Enzyme-triggered size shrink and laser-enhanced NO release nanoparticles for deep tumor penetration and combination therapy

Low-dose X-ray stimulated NO-releasing nanocomposites for closed-loop dual-mode cancer therapy

X-ray-excited photodynamic therapy (X-PDT) employs X-rays as an energy source, overcoming the light penetration limitations of traditional photodynamic therapy (PDT) but is constrained by high-energy radiation and the hypoxic tumor microenvironment. Low-dose X-ray-excited photodynamic therapy and reduction of mitochondrial oxygen consumption can serve as significant breakthroughs in overcoming these barriers. In this study, NaLuF4:Tb/Gd (15%/5%)@NaYF4 (ScNP) nanoparticles adsorbing the photosensitizer MC540 and loaded with α-(nitrate ester) acid (NEAA) were prepared as low X-ray dose triggered nano-scintillators. The final product obtained was NaLuF4:Tb/Gd (15%/5%)@NaYF4@mSiO2@MC540@NEAA (ScNP-MS@MC540@NEAA) nanocomposites, which exhibited intense green luminescence. X-PDT generates cytotoxic reactive oxygen species (ROS) with minimal ionizing radiation damage. Simultaneously, NEAA reacts with glutathione (GSH) to generate nitric oxide (NO) for gaseous treatment of the damaged mitochondrial respiratory chain to reduce oxygen consumption and alleviate hypoxia, enhancing the X-PDT efficacy and realizing a closed-loop treatment. The superoxide ions (˙O2-) can rapidly react with NO produced to form the highly cytotoxic reactive nitrogen species (RNS) peroxynitrite anion (ONOO-), which exhibits higher cytotoxicity compared to ROS. Furthermore, GSH scavenges toxic ROS and maintains the physiological function of tumor cells. It can induce cancer cell overoxidation and nitrosative stress. This work describes a low-dose X-ray-triggered X-PDT system with total radiation of 50 mGy, which involves GSH consumption, self-supplied NO, mitochondrial damage alleviation, and hypoxia relief to generate ROS and RNS, forming a closed-loop anti-hypoxia dual-mode system with synergistically enhanced anti-tumor effects, without significant biological side effects. It provides a promising platform for deep-seated tumor X-PDT with considerable application prospects.

NIR-triggered arsenic-loaded layered double hydroxide-based films for localized thermal synergistic chemotherapy

Portal vein tumor thrombus (PVTT) formed by cancer cell invasion is a major cause of high mortality in hepatocellular carcinoma (HCC), and the formation of thrombus will be accelerated by bacterial colonization on the surface of the implant after surgery. In this work, Polypyrrole-coated arsenic-loaded layered double hydroxide films were in situ constructed on the nickel-titanium alloy for the efficient killing of tumour cells by thermo-therapeutic synergistic chemotherapy. The good near-infrared photothermal conversion ability of polypyrrole enables the sample surface temperature to be raised to about 51 °C at a low photothermal power (0.5 w/cm2), while the elevated temperature could further accelerate the release of drug arsenic. In addition, when NIR light is not applied, the polypyrrole coating also cleverly acts as a "barrier layer" to reduce the natural release of arsenic in normal tissues to avoid toxicity issues. In vivo and in vitro experiments have demonstrated that the platform exhibits excellent antitumor and antibacterial abilities. In contrast to the systemic toxicity issues associated with systemic circulation of nanotherapeutic drugs, this in situ functional film is expected to be used in localised interventions for precise drug delivery, and is also more suitable for surgical treatment scenarios in PVTT surgeries.

Augmentation of the EPR effect by mild hyperthermia to improve nanoparticle delivery to the tumor

The clinical translation of the nanoparticle (NP)-based anticancer therapies is still unsatisfactory due to the heterogeneity of the enhanced permeability and retention (EPR) effect. Despite the promising preclinical outcome of the pharmacological EPR enhancers, their systemic toxicity can limit their clinical application. Hyperthermia (HT) presents an efficient tool to augment the EPR by improving tumor blood flow (TBF) and vascular permeability, lowering interstitial fluid pressure (IFP), and disrupting the structure of the extracellular matrix (ECM). Furthermore, the HT-triggered intravascular release approach can overcome the EPR effect. In contrast to pharmacological approaches, HT is safe and can be focused to cancer tissues. Moreover, HT conveys direct anti-cancer effects, which improve the efficacy of the anti-cancer agents encapsulated in NPs. However, the clinical application of HT is challenging due to the heterogeneous distribution of temperature within the tumor, the length of the treatment and the complexity of monitoring.

Hydroxyethyl starch-based self-reinforced nanomedicine inhibits both glutathione and thioredoxin antioxidant pathways to boost reactive oxygen species-powered immunotherapy

The adaptive antioxidant systems of tumor cells, predominantly glutathione (GSH) and thioredoxin (TRX) networks, severely impair photodynamic therapy (PDT) potency and anti-tumor immune responses. Here, a multistage redox homeostasis nanodisruptor (Phy@HES-IR), integrated by hydroxyethyl starch (HES)-new indocyanine green (IR820) conjugates with physcion (Phy), an inhibitor of the pentose phosphate pathway (PPP), is rationally designed to achieve PDT primed cancer immunotherapy. In this nanodisruptor, Phy effectively depletes intracellular GSH of tumor cells by inhibiting 6-phosphogluconate dehydrogenase (6PGD) activity. Concurrently, it is observed for the first time that the modified IR820-NH2 molecule not only exerts PDT action but also interferes with TRX antioxidant pathway by inhibiting thioredoxin oxidase (TRXR) activity. The simultaneous weakening of two major antioxidant pathways of tumor cells is favorable to maximize the PDT efficacy induced by HES-IR conjugates. By virtue of the excellent protecting ability of the plasma expander HES, Phy@HES-IR can remain stable in the blood circulation and efficiently enrich in the tumor region. Consequently, PDT and metabolic modulation synergistically induced immunogenic cell death, which not only suppressed primary tumors but also stimulated potent anti-tumor immunity to inhibit the growth of distant tumors in 4T1 tumor-bearing mice.

Lipo/TK-CDN/TPP/Y6 nanoparticles inhibit cutaneous melanoma formation

Stimulation of the innate immune stimulator of interferon genes (STING) pathway has been shown to boost anti-tumour immunity. Nevertheless, the systemic delivery of STING agonists to the tumour presents challenges. Therefore, we designed a cyclic dinucleotide (CDN)-based drug delivery system (DDS) combined photothermal therapy (PTT)/photodynamic therapy (PDT)/immunotherapy for cutaneous melanoma. We coencapsulated a reactive oxygen species (ROS)-responsive prodrug thioketone-linked CDN (TK-CDN), and photoresponsive agents chlorin E6 (Y6) within mitochondria-targeting reagent triphenylphosphonium (TPP)-modified liposomes (Lipo/TK-CDN/TPP/Y6). Lipo/TK-CDN/TPP/Y6 exhibited a photothermal effect similar to Y6, along with a superior cellular uptake rate. Upon endocytosis by B16F10 cells, Lipo/TK-CDN/TPP/Y6 generated large amounts of ROS under laser irradiation for PDT. Mice bearing B16F10 tumours were intravenously injected with Lipo/TK-CDN/TPP/Y6 and exposed to irradiation, resulting in a substantial inhibition of tumour growth. Exploration of the mechanism of anti-tumour action showed that Lipo/TK-CDN/TPP/Y6 had a stronger stimulation of STING activation and anti-tumour immune cell infiltration compared to other groups. Hence, the Lipo/TK-CDN/TPP/Y6 nanoparticles offer great potential as a DDS for targeted and on-demand drug release at tumour sites. These nanoparticles exhibit promise as a candidate for precise and controllable combination therapy in the treatment of tumours.

pH-responsive drug-loaded peptides enhance drug accumulation and promote apoptosis in tumor cells

The efficacy of chemotherapeutic drugs in tumor treatment is limited by their toxicity and side effects due to their inability to selectively accumulate in tumor tissue. In addition, chemotherapeutic agents are easily pumped out of tumor cells, resulting in their inadequate accumulation. To overcome these challenges, a drug delivery system utilizing the amphiphilic peptide Pep1 was designed. Pep1 can self-assemble into spherical nanoparticles (PL/Pep1) and encapsulate paclitaxel (PTX) and lapatinib (LAP). PL/Pep1 transformed into nanofibers in an acidic environment, resulting in longer drug retention and higher drug concentrations within tumor cells. Ultimately, PL/Pep1 inhibited tumor angiogenesis and enhanced tumor cell apoptosis. The use of shape-changing peptides as drug carriers to enhance cancer cell apoptosis is promising.

Adjuvant Novel Nanocarrier-Based Targeted Therapy for Lung Cancer

Lung cancer has the lowest survival rate due to its late-stage diagnosis, poor prognosis, and intra-tumoral heterogeneity. These factors decrease the effectiveness of treatment. They release chemokines and cytokines from the tumor microenvironment (TME). To improve the effectiveness of treatment, researchers emphasize personalized adjuvant therapies along with conventional ones. Targeted chemotherapeutic drug delivery systems and specific pathway-blocking agents using nanocarriers are a few of them. This study explored the nanocarrier roles and strategies to improve the treatment profile's effectiveness by striving for TME. A biofunctionalized nanocarrier stimulates biosystem interaction, cellular uptake, immune system escape, and vascular changes for penetration into the TME. Inorganic metal compounds scavenge reactive oxygen species (ROS) through their photothermal effect. Stroma, hypoxia, pH, and immunity-modulating agents conjugated or modified nanocarriers co-administered with pathway-blocking or condition-modulating agents can regulate extracellular matrix (ECM), Cancer-associated fibroblasts (CAF),Tyro3, Axl, and Mertk receptors (TAM) regulation, regulatory T-cell (Treg) inhibition, and myeloid-derived suppressor cells (MDSC) inhibition. Again, biomimetic conjugation or the surface modification of nanocarriers using ligands can enhance active targeting efficacy by bypassing the TME. A carrier system with biofunctionalized inorganic metal compounds and organic compound complex-loaded drugs is convenient for NSCLC-targeted therapy.

Dual-responsive supramolecular photodynamic nanomedicine with activatable immunomodulation for enhanced antitumor therapy

A major challenge facing photodynamic therapy (PDT) is that the activity of the immune-induced infiltrating CD8+ T cells is subject to the regulatory T lymphocytes (Tregs), leaving the tumor at risk of recurrence and metastasis after the initial ablation. To augment the antitumor response and reprogram the immunosuppressive tumor microenvironment (TME), a supramolecular photodynamic nanoparticle (DACss) is constructed by the host-guest interaction between demethylcantharidin-conjugated β-cyclodextrin (DMC-CD) and amantadine-terminated disulfide-conjugated FFVLGGGC peptide with chlorin e6 decoration (Ad-ss-pep-Ce6) to achieve intelligent delivery of photosensitizer and immunomodulator for breast cancer treatment. The acid-labile β-carboxamide bond of DMC-CD is hydrolyzed in response to the acidic TME, resulting in the localized release of DMC and subsequent inhibition of Tregs. The guest molecule Ad-ss-pep-Ce6 can be cleaved by a high level of intracellular GSH, reducing photosensitizer toxicity and increasing photosensitizer retention in the tumor. With a significant increase in the CTL/Treg ratio, the combination of Ce6-based PDT and DMC-mediated immunomodulation adequately achieved spatiotemporal regulation and remodeling of the TME, as well as improved primary tumor and in situ lung metastasis suppression with the aid of PD-1 antibody.

Enhancing drug penetration in solid tumors via nanomedicine: Evaluation models, strategies and perspectives

Effective tumor treatment depends on optimizing drug penetration and accumulation in tumor tissue while minimizing systemic toxicity. Nanomedicine has emerged as a key solution that addresses the rapid clearance of free drugs, but achieving deep drug penetration into solid tumors remains elusive. This review discusses various strategies to enhance drug penetration, including manipulation of the tumor microenvironment, exploitation of both external and internal stimuli, pioneering nanocarrier surface engineering, and development of innovative tactics for active tumor penetration. One outstanding strategy is organelle-affinitive transfer, which exploits the unique properties of specific tumor cell organelles and heralds a potentially transformative approach to active transcellular transfer for deep tumor penetration. Rigorous models are essential to evaluate the efficacy of these strategies. The patient-derived xenograft (PDX) model is gaining traction as a bridge between laboratory discovery and clinical application. However, the journey from bench to bedside for nanomedicines is fraught with challenges. Future efforts should prioritize deepening our understanding of nanoparticle-tumor interactions, re-evaluating the EPR effect, and exploring novel nanoparticle transport mechanisms.

A strategy for mechanically integrating robust hydrogel-tissue hybrid to promote the anti-calcification and endothelialization of bioprosthetic heart valve

Bioprosthetic heart valve (BHV) replacement has been the predominant treatment for severe heart valve diseases over decades. Most clinically available BHVs are crosslinked by glutaraldehyde (GLUT), while the high toxicity of residual GLUT could initiate calcification, severe thrombosis, and delayed endothelialization. Here, we construed a mechanically integrating robust hydrogel-tissue hybrid to improve the performance of BHVs. In particular, recombinant humanized collagen type III (rhCOLIII), which was precisely customized with anti-coagulant and pro-endothelialization bioactivity, was first incorporated into the polyvinyl alcohol (PVA)-based hydrogel via hydrogen bond interactions. Then, tannic acid was introduced to enhance the mechanical performance of PVA-based hydrogel and interfacial bonding between the hydrogel layer and bio-derived tissue due to the strong affinity for a wide range of substrates. In vitro and in vivo experimental results confirmed that the GLUT-crosslinked BHVs modified by the robust PVA-based hydrogel embedded rhCOLIII and TA possessed long-term anti-coagulant, accelerated endothelialization, mild inflammatory response and anti-calcification properties. Therefore, our mechanically integrating robust hydrogel-tissue hybrid strategy showed the potential to enhance the service function and prolong the service life of the BHVs after implantation.

Current trends in gas-synergized phototherapy for improved antitumor theranostics

Phototherapy, such as photothermal therapy (PTT) and photodynamic therapy (PDT), has been considered an elegant solution to eradicate tumors due to its minimal invasiveness and low systemic toxicity. Nevertheless, it is still challenging for phototherapy to achieve ideal outcomes and clinical translation due to its inherent drawbacks. Owing to the unique biological functions, diverse gases have attracted growing attention in combining with phototherapy to achieve super-additive therapeutic effects. Specifically, gases such as nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S) have been proven to kill tumor cells by inducing mitochondrial damage in synergy with phototherapy. Additionally, several gases not only enhance the thermal damage in PTT and the reactive oxygen species (ROS) production in PDT but also improve the tumor accumulation of photoactive agents. The inflammatory responses triggered by hyperthermia in PTT are also suppressed by the combination of gases. Herein, we comprehensively review the latest studies on gas-synergized phototherapy for cancer therapy, including (1) synergistic mechanisms of combining gases with phototherapy; (2) design of nanoplatforms for gas-synergized phototherapy; (3) multimodal therapy based on gas-synergized phototherapy; (4) imaging-guided gas-synergized phototherapy. Finally, the current challenges and future opportunities of gas-synergized phototherapy for tumor treatment are discussed. STATEMENT OF SIGNIFICANCE: 1. The novelty and significance of the work with respect to the existing literature. (1) Strategies to design nanoplatforms for gas-synergized anti-tumor phototherapy have been summarized for the first time. Meanwhile, the integration of various imaging technologies and therapy modalities which endow these nanoplatforms with advanced theranostic capabilities has been summarized. (2) The mechanisms by which gases synergize with phototherapy to eradicate tumors are innovatively and comprehensively summarized. 2. The scientific impact and interest. This review elaborates current trends in gas-synergized anti-tumor phototherapy, with special emphases on synergistic anti-tumor mechanisms and rational design of therapeutic nanoplatforms to achieve this synergistic therapy. It aims to provide valuable guidance for researchers in this field.

Liposomal Nano-Based Drug Delivery Systems for Breast Cancer Therapy: Recent Advances and Progresses

Breast cancer is a highly prevalent disease on a global scale, with a 30% incidence rate among women and a 14% mortality rate. Developing countries bear a disproportionate share of the disease burden, while countries with greater technological advancements exhibit a higher incidence. A mere 7% of women under the age of 40 are diagnosed with breast cancer, and the prevalence of this ailment is significantly diminished among those aged 35 and younger. Chemotherapy, radiation therapy, and surgical intervention comprise the treatment protocol. However, the ongoing quest for a definitive cure for breast cancer continues. The propensity for cancer stem cells to metastasize and resistance to treatment constitute their Achilles' heel. The advancement of drug delivery techniques that target cancer cells specifically holds significant promise in terms of facilitating timely detection and effective intervention. Novel approaches to pharmaceutical delivery, including nanostructures and liposomes, may bring about substantial changes in the way breast cancer is managed. These systems offer a multitude of advantages, such as heightened bioavailability, enhanced solubility, targeted tumor destruction, and diminished adverse effects. The application of nano-drug delivery systems to administer anti-breast cancer medications is a significant subject of research. This article delves into the domain of breast cancer, conventional treatment methods, the incorporation of nanotechnology into managerial tactics, and strategic approaches aimed at tackling the disease at its core.

All-in-one HN@Cu-MOF nanoparticles with enhanced reactive oxygen species generation and GSH depletion for effective tumor treatment

Non-invasive cancer therapies, especially those based on reactive oxygen species, including photodynamic therapy (PDT), have gained much interest. As emerging photodynamic nanocarriers, metal-organic frameworks (MOFs) based on porphyrin can release reactive oxygen species (ROS) to destroy cancer cells. However, due to the inefficient production of ROS by photosensitizers and the over-expression of glutathione (GSH) in the tumor microenvironment (TME), their therapeutic effect is not satisfactory. Therefore, herein, we developed a multi-functional nanoparticle, HN@Cu-MOF, to enhance the efficacy of PDT. We combined chemical dynamic therapy (CDT) and nitric oxide (NO) therapy by initiating sensitization to PDT and cell apoptosis in the treatment of tumors. The Cu2+-doped MOF reacted with GSH to form Cu+, exhibiting a strong CDT ability to generate hydroxyl radicals (˙OH). The Cu-MOF was coated with HN, which is hyaluronic acid (HA) modified by a nitric oxide donor. HN can target tumor cells over-expressing the CD44 receptor and consume GSH in the cells to release NO. Both cell experiments and in vivo experiments showed an excellent tumor inhibitory effect upon the treatment. Overall, the HN@Cu-MOF nanoparticle-integrated NO gas therapy and CDT with PDT led to a significant enhancement in GSH consumption and a remarkable elevation in ROS production.

Stimuli-sensitive nano-drug delivery with programmable size changes to enhance accumulation of therapeutic agents in tumors

Nano-based drug delivery systems hold significant promise for cancer therapies. Presently, the poor accumulation of drug-carrying nanoparticles in tumors has limited their success. In this study, based on a combination of the paradigms of intravascular and extravascular drug release, an efficient nanosized drug delivery system with programmable size changes is introduced. Drug-loaded smaller nanoparticles (secondary nanoparticles), which are loaded inside larger nanoparticles (primary nanoparticles), are released within the microvascular network due to temperature field resulting from focused ultrasound. This leads to the scale of the drug delivery system decreasing by 7.5 to 150 times. Subsequently, smaller nanoparticles enter the tissue at high transvascular rates and achieve higher accumulation, leading to higher penetration depths. In response to the acidic pH of tumor microenvironment (according to the distribution of oxygen), they begin to release the drug doxorubicin at very slow rates (i.e., sustained release). To predict the performance and distribution of therapeutic agents, a semi-realistic microvascular network is first generated based on a sprouting angiogenesis model and the transport of therapeutic agents is then investigated based on a developed multi-compartment model. The results show that reducing the size of the primary and secondary nanoparticles can lead to higher cell death rate. In addition, tumor growth can be inhibited for a longer time by enhancing the bioavailability of the drug in the extracellular space. The proposed drug delivery system can be very promising in clinical applications. Furthermore, the proposed mathematical model is applicable to broader applications to predict the performance of drug delivery systems.

UCNPs-based nanoreactors with ultraviolet radiation-induced effect for enhanced ferroptosis therapy of tumor

The limitations of light source limit the clinical application of optical therapy technology. How to improve the application efficiency of radiant light has become the focus of researchers. Here, we synthesize a kind of UCNPs@PVP-GOx-PpIX-Fe3+ (UPGPF) nanoreactors with rare earth upconversion nanoparticles (UCNPs) as the substrate for the enhancement of ferroptosis effect by the synergistic starvation/photodynamic therapies. Firstly, glucose oxidase (GOx) and Fe3+ loaded in UPGPF nanoreactors are used to directly face the problems of insufficient H2O2 level in tumor tissue and low Fenton reaction efficiency. Further, UCNPs can absorb NIR light at 980 nm and convert low-energy photons into high-energy photons, thereby cleverly generating ultraviolet (UV) radiation induction in vivo, which can produce a synergistic effect of enhancing iron death. The in vivo experimental results of breast cancer model mice show that the UPGPF nanoreactors have significant anticancer effect and good biosafety. With the help of the optical conversion characteristics of UCNPs, this kind of treatment idea of building a UV radiation-induced microplatform in the tumor microenvironment, which leads to the synergistic enhancement of iron death effect, provides a promising innovative design strategy for tumor research.

Smart Magnetic Nanocarriers for Codelivery of Nitric Oxide and Doxorubicin for Enhanced Apoptosis in Cancer Cells

Extremely short half-life therapeutic molecule nitric oxide (NO) plays significant roles in the functioning of various physiological and pathological processes in the human body, whereas doxorubicin hydrochloride (DOX) is a clinically important anticancer drug widely used in cancer chemotherapy. Thus, the intracellular delivery of these therapeutic molecules is tremendously important to achieve their full potential. Herein, we report a novel approach for the development of highly water-dispersible magnetic nanocarriers for codelivery of NO and DOX. Primarily, bifunctional magnetic nanoparticles enriched with carboxyl and thiol groups were prepared by introducing cysteine onto the surface of citrate-functionalized Fe3O4 nanoparticles. DOX was electrostatically conjugated onto the surface of bifunctional nanoparticles via carboxyl moieties, whereas the thiol group was further nitrosated to provide NO-releasing molecules. The developed magnetic nanocarrier exhibited good aqueous colloidal stability, protein resistance behavior, and high encapsulation efficacy for NO (65.5%) and DOX (85%), as well as sustained release characteristics. Moreover, they showed superior cytotoxicity toward cancer (A549 and MCF-7) cells via apoptosis induction over normal (WI26VA4) cells. Specifically, we have developed magnetic nanocarriers having the capability of dual delivery of NO and DOX, which holds great potential for combinatorial cancer treatment.

Immunomodulator-Mediated Suppressive Tumor Immune Microenvironment Remodeling Nanoplatform for Enhanced Immuno/Chemo/Photothermal Combination Therapy of Triple Negative Breast Cancer

Despite immunotherapy having revolutionized cancer therapy, the efficacy of immunotherapy in triple-negative breast cancer (TNBC) is seriously restricted due to the insufficient infiltration of mature dendritic cells (DCs) and the highly diffusion of immunosuppressive cells in the tumor microenvironment. Herein, an immunomodulatory nanoplatform (HA/Lipo@MTO@IMQ), in which the DCs could be maximally activated, was engineered to remarkably eradicate the tumor via the combination of suppressive tumor immune microenvironment reversal immunotherapy, chemotherapy, and photothermal therapy. It was noticed that the immunotherapy efficacy could be significantly facilitated by this triple-assistance therapy: First, a robust immunogenic cell death (ICD) effect was induced by mitoxantrone hydrochloride (MTO) to boost DCs maturation and cytotoxic T lymphocytes infiltration. Second, the powerful promaturation property of the toll-like receptor 7/8 (TLR7/8) agonist on DCs simultaneously strengthened the ICD effect and restricted antitumor immunity to the tumor bed and lymph nodes. On this basis, tumor-associated macrophages were also dramatically repolarized toward the antitumor M1 phenotype in response to TLR7/8 agonist to intensify the phagocytosis and reverse the immunosuppressive microenvironment. Furthermore, the recruitment of immunocompetent cells and tumor growth inhibition were further promoted by the photothermal characteristic. The nanoplatform with no conspicuous untoward effects exhibited a splendid ability to activate the systemic immune system so as to increase the immunogenicity of the tumor microenvironment, thus enhancing the tumor killing effect. Taken together, HA/Lipo@MTO@IMQ might highlight an efficient combination of therapeutic modality for TNBC.

Current Advances of Atomically Dispersed Metal-Centered Nanozymes for Tumor Diagnosis and Therapy

Nanozymes, which combine enzyme-like catalytic activity and the biological properties of nanomaterials, have been widely used in biomedical fields. Single-atom nanozymes (SANs) with atomically dispersed metal centers exhibit excellent biological catalytic activity due to the maximization of atomic utilization efficiency, unique metal coordination structures, and metal-support interaction, and their structure-activity relationship can also be clearly investigated. Therefore, they have become an emerging alternative to natural enzymes. This review summarizes the examples of nanocatalytic therapy based on SANs in tumor diagnosis and treatment in recent years, providing an overview of material classification, activity modulation, and therapeutic means. Next, we will delve into the therapeutic mechanism of SNAs in the tumor microenvironment and the advantages of synergistic multiple therapeutic modalities (e.g., chemodynamic therapy, sonodynamic therapy, photothermal therapy, chemotherapy, photodynamic therapy, sonothermal therapy, and gas therapy). Finally, this review proposes the main challenges and prospects for the future development of SANs in cancer diagnosis and therapy.

Cascade strategy for glucose oxidase-based synergistic cancer therapy using nanomaterials

Nanomaterial-based cancer therapy faces significant limitations due to the complex nature of the tumor microenvironment (TME). Starvation therapy is an emerging therapeutic approach that targets tumor cell metabolism using glucose oxidase (GOx). Importantly, it can provide a material or environmental foundation for other diverse therapeutic methods by manipulating the properties of the TME, such as acidity, hydrogen peroxide (H2O2) levels, and hypoxia degree. In recent years, this cascade strategy has been extensively applied in nanoplatforms for ongoing synergetic therapy and still holds undeniable potential. However, only a few review articles comprehensively elucidate the rational designs of nanoplatforms for synergetic therapeutic regimens revolving around the conception of the cascade strategy. Therefore, this review focuses on innovative cascade strategies for GOx-based synergetic therapy from representative paradigms to state-of-the-art reports to provide an instructive, comprehensive, and insightful reference for readers. Thereafter, we discuss the remaining challenges and offer a critical perspective on the further advancement of GOx-facilitated cancer treatment toward clinical translation.

Bioengineered "Molecular Glue"-Mediated Tumor-Specific Cascade Nanoreactors with Self-Destruction Ability for Enhanced Precise Starvation/Chemosynergistic Tumor Therapy

The ordered and directed functionalization of targeting elements on the surface of nanomaterials for precise tumor therapy remains a challenge. To address the above problem, herein, we adopted a materials-based synthetic biotechnology strategy to fabricate a bioengineered fusion protein of materials-binding peptides and targeting elements, which can serve as a "molecular glue" to achieve a directional and organized assembly of targeting biological macromolecules on the surface of nanocarriers. The hypoxia microenvironment of solid tumors inspired the rapid development of starvation/chemosynergistic therapy; however, the unsatisfied spatiotemporal specific performance hindered its further development in precise tumor therapy. As a proof of concept, a bioengineered fusion protein containing a dendritic mesoporous silicon (DMSN)-binding peptide, and a tumor-targeted and acidity-decomposable ferritin heavy chain 1 (FTH1), was constructed by fusion expression and further assembled on the surface of DMSN companying with the insertion of hypoxia-activated prodrug tirapazamine (TPZ) and glucose oxidase (GOX) to establish a nanoreactor for precise starvation/chemosynergistic tumor therapy. In this context, the as-prepared therapeutic nanoreactors revealed obvious tumor-specific accumulation and an endocytosis effect. Next, the acidic tumor microenvironment triggered the structural collapse of FTH1 and the subsequent release of GOX and TPZ, in which GOX-mediated catalysis cut off the nutrition supply to realize starvation therapy based on the consumption of endogenous glucose and further provided an exacerbated hypoxia environment for TPZ in situ activation to initiate tumor chemotherapy. More significantly, the presence of "molecular glue" elevated the tumor-targeting capacity of nanoreactors and further enhanced the starvation/chemosynergistic therapeutic effect remarkably, suggesting that such a strategy provided a solution for the functionality of nanomaterials and facilitated the design of novel targeting nanomedicines. Overall, this study highlights materials-binding peptides as a new type of "molecular glue" and opens new avenues for designing and exploring active biological materials for biological functions and applications.

Current advances in nanoformulations of therapeutic agents targeting tumor microenvironment to overcome drug resistance

The tumor microenvironment (TME) plays a pivotal role in cancer development and progression. In this line, revealing the precise mechanisms of the TME and associated signaling pathways of tumor resistance could pave the road for cancer prevention and efficient treatment. The use of nanomedicine could be a step forward in overcoming the barriers in tumor-targeted therapy. Novel delivery systems benefit from enhanced permeability and retention effect, decreasing tumor resistance, reducing tumor hypoxia, and targeting tumor-associated factors, including immune cells, endothelial cells, and fibroblasts. Emerging evidence also indicates the engagement of multiple dysregulated mediators in the TME, such as matrix metalloproteinase, vascular endothelial growth factor, cytokines/chemokines, Wnt/β-catenin, Notch, Hedgehog, and related inflammatory and apoptotic pathways. Hence, investigating novel multitargeted agents using a novel delivery system could be a promising strategy for regulating TME and drug resistance. In recent years, small molecules from natural sources have shown favorable anticancer responses by targeting TME components. Nanoformulations of natural compounds are promising therapeutic agents in simultaneously targeting multiple dysregulated factors and mediators of TME, reducing tumor resistance mechanisms, overcoming interstitial fluid pressure and pericyte coverage, and involvement of basement membrane. The novel nanoformulations employ a vascular normalization strategy, stromal/matrix normalization, and stress alleviation mechanisms to exert higher efficacy and lower side effects. Accordingly, the nanoformulations of anticancer monoclonal antibodies and conventional chemotherapeutic agents also improved their efficacy and lessened the pharmacokinetic limitations. Additionally, the coadministration of nanoformulations of natural compounds along with conventional chemotherapeutic agents, monoclonal antibodies, and nanomedicine-based radiotherapy exhibits encouraging results. This critical review evaluates the current body of knowledge in targeting TME components by nanoformulation-based delivery systems of natural small molecules, monoclonal antibodies, conventional chemotherapeutic agents, and combination therapies in both preclinical and clinical settings. Current challenges, pitfalls, limitations, and future perspectives are also discussed.

pH-Sensitive Biomimetic Nanosystem Based on Large-Pore Mesoporous Silica Nanoparticles with High Hyaluronidase Loading for Tumor Deep Penetration

Loading hyaluronidase (Hyal) in a nanocarrier is a potent strategy to degrade the tumor extracellular matrix for tumor deep penetration and enhanced tumor therapy. Herein, a pH-sensitive biomimicking nanosystem with high Hyal loading, effective tumor targeting, and controllable release is constructed. Specifically, cationic mesoporous silica nanoparticles (CMSNs) with large pores 13.52 nm in diameter were synthesized in a one-pot manner by adding N-[3-trimethoxysilylpropyl]-N,N,N-trimethylammonium to a reversed microemulsion reaction system. The Hyal loading rate was as high as 19.47% owing to matched pore size and the cationic surface charge. Subsequently, a pH-sensitive biomimetic hybrid membrane (pHH) composed of pH-sensitive liposome (pHL), red blood cell membrane, and pancreatic cancer cell membrane was camouflaged on the pHL-coated and doxorubicin/Hyal-loaded CMSNs (shortened as DHCM). The DHCM@pHL@pHH is stable at neutral pH while it releases the payloads smoothly in the tumor acidic microenvironment. Consequently, it can escape from macrophage clearance, be specifically taken up by pancreatic cancer cells, and efficiently accumulate at the tumor site. More importantly, it can penetrate deeply in pancreatic tumors with a tumor growth inhibition ratio of 80.46%. The nanosystem is biocompatible and has potential for clinical transformation, and the nanocarrier is promisingly applicable as a platform for encapsulation of various macromolecules for smart and tumor-targeted delivery.

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.

Gas-assisted phototherapy for cancer treatment

Phototherapies, mainly including photodynamic and photothermal therapy, have made considerable strides in the field of cancer treatment. With the aid of phototherapeutic agents, reactive oxygen species (ROS) or heat are generated under light irradiation to selectively damage cancer cells. However, sole-modality phototherapy faces certain drawbacks, such as limited penetration of phototherapeutic agents into tumor tissues, inefficient ROS generation due to hypoxia, treatment-induced inflammation and resistance of tumor to treatment (e.g., high levels of antioxidants, expression of heat shock protein). Gas therapy, an emerging therapy approach that damages cancer cells by improving the level of certain gas at the tumor site, shows potential to overcome the challenges associated with phototherapies. In addition, with the rapid development of nanotechnology, gas-assisted phototherapy based on nanomedicines has emerged as a promising strategy to enhance the treatment efficacy. This review summarizes recent advances in gas-assisted phototherapy and discusses the prospects and challenges of this strategy in cancer phototherapy.

Tumor Cell Targeting and Responsive Nanoplatform for Multimodal-Imaging Guided Chemodynamic/Photodynamic/Photothermal Therapy toward Triple Negative Breast Cancer

Triple negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, with ineffective treatment and poor prognosis. It is in great demand to develop a novel theranostic strategy for accurate diagnosis and targeted treatment of TNBC. In the present study, one nanoplatform (HA-ICG-Fe-PDA), endowed with multimodal imaging-guided chemodynamic/photodynamic/photothermal (CDT/PDT/PTT) synergistic therapy capacity toward TNBC, was innovatively constructed. The nanoplatform was prepared by covalently conjugating ICG-decorated hyaluronic acid (HA) on Fe³⁺-chelated polydopamine (PDA). HA facilitated the targeting and accumulating of the nanoplatform in tumor tissue and cells of TNBC, thus producing enhanced magnetic resonance signal. Upon entering into TNBC cells, the intracellular hyaluronidase-catalyzed cleavage of HA-ICG-Fe-PDA activated the prequenched near-infrared (NIR) fluorescence signal, allowing for the activatable NIR fluorescence imaging. On the other hand, Fe³⁺ in the nanoplatform could be reduced to reactive Fe²⁺ in tumor microenvironment, guaranteeing efficient Fenton reaction-mediated CDT. The combination of ICG with Fe-PDA enhanced the NIR absorption of the nanoplatform so that considerable PTT/PDT and photothermal imaging were achieved under 808 nm laser irradiation. In vitro and in vivo experiments have verified that the proposed nanoplatform integrates the potential of TNBC-targeting, precise NIR fluorescence/magnetic resonance/photothermal trimodal imaging, efficient treatment via synergistic CDT/PDT/PTT, as well as excellent biocompatibility. Therefore, this multifunctional nanoplatform provides a simple and versatile strategy for imaging-guided theranostics of TNBC.

Multifunctional nanostructures: Intelligent design to overcome biological barriers

Over the past three decades, nanoscience has offered a unique solution for reducing the systemic toxicity of chemotherapy drugs and for increasing drug therapeutic efficiency. However, the poor accumulation and pharmacokinetics of nanoparticles are some of the key reasons for their slow translation into the clinic. The is intimately linked to the non-biological nature of nanoparticles and the aberrant features of solid cancer, which together significantly compromise nanoparticle delivery. New findings on the unique properties of tumors and their interactions with nanoparticles and the human body suggest that, contrary to what was long-believed, tumor features may be more mirage than miracle, as the enhanced permeability and retention based efficacy is estimated to be as low as 1%. In this review, we highlight the current barriers and available solutions to pave the way for approved nanoformulations. Furthermore, we aim to discuss the main solutions to solve inefficient drug delivery with the use of nanobioengineering of nanocarriers and the tumor environment. Finally, we will discuss the suggested strategies to overcome two or more biological barriers with one nanocarrier. The variety of design formats, applications and implications of each of these methods will also be evaluated.

Advanced Nitric Oxide Generating Nanomedicine for Therapeutic Applications

Nitric oxide (NO), a gaseous transmitter extensively present in the human body, regulates vascular relaxation, immune response, inflammation, neurotransmission, and other crucial functions. Nitrite donors have been used clinically to treat angina, heart failure, pulmonary hypertension, and erectile dysfunction. Based on NO's vast biological functions, it further can treat tumors, bacteria/biofilms and other infections, wound healing, eye diseases, and osteoporosis. However, delivering NO is challenging due to uncontrolled blood circulation release and a half-life of under five seconds. With advanced biotechnology and the development of nanomedicine, NO donors packaged with multifunctional nanocarriers by physically embedding or chemically conjugating have been reported to show improved therapeutic efficacy and reduced side effects. Herein, we review and discuss recent applications of NO nanomedicines, their therapeutic mechanisms, and the challenges of NO nanomedicines for future scientific studies and clinical applications. As NO enables the inhibition of the replication of DNA and RNA in infectious microbes, including COVID-19 coronaviruses and malaria parasites, we highlight the potential of NO nanomedicines for antipandemic efforts. This review aims to provide deep insights and practical hints into design strategies and applications of NO nanomedicines.

Recent advances in Prussian blue-based photothermal therapy in cancer treatment

Malignant tumours are a serious threat to human health. Traditional chemotherapy has achieved breakthrough improvements but also has significant detrimental effects, such as the development of drug resistance, immunosuppression, and even systemic toxicity. Photothermal therapy (PTT) is an emerging cancer therapy. Under light irradiation, the phototherapeutic agent converts optical energy into thermal energy and induces the hyperthermic death of target cells. To date, numerous photothermal agents have been developed. Prussian blue (PB) nanoparticles are among the most promising photothermal agents due to their excellent physicochemical properties, including photoacoustic and magnetic resonance imaging properties, photothermal conversion performance, and enzyme-like activity. By the construction of suitably designed PB-based nanotherapeutics, enhanced photothermal performance, targeting ability, multimodal therapy, and imaging-guided cancer therapy can be effectively and feasibly achieved. In this review, the recent advances in PB-based photothermal combinatorial therapy and imaging-guided cancer therapy are comprehensively summarized. Finally, the potential obstacles of future research and clinical translation are discussed.

Prussian Blue-Derived Nanoplatform for In Situ Amplified Photothermal/Chemodynamic/Starvation Therapy

Chemodynamic therapy (CDT) is an emerging tumor treatment; however, it is hindered by insufficient endogenous hydrogen peroxide (H₂O₂) and high glutathione (GSH) concentrations in the tumor microenvironment (TME). Furthermore, CDT has limited therapeutic efficacy as a monotherapy. To overcome these limitations, in this study, a nanoplatform is designed and constructed from Cu-doped mesoporous Prussian blue (CMPB)-encapsulated glucose oxidase (GOx) with a coating of hyaluronic acid (HA) modified with a nitric oxide donor (HN). In the proposed GOx@CMPB-HN nanoparticles, the dopant Cu²⁺ ions are crucial to combining and mutually promoting multiple therapeutic approaches, namely, CDT, photothermal therapy (PTT), and starvation therapy. The dopant Cu²⁺ ions in CMPB protect against reactive oxygen species to deplete the intracellular GSH in the TME. Additionally, the byproduct Cu⁺ ions act as a substrate for a Fenton-like reaction that activates CDT. Moreover, H₂O₂, which is another important substrate, is produced in large quantities through intracellular glucose depletion caused by the nanoparticle-loaded GOx, and the gluconic acid produced in this reaction further enhances the TME acidity and creates a better catalytic environment for CDT. In addition, Cu²⁺ doping greatly improves the mesoporous Prussian blue (MPB) photothermal conversion performance, and the resultant increase in temperature accelerates CDT catalysis. Finally, the HN coating enables the nanoparticles to actively target CD44 receptors in cancer cells and also enhances vascular permeability. Therefore, this coating has multiple effects, such as facilitating enhanced permeability and retention and deep laser penetration. In vitro and in vivo experiments demonstrate that the proposed GOx@CMPB-HN nanoplatform significantly inhibits tumor growth with the help of in situ enhanced synergistic therapies based on the properties of the TME. The developed nanoplatform has the potential to be applied to cancer treatment and introduces new avenues for tumor treatment research.

Construction of a multifunctional peptide nanoplatform for nitric oxide release and monitoring and its application in tumor-bearing mice

As a "star molecule", nitric oxide (NO) either promotes or inhibits many physiological processes depending on its concentration. The in situ generation and monitoring of therapeutic gas molecules has been a problem that many researchers have been working to address due to the stochastic nature of gas molecule movement. There are still relatively few studies using short peptides as NO storage systems, and there are still challenges in monitoring NO release in situ with real-time imaging over long periods of time. In this work, a morphologically transformable NO release, diagnosis and treatment integrated multifunctional nanoplatform was fabricated. A new NO-activated probe (DPBTD) with emission in the first near infrared (NIR-I) region was encapsulated into the hydrophobic domains of Ac-KLVFFAL-NH₂ peptide derivatives as a biosensor for NO release. Peptide scaffolds were endowed with the capacity of controlled NO release by the introduction of NO donor (organic nitrates). Interestingly, morphology of the nanoplatform could be transformed from one-dimensional (1D) nanowires to two-dimensional (2D) nanosheets via nanorods transition state under tip sonication, which was allowed for better cell uptake. Eventually, this nanocarrier was used for stimuli-responsive NO release, real-time imaging and treatment in tumor tissues of 4T1 tumor-bearing mice. This strategy expands the application potential of peptide-based nanomaterials and provides ideas for monitoring the progress of gas-mediated cancer therapy.

Overcoming Cancer Multi-drug Resistance (MDR): Reasons, mechanisms, nanotherapeutic solutions, and challenges

Multi-drug resistance (MDR) in cancer cells, either intrinsic or acquired through various mechanisms, significantly hinders the therapeutic efficacy of drugs. Typically, the reduced therapeutic performance of various drugs is predominantly due to the inherent over expression of ATP-binding cassette (ABC) transporter proteins on the cell membrane, resulting in the deprived uptake of drugs, augmenting drug detoxification, and DNA repair. In addition to various physiological abnormalities and extensive blood flow, MDR cancer phenotypes exhibit improved apoptotic threshold and drug efflux efficiency. These severe consequences have substantially directed researchers in the fabrication of various advanced therapeutic strategies, such as co-delivery of drugs along with various generations of MDR inhibitors, augmented dosage regimens and frequency of administration, as well as combinatorial treatment options, among others. In this review, we emphasize different reasons and mechanisms responsible for MDR in cancer, including but not limited to the known drug efflux mechanisms mediated by permeability glycoprotein (P-gp) and other pumps, reduced drug uptake, altered DNA repair, and drug targets, among others. Further, an emphasis on specific cancers that share pathogenesis in executing MDR and effluxed drugs in common is provided. Then, the aspects related to various nanomaterials-based supramolecular programmable designs (organic- and inorganic-based materials), as well as physical approaches (light- and ultrasound-based therapies), are discussed, highlighting the unsolved issues and future advancements. Finally, we summarize the review with interesting perspectives and future trends, exploring further opportunities to overcome MDR.

pH-sensitive gold nanoclusters labeling with radiometallic nuclides for diagnosis and treatment of tumor

The acidic microenvironment is one of the remarkable features of tumor and is also a reliable target for tumor theranostics. Ultrasmall gold nanoclusters (AuNCs) have good in vivo behaviors, such as non-retention in liver and spleen, renal clearance, and high tumor permeability, and held great potential for developing novel radiopharmaceuticals. Herein, we developed pH-sensitive ultrasmall gold nanoclusters by introducing quaternary ammonium group (TMA) or tertiary amine motifs (C6A) onto glutathione-coated AuNCs (TMA/GSH@AuNCs, C6A-GSH@AuNCs). Density functional theory simulation revealed that radiometal ⁸⁹Sr, ²²³Ra, ⁴⁴Sc, ⁹⁰Y, ¹⁷⁷Lu, ⁸⁹Zr, ^99mTc, ¹⁸⁸Re, ¹⁰⁶Rh, ⁶⁴Cu, ⁶⁸Ga, and ¹¹³Sn could stably dope into AuNCs. Both TMA/GSH@AuNCs and C6A-GSH@AuNCs could assemble into large clusters responding to mild acid condition, with C6A-GSH@AuNCs being more effective. To assess their performance for tumor detection and therapy, TMA/GSH@AuNCs and C6A-GSH@AuNCs were labeled with ⁶⁸Ga, ⁶⁴Cu, ⁸⁹Zr and ⁸⁹Sr, respectively. PET imaging of 4T1 tumor-bearing mice revealed TMA/GSH@AuNCs and C6A-GSH@AuNCs were mainly cleared through kidney, and C6A-GSH@AuNCs accumulated in tumors more efficiently. As a result, ⁸⁹Sr-labeled C6A-GSH@AuNCs eradicated both the primary tumors and their lung metastases. Therefore, our study suggested that GSH-coated AuNCs held great promise for developing novel radiopharmaceuticals that specifically target the tumor acidic microenvironment for tumor diagnosis and treatments.

Engineering nanoparticles boost TNBC therapy by CD24 blockade and mitochondrial dynamics regulation

Although cancer immunotherapy has achieved remarkable progress, the clinical treatment of triple-negative breast cancer (TNBC) is still tough to make a breakthrough. The unsatisfactory therapeutic effect may be attributed to the lack of tumor immunogenicity and the strong immunosuppressive tumor microenvironment (ITM). In order to overcome the above shortcomings, engineering nanoparticles (P-aCD24/CEL + P/shMFN1) was designed to deliver anti-CD24 monoclonal antibody (aCD24), celastrol (CEL) and mitofusin 1 shRNA (shMFN1) for synergistic tumor cells-targeted treatment and tumor-associated macrophages (TAMs)-targeted immunomodulation. CD24, highly expressed on tumor cells, interacts with Siglec10 on TAMs to protect tumor cells from phagocytosis by macrophages, and thus has become a novel and dominant immune checkpoint in TNBC. P-aCD24/CEL achieved the release of aCD24 based on the dual response of carrier to pH and MMP2 in tumor microenvironment. Moreover, CEL increased "eat me" signal CRT and induced the immunogenic cell death (ICD) of tumor cells, together with decreased "don't eat me" signal CD24, reactivated macrophage phagocytosis of tumor cells, and ultimately improves the macrophage-based immunotherapy. On the other hand, P/shMFN1 could target TAMs for mitochondrial dynamics regulation via durable MFN1 silencing in TAMs, thereby reversing the phenotype of M2-TAMs. P-aCD24/CEL and P/shMFN1 could synergistically elicit evident antitumor immune responses and long-term immune memory to significantly inhibit tumor progress and postoperative recurrence. Based on remodeling the ITM and increasing antitumor immune response, this combination immunotherapy strategy showed great potential for TNBC treatment.

A Cyclodiaryliodonium NOX Inhibitor for the Treatment of Pancreatic Cancer via Enzyme-Activatable Targeted Delivery by Sulfated Glycosaminoglycan Derivatives

Pancreatic cancer renders a principal cause of cancer mortalities with a dismal prognosis, lacking sufficiently safe and effective therapeutics. Here, diversified cyclodiaryliodonium (CDAI) NADPH oxidase (NOX) inhibitors are rationally designed with tens of nanomolar optimal growth inhibition, and CD44-targeted delivery is implemented using synthesized sulfated glycosaminoglycan derivatives. The self-assembled nanoparticle-drug conjugate (NDC) enables hyaluronidase-activatable controlled release and facilitates cellular trafficking. NOX inhibition reprograms the metabolic phenotype by simultaneously impairing mitochondrial respiration and glycolysis. Moreover, the NDC selectively diminishes non-mitochondrial reactive oxygen species (ROS) but significantly elevates cytotoxic ROS through mitochondrial membrane depolarization. Transcriptomic profiling reveals perturbed p53, NF-κB, and GnRH signaling pathways interconnected with NOX inhibition. After being validated in patient-derived pancreatic cancer cells, the anticancer efficacy is further verified in xenograft mice bearing heterotopic and orthotopic pancreatic tumors, with extended survival and ameliorated systemic toxicity. It is envisaged that the translation of cyclodiaryliodonium inhibitors with an optimized molecular design can be expedited by enzyme-activatable targeted delivery with improved pharmacokinetic profiles and preserved efficacy.

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.

Applications and challenges of ultra-small particle size nanoparticles in tumor therapy

With the development of nanotechnology, nanomedicines are widely used in tumor therapy. However, biological barriers in the delivery of nanoparticles still limit their application in tumor therapy. As one of the most fundamental properties of nanoparticles, particle size plays a crucial role in the process of the nanoparticles delivery process. It is difficult for large size nanoparticles with fixed size to achieve satisfactory outcomes in every process. In order to overcome the poor penetration of larger size, nanoparticles with ultra-small particle size are proposed, which are more conducive to deep tumor penetration and uniform drug distribution. In this review, the latest progresses and advantages of ultra-small nanoparticles are systematically summarized, the perspectives and challenges of ultra-small nanoparticles strategy for cancer treatment are also discussed.

Metal-phenolic networks with ferroptosis to deliver NIR-responsive CO for synergistic therapy

As an endogenous gasotransmitter, CO has achieved tremendous advances in cancer treatment through selectively killing cancer cells. However, the application of CO in tumor immunotherapy has not been reported and the tumor targeting delivery is still a tremendous challenge. Herein, thermosensitive boronic acid group-containing CO prodrug was synthesized and fabricated with tannic acid (TA) and iron (Fe) to form metal-phenolic networks, and then loaded with near-infrared (NIR) photothermal agent IR820 to form FeCO-IR820@Fe^IIITA for combinational therapy of CO and photothermal therapy. Ferroptosis can also be enhanced due to the Fe³⁺ incorporation. After TA reduced Fe³⁺ into Fe²⁺, Fe²⁺ might lead to intracellular Fenton reaction. Furthermore, in combination with CTLA-4 blockade immunotherapy, FeCO-IR820@Fe^IIITA remarkably inhibited breast tumor growth, suppressed the lung metastasis and improved the antitumor immune response. To summarize, FeCO-IR820@Fe^IIITA provides a potential novel option for CO/photothermal/immune synergistic therapy with enhanced ferroptosis through simple compositions and facile synthesis process.

A ROS-responsive biomimetic nano-platform for enhanced chemo-photodynamic-immunotherapy efficacy

Due to the complex bloodstream components, tumor microenvironment and tumor heterogeneity, traditional nanoparticles have a limited effect (low drug delivery efficiency and poor penetration to the deeper tumor) on eradicating tumors. To solve these challenges, novel platelet membrane-coated nanoparticles (PCDD NPs) were constructed for combined chemo-photodynamic- and immunotherapy of melanoma. The platelet membrane imparted the PCDD nanoparticles with an excellent long circulation effect and tumor targeting ability, which solved the issues of low drug delivery efficiency. After reaching the tumor cells, it releases the drug-loaded CDD micelles, becoming positively charged and facilitating the deep penetration of tumors. Cytotoxic and apoptosis experiments showed that PCDD nanoparticles have the strongest tumor cell killing ability. Based on the excellent results in vitro, PCDD was used to assess anti-tumor and distal tumor inhibition in rat models. The results revealed that the PCDD combined PDT, immunotherapy and chemotherapy could not only inhibit the primary tumor growth (inhibition rate: 92.0%) but also suppress the distant tumor growth (inhibition rate: 90.7%) and lung metastasis, which is far more effective compared to the commercial Taxotere®. Exploration of the molecular mechanism showed that in vivo immune response induced an increase in positive immune responders, suppressed negative immune suppressors, and established an inflammatory tumor immune environment, leading to excellent results in tumor suppression and lung metastasis. In conclusion, this novel multifunctional PCDD nanoparticle is a promising platform for tumor combined chemotherapy, photodynamic therapy (PDT) and immunotherapy.

Doxorubicin hydrochloride and L-arginine co-loaded nanovesicle for drug resistance reversal stimulated by near-infrared light

Drug resistance is accountable for the inadequate outcome of chemotherapy in clinics. The newly emerging role of nitric oxide (NO) to conquer drug resistance has been recognized as a potential strategy. However, it remains a great challenge to realize targeted delivery as well as accurate release of NO at desired sites. Herein, we developed a PEGylated indocyanine green (mPEG-ICG) integrated nanovesicle system (PIDA) to simultaneously load doxorubicin hydrochloride (DOX⋅HCl) and the NO donor L-arginine (L-Arg), which can produce NO triggered by NIR light irradiation and exert multimodal therapy to sensitize drug-resistant cancers. Upon 808 nm irradiation, the NO released from PIDA led to a decrease in mitochondrial membrane potential, an increase in ROS and significant ATP depletion in K562/ADR cells, thus inhibiting cell growth and resolving the problem of drug resistance. Consequently, the in vivo experiment on K562/ADR-bearing nude mice indicated that PIDA nanovesicles achieved significant anticancer efficacy with a tumor inhibition rate of 80.8%. Above all, PIDA nanovesicles offer guidance for designing nanoplatforms for drug-resistant cancer treatment.

Recent advances in diverse nanosystems for nitric oxide delivery in cancer therapy

Gas therapy has been proven to be a promising and advantageous treatment option for cancers. Studies have shown that nitric oxide (NO) is one of the smallest structurally significant gas molecules with great potential to suppress cancer. However, there is controversy and concern about its use as it exhibits the opposite physiological effects based on its levels in the tumor. Therefore, the anti-cancer mechanism of NO is the key to cancer treatment, and rationally designed NO delivery systems are crucial to the success of NO biomedical applications. This review summarizes the endogenous production of NO, its physiological mechanisms of action, the application of NO in cancer treatment, and nano-delivery systems for delivering NO donors. Moreover, it briefly reviews challenges in delivering NO from different nanoparticles and the issues associated with its combination treatment strategies. The advantages and challenges of various NO delivery platforms are recapitulated for possible transformation into clinical applications.

Opportunities for Nitric Oxide in Potentiating Cancer Immunotherapy

Despite nearly 30 years of development and recent highlights of nitric oxide (NO) donors and NO delivery systems in anticancer therapy, the limited understanding of exogenous NO's effects on the immune system has prevented their advancement into clinical use. In particular, the effects of exogenously delivered NO differing from that of endogenous NO has obscured how the potential and functions of NO in anticancer therapy may be estimated and exploited despite the accumulating evidence of NO's cancer therapy-potentiating effects on the immune system. After introducing their fundamentals and characteristics, this review discusses the current mechanistic understanding of NO donors and delivery systems in modulating the immunogenicity of cancer cells as well as the differentiation and functions of innate and adaptive immune cells. Lastly, the potential for the complex modulatory effects of NO with the immune system to be leveraged for therapeutic applications is discussed in the context of recent advancements in the implementation of NO delivery systems for anticancer immunotherapy applications. SIGNIFICANCE STATEMENT: Despite a 30-year history and recent highlights of nitric oxide (NO) donors and delivery systems as anticancer therapeutics, their clinical translation has been limited. Increasing evidence of the complex interactions between NO and the immune system has revealed both the potential and hurdles in their clinical translation. This review summarizes the effects of exogenous NO on cancer and immune cells in vitro and elaborates these effects in the context of recent reports exploiting NO delivery systems in vivo in cancer therapy applications.

Therapeutic gas-releasing nanomedicines with controlled release: Advances and perspectives

Nanoparticle-based drug delivery has become one of the most popular approaches for maximising drug therapeutic potentials. With the notable improvements, a greater challenge hinges on the formulation of gasotransmitters with unique challenges that are not met in liquid and solid active ingredients. Gas molecules upon release from formulations for therapeutic purposes have not really been discussed extensively. Herein, we take a critical look at four key gasotransmitters, that is, carbon monoxide (CO), nitric oxide (NO), hydrogen sulphide (H2S) and sulphur dioxide (SO2), their possible modification into prodrugs known as gas-releasing molecules (GRMs), and their release from GRMs. Different nanosystems and their mediatory roles for efficient shuttling, targeting and release of these therapeutic gases are also reviewed extensively. This review thoroughly looks at the diverse ways in which these GRM prodrugs in delivery nanosystems are designed to respond to intrinsic and extrinsic stimuli for sustained release. In this review, we seek to provide a succinct summary for the development of therapeutic gases into potent prodrugs that can be adapted in nanomedicine for potential clinical use.

A Two-Pronged Strategy for Enhanced Deep-Tumor Penetration and NIR-II Multimodal Imaging-Monitored Photothermal Therapy

The second near-infrared (NIR-II)-induced photothermal therapy (PTT) has attracted a great deal of attention in recent years due to its non-invasiveness and because it uses less energy. However, the penetration of photothermal agents into solid tumors is seriously impeded by the dense-tumor extracellular matrix (ECM) containing cross-linked hyaluronic acid (HA), thereby compromising the ultimate therapeutic effects. Herein, acid-labile metal-organic frameworks were employed as nanocarriers to efficiently mineralize hyaluronidase (HAase) and encapsulate Ag₂S nanodots by a one-pot approach under mild conditions. The obtained nanocomposites (AHZ NPs) maintained enzyme activity and changed in size to prolong blood circulation and complete delivery of the cargo to the tumor. Moreover, the released HAase could specifically break out the HA to loosen ECM and enable the Ag₂S nanodots to breeze through the tumor matrix space and gain access to the deep tumor. Under near-infrared laser irradiation, the AHZ NPs displayed remarkable fluorescence, outstanding photoacoustic signals, and excellent photothermal properties in the whole tumor. This work offers a promising two-pronged strategy via a decrease in nanoparticle size and the degradation of dense ECM for NIR-II multimodal imaging-guided PTT of deep tumors.

Diselenide-crosslinked carboxymethyl chitosan nanoparticles for doxorubicin delivery: Preparation and in vivo evaluation

In this paper, we report a simple approach to fabricate diselenide-crosslinked carboxymethyl chitosan nanoparticles (DSe-CMC NPs) for doxorubicin (DOX) delivery, with disulfide analogs (DS-CMC NPs) as control. DS-CMC NPs and DSe-CMC NPs featured a spherical morphology and narrow size distribution with the average size about 200 nm. Carboxymethyl chitosan (CMC) as the starting material not only improved the biocompatibility of the nanocarriers but also enhanced physiological stability. Due to electrostatic interactions between DOX and CMC, the nanoparticles had high drug encapsulation efficiency (∼25 %). The nanoparticles disintegration and drug release were accelerated by the cleavage of diselenide bonds through oxidation by H₂O₂ or reduction by GSH. In vitro cell experiments revealed that DOX-loaded DSe-CMC NPs possessed the highest drug accumulation and cytotoxicity in tumor cells. Moreover, DOX-loaded DSe-CMC NPs performed the enhanced growth inhibition in vivo than that of DS-CMC NPs. Thus, the diselenide-crosslinked nanoparticles possess great potentials for DOX delivery.

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

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