Insights into the unique functionality of inorganic micro/nanoparticles for versatile ultrasound theranostics

A Distinctive Insight into Inorganic Sonosensitizers: Design Principles and Application Domains

Sonodynamic therapy (SDT) as a promising non-invasive anti-tumor means features the preferable penetration depth, which nevertheless, usually can't work without sonosensitizers. Sonosensitizers produce reactive oxygen species (ROS) in the presence of ultrasound to directly kill tumor cells, and concurrently activate anti-tumor immunity especially after integration with tumor microenvironment (TME)-engineered nanobiotechnologies and combined therapy. Current sonosensitizers are classified into organic and inorganic ones, and current most reviews only cover organic sonosensitizers and highlighted their anti-tumor applications. However, there have few specific reviews that focus on inorganic sonosensitizers including their design principles, microenvironment regulation, etc. In this review, inorganic sonosensitizers are first classified according to their design rationales rather than composition, and the action rationales and underlying chemistry features are highlighted. Afterward, what and how TME is regulated based on the inorganic sonosensitizers-based SDT nanoplatform with an emphasis on the TME targets-engineered nanobiotechnologies are elucidated. Additionally, the combined therapy and their applications in non-cancer diseases are also outlined. Finally, the setbacks and challenges, and proposed the potential solutions and future directions is pointed out. This review provides a comprehensive and detailed horizon on inorganic sonosensitizers, and will arouse more attentions on SDT.

Self-Monitoring Theranostic Nanomaterials: Emerging Visual Agents for Real-Time Monitoring of Tumor Treatment Processes

Self-monitoring in tumor therapy is a concept that allows for real-time monitoring of the location and state of applied nanomaterials. This monitoring relies on dynamic signals, such as wave or magnetic signals, which vary in response to changes in the location and state of nanomaterials. Dynamic changes in nanomaterials can be monitored using dynamic signals, making it possible to determine and control the treatment process. Theranostic nanomaterials, which possess unique physical and chemical properties, have recently been explored as a viable option for self-monitoring. With the help of self-monitoring, theranostic nanomaterials can guide themselves to achieve region-selective treatment with higher controllability and safety. In this review, self-monitoring theranostic nanomaterials will be introduced in three parts according to their roles during therapy: tumor accumulation, tumor therapy, and metabolism. The limitations and future challenges of current self-monitoring theranostic nanomaterials will also be discussed.

Nanomedicine/materdicine-enabled sonocatalytic therapy

The advent of numerous treatment modalities with desirable therapeutic efficacy has been made possible by the fast development of nanomedicine and materdicine, among which the ultrasound (US)-triggered sonocatalytic process as minimal or non-invasive method has been frequently employed for diagnostic and therapeutic purposes. In comparison to phototherapeutic approaches with inherent penetration depth limitations, sonocatalytic therapy shatters the depth limit of photoactivation and offers numerous remarkable prospects and advantages, including mitigated side effects and appropriate tissue-penetration depth. Nevertheless, the optimization of sonosensitizers and therapies remains a significant issue in terms of precision, intelligence and efficiency. In light of the fact that nanomedicine and materdicine can effectively enhance the theranostic efficiency, we herein aim to furnish a cutting-edge review on the latest progress and development of nanomedicine/materdicine-enabled sonocatalytic therapy. The design methodologies and biological features of nanomedicine/materdicine-based sonosensitizers are initially introduced to reveal the underlying relationship between composition/structure, sonocatalytic function and biological effect, in accompany with a thorough discussion of nanomedicine/materdicine-enabled synergistic therapy. Ultimately, the facing challenges and future perspectives of this intriguing sonocatalytic therapy are highlighted and outlined to promote technological advancements and clinical translation in efficient disease treatment.

5-aminolevulinic acid sonodynamic therapy for cutaneous squamous cell carcinoma

BACKGROUND

The treatment of deep-invasive cutaneous squamous cell carcinoma (cSCC) is difficult. Sonodynamic therapy (SDT) has showed advantages in large penetration depth, small trauma, good repeatability, high targeting selectivity and effective protection for intact structure and function of tissues and organs.

OBJECTIVE

To study the efficacy and safety of 5-aminolevulinic acid SDT (ALA-SDT) in the treatment of cSCC.

METHODS

The absorption and transformation of ALA after co-incubation with cSCC were detected by UV-Vis and fluorescence absorption. The production of reactive oxygen species (ROS) when protoporphyrin IX (PpIX) excited with ultrasound was detected by ROS detection probe. Cytotoxicity of ALA-SDT to cSCC was detected with cytotoxicity indicators. The tumor volume changes and tumor weight of mice after ALA-SDT were detected. The effects of ALA-SDT on the growth of mice were evaluated through the changes in body weight of mice. Biosafety of treatment was further evaluated by histopathology to determine whether the tissues and organs of mice were affected after ALA-SDT.

RESULTS

ALA can be absorbed and converted into PpIX when incubated with cSCC cells and produces ROS with ultrasound irradiation. ALA-SDT showed a significant cytotoxicity on cSCC cells. With one session of ALA-SDT in vivo, tumor growth was slowed but not stopped and would proceed once treatment was ended. ALA-SDT had no significant effect on body weight changes and major tissues and organs of the mice.

CONCLUSION

ALA-SDT could safely and reduce cSCC cells growth both in vitro and in vivo.

Logic gate controlled theranostic nanoagents for in situ microwave thermal therapeutic efficacy evaluation

In vivo monitoring of treatment response is of great significance for tumor therapy in clinical trials, but it remains a formidable challenge. Herein, we demonstrate a logic AND gate theranostic nanoagent that responds to the coexistence of endogenous and exogenous stimuli, namely HAuCl4@1-Tetradecanol@Gd-based metal-organic framework@SiO2 nanocomposites (APGS NCs). Upon microwave (MW) irradiation, HAuCl4 in the inner part of APGS NCs reacts with the tumor-associated glutathione (GSH). Subsequently, it transforms into an active luminescent form of Au@1-Tetradecanol@Gd-MOF@SiO2 nanocomposites (AuPGS NCs). The intensity of generated fluorescence is correlated with the tumor thermal-injury status. Thus, the generation of AuPGS NCs with high intensity fluorescence under the co-activation of MW and GSH can visualize the treatment effects during MW thermal therapy and instantly modulate the irradiation time and range for optimal outcomes. Hence, this logic gate controlled APGS NCs makes MW thermal therapy eliminate tumor cells completely. This research offers an effective strategy for the design and preparation of activatable theranostic nanoagents for precise tumor imaging and therapy.

Recent Developments of Inorganic Nanosensitizers for Sonodynamic Therapy

As a noninvasive treatment, sonodynamic therapy (SDT) has been widely used in the treatment of tumors because of its ability to penetrate deep tissue with few side effects. As the key factor of SDT, it is meaningful to design and synthesize efficient sonosensitizers. Compared with organic sonosensitizers, inorganic sonosensitizers can be easily excited by ultrasound. In addition, inorganic sonosensitizers with stable properties, good dispersion, and long blood circulation time, have great development potential in SDT. This review summarizes possible mechanisms of SDT (sonoexcitation and ultrasonic cavitation) in detail. Based on these mechanisms, the design and synthesis of inorganic nanosonosensitizers can be divided into three categories: traditional inorganic semiconductor sonosensitizers, enhanced inorganic semiconductor sonosensitizers, and cavitation-enhanced sonosensitizers. Subsequently, the current efficient construction methods of sonosensitizers are summarized including accelerated semiconductor charge separation and enhanced production of reactive oxygen species through ultrasonic cavitation. Furthermore, the advantages and disadvantages of different inorganic sonosensitizers and detailed strategies are systematically discussed on how to enhance SDT. Hopefully, this review could provide new insights into the design and synthesis of efficient inorganic nano-sonosensitizers for SDT.

Polymeric Phthalocyanine-Based Nanosensitizers for Enhanced Photodynamic and Sonodynamic Therapies

Photodynamic therapy and sonodynamic therapy are two highly promising modalities for cancer treatment. The latter holds an additional advantage in deep-tumor therapy owing to the deep penetration of the ultrasonic radiation. The therapeutic efficacy depends highly on the photo/ultrasound-responsive properties of the sensitizers as well as their tumor-localization property and pharmacokinetics. A novel nanosensitizer system based on a polymeric phthalocyanine (pPC-TK) is reported herein in which the phthalocyanine units are connected with cleavable thioketal linkers. Such polymer could self-assemble in water forming nanoparticles with a hydrodynamic diameter of 48 nm. The degradable and flexible thioketal linkers could effectively inhibit the π-π stacking of the phthalocyanine units, rendering the resulting nanoparticles an efficient generator of reactive oxygen species upon light or ultrasonic irradiation. The nanosensitizer could be internalized into cancer cells readily, inducing cell death by efficient photodynamic and sonodynamic effects. The potency is significantly higher than that of the monomeric phthalocyanine (PC-4COOH). The nanosensitizer could also effectively inhibit the growth of tumor in liver tumor-bearing mice by these two therapies without causing noticeable side effects. More importantly, it could also retard the growth of a deep-located orthotopic liver tumor in vivo by sonodynamic therapy.

Ultrasonic interfacial crosslinking of TiO2-based nanocomposite hydrogels through thiol-norbornene reactions for sonodynamic antibacterial treatment

Nanocomposite (NC) hydrogels used for sonodynamic therapy (SDT) face challenges such as lacking interfacial interactions between the polymers and nanomaterials as well as presenting uneven dispersion of nanomaterials in the hydrogel network, reducing their mechanical properties and treatment efficiency. Here, we demonstrate a promising approach of co-engineering nanomaterials and interfacial crosslinking to expand the materials construction and biomedical applications of NC hydrogels in SDT. In this work, mesoporous silica-coated titanium dioxide nanoparticles with thiolated surface functionalization (TiO₂@MS-SH) are utilized as crosslinkers to react with norbornene-functionalized dextran (Nor-Dex) through ultrasound-triggered thiol-norbornene reactions, forming TiO₂@MS-SH/Nor-Dex NC hydrogels. The TiO₂@MS-SH nanoparticles act not only as multivalent crosslinkers to improve the mechanical properties of hydrogels under ultrasound irradiation but also as reactive oxygen species (ROS) generators to allow the use of TiO₂@MS-SH/Nor-Dex NC hydrogels in SDT applications. Particularly, the TiO₂@MS-SH/Nor-Dex NC hydrogels present tailorable microstructures, properties, and sonodynamic killing of bacteria through the modulation of the ultrasound frequency. Taken together, a versatile TiO₂-based NC hydrogel platform prepared under ultrasonic interfacial crosslinking reactions is developed for advancing the applications in SDT.

Smart Nanomaterials in Cancer Theranostics: Challenges and Opportunities

Cancer is ranked as the second leading cause of death globally. Traditional cancer therapies including chemotherapy are flawed, with off-target and on-target toxicities on the normal cells, requiring newer strategies to improve cell selective targeting. The application of nanomaterial has been extensively studied and explored as chemical biology tools in cancer theranostics. It shows greater applications toward stability, biocompatibility, and increased cell permeability, resulting in precise targeting, and mitigating the shortcomings of traditional cancer therapies. The nanoplatform offers an exciting opportunity to gain targeting strategies and multifunctionality. The advent of nanotechnology, in particular the development of smart nanomaterials, has transformed cancer diagnosis and treatment. The large surface area of nanoparticles is enough to encapsulate many molecules and the ability to functionalize with various biosubstrates such as DNA, RNA, aptamers, and antibodies, which helps in theranostic action. Comparatively, biologically derived nanomaterials perceive advantages over the nanomaterials produced by conventional methods in terms of economy, ease of production, and reduced toxicity. The present review summarizes various techniques in cancer theranostics and emphasizes the applications of smart nanomaterials (such as organic nanoparticles (NPs), inorganic NPs, and carbon-based NPs). We also critically discussed the advantages and challenges impeding their translation in cancer treatment and diagnostic applications. This review concludes that the use of smart nanomaterials could significantly improve cancer theranostics and will facilitate new dimensions for tumor detection and therapy.

In Situ Coatings of Polymeric Films with Core Polystyrene, Core-Shell Polystyrene/SiO2, and Hollow SiO2 Micro/Nanoparticles and Potential Applications

In many industrial settings, films of polymers such as polypropylene (PP) and polyethylene terephthalate (PET) require surface treatment due to poor wettability and low surface energy. Here, a simple process is presented to prepare durable thin coatings composed of polystyrene (PS) core, PS/SiO₂ core-shell, and hollow SiO₂ micro/nanoparticles onto PP and PET films as a platform for various potential applications. Corona-treated films were coated with a monolayer of PS microparticles by in situ dispersion polymerization of styrene in ethanol/2-methoxy ethanol with polyvinylpyrrolidone as stabilizer. A similar process on untreated polymeric films did not yield a coating. PS/SiO₂ core-shell coated microparticles were produced by in situ polymerization of Si(OEt)₄ in ethanol/water onto a PS-coated film, creating a raspberry-like morphology with a hierarchical structure. Hollow porous SiO₂-coated microparticles onto a PP/PET film were formed by in situ dissolution of the PS core of the coated PS/SiO₂ particles with acetone. The coated films were characterized by E-SEM, FTIR/ATR, and AFM. These coatings may be used as a platform for various applications, e.g. magnetic coatings onto the core PS, superhydrophobic coatings onto the core-shell PS/SiO₂, and solidification of oil liquids within the hollow porous SiO₂ coating.

Ultrasound nanomedicine and materdicine

The conventional microbubble-based ultrasound biomedicine clinically plays a vital role in providing the dynamic detection of macro and microvasculature and disease theranostics. However, the intrinsic limitation of particle size severely decreases the treatment effectiveness due to their vascular transport characteristics, which promotes the development and application of multifunctional ultrasound-responsive nanomaterials. Herein, we put forward a research field of "ultrasound nanomedicine and materdicine", referring to the interdiscipline of ultrasound, nanobiotechnology and materials, which seeks to produce specific biological effects for addressing the challenges faced and dilemma of conventional ultrasound medicine. We comprehensively summarize the state-of-the-art scientific advances in the latest progress in constructing ultrasound-based platforms and ultrasound-activated sonosensitizers, ranging from the synthesis strategies, biological functions to ultrasound-triggered therapeutic applications. Ultimately, the unresolved challenges and clinical-translation potentials of ultrasound nanomedicine and materdicine are discussed and prospected in this evolving field.

Cooperative Functionalities in Porous Nanoparticles for Seeking Extracellular DNA and Targeting Pathogenic Biofilms via Photodynamic Therapy

Many pathogenic bacteria are getting more and more resistant against antibiotic treatment and even become up to 1.000× times more resilient in the form of a mature biofilm. Thus, one is currently prospecting for alternative methods for treating microbial infections, and photodynamic therapy is a highly promising approach by creating so-called reactive oxygen species (ROS) produced by a photosensitizer (PS) upon irradiation with light. Unfortunately, the unspecific activity of ROS is also problematic as they are harmful to healthy tissue as well. Notably, one knows that uncontrolled existence of ROS in the body plays a major role in the development of cancer. These arguments create need for advanced theranostic materials which are capable of autonomous targeting and detecting the existence of a biofilm, followed by specific activation to combat the infection. The focus of this contribution is on mesoporous organosilica colloids functionalized by orthogonal and localized click-chemistry methods. The external zone of the particles is modified by a dye of the Hoechst family. The particles readily enter a mature biofilm where adduct formation with extracellular DNA and a resulting change in the fluorescence signal occurs, but they cannot cross cellular membranes such as in healthy tissue. A different dye suitable for photochemical ROS generation, Acridine Orange, is covalently linked to the surfaces of the internal mesopores. The spectral overlap between the emission of Hoechst with the absorption band of Acridine Orange facilitates energy transfer by Förster resonance with up to 88% efficiency. The theranostic properties of the materials including viability studies were investigated in vitro on mature biofilms formed by Pseudomonas fluorescens and prove the high efficacy.

Nanotechnology meets glioblastoma multiforme: Emerging therapeutic strategies

Glioblastoma multiforme (GBM) represents the most common and fatal form of primary invasive brain tumors as it affects a great number of patients each year and has a median overall survival of approximately 14.6 months after diagnosis. Despite intensive treatment, almost all patients with GBM experience recurrence, and their 5-year survival rate is approximately 5%. At present, the main clinical treatment strategy includes surgical resection, radiotherapy, and chemotherapy. However, tumor heterogeneity, blood-brain barrier, glioma stem cells, and DNA damage repair mechanisms hinder efficient GBM treatment. The emergence of nanometer-scale diagnostic and therapeutic approaches in cancer medicine due to the establishment of nanotechnology provides novel and promising tools that will allow us to overcome these difficulties. This review summarizes the application and recent progress in nanotechnology-based monotherapies (e.g., chemotherapy) and combination cancer treatment strategies (chemotherapy-based combined cancer therapy) for GBM and describes the synergistic enhancement between these combination therapies as well as the current standard therapy for brain cancer and its deficiencies. These combination therapies that can reduce individual drug-related toxicities and significantly enhance therapeutic efficiency have recently undergone rapid development. The mechanisms underlying these different nanotechnology-based therapies as well as the application of nanotechnology in GBM (e.g., in photodynamic therapy and chemodynamic therapy) have been systematically summarized here in an attempt to review recent developments and to identify promising directions for future research. This review provides novel and clinically significant insights and directions for the treatment of GBM, which is of great clinical importance. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Diagnostic Tools > In Vivo Nanodiagnostics and Imaging.

Degradable Multifunctional Porphyrin-Based Porous Organic Polymer Nanosonosensitizer for Tumor-Specific Sonodynamic, Chemo- and Immunotherapy

Sonodynamic therapy (SDT) benefiting from its intrinsic merits, such as noninvasiveness and deep tissue penetrability, is receiving increasing considerable attention in reactive oxygen species (ROS)-based tumor treatment. However, current sonosensitizers usually suffer from low tumor lesion accumulation, insufficient ROS generation efficiency under ultrasound, and non-biodegradability, which seriously impede the therapeutic outcomes. Additionally, it is difficult that SDT alone can completely eradicate tumors because of the complex and immunosuppressive tumor microenvironment (TME). Herein, we simultaneously employ sonosensitive porphyrin building blocks and glutathione (GSH)-responsive disulfide bonds to construct a novel degradable multifunctional porphyrin-based hollow porous organic polymer (POP) nanosonosensitizer (H-Pys-HA@M/R), which combine SDT, "on-demand" chemotherapy, and immunotherapy. Taking the unique advantages of POPs with designable structures and high specific surface area, this H-Pys-HA@M/R nanosonosensitizer can achieve tumor target accumulation, GSH-triggered drug release, and low-frequency ultrasound-activating ROS generation with encouraging results. Furthermore, this multifunctional nanosonosensitizer can effectively evoke immunogenic cell death (ICD) response through the combination of SDT and chemotherapy for both primary and distal tumor growth suppression. Meanwhile, H-Pys-HA@M/R exhibits favorable biodegradation and biosafety. Therefore, this study provides a new strategy for reasonably designing and constructing POP-related sonosensitizers combining SDT/chemotherapy/immunotherapy triple treatment modalities to eradicate malignant tumors.

The promising interplay between sonodynamic therapy and nanomedicine

Sonodynamic therapy (SDT) is a non-invasive approach for cancer treatment in which chemical compounds, named sonosensitizers, are activated by non-thermal ultrasound (US), able to deeply penetrate into the tissues. Despite increasing interest, the underlying mechanisms by which US triggers the sonosensitizer therapeutic activity are not yet clearly elucidate, slowing down SDT clinical application. In this review we will discuss the main mechanisms involved in SDT with particular attention to the sonosensitizers involved for each described mechanism, in order to highlight how much important are the physicochemical properties of the sonosensitizers and their cellular localization to predict their bioeffects. Moreover, we will also focus our attention on the pivotal role of nanomedicine providing the sonodynamic anticancer approach with the ability to shape US-responsive agents to enhance specific sonodynamic effects as the sonoluminescence-mediated anticancer effects. Indeed, SDT is one of the biomedical fields that has significantly improved in recent years due to the increased knowledge of nanosized materials. The shift of the nanosystem from a delivery system for a therapeutic agent to a therapeutic agent in itself represents a real breakthrough in the development of SDT. In doing so, we have also highlighted potential areas in this field, where substantial improvements may provide a valid SDT implementation as a cancer therapy.

Dual-Mode Fluorescence/Ultrasound Imaging with Biocompatible Metal-Doped Graphene Quantum Dots

Sonography offers many advantages over standard methods of diagnostic imaging due to its non-invasiveness, substantial tissue penetration depth, and low cost. The benefits of ultrasound imaging call for the development of ultrasound-trackable drug delivery vehicles that can address a variety of therapeutic targets. One disadvantage of the technique is the lack of high-precision imaging, which can be circumvented by complementing ultrasound contrast agents with visible and, especially, near-infrared (NIR) fluorophores. In this work, we, for the first time, develop a variety of lightly metal-doped (iron oxide, silver, thulium, neodymium, cerium oxide, cerium chloride, and molybdenum disulfide) nitrogen-containing graphene quantum dots (NGQDs) that demonstrate high-contrast properties in the ultrasound brightness mode and exhibit visible and/or near-infrared fluorescence imaging capabilities. NGQDs synthesized from glucosamine precursors with only a few percent metal doping do not introduce additional toxicity in vitro, yielding over 80% cell viability up to 2 mg/mL doses. Their small (<50 nm) sizes warrant effective cell internalization, while oxygen-containing surface functional groups decorating their surfaces render NGQDs water soluble and allow for the attachment of therapeutics and targeting agents. Utilizing visible and/or NIR fluorescence, we demonstrate that metal-doped NGQDs experience maximum accumulation within the HEK-293 cells 6-12 h after treatment. The successful 10-fold ultrasound signal enhancement is observed at 0.5-1.6 mg/mL for most metal-doped NGQDs in the vascular phantom, agarose gel, and animal tissue. A combination of non-invasive ultrasound imaging with capabilities of high-precision fluorescence tracking makes these metal-doped NGQDs a viable agent for a variety of theragnostic applications.

Defect Engineering Triggers Exceptional Sonodynamic Activity of Manganese Oxide Nanoparticles for Cancer Therapy

Sonodynamic therapy (SDT) has received increasing interest in cancer treatment, but its clinical application is still constrained by the low activity of sonosensitizers and their unclear mechanism. Herein, a kind of oxygen-deficient manganese oxide (MnOx) nanoparticles with greatly enhanced sonodynamic activity and good biocompatibility is developed as an advanced sonosensitizer. The introduced oxygen defects can remarkably enhance the electrical conductivity of manganese oxide (MnO) nanoparticles and serve as charge trapping sites to prohibit the electron-hole pair recombination upon ultrasound (US) irradiation. Such distinct merits promote the generation of reactive oxygen species (ROS), making MnOx as a decent sonosensitizer for SDT, and thus endowing MnOx with higher ROS production under US irradiation. As a demonstration, the MnOx nanoparticles decorated by 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (MnOx-DSPE-PEG), a biocompatible coverage to enhance the dispersion ability, achieve a superior tumor killing efficiency of 96%, substantially higher than the MnO-DSPE-PEG counterpart (9%). Our experimental results also reveal that MnOx-DSPE-PEG nanoparticles induce the death of tumor cells by targeting polyunsaturated fatty acids in their membrane with US-triggered ROS. Furthermore, the as-designed sonosensitizers exhibit negligible toxicity toward the treated mice.

A MXene-derived redox homeostasis regulator perturbs the Nrf2 antioxidant program for reinforced sonodynamic therapy

Ultrasound (US)-mediated sonodynamic therapy (SDT) has emerged as a spatiotemporally controllable therapeutic modality in combating cancer because of its high tissue-penetration depth and minimal invasiveness. However, the elevated nuclear factor erythroid 2-related factor 2 (Nrf2) antioxidant program in cancer cells can serve as a chief reactive oxygen species (ROS) detoxification system to alleviate oxidative injury and promote tumorigenesis, and thus greatly antagonize the therapeutic efficacy of ROS-mediated anticancer therapies. Herein, we report that vanadium carbide MXene-derived carbon dots (PMQDs) can act as high-efficacy sonosensitizers to efficiently generate ROS upon US irradiation and simultaneously hinder the Nrf2 antioxidant program for enhanced sonodynamic therapy of cancer. These PMQDs show superior US-triggered ROS generating ability because of their efficient migration/separation of electron-hole pairs and narrow bandgap. Importantly, these PMQDs can serve as efficient redox homeostasis regulators to perturb the Nrf2 antioxidant mechanism and thus reduce its effects on ROS neutralization for enhanced SDT efficacy. Overall, the present study will not only provide a new paradigm to augment SDT by perturbing the Nrf2 antioxidant program, but also give valuable insights into developing high-efficacy MXene-derived nanoagents for cancer therapy.

Recent Advances in Transition-Metal Based Nanomaterials for Noninvasive Oncology Thermal Ablation and Imaging Diagnosis

With the developments of nanobiotechnology and nanomedicine, non-invasive thermal ablation with fewer side effects than traditional tumor treatment methods has received extensive attention in tumor treatment. Non-invasive thermal ablation has the advantages of non-invasiveness and fewer side effects compared with traditional treatment methods. However, the clinical efficiency and biological safety are low, which limits their clinical application. Transition-metal based nanomaterials as contrast agents have aroused increasing interest due to its unique optical properties, low toxicity, and high potentials in tumor diagnosis. Transition-metal based nanomaterials have high conversion efficiency of converting light energy into heat energy, good near-infrared absorption characteristics, which also can targetedly deliver those loaded drugs to tumor tissue, thereby improving the therapeutic effect and reducing the damage to the surrounding normal tissues and organs. This article mainly reviews the synthesis of transition-metal based nanomaterials in recent years, and discussed their applications in tumor thermal ablation and diagnosis, hopefully guiding the development of new transition metal-based nanomaterials in enhancing thermal ablation.

Dual-imaging magnetic nanocatalysis based on Fenton-like reaction for tumor therapy

Sequential nano-catalytic therapy has emerged as a novel therapeutic modality for cancer treatment as it utilizes the unique tumor microenvironment for selective tumor treatment. This study reports a magnetic nanoparticle to achieve Fenton-like reaction and dual-imaging guidance/monitoring. Natural glucose oxidase (GOx) and superparamagnetic Fe₃O₄ nanoparticles have been integrated into poly(lactic-co-glycolic acid) (PLGA) to fabricate a sequential nanocatalyst (designated as GOx@PLGA-Fe₃O₄). This nanocatalyst can functionally deplete glucose in tumor tissues, producing a considerable amount of highly cytotoxic hydroxyl radicals via the sequential Fenton-like reaction, and meanwhile maximizing the potential imaging capability as a contrast agent for magnetic resonance imaging and photoacoustic imaging. By ribonucleic acid sequencing (RNA-seq) technology, GOx@PLGA-Fe₃O₄ nanoparticles are demonstrated to induce tumor cell death by inhibiting multiple gene regulation pathways involving tumor growth and recurrence. Therefore, this finding provides a novel strategy to achieve promising therapeutic efficacy by the rational design of multifunctional nanoparticles with various features, including magnetic targeting, sequential nano-catalytic therapy, and dual-imaging guidance/monitoring.

Mechanistic Insights and Therapeutic Delivery through Micro/Nanobubble-Assisted Ultrasound

Ultrasound with low frequency (20–100 kHz) assisted drug delivery has been widely investigated as a non-invasive method to enhance the permeability and retention effect of drugs. The functional micro/nanobubble loaded with drugs could provide an unprecedented opportunity for targeted delivery. Then, ultrasound with higher intensity would locally burst bubbles and release agents, thus avoiding side effects associated with systemic administration. Furthermore, ultrasound-mediated destruction of micro/nanobubbles can effectively increase the permeability of vascular membranes and cell membranes, thereby not only increasing the distribution concentration of drugs in the interstitial space of target tissues but also promoting the penetration of drugs through cell membranes into the cytoplasm. These advancements have transformed ultrasound from a purely diagnostic utility into a promising theragnostic tool. In this review, we first discuss the structure and generation of micro/nanobubbles. Second, ultrasound parameters and mechanisms of therapeutic delivery are discussed. Third, potential biomedical applications of micro/nanobubble-assisted ultrasound are summarized. Finally, we discuss the challenges and future directions of ultrasound combined with micro/nanobubbles.

Stimuli-Responsive Nanoparticles for Controlled Drug Delivery in Synergistic Cancer Immunotherapy

Cancer immunotherapy has achieved promising clinical progress over the recent years for its potential to treat metastatic tumors and inhibit their recurrences effectively. However, low patient response rates and dose-limiting toxicity remain as major dilemmas for immunotherapy. Stimuli-responsive nanoparticles (srNPs) combined with immunotherapy offer the possibility to amplify anti-tumor immune responses, where the weak acidity, high concentration of glutathione, overexpressions of enzymes, and reactive oxygen species, and external stimuli in tumors act as triggers for controlled drug release. This review highlights the design of srNPs based on tumor microenvironment and/or external stimuli to combine with different anti-tumor drugs, especially the immunoregulatory agents, which eventually realize synergistic immunotherapy of malignant primary or metastatic tumors and acquire a long-term immune memory to prevent tumor recurrence. The authors hope that this review can provide theoretical guidance for the construction and clinical transformation of smart srNPs for controlled drug delivery in synergistic cancer immunotherapy.

Tumor-targeting biomimetic sonosensitizer-conjugated iron oxide nanocatalysts for combinational chemodynamic-sonodynamic therapy of colorectal cancer

Nanoparticle-based tumor therapy strategies have been widely developed, while the therapeutic efficacy is often limited due to poor accumulation of nanoparticles in tumor tissues and low antitumor effect of sole...

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-controlled drug release and drug activation for cancer therapy

Traditional chemotherapy suffers from severe toxicity and side effects that limit its maximum application in cancer therapy. To overcome this challenge, an ideal treatment strategy would be to selectively control the release or regulate the activity of drugs to minimize the undesirable toxicity. Recently, ultrasound (US)-responsive drug delivery systems (DDSs) have attracted significant attention due to the non-invasiveness, high tissue penetration depth, and spatiotemporal controllability of US. Moreover, the US-induced mechanical force has been proven to be a robust method to site-selectively rearrange or cleave bonds in mechanochemistry. This review describes the US-activated DDSs from the fundamental basics and aims to present a comprehensive summary of the current understanding of US-responsive DDSs for controlled drug release and drug activation. First, we summarize the typical mechanisms for US-responsive drug release and drug activation. Second, the main factors affecting the ultrasonic responsiveness of drug carriers are outlined. Furthermore, representative examples of US-controlled drug release and drug activation are discussed, emphasizing their novelty and design principles. Finally, the challenges and an outlook on this promising therapeutic strategy are discussed.

Acoustics at the nanoscale (nanoacoustics): A comprehensive literature review.: Part II: Nanoacoustics for biomedical imaging and therapy

In the past decade, acoustics at the nanoscale (i.e., nanoacoustics) has evolved rapidly with continuous and substantial expansion of capabilities and refinement of techniques. Motivated by research innovations in the last decade, for the first time, recent advancements of acoustics-associated nanomaterials/nanostructures and nanodevices for different applications are outlined in this comprehensive review, which is written in two parts. As part II of this two-part review, this paper concentrates on nanoacoustics in biomedical imaging and therapy applications, including molecular ultrasound imaging, photoacoustic imaging, ultrasound-mediated drug delivery and therapy, and photoacoustic drug delivery and therapy. Firstly, the recent developments of nanosized ultrasound and photoacoustic contrast agents as well as their various imaging applications are examined. Secondly, different types of nanomaterials/nanostructures as nanocarriers for ultrasound and photoacoustic therapies are discussed. Finally, a discussion of challenges and future research directions are provided for nanoacoustics in medical imaging and therapy.

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.

Degradable FeCuS-Lipid Nanoparticles Confer Ultrasound-Activated CO Release and O2-Independent Radical Production for Synergistic Therapy

Ultrasound (US)-activated nanoagents capable of producing cytotoxic species have been promising for the treatment of deep-seated tumors; however, poor tumor uptake and insufficient generation of cytotoxic agents have largely limited their therapeutic efficacy in vivo. Herein, we report a hybrid FeCuS-lipid nanoparticle (AIBA@FeCuS-FeCO) by amphiphilic lipids-assisted emulsion of a free radical initiator (AIBA), a radical-sensitive CO donor (Fe₃(CO)₁₂), and radical-degradable FeCuS nanodisks for US-activated synergistic therapy of deep-located orthotopic gastric tumors in living mice. Upon US irradiation, AIBA@FeCuS-FeCO could be degraded and release cytotoxic AIBA radicals, CO, Fe²⁺, and Cu²⁺, allowing us to (1) enhance tumor uptake of AIBA@FeCuS-FeCO through CO-mediated vasodilation, (2) promote hydroxyl radical production and induce tumor ferroptosis via intracellular accumulation of Fe²⁺/Cu²⁺, and (3) kill tumor cells. Moreover, the subsequent administration of disulfiram (DSF) could further chelate with the liberated Cu²⁺, yielding toxic bis(N,N-diethyl dithiocarbamato)copper(II) chelates to synergize the therapeutic effect to ablate deep-seated orthotopic gastric tumors.

Multiple-therapy strategies via polysaccharides-based nano-systems in fighting cancer

Polysaccharide-based biomaterials (e.g., chitosan, dextran, hyaluronic acid, chondroitin sulfate and heparin) have received great attention in healthcare, particularly in drug delivery for tumor therapy. They are naturally abundant and available, outstandingly biodegradable and biocompatible, and they generally have negligible toxicity and low immunogenicity. In addition, they are easily chemically or physically modified. Therefore, PSs-based nanoparticles (NPs) have been extensively investigated for the enhancement of tumor treatment. In this review, we introduce the synthetic pathways of amphiphilic PS derivatives, which allow the constructs to self-assemble into NPs with various structures. We especially offer an overview of the emerging applications of self-assembled PSs-based NPs in tumor chemotherapy, photothermal therapy (PTT), photodynamic therapy (PDT), gene therapy and immunotherapy. We believe that this review can provide criteria for a rational and molecular level-based design of PS-based NPs, and comprehensive insight into the potential of PS-based NPs used in multiple cancer therapies.

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.

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.

Drug Delivery by Ultrasound-Responsive Nanocarriers for Cancer Treatment

Conventional cancer chemotherapies often exhibit insufficient therapeutic outcomes and dose-limiting toxicity. Therefore, there is a need for novel therapeutics and formulations with higher efficacy, improved safety, and more favorable toxicological profiles. This has promoted the development of nanomedicines, including systems for drug delivery, but also for imaging and diagnostics. Nanoparticles loaded with drugs can be designed to overcome several biological barriers to improving efficiency and reducing toxicity. In addition, stimuli-responsive nanocarriers are able to release their payload on demand at the tumor tissue site, preventing premature drug loss. This review focuses on ultrasound-triggered drug delivery by nanocarriers as a versatile, cost-efficient, non-invasive technique for improving tissue specificity and tissue penetration, and for achieving high drug concentrations at their intended site of action. It highlights aspects relevant for ultrasound-mediated drug delivery, including ultrasound parameters and resulting biological effects. Then, concepts in ultrasound-mediated drug delivery are introduced and a comprehensive overview of several types of nanoparticles used for this purpose is given. This includes an in-depth compilation of the literature on the various in vivo ultrasound-responsive drug delivery systems. Finally, toxicological and safety considerations regarding ultrasound-mediated drug delivery with nanocarriers are discussed.

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.

Utilizing Stimuli Responsive Linkages to Engineer and Enhance Polymer Nanoparticle-Based Drug Delivery Platforms

The devastating nature of cancer continues to be one of the leading causes of death in the world. Chemotherapy is among the most common forms of cancer treatment but comes with a host of adverse effects caused by the therapeutic agents damaging healthy tissue and organs. To limit these side effects, scientists have been designing stimuli responsive drug delivery vessels for targeted release. This Review focuses on the incorporation of stimuli responsive linkages in targeted drug delivery systems to enhance therapeutic efficiency. These platforms are primarily employed to control the distribution of anticancer agents in the body to reduce the adverse side effects caused by their toxicities. We will outline how drug delivery vessels are constructed so that exposure to select environmental and external stimuli releases the enclosed drug only at the target site. Stimuli responsive components are integrated within drug delivery vessels in the form of cross-linkers, polymers, and surface modifications. The changes, these moieties undergo upon stimuli exposure, cascade into larger scale alterations to the platforms, resulting in complete disassembly, reversible morphological variations, and enhanced cellular uptake. The ability for these modes of delivery to be initiated exclusively under stimuli exposure allows for release of toxic therapeutic agents to be confined only to the affected area.

Bibliometric Analysis of Global Research Trends on Ultrasound Microbubble: A Quickly Developing Field

Background: Microbubbles are widely used as highly effective contrast agents to improve the diagnostic capability of ultrasound imaging. Mounting evidence suggests that ultrasound coupled with microbubbles has promising therapeutic applications in cancer, cardiovascular, and neurological disorders by acting as gene or drug carriers. The aim of this study was to identify the scientific output and activity related to ultrasound microbubble through bibliometric approaches. Methods: The literature related to ultrasound microbubble published between 1998 and 2019 was identified and selected from the Science Citation Index Expanded of Web of Science Core Collection on February 21, 2021. The Scopus database was also searched to validate the results and provided as supplementary material. Quantitative variables including number of publications and citations, H-index, and journal citation reports were analyzed by using Microsoft Excel 2019 and GraphPad Prism 8.0 software. VOS viewer and CiteSpace V were used to perform coauthorship, citation, co-citation, and co-occurrence analysis for countries/regions, institutions, authors, and keywords. Results: A total of 6088 publications from the WoSCC were included. The United States has made the largest contribution in this field, with the majority of publications (2090, 34.3%), citations (90,741, 46.6%), the highest H-index (138), and close collaborations with China and Canada. The most contributive institution was the University of Toronto. Professors De Jong N and Dayton P A have made great achievements in this field. However, the research cooperation between institutions and authors was relatively weak. All the studies could be divided into four clusters: "ultrasound diagnosis study," "microbubbles' characteristics study," "gene therapy study," and "drug delivery study." The average appearing years (AAY) of keywords in the cluster "drug delivery study" was more recent than other clusters. For promising hot spots, "doxorubicin" showed a relatively latest AAY of 2015.49, followed by "nanoparticles" and "breast cancer." Conclusion: There has been an increasing amount of scientific output on ultrasound microbubble according to the global trends, and the United States is staying ahead in this field. Collaboration between research teams still needs to be strengthened. The focus gradually shifts from "ultrasound diagnosis study" to "drug delivery study." It is recommended to pay attention to the latest hot spots, such as "doxorubicin," "nanoparticles," and "breast cancer."

Autophagy blockade synergistically enhances nanosonosensitizer-enabled sonodynamic cancer nanotherapeutics

Ultrasound-triggered sonodynamic therapy (SDT) represents an emerging therapeutic modality for cancer treatment based on its specific feature of noninvasiveness, high tissue-penetrating depth and desirable therapeutic efficacy, but the SDT-induced pro-survival cancer-cell autophagy would significantly lower the SDT efficacy for cancer treatment. Here we propose an "all-in-one" combined tumor-therapeutic strategy by integrating nanosonosensitizers-augmented noninvasive SDT with autophagy inhibition based on the rationally constructed nanoliposomes that co-encapsulates clinically approved sonosensitizers protoporphyrin IX (PpIX) and early-phase autophagy-blocking agent 3-methyladenine (3-MA). It has been systematically demonstrated that nanosonosensitizers-augmented SDT induced cytoprotective pro-survival autophagy through activation of MAPK signaling pathway and inhibition of AMPK signaling pathway, and this could be efficaciously inhibited by 3-MA in early-phase autophagy, which significantly decreased the cell resistance to intracellular oxidative stress and complied a remarkable synergistic effect on SDT medicated cancer-cell apoptosis both in vitro at cellular level and in vivo on tumor-bearing animal model. Therefore, our results provide a proof-of-concept combinatorial tumor therapeutics based on nanosonosensitizers for the treatment of ROS-resistant cancer by autophagy inhibition-augmented SDT.

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

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

Emerging Nanomedicine-Enabled/Enhanced Nanodynamic Therapies beyond Traditional Photodynamics

The rapid knowledge growth of nanomedicine and nanobiotechnology enables and promotes the emergence of distinctive disease-specific therapeutic modalities, among which nanomedicine-enabled/augmented nanodynamic therapy (NDT), as triggered by either exogenous or endogenous activators on nanosensitizers, can generate reactive radicals for accomplishing efficient disease nanotherapies with mitigated side effects and endowed disease specificity. As one of the most representative modalities of NDT, traditional light-activated photodynamics suffers from the critical and unsurmountable issues of the low tissue-penetration depth of light and the phototoxicity of the photosensitizers. To overcome these obstacles, versatile nanomedicine-enabled/augmented NDTs have been explored for satisfying varied biomedical applications, which strongly depend on the physicochemical properties of the involved nanomedicines and nanosensitizers. These distinctive NDTs refer to sonodynamic therapy (SDT), thermodynamic therapy (TDT), electrodynamic therapy (EDT), piezoelectric dynamic therapy (PZDT), pyroelectric dynamic therapy (PEDT), radiodynamic therapy (RDT), and chemodynamic therapy (CDT). Herein, the critical roles, functions, and biological effects of nanomedicine (e.g., sonosensitizing, photothermal-converting, electronic, piezoelectric, pyroelectric, radiation-sensitizing, and catalytic properties) for enabling the therapeutic procedure of NDTs, are highlighted and discussed, along with the underlying therapeutic principle and optimization strategy for augmenting disease-therapeutic efficacy and biosafety. The present challenges and critical issues on the clinical translations of NDTs are also discussed and clarified.

Ultrasonic Interfacial Engineering of Red Phosphorous-Metal for Eradicating MRSA Infection Effectively

Sonodynamic therapy (SDT) is considered to be a potential treatment for various diseases including cancers and bacterial infections due to its deep penetration ability and biosafety, but its SDT efficiency is limited by the hypoxia environment of deep tissues. This study proposes creating a potential solution, sonothermal therapy, by developing the ultrasonic interfacial engineering of metal-red phosphorus (RP), which has an obviously improved sonothermal ability of more than 20 °C elevation under 25 min of continuous ultrasound (US) excitation as compared to metal alone. The underlying mechanism is that the mechanical energy of the US activates the motion of the interfacial electrons. US-induced electron motion in the RP can efficiently transfer the US energy into phonons in the forms of heat and lattice vibrations, resulting in a stronger US absorption of metal-RP. Unlike the nonspecific heating of the cavitation effect induced by US, titanium-RP can be heated in situ when the US penetrates through 2.5 cm of pork tissue. In addition, through a sonothermal treatment in vivo, bone infection induced by multidrug-resistant Staphylococcus aureus (MRSA) is successfully eliminated in under 20 min of US without tissue damage. This work provides a new strategy for combating MRSA by strong sonothermal therapy through US interfacial engineering.

Recent advances in phase change material based nanoplatforms for cancer therapy

Cancer has become a severe threat to human life due to its high mortality and metastatic rate. Effective inhibition and killing of cancer cells using chemotherapeutic drugs have been a promising means in clinical cancer therapy. However, the low selectivity, drug-resistance, uncontrollability and serious side effects of chemotherapy significantly limit its further development. There is an urgent need for new treatment strategies to compensate for deficiencies inherent in chemotherapy alone. A growing body of research shows that combined treatment strategies have the potential to overcome this dilemma by achieving significantly enhanced synergistic effects and reduced side effects. Emerging phase change materials (PCMs) create an ideal nanoplatform for cancer combination therapy due to their universal loading properties, stable and temperature-responsive phase transition capability, and excellent natural biocompatibility/biodegradability. The release of therapeutic agents can be precisely controlled through external, non-intrusive stimuli (such as NIR light and ultrasound), avoiding systemic toxicity associated with conventional chemotherapy. Herein, the construction methods and design principles of PCM-based nanoplatforms serving as strict gatekeeper and smart payload delivery systems are discussed in detail. Moreover, the advantages and disadvantages of these nanoplatforms are provided. A suitable discussion and perspective of the remaining challenges and future opportunities for PCM-based nanoplatforms in cancer treatment are also given in conclusion.

Current status of targeted microbubbles in diagnostic molecular imaging of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is often associated with a poor prognosis due to silent onset, resistance to therapies, and rapid spreading. Most patients are ineligible for curable surgery as they present with advanced disease at the time of diagnosis. Present diagnostic methods relying on anatomical changes have various limitations including difficulty to discriminate between benign and malignant conditions, invasiveness, the ambiguity of imaging results, or the inability to detect molecular biomarkers of PDAC initiation and progression. Therefore, new imaging technologies with high sensitivity and specificity are critically needed for accurately detecting PDAC and noninvasively characterizing molecular features driving its pathogenesis. Contrast enhanced targeted ultrasound (CETUS) is an upcoming molecular imaging modality that specifically addresses these issues. Unlike anatomical imaging modalities such as CT and MRI, molecular imaging using CETUS is promising for early and accurate detection of PDAC. The use of molecularly targeted microbubbles that bind to neovascular targets can enhance the ultrasound signal specifically from malignant PDAC tissues. This review discusses the current state of diagnostic imaging modalities for pancreatic cancer and places a special focus on ultrasound targeted-microbubble technology together with its clinical translatability for PDAC detection.

Current update on nanoplatforms as therapeutic and diagnostic tools: A review for the materials used as nanotheranostics and imaging modalities

In the last decade, the use of nanotheranostics as emerging diagnostic and therapeutic tools for various diseases, especially cancer, is held great attention. Up to date, several approaches have been employed in order to develop smart nanotheranostics, which combine bioactive targeting on specific tissues as well as diagnostic properties. The nanotheranostics can deliver therapeutic agents by concomitantly monitor the therapy response in real-time. Consequently, the possibility of over- or under-dosing is decreased. Various non-invasive imaging techniques have been used to quantitatively monitor the drug delivery processes. Radiolabeling of nanomaterials is widely used as powerful diagnostic approach on nuclear medicine imaging. In fact, various radiolabeled nanomaterials have been designed and developed for imaging tumors and other lesions due to their efficient characteristics. Inorganic nanoparticles as gold, silver, silica based nanomaterials or organic nanoparticles as polymers, carbon based nanomaterials, liposomes have been reported as multifunctional nanotheranostics. In this review, the imaging modalities according to their use in various diseases are summarized, providing special details for radiolabeling. In further, the most current nanotheranostics categorized via the used nanomaterials are also summed up. To conclude, this review can be beneficial for medical and pharmaceutical society as well as material scientists who work in the field of nanotheranostics since they can use this research as guide for producing newer and more efficient nanotheranostics.

Mucin-16 targeted mesoporous nano-system for evaluation of cervical cancer via dual-modal computed tomography and ultrasonography

Mesoporous silica-coated bismuth nanoparticles (NPs) are dual-modal contrast agents that enable detection and quantification of cervical cancers at early stages using computed tomography (CT) and ultrasonography (US).

The Coppery Age: Copper (Cu)-Involved Nanotheranostics

As an essential trace element in the human body, transitional metal copper (Cu) ions are the bioactive components within the body featuring dedicated biological effects such as promoting angiogenesis and influencing lipid/glucose metabolism. The recent substantial advances of nanotechnology and nanomedicine promote the emerging of distinctive Cu-involved biomaterial nanoplatforms with intriguing theranostic performances in biomedicine, which are originated from the biological effects of Cu species and the physiochemical attributes of Cu-composed nanoparticles. Based on the very-recent significant progresses of Cu-involved nanotheranostics, this work highlights and discusses the principles, progresses, and prospects on the elaborate design and rational construction of Cu-composed functional nanoplatforms for a diverse array of biomedical applications, including photonic nanomedicine, catalytic nanotherapeutics, antibacteria, accelerated tissue regeneration, and bioimaging. The engineering of Cu-based nanocomposites for synergistic nanotherapeutics is also exemplified, followed by revealing their intrinsic biological effects and biosafety for revolutionizing their clinical translation. Finally, the underlying critical concerns, unresolved hurdles, and future prospects on their clinical uses are analyzed and an outlook is provided. By entering the "Copper Age," these Cu-involved nanotherapeutic modalities are expected to find more broad biomedical applications in preclinical and clinical phases, despite the current research and developments still being in infancy.

Engineering two-dimensional silicene composite nanosheets for dual-sensitized and photonic hyperthermia-augmented cancer radiotherapy

The rapid development of nanotechnology has triggered the emerging of tremendous theranostic nanoplatforms for combating cancers. Silicene, as an emerging two-dimensional (2D) material, has been recently explored as therapeutic agent due to their desirable biodegradation and strong photothermal-conversion performance. However, the rational design of silicene-based composites for further exerting multifunctional medical applications is still highly challenging. Herein, we report on the construction of silicene-based silicene@Pt composite nanosheets for computed tomography (CT)/photoacoustic (PA) imaging-guided dual-sensitized radiotherapy combined with photonic tumor hyperthermia, which has been achieved by a seed-growth approach to in situ grow Pt components onto silicene nanosheets' surface. Especially, by functionalization of Pt components, these nanosheets could act as both contrast agents for CT imaging and dual radio-sensitizing agents for radiotherapy, which could deposit Pt-involved radiation energy (sensitized therapeutic process I) and overcome hypoxia-associated radio-resistance by Pt-catalytic O₂ generation from overexpressed H₂O₂ within the tumor microenvironment (sensitized therapeutic process II). The strong photothermal-conversion performance of silicene nanosheets not only endowed silicene@Pt composite nanosheets with photoacoustic imaging property, but also realized the photonic tumor hyperthermia and achieved a combined therapeutic effect with radiotherapy. This work not only broadens the biomedical applications of silicene, but also develops functionalization strategies of silicene for versatile biomedical applications.