Hyperthermia-triggered drug delivery from iRGD-modified temperature-sensitive liposomes enhances the anti-tumor efficacy using high intensity focused ultrasound

The advancements and prospective developments in anti-tumor targeted therapy

Cancer poses a major threat to human health worldwide. The development of anti-tumor materials provides new modalities for cancer diagnosis and treatment. In this review, we comprehensively summarize the research progress and clinical applications of anti-tumor materials. First, we introduce the etiology and pathogenesis of cancer, and the significance and challenges of anti-tumor materials research. Then, we classify anti-tumor materials and discuss their mechanisms of action. After that, we elaborate the research advances and clinical applications of anti-tumor materials, including those targeting tumor cells and therapeutic instruments. Finally, we discuss the future perspectives and challenges in the field of anti-tumor materials. This review aims to provide an overview of the current status of anti-tumor materials research and application, and to offer insights into future directions in this rapidly evolving field, which holds promise for more precise, efficient and customized treatment of cancer.

Ultrasound-Based Micro-/Nanosystems for Biomedical Applications

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

Smart composite scaffold to synchronize magnetic hyperthermia and chemotherapy for efficient breast cancer therapy

Combination of different therapies is an attractive approach for cancer therapy. However, it is a challenge to synchronize different therapies for maximization of therapeutic effects. In this work, a smart composite scaffold that could synchronize magnetic hyperthermia and chemotherapy was prepared by hybridization of magnetic Fe3O4 nanoparticles and doxorubicin (Dox)-loaded thermosensitive liposomes with biodegradable polymers. Irradiation of alternating magnetic field (AMF) could not only increase the scaffold temperature for magnetic hyperthermia but also trigger the release of Dox for chemotherapy. The two functions of magnetic hyperthermia and chemotherapy were synchronized by switching AMF on and off. The synergistic anticancer effects of the composite scaffold were confirmed by in vitro cell culture and in vivo animal experiments. The composite scaffold could efficiently eliminate breast cancer cells under AMF irradiation. Moreover, the scaffold could support proliferation and adipogenic differentiation of mesenchymal stem cells for adipose tissue reconstruction after anticancer treatment. In vivo regeneration experiments showed that the composite scaffolds could effectively maintain their structural integrity and facilitate the infiltration and proliferation of normal cells within the scaffolds. The composite scaffold possesses multi-functions and is attractive as a novel platform for efficient breast cancer therapy.

Peptide-Mediated Nanocarriers for Targeted Drug Delivery: Developments and Strategies

Effective drug delivery is essential for cancer treatment. Drug delivery systems, which can be tailored to targeted transport and integrated tumor therapy, are vital in improving the efficiency of cancer treatment. Peptides play a significant role in various biological and physiological functions and offer high design flexibility, excellent biocompatibility, adjustable morphology, and biodegradability, making them promising candidates for drug delivery. This paper reviews peptide-mediated drug delivery systems, focusing on self-assembled peptides and peptide-drug conjugates. It discusses the mechanisms and structural control of self-assembled peptides, the varieties and roles of peptide-drug conjugates, and strategies to augment peptide stability. The review concludes by addressing challenges and future directions.

Ultrasound-nanovesicles interplay for theranostics

Nanovesicles (NVs) are widely used in the treatment and diagnosis of diseases due to their excellent vascular permeability, good biocompatibility, high loading capacity, and easy functionalization. However, their yield and in vivo penetration depth limitations and their complex preparation processes still constrain their application and development. Ultrasound, as a fundamental external stimulus with deep tissue penetration, concentrated energy sources, and good safety, has been proven to be a patient-friendly and highly efficient strategy to overcome the restrictions of traditional clinical medicine. Recent research has shown that ultrasound can drive the generation of NVs, increase their yield, simplify their preparation process, and provide direct therapeutic effects and intelligent control to enhance the therapeutic effect of NVs. In addition, NVs, as excellent drug carriers, can enhance the targeting efficiency of ultrasound-based sonodynamic therapy or sonogenetic regulation and improve the accuracy of ultrasound imaging. This review provides a detailed introduction to the classification, generation, and modification strategies of NVs, emphasizing the impact of ultrasound on the formation of NVs and summarizing the enhanced treatment and diagnostic effects of NVs combined with ultrasound for various diseases.

Light-activatable and hyperthermia-sensitive "all-in-one" theranostics: NIR-II fluorescence imaging and chemo-photothermal therapy of subcutaneous glioblastoma by temperature-sensitive liposome-containing AIEgens and paclitaxel

Nowadays, it is still quite difficult to combat glioblastoma, which is one of the most lethal cancers for human beings. Combinatory therapy, which could not only improve therapeutic efficacy and overcome multiple drug resistance but also decrease the threshold therapeutic drug dosage and minimize side effects, would be an appealing candidate for glioblastoma treatment. Herein, we report fluorescence imaging in the second near-infrared window (NIR-II)-guided combinatory photothermal therapy (PTT) and chemotherapy of glioblastoma with a newly formulated nanomedicine termed PATSL. It is composed of temperature-sensitive liposome (TSL) carriers, NIR-II emissive and photothermal aggregation-induced emission (AIE) dyes, and chemotherapeutic paclitaxel (PTX) as well. PATSL shows spherical morphology with diameters of approximately 55 and 85 nm by transmission electron microscopy and laser light scattering, respectively, a zeta potential of -14.83 mV, good stability in both size and photoactivity, strong light absorption with a peak of approximately 770 nm, and bright emission from 900 nm to 1,200 nm. After excitation with an 808-nm laser with good spatiotemporal controllability, PATSL emits bright NIR-II fluorescence signals for tumor diagnosis in vivo, exhibits high photothermal conversion efficiency (68.8%), and triggers drug release of PTX under hypothermia, which assists in efficient tumor ablation in vitro and in vivo. This research demonstrates that "all-in-one" theranostics with NIR-II fluorescence imaging-guided combinatory PTT and chemotherapy is an efficient treatment paradigm for improving the prognosis of brain cancers.

Nanoparticle-Mediated Hyperthermia and Cytotoxicity Mechanisms in Cancer

Hyperthermia has the potential to damage cancerous tissue by increasing the body temperature. However, targeting cancer cells whilst protecting the surrounding tissues is often challenging, especially when implemented in clinical practice. In this direction, there are data showing that the combination of nanotechnology and hyperthermia offers more successful penetration of nanoparticles in the tumor environment, thus allowing targeted hyperthermia in the region of interest. At the same time, unlike radiotherapy, the use of non-ionizing radiation makes hyperthermia an attractive therapeutic option. This review summarizes the existing literature regarding the use of hyperthermia and nanoparticles in cancer, with a focus on nanoparticle-induced cytotoxicity mechanisms.

Cancer therapy with iRGD as a tumor-penetrating peptide

One of the primary threats in tumor treatment revolves around the limited ability to penetrate tumor sites, leading to reduced therapeutic effectiveness, which remains a critical concern. Recently gaining importance are novel peptides, namely CRGDK/RGPD/EC (iRGD), that possess enhanced tumor-penetrating and inhibitory properties. These peptides specifically target and penetrate tumors by binding to αvβ integrins, namely αvβ3 and αvβ5, as well as NRP-1 receptors. Remarkably abundant on both the vasculature and tumor cell surfaces, these peptides show promising potential for improving tumor treatment outcomes. As a result, iRGD penetrated deep into the tumor tissues with biological products, contrast agents (imaging agents), antitumor drugs, and immune modulators after co-injecting them with peptides or chemically linked to peptides. The synthesis of iRGD peptides is a relatively straightforward process compared to the synthesis of other traditional peptides, and they significantly improved tumor tissue penetration inhibiting tumor metastasis effectively. Recent studies demonstrate the effectiveness of iRGD-driven dual-targeting chemotherapeutics on cancer cells, and the nanocarriers were modified with iRGD, serving as a favorable delivery strategy of payloads for deeper tumor regions. This review aims to provide an overview to emphasize the recent advancements and advantages of iRGD in treating and imaging various cancers.

Cell penetrating peptides: Highlighting points in cancer therapy

Cell-penetrating peptides (CPPs), first identified in HIV a few decades ago, deserved great attention in the last two decades; especially to support the penetration of anticancer drug means. In the drug delivery discipline, they have been involved in various approaches from mixing with hydrophobic drugs to the use of genetically conjugated proteins. The early classification as cationic and amphipathic CPPs has been extended to a few more classes such as hydrophobic and cyclic CPPs so far. Developing potential sequences utilized almost all methods of modern science: choosing high-efficiency peptides from natural protein sequences, sequence-based comparison, amino acid substitution, obtaining chemical and/or genetic conjugations, in silico approaches, in vitro analysis, animal experiments, etc. The bottleneck effect in this discipline reveals the complications that modern science faces in drug delivery research. Most CPP-based drug delivery systems (DDSs) efficiently inhibited tumor volume and weight in mice, but only in rare cases reduced their levels and continued further processes. The integration of chemical synthesis into the development of CPPs made a significant contribution and even reached the clinical stage as a diagnostic tool. But constrained efforts still face serious problems in overcoming biobarriers to reach further achievements. In this work, we reviewed the roles of CPPs in anticancer drug delivery, focusing on their amino acid composition and sequences. As the most suitable point, we relied on significant changes in tumor volume in mice resulting from CPPs. We provide a review of individual CPPs and/or their derivatives in a separate subsection.

Ultrasound-Mediated Ocular Drug Delivery: From Physics and Instrumentation to Future Directions

Drug delivery to the anterior and posterior segments of the eye is impeded by anatomical and physiological barriers. Increasingly, the bioeffects produced by ultrasound are being proven effective for mitigating the impact of these barriers on ocular drug delivery, though there does not appear to be a consensus on the most appropriate system configuration and operating parameters for this application. In this review, the fundamental aspects of ultrasound physics most pertinent to drug delivery are presented; the primary phenomena responsible for increased drug delivery efficacy under ultrasound sonication are discussed; an overview of common ocular drug administration routes and the associated ocular barriers is also given before reviewing the current state of the art of ultrasound-mediated ocular drug delivery and its potential future directions.

Recent Preclinical and Clinical Progress in Liposomal Doxorubicin

Doxorubicin (DOX) is a potent anti-cancer agent that has garnered great interest in research due to its high efficacy despite dose-limiting toxicities. Several strategies have been exploited to enhance the efficacy and safety profile of DOX. Liposomes are the most established approach. Despite the improvement in safety properties of liposomal encapsulated DOX (in Doxil and Myocet), the efficacy is not superior to conventional DOX. Functionalized (targeted) liposomes present a more effective system to deliver DOX to the tumor. Moreover, encapsulation of DOX in pH-sensitive liposomes (PSLs) or thermo-sensitive liposomes (TSLs) combined with local heating has improved DOX accumulation in the tumor. Lyso-thermosensitive liposomal DOX (LTLD), MM-302, and C225-immunoliposomal(IL)-DOX have reached clinical trials. Further functionalized PEGylated liposomal DOX (PLD), TSLs, and PSLs have been developed and evaluated in preclinical models. Most of these formulations improved the anti-tumor activity compared to the currently available liposomal DOX. However, the fast clearance, the optimization of ligand density, stability, and release rate need more investigations. Therefore, we reviewed the latest approaches applied to deliver DOX more efficiently to the tumor, preserving the benefits obtained from FDA-approved liposomes.

Enhancing the therapeutic efficacy of nanoparticles for cancer treatment using versatile targeted strategies

Poor targeting of therapeutics leading to severe adverse effects on normal tissues is considered one of the obstacles in cancer therapy. To help overcome this, nanoscale drug delivery systems have provided an alternative avenue for improving the therapeutic potential of various agents and bioactive molecules through the enhanced permeability and retention (EPR) effect. Nanosystems with cancer-targeted ligands can achieve effective delivery to the tumor cells utilizing cell surface-specific receptors, the tumor vasculature and antigens with high accuracy and affinity. Additionally, stimuli-responsive nanoplatforms have also been considered as a promising and effective targeting strategy against tumors, as these nanoplatforms maintain their stealth feature under normal conditions, but upon homing in on cancerous lesions or their microenvironment, are responsive and release their cargoes. In this review, we comprehensively summarize the field of active targeting drug delivery systems and a number of stimuli-responsive release studies in the context of emerging nanoplatform development, and also discuss how this knowledge can contribute to further improvements in clinical practice.

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

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

Nanomaterials in cancer: Reviewing the combination of hyperthermia and triggered chemotherapy

Nanoparticle mediated hyperthermia has been explored as a method to increase cancer treatment efficacy by heating tumours inside-out. With that purpose, nanoparticles have been designed and their properties tailored to respond to external stimuli and convert the supplied energy into heat, therefore inducing damage to tumour cells. Moreover, the combination of hyperthermia with chemotherapy has been described as a more effective strategy due to the synergy between the high temperature and the drug's effects, also associated with a remote controlled and on-demand drug release. In this review, the methods behind nanoparticle mediated hyperthermia, namely material design, external stimuli response and energy conversion will be discussed and critically analysed. We will address the most relevant studies on hyperthermia and temperature triggered drug release for cancer treatment. Finally, the advantages, difficulties and challenges of this therapeutic strategy will be discussed, while giving insight for future developments.

Synthetic cells in biomedical applications

Synthetic cells are engineered vesicles that can mimic one or more salient features of life. These features include directed localization, sense-and-respond behavior, gene expression, metabolism, and high stability. In nanomedicine, many of these features are desirable capabilities of drug delivery vehicles but are difficult to engineer. In this focus article, we discuss where synthetic cells offer unique advantages over nanoparticle and living cell therapies. We review progress in the engineering of the above life-like behaviors and how they are deployed in nanomedicine. Finally, we assess key challenges synthetic cells face before being deployed as drugs and suggest ways to overcome these challenges. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Biology-Inspired Nanomaterials > Lipid-Based Structures.

Tumor microenvironment and nanotherapeutics: intruding the tumor fort

Over recent years, advancements in nanomedicine have allowed new approaches to diagnose and treat tumors. Nano drug delivery systems exploit the enhanced permeability and retention (EPR) effect and enter the tumor tissue's interstitial space. However, tumor barriers play a crucial role, and cause inefficient EPR or the homing effect. Mounting evidence supports the hypothesis that the components of the tumor microenvironment, such as the extracellular matrix, and cellular and physiological components collectively or cooperatively hinder entry and distribution of drugs, and therefore, limit the theragnostic applications of cancer nanomedicine. This abnormal tumor microenvironment plays a pivotal role in cancer nanomedicine and was recently recognized as a promising target for improving nano-drug delivery and their therapeutic outcomes. Strategies like passive or active targeting, stimuli-triggered nanocarriers, and the modulation of immune components have shown promising results in achieving anticancer efficacy. The present review focuses on the tumor microenvironment and nanoparticle-based strategies (polymeric, inorganic and organic nanoparticles) for intruding the tumor barrier and improving therapeutic effects.

Versatile Nanodrugs Containing Glutathione and Heme Oxygenase 1 Inhibitors Enable Suppression of Antioxidant Defense System in a Two-Pronged Manner for Enhanced Photodynamic Therapy

The antioxidant defense system in malignant cells, which involves antioxidant enzymes and antioxidant molecules, is an innate barrier to photodynamic therapy (PDT). Because of the complexity of the endogenous antioxidant mechanisms of these cells, simply inhibiting individual antioxidant pathways has a limited effect on improving the lethality of ROS. To enhance the efficacy of PDT for tumor treatment, a versatile nanoparticle (NP)-based drug is developed, which the authors call PZB NP, containing the glutathione inhibitor l-buthionine sulfoximine (BSO) and the heme oxygenase 1 (HO-1) inhibitor protoporphyrin zinc(II) (ZnPP) to suppress the innate antioxidant defense system of cancer cells in a two-pronged manner. BSO reduces intracellular glutathione levels to minimize ROS elimination and protein protection during PDT, and ZnPP inhibits the ROS-stimulated upregulation of the antioxidant HO-1, thus preventing ROS removal by cells after PDT. Thus, BSO and ZnPP synergistically suppress the antioxidant defense systems of cancer cells both during and after protoporphyrin-IX-mediated PDT in a two-pronged manner, resulting in tumor cell death through excess oxidative pressure. The results demonstrate that the construction of nanodrugs having dual antioxidation defense suppression properties is a promising route for the development of highly efficient ROS-based therapies.

Liposomes-based nanoplatform enlarges ultrasound-related diagnostic and therapeutic precision

Ultrasound (US) is notable in the medical field as a safe and effective imaging modality due to its lack of ionizing radiation, non-invasive approach, and real-time monitoring capability. Accompanying recent progress in nanomedicine, US has been providing hope of theranostic capability not only for imaging-based diagnosis but also for US-based therapy by taking advantage of the bioeffects induced by US. Cavitation, sonoporation, thermal effects, and other cascade effects stimulated by acoustic energy conversion have contributed to medical problem-solving in the past decades although to varying degrees of efficacy in comparisons to other methods. Recently, the usage of liposomes-based nanoplatform fuels the development of nanomedicine and provides novel clinical strategies for antitumor, thrombolysis, and controlled drug release. Merging of novel liposome-based nanoplatforms and US-induced reactions has promise for a new blueprint for future medicine. In the present review article, the value of liposome-based nanoplatforms in US-related diagnosis and therapy will be discussed and summarized along with potential future directions for further investigations.

Rapid preparation of nanogels by photopolymerization at 532 nm

The strategy of laser beam expansion was used to rapidly prepare nanogels by photopolymerization at 532 nm under low monomer concentration. According to the unique micellar morphology formed by amphiphilic polyethylene glycol diacrylate (PEGDA) in water, the monomer concentration was largely decreased to increase the distance of micellar aggregates. In this case, the photo-crosslinking could prefer to occur inside the micelles instead of crosslinking between the micellar aggregates. The variations of double bond content with reaction time in different beam expansion experiments were investigated. Finally, nanogels with uniform size could be rapidly prepared by regulating the reaction parameters, including monomer concentration, reaction time and power density.

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

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

Dual-Targeting and Stimuli-Triggered Liposomal Drug Delivery in Cancer Treatment

The delivery of chemotherapeutics to solid tumors using smart drug delivery systems (SDDSs) takes advantage of the unique physiology of tumors (i.e., disordered structure, leaky vasculature, abnormal extracellular matrix (ECM), and limited lymphatic drainage) to deliver anticancer drugs with reduced systemic side effects. Liposomes are the most promising of such SDDSs and have been well investigated for cancer therapy. To improve the specificity, bioavailability, and anticancer efficacy of liposomes at the diseased sites, other strategies such as targeting ligands and stimulus-sensitive liposomes have been developed. This review highlights relevant surface functionalization techniques and stimuli-mediated drug release for enhanced delivery of anticancer agents at tumor sites, with a special focus on dual functionalization and design of multistimuli responsive liposomes.

The role of peptide-based therapeutics in oncotherapy

Cancer is the second leading cause of death worldwide, and the search for specialised therapy options has been a challenge for decades. The emergence of active targeted therapies provides the opportunity to treat cancerous tissues without harming healthy ones due to peculiar physiological changes. Herein, peptides and peptide analogs have been gaining a lot of attention over the last decade, especially for the on-site delivery of therapeutics to target tissues in order to achieve efficient and reliable cancer treatment. Combining peptides with highly efficient drug delivery platforms could potentially eliminate off-target adverse effects encountered during active targeting of conventional chemotherapeutics. Small size, ease of production and characterisation, low immunogenicity and satisfactory binding affinity of peptides offer some advantages over other complex targeting moiety, no wonder the market of peptide-based drugs continues to expand expeditiously. It is estimated that the global peptide drug market will be worth around USD 48.04 billion by 2025, with a compound annual growth rate of 9.4%. In this review, the current state of art of peptide-based therapeutics with special interest on tumour targeting peptides has been discussed. Moreover, various active targeting strategies such as the use functionalised peptides or peptide analogs are also elaborated.

Multi-stimuli-responsive, liposome-crosslinked poly(ethylene glycol) hydrogels for drug delivery

The development of hybrid hydrogels has been of great interest over recent decades, especially in the field of biomaterials. Such hydrogels provide various opportunities in tissue engineering, drug delivery, and regenerative medicine due to their ability to mimic cellular environments, sequester and release therapeutic agents, and respond to stimuli. Herein we report the synthesis and characterization of an injectable poly(ethylene glycol) hydrogel crosslinked via thiol-maleimide reactions and containing both chemically crosslinked temperature-sensitive liposomes (TSLs) and matrix metalloproteinase-sensitive peptide crosslinks. Rheological studies demonstrate that the hydrogel is mechanically stable and can be synthesized to achieve a range of physically applicable moduli. Experiments characterizing the in situ drug delivery and degradation of these materials indicate that the TSL gel responds to both thermal and enzymatic stimuli in a local environment. Doxorubicin, a widely used anticancer drug, was loaded in the TSLs with a high encapsulation efficiency and the subsequent release was temperature dependent. Finally, TSLs did not compromise viability and proliferation of human and murine fibroblasts, supporting the use of these hydrogel-linked liposomes as a thermo-responsive drug carrier for controlled release.

Triggered Drug Release From Liposomes: Exploiting the Outer and Inner Tumor Environment

Since more than 40 years liposomes have being extensively studied for their potential as carriers of anticancer drugs. The basic principle behind their use for cancer treatment consists on the idea that they can take advantage of the leaky vasculature and poor lymphatic drainage present at the tumor tissue, passively accumulating in this region. Aiming to further improve their efficacy, different strategies have been employed such as PEGlation, which enables longer circulation times, or the attachment of ligands to liposomal surface for active targeting of cancer cells. A great challenge for drug delivery to cancer treatment now, is the possibility to trigger release from nanosystems at the tumor site, providing efficacious levels of drug in the tumor. Different strategies have been proposed to exploit the outer and inner tumor environment for triggering drug release from liposomes and are the focus of this review.

Peptide-functionalized liposomes as therapeutic and diagnostic tools for cancer treatment

Clinically efficacious medication in anticancer therapy has been successfully designed with liposome-based nanomedicine. The liposomal formulation in cancer drug delivery can be facilitated with a functionalized peptide that mediates the specific drug delivery opportunities with increased drug penetrability, specific accumulation in the targeted site, and enhanced therapeutic efficacy. This review aims to focus on recent advances in peptide-functionalized liposomal formulation techniques in cancer diagnosis and treatment regarding recently published literature. It also will highlight different aspects of novel liposomal formulation techniques that incorporate surface functionalization with peptides for better anticancer effect and current challenges in peptide-functionalized liposomal drug formulation.

Potential drug delivery nanosystems for improving tumor penetration

Nanosystems, as one of the most important drug delivery systems, play a crucial rule in tumor therapy. However, the deep tumor penetration is retarded by the tumor physiological factors and nanomedicine properties. In this review, we firstly elaborate the factors which impact tumor penetration, including the tumor physiological factors and nanomedicine properties. Then, the latest and potential drug delivery nanosystems for improving tumor penetration are summarized and analyzed in detail. Moreover, recent combination therapies for improving penetration are described to enhance penetration. Finally, we summarize the typical clinical therapies of potential drug delivery nanosystems.

New Aspects of Ultrasound-Mediated Targeted Delivery and Therapy for Cancer

Ultrasound-mediated targeted delivery (UMTD), a novel delivery modality of therapeutic materials based on ultrasound, shows great potential in biomedical applications. By coupling ultrasound contrast agents with therapeutic materials, UMTD combines the advantages of ultrasound imaging and carrier, which benefit deep tissue penetration and high concentration aggregation. In this paper we introduced recent advances in ultrasound contrast agents and applications in tumor therapy. Ultrasound contrast agents were categorized by their functions, mainly including thermosensitive, pH-sensitive and photosensitive ultrasound contrast agents. The various applications of UMTD in tumor treatment were summarized as follows: drug therapy, transfection of anti-oncogene, RNA interference, vaccine immunotherapy, monoclonal antibody immunotherapy, adoptive cellular immunotherapy, cytokine immunotherapy, and so on. In the end, we elaborated on the current challenges and provided perspectives of UMTD for clinical applications.

Cancer Targeted Gene Therapy for Inhibition of Melanoma Lung Metastasis with eIF3i shRNA Loaded Liposomes

Eukaryotic translation initiation factors 3i (eIF3i) is a proto-oncogene that is overexpressed in various tumors, reducing its expression by eIF3i shRNA is a promising strategy to inhibit tumor growth or metastasis. Tumor cell is the target of eIF3i shRNA so that tumor-site accumulation could be important for fulfilling its therapeutic effect. Thus, the iRGD modified liposome (R-LP) was rationally synthesized to enhance the antitumor effect by active targeted delivery of eIF3i shRNA to B16F10 melanoma cells. R-LP encapsulating eIF3i shRNA gene (R-LP/sheIF3i) were prepared by a film dispersion method. The transfection experiment proves that R-LP could effectively transfect B16F10 cells. R-LP/sheIF3i notably restrained the migration, invasion, and adhesion of melanoma cells in vitro. In a mouse model of lung metastasis, R-LP/sheIF3i administered by intravenous injection suppressed pulmonary metastasis of melanoma by dramatically downregulated eIF3i expression and subsequently inhibiting tumor neovascularization and tumor cells proliferation in vivo. Our results provide a basis for tumor cells targeting strategies to reduce the expression of eIF3i by RNAi in the treatment of tumor metastasis.

Polyethylenimine-Based Nanogels for Biomedical Applications

Nanogels (NGs) are 3-dimensional (3D) networks composed of hydrophilic or amphiphilic polymer chains, allowing for effective and homogeneous encapsulation of drugs, genes, or imaging agents for biomedical applications. Polyethylenimine (PEI), possessing abundant positively charged amine groups, is an ideal platform for the development of NGs. A variety of effective PEI-based NGs have been designed and much effort has been devoted to study the relationship between the structure and function of the NGs. In particular, PEI-based NGs can be prepared either using PEI as the major NG component or using PEI as a crosslinker. This review reports the recent progresses in the design of PEI-based NGs for gene and drug delivery and for bioimaging applications with a target focus to tackle the diagnosis and therapy of cancer.

Thermosensitive Liposomes for Image-Guided Drug Delivery

Liposomes have been employed as cancer therapy clinically since the 1990s, with the primary benefit of reduced toxicity but no appreciable efficacy improvement. Thermosensitive liposomes (TSLs) are specifically formulated such that they release the encapsulated drug when exposed to hyperthermic temperatures in the fever range (~40-42°C) and have been investigated as cancer therapy for several decades, with first clinical trials initiated in the last decade. Combined with localized hyperthermia, TSLs allow precise drug delivery to a targeted region. Typically, the targeted tissue is exposed to localized hyperthermia facilitated by an image-guided hyperthermia device. Thus, TSLs enable image-guided drug delivery where drug is delivered to a tissue region identified by medical imaging. Recent TSL formulations are based on the more recent paradigm of intravascular triggered release, where drug is released rapidly (within seconds) while TSLs pass through the vasculature of the heated tissue region. The drug released within the blood then extravasates and is taken up by cancer cells. These TSLs enable up to 20-30 times higher tumor drug uptake compared to infusion of unencapsulated drug, and the dose locally delivered to the heated region can be modulated based on heating duration. This chapter reviews various TSL formulations, the different anticancer agents that have been encapsulated, as well as targeted cancer types. Further, the various hyperthermia devices that have been used for image-guided hyperthermia are reviewed, focusing on those that have been employed in human patients.

iRGD: A Promising Peptide for Cancer Imaging and a Potential Therapeutic Agent for Various Cancers

Poor penetration into the tumor parenchyma and the reduced therapeutic efficacy of anticancer drugs and other medications are the major problems in tumor treatment. A new tumor-homing and penetrating peptide, iRGD (CRGDK/RGPD/EC), can be effectively used to combine and deliver imaging agents or anticancer drugs into tumors. The different “vascular zip codes” expressed in different tissues can serve as targets for docking-based (synaptic) delivery of diagnostic and therapeutic molecules. αv-Integrins are abundantly expressed in the tumor vasculature, where they are recognized by peptides containing the RGD integrin recognition motif. The iRGD peptide follows a multistep tumor-targeting process: First, it is proteolytically cleaved to generate the CRGDK fragment by binding to the surface of cells expressing αv integrins (αvβ3 and αvβ5). Then, the fragment binds to neuropilin-1 and penetrates the tumor parenchyma more deeply. Compared with conventional RGD peptides, the affinity of iRGD for αv integrins is in the mid to low nanomolar range, and the CRGDK fragment has a stronger affinity for neuropilin-1 than that for αv integrins because of the C-terminal exposure of a conditional C-end Rule (CendR) motif (R/KXXR/K), whose receptor proved to be neuropilin-1. Consequently, these advantages facilitate the transfer of CRGDK fragments from integrins to neuropilin-1 and consequently deeper penetration into the tumor. Due to its specific binding and strong affinity, the iRGD peptide can deliver imaging agents and anticancer drugs into tumors effectively and deeply, which is useful in detecting the tumor, blocking tumor growth, and inhibiting tumor metastasis. This review aims to focus on the role of iRGD in the imaging and treatment of various cancers.

A chemo-photothermal synergetic antitumor drug delivery system: Gold nanoshell coated wedelolactone liposome

In this study, an antitumor drug delivery system, gold nanoshell coated wedelolactone liposomes (AuNS-Wed-Lip), were designed and synthesized. In the drug delivery system, wedelolactone liposome and gold-nanoshell were linked by l-cysteine, which had been shown an effective nanocarrier for antitumor drug delivery, on-demand drug release, and phototherapy under near-infrared (NIR) light irradiation. It was capable of absorbing 780-850 nm NIR light and converting light energy to heat rapidly. The hyperthermia promoted wedelolactone release rapidly from the systems. The release amount of AuNS-Wed-Lip under NIR irradiation reached up to 97.34% over 8 h, achieving the on-demand drug release. Moreover, a high inhibition rate up to 95.73% for 143B tumor cells by AuNS-Wed-Lip upon laser irradiation at 808 nm was observed. The excellent inhibition efficacy was also displayed in vivo antitumor study with S180 tumor-bearing mice. The results demonstrated that AuNS-Wed-Lip, as an antitumor drug delivery system, achieved chemo-photothermal synergetic effect, which has great potential in cancer therapy.

External temperature control of lymphatic drainage of thermo-sensitive nanomaterials

Nano-carrier-facilitated delivery of bioactive molecules into lymph nodes (LNs) has found application in the treatment and diagnosis of numerous immune-related diseases. Much work has focused on optimization of physicochemical properties of the nano-carrier to enhance lymphatic drainage passively, whereas active modulation of the quantity and timing of lymphatic delivery remains a significant challenge. Here, inspired by the success of thermo-modulation of tumor targeting, we have developed a simple external temperature control strategy to regulate the distribution of thermo-sensitive nanomaterials between the injection site and draining LNs. To demonstrate feasibility of this strategy, we injected Rhodamine-B-labeled poly(N-isopropylacrylamide) (RhB-PNIPAm) (2.5 kDa) into the footpad of mice at different initial temperatures - either below or above the lower critical solution temperature (LCST), followed by physical cooling of the injection site. We show that RhB-PNIPAm drained efficiently into the popliteal and inguinal nodes (pLNs, iLNs, respectively) with low levels of accumulation in major internal organs. Within the first two hours post-injection the rate of drainage was primarily dependent on the initial temperature of RhB-PNIPAm. However, over the course of 24 h, temperature gradient due to local cooling affected significantly the draining of the injection site, resulting in differential accumulation of RhB-PNIPAm in the proximal (pLNs) versus the distal (iLNs) nodes. This study provides a new methodology and insights for modulating in vivo lymphatic distribution of thermo-sensitive nanomaterials with implications in immune regulation and immunotherapy.

Lipoprotein-inspired penetrating nanoparticles for deep tumor-targeted shuttling of indocyanine green and enhanced photo-theranostics

Biomimetic iRGD-rHDL/ICG nanoparticles exhibited deep tumor targeted shuttling of indocyanine green and enhanced phototherapy.

Tumor targeting DVDMS-nanoliposomes for an enhanced sonodynamic therapy of gliomas

UTMD-assisted intelligent DVDMS encapsulate iRGD-Liposomes mediate SDT with deep tumor penetration and specific targeting ability enhanced anti-glioma efficacy.

Ultrasound-Targeted Delivery Technology: A Novel Strategy for Tumor- Targeted Therapy

Background:

Ultrasound has been widely used in clinical diagnosis because it is noninvasive, inexpensive, simple, and reproducible. With the development of molecular imaging, material science, and ultrasound contrast agents, ultrasound-targeted delivery technology has emerged. The interaction of ultrasound and molecular probes can be exploited to change the structures of cells and tissues in order to promote the targeted release of therapeutic substances to local tumors. The targeted delivery of drugs, genes, and gases would not only improve the efficacy of tumor treatment but also avoid the systemic toxicity and side effects caused by antitumor treatments. This technology was recently applied in clinical trials and showed enormous potential for clinical application.

Objective:

This article briefly introduces the characteristics of the tumor microenvironment and the principle of ultrasound-targeted delivery technology. To present recent progress in this field, this review focuses on the application of ultrasound-targeted delivery technology in tumor-targeted therapy, including drug delivery, gene transfection, and gas treatment.

Results:

The results of this study show that ultrasound-targeted delivery technology is a promising therapeutic strategy for tumor treatment.

Conclusion:

Ultrasound-targeted delivery technology shows promise with regard to cancer treatment.

RGD-modified polymer and liposome nanovehicles: Recent research progress for drug delivery in cancer therapeutics

Over the past few decades, as the demand for cancer treatment has increased, more rational treatment options (considering size, mode of administration, biocompatibility, efficacy, etc.) and plenty of specifically active targeted nanovehicles have been developed. Integrin receptors targeting are one of the most frequently used approaches because of its highly expressed in cancer cells. In particular, the arginine-glycine-aspartic acid (RGD) peptide and its derivatives have been widely used as ligands for integrin to increase direct targeting capabilies. Polymers as well as liposomes are commonly used as nanovehicles for drug delivery. A variety of work is focused on the RGD-modified polymer and liposome nanovehicles for cancer therapeutics. The goal of this article is to review the published literature in recent years concerning the RGD-modified liposome and polymer nanovehicles to highlight its successful designs for improving cancer therapy and discuss the current challenges as well as the possible development prospects.

The Detailed Comparison of Cell Death Detected by Annexin V-PI Counterstain Using Fluorescence Microscope, Flow Cytometry and Automated Cell Counter in Mammalian and Microalgae Cells

The evaluation of cell wellness is an important task for molecular biology research. This mainly comprises the assessment for morphology and viability of culturing cells. Annexin V-Propidium iodide counterstaining has been currently one of the common and easy methods to discriminate apoptotic and necrotic cell profiles. The method is operated by fluorescence-based detection of counterstain via laser beam-employed instruments including flow cytometer, fluorescence microscope and automated cell counter. The detection is primarily conducted based on the same principle; however the efficiency of instruments may vary. Here we evaluated the efficiency of those instruments for the clear-cut detection of cell death through various mammalian and microalgae cell lines. To the best of our knowledge, this is the first study revealing comparative analyses of apoptotic and necrotic cells in mammalian and microalgae cells using Annexin V-PI counterstain detected by flow cytometer, fluorescence microscope and automated cell counter. Fluorescence microscope and cell counter instruments were also tested and compared for the traditional trypan blue-based cell viability detection performance. For these, cell death was induced by UV-irradiation and/or bee venom for mammalian (pancreatic cancer, metastatic breast cancer and mouse fibroblasts) and microalgae cells (Chlorella vulgaris), respectfully. Findings postulated that automated cell counter and fluorescence microscopy revealed similar patterns for the detection by both counterstain and trypan blue in mammalian cells. Interestingly, flow cytometry did provide an accurate and significant detection for only one mammalian cell line when UV-treatment was followed by routine Annexin V-Propidium iodide counterstaining. Unlike, only flow cytometry revealed a significant change in the detection of death of microalgae cells by Annexin V-Propidium iodide method, but both Annexin and conventional trypan blue methods were not applicable for the automated cell counter and microscopic detections for microalgae cells. The related outputs propose that the obtaining reliable quantitation strongly depends on cell type and instruments used. These suggest the necessity of optimization and validation endeavors before any cell death detection initiative. The analytical outcomes present insights into detailed assessment of cell death detection of eukaryotic cells and provide a direction to researchers to consider.

Natural melanin-loaded nanovesicles for near-infrared mediated tumor ablation by photothermal conversion

Photothermal therapy requires a biocompatible material to absorb near-infrared (NIR) light and generate sufficient heat. Herein, we suggest natural melanin-loaded nanovesicles (melasicles) as photothermal therapeutic agents (PTA) for NIR mediated cancer therapy in vivo. The mean size of these melasicles was 140 ± 15 nm. They showed excellent colloidal stability. After irradiation from 808 nm NIR laser at 1.5 W cm^-2, the melasicles showed good photothermal conversion efficiencies both in vitro and in vivo. In drug release study, laser irradiation increased fluidity of vesicle membrane due to photothermal generation from melanin. Initial drug release in the laser irradiation group was higher than that in the no laser irradiation group. After injecting the melasicles into tail veins of CT-26 bearing mice, tumors were suppressed or eliminated after irradiation at 1.5 W cm^-2 for 5 min once or twice. These results suggest that melasicles could be used as attractive PTA for cancer therapy and localized drug release.

Thermosensitive Lipid Bilayer-Coated Mesoporous Carbon Nanoparticles for Synergistic Thermochemotherapy of Tumor

Thermochemotherapy exhibits a synergistic therapeutic efficiency for cancer, and the sensitivity of cancer cells to chemical drugs could be increased to a large extent at elevated temperature. In this work, a biocompatible nanocomposite thermosensitive mesoporous carbon nanoparticles (TSMCN) was prepared by covering a liposome on mesoporous carbon nanoparticles (MCN). The TSMCN had good photothermal efficiency and photostability. The doxorubicin (DOX)-loaded TSMCN (DOX/TSMCN) showed a slower release than the DOX-loaded MCN-COOH (DOX/MCN-COOH) both in simulated tumor environment and physiological environment. And release curves of DOX/TSMCN exposed to NIR laser exhibited the fast release property. The confocal laser scanning microscopy results illustrated that cellular uptake of DOX for DOX/TSMCN can be enhanced by NIR laser. The temperature of the tumor site reached up to 51.9 °C within 3 min after exposure to laser at 1.25 W/cm² power density, which is above the phase transition temperature ( T_m) of liposome (40.7 °C). The biodistribution of DOX in vivo indicated that NIR laser can prolong the retardation time of DOX in the tumor site. The results of both 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and antitumor efficiency elucidated that the DOX/TSMCN under NIR irradiation had a synergistic therapeutic effect for cancer. Thus, the TSMCN could be explored as a powerful nanoplatform that shows great prospect in thermochemotherapy of tumor therapy.

Redox/ultrasound dual stimuli-responsive nanogel for precisely controllable drug release

Schematic representation of the preparation and the strategy of redox/ultrasound triggered drug release of the nanogel system.