Stimuli-responsive drug delivery systems triggered by intracellular or subcellular microenvironments

Targeting lipid metabolism via nanomedicine: A prospective strategy for cancer therapy

Lipid metabolism has been increasingly recognized to play an influencing role in tumor initiation, progression, metastasis, and therapeutic drug resistance. Targeting lipid metabolic reprogramming represents a promising therapeutic strategy. Despite their structural complexity and poor targeting efficacy, lipid-metabolizing drugs, either used alone or in combination with chemotherapeutic agents, have been employed in clinical practice. The advent of nanotechnology offers new approaches to enhancing therapeutic effects, includingthe targeted delivery and integration of lipid metabolic reprogramming with chemotherapy, photodynamic therapy (PDT), and immunotherapy. The integrated nanoformulation, nanomedicine, could significantly advance the field of lipid metabolism therapy. In this review, we will briefly introduce the concept of cancer lipid metabolism reprogramming, then elaborate the latest advances in engineered nanomedicine for targeting lipid metabolism during cancer treatment, and finally provide our insights into future perspectives of nanomedicine for interference with lipid metabolism in the tumor microenvironment.

Blueprints for Better Drugs: The Structural Revolution in Nanomedicine

Structural nanomedicines are engineered constructs that arrange therapeutic components into well-defined architectures to maximize efficacy. Their multivalent, multifunctional design offers key advantages over unstructured formulations, including targeted delivery, expanded therapeutic windows, and enhanced target engagement. The mRNA COVID-19 vaccines exemplify their transformative potential. However, structural precision varies, and more well-defined architectures will streamline optimization, manufacturing, and regulation. Unlike small molecule drugs, nanomedicines within a batch are not identical. Identifying the most effective, least toxic structures will advance our understanding of structure-function relationships and therapeutic mechanisms. This work highlights structural nanomedicines─small molecules, nucleic acids, and biologics─to galvanize the field and drive innovation toward even safer, more effective treatments that benefit patients.

Progress and potential of nanobubbles for ultrasound-mediated drug delivery

INTRODUCTION

Despite much progress, nanomedicine-based drug therapies in oncology remain limited by systemic toxicity and insufficient particle accumulation in the tumor. To address these barriers, formulations responsive to external physical stimuli have emerged. One most promising system is the ultrasound stimulation of drug-loaded, gas-core particles (bubbles). Ultrasound induces bubble cavitation for cell and tissue permeabilization, triggers on-demand drug release, and provides opportunities for real-time imaging of delivery.

AREAS COVERED

Here, we focus on shell-stabilized, gas-core nanoparticles (also termed nanobubbles or ultrafine bubbles) and their role in ultrasound-mediated therapeutic delivery to tumors. This review frames the advantages of nanobubbles within the ongoing deficits in nanomedicine, describes mechanisms of ultrasound-mediated therapy, and details formulation techniques for nanobubble delivery systems. It then highlights the past decade of research in nanobubble-facilitated drug delivery for cancer therapy and anticipates new directions in the field.

EXPERT OPINION

Nanobubble ultrasound contrast agents offer a spatiotemporally triggerable therapeutic coupled with a safe, accessible imaging modality. Nanobubbles can be loaded with diverse therapeutic cargoes to treat disease and overcome numerous barriers limiting delivery to solid tumors. Close attention to formulation, characterization methods, acoustic testing parameters, and the biological mechanisms of nanobubble delivery will facilitate preclinical research toward clinical adoption.

Identification of functional biomarkers for personalized nanomedicine in advanced breast cancer in vitro models

Nanomedicines represent promising advanced therapeutics for the enhanced treatment of breast cancer, the primary cause of cancer-related deaths in women; however, the clinical translation of nanomedicines remains challenging. Advanced in vitro models of breast cancer may improve preclinical evaluations and the identification of biomarkers that aid the stratification of patients who would benefit from a given nanomedicine. In this study, we first developed a matrix-embedded breast cancer cell spheroid model representing the extracellular matrix and confirmed the faithful recapitulation of disease aggressiveness in vitro. We then characterized factors influencing nanomedicine drug release (i.e., cathepsin B levels/activity, reactive oxygen species levels, glutathione levels, and cytoplasmic pH values) and evaluated nanomedicine internalization and cytotoxicity evaluation in our spheroid model. We confirmed the reduced-to-oxidized glutathione ratio as a functional biomarker of disulfide linker-containing polypeptide-drug conjugate effectiveness. We then established a biobank of patient-derived breast cancer organoids that recapitulate clinical intra-tumor and inter-tumor heterogeneity as a more advanced model. Analysis in organoids revealed that patient-specific responses to a polypeptide-based nanomedicine correlated with cathepsin B levels, supporting the potential of the functional biomarker for patient-tailored nanomedicine selection. Our findings highlight that exhaustively characterized advanced in vitro models support the evaluation of nanomedicines and the identification of functional biomarkers.

Research progress of nano drug delivery systems in the anti-tumor treatment of traditional Chinese medicine monomers

Tumors pose a serious threat to global public health and are usually treated from two aspects: tumor cells and tumor microenvironment. Compared with traditional chemotherapy drugs, traditional Chinese medicine (TCM) monomers have advantages in tumor treatment, such as multiple targets, multiple levels and synergistic intervention. However, most TCM active ingredients have disadvantages such as poor water solubility and stability, which restrict their clinical application. Nano drug delivery systems have the functions of improving the bioavailability of TCM anti-tumor active ingredients, enhancing tissue targeting, achieving controlled drug release, and inhibiting tumor multidrug resistance. Compared with free monomers, they have higher therapeutic effects and fewer side effects. This article summarizes five commonly used anti-tumor TCM monomer nanocarriers, including lipid nanomaterials, exosomes, polymer micelles, carbon nanotubes, and dendrimers, and explains their anti-tumor mechanisms after combining with TCM, such as inhibiting tumor cell proliferation and metastasis, regulating tumor microenvironment, etc. At the same time, the potential of nano drug delivery systems combined with radiotherapy and immunotherapy is discussed, as well as the current problems of potential toxicity, long-term stability, and complex amplification process, as well as future development directions, aiming to provide a reference for promoting the clinical application of nano drug delivery systems for TCM anti-tumor active ingredients.

Evaluating the Drug Delivery Capacity of 3D Coordination Polymer for Anticancer Drugs

We synthesized {[Cd2(dTMP)2(4,4'-azpy)2(H2O)2] ⋅ 3(O)}n a novel three-dimensional metal nucleotide coordination polymer (CP-1). An assessment of the CP-1 binding affinity for anticancer drugs was conducted using molecular dynamic simulations. The virtual screening results depict that CP-1 has a lot of potential for encapsulating the anthracycline anticancer drug doxorubicin (DOX). It hasn't yet been investigated how to accomplish high loading capacity, efficiency, and controlled release of DOX in dTMP-based 3D metal coordination polymers. Utilizing DOX as a drug model and our system as a drug-loading vehicle, we used UV-visible and circular dichroism titrations to examine the effects of its encapsulation and release. The mechanism of drug loading and release was investigated through pH-responsive behavior by adjusting the pH value to 8, 7, 6, and 5. The results indicate the CP-1 has a robust affinity for DOX at pH 7, which facilitates its loading on 3D porous coordination polymer. However, the maximum cumulative drug release of 87.11 % was observed at pH 5. The higher correlation coefficient (R2) was obtained at pH 5 with the Higuchi equation. It indicated that the drug released was primarily controlled with the diffusion mechanism. The CP-1 polymer's ability to encapsulate DOX while also permitting a possible controlled-release mechanism is confirmed by the combined insights from the experimental findings, energy graphs, RMSD analysis, and radius of gyration (Rg) data from MD simulations.

Drug delivery for platinum therapeutics

Cancer remains a severe threat to human health. Platinum drugs, such as cisplatin (CDDP), oxaliplatin, and carboplatin, are extensively utilized for treating various cancers and have become the primary drugs in first-line treatments for numerous solid tumors due to their effective anticancer properties. However, their side effects, including drug resistance, nephrotoxicity and ototoxicity, limit the clinical application. Therefore, there is an urgent need to develop targeted delivery and controlled release systems for platinum drugs to address the disadvantages, enhancing tumor accumulation and improving therapeutic effects. In this review, we first review the progress of platinum drugs, their anticancer mechanism, clinical applications and limitations. Then, we comprehensively summarize the platinum-based delivery using drug carriers and responsive strategies. We especially highlight the platinum-delivery formulations in ongoing clinical trials. Finally, we provide perspectives for this field. The review could provide an increasingly in-depth understanding of platinum therapeutics and motivate increasing delivery tactics to overcome the limitations of platinum application.

A Methionine Allocation Nanoregulator for the Suppression of Cancer Stem Cells and Support to the Immune Cells by Epigenetic Regulation

Epigenetic dysregulation is prevalent in human cancers, affecting gene expression and metabolic patterns to meet the demands of malignant evolution and abnormal epigenetic processes, and resulting in a protumor immune microenvironment. Tumors require a steady supply of methionine for maintaining epigenetic flexibility, which is the only exogenous precursor of methyl donor S-adenosylmethionine for methylation, crucial for their resistance to therapies and survival in a nutrient-deficient microenvironment. Thus, tumor cells upregulate the Lat4 transporter to compete and deprive methionine in the microenvironment, sustaining their malignant phenotypes and also impairing immune cell functions. Addressing this methionine addiction is the key to overcoming drug resistance and improving immune response. Despite the challenge of lacking specific Lat4 inhibitors, an oxaliplatin prodrug crosslinked fluorinated polycation/anti-Lat4 small interfering RNA complex nanoregulator (AS-F-NP) has been designed and developed here. This nanoregulator restricted the greedy methionine uptake of tumor cells by knocking down Lat4, which in turn inhibited the malignant evolution of the tumor while restoring the viability and function of tumor-infiltrating immune cells.

Engineered Intelligent Microenvironment Responsive Prodrug Conjugates Navigated by Bioinspired Lipoproteins for Reversing Liver Fibrosis

Liver fibrosis (LF) is characterized by excessive production of reactive oxygen species (ROS), abnormal activation of hepatic stellate cells (HSCs), and subsequent extracellular matrix (ECM) deposition. The complexity of multiple interrelated pathways involved in this process makes it challenging for monotherapy to achieve the desired therapeutic effects. To address this issue, this study designs a ROS-activated heterodimer conjugate (VTO) to collaboratively alleviate LF. Additionally, a biomimetic high-density lipoprotein is utilized for encapsulation, resulting in the formation of PL-VTO, which enables natural liver targeting. Once PL-VTO is delivered to the fibrotic liver, it can respond and release both parent drugs upon encountering the high ROS microenvironment, effectively scavenge ROS, induce quiescence of activated HSCs, and reduce collagen deposition, ultimately reversing LF. Overall, this study presents a feasible and versatile nanotherapeutic approach to enhance the prodrug-driven treatment of LF.

Enhanced combination therapy through tumor microenvironment-activated cellular uptake and ROS-sensitive drug release using a dual-sensitive nanogel

Although the co-delivery of chemotherapeutic and photodynamic agents has been studied for years, developing a simple and efficient nanoplatform for high co-delivery efficiency remains a challenge for clinical applications. In this study, we prepared a reactive oxygen species (ROS) and pH dual-sensitive nanogel for the co-encapsulation of doxorubicin (DOX) and indocyanine green (ICG)-conjugated bovine serum albumin (BSA) via a simple inverse miniemulsion polymerization process. This was followed by modification with pegylated cell-penetrating peptides (CPPs) containing citraconic anhydride (CDM) linkers, which are sensitive to weakly acidic microenvironments (pH 6.5). Pegylation endowed the nanogel with extended blood circulation, while the de-shielding of polyethylene glycol (PEG) exposed the CPPs, significantly enhancing cellular uptake. Upon near-infrared (NIR) irradiation, ROS generated by ICG not only killed tumor cells but also triggered the release of DOX through nanogel disintegration. Serial experiments verified the nanogel's high co-delivery efficiency, tumor tissue matrix microenvironment-triggered cellular uptake, controlled drug release, and synergistic antitumor effects. Therefore, this dual-sensitive nanogel, prepared via inverse miniemulsion polymerization, offers a facile approach to improving co-delivery efficiency for combination therapy.

Advance in peptide-based drug development: delivery platforms, therapeutics and vaccines

The successful approval of peptide-based drugs can be attributed to a collaborative effort across multiple disciplines. The integration of novel drug design and synthesis techniques, display library technology, delivery systems, bioengineering advancements, and artificial intelligence have significantly expedited the development of groundbreaking peptide-based drugs, effectively addressing the obstacles associated with their character, such as the rapid clearance and degradation, necessitating subcutaneous injection leading to increasing patient discomfort, and ultimately advancing translational research efforts. Peptides are presently employed in the management and diagnosis of a diverse array of medical conditions, such as diabetes mellitus, weight loss, oncology, and rare diseases, and are additionally garnering interest in facilitating targeted drug delivery platforms and the advancement of peptide-based vaccines. This paper provides an overview of the present market and clinical trial progress of peptide-based therapeutics, delivery platforms, and vaccines. It examines the key areas of research in peptide-based drug development through a literature analysis and emphasizes the structural modification principles of peptide-based drugs, as well as the recent advancements in screening, design, and delivery technologies. The accelerated advancement in the development of novel peptide-based therapeutics, including peptide-drug complexes, new peptide-based vaccines, and innovative peptide-based diagnostic reagents, has the potential to promote the era of precise customization of disease therapeutic schedule.

Tumor microenvironment as a target for developing anticancer hydrogels

OBJECTIVE

It has been reported that cancer cells get protected by a complex and rich multicellular environment i.e. the tumor microenvironment (TME) consisting of varying immune cells, endothelial cells, dendritic cells, fibroblasts, etc. This manuscript is aimed at the characteristic features of TME considered as potential target(s) for developing smart anticancer hydrogels.

SIGNIFICANCE

The stimuli-specific drug delivery systems especially hydrogels that can respond to the characteristic features of TME are fabricated for treating cancer. For developing anticancer formulations, TME targeting can be considered an alternative way as it enhances the cytotoxic potential and reduces the unwanted effects. This manuscript shall be of quite interest to academicians, researchers, and clinicians engaged in oncology.

METHODS

The manuscript was prepared by using the data available in the public domain in online resources such as Google Scholar, PubMed, Science Direct, Scopus, Web of Science, Research Gate, etc.

RESULTS

Smart hydrogels, sensitive to some specific features of TME such as low pH, high concentration of glutathione, specific enzymes, etc., are promising anticancer formulations as these improve the efficacy and lower the side effects of chemotherapy.

CONCLUSION

The stimuli-responsive hydrogels have been gaining more attention for delivering cytotoxic drugs to the TME in response to specific stimuli. The stimuli-responsive hydrogels, comprising of cytotoxic drug(s) and specific polymers have some special features such as similarity with biological matrix, ability to respond to various internal as well as external stimuli, improved permeability, porosity, biocompatibility, resemblance with soft living tissues, etc.; and are considered as the promising anticancer candidates.

Cryoshocked Adipocytes Mediated Dual-Modal Strategy Combining Photodynamic Therapy and Triptolide Palmitate for Pulmonary Metastatic Melanoma Treatment

Pulmonary metastasis represents one of the most prevalent forms of metastasis in advanced melanoma, with mortality rates reaching 70%. Current treatments including chemotherapy, targeted therapy, and immunotherapy frequently exhibit limited efficacy or present high costs. To address these clinical needs, this study presents a biomimetic drug delivery system (Ce6-pTP-CsA) utilizing cryoshocked adipocytes (CsA) encapsulating the prodrug triptolide palmitate (pTP) and the photosensitizer Ce6, exploiting the characteristic of tumor cells to recruit and lipolyze adipocytes for energy. CsA substantially enhances the drug-loading capacity of adipocytes, with its particle size characteristics enabling targeted delivery of pTP to the lungs. The combination of photodynamic therapy (PDT) and pTP activates the caspase cascade, promoting apoptosis in tumor cells. Notably, the cleavage of disulfide bonds in pTP depletes glutathione (GSH), reducing its scavenging effect on reactive oxygen species (ROS) and enhancing the efficacy of PDT. Results demonstrate that Ce6-pTP-CsA effectively inhibits the proliferation and invasion of pulmonary metastatic melanoma cells in vitro and induces apoptosis, while significantly suppressing lung metastasis of SCID mice models in vivo. In conclusion, this novel biomimetic drug delivery system based on adipocytes provides a promising strategy for targeted therapy in pulmonary metastatic melanoma.

Metal-Protein Hybrid Materials: Unlocking New Frontiers in Biomedical Applications

Metal-protein hybrid materials represent a novel class of functional materials that exhibit exceptional physicochemical properties and tunable structures, rendering them remarkable applications in diverse fields, including materials engineering, biocatalysis, biosensing, and biomedicine. The design and development of multifunctional and biocompatible metal-protein hybrid materials have been the subject of extensive research and a key aspiration for practical applications in clinical settings. This review provides a comprehensive analysis of the design strategies, intrinsic properties, and biomedical applications of these hybrid materials, with a specific emphasis on their potential in cancer therapy, drug and vaccine delivery, antibacterial treatments, and tissue regeneration. Through rational design, stable metal-protein hybrid materials can be synthesized using straightforward methods, enabling them with therapeutic, delivery, immunomodulatory, and other desired functionalities. Finally, the review outlines the existing limitations and challenges associated with metal-protein hybrid materials and evaluates their potential for clinical translation, providing insights into their practical implementation within biomedical applications.

Macrophage Membrane-Cloaked ROS-Responsive Albumin Nanoplatforms for Targeted Delivery of Curcumin to Alleviate Acute Liver Injury

Developing low-toxicity, high-efficacy, and fast-acting strategies to manage acute liver injury (ALI) is critical due to its rapid progression and potential for severe outcomes. Curcumin (CUR) has shown promise in ALI therapy due to its ability to modulate the inflammatory microenvironment by scavenging reactive oxygen species (ROS). Nevertheless, CUR is highly hydrophobic limiting its bioavailability and effective in vivo transport, which hinders its further application. In this study, we developed an inflammatory microenvironment-targeted drug delivery system by covalently coupling human serum albumin (HSA) with ROS-sensitive thioketal linkers and loading it with CUR to form nanoparticles (HSA-TK/CUR). These nanoparticles were then coated with a macrophage membrane (CM@HSA-TK/CUR), resulting in negatively charged spherical particles (≈ -23.26 mV) with an average particle size of around 165 nm. ROS responsiveness was confirmed through drug release assays and enhanced ROS depletion was further demonstrated by Diacetyldichlorofluorescein (DCFH-DA) ROS detection experiments. CM@HSA-TK/CUR treatment resulted in a 94.7% reduction in ROS levels in inflammatory cells. In addition, cellular uptake and in vivo distribution experiments demonstrated that camouflaging HSA-TK/CUR with macrophage membranes significantly enhanced its targeting of the inflammatory microenvironment. The findings revealed that CM@HSA-TK/CUR rapidly accumulated in the injured liver within 6 h, inhibited the production of pro-inflammatory factors (IL-1β, IL-6, and TNF-α), shifted macrophage polarization from M1 to M2 in vivo, and protected hepatocytes from oxidative stress-associated cell death, significantly attenuating the inflammatory response in ALI mice. In conclusion, CM@HSA-TK/CUR has excellent potential in treating mice with ALI.

Hyaluronic acid regulated facile synthesis of size-tunable multifunctional nanomedicine for effective cancer therapy

The complex and heterogeneous nature of cancer necessitates the development of innovative multifunctional nanomedicines (MN). Hyaluronic acid (HA) is a functional carbohydrate polysaccharide that is widely used in various biomedical fields. In this study, we employed HA as a stabilizer and regulator for the synthesis of a size-tunable nanomedicine comprising ferric ions, doxorubicin, and epigallocatechin gallate (EGCG), referred to as HDE-MN, for cancer therapy. A change in the HA ratio can yield HDE-MNs with sizes varying from ~20 nm to over 100 nm. Modified HA can respond to hyaluronidase (HAase) to provide controllable pH/HAase dual-responsive drug release for improved cancer therapy. Moreover, HA can mediate the targeted delivery of HDE-MNs both in vitro and in vivo to cancer cells. In addition, HDE-MNs reversed multidrug resistance owing to the incorporation of EGCG, inducing ferroptosis due to the involvement of ferric ions. More importantly, HDE-MNs have a photothermal conversion effect, enabling photothermal therapy, photothermally enhanced drug release, and ferroptosis, which collectively contribute to significantly improved cancer therapy. Therefore, the HDE-MNs with laser irradiation achieved full ablation of the in vivo tumors. Together with its good biocompatibility, HDE-MNs may be promising for effective cancer therapy.

Tumor-Targeted Catalytic Immunotherapy

Cancer immunotherapy holds significant promise for improving cancer treatment efficacy; however, the low response rate remains a considerable challenge. To overcome this limitation, advanced catalytic materials offer potential in augmenting catalytic immunotherapy by modulating the immunosuppressive tumor microenvironment (TME) through precise biochemical reactions. Achieving optimal targeting precision and therapeutic efficacy necessitates a thorough understanding of the properties and underlying mechanisms of tumor-targeted catalytic materials. This review provides a comprehensive and systematic overview of recent advancements in tumor-targeted catalytic materials and their critical role in enhancing catalytic immunotherapy. It highlights the types of catalytic reactions, the construction strategies of catalytic materials, and their fundamental mechanisms for tumor targeting, including passive, bioactive, stimuli-responsive, and biomimetic targeting approaches. Furthermore, this review outlines various tumor-specific targeting strategies, encompassing tumor tissue, tumor cell, exogenous stimuli-responsive, TME-responsive, and cellular TME targeting strategies. Finally, the discussion addresses the challenges and future perspectives for transitioning catalytic materials into clinical applications, offering insights that pave the way for next-generation cancer therapies and provide substantial benefits to patients in clinical settings.

Platinum(IV)-Backboned Polymer Prodrug-Functionalized Manganese Oxide Nanoparticles for Enhanced Lung Cancer Chemoimmunotherapy via Amplifying Stimulator of Interferon Genes Activation

The stimulator of interferon genes (STING) pathway exhibits great potential in remodeling the immunosuppressive tumor microenvironment and initiating antitumor immunity. However, how to effectively activate STING and avoid undesired toxicity after systemic administration remains challenging. Herein, platinum(IV)-backboned polymer prodrug-coated manganese oxide nanoparticles (DHP/MnO2NP) with pH/redox dual responsive properties are developed to precisely release cisplatin and Mn2+ in the tumor microenvironment and synergistically amplify STING activation. In vitro, we demonstrate that DHP/MnO2NP can effectively induce tumor cell DNA damage and leak into the cytoplasm, cooperating with Mn2+ to promote STING activation and significantly upregulate the expression of proinflammatory cytokines. Additionally, DHP/MnO2NP can selectively release cisplatin and Mn2+ to mediate tumor killing while reducing toxicity to normal cells. In vivo, DHP/MnO2NP exerted increased therapeutic efficacy by inducing STING activation and initiating robust antitumor immunity. Specifically, DHP/MnO2NP effectively skewed tumor-associated macrophages toward a proinflammatory phenotype and upregulated the expression of proinflammatory cytokines in tumors by up to 99-fold relative to the control. And the infiltration of CD8+ T cells was also significantly increased. When STING signaling was blocked, the antitumor effects and immunostimulatory efficacy of DHP/MnO2NP were significantly inhibited. Moreover, DHP/MnO2NP possess the advantage of enhanced tumor homing and retention, resulting in stronger and longer-lasting anticancer effects. Overall, DHP/MnO2NP provide a potential platform for potentiating cancer chemoimmunotherapy and hold promise for precision treatment.

Bioresponsive Polymeric Nanoparticles: From Design, Targeted Therapy to Cancer Immunotherapy

Bioresponsive polymeric nanoparticles (NPs) that are capable of delivering and releasing therapeutics and biotherapeutics to target sites have attracted vivid interest in cancer therapy and immunotherapy. In contrast to enthusiastic evolution in the academic world, the clinical translation of these smart systems is scarce, partly due to concerns about safety, stability, complexity, and scalability. The moderate targetability, responsivity, and benefits are other concerns. In the past 17 years, we have devoted ourselves to exploring elegant strategies to address the above basic and translational problems by introducing diverse functional groups and/or targeting ligands to safe biomedical materials, such as biodegradable polymers and water-soluble polymers. This minimal modification is critical for further clinical translation. We have tailor-made various bioresponsive NPs including shell-sheddable and/or acid-sensitive biodegradable NPs, disulfide-cross-linked biodegradable micelles and polymersomes, and blood-brain barrier (BBB)-permeable NPs, to target different tumors. This perspective provides an overview of our work path toward targeted nanomedicines and personalized vaccines, which might inspire clinical translation and future research on cancer therapy.

Cell inspired delivery system equipped with natural membrane structures in applications for rescuing ischemic stroke

Ischemic stroke (IS), accounting for 87 % of stroke incidences, constitutes a paramount health challenge owing to neurological impairments and irreversible tissue damage arising from cerebral ischemia. Chief among therapeutic obstacles are the restrictive penetration of the blood-brain barrier (BBB) and insufficient targeting precision, hindering the accumulation of drugs in ischemic brain areas. Motivated by the remarkable capabilities of natural membrane-based delivery vehicles in achieving targeted delivery and traversing the BBB, thanks to their biocompatible architecture and bioactive components, numerous membrane-engineered systems such as cells, cell membranes and extracellular vesicles have emerged as promising platforms to augment IS treatment efficacy with the help of nanotechnology. This review consolidates the primary pathological manifestations following IS, elucidates the unique functionalities of natural membrane drug delivery systems (DDSs) with nanotechnology, as well as delineates the structural characteristics of various natural membranes alongside rational design strategies employed. The review illuminates both the potential and challenges encountered when employing natural membrane DDSs in IS drug therapy, offering fresh perspectives and insights for devising efficacious and practical delivery systems tailored to IS intervention.

NIPAm Microgels Synthesised in Water: Tailored Control of Particles' Size and Thermoresponsive Properties

Microgels, combining the properties of hydrogels and microparticles, are emerging as versatile materials for varied applications such as drug delivery and sensing, although the precise control of particle size remains a challenge. Advances in synthetic methodologies have provided new tools for tailoring of properties, however costs and scalability of the processes remains a limitation. We report here the water-based synthesis of a library of N-isopropylacrylamide-based microgels covalently crosslinked with varying contents of N,N'-methylenebisacrylamide. The results highlight the versatility of water as a synthetic medium, which yields large and monodisperse microgels, with excellent control over size. Dynamic light scattering data demonstrate that by increasing the total monomer concentration from 1 to 3 wt%, the particle size is increased by up to 4.9-fold. Crosslinker content allows fine-tuning of microgel size, with greater relevance for functionalised microgels. Functional co-monomers such as N-(3-aminopropyl)methacrylamide hydrochloride and N-(hydroxymethyl)acrylamide are shown to influence size and thermoresponsive behaviour, with hydrogen-bonding monomers reducing particle size and increasing the volume phase transition temperature by 2 °C. Positively charged monomers show a size reduction upon heating but provide colloidal stability at temperatures up to 60 °C. These findings emphasize the importance of tailoring synthetic conditions and formulations to optimize microgel properties for specific applications.

Recent advances in reactive oxygen species (ROS)-responsive drug delivery systems for photodynamic therapy of cancer

Reactive oxygen species (ROS)-responsive drug delivery systems (DDSs) have garnered significant attention in cancer research because of their potential for precise spatiotemporal drug release tailored to high ROS levels within tumors. Despite the challenges posed by ROS distribution heterogeneity and endogenous supply constraints, this review highlights the strategic alliance of ROS-responsive DDSs with photodynamic therapy (PDT), enabling selective drug delivery and leveraging PDT-induced ROS for enhanced therapeutic efficacy. This review delves into the biological importance of ROS in cancer progression and treatment. We elucidate in detail the operational mechanisms of ROS-responsive linkers, including thioether, thioketal, selenide, diselencide, telluride and aryl boronic acids/esters, as well as the latest developments in ROS-responsive nanomedicines that integrate with PDT strategies. These insights are intended to inspire the design of innovative ROS-responsive nanocarriers for enhanced cancer PDT.

Nucleus-targeted Silencer nanoplatform regulating ZEB1-AS1 in head and neck squamous cell carcinoma therapy

Long noncoding RNAs have emerged as key players in the progression of head and neck squamous cell carcinoma (HNSC). Among them, ZEB1-AS1 was identified as an upregulated candidate in HNSC through comprehensive analysis of RNA-sequencing datasets. Here, elevated ZEB1-AS1 expression was correlated with poor prognosis in HNSC patients. Further investigations demonstrated that downregulation of ZEB1-AS1 induced epithelial-mesenchymal transition and increased sensitivity to cisplatin in Cal27 cells, while its upregulation reversed these effects, underscoring its pivotal role in tumor metastasis and cisplatin resistance in Cal27 cells. Mechanistically, ZEB1-AS1, located in cytoplasm and nucleus, directly regulated the expression of ZEB1, thereby influencing the expression of μ opioid receptor (MOR) and implicating in cancer progression. To advance clinical translation, we employed a nucleus-targeting nanoparticle platform for efficient delivery of a mixture of antisense oligonucleotides and siRNA (Silencer), effectively manipulating ZEB1-AS1 expression in vitro and in vivo. Besides, a predictive model for HNSC patients was developed by analyzing the expression levels of ZEB1-AS1, ZEB1, and MOR in the HNSC datasets. Our study underscored the critical role of ZEB1-AS1 in HNSC and its potential as a therapeutic target. By elucidating its functional mechanisms and utilizing a nucleus-targeting nanoparticle platform for efficient delivery, we proved the potential of ZEB1-AS1-targeted therapies in HNSC.

Nanoparticle-Based Nitric Oxide Donors: Exploring Their Antimicrobial and Anti-Biofilm Capabilities

Background: Nitric oxide (NO) is an antimicrobial and anti-biofilm agent with significant potential for combating biofilm-associated infections and antibiotic resistance. However, owing to its high reactivity due to the possession of a free radical and short half-life (1-5 s), the practical application of NO in clinical settings is challenging. Objectives: This review explores the development of NO-releasing nanoparticles that provide a controlled, targeted delivery system for NO, enhancing its antimicrobial efficacy while minimizing toxicity. The review discusses various NO donors, nanoparticle platforms, and how NO disrupts biofilm formation and eradicates pathogens. Additionally, we examine the highly encouraging and inspiring results of NO-releasing nanoparticles against multidrug-resistant strains and their applications in medical and environmental contexts. This review highlights the promising role of NO-based nanotechnologies in overcoming the challenges posed by increasing antibiotic resistance and biofilm-associated infections. Conclusions: Although NO donors and nanoparticle delivery systems show great potential for antimicrobial and anti-biofilm uses, addressing challenges related to controlled release, toxicity, biofilm penetration, resistance, and clinical application is crucial.

Rational design of a poly-L-glutamic acid-based combination conjugate for hormone-responsive breast cancer treatment

Breast cancer represents the most prevalent tumor type worldwide, with hormone-responsive breast cancer the most common subtype. Despite the effectiveness of endocrine therapy, advanced disease forms represent an unmet clinical need. While drug combination therapies remain promising, differences in pharmacokinetic profiles result in suboptimal ratios of free drugs reaching tumors. We identified a synergistic combination of bisdemethoxycurcumin and exemestane through drug screening and rationally designed star-shaped poly-L-glutamic acid-based combination conjugates carrying these drugs conjugated through pH-responsive linkers for hormone-responsive breast cancer treatment. We synthesized/characterized single and combination conjugates with synergistic drug ratios/loadings. Physicochemical characterization/drug release kinetics studies suggested that lower drug loading prompted a less compact conjugate conformation that supported optimal release. Screening in monolayer and spheroid breast cancer cell cultures revealed that combination conjugates possessed enhanced cytotoxicity/synergism compared to physical mixtures of single-drug conjugates/free drugs; moreover, a combination conjugate with the lowest drug loading outperformed remaining conjugates. This candidate inhibited proliferation-associated signaling, reduced inflammatory chemokine/exosome levels, and promoted autophagy in spheroids; furthermore, it outperformed a physical mixture of single-drug conjugates/free drugs regarding cytotoxicity in patient-derived breast cancer organoids. Our findings highlight the importance of rational design and advanced in vitro models for the selection of polypeptide-based combination conjugates.

Bioorthogonal chemistry-based prodrug strategies for enhanced biosafety in tumor treatments: current progress and challenges

Cancer is a significant global health challenge, and while chemotherapy remains a widely used treatment, its non-specific toxicity and broad distribution can lead to systemic side effects and limit its effectiveness against tumors. Therefore, the development of safer chemotherapy alternatives is crucial. Prodrugs hold great promise, as they remain inactive until they reach the cancer site, where they are selectively activated by enzymes or specific factors, thereby reducing side effects and improving targeting. However, subtle differences in the microenvironments between tumors and normal tissue may still result in unintended cytotoxicity. Bioorthogonal reactions, known for their selectivity and precision without interfering with natural biochemical processes, are gaining attention. When combined with prodrug strategies, these reactions offer the potential to create highly effective chemotherapy drugs. This review examines the safety and efficacy of prodrug strategies utilizing various bioorthogonal reactions in cancer treatment.

A nanoprodrug derived from branched poly (ethylene glycol) recognizes prostate-specific membrane antigen to precisely suppress prostate cancer progression

Prostate-specific membrane antigen (PSMA) is overexpressed in 80-90 % of prostate cancers (PCa) and is widely used as a diagnostic and therapeutic biomarker. Docetaxel (DTX), an FDA-approved anti-microtubule drug, is commonly employed to manage metastatic castration-resistant PCa; however, DTX therapy is often associated with severe side effects. One promising strategy to mitigate these side effects is the development of nanomedicine by loading small molecules into biocompatible vectors. Poly (ethylene glycol) (PEG) has been extensively used in clinical settings for this purpose, with PEGylated drugs demonstrating significant success. Compared to linear PEG, branched PEG (multi-arm PEG) provides enhanced stability for nanomedicines. In this study, we developed a novel nanoprodrug 4armPEG-Docetaxel DCL (4armPEG-DD) by conjugating a 4-arm PEG with DTX via a reduction-sensitive disulfide bond and further modifying it with 2-[3-[5-amino-1-carboxypentyl]-ureido]-pentanedioic acid (DCL), a PSMA-targeting ligand. Both in vitro and in vivo results demonstrated that the designed nanoprodrug specifically recognized PSMA-positive PCa cells and effectively released DTX in response to the intracellular reducing environment, leading to potent cytotoxic effects on PSMA-positive prostate tumors. Importantly, 4armPEG-DD exhibited improved in vivo safety compared to small-molecule DTX. Thus, we propose that 4armPEG-DD represents a promising candidate for the clinical treatment of PSMA-positive PCa.

Stimuli-Responsive Polymeric Nanocarriers Accelerate On-Demand Drug Release to Combat Glioblastoma

Glioblastoma multiforme (GBM) is a highly malignant brain tumor with a poor prognosis and limited treatment options. Drug delivery by stimuli-responsive nanocarriers holds great promise for improving the treatment modalities of GBM. At the beginning of the review, we highlighted the stimuli-active polymeric nanocarriers carrying therapies that potentially boost anti-GBM responses by employing endogenous (pH, redox, hypoxia, enzyme) or exogenous stimuli (light, ultrasonic, magnetic, temperature, radiation) as triggers for controlled drug release mainly via hydrophobic/hydrophilic transition, degradability, ionizability, etc. Modifying these nanocarriers with target ligands further enhanced their capacity to traverse the blood-brain barrier (BBB) and preferentially accumulate in glioma cells. These unique features potentially lead to more effective brain cancer treatment with minimal adverse reactions and superior therapeutic outcomes. Finally, the review summarizes the existing difficulties and future prospects in stimuli-responsive nanocarriers for treating GBM. Overall, this review offers theoretical guidelines for developing intelligent and versatile stimuli-responsive nanocarriers to facilitate precise drug delivery and treatment of GBM in clinical settings.

Nanomedicines with Versatile GSH-Responsive Linkers for Cancer Theranostics

Glutathione (GSH)-responsive nanomedicines have generated significant interest in biochemistry, oncology, and material sciences due to their diverse applications, including chemical and biological sensors, diagnostics, and drug delivery systems. The effectiveness of these smart GSH-responsive nanomedicines depends critically on the choice of GSH-responsive linkers. Despite their crucial role, comprehensive reviews of GSH-responsive linkers are scarce, revealing a gap in the current literature. This review addresses this gap by systematically summarizing various GSH-responsive linkers and exploring their potential applications in cancer treatment. We provide an overview of the mechanisms of action of these linkers and their bioapplications, evaluating their advantages and limitations. The insights presented aim to guide the development of advanced GSH-responsive agents for cancer diagnosis and therapy.

Design and evaluation of nanoscale materials with programmed responsivity towards epigenetic enzymes

Self-assembled materials capable of modulating their assembly properties in response to specific enzymes play a pivotal role in advancing 'intelligent' encapsulation platforms for biotechnological applications. Here, we introduce a previously unreported class of synthetic nanomaterials that programmatically interact with histone deacetylase (HDAC) as the triggering stimulus for disassembly. These nanomaterials consist of co-polypeptides comprising poly(acetyl L-lysine) and poly(ethylene glycol) blocks. Under neutral pH conditions, they self-assemble into particles. The hydrodynamic diameters of particles were typically withing the range of 108-190 nm, depending on degree of acetylation of the hydrophobic block. However, their stability is compromised upon exposure to HDACs, depending on enzyme concentration and exposure time. Our investigation, utilizing HDAC8 as the model enzyme, revealed that the primary mechanism behind disassembly involves a decrease in amphiphilicity within the block copolymer due to the deacetylation of lysine residues within the particles' hydrophobic domains. To elucidate the response mechanism, we encapsulated a fluorescent dye within these nanoparticles. Upon incubation with HDAC, the nanoparticle structure collapsed, leading to controlled release of the dye over time. Notably, this release was not triggered by denatured HDAC8, other proteolytic enzymes like trypsin, or the co-presence of HDAC8 and its inhibitor. We also demonstrated the biocompatibility and cellular effects of these materials in the context of drug delivery in different types of anticancer cell lines, such as MIA PaCa-2, PANC-1, cancer like stem cells (CSCs), and non-cancerous HPNE cells. We observed that the release of a model drug (such as a STAT3 pathway inhibitor, Napabucasin) can be loaded into these nanoparticles, with >90% of the dosage can be released over 3 h under the influence of HDAC8 enzyme in a controlled fashion. Further, we conducted a comprehensive computational study to unveil the possible interaction mechanism between enzymes and particles. By drawing parallels to the mechanism of naturally occurring histone proteins, this research represents a pioneering step toward developing functional materials capable of harnessing the activity of epigenetic enzymes such as HDACs.

Targeted codelivery of doxorubicin and oleanolic acid by reduction responsive hyaluronic acid-based prodrug nano-micelles for enhanced antitumor activity and reduced toxicity

Chemotherapy remains one of the most commonly used strategies in cancer treatment but suffers from damages to healthy tissues and organs. How to precisely co-deliver two or more drugs with different mechanisms of action to the tumors for synergistic function is a challenge for chemotherapy. Herein, Oleanolic acid (OA)-conjugated Hyaluronic acid self-assembled nano-micelles loaded with Doxorubicin (DOX) (HSO NPs/DOX) were constructed for CD44 positive cancer targeted codelivery of DOX and OA. HSO NPs/DOX exhibited reduction triggered drug release under high concentration of glutathione, more efficient uptake by 4T1 breast cancer cells than free DOX leading to higher cytotoxicity, pro-apoptotic, and migration inhibitory activities against 4T1 cells. The ex vivo biodistribution experiment demonstrated more HSO NPs/DOX were accumulated in the tumor tissues than free DOX and less in the non-tumor tissues after injections in 4T1 tumor bearing mice. More importantly, synergistic anti-tumor effects of DOX and OA were obtained using HSO NPs/DOX in 4T1 breast tumor-bearing mice and toxicity of DOX to liver and heart were circumvented through regulating the Nuclear Factor kappa-light-chain-enhancer of activated B cells (NF-κB) and Silent Information Regulator 1 (Sirt1) expressions. Taken together, HSO NPs/DOX may become a promising codelivery system for chemotherapeutics in cancer therapy.

Disulfide bonds as a molecular switch of enzyme-activatable anticancer drug precise release for fluorescence imaging and enhancing tumor therapy

Enzyme-activatable drug delivery systems have been developed for cancer diagnosis and therapy. However, targeted intracellular drug delivery is a challenge for precisely tumor imaging and therapy due to the increased stability of copolymer nanoparticles (NPs) is accompanied by a notable decrease in enzyme degradation. Herein, disulfide bond was designed as an enzyme-activatable molecular switch of SS-P(G2)2/DOX NPs. The copolymer NPs consists of polyvinylpyrrolidone (PVP) with disulfide bonds in the center and enzyme-degradable peptide dendrites (Phe-Lys) to form dendritic-linear-dendritic triblock copolymers (TBCs). The amphiphilic TBCs could be split into two identical amphiphilic diblock copolymers (DBCs) by glutathione (GSH) in cancer cells specifically while maintaining the same hydrophilic-lipophilic equilibrium. This structural transformation significantly reduced the stability of copolymer NPs and enhanced sensitivity of DOX release by cathepsin B-activated. Subsequently, the released DOX acted as an indicator of fluorescence imaging and chemotherapy drug for cancer cells. The polymeric NPs achieved excellent drug-loaded stability and prolonged blood circulation in vivo, and realized fluorescence imaging and specific cancer cell killing capabilities by responding to the overexpression of GSH and cathepsin B in tumor cells. Furthermore, the copolymer NPs demonstrated excellent blood compatibility and biosafety. Therefore, a novel strategy based on one tumor marker acting as the switch for another tumor microenvironment responsive drug delivery system could be designed for tumor intracellular imaging and chemotherapy.

Dual pH/redox-responsive size-switchable polymeric nano-carrier system for tumor microenvironment DTX release

Innovation chemotherapeutic nano drug delivery systems (NDDSs) with various pharmacological achievement have become one of the hopeful therapeutic strategies in cancer therapy. This study focused on low pH, and high levels of glutathione (GSH) as two prominent characteristics of the tumor microenvironment (TME) to design a novel TME-targeted pH/redox dual-responsive P (AMA-co-DMAEMA)-b-PCL-SS-PCL-b-P (AMA-co-DMAEMA) nanoparticles (NPs) for deep tumor penetration and targeted anti-tumor therapy. The positively charged NPs exhibit strong electrostatic interactions with negatively charged cell membranes, significantly enhancing cellular uptake. Moreover, these NPs possess the unique size-shrinkable property, transitioning from 98.24 ± 27.78 to 45.56 ± 20.62 nm within the TME. This remarkable size change fosters an impressive uptake of approximately 100% by MDA-MB-231 cells within just 30 min, thereby greatly improving drug delivery efficiency. This size switchability enables passive targeting through the enhanced permeability and retention (EPR) effect, facilitating deep penetration into tumors. The NPs also demonstrate improved pH/redox-triggered drug release (∼70% at 24 h) within the TME and exhibit no toxicity in cell viability test. The cell cycle results of treated cells with docetaxel (DTX)-loaded NPs revealed G2/M (84.6 ± 1.16%) arrest. The DTX-loaded NPs showed more apoptosis (62.6 ± 3.7%) than the free DTX (51.8 ± 3.2%) in treated cells. The western blot and RT-PCR assays revealed that apoptotic genes and proteins expression of treated cells were significantly upregulated with the DTX-loaded NPs vs. the free DTX (Pvalue<.001). In conclusion, these findings suggest that this novel-engineered NPs holds promise as a TME-targeted NDDS.

Redox-manipulating nanocarriers for anticancer drug delivery: a systematic review

Spatiotemporally controlled cargo release is a key advantage of nanocarriers in anti-tumor therapy. Various external or internal stimuli-responsive nanomedicines have been reported for their ability to increase drug levels at the diseased site and enhance therapeutic efficacy through a triggered release mechanism. Redox-manipulating nanocarriers, by exploiting the redox imbalances in tumor tissues, can achieve precise drug release, enhancing therapeutic efficacy while minimizing damage to healthy cells. As a typical redox-sensitive bond, the disulfide bond is considered a promising tool for designing tumor-specific, stimulus-responsive drug delivery systems (DDS). The intracellular redox imbalance caused by tumor microenvironment (TME) regulation has emerged as an appealing therapeutic target for cancer treatment. Sustained glutathione (GSH) depletion in the TME by redox-manipulating nanocarriers can exacerbate oxidative stress through the exchange of disulfide-thiol bonds, thereby enhancing the efficacy of ROS-based cancer therapy. Intriguingly, GSH depletion is simultaneously associated with glutathione peroxidase 4 (GPX4) inhibition and dihydrolipoamide S-acetyltransferase (DLAT) oligomerization, triggering mechanisms such as ferroptosis and cuproptosis, which increase the sensitivity of tumor cells. Hence, in this review, we present a comprehensive summary of the advances in disulfide based redox-manipulating nanocarriers for anticancer drug delivery and provide an overview of some representative achievements for combinational therapy and theragnostic. The high concentration of GSH in the TME enables the engineering of redox-responsive nanocarriers for GSH-triggered on-demand drug delivery, which relies on the thiol-disulfide exchange reaction between GSH and disulfide-containing vehicles. Conversely, redox-manipulating nanocarriers can deplete GSH, thereby enhancing the efficacy of ROS-based treatment nanoplatforms. In brief, we summarize the up-to-date developments of the redox-manipulating nanocarriers for cancer therapy based on DDS and provide viewpoints for the establishment of more stringent anti-tumor nanoplatform.

Sonodynamic effect based on vancomycin-loaded microbubbles or meropenem-loaded microbubbles enhances elimination of different biofilms and bactericidal efficacy

Aims

This study investigated vancomycin-microbubbles (Vm-MBs) and meropenem (Mp)-MBs with ultrasound-targeted microbubble destruction (UTMD) to disrupt biofilms and improve bactericidal efficiency, providing a new and promising strategy for the treatment of device-related infections (DRIs).

Methods

A film hydration method was used to prepare Vm-MBs and Mp-MBs and examine their characterization. Biofilms of methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli were treated with different groups. Biofilm biomass differences were determined by staining. Thickness and bacterial viability were observed with confocal laser scanning microscope (CLSM). Colony counts were determined by plate-counting. Scanning electron microscopy (SEM) observed bacterial morphology.

Results

The Vm-MBs and Mp-MBs met the experimental requirements. The biofilm biomass in the Vm, Vm-MBs, UTMD, and Vm-MBs + UTMD groups was significantly lower than in the control group. MRSA and E. coli biofilms were most notably damaged in the Vm-MBs + UTMD group and Mp-MBs + UTMD group, respectively, with mean 21.55% (SD 0.08) and 19.73% (SD 1.25) remaining in the biofilm biomass. Vm-MBs + UTMD significantly reduced biofilm thickness and bacterial viability (p = 0.005 and p < 0.0001, respectively). Mp-MBs + UTMD could significantly decrease biofilm thickness and bacterial viability (allp < 0.001). Plate-counting method showed that the numbers of MRSA and E. coli bacterial colonies were significantly lower in the Vm-MBs + UTMD group and the Mp, Mp-MBs, UTMD, Mp-MBs + UTMD groups compared to the control group (p = 0.031). SEM showed that the morphology and structure of MRSA and E. coli were significantly damaged in the Vm-MBs + UTMD and Mp-MBs + UTMD groups.

Conclusion

Vm-MBs or Mp-MBs combined with UTMD can effectively disrupt biofilms and protectively release antibiotics under ultrasound mediation, significantly reducing bacterial viability and improving the bactericidal effect of antibiotics.

Delivery Strategy to Enhance the Therapeutic Efficacy of Liver Fibrosis via Nanoparticle Drug Delivery Systems

Liver fibrosis (LF) is a pathological repair reaction caused by a chronic liver injury that affects the health of millions of people worldwide, progressing to life-threatening cirrhosis and liver cancer without timely intervention. Due to the complexity of LF pathology, multiple etiological characteristics, and the deposited extracellular matrix, traditional drugs cannot reach appropriate targets in a time-space matching way, thus decreasing the therapeutic effect. Nanoparticle drug delivery systems (NDDS) enable multidrug co-therapy and develop multifactor delivery strategies targeting pathological processes, showing great potential in LF therapy. Based on the pathogenesis and the current clinical treatment status of LF, we systematically elucidate the targeting mechanism of NDDS used in the treatment of LF. Subsequently, we focus on the progress of drug delivery applications for LF, including combined delivery for the liver fibrotic pathological environment, overcoming biological barriers, precise intracellular regulation, and intelligent responsive delivery for the liver fibrotic microenvironment. We hope that this review will inspire the rational design of NDDS for LF in the future in order to provide ideas and methods for promoting LF regression and cure.

Macrocycle-Based Supramolecular Drug Delivery Systems: A Concise Review

Efficient delivery of therapeutic agents to the lesion site or specific cells is an important way to achieve "toxicity reduction and efficacy enhancement". Macrocycles have always provided many novel ideas for drug or gene loading and delivery processes. Specifically, macrocycles represented by crown ethers, cyclodextrins, cucurbit[n]urils, calix[n]arenes, and pillar[n]arenes have unique properties, which are different cavity structures, good biocompatibility, and good stability. Benefited from these diverse properties, a variety of supramolecular drug delivery systems can be designed and constructed to effectively improve the physical and chemical properties of guest molecules as needed. This review provides an outlook on the current application status and main limitations of macrocycles in supramolecular drug delivery systems.

Beyond Nanoparticle-Based Intracellular Drug Delivery: Cytosol/Organelle-Targeted Drug Release and Therapeutic Synergism

Nanoparticle (NP)-based drug delivery systems are conceived to solve poor water-solubility and chemical/physical instability, and their purpose expanded to target specific sites for maximizing therapeutic effects and minimizing unwanted events of payloads. Targeted sites are also narrowed from organs/tissues and cells to cytosol/organelles. Beyond specific site targeting, the particular release of payloads at the target sites is growing in importance. This review overviews various issues and their general strategies during multiple steps, from the preparation of drug-loaded NPs to their drug release at the target cytosol/organelles. In particular, this review focuses on current strategies for "first" delivery and "later" release of drugs to the cytosol or organelles of interest using specific stimuli in the target sites. Recognizing or distinguishing the presence/absence of stimuli or their differences in concentration/level/activity in one place from those in another is applied to stimuli-triggered release via bond cleavage or nanostructural transition. In addition, future directions on understanding the intracellular balance of stimuli and their counter-stimuli are demonstrated to synergize the therapeutic effects of payloads released from stimuli-sensitive NPs.

A Self-Amplifying ROS-Responsive Nanoplatform for Simultaneous Cuproptosis and Cancer Immunotherapy

Cuproptosis is an emerging cell death pathway that depends on the intracellular Cu ions. Elesclomol (ES) as an efficient Cu ionophore can specifically transport Cu into mitochondria and trigger cuproptosis. However, ES can be rapidly removed and metabolized during intravenous administration, leading to a short half-life and limited tumor accumulation, which hampers its clinical application. Here, the study develops a reactive oxygen species (ROS)-responsive polymer (PCP) based on cinnamaldehyde (CA) and polyethylene glycol (PEG) to encapsulate ES-Cu compound (EC), forming ECPCP. ECPCP significantly prolongs the systemic circulation of EC and enhances its tumor accumulation. After cellular internalization, the PCP coating stimulatingly dissociates exposing to the high-level ROS, and releases ES and Cu, thereby triggering cell death via cuproptosis. Meanwhile, Cu2+-stimulated Fenton-like reaction together with CA-stimulated ROS production simultaneously breaks the redox homeostasis, which compensates for the insufficient oxidative stress treated with ES alone, in turn inducing immunogenic cell death of tumor cells, achieving simultaneous cuproptosis and immunotherapy. Furthermore, the excessive ROS accelerates the stimuli-dissociation of ECPCP, forming a positive feedback therapy loop against tumor self-alleviation. Therefore, ECPCP as a nanoplatform for cuproptosis and immunotherapy improves the dual antitumor mechanism of ES and provides a potential optimization for ES clinical application.

Dendritic Polymer-Based Nanomedicines Remodel the Tumor Stroma: Improve Drug Penetration and Enhance Antitumor Immune Response

The dense extracellular matrix (ECM) in solid tumors, contributed by cancer-associated fibroblasts (CAFs), hinders penetration of drugs and diminishes their therapeutic outcomes. A sequential treatment strategy of remodeling the ECM via a CAF modifier (dasatinib, DAS) is proposed to promote penetration of an immunogenic cell death (ICD) inducer (epirubicin, Epi) via apoptotic vesicles, ultimately enhancing the treatment efficacy against breast cancer. Dendritic poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA)-based nanomedicines (poly[OEGMA-Dendron(G2)-Gly-Phe-Leu-Gly-DAS] (P-DAS) and poly[OEGMA-Dendron(G2)-hydrazone-Epi] (P-Epi)) are developed for sequential delivery of DAS and Epi, respectively. P-DAS reprograms CAFs to reduce collagen by downregulating collagen anabolism and energy metabolism, thereby reducing the ECM deposition. The regulated ECM can enhance tumor penetration of P-Epi to strengthen its ICD effect, leading to an amplified antitumor immune response. In breast cancer-bearing mice, this approach alleviates the ECM barrier, resulting in reduced tumor burden and increased cytotoxic T lymphocyte infiltration, and more encouragingly, synergizes effectively with anti-programmed cell death 1 (PD-1) therapy, significantly inhibiting tumor growth and preventing lung metastasis. Furthermore, systemic toxicity is barely detectable after sequential treatment with P-DAS and P-Epi. This approach opens a new avenue for treating desmoplastic tumors by metabolically targeting CAFs to overcome the ECM barrier.

Biodynamer Nano-Complexes and -Emulsions for Peptide and Protein Drug Delivery

Background

Therapeutic proteins and peptides offer great advantages compared to traditional synthetic molecular drugs. However, stable protein loading and precise control of protein release pose significant challenges due to the extensive range of physicochemical properties inherent to proteins. The development of a comprehensive protein delivery strategy becomes imperative accounting for the diverse nature of therapeutic proteins.

Methods

Biodynamers are amphiphilic proteoid dynamic polymers consisting of amino acid derivatives connected through pH-responsive dynamic covalent chemistry. Taking advantage of the amphiphilic nature of the biodynamers, PNCs and DEs were possible to be prepared and investigated to compare the delivery efficiency in drug loading, stability, and cell uptake.

Results

As a result, the optimized PNCs showed 3-fold encapsulation (<90%) and 5-fold loading capacity (30%) compared to DE-NPs. PNCs enhanced the delivery efficiency into the cells but aggregated easily on the cell membrane due to the limited stability. Although DE-NPs were limited in loading capacity compared to PNCs, they exhibit superior adaptability in stability and capacity for delivering a wider range of proteins compared to PNCs.

Conclusion

Our study highlights the potential of formulating both PNCs and DE-NPs using the same biodynamers, providing a comparative view on protein delivery efficacy using formulation methods.

Advances in Engineered Nanoparticles for the Treatment of Ischemic Stroke by Enhancing Angiogenesis

Angiogenesis, or the formation of new blood vessels, is a natural defensive mechanism that aids in the restoration of oxygen and nutrition delivery to injured brain tissue after an ischemic stroke. Angiogenesis, by increasing vessel development, may maintain brain perfusion, enabling neuronal survival, brain plasticity, and neurologic recovery. Induction of angiogenesis and the formation of new vessels aid in neurorepair processes such as neurogenesis and synaptogenesis. Advanced nano drug delivery systems hold promise for treatment stroke by facilitating efficient transportation across the the blood-brain barrier and maintaining optimal drug concentrations. Nanoparticle has recently been shown to greatly boost angiogenesis and decrease vascular permeability, as well as improve neuroplasticity and neurological recovery after ischemic stroke. We describe current breakthroughs in the development of nanoparticle-based treatments for better angiogenesis therapy for ischemic stroke employing polymeric nanoparticles, liposomes, inorganic nanoparticles, and biomimetic nanoparticles in this study. We outline new nanoparticles in detail, review the hurdles and strategies for conveying nanoparticle to lesions, and demonstrate the most recent advances in nanoparticle in angiogenesis for stroke treatment.

Glutathione-triggered prodrugs: Design strategies, potential applications, and perspectives

The burgeoning prodrug strategy offers a promising avenue toward improving the efficacy and specificity of cytotoxic drugs. Elevated intracellular levels of glutathione (GSH) have been regarded as a hallmark of tumor cells and characteristic feature of the tumor microenvironment. Considering the pivotal involvement of elevated GSH in the tumorigenic process, a diverse repertoire of GSH-triggered prodrugs has been developed for cancer therapy, facilitating the attenuation of deleterious side effects associated with conventional chemotherapeutic agents and/or the attainment of more efficacious therapeutic outcomes. These prodrug formulations encompass a spectrum of architectures, spanning from small molecules to polymer-based and organic-inorganic nanomaterial constructs. Although the GSH-triggered prodrugs have been gaining increasing interests, a comprehensive review of the advancements made in the field is still lacking. To fill the existing lacuna, this review undertakes a retrospective analysis of noteworthy research endeavors, based on a categorization of these molecules by their diverse recognition units (i.e., disulfides, diselenides, Michael acceptors, and sulfonamides/sulfonates). This review also focuses on explaining the distinct benefits of employing various chemical architecture strategies in the design of these prodrug agents. Furthermore, we highlight the potential for synergistic functionality by incorporating multiple-targeting conjugates, theranostic entities, and combinational treatment modalities, all of which rely on the GSH-triggering. Overall, an extensive overview of the emerging field is presented in this review, highlighting the obstacles and opportunities that lie ahead. Our overarching goal is to furnish methodological guidance for the development of more efficacious GSH-triggered prodrugs in the future. By assessing the pros and cons of current GSH-triggered prodrugs, we expect that this review will be a handful reference for prodrug design, and would provide a guidance for improving the properties of prodrugs and discovering novel trigger scaffolds for constructing GSH-triggered prodrugs.

Covalent organic frameworks-derived carbon nanospheres based nanoplatform for tumor specific synergistic therapy via oxidative stress amplification and calcium overload

Combinational therapy in cancer treatment that integrates the merits of different therapies is an effective approach to improve therapeutic outcomes. Herein, a simple nanoplatform (N-CNS-CaO2-HA/Ce6 NCs) that synergized chemodynamic therapy (CDT), photodynamic therapy (PDT), photothermal therapy (PTT), and Ca2+ interference therapy (CIT) has been developed to combat hypoxic tumors. With high photothermal effect, excellent peroxidase-like activity, and inherent mesoporous structure, N-doped carbon nanospheres (N-CNSs) were prepared via in situ pyrolysis of an established nanoscale covalent organic frameworks (COFs) precursor. These N-CNSs acted as PTT/CDT agents and carriers for the photosensitizer chlorin e6 (Ce6), thereby yielding a minimally invasive PDT/PTT/CDT synergistic therapy. Hyaluronic acid (HA)-modified CaO2 nanoparticles (CaO2-HA NPs) coated on the surface of the nanoplatform endowed the nanoplatform with O2/H2O2 self-supply capability to respond to and modulate the tumor microenvironment (TME), which greatly facilitated the tumor-specific performance of CDT and PDT. Moreover, the reactive oxygen species (ROS) produced during PDT and CDT enhanced the Ca2+ overloading due to CaO2 decomposition, amplifying the intracellular oxidative stress and leading to mitochondrial dysfunction. Notably, the HA molecules not only increased the cancer-targeting efficiency but also prevented CaO2 degradation during blood circulation, providing double insurance of tumor-selective CIT. Such a nanotherapeutic system possessed boosted antitumor efficacy with minimized systemic toxicity and showed great potential for treating hypoxic tumors.

Injectable Thermo-Responsive Peptide Hydrogels and Its Enzyme Triggered Dynamic Self-Assembly

Endogenous stimuli-responsive injectable hydrogels hold significant promise for practical applications due to their spatio-temporal controllable drug delivery. Herein, we report a facile strategy to construct a series of in situ formation polypeptide hydrogels with thermal responsiveness and enzyme-triggered dynamic self-assembly. The thermo-responsive hydrogels are from the diblock random copolymer mPEG-b-P(Glu-co-Tyr). The L-glutamic acid (Glu) segments with different γ-alkyl groups, including methyl, ethyl, and n-butyl, offer specific secondary structure, facilitating the formation of hydrogel. The L-tyrosine (Tyr) residues not only provide hydrogen-bond interactions and thus adjust the sol-gel transition temperatures, but also endow polypeptide enzyme-responsive properties. The PTyr segments could be phosphorylated, and the phosphotyrosine copolymers were amphiphilies, which could readily self-assemble into spherical aggregates and transform into sheet-like structures upon dephosphorylation by alkaline phosphatase (ALP). P(MGlu-co-Tyr/P) and P(MGlu-co-Tyr) copolymers showed good compatibility with both MC3T3-E1 and Hela cells, with cell viability above 80% at concentrations up to 1000 μg/mL. The prepared injectable polypeptide hydrogel and its enzyme-triggered self-assemblies show particular potential for biomedical applications.

Diselenide-Bridged Doxorubicin Dimeric Prodrug: Synthesis and Redox-Triggered Drug Release

The diselenide bond has attracted intense interest in redox-responsive drug delivery systems (DDSs) in tumor chemotherapy, due to its higher sensitivity than the most investigated bond, namely the disulfide bond. Here, a diselenide-bridged doxorubicin dimeric prodrug (D-DOXSeSe) was designed by coupling two doxorubicin molecules with a diselenodiacetic acid (DSeDAA) molecule via α-amidation, as a redox-triggered drug self-delivery system (DSDS) for tumor-specific chemotherapy. The drug release profiles indicated that the D-DOXSeSe could be cleaved to release the derivatives selenol (DOX-SeH) and seleninic acid (DOX-SeOOH) with the triggering of high GSH and H2O2, respectively, indicating the double-edged sword effect of the lower electronegativity of the selenide atom. The resultant solubility-controlled slow drug release performance makes it a promising candidate as a long-acting DSDS in future tumor chemotherapy. Moreover, the interaction between the conjugations in the design of self-immolation traceless linkers was also proposed for the first time as another key factor for a desired precise tumor-specific chemotherapy, besides the conjugations themselves.

Unlocking the Mitochondria for Nanomedicine-based Treatments: Overcoming Biological Barriers, Improving Designs, and Selecting Verification Techniques

Enhanced targeting approaches will support the treatment of diseases associated with dysfunctional mitochondria, which play critical roles in energy generation and cell survival. Obstacles to mitochondria-specific targeting include the presence of distinct biological barriers and the need to pass through (or avoid) various cell internalization mechanisms. A range of studies have reported the design of mitochondrially-targeted nanomedicines that navigate the complex routes required to influence mitochondrial function; nonetheless, a significant journey lies ahead before mitochondrially-targeted nanomedicines become suitable for clinical use. Moving swiftly forward will require safety studies, in vivo assays confirming effectiveness, and methodologies to validate mitochondria-targeted nanomedicines' subcellular location/activity. From a nanomedicine standpoint, we describe the biological routes involved (from administration to arrival within the mitochondria), the features influencing rational design, and the techniques used to identify/validate successful targeting. Overall, rationally-designed mitochondria-targeted-based nanomedicines hold great promise for precise subcellular therapeutic delivery.

NIR-responsive carboxymethyl-cellulose hydrogels containing thioketal-linkages for on-demand drug delivery system

Near-infrared (NIR) light-responsive hydrogels have emerged as a highly promising strategy for effective anticancer therapy owing to the remotely controlled release of chemotherapeutic molecules with minimal invasive manner. In this study, novel NIR-responsive hydrogels were developed from reactive oxygen species (ROS)-cleavable thioketal cross-linkers which possessed terminal tetrazine groups to undergo a bio-orthogonal inverse electron demand Diels Alder click reaction with norbornene modified carboxymethyl cellulose. The hydrogels were rapidly formed under physiological conditions and generated N2 gas as a by-product, which led to the formation of porous structures within the hydrogel networks. A NIR dye, indocyanine green (ICG) and chemotherapeutic doxorubicin (DOX) were co-encapsulated in the porous network of the hydrogels. Upon NIR-irradiation, the hydrogels showed spatiotemporal release of encapsulated DOX (>96 %) owing to the cleavage of thioketal bonds by interacting with ROS generated from ICG, whereas minimal release of encapsulated DOX (<25 %) was observed in the absence of NIR-light. The in vitro cytotoxicity results revealed that the hydrogels were highly cytocompatible and did not induce any toxic effect on the HEK-293 cells. In contrast, the DOX + ICG-encapsulated hydrogels enhanced the chemotherapeutic effect and effectively inhibited the proliferation of Hela cancer cells when irradiated with NIR-light.

Tumor Microenvironment ROS/pH Cascade-Responsive Supramolecular Nanoplatform with ROS Regeneration Property for Enhanced Hepatocellular Carcinoma Therapy

The low targeted drug delivery efficiency, including poor tumor accumulation and penetration and uncontrolled drug release, leads to the failure of cancer therapy. Herein, a multifunctional supramolecular nanoplatform loading triptolide (TPL/PBAETK@GA NPs) was fabricated via the host-guest interaction between glycyrrhetinic-acid-modified poly(ethylene glycol)-adamantanecarboxylic acid moiety and reactive oxygen species (ROS)/pH cascade-responsive copolymer poly(β-amino esters)-thioketal (TK)-β-cyclodextrin. TPL/PBAETK@GA NPs could accumulate in hepatocellular carcinoma (HCC) tissue effectively, mediated by nanoscale advantage and GA' recognition to specific receptors. The elevated concentration of ROS in tumor microenvironment (TME) quickly breaks the TK linkages, causing the detachment of shell (cyclodextrin) CD layer. Then, the accompanying negative-to-positive charge-reversal of NPs was realized via the PBAE moiety protonation under the slightly acidic TME, significantly enhancing the NPs' cellular internalization. Remarkably, the pH-responsive endo/lysosome escape of PBAE core triggered intracellular TPL burst release, promoting the cancer cell apoptosis, autophagy, and intracellular ROS generation, leading to the self-amplification of ROS in TME. Afterward, the ROS positive-feedback loop was generated to further promote size-shrinkage and charge-reversal of NPs. Both in vitro and in vivo tests verified that TPL/PBAETK@GA NPs produced a satisfactory anti-HCC therapy outcome. Collectively, this study offers a potential appealing paradigm to enhance TPL-based HCC therapy outcomes via multifunctionalized supramolecular nanodrugs.