A combinational chemo-immune therapy using an enzyme-sensitive nanoplatform for dual-drug delivery to specific sites by cascade targeting

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.

Mitochondria-Targeted Multifunctional Nanoprodrugs by Inhibiting Metabolic Reprogramming for Combating Cisplatin-Resistant Lung Cancer

How to address the resistance of cisplatin (CDDP) has always been a clinical challenge. The resistance mechanism of platinum-based drugs is very complex, including nuclear DNA damage repair, apoptosis escape, and tumor metabolism reprogramming. Tumor cells can switch between mitochondrial oxidative phosphorylation (OXPHOS) and glycolysis and develop resistance to chemotherapy drugs through metabolic variability. In addition, due to the lack of histone protection and a relatively weak damage repair ability, mitochondrial DNA (mtDNA) is more susceptible to damage, which in turn affects mitochondrial OXPHOS and can become a potential target for platinum-based drugs. Therefore, mitochondria, as targets of anticancer drugs, have become a hot topic in tumor resistance research. This study constructed a self-assembled nanotargeted drug delivery system LND-SS-Pt-TPP/HA-CD. β-Cyclodextrin-grafted hydronic acid (HA-CD)-encapsulated prodrug nanoparticles can target CD44 on the tumor surface and further deliver the prodrug to intracellular mitochondria through a triphenylphosphine group (TPP+). Disulfide bonds can be selectively degraded by glutathione (GSH) in mitochondria, releasing lonidamine (LND) and the cisplatin prodrug (Pt(IV)). Under the action of GSH and ascorbic acid, Pt(IV) is further reduced to cisplatin (Pt(II)). Cisplatin can cause mtDNA damage, induce mitochondrial dysfunction and mitophagy, and then affect mitochondrial OXPHOS. Meanwhile, LND can reduce the hexokinase II (HK II) level, induce destruction of mitochondria, and block energy supply by glycolysis inhibition. Ultimately, this self-assembled nano targeted delivery system can synergistically kill cisplatin-resistant lung cancer cells, which supplies an overcome cisplatin resistance choice via the disrupt mitochondria therapy.

Unravelling the role of tumor microenvironment responsive nanobiomaterials in spatiotemporal controlled drug delivery for lung cancer therapy

Design and development of efficient drug delivery technologies that impart site-specificity is the need of the hour for the effective treatment of lung cancer. The emergence of materials science and nanotechnology partially helped drug delivery scientists to achieve this objective. Various stimuli-responsive materials that undergo degradation at the pathological tumor microenvironment (TME) have been developed and explored for drug delivery applications using nanotechnological approaches. Nanoparticles (NPs), owing to their small size and high surface area to volume ratio, demonstrated enhanced cellular internalization, permeation, and retention at the tumor site. Such passive accumulation of stimuli-responsive materials helped to achieve spatiotemporally controlled and targeted drug delivery within the tumors. In this review, we discussed various stimuli-physical (interstitial pressure, temperature, and stiffness), chemical (pH, hypoxia, oxidative stress, and redox state), and biological (receptor expression, efflux transporters, immune cells, and their receptors or ligands)-that are characteristic to the TME. We mentioned an array of biomaterials-based nanoparticulate delivery systems that respond to these stimuli and control drug release at the TME. Further, we discussed nanoparticle-based combinatorial drug delivery strategies. Finally, we presented our perspectives on challenges related to scale-up, clinical translation, and regulatory approvals.

Self-assembled copper-based nanoparticles for enzyme catalysis-enhanced chemodynamic/photodynamic/antiangiogenic tritherapy against hepatocellular carcinoma

As an emerging cancer treatment strategy, reactive oxygen species-based tumor catalytic therapies face enormous challenges due to hypoxia and the overexpression of glutathione (GSH) in the tumor microenvironment. Herein, a self-assembled copper-based nanoplatform, TCCHA, was designed for enzyme-like catalysis-enhanced chemodynamic/photodynamic/antiangiogenic tritherapy against hepatocellular carcinoma. TCCHA was fabricated from Cu2+, 3,3'-dithiobis (propionohydrazide), and photosensitizer chlorine e6 via a facile one-pot self-assembly strategy, after which an aldehyde hyaluronic acid was coated, followed by loading of the antivascular drug AL3818. The obtained TCCHA nanoparticles exhibited pH/GSH dual-responsive drug release behaviors and multienzymatic activities, including Fenton, glutathione peroxidase-, and catalase-like activities. TCCHA, a redox homeostasis disruptor, promotes ⋅OH generation and GSH depletion, thus increasing the efficacy of chemodynamic therapy. TCCHA, which has catalase-like activity, can also reinforce the efficacy of photodynamic therapy by amplifying O2 production. In vivo, TCCHA efficiently inhibited tumor angiogenesis and suppressed tumor growth without apparent systemic toxicity. Overall, this study presents a facile strategy for the preparation of multienzyme-like nanoparticles, and TCCHA nanoparticles display great potential for enzyme catalysis-enhanced chemodynamic/photodynamic/antiangiogenic triple therapy against cancer.

Fasting-Mimicking Diet Facilitates Anti-tumor Therapeutic Effects by Nutrient-Sensitive Nanocomposites

Cancer cells support their uncontrolled proliferation primarily by regulating energy metabolism. Inhibiting tumor growth by blocking the supply of nutrients is an effective treatment strategy. Fasting-mimicking diet (FMD), as a low-calorie, low-protein, low-sugar, high-fat diet, can effectively reduce the nutrient supply to tumor cells. However, the significant biological barrier presented by the tumor microenvironment imposes greater demands and challenges for drug design. This study constructs the multifunctional nanocomposite ZnFe2O4@TiO2@CHC@Orl-FA (ZTCOF), which has great potential to overcome the aforementioned drawbacks. ZnFe2O4@TiO2 could produce 1O2 with ultrasound, and stimulate the Fenton-like conversion of endogenous H2O2 to ·OH, achieving a combined therapeutic effect of sonodynamic therapy (SDT) and chemodynamic therapy (CDT). Orl (Orlistat) and CHC (α-cyano-4-hydroxycinnamic acid) not only block tumor cell energy metabolism but also increase sensitivity to reactive oxygen species, enhancing the cytotoxic effect on tumor cells. Furthermore, combining the treatment strategies with FMD condition control can further inhibit cancer cell energy metabolism, achieving significant synergistic anti-tumor therapy. Both in vitro and in vivo experiments confirm that ZTCOF with SDT/CDT/starvation can achieve effective tumor suppression and destruction. This work provides theoretical and technical support for anti-tumor multimodal synergistic therapy.

Inhaled Macrophage Apoptotic Bodies-Engineered Microparticle Enabling Construction of Pro-Regenerative Microenvironment to Fight Hypoxic Lung Injury in Mice

Oxygen therapy cannot rescue local lung hypoxia in patients with severe respiratory failure. Here, an inhalable platform is reported for overcoming the aberrant hypoxia-induced immune changes and alveolar damage using camouflaged poly(lactic-co-glycolic) acid (PLGA) microparticles with macrophage apoptotic body membrane (cMAB). cMABs are preloaded with mitochondria-targeting superoxide dismutase/catalase nanocomplexes (NCs) and modified with pathology-responsive macrophage growth factor colony-stimulating factor (CSF) chains, which form a core-shell platform called C-cMAB/NC with efficient deposition in deeper alveoli and high affinity to alveolar epithelial cells (AECs) after CSF chains are cleaved by matrix metalloproteinase 9. Therefore, NCs can be effectively transported into mitochondria to inhibit inflammasome-mediated AECs damage in mouse models of hypoxic acute lung injury. Additionally, the at-site CSF release is sufficient to rescue circulating monocytes and macrophages and alter their phenotypes, maximizing synergetic effects of NCs on creating a pro-regenerative microenvironment that enables resolution of lung injury and inflammation. This inhalable platform may have applications to numerous inflammatory lung diseases.

Better together: nanoscale co-delivery systems of therapeutic agents for high-performance cancer therapy

Combination therapies can enhance the sensitivity of cancer to drugs, lower drug doses, and reduce side effects in cancer treatment. However, differences in the physicochemical properties and pharmacokinetics of different therapeutic agents limit their application. To avoid the above dilemma and achieve accurate control of the synergetic ratio, a nanoscale co-delivery system (NCDS) has emerged as a prospective tool for combined therapy in cancer treatment, which is increasingly being used to co-load different therapeutic agents. In this study, we have summarized the mechanisms of therapeutic agents in combination for cancer therapy, nanoscale carriers for co-delivery, drug-loading strategies, and controlled/targeted co-delivery systems, aiming to give a general picture of these powerful approaches for future NCDS research studies.

Nano-Engineering Strategies for Tumor-Specific Therapy

Nanodelivery systems (NDSs) provide promising prospects for decreasing drug doses, reducing side effects, and improving therapeutic effects. However, the bioapplications of NDSs are still compromised by their fast clearance, indiscriminate biodistribution, and limited tumor accumulation. Hence, engineering modification of NDSs aiming at promoting tumor-specific therapy and avoiding systemic toxicity is usually needed. An NDS integrating various functionalities, including flexible camouflage, specific biorecognition, and sensitive stimuli-responsiveness, into one sequence would be "smart" and highly effective. Herein, we systematically summarize the related principles, methods, and progress. At the end of the review, we predict the obstacles to precise nanoengineering and prospects for the future application of NDSs.

Aggregation-induced emission-active iridium (III)-based mitochondria-targeting nanoparticle for two-photon imaging-guided photodynamic therapy

The efficacy of imaging-guided photodynamic therapy (PDT) is compromised by the attenuation of fluorescence and decline in reactive oxygen species (ROS) generation efficiency in the physiological environment of conventional photosensitizers, limited near-infrared (NIR) absorption, and high systemic cytotoxicity. This paper presents the synthesis of two cyclometalated Ir (III) complexes (Ir-thpy and Ir-ppy) by using a triphenylamine derivative (DPTPA) as the primary ligand and their encapsulation into an amphiphilic phospholipid to form nanoparticles (NPs). These complexes exhibit aggregation-induced emission features and remarkably enhanced ROS generation compared to Chlorin e6 (Ce6). Moreover, Ir-thpy NPs possess the unique ability to selectively target mitochondria, leading to depolarization of the mitochondrial membrane potential and ultimately triggering apoptosis. Notably, Ir-thpy NPs exhibit exceptional photocytotoxicity even towards cisplatin-resistant A549/DDP tumor cells. In vivo two-photon imaging verified the robust tumor-targeting efficacy of Ir-thpy NPs. The in vivo results unequivocally demonstrate that Ir-thpy NPs exhibit excellent tumor ablation along with remarkable biocompatibility. This study presents a promising approach for the development of multifunctional Ir-NPs for two-photon imaging-guided PDT and provides novel insights for potential clinical applications in oncology.

Nanocarriers address intracellular barriers for efficient drug delivery, overcoming drug resistance, subcellular targeting and controlled release

The cellular barriers are major bottlenecks for bioactive compounds entering into cells to accomplish their biological functions, which limits their biomedical applications. Nanocarriers have demonstrated high potential and benefits for encapsulating bioactive compounds and efficiently delivering them into target cells by overcoming a cascade of intracellular barriers to achieve desirable therapeutic and diagnostic effects. In this review, we introduce the cellular barriers ahead of drug delivery and nanocarriers, as well as summarize recent advances and strategies of nanocarriers for increasing internalization with cells, promoting intracellular trafficking, overcoming drug resistance, targeting subcellular locations and controlled drug release. Lastly, the future perspectives of nanocarriers for intracellular drug delivery are discussed, which mainly focus on potential challenges and future directions. Our review presents an overview of intracellular drug delivery by nanocarriers, which may encourage the future development of nanocarriers for efficient and precision drug delivery into a wide range of cells and subcellular targets.

Tumor Microenvironment-Induced Drug Depository for Persistent Antitumor Chemotherapy and Immune Activation

Herein, a drug-loading nanosystem that can in situ form drug depository for persistent antitumor chemotherapy and immune regulation is designed and built. The system (DOX@MIL-LOX@AL) is fabricated by packaging alginate on the surface of Doxorubicin (DOX) and lactate oxidase (LOX) loaded MIL-101(Fe)-NH2 nanoparticle, which can easily aggregate in the tumor microenvironment through the cross-linking with intratumoral Ca2+. Benefiting from the tumor retention ability, the fast-formed drug depository will continuously release DOX and Fe ions through the ATP-triggered slow degradation, thus realizing persistent antitumor chemotherapy and immune regulation. Meanwhile, LOX in the non-aggregated nanoparticles is able to convert the lactic acid to H2O2, which will be subsequently decomposed into ·OH by Fe ions to further enhance the DOX-induced immunogenic death effect of tumor cells. Together, with the effective consumption of immunosuppressive lactic acid, long-term chemotherapy, and oxidation therapy, DOX@MIL-LOX@AL can execute high-performance antitumor chemotherapy and immune activation with only one subcutaneous administration.

Tumor Microenvironment Remodeling-Mediated Sequential Drug Delivery Potentiates Treatment Efficacy

Toll-like receptor 7/8 agonists, such as imidazoquinolines (IMDQs), are promising for the de novo priming of antitumor immunity. However, their systemic administration is severely limited due to the off-target toxicity. Here, this work describes a sequential drug delivery strategy. The formulation is composed of two sequential modules: a tumor microenvironment remodeling nanocarrier (poly(l-glutamic acid)-graft-methoxy poly(ethylene glycol)/combretastatin A4, termed CA4-NPs) and an immunotherapy nanocarrier (apcitide peptide-decorated poly(l-glutamic acid)-graft-IMDQ-N3 conjugate, termed apcitide-PLG-IMDQ-N3 ). CA4-NPs, as a vascular disrupting agent, are utilized to remodel the tumor microenvironment for enhancing tumor coagulation and hypoxia. Subsequently, the apcitide-PLG-IMDQ-N3 could identify and target tumor coagulation through the binding of surface apcitide peptide to the GPIIb-IIIa on activated platelets. Afterward, IMDQ is activated selectively through the conversion of "-N3 " to "-NH2 " in the presence of hypoxia. The biodistribution results confirm their high tumor uptake of activated IMDQ (22.66%ID/g). By augmenting the priming and immunologic memory of tumor-specific CD8+ T cells, 4T1 and CT26 tumors with a size of ≈500 mm3 are eradicated without recurrence in mouse models.

Boosting Sono-immunotherapy of Prostate Carcinoma through Amplifying Domino-Effect of Mitochondrial Oxidative Stress Using Biodegradable Cascade-Targeting Nanocomposites

Sono-immunotherapy faces challenges from poor immunogenicity and low response rate due to complex biological barriers. Herein, we prepared MCTH nanocomposites (NCs) consisting of disulfide bonds (S-S) doped mesoporous organosilica (MONs), Cu-modified protoporphyrin (CuPpIX), mitochondria-targeting triphenylphosphine (TPP), and CD44-targeting hyaluronic acid (HA). MCTH NCs efficiently accumulate at the tumor site due to the overexpressed CD44 receptors on the membrane of the cancer cells. Under the function of HAase and glutathione (GSH), MCTH degrades and exposes TPP to deliver CuPpIX to the mitochondrial site and induce a reactive oxygen species (ROS) burst in situ under ultrasound irradiations, thereby causing severe mitochondria dysfunction. This cascade-targeting ability of MCTH NCs not only reinforces oxidative stress in cancer cells but also amplifies immunogenic cell death (ICD) to stimulate the body's immune response and alleviate the tumor immunosuppressive microenvironment. These NCs significantly enhance the infiltration of immune cells into the tumor, particularly CD8+ T cells, for a powerful antitumor sono-immunotherapy. The proposed cascade-targeting strategy holds promise for strengthening sono-immunotherapy for prostate cancer treatment and overcoming the limitations of traditional immunotherapy.

Charge-Reversible Nanoparticles: Advanced Delivery Systems for Therapy and Diagnosis

The past two decades have witnessed a rapid progress in the development of surface charge-reversible nanoparticles (NPs) for drug delivery and diagnosis. These NPs are able to elegantly address the polycation dilemma. Converting their surface charge from negative/neutral to positive at the target site, they can substantially improve delivery of drugs and diagnostic agents. By specific stimuli like a shift in pH and redox potential, enzymes, or exogenous stimuli such as light or heat, charge reversal of NP surface can be achieved at the target site. The activated positive surface charge enhances the adhesion of NPs to target cells and facilitates cellular uptake, endosomal escape, and mitochondrial targeting. Because of these properties, the efficacy of incorporated drugs as well as the sensitivity of diagnostic agents can be essentially enhanced. Furthermore, charge-reversible NPs are shown to overcome the biofilm formed by pathogenic bacteria and to shuttle antibiotics directly to the cell membrane of these microorganisms. In this review, the up-to-date design of charge-reversible NPs and their emerging applications in drug delivery and diagnosis are highlighted.

Recent progress, perspectives, and issues of engineered PD-L1 regulation nano-system to better cure tumor: A review

Currently, immune checkpoint blockade (ICB) therapies that target the programmed cell death ligand-1 (PD-L1) have been used as revolutionary cancer treatments in the clinic. Apart from restoring the antitumor response of cytotoxic T cells by blocking the interaction between PD-L1 on tumor cells and programmed cell death-1 (PD-1) on T cells, PD-L1 proteins were also newly revealed to possess the capacity to accelerate DNA damage repair (DDR) and enhance tumor growth through multiple mechanisms, leading to the impaired efficacy of tumor therapies. Nevertheless, current free anti-PD-1/PD-L1 therapy still suffered from poor therapeutic outcomes in most solid tumors due to the non-selective tumor accumulation, ineludible severe cytotoxic effects, as well as the common occurrence of immune resistance. Recently, nanoparticles with efficient tumor-targeting capacity, tumor-responsive prosperity, and versatility for combination therapy were identified as new avenues for PD-L1 targeting cancer immunotherapies. In this review, we first summarized the multiple functions of PD-L1 protein in promoting tumor growth, accelerating DDR, as well as depressing immunotherapy efficacy. Following this, the effects and mechanisms of current clinically widespread tumor therapies on tumor PD-L1 expression were discussed. Then, we reviewed the recent advances in nanoparticles for anti-PD-L1 therapy via using PD-L1 antibodies, small interfering RNA (siRNA), microRNA (miRNA), clustered, regularly interspaced, short palindromic repeats (CRISPR), peptide, and small molecular drugs. At last, we discussed the challenges and perspectives to promote the clinical application of nanoparticles-based PD-L1-targeting therapy.

Challenges Coexist with Opportunities: Spatial Heterogeneity Expression of PD-L1 in Cancer Therapy

Cancer immunotherapy using anti-programmed death-ligand 1 (PD-L1) antibodies has been used in various clinical applications and achieved certain results. However, such limitations as autoimmunity, tumor hyperprogression, and overall low patient response rate impede its further clinical application. Mounting evidence has revealed that PD-L1 is not only present in tumor cell membrane but also in cytoplasm, exosome, or even nucleus. Among these, the dynamic and spatial heterogeneous expression of PD-L1 in tumors is mainly responsible for the unsatisfactory efficacy of PD-L1 antibodies. Hence, numerous studies focus on inhibiting or degrading PD-L1 to improve immune response, while a comprehensive understanding of the molecular mechanisms underlying spatial heterogeneity of PD-L1 can fundamentally transform the current status of PD-L1 antibodies in clinical development. Herein, the concept of spatial heterogeneous expression of PD-L1 is creatively introduced, encompassing the structure and biological functions of various kinds of PD-L1 (including mPD-L1, cPD-L1, nPD-L1, and exoPD-L1). Then an in-depth analysis of the regulatory mechanisms and potential therapeutic targets of PD-L1 is provided, seeking to offer a solid basis for future investigation. Moreover, the current status of agents is summarized, especially small molecular modulators development directed at these new targets, offering a novel perspective on potential PD-L1 therapeutics strategies.

Multistage Self-Assembled Nanomaterials for Cancer Immunotherapy

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

Enzymatically Activatable Polymers for Disease Diagnosis and Treatment

The irregular expression or activity of enzymes in the human body leads to various pathological disorders and can therefore be used as an intrinsic trigger for more precise identification of disease foci and controlled release of diagnostics and therapeutics, leading to improved diagnostic accuracy, sensitivity, and therapeutic efficacy while reducing systemic toxicity. Advanced synthesis strategies enable the preparation of polymers with enzymatically activatable skeletons or side chains, while understanding enzymatically responsive mechanisms promotes rational incorporation of activatable units and predictions of the release profile of diagnostics and therapeutics, ultimately leading to promising applications in disease diagnosis and treatment with superior biocompatibility and efficiency. By overcoming the challenges, new opportunities will emerge to inspire researchers to develop more efficient, safer, and clinically reliable enzymatically activatable polymeric carriers as well as prodrugs.

Synthesis of the pH-sensitive nanoparticles based on the acylhydrazone bonds conjugated doxorubicin and studies on their in vivo anti-tumor effects

The purpose of this study was to synthesize DHPD polymers through the conjugation of doxorubicin (DOX) molecules onto poly(ethylene glycol) (PEG) chains via acylhydrazone bonds, and to fabricate pH-responsive DHPD nanoparticles (NPs) for investigation of their biosecurity and in vivo anti-tumor activity. The morphology, size distribution, stability, pH-responsiveness, biosecurity, and in vivo anti-tumor effects of the DHPD NPs were evaluated. Characterization of the DHPD polymers using 1H NMR, FTIR, and Raman spectra confirmed their successful synthesis. The DHPD NPs exhibited a round morphology with an average diameter of 144.4 ± 1.7 nm and a polydispersity index (PDI) of 0.23 ± 0.02. Biosecurity studies indicated that the DHPD NPs were non-toxic to treated mice, and in vitro cell tests demonstrated their ability to be taken up by 4T1 cells. Under the acidic microenvironment of 4T1 cells, the acylhydrazone bonds were cleaved, resulting in increased DOX delivery to tumor cells and improved in vivo anti-tumor effects. Animal experiments confirmed that the DHPD NPs reduced DOX toxicity while enhancing its anti-tumor activity. Furthermore, results from the analysis of γ-interferon (INF-γ), tumor necrosis factor-α (TNF-α), epidermal growth factor (EGF), and vascular endothelial growth factor (VEGF) indicated that the DHPD NPs improved the anti-4T1 tumor effect of DOX, suggesting their potential application in the treatment of breast cancer.

Current research trends of nanomedicines

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

Tumor Abnormality-Oriented Nanomedicine Design

Anticancer nanomedicines have been proven effective in mitigating the side effects of chemotherapeutic drugs. However, challenges remain in augmenting their therapeutic efficacy. Nanomedicines responsive to the pathological abnormalities in the tumor microenvironment (TME) are expected to overcome the biological limitations of conventional nanomedicines, enhance the therapeutic efficacies, and further reduce the side effects. This Review aims to quantitate the various pathological abnormalities in the TME, which may serve as unique endogenous stimuli for the design of stimuli-responsive nanomedicines, and to provide a broad and objective perspective on the current understanding of stimuli-responsive nanomedicines for cancer treatment. We dissect the typical transport process and barriers of cancer drug delivery, highlight the key design principles of stimuli-responsive nanomedicines designed to tackle the series of barriers in the typical drug delivery process, and discuss the "all-into-one" and "one-for-all" strategies for integrating the needed properties for nanomedicines. Ultimately, we provide insight into the challenges and future perspectives toward the clinical translation of stimuli-responsive nanomedicines.

NIR-II fluorescence and PA imaging guided activation of STING pathway in photothermal therapy for boosting cancer immunotherapy by theranostic thermosensitive liposomes

Photothermal immunotherapy has shown great potential for efficient cancer treatment. However, the immunosuppressive tumor microenvironment forms a heavy barrier for photothermal-induced anti-tumor immunity by inhibiting dendritic cell (DC) maturation and cytotoxic T cell response. Moreover, the lack of reliable spatiotemporal imaging modalities makes photothermal immunotherapy difficult to guide tumor ablation and monitor therapeutic outcomes in real time. Herein, we designed a theranostic thermosensitive liposome (PLDD) as a versatile nanoplatform to boost the adaptive anti-tumor immunity of photothermal immunotherapy and to achieve multiple bioimaging modalities in a real-time manner. PLDD contains two major functional components: a multifunctional photothermal agent (DTTB) and an immune potentiator STING pathway agonist (DMXAA). Upon irradiation, the heat generated by DTTB induced the immunogenic cell death (ICD) of the tumor and dissociated the structure of thermosensitive liposome to release DMXAA, which ultimately activated the STING pathway and promoted the ICD-induced immune response by increasing DC cell maturation and T cell recruitment. Moreover, the DTTB in PLDD displayed excellent second near-infrared (NIR-II) fluorescence and photoacoustic (PA) dual-modal imaging, which provided omnibearing information on the tumor and guided the subsequent therapeutic operation. Therefore, this versatile PLDD with light-triggered promotion of anti-tumor immunity and multiple spatiotemporal imaging profiles holds great potential for the future development of cancer immunotherapy.

A dual-sensitive nanoparticle-mediated deepening synergistic therapy strategy involving DNA damage and ICD stimuli to treat triple-negative breast cancer

Triple-negative breast cancer (TNBC) is one of the most aggressive cancers with an immunosuppressive microenvironment, and achieving a satisfactory effect from monotherapies, such as chemotherapy, photodynamic therapy (PDT) or immunotherapy, remains difficult. To solve this puzzle, a deepening synergistic therapy strategy of DNA damage and immunogenic cell death (ICD) stimuli was proposed. We engineered a doxorubicin (DOX) and 4-(hydroxymethyl) phenylboronic acid pinacol ester (PBAP) prodrug polymer, and encapsulated chlorin e6 (Ce6) to obtain the hyaluronidase (HAase) and H2O2 dual-sensitive responsive nanoparticles (Ce6/HDP NPs). The NPs displayed efficient intratumoral accumulation and cellular internalization properties due to the active targeting of the hyaluronic acid (HA). The dual DNA damage of the chemotherapy and ROS production directly caused tumor cell apoptosis. The strong ICD stimuli, which were induced by ROS production and GSH depletion, generated an amplified immunogenicity to activate tumor immunotherapy in vivo. In this manner, the NPs could significantly inhibit primary tumor, abscopal tumor, pulmonary metastasis and recurrent tumor in a subcutaneous 4T1 tumor model, with effective biosafety. This study has provided a promising deepening synergistic therapy strategy against TNBC.

Nanoparticles with transformable physicochemical properties for overcoming biological barriers

In recent years, tremendous progress has been made in the development of nanomedicines for advanced therapeutics, yet their unsatisfactory targeting ability hinders the further application of nanomedicines. Nanomaterials undergo a series of processes, from intravenous injection to precise delivery at target sites. Each process faces different or even contradictory requirements for nanoparticles to pass through biological barriers. To overcome biological barriers, researchers have been developing nanomedicines with transformable physicochemical properties in recent years. Physicochemical transformability enables nanomedicines to responsively switch their physicochemical properties, including size, shape, surface charge, etc., thus enabling them to cross a series of biological barriers and achieve maximum delivery efficiency. In this review, we summarize recent developments in nanomedicines with transformable physicochemical properties. First, the biological dilemmas faced by nanomedicines are analyzed. Furthermore, the design and synthesis of nanomaterials with transformable physicochemical properties in terms of size, charge, and shape are summarized. Other switchable physicochemical parameters such as mobility, roughness and mechanical properties, which have been sought after most recently, are also discussed. Finally, the prospects and challenges for nanomedicines with transformable physicochemical properties are highlighted.

Metal-Phenolic Nanomedicines Regulate T-Cell Antitumor Function for Sono-Metabolic Cancer Therapy

Cancer cells outcompete tumor-infiltrating T lymphocytes (TILs) for glucose uptake, manipulating a glucose-deprived tumor microenvironment (TME) with high accumulation of lactate, which impairs CD8+ TIL effector function, however supports the immune suppression of regulatory T (Treg) cells. Aerobic glycolysis inhibition coupled with mitochondrial dysfunction in cancer cells may reprogram TME to destabilize Treg cells and, more importantly, facilitate CD8+ T cell activation and cytotoxic killing. Here, a sono-metabolic cancer therapy via hyaluronic acid (HA)-modified metal-phenolic nanomedicine (HPP-Ca@GSK) is proposed to accomplish the aforementioned goals. Abrogating lactate dehydrogenase A (LDHA) by delivering GSK2837808A (GSK, LDHA inhibitor) successfully suppresses aerobic glycolysis in cancer cells and creates high-glucose, low-lactate conditions, satisfying the glucose nutrition required by CD8+ TILs but destabilizing Treg cells. Meanwhile, depending on ultrasound-mediated oxidative stress, more than 3-fold of calcium (from HPP-Ca@GSK) is mitochondrion-overloaded, amplifying mitochondrial dysfunction and promoting the cancer cellular release of damage-associated molecular patterns for more CD8+ T cell activation and tumor infiltration. In vitro and in vivo studies demonstrate that HPP-Ca@GSK-based sono-metabolic treatment exhibits impressive anticancer activity. Cooperating with anticytotoxic T lymphocyte-associated protein-4 antibodies for enhanced Treg cell destabilization further improves therapeutic efficacy. These findings provide a metabolic intervention strategy for cancer immunotherapy.

Nanomedicine in cancer therapy

Cancer remains a highly lethal disease in the world. Currently, either conventional cancer therapies or modern immunotherapies are non-tumor-targeted therapeutic approaches that cannot accurately distinguish malignant cells from healthy ones, giving rise to multiple undesired side effects. Recent advances in nanotechnology, accompanied by our growing understanding of cancer biology and nano-bio interactions, have led to the development of a series of nanocarriers, which aim to improve the therapeutic efficacy while reducing off-target toxicity of the encapsulated anticancer agents through tumor tissue-, cell-, or organelle-specific targeting. However, the vast majority of nanocarriers do not possess hierarchical targeting capability, and their therapeutic indices are often compromised by either poor tumor accumulation, inefficient cellular internalization, or inaccurate subcellular localization. This Review outlines current and prospective strategies in the design of tumor tissue-, cell-, and organelle-targeted cancer nanomedicines, and highlights the latest progress in hierarchical targeting technologies that can dynamically integrate these three different stages of static tumor targeting to maximize therapeutic outcomes. Finally, we briefly discuss the current challenges and future opportunities for the clinical translation of cancer nanomedicines.

Glutathione Programmed Mitochondria Targeted Delivery of Lonidamine for Effective Against Triple Negative Breast Cancer

Introduction

Mitochondria are a significant target of lonidamine (LND). However, its limited solubility and inability to specifically target mitochondria, LND can lead to hepatic toxicity and has shown only modest anticancer activity. The objective of this study is to establish a glutathione programmed mitochondria targeted delivery of LND for the effective treatment of triple negative breast cancer (TNBC).

Methods

In this study, LND was encapsulated in poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) wrapped with mitochondria-targeting short-chain triphenylphosphonium-tocopherol polyethylene glycol succinate (TPP-TPGS, TPS) and tumor-targeting long-chain 1, 2-distearoyl-sn-glycero-3-phosphoethanolamine-S-S-polyethylene glycol-R6RGD (DSPE-S-S-PEG₂₀₀₀-R6RGD, DSSR), which were designated as LND-PLGA/TPS/DSSR NPs. The release behavior was evaluated, and cellular uptake, in vitro and in vivo antitumor activity of nanoparticles were investigated. The mechanism, including apoptosis of tumor cells and mitochondrial damage and respiratory rate detection, was also further investigated.

Results

LND-PLGA/TPS/DSSR NPs were successfully prepared, and characterization revealed that they are globular particles with smooth surfaces and an average diameter of about 250 nm. Long-chain DSSR in LND-PLGA/TPS/DSSR NPs prevented positively charged LND-PLGA/TPS NPs from being cleared by the reticuloendothelial system. Furthermore, LND release rate from NPs at pH 8.0 was significantly higher than that at pH 7.4 and 5.5, which demonstrated specific LND release in mitochondria and prevented LND leakage in cytoplasm and lysosome. NPs could locate in mitochondria, and the released LND triggered apoptosis of tumor cells by damaging mitochondria and releasing apoptosis-related proteins. In addition, in TNBC mice model, programmed mitochondria targeted NPs improved efficacy and reduced LND toxicity.

Conclusion

LND-PLGA/TPS/DSSR NPs may be a useful system and provide an effective approach for the treatment of TNBC.

A multifunctional 'golden cicada' nanoplatform breaks the thermoresistance barrier to launch cascade augmented synergistic effects of photothermal/gene therapy

BACKGROUND

Photothermal therapy (PTT) is taken as a promising strategy for cancer therapy, however, its applicability is hampered by cellular thermoresistance of heat shock response and insufficient accumulation of photothermal transduction agents in the tumor region. In consideration of those limitations, a multifunctional "Golden Cicada" nanoplatform (MGCN) with efficient gene delivery ability and excellent photothermal effects is constructed, overcoming the thermoresistance of tumor cells and improving the accumulation of indocyanine green (ICG).

RESULTS

Down-regulation of heat shock protein 70 (HSP70) makes tumor cells more susceptible to PTT, and a better therapeutic effect is achieved through such cascade augmented synergistic effects. MGCN has attractive features with prolonged circulation in blood, dual-targeting capability of CD44 and sialic acid (SA) receptors, and agile responsiveness of enzyme achieving size and charge double-variable transformation. It proves that, on the one hand, MGCN performs excellent capability for HSP70-shRNA delivery, resulting in breaking the cellular thermoresistance mechanism, on the other hand, ICG enriches in tumor site specifically and possesses a great thermal property to promoted PTT.

CONCLUSIONS

In short, MGCN breaks the protective mechanism of cellular heat stress response by downregulating the expression of HSP70 proteins and significantly augments synergistic effects of photothermal/gene therapy via cascade augmented synergistic effects.

Transformable nanodrugs for overcoming the biological barriers in the tumor environment during drug delivery

Drug delivery systems have been studied massively with explosive growth in the last few decades. However, challenges such as biological barriers are still obstructing the delivery efficiency of nanomedicines. Reports have shown that the physicochemical properties, such as the morphologies of nanodrugs, could highly affect their biodistribution and bioavailability. Therefore, transformable nanodrugs that take advantage of different sizes and shapes allow for overcoming multiple biological barriers, providing promising prospects for drug delivery. This review aims to present an overview of the most recent developments of transformable nanodrugs in this emerging field. First, the design principles and transformation mechanisms which serve as guidelines for smart nanodrugs are summarized. Afterward, their applications in overcoming biological barriers, including the bloodstream, intratumoral pressure, cellular membrane, endosomal wrapping, and nuclear membrane, are highlighted. Finally, discussions on the current developments and future perspectives of transformable nanodrugs are given.

A Cascade-Targeted Enzyme-Instructed Peptide Self-Assembly Strategy for Cancer Immunotherapy through Boosting Immunogenic Cell Death

Immunogenic cell death (ICD) approaches by encumbering mitochondrial functions provide great promise for the treatment of malignant tumors, but these kinds of ICD strategies are still in their infancy. Here, one multifunctional drug-loaded, cascade-targeted, and enzyme-instructed self-assembling peptide nanomedicine (Comp. 4) for ICD-based cancer therapy is constructed. Comp. 4 consists of 1) lonidamine (LND) that specifically interferes with mitochondrial functions; 2) a programmed death ligand 1 (PD-L1) binding peptide sequence (NTYYEDQG) and a mitochondria-specific motif (triphenylphosphonium, TPP) that can sequentially control the cell membrane and mitochondria targeting capacities, respectively; and 3) a -G^D F^D Fp^D Y- assembly core to in situ organize peptide assemblies responsive to alkaline phosphatase (ALP). Comp. 4 demonstrates noticeable structural and morphological transformations in the presence of ALP and produces peptide assemblies in mouse colon cancer cells (CT26) with high expressions of both ALP and PD-L1. Moreover, the presence of PD-L1- and mitochondria-specific motifs can assist Comp. 4 for effective endocytosis and endosomal escape, forming peptide assemblies and delivering LND into mitochondria. Consequently, Comp. 4 shows superior capacities to in vivo induce abundant mitochondrial oxidative stress, provoke robust ICD responses, and produce an immunogenic tumor microenvironment, successfully inhibiting CT26 tumor growth by eliciting a systemic ICD-based antitumor immunity.

Multiple stimulus-response berberine plus baicalin micelles with particle size-charge-release triple variable properties for breast cancer therapy

OBJECTIVE

The aim was to develop a nanoscale drug delivery system with enzyme responsive and acid sensitive particle size and intelligent degradation aiming to research the inhibitory effect on breast cancer.

SIGNIFICANCE

The delivery system addressed the problems of tissue targeting, cellular internalization, and slow drug release at the target site, which could improve the efficiency of drug delivery and provide a feasible therapeutic approach for breast cancer.

METHODS

The acid sensitive functional material DSPE-PEG₂₀₀₀-dyn-PEG-R9 was synthesized by Michael addition reaction. Then, the berberine plus baicalin intelligent micelles were prepared by thin-film hydration. Subsequently, we characterized the physical and chemical properties of berberine plus baicalin intelligent micelles, evaluated its anti-tumor effects in vivo and in vitro.

RESULTS

The target molecule was successfully synthesized, and the intelligent micelles showed excellent chemical and physical properties, delayed drug release and high encapsulation efficiency. In vitro and in vivo experiments also confirmed that the intelligent micelles could effectively target tumor sites, penetrate tumor tissues, enrich in tumor cells, inhibit tumor cell proliferation, inhibit tumor cell invasion and migration, and induce tumor cell apoptosis.

CONCLUSION

Berberine plus baicalin intelligent micelles have excellent anti-tumor effects and no toxicity to normal tissues, which provides a new potential drug delivery strategy for the treatment of breast cancer.

Drug-loaded microbubble delivery system to enhance PD-L1 blockade immunotherapy with remodeling immune microenvironment

BACKGROUND

Although programmed cell death protein 1 (PD-1)/ programmed cell death-ligand protein 1 (PD-L1) checkpoint blockade immunotherapy demonstrates great promise in cancer treatment, poor infiltration of T cells resulted from tumor immunosuppressive microenvironment (TIME) and insufficient accumulation of anti-PD-L1 (αPD-L1) in tumor sites diminish the immune response. Herein, we reported a drug-loaded microbubble delivery system to overcome these obstacles and enhance PD-L1 blockade immunotherapy.

METHODS

Docetaxel (DTX) and imiquimod (R837)-loaded microbubbles (RD@MBs) were synthesized via a typical rotary evaporation method combined with mechanical oscillation. The targeted release of drugs was achieved by using the directional "bursting" capability of ultrasound-targeted microbubble destruction (UTMD) technology. The antitumor immune response by RD@MBs combining αPD-L1 were evaluated on 4T1 and CT26 tumor models.

RESULTS

The dying tumor cells induced by DTX release tumor-associated antigens (TAAs), together with R837, promoted the activation, proliferation and recruitment of T cells. Besides, UTMD technology and DTX enhanced the accumulation of αPD-L1 in tumor sites. Moreover, RD@MBs remolded TIME, including the polarization of M2-phenotype tumor-associated macrophages (TAMs) to M1-phenotype, and reduction of myeloid-derived suppressor cells (MDSCs). The RD@MBs + αPD-L1 synergistic therapy not only effectively inhibited the growth of primary tumors, but also significantly inhibited the mimic distant tumors as well as lung metastases.

CONCLUSION

PD-L1 blockade immunotherapy was enhanced by RD@MBs delivery system.

Development of stimuli responsive polymeric nanomedicines modulating tumor microenvironment for improved cancer therapy

The complexity of the tumor microenvironment (TME) severely hinders the therapeutic effects of various cancer treatment modalities. The TME differs from normal tissues owing to the presence of hypoxia, low pH, and immune-suppressive characteristics. Modulation of the TME to reverse tumor growth equilibrium is considered an effective way to treat tumors. Recently, polymeric nanomedicines have been widely used in cancer therapy, because their synthesis can be controlled and they are highly modifiable, and have demonstrated great potential to remodel the TME. In this review, we outline the application of various stimuli responsive polymeric nanomedicines to modulate the TME, aiming to provide insights for the design of the next generation of polymeric nanomedicines and promote the development of polymeric nanomedicines for cancer therapy.

Polysaccharide-based nanocarriers for efficient transvascular drug delivery

Polysaccharide-based nanocarriers (PBNs) are the focus of extensive investigation because of their biocompatibility, low cost, wide availability, and chemical versatility, which allow a wide range of anticancer agents to be loaded within the nanocarriers. Similar to other nanocarriers, most PBNs are designed to extravasate out of tumor vessels, depending on the enhanced permeability and retention (EPR) effect. However, the EPR effect is compromised in some tumors due to the heterogeneity of tumor structures. Transvascular transport efficacy is decreased by complex blood vessels and condensed tumor stroma. The limited extravasation impedes efficient drug delivery into tumor parenchyma, and thus affects the subsequent tumor accumulation, which hinders the therapeutic effect of PBNs. Therefore, overcoming the biological barriers that restrict extravasation from tumor vessels is of great importance in PBN design. Many strategies have been developed to enhance the EPR effect that involve nanocarrier property regulation and tumor structure remodeling. Moreover, some researchers have proposed active transcytosis pathways that are complementary to the paracellular EPR effect to increase the transvascular extravasation efficiency of PBNs. In this review, we summarize the recent advances in the design of PBNs with enhanced transvascular transport to enable optimization of PBNs in the extravasation of the drug delivery process. We also discuss the obstacles and challenges that need to be addressed to clarify the transendothemial mechanism of PBNs and the potential interactions between extravasation and other drug delivery steps.

Mitochondrial dysfunction-targeted nanosystems for precise tumor therapeutics

Mitochondria play critical roles in the regulation of the proliferation and apoptosis of cancerous cells. Targeted induction of mitochondrial dysfunction in cancer cells by multifunctional nanosystems for cancer treatment has attracted increasing attention in the past few years. Numerous therapeutic nanosystems have been designed for precise tumor therapy by inducing mitochondrial dysfunction, including reducing adenosine triphosphate, breaking redox homeostasis, inhibiting glycolysis, regulating proteins, membrane potential depolarization, mtDNA damage, mitophagy dysregulation and so on. Understanding the mechanisms of mitochondrial dysfunction would be helpful for efficient treatment of diseases and accelerating the translation of these therapeutic strategies into the clinic. Then, various strategies to construct mitochondria-targeted nanosystems and induce mitochondrial dysfunction are summarized, and the recent research progress regarding precise tumor therapeutics is highlighted. Finally, the major challenges and an outlook in this rapidly developing field are discussed. This review is expected to inspire further development of novel mitochondrial dysfunction-based strategies for precise treatments of cancer and other human diseases.

Bioresponsive Immunotherapeutic Materials

The human immune system is an interaction network of biological processes, and its dysfunction is closely associated with a wide array of diseases, such as cancer, infectious diseases, tissue damage, and autoimmune diseases. Manipulation of the immune response network in a desired and controlled fashion has been regarded as a promising strategy for maximizing immunotherapeutic efficacy and minimizing side effects. Integration of "smart" bioresponsive materials with immunoactive agents including small molecules, biomacromolecules, and cells can achieve on-demand release of agents at targeted sites to reduce overdose-related toxicity and alleviate off-target effects. This review highlights the design principles of bioresponsive immunotherapeutic materials and discusses the critical roles of controlled release of immunoactive agents from bioresponsive materials in recruiting, housing, and manipulating immune cells for evoking desired immune responses. Challenges and future directions from the perspective of clinical translation are also discussed.

Targeting lactate metabolism for cancer immunotherapy - a matter of precision

Immune checkpoint inhibitors and adoptive T cell therapies have been valuable additions to the toolbox in the fight against cancer. These treatments have profoundly increased the number of patients with a realistic perspective toward a return to a cancer-free life. Yet, in a number of patients and tumor entities, cancer immunotherapies have been ineffective so far. In solid tumors, immune exclusion and the immunosuppressive tumor microenvironment represent substantial roadblocks to successful therapeutic outcomes. A major contributing factor to the depressed anti-tumor activity of immune cells in tumors is the harsh metabolic environment. Hypoxia, nutrient competition with tumor and stromal cells, and accumulating noxious waste products, including lactic acid, pose massive constraints to anti-tumor immune cells. Numerous strategies are being developed to exploit the metabolic vulnerabilities of tumor cells in the hope that these would also alleviate metabolism-inflicted immune suppression. While promising in principle, especially in combination with immunotherapies, these strategies need to be scrutinized for their effect on tumor-fighting immune cells, which share some of their key metabolic properties with tumor cells. Here, we provide an overview of strategies that seek to tackle lactate metabolism in tumor or immune cells to unleash anti-tumor immune responses, thereby opening therapeutic options for patients whose tumors are currently not treatable.

Hydrogel-guided strategies to stimulate an effective immune response for vaccine-based cancer immunotherapy

Cancer vaccines have attracted widespread interest in tumor therapy because of the potential to induce an effective antitumor immune response. However, many challenges including weak immunogenicity, off-target effects, and immunosuppressive microenvironments have prevented their broad clinical translation. To overcome these difficulties, effective delivery systems have been designed for cancer vaccines. As carriers in cancer vaccine delivery systems, hydrogels have gained substantial attention because they can encapsulate a variety of antigens/immunomodulators and protect them from degradation. This enables hydrogels to simultaneously reverse immunosuppression and stimulate the immune response. Meanwhile, the controlled release properties of hydrogels allow for precise temporal and spatial release of loads in situ to further enhance the immune response of cancer vaccines. Therefore, this review summarizes the classification of cancer vaccines, highlights the strategies of hydrogel-based cancer vaccines, and provides some insights into the future development of hydrogel-based cancer vaccines.

Engineering Multishelled Nanostructures Enables Stepwise Self-Degradability for Drug-Release Optimization

The balance between degradability and drug release kinetics is a major challenge for the development of drug delivery systems. Here we develop hierarchically structured nanoparticles comprising multiple noncontact silica shells using an amorphous calcium carbonate template. The system could be degraded in a sequential fashion on account of the molecularly engineered multishelled structures. The hydrolysis rate of drug-containing cores is inversely correlated with the nanoparticle concentration due to the shielding effect of the hierarchical nanostructure and could be exploited to regulate the release kinetics. Specifically, multishelled nanospheres show a low drug release rate with high doses that increases steadily as the concentration decreases due to continuous degradation, thus stabilizing the local drug concentration for effective tumor therapy. Moreover, the nanoparticles could be eventually degraded completely, which may reduce their health risks. This kind of hierarchically structured silica-based nanoparticle could serve as a sustainable drug depot and provides a new avenue for tumor treatment.

Opportunities and Challenges of Switchable Materials for Pharmaceutical Use

Switchable polymeric materials, which can respond to triggering signals through changes in their properties, have become a major research focus for parenteral controlled delivery systems. They may enable externally induced drug release or delivery that is adaptive to in vivo stimuli. Despite the promise of new functionalities using switchable materials, several of these concepts may need to face challenges associated with clinical use. Accordingly, this review provides an overview of various types of switchable polymers responsive to different types of stimuli and addresses opportunities and challenges that may arise from their application in biomedicine.

A combinational chemo-immune therapy using outer membrane vesicles for enhanced cancer therapy by RGD targeting

Cancer therapies are limited by poor drug penetration that impedes effective tumor treatment. This was overcome in the present study by loading the immune reaction inducing nanocarriers of the bacterial outer membrane vesicles (OMVs) and doxorubicin (DOX) into the natural immunity platform OMV via incubation. Drug accumulation at the tumor site was improved by using the targeting peptide 6-Mal- Arg-Gly-Asp (RGD) on the surface of OMVs to increase internalization via binding to cell surface integrin αvβ3. OMVs stimulate immune responses by reversing the immune-suppressive tumor microenvironment (TME) via decreasing TAM and Treg, increasing CD8+ T and M1, and promoting DC maturation. The combination of DOX and OMVs compensates for the shortcomings of monotherapy (e.g., chemotherapy and immunotherapy) and amplifies the therapeutic efficacy of cancer treatment, while aiding selection of novel nanocarriers and development of effective therapeutic regimens.

Precise Design Strategies of Nanotechnologies for Controlled Drug Delivery

Rapid advances in nanotechnologies are driving the revolution in controlled drug delivery. However, heterogeneous barriers, such as blood circulation and cellular barriers, prevent the drug from reaching the cellular target in complex physiologic environments. In this review, we discuss the precise design of nanotechnologies to enhance the efficacy, quality, and durability of drug delivery. For drug delivery in vivo, drugs loaded in nanoplatforms target particular sites in a spatial- and temporal-dependent manner. Advances in stimuli-responsive nanoparticles and carbon-based drug delivery platforms are summarized. For transdermal drug delivery systems, specific strategies including microneedles and hydrogel lead to a sustained release efficacy. Moreover, we highlight the current limitations of clinical translation and an incentive for the future development of nanotechnology-based drug delivery.

Tumor-targeted dual-starvation therapy based on redox-responsive micelle nanosystem with co-loaded LND and BPTES

The starvation therapy mediated by the lonidamine (LND) was limited by the low drug delivery efficiency, off-target effect and compensative glutamine metabolism. Herein, a hyaluronic acid (HA)-modified reduction-responsive micellar nanosystem co-loaded with glycolysis and glutamine metabolism inhibitor (LND and bis-2-(5-phenylacetmido-1,2,4-thiadiazol-2-yl)ethyl sulfide, BPTES) was constructed for tumor-targeted dual-starvation therapy. The in vitro and in vivo results collectively suggested that the fabricated nanosystem could effectively endocytosed by tumor cells via HA receptor-ligand recognition, and rapidly release starvation-inducers LND and BPTES in response to the GSH-rich intratumoral cytoplasm. Furthermore, the released LND and BPTES were capable of inducing glycolysis and glutamine metabolism suppression, and accompanied by significant mitochondrial damage, cell cycle arrest and tumor cells apoptosis, eventually devoting to the blockade of the energy and substance supply and tumor killing with high efficiency. In summary, HPPPH@L@B nanosystem significantly inhibited the compensatory glycolysis and glutamine metabolism via the dual-starvation therapy strategy, blocked the indispensable energy and substance supply of tumors, consequently leading to the desired tumor starvation and effective tumor killing with reliable biosafety.

The emergence of nanoporous materials in lung cancer therapy

Lung cancer is one of the most common cancers, affecting more than 2.1 million people across the globe every year. A very high occurrence and mortality rate of lung cancer have prompted active research in this area with both conventional and novel forms of therapies including the use of nanomaterials based drug delivery agents. Specifically, the unique physico-chemical and biological properties of porous nanomaterials have gained significant momentum as drug delivery agents for delivering a combination of drugs or merging diagnosis with targeted therapy for cancer treatment. This review focuses on the emergence of nano-porous materials for drug delivery in lung cancer. The review analyses the currently used nanoporous materials, including inorganic, organic and hybrid porous materials for delivering drugs for various types of therapies, including chemo, radio and phototherapy. It also analyses the selected research on stimuli-responsive nanoporous materials for drug delivery in lung cancer before summarizing the various findings and projecting the future of emerging trends. This review provides a strong foundation for the current status of the research on nanoporous materials, their limitations and the potential for improving their design to overcome the unique challenges of delivering drugs for the treatment of lung cancer.

Dynamic Effects of Endo-Exogenous Stimulations on Enzyme-Activatable Polymeric Nanosystems with Photo-Sono-Chemo Synergy

Activatable polymeric nanosystems have attracted great interest, and their interactions with endo-exogenous stimulations are highly vital for therapeutic efficacy, which urgently needs systematic study. Herein we focus on systematically investigating these interactions on an enzyme-nanosystem model, the tumor-overexpressed hyaluronidase (HAase) and the doxorubicin-loaded hyaluronic-acid-porphyrin nanoassemblies (DOX@HPNAs), to augment photo-sono-chemo therapies. The HAase degrades the HPNAs in acidic solution at a higher rate than that in neutral solution, which leads to structure disassembly at the nano level, chain cleavage at the molecular level, and strong radiative recovery at the energy level. Upon excitation with light and ultrasound, the enzymatically degraded sample produces ∼2.5 times more singlet oxygen than the HPNAs because of the absence of aggregation-induced quenching and ¹O₂ migration limitation. The nanosystem can be activated by trimodal stimulations (acidity, ultrasound, and HAase), exerting the controllable release behavior and high release content. Moreover, the nanosystem exhibits synergistic effects among efficient photodynamic therapy, high tissue-penetrating sonodynamic therapy, and lasting chemotherapy, which induces significant necrosis and apoptosis of cancer cells. With high compatibility, tumor-targeting ability, and fluorescent-imaging-guided capability, the nanosystem achieves the highest inhibition rate of malignant tumors than the single or dual-modal therapies. Thus, the enzyme-activatable nanosystem enables the therapeutic synergy and also provides insights to develop other polymeric nanosystems.

An Acid-Sensitive Nanofiber Conjugate Based on a Short Aromatic Peptide for Targeted Delivery of Doxorubicin in Liver Cancer

Purpose

This study aimed to construct a DOX conjugate with liver tumor targeting and acid sensitivity based on a short aromatic peptide FFYEE, which could amplify the tumor inhibition efficacy of DOX and alleviate tissue toxicity.

Methods

A novel DOX-peptide conjugate, D-gal-FFYEE-hyd-DOX, was constructed by linking DOX to the side chain of FFYEE with acid-sensitive hydrazone bond and by modifying the C-terminal of peptide with α-D-galactosamine (D-gal) as targeting ligand. The structure of D-gal-FFYEE-hyd-DOX was characterized by mass spectrometry, infrared spectroscopy (IR), and UV-Vis spectroscopy (UV-Vis). The assembly characteristics of pentapeptide FFYEE and D-gal-FFYEE-hyd-DOX were observed by transmission electron microscope (TEM). In vitro drug release, cytotoxicity, endocytosis, in vivo antitumor experiment and histopathology analysis were investigated.

Results

Peptide FFYEE endowed the D-gal-FFYEE-hyd-DOX with self-assembly performance and improved biocompatibility. D-gal-FFYEE-hyd-DOX can self-assemble into nanofibers with a diameter of ~ 40 nm in neutral aqueous solution and significantly reduced the cytotoxicity of free DOX to L02 cells. In vitro drug release results showed that D-gal-FFYEE-hyd-DOX had acid sensitivity and controlled release characteristics. The cytotoxicity and endocytosis investigations confirmed that D-gal-FFYEE-hyd-DOX enhanced the cellular uptake of DOX and inhibition effect on HepG2 cells. In vivo antitumor experiment indicated that D-gal-FFYEE-hyd-DOX could significantly inhibit the growth of liver tumor in mice and reduce the side effects of DOX.

Conclusion

The conjugate D-gal-FFYEE-hyd-DOX with liver tumor targeting and acid sensitivity has the characteristics of strong tumor inhibition and low toxicity, hinting the great clinical application potential for targeted delivery of DOX in cancer treatment.

A targeted nanomodulator capable of manipulating tumor microenvironment against metastasis

Recently, lactate has been considered as an alternative direct energy substance to glucose for tumor proliferation and metastasis. Meanwhile, mitochondria, as important energy-supplying organelles, are also closely related to tumor progression. Consequently, a new research direction for lactate comprises lactate deprivation coupled with mitochondria-targeted phototherapy to achieve a safer and more effective strategy against tumor metastasis. Herein, linoleic acid-conjugated hyaluronic acid (HL), disulfide bond-rich nanovehicle (mesoporous silica, MOS), mitochondria-targeted IR780 (M780) and lactate oxidase (LOD) are rationally designed as a specific-targeting metabolism nanomodulator (HL/MOS@M780&LOD NPs), fulfilling the task of simultaneous depriving cells of lactate and damaging mitochondria to prevent tumor metastasis. Interestingly, M780-mediated photodynamic therapy (PDT) and LOD-mediated starvation therapy can effectively exacerbate the hypoxia state of tumor cells, thereby increasing the free iron levels to activate ferroptosis. On one hand, pyruvic acid and H₂O₂ generated by LOD-mediated lactate metabolism can provide powerful conditions for iron-catalyzed ferroptosis. On the other, the depleted GSH and increased reactive oxygen species (ROS) can oxidize linoleic acid into lipid peroxides (LPO) to further augment ferroptosis. The designed nanomodulator therefore shows great promise for fighting tumor metastasis by manipulating energy metabolism and the hypoxia microenvironment.

Inhalable Biomimetic Protein Corona-Mediated Nanoreactor for Self-Amplified Lung Adenocarcinoma Ferroptosis Therapy

Ferroptosis therapy by catalyzing the Fenton reaction has emerged as a promising tumor elimination strategy for lung adenocarcinoma (ADC). However, the unsatisfactory Fenton reaction efficiency, strong intracellular antioxidant system, and insufficient lung drug accumulation limits the ferroptosis therapeutic effect. To address these issues, an inhalable nanoreactor was proposed by spontaneously adsorbing biomimetic protein corona (PC) composed of matrix metalloproteinase 2 responsive gelatin and glutamate (Glu) on the surface of cationic nanostructured lipid carriers (NLC) core loaded with ferrocene (Fc) and fluvastatin. The prepared Fc-NLC(F)@PC could be nebulized into lung lesions with 2.6 times higher drug accumulation and boost lipid peroxide production by 3.2 times to enhance ferroptosis therapy. Mechanically, fluvastatin was proved to inhibit monocarboxylic acid transporter 4 mediated lactate efflux, inducing tumor acidosis to boost Fc-catalyzing reactive oxygen species production, while the extracellular elevating Glu concentration was found to inhibit xCT (system X_c^-) functions and further collapse the tumor antioxidant system by glutathione synthesis suppression. Mitochondrial dysfunction and cell membrane damage were involved in the nanoreactor-driven ferroptotic cell death process. The enhanced antitumor effects by combination of tumor acidosis and antioxidant system collapse were confirmed in an orthotopic lung ADC tumor model. Overall, the proposed nanoreactor highlights the pulmonary delivery approach for local lung ADC treatment and underscores the great potential of ferroptosis therapy.