Drug Delivery by Ultrasound-Responsive Nanocarriers for Cancer Treatment

External stimuli-responsive drug delivery to the posterior segment of the eye

Posterior segment eye diseases represent the leading causes of vision impairment and blindness globally. Current therapies still have notable drawbacks, including the need for frequent invasive injections and the associated risks of severe ocular complications. Recently, the utility of external stimuli, such as light, ultrasound, magnetic field, and electric field, has been noted as a promising strategy to enhance drug delivery to the posterior segment of the eye. In this review, we briefly summarize the main physiological barriers against ocular drug delivery, focusing primarily on the recent advancements that utilize external stimuli to improve treatment outcomes for posterior segment eye diseases. The advantages of these external stimuli-responsive drug delivery strategies are discussed, with illustrative examples highlighting improved tissue penetration, enhanced control over drug release, and targeted drug delivery to ocular lesions through minimally invasive routes. Finally, we discuss the challenges and future perspectives in the translational research of external stimuli-responsive drug delivery platforms, aiming to bridge existing gaps toward clinical use.

Mechanistic study of cancer drug delivery: Current techniques, limitations, and future prospects

Cancer drug delivery remains a critical challenge with systemic toxicity, poor drug bioavailability, and a lack of effective targeting. Overcoming these barriers is essential for improving treatment efficacy and patient outcomes. This review discusses current drug delivery techniques that reshape cancer therapy by offering precise, controlled-release tailored to tumor-specific features. Innovations in nanotechnology, immunotherapy, and gene therapy enable interventions at molecular and cellular levels. Radiomics and pathomics integrate high-dimensional data to optimize diagnostics and treatment planning. Combination therapy addresses the complexities of tumor heterogeneity by synergizing multiple agents within a single therapeutic framework, while peptide-drug conjugates enhance specificity and potency. Hydrogel-based systems and microneedle arrays offer localized, sustained release, significantly improving therapeutic outcomes. However, clinical translation of these advancements faces significant barriers such as drug resistance, off-target effects, scalability, cost, and ethical concerns. Moreover, regulatory complexities and the economic feasibility of these therapies highlight the need for innovative frameworks to make them accessible globally. Therefore, there is a need for innovation in gene and cell therapy, next-generation drug delivery platforms, and personalized medicine. This review focuses on recent advancements in drug delivery techniques over the past decade, evaluating their limitations and exploring potential future directions for transforming cancer treatment.

Experimental studies on squeezing interstitial fluid via transfer of ultrasound momentum (SIF-TUM) in ex vivo chicken and porcine tissues

The ultrasound-assisted transport of drugs or fluorophore-loaded nanoagents plays an important role in the desirable drug delivery and imaging contrasts. Unlike conventional ultrasound techniques that rely on thermal or cavitation effects, this study aims to conduct an experimental investigation into the dynamics of interstitial fluid streaming and tissue recovery in ex vivo chicken breast and porcine loin muscle tissues during and after ultrasound exposures, which has not been experimentally investigated in the literature. Biological tissues consist of both a fluid and a solid matrix, and an ultrasound beam compresses the tissues within a small focal volume from all directions, which generates macroscopic streaming of interstitial fluid and compression of the tissue's solid matrix. After the ultrasonic exposure, the solid matrix undergoes recovery, leading to a backflow of the fluid matrix. Temperature-insensitive sulforhodamine-101 encapsulated poly(lactic-co-glycolic acid) nanoparticles with an average diameter size of 175 nm were locally injected into ex vivo chicken breast and porcine loin muscle tissues to study the ultrasound-induced dynamics in the tissues during and after ultrasound exposure by analyzing the distribution of fluorescence. The changes in fluorescence over time caused by the streaming and backflow of interstitial fluid were studied with two ex vivo tissue models, and a faster recovery was observed in porcine tissues compared with chicken tissues. The ultrasound-induced transportability of the nanoagent in porcine muscle tissues was much higher (∼8.75 times) than in chicken breast tissue likely due to structural differences. The study reveals a promising, non-invasive strategy for enhancing drug delivery in dense tissues by leveraging mechanical ultrasound effects, potentially advancing therapeutic and diagnostic applications.

Branched silver-iron oxide nanoparticles enabling highly effective targeted and localised drug-free thrombolysis

Ultrasound has been widely used as an external stimulus to trigger drug release from nanomaterials in thrombosis treatment. Here, we introduce a novel strategy leveraging nanomaterials not for drug delivery, but for enhancing US-induced thrombolysis. This innovative strategy is particularly significant, as thrombolytic drugs inherently pose a risk of systemic bleeding. We combined branched silver-iron oxide nanoparticles (AgIONPs) with low-intensity focused ultrasound to evaluate their thrombolytic potential. Binding assays in in vitro human blood clots and in a thrombosis mouse model confirmed that the targeted AgIONPs specifically bound to thrombi. Upon ultrasound activation, AgIONPs facilitated thrombolysis via two key mechanisms: hyperthermia driven by the nanoparticle-mediated thermal conversion, and mechanical shear forces induced by ultrasound. The combination of AgIONPs and US generated a synergistic thrombolytic effect, demonstrating significant efficacy in both in vitro and in vivo.

Ultrasound-mediated nanomaterials for the treatment of inflammatory diseases

Sterile and infection-associated inflammatory diseases are becoming increasingly prevalent worldwide. Conventional drug therapies often entail significant drawbacks, such as the risk of drug overdose, the development of drug resistance in pathogens, and systemic adverse reactions, all of which can undermine the effectiveness of treatments for these conditions. Nanomaterials (NMs) have emerged as a promising tool in the treatment of inflammatory diseases due to their precise targeting capabilities, tunable characteristics, and responsiveness to external stimuli. Ultrasound (US), a non-invasive and effective treatment method, has been explored in combination with NMs to achieve enhanced therapeutic outcomes. This review provides a comprehensive overview of the recent advances in the use of US-mediated NMs for treating inflammatory diseases. A comprehensive introduction to the application and classification of US was first presented, emphasizing the advantages of US-mediated NMs and the mechanisms through which US and NMs interact to enhance anti-inflammatory therapy. Subsequently, specific applications of US-mediated NMs in sterile and infection-associated inflammation were summarized. Finally, the challenges and prospects of US-mediated NMs in clinical translation were discussed, along with an outline of future research directions. This review aims to provide insights to guide the development and improvement of US-mediated NMs for more effective therapeutic interventions in inflammatory diseases.

Combined Albumin Polyester Nanocarriers with Docetaxel for Effective Against Lung Cancer in Mice Model

Introduction

Lung cancer, a deadly malignancy, often employs Docetaxel (DTX) as a chemotherapy option. However, DTX non-selective distribution limits its therapeutic effectiveness due to adverse side effects. This study aims to develop novel folate-targeted albumin polyester nanocarriers (FA-DTX-APs) encapsulating DTX for precise delivery, enhancing lung cancer treatment efficacy.

Methods

FA-DTX-APs were meticulously crafted utilizing the thin-film dispersion technique and subsequently evaluated for their physicochemical characteristics, encapsulation efficiency, and drug release profiles. To assess their biological properties, anti-tumor efficacy, and biosafety in the context of lung cancer, a comprehensive series of hemolysis assays, cellular studies, and animal experiments were conducted.

Results

FA-DTX-APs exhibit nanovesicle properties with a size of (223.65 ± 6.83) nm, a potential of (26.76 ± 3.15) mV, and encapsulate DTX with high efficiency (96.19 ± 3.27%) and loading capacity (9.75 ± 0.38%). FA-DTX-APs enable tumor-targeted drug delivery and slow release of the drug over a long period of time, with faster release in acidic environments. By efficiently targeting and entering lung cancer cells, FA-DTX-APs effectively hinder cancer growth (P < 0.05), demonstrating superior anti-tumor effects (P < 0.05), biocompatibility and enhanced biological safety (P < 0.05).

Conclusion

This study introduces FA-DTX-APs, an innovative nanocarrier characterized by exceptional biocompatibility and safety. It successfully targets lung cancer cells to deliver DTX in a sustained, slow-release manner, ensuring prolonged tumor-killing effects. As such, FA-DTX-APs hold immense promise as a novel nanoagent for lung cancer therapy.

Stimuli-responsive mesoporous silica nanoplatforms for smart antibacterial therapies: From single to combination strategies

The demand for new antibacterial therapies is urgent and crucial in the clinical setting because of the growing degree of antibiotic resistance and the limits of conventional antibacterial therapies. Stimuli- responsive nanoplatforms, are sensitive to endogenous or exogenous stimulus (pH, temperature, light, and magnetic fields, etc.) which activate cargo release locally and on-demand, hold great potential in developing next generation personalized precision medicine. For instance, pH-sensitive nanoplatforms can selectively release antibacterial agents in the acidic environment of infection sites. To achieve the stimuli-responsive delivery, mesoporous silica nanoplatforms (MSNs) have demonstrated as prospective candidates for efficient cargo loading and controlled release through strategies such as tunable pore engineering, versatile surface modification/coating, and tailored framework composition. Furthermore, aiming for more precise delivery of MSNs, current research interests are increasingly shifting from single-stimuli antibacterial strategy to integrated strategy that combine multiple-stimulus. In this review, we briefly discuss the microenvironment of bacterial infections and provide a comprehensive summary of current stimuli-responsive strategies, and associated materials design principles of stimuli-responsive mesoporous silica-based smart nanoplatforms (SRMSNs). Additionally, integrative antibacterial strategies with synergistic effects, combining chemodynamic, photodynamic, photothermal, sonodynamic and gas therapies, have also been elaborated. Present research advances and limitations of SRMSNs-based antibacterial therapies, such as limited biodegradability and potential cytotoxicity, have been overviewed with future outlooks presented. This review aims to inspire and guide future research in developing novel antibacterial strategies with integrative solutions.

Advances in Ultrasound-Targeted Microbubble Destruction (UTMD) for Breast Cancer Therapy

Breast cancer is one of the most common types of cancer in women worldwide and is a leading cause of cancer deaths among women. As a result, various treatments have been developed to combat this disease. Breast cancer treatment varies based on its stage and type of pathology. Among the therapeutic options, ultrasound has been employed to assist in the treatment of breast cancer, including radiation therapy, chemotherapy, targeted immunotherapy, hormonal therapy, and, more recently, radiofrequency ablation for early-stage and inoperable patients. One notable advancement is ultrasound-targeted microbubble destruction (UTMD), which is gradually becoming a highly effective and non-invasive anti-tumor modality. This technique can enhance chemical, genetic, immune, and anti-vascular therapies through its physical and biological effects. Specifically, UTMD improves drug transfer efficiency and destroys tumor neovascularization while reducing toxic side effects on the body during tumor treatment. Given these developments, the application of ultrasound-assisted therapy to breast cancer has gained significant attention from research scholars. In this review, we will discuss the development of various therapeutic modalities for breast cancer and, importantly, highlight the application of ultrasound microbubble-targeted disruption techniques in breast cancer treatment.

The effect of temperature constraints on the treatment of tumors using focused ultrasound-induced acoustic streaming

The transport of drugs into tumor cells near the center of the tumor is known to be severely hindered due to the high interstitial pressure and poor vascularization. The aim of this work is to investigate the possibility to induce acoustic streaming in a tumor. Two tumor cases (breast and abdomen) are simulated to find the acoustic streaming and temperature rise, while varying the focused ultrasound transducer radius, frequency, and power for a constant duty cycle (1%). In the absence of perfusion, the simulated rise in temperature, despite the low duty cycle, never reaches a steady state and is fitted to a logarithmic equation, enabling predictions of the temperature for long treatment times. Higher frequencies and larger probe radii are found to result in shorter treatment times relative to the temperature rise, at the cost of a smaller treated area. Results from the simulations indicate that it may be possible to achieve reasonable acoustic streaming values in tumor without the temperature exceeding 50 °C. Treatment times for streaming a distance of 50 μm in the breast case are shown to range from less than one and a half hour to 93 h, depending on the probe settings.

Application of nanoultrasonography in early diagnosis of coronary heart disease

Coronary heart disease (CHD) remains one of the leading causes of mortality and disability globally. In recent years, nanoultrasonography technology has demonstrated significant potential in both the diagnosis and treatment of CHD. This review summarizes the latest research advancements in nanoultrasonography within the field of coronary heart disease, focusing on its applications in early diagnosis, targeted drug delivery, imaging techniques, and treatment strategies. We explore the working principles of nanoultrasonography, its technological advantages, and the challenges faced in clinical applications. The aim is to provide guidance for future research and clinical practice in this promising area.

Intelligent Drug Delivery: Pioneering Stimuli-Responsive Systems to Revolutionize Disease Management- An In-depth Exploration

In recent years, there has been an escalating interest in stimuli-responsive drug delivery systems (SRDDS) due to their ability to revolutionize the delivery of therapeutics. SRDDSs offer a multitude of benefits in comparison to conventional drug delivery systems (DDS), including spatiotemporal control of drug release, targeted delivery, and improved therapeutic efficacy. The development of various classes of stimuli-responsive DDS, such as pH-responsive, temperature-responsive, photo-responsive, redox responsive systems, has been propelled by advances in materials science, nanotechnology, and biotechnology. These systems exploit specific environmental or physiological cues to trigger drug release in a precisely controlled manner, making them highly promising for the treatment of various diseases. In this review article, an in-depth exploration of the principles, mechanisms, and applications of SRDDS in the context of diverse pathologies such as cancer, arthritis, Alzheimer's disease, atherosclerosis and tissue engineering has been provided. Furthermore, this article delves into the discussion of recent patents, market overview and the progress of research in clinical trials. Overall, this article underscores the transformative potential of SRDDS in enabling personalized, precise, and effective drug delivery for the treatment of the above-mentioned diseases.

Smart Ultrasound-responsive Polymers for Drug Delivery: An Overview on Advanced Stimuli-sensitive Materials and Techniques

In recent years, a notable advancement has occurred in the domain of drug delivery systems via the integration of intelligent polymers that respond to ultrasound. The implementation of this groundbreaking methodology has significantly revolutionised the controlled and precise delivery of therapeutic interventions. An in-depth investigation is conducted into the most recent developments in ultrasonic stimulus-responsive materials and techniques for the purpose of accomplishing precise medication administration. The investigation begins with an exhaustive synopsis of the foundational principles underlying drug delivery systems that react to ultrasonic stimuli, focusing specifically on the complex interplay between polymers and ultrasound waves. Significant attention is devoted to the development of polymers that demonstrate tailored responsiveness to ultrasound, thereby exemplifying their versatility in generating controlled drug release patterns. Numerous classifications of intelligent polymers are examined in the discussion, including those that react to variations in temperature, pH, and enzymes. When coupled with ultrasonic stimuli, these polymers offer a sophisticated framework for the precise manipulation of drug release in terms of both temporal and spatial dimensions. The present study aims to examine the synergistic effects of responsive polymers and ultrasound in overcoming biological barriers such as the blood-brain barrier and the gastrointestinal tract. By doing so, it seeks to shed light on the potential applications of these materials in intricate clinical scenarios. The issues and future prospects of intelligent ultrasound-responsive polymers in the context of drug delivery are critically analysed in this article. The objective of this study is to offer valuable perspectives on the challenges that must be overcome to enable the effective implementation of these technologies. The primary objective of this comprehensive review is to furnish researchers, clinicians, and pharmaceutical scientists with a wealth of information that will serve as a guide for forthcoming developments in the development and enhancement of intelligent drug delivery systems that employ ultrasound-responsive polymers to attain superior therapeutic outcomes.

Innovative Approaches to Brain Cancer: The Use of Magnetic Resonance-guided Focused Ultrasound in Glioma Therapy

Gliomas are a wide group of common brain tumors, with the most aggressive type being glioblastoma multiforme (GBM), with a 5-year survival rate of less than 5% and a median survival time of approximately 12-14 months. The standard treatment of GBM includes surgical excision, radiotherapy, and chemotherapy with temozolomide (TMZ). However, tumor recurrence and progression are common. Therefore, more effective treatment for GBM should be found. One of the main obstacles to the treatment of GBM and other gliomas is the blood-brain barrier (BBB), which impedes the penetration of antitumor chemotherapeutic agents into glioblastoma cells. Nowadays, one of the most promising novel methods for glioma treatment is Magnetic Resonance-guided Focused Ultrasound (MRgFUS). Low-intensity FUS causes the BBB to open transiently, which allows better drug delivery to the brain tissue. Under magnetic resonance guidance, ultrasound waves can be precisely directed to the tumor area to prevent side effects in healthy tissues. Through the open BBB, we can deliver targeted chemotherapeutics, anti-tumor agents, immunotherapy, and gene therapy directly to gliomas. Other strategies for MRgFUS include radiosensitization, sonodynamic therapy, histotripsy, and thermal ablation. FUS can also be used to monitor the treatment and progression of gliomas using blood-based liquid biopsy. All these methods are still under preclinical or clinical trials and are described in this review to summarize current knowledge and ongoing trials.

An investigation of quantum dot theranostic probes for prostate and leukemia cancer cells using a CdZnSeS QD-based nanoformulation

Anticancer theranostic nanocarriers have the potential to enhance the efficacy of pharmaceutical evaluation of drugs. Semiconductor nanocrystals, also known as quantum dots (QDs), are particularly promising components of drug carrier systems due to their small sizes and robust photoluminescence properties. Herein, bright CdZnSeS quantum dots were synthesized in a single step via the hot injection method. The particles have a quasi-core/shell structure as evident from the high quantum yield (85 %), which decreased to 41 % after water solubilization. These water solubilized QDs were encapsulated into gallic acid / alginate (GA-Alg) matrices to fabricate imaging QDs@mod-PAA/GA-Alg particles with enhanced stability in aqueous media. Cell viability assessments demonstrated that these nanocarriers exhibited viability ranging from 63 % to 83 % across all tested cell lines. Furthermore, the QDs@mod-PAA/GA-Alg particles were loaded with betulinic acid (BA) and ceranib-2 (C2) for in vitro drug release studies against HL-60 leukemia and PC-3 prostate cancer cells. The BA loaded QDs@mod-PAA/GA-Alg had a half-maximal inhibitory concentration (IC50) of 8.76 μg/mL against HL-60 leukemia cells, which is 3-fold lower than that of free BA (IC50 = 26.55 μg/mL). Similar enhancements were observed with nanocarriers loaded with C2 and simultaneously with both BA and C2. Additionally, BA:C2 loaded QDs@mod-PAA/GA-Alg nanocarriers displayed a similar enhancement (IC50 = 3.37 μg/mL compared against IC50 = 11.68 μg/mL for free BA:C2). The C2 loaded QDs@mod-PAA/GA-Alg nanocarriers had an IC50 = 2.24 μg/mL against HL-60 cells. C2 and BA loaded QDs@mod-PAA/GA-Alg NCr had IC50 values of 7.37 μg/mL and 24.55 μg/mL against PC-3 cells, respectively.

Research progress of paclitaxel nanodrug delivery system in the treatment of triple-negative breast cancer

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, characterized by the loss or low expression of estrogen receptor (ER), human epidermal growth factor receptor 2 (HER2) and progesterone receptor (PR). Due to the lack of clear therapeutic targets, paclitaxel (PTX) is often used as a first-line standard chemotherapy drug for the treatment of high-risk and locally advanced TNBC. PTX is a diterpenoid alkaloid extracted and purified from Taxus plants, functioning as an anticancer agent by inducing and promoting tubulin polymerization, inhibiting spindle formation in cancer cells, and preventing mitosis. However, its clinical application is limited by low solubility and high toxicity. Nanodrug delivery system (NDDS) is one of the feasible methods to improve the water solubility of PTX and reduce side effects. In this review, we summarize the latest advancements in PTX-targeted NDDS, as well as its combination with other codelivery therapies for TNBC treatment. NDDS includes passive targeting, active targeting, stimuli-responsive, codelivery, and multimode strategies. These systems have good prospects in improving the bioavailability of PTX, enhancing tumor targeting, reducing toxicity, controlling drug release, and reverse tumor multidrug resistance (MDR). This review provides valuable insights into the clinical development and application of PTX-targeted NDDS in the treatment of TNBC.

Low-Intensity Continuous Ultrasound Enhances the Therapeutic Efficacy of Curcumin-Encapsulated Exosomes Derived from Hypoxic Liver Cancer Cells via Homotropic Drug Delivery Systems

Exosomes are extracellular nanovesicles secreted by cells that efficiently deliver therapeutic cargo for cancer treatment. However, because exosomes are present in low quantities and have limited target specificity, internal and external stress stimulation has been studied to increase exosome efficiency. Inspired by these studies, the uptake efficiency of cobalt chloride-induced hypoxic cancer cell-secreted exosomes was evaluated. Western blotting and RT-PCR data revealed increased exosome secretion and different protein compositions exhibited by hypoxic exosomes (H-Exos) compared to natural normoxic exosomes (N-Exos). Furthermore, these H-Exos were continuously stimulated using low-intensity ultrasound (LICUS) at an intensity of 360 mW/cm2 and a frequency of 3 MHz in vitro and 1 MHz in vivo. Hyperthermic and mechanical stress caused by ultrasound successfully improved exosome uptake via clathrin-mediated pathways, and confocal laser microscopy showed strong internal localization near the target cell nuclei. Finally, LICUS-equipped H-Exos were loaded with hydrophobic curcumin (H-Exo-Cur) and used to treat parent HepG2 liver cancer cells. The UV-Vis spectrophotometer displayed enhanced stability, solubility, and concentration of the encapsulated drug molecules. In MTT and FACS studies, approximately 40 times higher cell death was induced, and in animal studies, approximately 10 times higher tumor sizes were suppressed by LICUS-assisted H-Exo-Cur compared to the control. In this study, the delivery platform constructed demonstrated enormous potential for liver cancer therapy.

Drug Release via Ultrasound-Activated Nanocarriers for Cancer Treatment: A Review

Conventional cancer chemotherapy often struggles with safely and effectively delivering anticancer therapeutics to target tissues, frequently leading to dose-limiting toxicity and suboptimal therapeutic outcomes. This has created a need for novel therapies that offer greater efficacy, enhanced safety, and improved toxicological profiles. Nanocarriers are nanosized particles specifically designed to enhance the selectivity and effectiveness of chemotherapy drugs while reducing their toxicity. A subset of drug delivery systems utilizes stimuli-responsive nanocarriers, which enable on-demand drug release, prevent premature release, and offer spatial and temporal control over drug delivery. These stimuli can be internal (such as pH and enzymes) or external (such as ultrasound, magnetic fields, and light). This review focuses on the mechanics of ultrasound-induced drug delivery and the various nanocarriers used in conjunction with ultrasound. It will also provide a comprehensive overview of key aspects related to ultrasound-induced drug delivery, including ultrasound parameters and the biological effects of ultrasound waves.

Incorporation of CuS nanorods in polyelectrolyte multilayer microcapsules improved cancer cell cytotoxicity and signal intensity in ultrasound imaging

The fabrications of hollow microcapsules (MCs) with new architecture and ability to incorporate different nanomaterials have received great interest for targeted cancer therapy. Recently, CuS based nanomaterials have been demonstrated to possess the ability to mimic Fenton-like activity in tumor environment and inducing cancer cell apoptosis by generating highly reactive oxygen species (ROS). In this study, we have developed poly(allylamine) hydrochloride (PAH)/dextran sulfate (DS) polyelectrolyte MCs capable of carrying doxorubicin (DOX) for targeted cancer therapy and ultrasound imaging. The electron microscopy investigations showed the formation of polymeric MCs of 3 µm in size with incorporated CuS NRs in their interior structure. The surface modification of MCs with folic acid (FA), and encapsulation of model hydrophilic molecules in MCs was studied by UV-Visible (UV-Vis) spectroscopy, Fourier transform infra-red (FTIR) spectroscopy and confocal laser scanning microscopy. The encapsulation efficiency of DOX was found to be 56 % and the release was found to be linear at pH 5.5 and 7.4 in the absence of ultrasound exposure. The ultrasound exposure resulted in sudden rupture of MCs at 1 MHz and 1 W/cm2 and caused burst release of DOX at both pH conditions. The FA decorated PAH/DS/CuS NR MCs exhibited improved anti-cancer activity against MDA-MB-231 cancer cells due to the synergistic effects of ultrasound mediated burst release of chemotherapeutic drug (DOX), glutathione-stimulated ROS and targeted cancer therapy. Further, the capsules showed better echogenicity than that of control PAH/DS MCs when imaged under medical ultrasound-scanning system. Hence, the MCs demonstrated in this study have huge potential for targeted cancer theranostics by offering an option to image the cancer cells during the treatment period.

Ultrasonic nanotechnology for the effective management of Staphylococcus aureus skin infections: an update

Ultrasonic nanotechnology represents a groundbreaking advancement in the management of Staphylococcus aureus skin infections, addressing the significant limitations of conventional treatments. S. aureus poses substantial challenges, including antibiotic resistance and biofilm formation, necessitating novel and effective approaches. By harnessing the power of ultrasonic waves and nanostructures, this technology offers a precise mechanism to disrupt bacterial cells, enhancing antibiotic susceptibility and facilitating the eradication of bacterial colonies. This innovative approach not only improves treatment outcomes, but also offers a non-invasive and highly efficient alternative to traditional methods. Recent studies have demonstrated the remarkable efficacy of ultrasonic nanotechnology, showcasing its ability to revolutionize the treatment paradigm for S. aureus infections. Ongoing research is dedicated to refining treatment protocols, developing new nanostructures, and assessing clinical applicability, with a focus on overcoming challenges such as scalability and long-term effectiveness. This review provides a comprehensive overview of the current state of ultrasonic nanotechnology in combating S. aureus skin infections, detailing its mechanism of action, summarizing key research findings, and highlighting its superiority over conventional modalities. Accumulating evidence underscores its potential as a pivotal development in modern science and technology, promising significant advancements in infection management strategies. As research continues to evolve, the optimization of protocols, exploration of innovative applications, and translation into clinical practice are poised to further solidify the transformative impact of ultrasonic nanotechnology in the medical field.

Recent Update on Nanocarrier(s) as the Targeted Therapy for Breast Cancer

Despite ongoing advances in cancer therapy, the results for the treatment of breast cancer are not satisfactory. The advent of nanotechnology promises to be an essential tool to improve drug delivery effectiveness in cancer therapy. Nanotechnology provides an opportunity to enhance the treatment modality by preventing degradation, improving tumour targeting, and controlling drug release. Recent advances have revealed several strategies to prevent cancer metastasis using nano-drug delivery systems (NDDS). These strategies include the design of appropriate nanocarriers loaded with anti-cancer drugs that target the optimization of physicochemical properties, modulate the tumour microenvironment, and target biomimetic techniques. Nanocarriers have emerged as a preferential approach in the chemotropic treatment for breast cancer due to their pivotal role in safeguarding the therapeutic agents against degradation. They facilitate efficient drug concentration in targeted cells, surmount the resistance of drugs, and possess a small size. Nevertheless, these nanocarrier(s) have some limitations, such as less permeability across the barrier and low bioavailability of loaded drugs. To overcome these challenges, integrating external stimuli has been employed, encompassing infrared light, thermal stimulation, microwaves, and X-rays. Among these stimuli, ultrasound-triggered nanocarriers have gained significant attention due to their cost-effectiveness, non-invasive nature, specificity, ability to penetrate tissues, and capacity to deliver elevated drug concentrations to intended targets. This article comprehensively reviews recent advancements in different nanocarriers for breast cancer chemotherapy. It also delves into the associated hurdles and offers valuable insights into the prospective directions for this innovative field.

Recent Progress in Implantable Drug Delivery Systems

In recent years, tremendous effort is devoted to developing platforms, such as implantable drug delivery systems (IDDSs), with temporally and spatially controlled drug release capabilities and improved adherence. IDDSs have multiple advantages: i) the timing and location of drug delivery can be controlled by patients using specific stimuli (light, sound, electricity, magnetism, etc.). Some intelligent "closed-loop" IDDS can even realize self-management without human participation. ii) IDDSs enable continuous and stable delivery of drugs over a long period (months to years) and iii) to administer drugs directly to the lesion, thereby helping reduce dosage and side effects. iv) IDDSs enable personalized drug delivery according to patient needs. The high demand for such systems has prompted scientists to make efforts to develop intelligent IDDS. In this review, several common stimulus-responsive mechanisms including endogenous (e.g., pH, reactive oxygen species, proteins, etc.) and exogenous stimuli (e.g., light, sound, electricity, magnetism, etc.), are given in detail. Besides, several types of IDDS reported in recent years are reviewed, including various stimulus-responsive systems based on the above mechanisms, radio frequency-controlled IDDS, "closed-loop" IDDS, self-powered IDDS, etc. Finally, the advantages and disadvantages of various IDDS, bottleneck problems, and possible solutions are analyzed to provide directions for subsequent research.

Tumor suppression effect of ultrasound-sensitive nanoparticles with focused ultrasound in a pancreas cancer xenograft model

BACKGROUND

We investigated the tumor suppression effect of an ultrasound-sensitive doxorubicin-loaded liposome-based nanoparticle, IMP301, to enhance the synergistic effect with focused ultrasound (FUS) in an animal model of pancreatic cancer.

METHODS

Thirty nude mice with xenografts of PANC-1 human pancreatic cancer cells were randomly and prospectively allocated to 6 different groups (5 per group) each for Study-1 (dose-response test) and Study-2 (synergistic effect test). Study-1 consisted of control, gemcitabine, Doxil with FUS, and three different doses of IMP301 (2, 4, 6 mg/kg) with FUS groups. Study-2 consisted of control, FUS only, gemcitabine, Doxil with FUS, and IMP301 (4 mg/kg) with or without FUS groups. Differences in tumor volume and growth rate were evaluated by one-way ANOVA and Student-Newman-Keuls test.

RESULTS

In Study-1, 4 mg/kg or greater IMP301 with FUS groups showed lower tumor growth rates of 14 ± 4 mm3/day (mean ± standard deviation) or less, compared to the control, gemcitabine, and Doxil with FUS groups with rates exceeding 28 ± 5 (p < 0.050). The addition of FUS in Study-2 decreased the tumor growth rate in the IMP301-treated groups from 36 ± 17 to 9 ± 6, which was lower than the control, FUS only, gemcitabine, and Doxil with FUS groups (p < 0.050).

CONCLUSIONS

IMP301 combined with FUS exhibited higher tumor growth suppression compared to the use of a conventional drug alone or the combination with FUS. The present study showed the potential of IMP301 to enhance the synergistic effect with FUS for the treatment of pancreatic cancer.

RELEVANCE STATEMENT

This article aims to evaluate the synergistic effect of FUS and ultrasound-responsive liposomal drug in tumor growth suppression by using xenograft mouse model of pancreatic ductal adenocarcinoma. FUS-induced ultrasound-sensitive drug release may be a potential noninvasive repeatable treatment option for patients with locally advanced or unresectable pancreatic cancer.

KEY POINTS

• Modification of conventional drugs combined with FUS would maximize tumor suppression. • IMP301 with FUS had higher tumor suppression effect compared to conventional chemotherapy. • This image-guided drug delivery would enhance therapeutic effects of systemic chemotherapy.

Ultrasound combined with microbubble mediated immunotherapy for tumor microenvironment

The tumor microenvironment (TME) plays an important role in dynamically regulating the progress of cancer and influencing the therapeutic results. Targeting the tumor microenvironment is a promising cancer treatment method in recent years. The importance of tumor immune microenvironment regulation by ultrasound combined with microbubbles is now widely recognized. Ultrasound and microbubbles work together to induce antigen release of tumor cell through mechanical or thermal effects, promoting antigen presentation and T cells' recognition and killing of tumor cells, and improve tumor immunosuppression microenvironment, which will be a breakthrough in improving traditional treatment problems such as immune checkpoint blocking (ICB) and himeric antigen receptor (CAR)-T cell therapy. In order to improve the therapeutic effect and immune regulation of TME targeted tumor therapy, it is necessary to develop and optimize the application system of microbubble ultrasound for organs or diseases. Therefore, the combination of ultrasound and microbubbles in the field of TME will continue to focus on developing more effective strategies to regulate the immunosuppression mechanisms, so as to activate anti-tumor immunity and/or improve the efficacy of immune-targeted drugs, At present, the potential value of ultrasound combined with microbubbles in TME targeted therapy tumor microenvironment targeted therapy has great potential, which has been confirmed in the experimental research and application of breast cancer, colon cancer, pancreatic cancer and prostate cancer, which provides a new alternative idea for clinical tumor treatment. This article reviews the research progress of ultrasound combined with microbubbles in the treatment of tumors and their application in the tumor microenvironment.

Effective Combination of Targeted Therapies with Sonodynamic Treatment for Use in Exploring Differences in Therapeutic Efficacy across Organelle Targets

Acoustic kinetic therapy systems that target specific organelles can improve the precision of a sonosensitizer, which is a perfect combination of targeted therapy and sonodynamic therapy (SDT) and plays an important role in current acoustic kinetic therapy. In this study, we loaded PpIX, a sonosensitizer, on targeted-functional carbon dots (CDs) via an amide reaction and then generated the mitochondria-targeted system (Mit-CDs-PpIX) and nucleus-targeted system (Nuc-CDs-PpIX), respectively, to deliver the sonosensitizer. Both systems exhibited minimal cytotoxicity in the absence of ultrasound stimulation. The efficacy of the targeted SDT systems was investigated using methylthiazol tetrazolium (MTT) assays, live/dead staining, flow cytometry, etc. Compared with the free PpIX and mitochondria-targeted system, the nucleus-targeted system is more potent in killing effect under ultrasound stimulation and induces apoptosis with higher intensity. To achieve the equal killing effect, the effective concentration of Nuc-CDs-PpIX is just one third of that of Mit-CDs-PpIX.

Nanomaterials augmented bioeffects of ultrasound in cancer immunotherapy

Immunotherapy as a milestone in cancer treatment has made great strides in the past decade, but it is still limited by low immune response rates and immune-related adverse events. Utilizing bioeffects of ultrasound to enhance tumor immunotherapy has attracted more and more attention, including sonothermal, sonomechanical, sonodynamic and sonopiezoelectric immunotherapy. Moreover, the emergence of nanomaterials has further improved the efficacy of ultrasound mediated immunotherapy. However, most of the summaries in this field are about a single aspect of the biological effects of ultrasound, which is not comprehensive and complete currently. This review proposes the recent progress of nanomaterials augmented bioeffects of ultrasound in cancer immunotherapy. The concept of immunotherapy and the application of bioeffects of ultrasound in cancer immunotherapy are initially introduced. Then, according to different bioeffects of ultrasound, the representative paradigms of nanomaterial augmented sono-immunotherapy are described, and their mechanisms are discussed. Finally, the challenges and application prospects of nanomaterial augmented ultrasound mediated cancer immunotherapy are discussed in depth, hoping to pave the way for cancer immunotherapy and promote the clinical translation of ultrasound mediated cancer immunotherapy through the reasonable combination of nanomaterials augmented ultrasonic bioeffects.

Knowledge-Based Design of Multifunctional Polymeric Nanoparticles

Conventional drug delivery systems (DDS) today still face several drawbacks and obstacles. High total doses of active pharmaceutical ingredients (API) are often difficult or impossible to deliver due to poor solubility of the API or undesired clearance from the body caused by strong interactions with plasma proteins. In addition, high doses lead to a high overall body burden, in particular if they cannot be delivered specifically to the target site. Therefore, modern DDS must not only be able to deliver a dose into the body, but should also overcome the hurdles mentioned above as examples. One of these promising devices are polymeric nanoparticles, which can encapsulate a wide range of APIs despite having different physicochemical properties. Most importantly, polymeric nanoparticles are tunable to obtain tailored systems for each application. This can already be achieved via the starting material, the polymer, by incorporating, e.g., functional groups. This enables the particle properties to be influenced not only specifically in terms of their interactions with APIs, but also in terms of their general properties such as size, degradability, and surface properties. In particular, the combination of size, shape, and surface modification allows polymeric nanoparticles to be used not only as a simple drug delivery device, but also to achieve targeting. This chapter discusses to what extent polymers can be designed to form defined nanoparticles and how their properties affect their performance.

Multistage Self-Assembled Nanomaterials for Cancer Immunotherapy

Advances in nanotechnology have brought innovations to cancer therapy. Nanoparticle-based anticancer drugs have achieved great success from bench to bedside. However, insufficient therapy efficacy due to various physiological barriers in the body remains a key challenge. To overcome these biological barriers and improve the therapeutic efficacy of cancers, multistage self-assembled nanomaterials with advantages of stimuli-responsiveness, programmable delivery, and immune modulations provide great opportunities. In this review, we describe the typical biological barriers for nanomedicines, discuss the recent achievements of multistage self-assembled nanomaterials for stimuli-responsive drug delivery, highlighting the programmable delivery nanomaterials, in situ transformable self-assembled nanomaterials, and immune-reprogramming nanomaterials. Ultimately, we perspective the future opportunities and challenges of multistage self-assembled nanomaterials for cancer immunotherapy.

Mesoporous Silica Nanoparticles: Types, Synthesis, Role in the Treatment of Alzheimer's Disease, and Other Applications

Globally, many individuals struggle with Alzheimer's disease (AD), an unrelenting and incapacitating neurodegenerative condition. Despite notable research endeavors, effective remedies for AD remain constrained, prompting the exploration of innovative therapeutic avenues. Within this context, silica-based nanoplatforms have emerged with pronounced potential due to their unique attributes like expansive surface area, customizable pore dimensions, and compatibility with living systems. These nanoplatforms hold promise as prospective interventions for AD. This assessment provides a comprehensive overview encompassing various forms of mesoporous silica nanoparticles (MSNs), techniques for formulation, and their applications in biomedicine. A significant feature lies in their ability to precisely guide and control the transport of therapeutic agents to the brain, facilitated by the adaptability of these nanoplatforms as drug carriers. Their utility as tools for early detection and monitoring of AD is investigated. Challenges and prospects associated with harnessing MSNs are studied, underscoring the imperative of stringent safety evaluations and optimization of how they interact with the body. Additionally, the incorporation of multifunctional attributes like imaging and targeting components is emphasized to enhance their efficacy within the intricate milieu of AD. As the battle against the profound repercussions of AD persists, MSNs emerge as a promising avenue with the potential to propel the development of viable therapeutic interventions.

Current research trends of nanomedicines

Owing to the inherent shortcomings of traditional therapeutic drugs in terms of inadequate therapeutic efficacy and toxicity in clinical treatment, nanomedicine designs have received widespread attention with significantly improved efficacy and reduced non-target side effects. Nanomedicines hold tremendous theranostic potential for treating, monitoring, diagnosing, and controlling various diseases and are attracting an unfathomable amount of input of research resources. Against the backdrop of an exponentially growing number of publications, it is imperative to help the audience get a panorama image of the research activities in the field of nanomedicines. Herein, this review elaborates on the development trends of nanomedicines, emerging nanocarriers, in vivo fate and safety of nanomedicines, and their extensive applications. Moreover, the potential challenges and the obstacles hindering the clinical translation of nanomedicines are also discussed. The elaboration on various aspects of the research trends of nanomedicines may help enlighten the readers and set the route for future endeavors.

Dopamine-Conjugated Bovine Serum Albumin Nanoparticles Containing pH-Responsive Catechol-V(III) Coordination for In Vitro and In Vivo Drug Delivery

V(III) instead of commonly used Fe(III) provided a rich tris-catechol-metal coordination at pH 7.4, which is important for slow drug release at physiological pH. Bovine serum albumin (BSA) functionalized with catechol-containing dopamine (D) and cross-linked using tris-catechol-V(III) coordination yielded pH-responsive compact D-BSA NPs (253 nm). However, conversion to bis- and/or mono-catechol-V(III) complexes in an acidic medium resulted in degradation of NPs and rapid release of doxorubicin (DOX). It was shown that D-BSA NPs entered cancerous MCF-7 cells (66%) more efficiently than non-cancerous HEK293T (33%) in 3 h. Also, DOX-loaded NPs reduced cell viability of MCF-7 by 75% and induced apoptosis in a majority of cells after 24 h. Biodegradability and lack of hemolytic activity were shown in vitro, whereas a lack of toxicity was shown in histological sections of zebrafish. Furthermore, 30% of circulating tumor cells in vasculature in 24 h were killed by DOX-loaded NPs shown with the zebrafish CTC xenograft model.

Application of low-intensity ultrasound by opening blood-brain barrier for enhanced brain-targeted drug delivery

Brain-targeted drug delivery has been a research hotspot, and substantial amount of related studies were already translated into standard therapy and put into clinical use. However, low effective rate retains a huge challenge for brain disease. Because, the blood-brain barrier (BBB) protects brain from pathogenic molecules and tightly controls the process of molecular transportation, which gives rise to poor-liposoluble drugs or molecules with high molecular weight cannot permeate the barrier to exert treating effect. There is an ongoing process to dig out more methods for efficient brain-targeted drug delivery. Besides modified chemical methods such as prodrugs design and brain-targeted nanotechnology, physical methods as a novel initiative could enhance the treatment effect for brain disease. In our study, the influence of low-intensity ultrasound on transient opening BBB and the related applications were explored. A medical ultrasound therapeutic device (1 MHz) was used on heads of mice at different intensities and for different treating time. Evans blue was used as a model to exhibit the permeability of the BBB after subcutaneous injection. Three types of intensities (0.6, 0.8, and 1.0 W/cm2) and duration times (1, 3, and 5 min) of ultrasound were respectively investigated. It was found that the combinations of 0.6 W/cm2/1 min, 0.6 W/cm2/3 min, 0.6 W/cm2/5 min, 0.8 W/cm2/1 min, and 1.0 W/cm2/1 min could open the BBB sufficiently with significant Evans blue staining in the brain. Brain pathological analysis showed structural change on moderate degree was found on cerebral cortex after ultrasound and could recovered rapidly. There are no obvious changes in the behavior of mice after ultrasound processing. More importantly, the BBB recovered quickly at 12 h after ultrasound application with complete BBB structure and unbroken tight junction, suggesting that ultrasound was safe to apply for brain-targeted drug delivery. Proper use of local ultrasound on the brain is a promising technique to open the BBB and enhance brain-targeted delivery.

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

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

Focused ultrasound for treatment of peripheral brain tumors

Malignant brain tumors are the leading cause of cancer-related death in children and remain a significant cause of morbidity and mortality throughout all demographics. Central nervous system (CNS) tumors are classically treated with surgical resection and radiotherapy in addition to adjuvant chemotherapy. However, the therapeutic efficacy of chemotherapeutic agents is limited due to the blood-brain barrier (BBB). Magnetic resonance guided focused ultrasound (MRgFUS) is a new and promising intervention for CNS tumors, which has shown success in preclinical trials. High-intensity focused ultrasound (HIFU) has the capacity to serve as a direct therapeutic agent in the form of thermoablation and mechanical destruction of the tumor. Low-intensity focused ultrasound (LIFU) has been shown to disrupt the BBB and enhance the uptake of therapeutic agents in the brain and CNS. The authors present a review of MRgFUS in the treatment of CNS tumors. This treatment method has shown promising results in preclinical trials including minimal adverse effects, increased infiltration of the therapeutic agents into the CNS, decreased tumor progression, and improved survival rates.

Sonoprinting nanoparticles on cellular spheroids via surface acoustic waves for enhanced nanotherapeutics delivery

Nanotherapeutics, on their path to the target tissues, face numerous physicochemical hindrances that affect their therapeutic efficacy. Physical barriers become more pronounced in pathological tissues, such as solid tumors, where they limit the penetration of nanocarriers into deeper regions, thereby preventing the efficient delivery of drug cargo. To address this challenge, we introduce a novel approach that employs surface acoustic wave (SAW) technology to sonoprint and enhance the delivery of nanoparticles onto and into cell spheroids. Our SAW platform is designed to generate focused and unidirectional acoustic waves for creating vigorous acoustic streaming while promoting Bjerknes forces. The effect of SAW excitation on cell viability, as well as the accumulation and penetration of nanoparticles on human breast cancer (MCF 7) and mouse melanoma (YUMM 1.7) cell spheroids were investigated. The high frequency, low input voltage, and contact-free nature of the proposed SAW system ensured over 92% cell viability for both cell lines after SAW exposure. SAW sonoprinting enhanced the accumulation of 100 nm polystyrene particles on the periphery of the spheroids to near four-fold, while the penetration of nanoparticles into the core regions of the spheroids was improved up to three times. To demonstrate the effectiveness of our SAW platform on the efficacy of nanotherapeutics, the platform was used to deliver nanoliposomes encapsulated with the anti-cancer metal compound copper diethyldithiocarbamate (CuET) to MCF 7 and YUMM 1.7 cell spheroids. A three-fold increase in the cytotoxic activity of the drug was observed in spheroids under the effect of SAW, compared to controls. The capacity of SAW-based devices to be manufactured as minuscule wearable patches can offer highly controllable, localized, and continuous acoustic waves to enhance drug delivery efficiency to target tissues.

Current Trends in Nanotheranostics: A Concise Review on Bioimaging and Smart Wearable Technology

The area of interventional nanotheranostics combines the use of interventional procedures with nanotechnology for the detection and treatment of physiological disorders. Using catheters or endoscopes, for example, interventional techniques make use of minimally invasive approaches to diagnose and treat medical disorders. It is feasible to increase the precision of these approaches and potency by integrating nanotechnology. To visualize and target various parts of the body, such as tumors or obstructed blood veins, one can utilize nanoscale probes or therapeutic delivery systems. Interventional nanotheranostics offers targeted, minimally invasive therapies that can reduce side effects and enhance patient outcomes, and it has the potential to alter the way that many medical illnesses are handled. Clinical enrollment and implementation of such laboratory scale theranostics approach in medical practice is promising for the patients where the user can benefit by tracking its physiological state. This review aims to introduce the most recent advancements in the field of clinical imaging and diagnostic techniques as well as newly developed on-body wearable devices to deliver therapeutics and monitor its due alleviation in the biological milieu.

Tumor Spheroids as Model to Design Acoustically Mediated Drug Therapies: A Review

Tumor spheroids as well as multicellular tumor spheroids (MCTSs) are promising 3D in vitro tumor models for drug screening, drug design, drug targeting, drug toxicity, and validation of drug delivery methods. These models partly reflect the tridimensional architecture of tumors, their heterogeneity and their microenvironment, which can alter the intratumoral biodistribution, pharmacokinetics, and pharmacodynamics of drugs. The present review first focuses on current spheroid formation methods and then on in vitro investigations exploiting spheroids and MCTS for designing and validating acoustically mediated drug therapies. We discuss the limitations of the current studies and future perspectives. Various spheroid formation methods enable the easy and reproducible generation of spheroids and MCTSs. The development and assessment of acoustically mediated drug therapies have been mainly demonstrated in spheroids made up of tumor cells only. Despite the promising results obtained with these spheroids, the successful evaluation of these therapies will need to be addressed in more relevant 3D vascular MCTS models using MCTS-on-chip platforms. These MTCSs will be generated from patient-derived cancer cells and nontumor cells, such as fibroblasts, adipocytes, and immune cells.

Ultrasound-mediated nano drug delivery for treating cancer: Fundamental physics to future directions

The application of biocompatible nanocarriers in medicine has provided several benefits over conventional treatment methods. However, achieving high treatment efficacy and deep penetration of nanocarriers in tumor tissue is still challenging. To address this, stimuli-responsive nano-sized drug delivery systems (DDSs) are an active area of investigation in delivering anticancer drugs. While ultrasound is mainly used for diagnostic purposes, it can also be applied to affect cellular function and the delivery/release of anticancer drugs. Therapeutic ultrasound (TUS) has shown potential as both a stand-alone anticancer treatment and a method to induce targeted drug release from nanocarrier systems. TUS approaches have been used to overcome various physiological obstacles, including endothelial barriers, the tumor microenvironment (TME), and immunological hurdles. Combining nanomedicine and ultrasound as a smart DDS can increase in situ drug delivery and improve access to impermeable tissues. Furthermore, smart DDSs can perform targeted drug release in response to distinctive TMEs, external triggers, or dual/multi-stimulus. This results in enhanced treatment efficacy and reduced damage to surrounding healthy tissue or organs at risk. Integrating DDSs and ultrasound is still in its early stages. More research and clinical trials are required to fully understand ultrasound's underlying physical mechanisms and interactions with various types of nanocarriers and different types of cells and tissues. In the present review, ultrasound-mediated nano-sized DDS, specifically focused on cancer treatment, is presented and discussed. Ultrasound interaction with nanoparticles (NPs), drug release mechanisms, and various types of ultrasound-sensitive NPs are examined. Additionally, in vitro, in vivo, and clinical applications of TUS are reviewed in light of the critical challenges that need to be considered to advance TUS toward an efficient, secure, straightforward, and accessible cancer treatment. This study also presents effective TUS parameters and safety considerations for this treatment modality and gives recommendations about system design and operation. Finally, future perspectives are considered, and different TUS approaches are examined and discussed in detail. This review investigates drug release and delivery through ultrasound-mediated nano-sized cancer treatment, both pre-clinically and clinically.

The State of the Art of Natural Polymer Functionalized Fe3O4 Magnetic Nanoparticle Composites for Drug Delivery Applications: A Review

Natural polymers have received a great deal of interest for their potential use in the encapsulation and transportation of pharmaceuticals and other bioactive compounds for disease treatment. In this perspective, the drug delivery systems (DDS) constructed by representative natural polymers from animals (gelatin and hyaluronic acid), plants (pectin and starch), and microbes (Xanthan gum and Dextran) are provided. In order to enhance the efficiency of polymers in DDS by delivering the medicine to the right location, reducing the medication's adverse effects on neighboring organs or tissues, and controlling the medication's release to stop the cycle of over- and under-dosing, the incorporation of Fe3O4 magnetic nanoparticles with the polymers has engaged the most consideration due to their rare characteristics, such as easy separation, superparamagnetism, and high surface area. This review is designed to report the recent progress of natural polymeric Fe3O4 magnetic nanoparticles in drug delivery applications, based on different polymers' origins.

Exosomes and ultrasound: The future of theranostic applications

Biomaterials and pertaining formulations have been very successful in various diagnostic and therapeutic applications because of its ability to overcome pharmacological limitations. Some of them have gained significant focus in the recent decade for their theranostic properties. Exosomes can be grouped as biomaterials, since they consist of various biological micro/macromolecules and possess all the properties of a stable biomaterial with size in nano range. Significant research has gone into isolation and exploitation of exosomes as potential theranostic agent. However, the limitations in terms of yield, efficacy, and target specificity are continuously being addressed. On the other hand, several nano/microformulations are responsive to physical or chemical alterations and were successfully stimulated by tweaking the physical characteristics of the surrounding environment they are in. Some of them are termed as photodynamic, sonodynamic or thermodynamic therapeutic systems. In this regard, ultrasound and acoustic systems were extensively studied for its ability towards altering the properties of the systems to which they were applied on. In this review, we have detailed about the diagnostic and therapeutic applications of exosomes and ultrasound separately, consisting of their conventional applications, drawbacks, and developments for addressing the challenges. The information were categorized into various sections that provide complete overview of the isolation strategies and theranostic applications of exosomes in various diseases. Then the ultrasound-based disease diagnosis and therapy were elaborated, with special interest towards the use of ultrasound in enhancing the efficacy of nanomedicines and nanodrug delivery systems, Finally, we discussed about the ability of ultrasound in enhancing the diagnostic and therapeutic properties of exosomes, which could be the future of theranostics.

Use of stimulatory responsive soft nanoparticles for intracellular drug delivery

Drug delivery has made tremendous advances in the last decade. Targeted therapies are increasingly common, with intracellular delivery highly impactful and sought after. Intracellular drug delivery systems have limitations due to imprecise and non-targeted release profiles. One way this can be addressed is through using stimuli-responsive soft nanoparticles, which contain materials with an organic backbone such as lipids and polymers. The choice of biomaterial is essential for soft nanoparticles to be responsive to internal or external stimuli. The nanoparticle must retain its integrity and payload in non-targeted physiological conditions while responding to particular intracellular environments where payload release is desired. Multiple internal and external factors could stimulate the intracellular release of drugs from nanoparticles. Internal stimuli include pH, oxidation, and enzymes, while external stimuli include ultrasound, light, electricity, and magnetic fields. Stimulatory responsive soft nanoparticulate systems specifically utilized to modulate intracellular delivery of drugs are explored in this review.

NIR-triggered ligand-presenting nanocarriers for enhancing synergistic photothermal-chemotherapy

Surface PEGylation of nanomedicine is effective for prolonging blood circulation time and facilitating the EPR effect, whereas the hydrophilic stealth surface inhibits effective cellular uptake and hinders active targeting. To address the dilemma, herein, a NIR light-triggered dePEGylation/ligand-presenting strategy based on thermal decomposition of azo bonds is developed, whereby Dox/Pz-IR nanoparticle is self-assembled from thermo-labile azo molecule-linked long PEG chain polymer (Pz-IR), cRGD-conjugated IR783 with short PEG chains (rP-IR) and doxorubicin. The long PEG chains could mask cRGD peptides in the blood circulation, preventing serum degradation and nonspecific interaction with normal cells. Once exposed to NIR laser, the PEG corona is stripped off owing to the rupture of azo bonds through the photothermal effect of IR783, and the masked cRGD peptides are exposed, which remarkably enhances cellular uptake by tumor cells and improves tumor accumulation. Dox/Pz-IR achieves the optimal synergy of photothermal-chemotherapy at mild temperature through progressive tumor accumulation, precisely regulated photothermal effect and NIR-PTT induced pulsated drug release. The strategy of NIR photo-driven dePEGylation/targeting offers a new approach to overcoming the "PEG dilemma", and provides a noval avenue for programmed tumor-targeted drug delivery.

Establishment of ultrasound-responsive SonoBacteriaBot for targeted drug delivery and controlled release

Bacteria-driven biohybrid microbots have shown great potential in caⁿcer treatment. However, how precisely controlling drug release at the tumor site is still an issue. To overcome the limitation of this system, we proposed the ultrasound-responsive SonoBacteriaBot (DOX-PFP-PLGA@EcM). Doxorubicin (DOX) and perfluoro-n-pentane (PFP) were encapsulated in polylactic acid-glycolic acid (PLGA) to form ultrasound-responsive DOX-PFP-PLGA nanodroplets. Then, DOX-PFP-PLGA@EcM is created by DOX-PFP-PLGA amide-bonded to the surface of E. coli MG1655 (EcM). The DOX-PFP-PLGA@EcM was proved to have the characteristics of high tumor-targeting efficiency, controlled drug release capability, and ultrasound imaging. Based on the acoustic phase change function of nanodroplets, DOX-PFP-PLGA@EcM enhance the signal of US imaging after ultrasound irradiation. Meanwhile, the DOX loaded into DOX-PFP-PLGA@EcM can be released. After being intravenously injected, DOX-PFP-PLGA@EcM can efficiently accumulate in tumors without causing harm to critical organs. In conclusion, the SonoBacteriaBot has significant benefits in real-time monitoring and controlled drug release, which has significant potential applications for therapeutic drug delivery in clinical settings.

Insights on the Dynamic Innovative Tumor Targeted-Nanoparticles-Based Drug Delivery Systems Activation Techniques

Anti-cancer conventional chemotherapeutic drugs novel formula progress, nowadays, uses nano technology for targeted drug delivery, specifically tailored to overcome therapeutic agents' delivery challenges. Polymer drug delivery systems (DDS) play a crucial role in minimizing off-target side effects arising when using standard cytotoxic drugs. Using nano-formula for targeted localized action, permits using larger effective cytotoxic doses on a single special spot, that can seriously cause harm if it was administered systemically. Therefore, various nanoparticles (NPs) specifically have attached groups for targeting capabilities, not seen in bulk materials, which then need activation. In this review, we will present a simple innovative, illustrative, in a cartoon-way, enumeration of NP anti-cancer drug targeting delivery system activation-types. Area(s) covered in this review are the mechanisms of various NP activation techniques.

Newly developed gas-assisted sonodynamic therapy in cancer treatment

Sonodynamic therapy (SDT) is an emerging noninvasive treatment modality that utilizes low-frequency and low-intensity ultrasound (US) to trigger sensitizers to kill tumor cells with reactive oxygen species (ROS). Although SDT has attracted much attention for its properties including high tumor specificity and deep tissue penetration, its anticancer efficacy is still far from satisfactory. As a result, new strategies such as gas-assisted therapy have been proposed to further promote the effectiveness of SDT. In this review, the mechanisms of SDT and gas-assisted SDT are first summarized. Then, the applications of gas-assisted SDT for cancer therapy are introduced and categorized by gas types. Next, therapeutic systems for SDT that can realize real-time imaging are further presented. Finally, the challenges and perspectives of gas-assisted SDT for future clinical applications are discussed.

Recent Advances in Stimuli-Responsive Doxorubicin Delivery Systems for Liver Cancer Therapy

Doxorubicin (DOX) is one of the most commonly used drugs in liver cancer. Unfortunately, the traditional chemotherapy with DOX presents many limitations, such as a systematic release of DOX, affecting both tumor tissue and healthy tissue, leading to the apparition of many side effects, multidrug resistance (MDR), and poor water solubility. Furthermore, drug delivery systems' responsiveness has been intensively studied according to the influence of different internal and external stimuli on the efficiency of therapeutic drugs. In this review, we discuss both internal stimuli-responsive drug-delivery systems, such as redox, pH and temperature variation, and external stimuli-responsive drug-delivery systems, such as the application of magnetic, photo-thermal, and electrical stimuli, for the controlled release of Doxorubicin in liver cancer therapy, along with the future perspectives of these smart delivery systems in liver cancer therapy.

Metal-Organic Frameworks as Intelligent Drug Nanocarriers for Cancer Therapy

Metal-organic frameworks (MOFs) are crystalline porous materials with periodic network structures formed by self-assembly of metal ions and organic ligands. Attributed to their tunable composition and pore size, ultrahigh surface area (1000-7000 m2/g) and pore volume (1.04-4.40 cm3/g), easy surface modification, appropriate physiological stability, etc., MOFs have been widely used in biomedical applications in the last two decades, especially for the delivery of bioactive agents. In the initial stage, MOFs were widely used to load small molecule drugs with ultra-high doses. Whereafter, more recent work has focused on the load of biomacromolecules, such as nucleic acids and proteins. Over the past years, we have devoted extensive effort to investigate the function of MOF materials for bioactive agent delivery. MOFs can be used not only as an intelligent nanocarrier to deliver or protect bioactive agents but also as an activator for their release or activation in response to the different microenvironments. Altogether, this review details the current progress of MOF materials for bioactive agent delivery and looks into their future development.

Ultrasonically Enhanced ZD2767P-Carboxypeptidase G2 Deactivates Cisplatin-Resistant Human Lung Cancer Cells

The prodrug-enzyme regimen ZD2767P+CPG2 is limited by low efficacy. Here, ultrasound was used to modulate ZD2767P+CPG2 (i.e., ZD2767P+CPG2+US) against cisplatin-resistant human lung cancer cells. A549 and A549/DDP (resistant subline) cells received ZD2767P+CPG2 or ZD2767P+CPG2+US. Either ZD2767P+CPG2 or ZD2767P+CPG2+US led to cell death and apoptosis, and ZD2767P+CPG2+US produced stronger effects; comet assays revealed that these two means directly caused DNA double-strand break. Z-VAD-fmk and/or ferrostatin-1 increased the cell survival percentage, and Z-VAD-fmk decreased the apoptosis percentage. The level of transferrin was increased in treated cells, but those of ferroportin and glutathione peroxidase 4 (GPX4) were reduced, with higher intracellular levels of reactive oxygen species and of iron. Intracellular pharmacokinetics of ZD2767D (activated drug) indicated that the peak level, area under the drug level vs. time curve, and mean residence time in ZD2767P+CPG2+US were higher than those in ZD2767P+CPG2. Both ZD2767P+CPG2 and ZD2767P+CPG2+US were effective on xenograft tumors in nude mice; inhibitory rates were 39.7% and 63.5% in A549 tumors and 50.0% and 70.1% in A549/DDP tumors, respectively. A higher apoptosis level and a lower GPX4 level were noted in tumors receiving treatments. No severe adverse events were observed. These data demonstrated that ZD2767P+CPG2+US deactivated cancer cells via apoptosis and ferroptosis pathways, being a candidate therapy for cisplatin-resistant lung cancer.