapy, cancer therapy, and the COVID-19 vaccine. The unique properties of superparamagnetic Fe3O4 nanoparticles have contributed to increased interest in using superparamagnetic artificial cells (PLGA-Fe3O4 micro/nanocapsules) for targeted therapy. In this review, the preparation methods of Fe3O4 NPs and superparamagnetic artificial cell PLGA-drug-Fe3O4 micro/nanocapsules are discussed. This review also focuses on the recent progress of superparamagnetic PLGA-drug-Fe3O4 micro/nanocapsules as targeted therapeutics. We shall concentrate on the use of superparamagnetic artificial cells in the form of PLGA-drug-Fe3O4 nanocapsules for magnetic hyperthermia/photothermal therapy and cancer therapies, including lung breast cancer and glioblastoma.

Recent development of pH-responsive theranostic nanoplatforms for magnetic resonance imaging-guided cancer therapy

The acidic characteristic of the tumor site is one of the most well-known features and provides a series of opportunities for cancer-specific theranostic strategies. In this regard, pH-responsive theranostic nanoplatforms that integrate diagnostic and therapeutic capabilities are highly developed. The fluidity of the tumor microenvironment (TME), with its temporal and spatial heterogeneities, makes noninvasive molecular magnetic resonance imaging (MRI) technology very desirable for imaging TME constituents and developing MRI-guided theranostic nanoplatforms for tumor-specific treatments. Therefore, various MRI-based theranostic strategies which employ assorted therapeutic modes have been drawn up for more efficient cancer therapy through the raised local concentration of therapeutic agents in pathological tissues. In this review, we summarize the pH-responsive mechanisms of organic components (including polymers, biological molecules, and organosilicas) as well as inorganic components (including metal coordination compounds, metal oxides, and metal salts) of theranostic nanoplatforms. Furthermore, we review the designs and applications of pH-responsive theranostic nanoplatforms for the diagnosis and treatment of cancer. In addition, the challenges and prospects in developing theranostic nanoplatforms with pH-responsiveness for cancer diagnosis and therapy are discussed.

Integrated pipeline for ultrasensitive protein detection in cancer nanomedicine

Although nanotechnologies have attractive attributes in cancer therapy, their full potential has yet to be realized due to challenges in their translation to clinical settings. The evaluation of cancer nanomedicine efficacy in preclinical in vivo studies is limited to tumor size and animal survival metrics, which do not provide adequate understanding of the nanomedicine's mechanism of action. To address this, we have developed an integrated pipeline called nanoSimoa that combines an ultrasensitive protein detection technique (Simoa) with cancer nanomedicine. As a proof-of concept, we assessed the therapeutic efficacy of an ultrasound-responsive mesoporous silica nanoparticle (MSN) drug delivery system on OVCAR-3 ovarian cancer cells using CCK-8 assays to evaluate cell viability and Simoa assays to measure IL-6 protein levels. The results demonstrated significant reductions in both IL-6 levels and cell viability following nanomedicine treatment. In addition, a Ras Simoa assay (limit of detection: 0.12 pM) was developed to detect and quantify Ras protein levels in OVCAR-3 cells, which are undetectable by commercial enzyme-linked immunosorbent assays (ELISA). These results suggest that nanoSimoa has the potential to guide the development of cancer nanomedicines and predict their behavior in vivo, making it a valuable tool for preclinical testing and accelerating the development of precision medicine if its generalizability is confirmed.

Tumor microenvironment remodeling via targeted depletion of M2-like tumor-associated macrophages for cancer immunotherapy

M2-like tumor-associated macrophages (TAMs) typically exhibit numerous tumor-promoting properties. Reducing the abundance of M2-like TAMs would shed light on the relief of immunosuppressive tumor microenvironment (TME), activation of the host immune system, infiltration of CD8⁺ T cells into the TME and restoring the function of the infiltrating T cells, which collectively inhibits tumor growth. Therefore, targeted depletion of M2-like TAMs can be a promising immunotherapy approach. In this study, we rationally constructed an M2-like TAMs-targeted nanoliposome, which encapsulates zoledronic acid (ZA) in the core, loads hematoporphyrin monomethyl ether (HMME, a typical sonosensitizer) in the lipid bilayer, and modifies M2pep peptide (the targeting unit) on the surface (designated as M-H@lip-ZA). Our aim is to validate the effectiveness of M-H@lip-ZA nanoliposomes to remodel TME via targeted depletion of M2-like TAMs for cancer immunotherapy. Through the M2pep peptide, M-H@lip-ZA can be efficiently delivered to M2-like TAMs. In the meantime, reactive oxygen species (ROS) resulting from sonodynamic therapy (SDT), together with inner ZA that shows high affinity and cytotoxicity to TAMs, can effectively deplete M2-like TAMs and remodel TME (normalize tumor vasculatures, strengthen intertumoral perfusion, ease tumor hypoxia, increase immune-promoting cytokines and decrease immunosuppressive cytokines). The tumor growth can be effectively inhibited. This work proposed a new paradigm for cancer immunotherapy via targeted depletion of M2-like TAMs. STATEMENT OF SIGNIFICANCE: • M2-like TAMs-targeted nanoliposome (M-H@lip-ZA) was designed and prepared. • Sonodynamic therapy (SDT), together with zoledronic acid (ZA) that shows high affinity and cytotoxicity to tumor-associated macrophages (TAMs), can effectively deplete M2-like TAMs. Subsequently, immune-promoting tumor microenvironment (TME) can be formed, which includes normalized tumor vasculatures, enhanced intertumoral perfusion, relieved tumor hypoxia, increased immune-promoting cytokines, and decreased immunosuppressive cytokines. • The targeted depletion of M2-like TAMs is a promising cancer immunotherapy approach.

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.

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

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

Novel combination strategy of high intensity focused ultrasound (HIFU) and checkpoint blockade boosted by bioinspired and oxygen-supplied nanoprobe for multimodal imaging-guided cancer therapy

BACKGROUND

High-intensity focused ultrasound (HIFU) has shown considerable promise in treating solid tumors, but its ultrasonic energy is easily attenuated, resulting in insufficient energy accumulation in the target area. Moreover, HIFU ablation alone may inevitably lead to the presence of residual tumors, which may cause tumor recurrence and metastasis. Here, we describe a synergistic regimen combining HIFU facilitation with immunomodulation based on a novel oxygen-carrying biomimetic perfluorocarbon nanoparticle (M@P-SOP) to stimulate immunogenic cell death in tumor cells while alleviating immune suppression tumor microenvironment.

METHODS

M@P-SOP was prepared by double emulsion and film extrusion method. The anticancer and antimetastatic effects of M@P-SOP were evaluated on a preclinical transplanted 4T1 tumor model by combining HIFU and immunotherapy. Flow cytometry and immunofluorescence were used to clarify the potential mechanism of HIFU+M@P-SOP and their role in anti-programmed death ligand-1 (PD-L1) therapy.

RESULTS

Guided by photoacoustic/MR/ultrasound (US) multimodal imaging, M@P-SOP was abundantly enriched in tumor, which greatly enhanced HIFU's killing of tumor tissue in situ, induced stronger tumor immunogenic cell death, stimulated dendritic cell maturation and activated CD8⁺ T cells. At the same time, M@P-SOP released oxygen to alleviate the tumor hypoxic environment, repolarizing the protumor M2-type macrophages into antitumor M1-type. With concurrent anti-PD-L1 treatment, the antitumor immune response was further amplified to the whole body, and the growth of mimic distant tumor was effectively suppressed.

CONCLUSIONS

Our findings offer a highly promising HIFU synergist for effectively ameliorating acoustic and hypoxia environment, eventually inhibiting tumor growth and metastasis by stimulating host's antitumor immunity under HIFU ablation, especially in synergizing with PD-L1 antibody immunotherapy.

Research progress of stimulus-responsive antibacterial materials for bone infection

Infection is one of the most serious complications harmful to human health, which brings a huge burden to human health. Bone infection is one of the most common and serious complications of fracture and orthopaedic surgery. Antibacterial treatment is the premise of bone defect healing. Among all the antibacterial strategies, irritant antibacterial materials have unique advantages and the ability of targeted therapy. In this review, we focus on the research progress of irritating materials, the development of antibacterial materials and their advantages and disadvantages potential applications in bone infection.

A Synergistic and Efficient Thrombolytic Nanoplatform: A Mechanical Method of Blasting Combined with Thrombolytic Drugs

BACKGROUND AND OBJECTIVE

Thrombosis is a common disease that poses a great threat to life and health. Most thrombolytic effects of traditional treatments or nanomedicine are not efficient or safe enough. Therefore, we designed a nanoparticle (NP) with a combination of a phase transition material and thrombolytic drugs for efficient and safe thrombolysis.

METHODS

A thrombus fibrin-targeted and phase transition NP was designed and contained perfluorohexane (PFH) and the thrombolytic drug rtPA core, with CREKA polypeptides attached to the shell of the PLGA NPs. Characterization of the phase transition and ultrasound imaging of the NPs was carried out under low-intensity focused ultrasound (LIFU). LIFU-responsive drug release in vitro was also explored. Under the synergistic effect of PFH and rtPA, the efficient thrombolysis ability of the NPs was studied in vitro and in vivo. In vivo monitoring of thrombosis and biosafety were also verified.

RESULTS

The PPrC NPs had good ultrasound imaging ability under LIFU irradiation and were related to the phase transition characteristics of the NPs. CREKA polypeptides can effectively increase the aggregation of the NPs on thrombi. Under static and dynamic conditions in vitro, the "liquid to gas" transformation effect of PFH can perform the destruction function of the excavator at the thrombus site and promote the specific release of rtPA, and the subsequent rtPA drug thrombolysis can further fully dissolve the thrombus. In vivo experiments showed that the NPs can monitor the formation of thrombi and have good thrombolytic effects, with significantly reduced bleeding side effects. The biochemical indexes of the rats were within normal limits after treatment.

CONCLUSION

PPrC NPs loaded with PFH and rtPA combining a mechanical way of blasting with thrombolytic drugs may be a promising new and reliable approach for thrombus monitoring and treatment.

Tailoring Polymer-Based Nanoassemblies for Stimuli-Responsive Theranostic Applications

Polymer assemblies on the nanoscale represent a powerful toolbox for the design of theranostic systems when combined with both therapeutic compounds and diagnostic reporting ones. Here, recent advances in the design of theranostic systems for various diseases, containing-in their architecture-either polymers or polymer assemblies as one of the building blocks are presented. This review encompasses the general principles of polymer self-assembly, from the production of adequate copolymers up to supramolecular assemblies with theranostic functionality. Such polymer nanoassemblies can be further tailored through the incorporation of inorganic nanoparticles to endow them with multifunctional therapeutic and/or diagnostic features. Systems that change their architecture or properties in the presence of stimuli are selected, as responsivity to changes in the environment is a key factor for enhancing efficiency. Such theranostic systems are based on the intrinsic properties of copolymers or one of the other components. In addition, systems with a more complex architecture, such as multicompartments, are presented. Selected systems indicate the advantages of such theranostic approaches and provide a basis for further developments in the field.

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.

Construction of magnetic drug delivery system and its potential application in tumor theranostics

Magnetic nanoparticles(NPs) are characterized by a rich variety of properties. Because of their excellent physical and chemical properties, they have come to the fore in biomedicine and other fields. The magnetic NPs were extensively studied in magnetic separation of cells, targeted drug delivery, tumor hyperthermia, chemo-photothermal therapy, magnetic resonance imaging (MRI) and other biomedical fields. Magnetic NPs are increasingly used in magnetic resonance imaging (MRI) based on their inherent magnetic targeting, superparamagnetic enzyme-like catalytic properties and nanoscale size. Poly(lactic-co-glycolic acid) (PLGA) is a promising biodegradable material approved by FDA and EU for drug delivery. Currently, PLGA-based magnetic nano-drug delivery systems have attracted the attention of researchers. Herein, we achieved the effective encapsulation of sized-controlled polyethylene glycol-3,4-dihydroxy benzyl-amine-coated superparamagnetic iron oxide nanoparticles (SPIO NPs) and euphorbiasteroid into PLGA nanospheres via a modified multiple emulsion solvent evaporation method (W₁/O₂/W₂). NPs with narrow size distribution and acceptable magnetic properties were developed that are very useful for applications involving cancer therapy and MRI. Furthermore, SPIO-PLGA NPs enhanced the MRI T₂ relaxation properties of tumor sites.The prepared SPIO NPs and magnetic PLGA nanospheres can be promising magnetic drug delivery systems for tumor theranostics. This study has successfully constructed a tumor-targeting and magnetic-targeting smart nanocarrier with enhanced permeability and retention, multimodal anti-cancer therapeutics and biodegradability, which could be a hopeful candidate for anti-tumor therapy in the future.

Low-Power Magnetic Resonance-Guided Focused Ultrasound Tumor Ablation upon Controlled Accumulation of Magnetic Nanoparticles by Cascade-Activated DNA Cross-Linkers

Magnetic resonance-guided focused ultrasound (MRgFUS) is a promising non-invasive surgical technique with spatial specificity and minimal off-target effects. Despite the expanding clinical applications, the major obstacles associated with MRgFUS still lie in low magnetic resonance imaging (MRI) sensitivity and safety issues. High ultrasound power is required to resist the energy attenuation during the delivery to the tumor site and may cause damage to the surrounding healthy tissues. Herein, a surface modification strategy is developed to simultaneously strengthen MRI and ultrasound ablation of MRgFUS by prolonging Fe₃O₄ nanoparticles' blood circulation and tumor-environment-triggered accumulation and retention at the tumor site. Specifically, reactive oxygen species-labile methoxy polyethylene glycol and pH-responsive DNA cross-linkers are modified on the surface of Fe₃O₄ nanoparticles, which can transform nanoparticles into aggregations through the cascade responsive reactions at the tumor site. Notably, DNA is selected as the pH-responsive cross-linker because of its superior biocompatibility as well as the fast and sensitive response to the weak acidity of 6.5-6.8, corresponding to the extracellular pH of tumor tissues. Due to the significantly enhanced delivery and retention amount of Fe₃O₄ nanoparticles at the tumor site, the MRI sensitivity was enhanced by 1.7-fold. In addition, the ultrasound power was lowered by 35% to reach a sufficient thermal ablation effect. Overall, this investigation demonstrates a feasible resolution to promote the MRgFUS treatment by enhancing the therapeutic efficacy and reducing the side effects, which will be helpful to guide the clinical practice in the future.

Novel Magnetic Elastic Phase-Change Nanodroplets as Dual Mode Contrast Agent for Ultrasound and Magnetic Resonance Imaging

Recently, dual-mode imaging systems merging magnetic resonance imaging (MRI) and ultrasound (US) have been developed. Designing a dual-mode contrast agent is complex due to different mechanisms of enhancement. Herein, we describe novel phase change nanodroplets (PCNDs) with perfluoropentane encapsulated in a pre-polyglycerol sebacate (pre-PGS) shell loaded with polyethylene glycol (PEG)-coated iron oxide nanoparticles as having a dual-mode contrast agent effect. Iron oxide nanoparticles were prepared via the chemical co-precipitation method and PCNDs were prepared via the solvent displacement technique. PCNDs showed excellent enhancement in the in vitro US much more than Sonovue^® microbubbles. Furthermore, they caused a susceptibility effect resulting in a reduction of signal intensity on MRI. An increase in the concentration of nanoparticles caused an increase in the MR contrast effect but a reduction in US intensity. The concentration of nanoparticles in a shell of PCNDs was optimized to obtain a dual-mode contrast effect. Biocompatibility, hemocompatibility, and immunogenicity assays showed that PCNDs were safe and non-immunogenic. Another finding was the dual-mode potential of unloaded PCNDs as T1 MR and US contrast agents. Results suggest the excellent potential of these PCNDs for use as dual-mode contrast agents for both MRI and US.

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.

Update of ultrasound-assembling fabrication and biomedical applications for heterogeneous polymer composites

As a power-driving approach, ultrasound irradiation is very appealing to the preparation or modification of new materials. In the review, we overviewed the latest development of ultrasound-mediated effects or reactions in polymer composites, and demonstrated its unique and powerful aspects on the polymerization or aggregation. The review generalized the different categories of heterogeneous polymer composites by defining the constituents, and described the shapes, sizes and basic properties of various purpose-specific or site-specific products. Importantly, the review paid more attention to the main biomedicine applications of heterogeneous polymer composites, such as drug or bioactive substance entrapment, delivery, release, imaging, and therapy, and emphasized many advantages of ultrasound-assembling approaches and heterogeneous polymer composites in biology and medicine fields. In addition, the review also indicated the prospective challenges of heterogeneous polymer composites both in ultrasound-assembling designs and in biomedical applications.

Complementary Acoustic Metamaterial for Penetrating Aberration Layers

Impedance-matched acoustic materials were developed to improve ultrasound penetration through the aberration layer. The traditional ultrasound layer matching material is called a couplant, which can only enhance ultrasound transmission to soft biological media such as the cartilage and muscle but cannot penetrate hard media such as the bone. Here, we propose a phase-modulated complementary acoustic metamaterial based on the principle of impedance matching, which enables ultrasound to penetrate the bone, and use the equivalent parameter technology of acoustic metamaterials for parameter design. Ultrasonic layer adjustment is performed through 3D printing and corrects bone aberrations. Several configurations were investigated through numerical simulations and experiments in non-reflecting tanks. Specifically, the bone matching layer can be optimally designed for a specific bone thickness and a specific operating frequency of the ultrasound probe, thereby amplifying the ultrasound to penetrate the matching layer and bone. The experimental and simulation results show that the proposed acoustic metamaterial can improve the transmission efficiency of ultrasound through the aberration layer.

Ultrasound and Nanomedicine for Cancer-Targeted Drug Delivery: Screening, Cellular Mechanisms and Therapeutic Opportunities

Cancer is a disease characterized by abnormal cell growth. According to a report published by the World Health Organization (WHO), cancer is the second leading cause of death globally, responsible for an estimated 9.6 million deaths in 2018. It should be noted that ultrasound is already widely used as a diagnostic procedure for detecting tumorigenesis. In addition, ultrasound energy can also be utilized effectively for treating cancer. By filling the interior of lipospheres with gas molecules, these particles can serve both as contrast agents for ultrasonic imaging and as delivery systems for drugs such as microbubbles and nanobubbles. Therefore, this review aims to describe the nanoparticle-assisted drug delivery system and how it can enhance image analysis and biomedicine. The formation characteristics of nanoparticles indicate that they will accumulate at the tumor site upon ultrasonic imaging, in accordance with their modification characteristics. As a result of changing the accumulation of materials, it is possible to examine the results by comparing images of other tumor cell lines. It is also possible to investigate ultrasound images for evidence of cellular effects. In combination with a precision ultrasound imaging system, drug-carrying lipospheres can precisely track tumor tissue and deliver drugs to tumor cells to enhance the ability of this nanocomposite to treat cancer.

Multifunctional Theranostic Nanoparticles for Enhanced Tumor Targeted Imaging and Synergistic FUS/Chemotherapy on Murine 4T1 Breast Cancer Cell

Purpose

Triple negative breast cancer (TNBC) is challenging for effective remission due to its very aggressive, extremely metastatic and resistant to conventional chemotherapy. Herein, a multifunctional theranostic nanoparticle was fabricated to enhance tumor targeted imaging and promote focused ultrasound (FUS) ablation and chemotherapy and sonodynamic therapy (SDT). A multi-modal synergistic therapy can improve the therapeutic efficacy and prognosis of TNBC.

Methods

AS1411 aptamer modified PEG@PLGA nanoparticles encapsulated with perfluorohexane (PFH) and anti-cancer drug doxorubicin (DOX) were constructed (AS1411-DOX/PFH-PEG@PLGA) to enhance tumor targeted imaging to guide ablation and synergistic effect of FUS/chemotherapy. FUS was utilized to trigger the co-release of doxorubicin and simultaneously PFH phase transition and activate DOX for SDT effect. The physicochemical, phase-changeable imaging capability, biosafety of nanoparticles and multi-mode synergistic effects on growth of TNBC were thoroughly evaluated in vivo and in vitro.

Results

The synthesized AS1411-DOX/PFH-PEG@PLGA (A-DPPs) nanoparticles are uniformly round with an average diameter of 306.03 ± 5.35 nm and the zeta potential of −4.05 ± 0.13 mV, displaying high biosafety and FUS-responsive drug release in vitro and in vivo. AS1411 modified NPs specifically bind to 4T1 cells and elevate the ultrasound contrast agent (UCA) image contrast intensity via PFH phase-transition after FUS exposure. Moreover, the combined treatment of A-DPPs nanoparticles with FUS exhibited significantly higher apoptosis rate, stronger inhibitory effect on 4T1 cell invasion in vitro, induced more reactive oxygen species (ROS), and enhanced anti-tumor effect compared to a single therapy (p < 0.05). Additionally, the joint strategy resulted in more intense cavitation effect and larger ablated areas and reduced energy efficiency factor (EEF) both in vitro and in vivo.

Conclusion

The multifunctional AS1411-DOX/PFH-PEG@PLGA nanoparticles can perform as a marvelous synergistic agent for enhanced FUS/chemotherapy, promote real-time contrast enhanced US imaging and improve the therapeutic efficacy and prognosis of TNBC.

Magnetic Nanoparticle-Mediated Heating for Biomedical Applications

Magnetic nanoparticles, especially superparamagnetic nanoparticles (SPIONs), have attracted tremendous attention for various biomedical applications. Facile synthesis and functionalization together with easy control of the size and shape of SPIONS to customize their unique properties, have made it possible to develop different types of SPIONs tailored for diverse functions/applications. More recently, considerable attention has been paid to the thermal effect of SPIONs for the treatment of diseases like cancer and for nanowarming of cryopreserved/banked cells, tissues, and organs. In this mini-review, recent advances on the magnetic heating effect of SPIONs for magnetothermal therapy and enhancement of cryopreservation of cells, tissues, and organs, are discussed, together with the non-magnetic heating effect (i.e., high Intensity focused ultrasound or HIFU-activated heating) of SPIONs for cancer therapy. Furthermore, challenges facing the use of magnetic nanoparticles in these biomedical applications are presented.

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...

Synergic fabrication of pembrolizumab loaded doxorubicin incorporating microbubbles delivery for ultrasound contrast agents mediated anti-proliferation and apoptosis

This study evaluated pembrolizumab-conjugated, doxorubicin (DOX)-loaded microbubbles (PDMs) in combination with ultrasound (US) as molecular imaging agents for early diagnosis of B cell lymphomas, and as a targeted drug delivery system. Pembrolizumab, a monoclonal CD20 antibody, was attached to the surfaces of DOX-loaded microbubbles. PDM binding to B cell lymphoma cells was assessed using immunofluorescence. The cytotoxic effects of PDMs in combination with ultrasound (PDMs + US) were evaluated in vitro in CD20+ and CD20- cell lines, and its antitumor activities were assessed in Raji (CD20+) and Jurkat (CD20-) lymphoma cell-grafted mice. PDMs specifically bound to CD20+ cells in vitro and in vivo. Contrast enhancement was monitored in vivo via US. PDM peak intensities and contrast enhancement durations were higher in Raji than in Jurkat cell-grafted mice (p < 0.05). PDMs + US treatment resulted in improved antitumor effects and reduced systemic toxicity in Raji cell-grafted mice compared with other treatments (p < .05). Our results showed that PDMs + US enhanced tumor targeting, reduced systemic toxicity, and inhibited CD20+ B cell lymphoma growth in vivo. Targeted PDMs could be employed as US molecular imaging agents for early diagnosis, and are an effective targeted drug delivery system in combination with US for CD20+ B cell malignancy treatment.

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.

Scaffold 3D-Printed from Metallic Nanoparticles-Containing Ink Simultaneously Eradicates Tumor and Repairs Tumor-Associated Bone Defects

Bone metastasis occurs in about 70% of breast cancer patients. The surgical resection of metastatic tumors often leads to bone erosion and destruction, which greatly hinders the treatment and prognosis of breast cancer patients with bone metastasis. Herein, a bifunctional scaffold 3D-printed from nanoink is fabricated to simultaneously eliminate the tumor cells and repair the tumor-associated bone defects. The metallic polydopamine (PDA) nanoparticles (FeMg-NPs) may effectively load and sustainably release the metal ions Fe³⁺ and Mg²⁺ in situ. Fe³⁺ exerts a chemodynamic therapy to synergize with the photothermal therapy induced by PDA with effective photothermal conversion under NIR laser, which efficiently eliminates the bone-metastatic tumor. Meanwhile, the sustained release of osteoinductive Mg²⁺ from the bony porous 3D scaffold enhances the new bone formation in the bone defects. Taken together, the implantation of scaffold (FeMg-SC) 3D-printed from the FeMg-NPs-containing nanoink provides a novel strategy to simultaneously eradicate bone-metastatic tumor and repair the tumor-associated bone defects.

Smart magnetic resonance imaging-based theranostics for cancer

Smart theranostics are dynamic platforms that integrate multiple functions, including at least imaging, therapy, and responsiveness, in a single agent. This review showcases a variety of responsive theranostic agents developed specifically for magnetic resonance imaging (MRI), due to the privileged position this non-invasive, non-ionising imaging modality continues to hold within the clinical imaging field. Different MRI smart theranostic designs have been devised in the search for more efficient cancer therapy, and improved diagnostic efficiency, through the increase of the local concentration of therapeutic effectors and MRI signal intensity in pathological tissues. This review explores novel small-molecule and nanosized MRI theranostic agents for cancer that exhibit responsiveness to endogenous (change in pH, redox environment, or enzymes) or exogenous (temperature, ultrasound, or light) stimuli. The challenges and obstacles in the design and in vivo application of responsive theranostics are also discussed to guide future research in this interdisciplinary field towards more controllable, efficient, and diagnostically relevant smart theranostics agents.

Nanotherapeutics and nanotheragnostics for cancers: properties, pharmacokinetics, biopharmaceutics, and biosafety

With the worldwide increasing rate of chronic diseases, such as cancer, the development of novel techniques to improve the efficacy of therapeutic agents is highly demanded. Nanoparticles are especially well suited to encapsulate drugs and other therapeutic agents, bringing additional advantages, such as less frequent dosage requirements, reduced side effects due to specific targeting, and therefore increased patient compliance. However, with the increasing use of nanoparticles and their recent launch on the pharmaceutical market it is important to achieve high quality control of these advanced systems. In this review, we discuss the properties of different nanoparticles, the pharmacokinetics, the biosafety issues of concern, and conclude with novel nanotherapeutics and nanotheragnostics for cancer drug delivery.

Therapeutic oxygen delivery by perfluorocarbon-based colloids

After the protocol-related indecisive clinical trial of Oxygent, a perfluorooctylbromide/phospholipid nanoemulsion, in cardiac surgery, that often unduly assigned the observed untoward effects to the product, the development of perfluorocarbon (PFC)-based O₂ nanoemulsions ("blood substitutes") has come to a low. Yet, significant further demonstrations of PFC O₂-delivery efficacy have continuously been reported, such as relief of hypoxia after myocardial infarction or stroke; protection of vital organs during surgery; potentiation of O₂-dependent cancer therapies, including radio-, photodynamic-, chemo- and immunotherapies; regeneration of damaged nerve, bone or cartilage; preservation of organ grafts destined for transplantation; and control of gas supply in tissue engineering and biotechnological productions. PFC colloids capable of augmenting O₂ delivery include primarily injectable PFC nanoemulsions, microbubbles and phase-shift nanoemulsions. Careful selection of PFC and other colloid components is critical. The basics of O₂ delivery by PFC nanoemulsions will be briefly reminded. Improved knowledge of O₂ delivery mechanisms has been acquired. Advanced, size-adjustable O₂-delivering nanoemulsions have been designed that have extended room-temperature shelf-stability. Alternate O₂ delivery options are being investigated that rely on injectable PFC-stabilized microbubbles or phase-shift PFC nanoemulsions. The latter combine prolonged circulation in the vasculature, capacity for penetrating tumor tissues, and acute responsiveness to ultrasound and other external stimuli. Progress in microbubble and phase-shift emulsion engineering, control of phase-shift activation (vaporization), understanding and control of bubble/ultrasound/tissue interactions is discussed. Control of the phase-shift event and of microbubble size require utmost attention. Further PFC-based colloidal systems, including polymeric micelles, PFC-loaded organic or inorganic nanoparticles and scaffolds, have been devised that also carry substantial amounts of O₂. Local, on-demand O₂ delivery can be triggered by external stimuli, including focused ultrasound irradiation or tumor microenvironment. PFC colloid functionalization and targeting can help adjust their properties for specific indications, augment their efficacy, improve safety profiles, and expand the range of their indications. Many new medical and biotechnological applications involving fluorinated colloids are being assessed, including in the clinic. Further uses of PFC-based colloidal nanotherapeutics will be briefly mentioned that concern contrast diagnostic imaging, including molecular imaging and immune cell tracking; controlled delivery of therapeutic energy, as for noninvasive surgical ablation and sonothrombolysis; and delivery of drugs and genes, including across the blood-brain barrier. Even when the fluorinated colloids investigated are designed for other purposes than O₂ supply, they will inevitably also carry and deliver a certain amount of O₂, and may thus be considered for O₂ delivery or co-delivery applications. Conversely, O₂-carrying PFC nanoemulsions possess by nature a unique aptitude for ¹⁹F MR imaging, and hence, cell tracking, while PFC-stabilized microbubbles are ideal resonators for ultrasound contrast imaging and can undergo precise manipulation and on-demand destruction by ultrasound waves, thereby opening multiple theranostic opportunities.

A convergent synthetic platform for polymeric nanoparticle for the treatment of combination colorectal cancer therapy

In biomaterials and drug delivery, the development of polymeric therapies capable of the synchronized release of several therapeutic agents remains an important challenge. In this article, we describe the development of polymeric nanoparticles (PNPs) with precise molar ratios of Curcumin (CUR) and Methotrexate (MEX). The highly symmetric synthetic approach allows for the development of novel NPs-based combination therapeutic strategies for colorectal cancer. The fabricated CUR/MEX@PNPs were confirmed by transmission microscopy (TEM) and the size and polydispersity index were assessed through the dynamic light scattering (DLS). CUR and MEX were released slowly from the drug delivery without any burst impact. Furthermore, CUR/MEX@PNPs exhibited dose-responsive cytotoxic effects in CL40 and SW1417 cells, with a greater cell death ratio than that of free drugs. The drugs-loaded polymeric nanomaterials were more easily taken up by cancer cells in vitro, according to the cellular uptake analysis. The apoptotic features were confirmed by various fluorescence staining assay. The results of the fluorescent assay reveal that the nanomaterials remarkably induce apoptosis in colorectal cancer cells. Further, the apoptosis cell death mechanism was displayed that these nanomaterials significantly induce apoptosis in the targeted cancer cells. Overall, the current investigation confirmed that CUR/MEX@PNPs could be used to successfully combat colorectal cancers in the immediate future.HighlightsWe have developed the Curcumin (CUR) and Methotrexate (MEX) encapsulated polymeric nanoparticles (CUR/MEX@PNPs).CUR/MEX@PNPs confirmed by the various analytical methods.CUR/MEX@PNPs enhanced the in vitro proliferation against the colorectal cancer cells.Biochemical analysis results reveals that CUR/MEX@PNPs induce apoptosis.The apoptosis was confirmed by Annexin-V-FITC and PI for flow cytometry.

Phase-changeable nanoparticle-mediated energy conversion promotes highly efficient high-intensity focused ultrasound ablation

This review describes how phase-changeable nanoparticles enable highly efficient high-intensity focused ultrasound ablation (HIFU). HIFU is effective in the clinical treatment of solid malignant tumors. However, it has intrinsic disadvantages for treating some deep lesions, such as damage to surrounding normal tissues. When phase-changeable nanoparticles are used in HIFU treatment, they could serve as good synergistic agents because they are transported in the blood and permeated and accumulated effectively in tissues. HIFU's thermal effects can trigger nanoparticles to undergo a special phase transition, thus enhancing HIFU ablation efficiency. Nanoparticles can also carry anticancer agents and release them in the targeted area to achieve chemo-synergistic therapy response. Although the formation of nanoparticles is complicated and HIFU applications are still in an early stage, the potential for their use in synergy with HIFU treatment shows promising results.

Bifidobacterium bifidum-Mediated Specific Delivery of Nanoparticles for Tumor Therapy

Purpose

Hypoxia is considered to be obstructive to tumor treatment, but the reduced oxygen surroundings provide a suitable habitat for Bifidobacterium bifidum (BF) to colonize. The anaerobe BF selectively colonizes into tumors following systemic injection due to its preference for the hypoxia in the tumor cores. Therefore, BF may be a potential targeting agent which could be used effectively in tumor treatment. We aimed to determine whether a novel BF-mediated strategy, that was designed to deliver AP-PFH/PLGA NPs (aptamers CCFM641-5-functionalized Perfluorohexane (PFH) loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles) by aptamer-directed approach into solid tumor based on the tumor-targeting ability of BF, could improve efficiency of high intensity focused ultrasound (HIFU) treatment of breast cancer.

Methods

We synthesized AP-PFH/PLGA NPs using double emulsion method and carbodiimide method. Then, we evaluated targeting ability of AP-PFH/PLGA NPs to BF in vivo. Finally, we studied the efficacy of HIFU ablation based on BF plus AP-PFH/PLGA NPs (BF-mediated HIFU ablation) in tumor.

Results

The elaborately designed AP-PFH/PLGA NPs can target BF colonized in tumor to achieve high tumor accumulation, which can significantly enhance HIFU therapeutic efficiency. We also found that, compared with traditional chemotherapy, this therapy not only inhibits tumor growth, but also significantly prolongs the survival time of mice. More importantly, this treatment strategy has no obvious side effects.

Conclusion

We successfully established a novel therapy method, BF-mediated HIFU ablation, which provides an excellent platform for highly efficient and non-invasive therapy of tumor.

Nanoparticle-Assisted Sonosensitizers and Their Biomedical Applications

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

[Preparation of doxorubicin-loaded metallic organic nanoparticles and their effect for enhancing efficacy of high-intensity focused ultrasound therapy in tumor-bearing mice]

OBJECTIVE

To prepare metallic organic nanoparticles that produce synergistic effect in high-intensity focused ultrasound (HIFU) therapy of tumors.

OBJECTIVE

Glucose oxidase (GOD), MnO₂, ferric iron (Fe³⁺) and doxorubicin (DOX) were self-assembled by physical adsorption with previously prepared manganese dioxide (MnO₂) nanoparticles to obtain GOD-MnO₂-Fe³⁺-DOX nanoparticles (GMFD NPs). HepG2 tumor-bearing nude mouse models were given intravenous injections of normal saline or GMFD NPs followed 4 h later by HIFU at the acoustic power of 90 W with a total treatment time of 3 s. The changes of tumor gray value before and after HIFU irradiation were observed and 24 h after HIFU irradiation, coagulation necrosis in the tumor tissues was examined; the histological changes of the tumor tissues were observed with HE staining.

OBJECTIVE

We successfully prepared GMFD NPs, which had an average particle size of 131.23±0.84 nm with a surface potential of 21.87±1.72 mV. GMFD NPs, with a drug loading rate of 40.18%, was capable of releasing more than 77.2% of the loaded DOX within 4 h in acidic environment. In the tumor-bearing mouse models, HIFU irradiation following GMFD NP injection, as compared with saline injection, resulted in significantly enhanced gray value of the tumor (25.5±4.5 vs 18.7±3.9, P=0.04) and greater volume of coagulation necrosis (105.80 ± 1.21 mm³ vs 38.02 ± 0.34 mm³). The energy efficiency factor (EEF) was significantly lower in GMFD NPs group than in saline group (1.79 vs 4.97, P < 0.001).

OBJECTIVE

GMFD NPs prepared in this study can enhance tumor ablation efficacy of HIFU and release DOX for further treatment of the residual tumor tissue in mice.

Glutathione-Activated NO-/ROS-Generation Nanoparticles to Modulate the Tumor Hypoxic Microenvironment for Enhancing the Effect of HIFU-Combined Chemotherapy

The combination of high-intensity focused ultrasound (HIFU) and chemotherapy has promising potential in the synergistic treatment of various types of solid tumors. However, the clinical efficacy of HIFU in combination chemotherapy is often impeded by the pre-existing hypoxia tumor microenvironment-induced multidrug resistance (MDR). Therefore, it is imperative for HIFU combined with chemotherapy to overcome MDR by improving the tumor hypoxic microenvironment. Hence, we developed highly stable nanoparticles (P@BDOX/β-lapachone-NO-NPs) with intracellular nitric oxide (NO)- and reactive oxygen species (ROS)-generating capabilities at the tumor site to relieve the hypoxic tumor microenvironment in solid tumors. Doxorubicin prodrug (boronate-DOX, BDOX) and β-lapachone were concurrently loaded onto actively targeted pH (low) insertion peptides (pHLIPs)-poly(ethylene glycol) and nitrated gluconic acid copolymers. Our results showed that the ability of P@BDOX/β-lapachone-NO-NPs to generate NO and ROS simultaneously is vital for the sensitization of hypoxic solid tumors for chemotherapy, as evidenced by the suppression of tumor cells and tissues (in vitro and in the nude mice model). Thus, this combined therapy holds considerable potential in the management of hypoxic solid tumors.

Ultrasound Imaging and Antithrombotic Effects of PLA-Combined Fe3O4-GO-ASA Multifunctional Nanobubbles

PLA-combined ferroferric oxide-graphene oxide-aspirin (Fe3O4-GO-ASA) multifunctional nanobubbles were prepared using the double emulsion-solvent evaporation method. The obtained composite nanobubbles had a regular spherical shape, Zeta potential of (-36.5 ± 10.0) mV, and particle size distribution range of 200-700 nm. The experimental results showed that PLA-combined Fe3O4-GO-ASA nanobubbles could effectively improve the antithrombin parameters of PT, TT, APTT, and INR, and significantly inhibit thrombosis when the composite nanobubbles with a concentration of 80 mg·mL-1 interacted with the rabbit blood. The prepared composite nanobubbles could reach a significant ultrasonic imaging effect and good magnetic targeting under the magnetic field when the nanobubbles' concentration was only 60 mg·mL-1.

Combining Mechanical High-Intensity Focused Ultrasound Ablation with Chemotherapy for Augmentation of Anticancer Immune Responses

As a noninvasive therapy, high-intensity focused ultrasound (HIFU) shows great potential in inducing anticancer immune responses. However, the overall anticancer efficacy of HIFU is still limited due to the rapid attenuation of ultrasound waves and inadequacy of ultrasound waves to spread to the whole tumor. Here, we combined HIFU with the ultrasound contrast agent/chemotherapeutic drug co-delivery nanodroplets to achieve synergistic enhancement of anticancer efficacy. Different from the widely used thermal HIFU irradiation, by which excessive heating would result in inactivation of immune stimulatory molecules, we used short acoustic pulses to trigger HIFU (mechanical HIFU, mHIFU) to improve anticancer immune responses. The nanodroplets displayed a mHIFU/glutathione (GSH)-dual responsive drug release property, and their cellular uptake efficacy and toxicity against cancer cells increased upon mHIFU irradiation. The generated immunogenic debris successfully induced the exposure of damage-associated molecular patterns on the cell surface for dendritic cells (DCs) maturation. In vivo experiments with tumor-bearing mice showed that the co-delivery nanodroplets in combination with mHIFU could effectively inhibit tumor growth by inducing immunogenic cell death, activating DCs maturation, and enhancing the effector T-cell infiltration within tumors. This work reveals that combined treatment with nanodroplets and mHIFU is a promising approach to eradicate tumors.

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.

Applications of Micro/Nanotechnology in Ultrasound-based Drug Delivery and Therapy for Tumor

Ultrasound has been broadly used in biomedicine for both tumor diagnosis as well as therapy. The applications of recent developments in micro/nanotechnology promote the development of ultrasound-based biomedicine, especially in the field of ultrasound-based drug delivery and tumor therapy. Ultrasound can activate nano-sized drug delivery systems by different mechanisms for ultrasound- triggered on-demand drug release targeted only at the tumor sites. Ultrasound Targeted Microbubble Destruction (UTMD) technology can not only increase the permeability of vasculature and cell membrane via sonoporation effect but also achieve in situ conversion of microbubbles into nanoparticles to promote cellular uptake and therapeutic efficacy. Furthermore, High Intensity Focused Ultrasound (HIFU), or Sonodynamic Therapy (SDT), is considered to be one of the most promising and representative non-invasive treatment for cancer. However, their application in the treatment process is still limited due to their critical treatment efficiency issues. Fortunately, recently developed micro/nanotechnology offer an opportunity to solve these problems, thus improving the therapeutic effect of cancer. This review summarizes and discusses the recent developments in the design of micro- and nano- materials for ultrasound-based biomedicine applications.

PSMA-targeted melanin-like nanoparticles as a multifunctional nanoplatform for prostate cancer theranostics

Prostate-specific membrane antigen (PSMA) is highly expressed on the surface of most prostate tumor cells and is considered a promising target for prostate cancer imaging and treatment. It is possible to establish a PSMA-targeted theranostic probe to achieve early diagnosis and treatment of this cancer type. In this contribution, we prepared a multifunctional melanin-like polydopamine (PDA) nanocarrier decorated with a small-molecule PSMA inhibitor, N-[N-[(S)-1,3-dicarboxypropyl]carbamoyl]-(S)-l-lysine (DCL). PDA-DCL was then functionalized with perfluoropentane (PFP) and loaded with the photosensitizer chlorin e6 (Ce6) to give Ce6@PDA-DCL-PFP, which was successfully used for ultrasound-guided combined photodynamic/photothermal therapy (PDT/PTT) of prostate cancer. Compared with the corresponding non-targeted probe (Ce6@PDA-PEG-PFP), our targeted probe induced higher cellular uptake in vitro (6.5-fold) and more tumor accumulation in vivo (4.6-fold), suggesting strong active targeting capacity. Meanwhile, this new nanoplatform significantly enhanced the ultrasound contrast signal at the tumor site in vivo, thus facilitating precise and real-time detection of the tumor. In addition, this Ce6-loaded PDA nanoplatform produced a synergistic effect of PDT and PTT under 660 nm and 808 nm irradiation, inducing a more efficient killing effect compared with the individual therapy in vitro and in vivo. Furthermore, the tumor in the targeted group was more effectively suppressed than that in the non-targeted group under the same irradiation condition. This multifunctional probe may hold great potential for precise and early theranostics of prostate cancer.

MRI-traceable theranostic nanoparticles for targeted cancer treatment

Current cancer therapies, including chemotherapy and radiotherapy, are imprecise, non-specific, and are often administered at high dosages - resulting in side effects that severely impact the patient's overall well-being. A variety of multifunctional, cancer-targeted nanotheranostic systems that integrate therapy, imaging, and tumor targeting functionalities in a single platform have been developed to overcome the shortcomings of traditional drugs. Among the imaging modalities used, magnetic resonance imaging (MRI) provides high resolution imaging of structures deep within the body and, in combination with other imaging modalities, provides complementary diagnostic information for more accurate identification of tumor characteristics and precise guidance of anti-cancer therapy. This review article presents a comprehensive assessment of nanotheranostic systems that combine MRI-based imaging (T1 MRI, T2 MRI, and multimodal imaging) with therapy (chemo-, thermal-, gene- and combination therapy), connecting a range of topics including hybrid treatment options (e.g. combined chemo-gene therapy), unique MRI-based imaging (e.g. combined T1-T2 imaging, triple and quadruple multimodal imaging), novel targeting strategies (e.g. dual magnetic-active targeting and nanoparticles carrying multiple ligands), and tumor microenvironment-responsive drug release (e.g. redox and pH-responsive nanomaterials). With a special focus on systems that have been tested in vivo, this review is an essential summary of the most advanced developments in this rapidly evolving field.

Probabilistic modelling of nanobiomaterial release from medical applications into the environment

Nanobiomaterials (NBMs) are currently being tested in numerous biomedical applications, and their use is expected to grow rapidly in the near future. Many different types of nanomaterials are employed for a wide variety of different applications. Silver nanoparticles (nano-Ag) have been investigated for their antibacterial, antifungal, and osteoinductive properties to be used in catheters, wound healing, dental applications, and bone healing. Polymeric nanoparticles such as poly(lactic-co-glycolic acid) (PLGA) are mainly studied for their ability to deliver cancer drugs as the body metabolizes them into simple compounds. However, most of these applications are still in the development stage and unavailable on the market, meaning that information on possible consumption, material flows, and concentrations in the environment is lacking. We thus modeled a realistic scenario involving several nano-Ag and PLGA applications which are already in use or likely to reach the market soon. We assumed their full market penetration in Europe in order to explore the prospective flows of NBMs and their environmental concentrations. The potential flows of three application-specific composite materials were also examined for one precise application each: Fe₃O₄PEG-PLGA used in drug delivery, MgHA-collagen used for bone tissue engineering, and PLLA-Ag applied in wound healing. Mean annual consumption in Europe, considering all realistic and probable applications of the respective NBMs, was estimated to be 5,650 kg of nano-Ag and 48,000 kg of PLGA. Mean annual consumption of the three application-specific materials under the full market penetration scenario was estimated to be 4,000 kg of Fe₃O₄PEG-PLGA, 58 kg of MgHA-collagen, and 24,300 kg of PLLA-Ag. A probabilistic material-flow model was used to quantify flows of the NBMs studied from production, through use, and on to end-of-life in the environment. The highest possible worst-case predicted environmental concentration (wc-PEC) were found to occur in sewage sludge, with 0.2 µg/kg of nano-Ag, 400 µg/kg of PLGA, 33 µg/kg of Fe₃O₄PEG-PLGA, 0.007 µg/kg of MgHA-collagen, and 2.9 µg/kg of PLLA-Ag. PLGA exhibited the highest concentration in all environmental compartments except natural and urban soil, where nano-Ag showed the highest concentration. The results showed that the distribution of NBMs into different environmental and technical compartments is strongly dependent on their type of application.

Tumor Targeted Multifunctional Magnetic Nanobubbles for MR/US Dual Imaging and Focused Ultrasound Triggered Drug Delivery

The development of multifunctional nanoplatforms that are safe and have multiple therapeutic functions integrated with dual- or multi-imaging modality is one of the most urgent medical requirements for active cancer therapy. In our study, we prepared multifunctional magnetic nanobubbles (MF-MNBs) by co-encapsulating superparamagnetic iron oxide nanoparticles (SPIONs) and doxorubicin into polylactideco–glycolide–polyethylene glycol–folate (PLGA-PEG-FA) polymer-based nanobubbles for tumor-targeted ultrasound (US)/magnetic resonance (MR) imaging and focused ultrasound (FUS)-triggered drug delivery. Hydrophobic SPIONs were successfully embedded into MF-MNBs by a typical double emulsion process. The MF-MNBs were highly dispersed with well-defined spherical morphology and an average diameter of 208.4 ± 12.58 nm. The potential of MF-MNB as a dual-modal contrast agent for US and MR imaging was investigated via in vitro study, and the MF-MNB exhibits promising US/MR contrast ability. Moreover, tumor targeting ability was further enhanced by folate conjugation and assessed through in vitro cell test. Furthermore, FUS, as a non-invasive and remote-control technique, was adopted to trigger the release of doxorubicin from MF-MNB and generate the sonoporation effect to enhance drug release and cellular uptake of MF-MNBs. The 4T1 cell viability was significantly decreased by FA ligand-receptor-mediated targeting and FUS sonication. In addition, the developed MF-MNB also exhibits enhanced accumulation in tumor site by FA ligand-receptor-mediated tumor targeting, in which the accumulation of MF-MNB was further enhanced by FUS sonication. Hence, we believe that the MF-MNB could be a promising drug nanocarrier for US/MR-guided anticancer drug delivery to improve cancer treatment efficacy.

Effects of buoyant and Saffman lift force on magnetic drug targeting in microvessel in the presence of inertia

The conventional techniques in treating cancerous cells in a human body are conducted either by surgery or oral medication or injecting anticancer drugs, which may have several side effects on healthy cells. Compared to these techniques, site-specific delivery of drugs can be one of the pillars of cancer treatment. It could allow for better treatment efficiency and lesser adverse effects. A promising drug delivery approach is magnetic drug targeting, which can be realized if a drug delivery vehicle possesses an intense magnetic moment. Here, we discuss different types of magnetic nanomaterials, which can be used as magnetic drug delivery vehicles, approaches to magnetically targeted delivery, and promising strategies for the enhancement of the imaging-guided delivery and the therapeutic action. The present study aims to discuss all significant factors that influence the process of magnetic drug targeting through microvessels, such as fluidic force, magnetic force, particle-particle interaction, inertia force, Saffman lift force, and permeability of the microvessel. We consider the nature of blood flow as non-Newtonian in single-phase and two-phase models so that a realistic rheological model for an effective magnetic drug targeting can be established through proper comparison. Here we present a comprehensive mathematical model on magnetic drug targeting that could help the medical experts and biomedical engineers in applying the methodology of magnetic drug targeting effectively to cure cancerous disease.

Magnetic resonance imaging of high-intensity focused ultrasound-stimulated drug release from a self-reporting core@shell nanoparticle platform

We developed a theranostic approach exemplifying a concept called an "exchange method" that controls and "images" drug release from nanoparticles using magnetic resonance imaging-guided high-intensity focused ultrasound. The controllable amount of released drug and therapeutic efficacy can be self-reported by associated MRI contrast changes in solution and in cells.