A Heterojunction Structured WO2.9-WSe2 Nanoradiosensitizer Increases Local Tumor Ablation and Checkpoint Blockade Immunotherapy upon Low Radiation Dose

Tumor Microenvironment-Specific Driven Nanoagents for Synergistic Mitochondria Damage-Related Immunogenic Cell Death and Alleviated Immunosuppression

Despite significant breakthroughs in immunotherapy, the limitations of inadequate immune stimulation and stubborn immune resistance continue to present opportunities and challenges. Therefore, a two-pronged approach, encompassing the activation of immunogenic cell death (ICD) and blocking the indoleamine 2,3-dioxygenase (IDO)-mediated pathway, is devised to elicit systemic anti-tumor immunity and alleviate immunosuppression. Herein, a tumor microenvironment (TME)-specific driven nanoagent is composed of a tetrasulfide bond-bridged mesoporous silica layer (MON) coated up-conversion nanoparticles as a nano-carrier, combines Fe2+, curcumin, and indoximod for operating chemodynamic therapy/chemotherapy/immunotherapy. The consumption of glutathione (GSH) caused by MON degradation, the Fenton reaction of Fe2+, and curcumin triggering mitochondrial damage collectively exacerbate the oxidative stress, leading to a violent immunoreaction and reversal of the immunosuppressive TME through a combination of IDO-inhibitors. Meanwhile, upconversion luminescence (UCL) imaging serves as a significant guiding tool for drug delivery and the treatment of nanoagents. In vivo and in vitro experiment results demonstrate that the nanosystem not only effectively inhibits the growth of primary tumors but also induces immune priming and memory effects to reject re-challenged tumors. The strategy as a complementary approach displays great potential for future immunotherapy along with other multimodal treatment modes.

A narrow-bandgap RuI3 nanoplatform to synergize radiotherapy, photothermal therapy, and thermoelectric dynamic therapy for tumor eradication

Therapeutic resistance is an essential challenge for nanotherapeutics. Herein, a narrow bandgap RuI3 nanoplatform has been constructed firstly to synergize radiotherapy (RT), photothermal therapy (PTT), and thermoelectric dynamic therapy (TEDT) for tumor eradication. Specifically, the photothermal performance of RuI3 can ablate tumor cells while inducing TEDT. Noteworthy, the thermoelectric effect is found firstly in RuI3, which can spontaneously generate an electric field under the temperature gradient, prompting carrier separation and triggering massive ROS generation, thus aggravating oxidative stress level and effectively inhibiting HSP-90 expression. Moreover, RuI3 greatly enhances X-ray deposition owing to its high X-ray attenuation capacity, resulting in a pronounced computed tomography imaging contrast and DNA damage. In addition, RuI3 possesses both catalase-like and glutathione peroxidase-like properties, which alleviate tumor hypoxia and reduce antioxidant resistance, further exacerbating 1O2 production during RT and TEDT. This integrated therapy platform combining PTT, TEDT, and RT significantly inhibits tumor growth. STATEMENT OF SIGNIFICANCE: RuI3 nanoparticles were synthesized for the first time. RuI3 exhibited the highest photothermal properties among iodides, and the photothermal conversion efficiency was 53.38 %. RuI3 was found to have a thermoelectric effect, and the power factor could be comparable to that of most conventional thermoelectric materials. RuI3 possessed both catalase-like and glutathione peroxidase-like properties, which contributed to enhancing the effect of radiotherapy.

Immunological nanomaterials to combat cancer metastasis

Metastasis causes greater than 90% of cancer-associated deaths, presenting huge challenges for detection and efficient treatment of cancer due to its high heterogeneity and widespread dissemination to various organs. Therefore, it is imperative to combat cancer metastasis, which is the key to achieving complete cancer eradication. Immunotherapy as a systemic approach has shown promising potential to combat metastasis. However, current clinical immunotherapies are not effective for all patients or all types of cancer metastases owing to insufficient immune responses. In recent years, immunological nanomaterials with intrinsic immunogenicity or immunomodulatory agents with efficient loading have been shown to enhance immune responses to eliminate metastasis. In this review, we would like to summarize various types of immunological nanomaterials against metastasis. Moreover, this review will summarize a series of immunological nanomaterial-mediated immunotherapy strategies to combat metastasis, including immunogenic cell death, regulation of chemokines and cytokines, improving the immunosuppressive tumour microenvironment, activation of the STING pathway, enhancing cytotoxic natural killer cell activity, enhancing antigen presentation of dendritic cells, and enhancing chimeric antigen receptor T cell therapy. Furthermore, the synergistic anti-metastasis strategies based on the combinational use of immunotherapy and other therapeutic modalities will also be introduced. In addition, the nanomaterial-mediated imaging techniques (e.g., optical imaging, magnetic resonance imaging, computed tomography, photoacoustic imaging, surface-enhanced Raman scattering, radionuclide imaging, etc.) for detecting metastasis and monitoring anti-metastasis efficacy are also summarized. Finally, the current challenges and future prospects of immunological nanomaterial-based anti-metastasis are also elucidated with the intention to accelerate its clinical translation.

Boosting Checkpoint Immunotherapy with Biomimetic Nanodrug Delivery Systems

Immune checkpoint blockade (ICB) has achieved unprecedented progress in tumor immunotherapy by blocking specific immune checkpoint molecules. However, the high biodistribution of the drug prevents it from specifically targeting tumor tissues, leading to immune-related adverse events. Biomimetic nanodrug delivery systems (BNDSs) readily applicable to ICB therapy have been widely developed at the preclinical stage to avoid immune-related adverse events. By exploiting or mimicking complex biological structures, the constructed BNDS as a novel drug delivery system has good biocompatibility and certain tumor-targeting properties. Herein, the latest findings regarding the aforementioned therapies associated with ICB therapy are highlighted. Simultaneously, prospective bioinspired engineering strategies can be designed to overcome the four-level barriers to drug entry into lesion sites. In future clinical translation, BNDS-based ICB combination therapy represents a promising avenue for cancer treatment.

Advances in Nanomaterials for Immunotherapeutic Improvement of Cancer Chemotherapy

Immuno-stimulative effect of chemotherapy (ISECT) is recognized as a potential alternative to conventional immunotherapies, however, the clinical application is constrained by its inefficiency. Metronomic chemotherapy, though designed to overcome these limitations, offers inconsistent results, with effectiveness varying based on cancer types, stages, and patient-specific factors. In parallel, a wealth of preclinical nanomaterials holds considerable promise for ISECT improvement by modulating the cancer-immunity cycle. In the area of biomedical nanomaterials, current literature reviews mainly concentrate on a specific category of nanomaterials and nanotechnological perspectives, while two essential issues are still lacking, i.e., a comprehensive analysis addressing the causes for ISECT inefficiency and a thorough summary elaborating the nanomaterials for ISECT improvement. This review thus aims to fill these gaps and catalyze further development in this field. For the first time, this review comprehensively discusses the causes of ISECT inefficiency. It then meticulously categorizes six types of nanomaterials for improving ISECT. Subsequently, practical strategies are further proposed for addressing inefficient ISECT, along with a detailed discussion on exemplary nanomedicines. Finally, this review provides insights into the challenges and perspectives for improving chemo-immunotherapy by innovations in nanomaterials.

Ultrasound-Triggered Azo Free Radicals for Cervical Cancer Immunotherapy

PD-1 blockade is a first-line treatment for recurrent/metastatic cervical cancer but benefits only a small number of patients due to low preexisting tumor immunogenicity. Using immunogenic cell death (ICD) inducers is a promising strategy for improving immunotherapy, but these compounds are limited by the hypoxic environment of solid tumors. To overcome this issue, the nanosensitizer AIBA@MSNs were designed based on sonodynamic therapy (SDT), which induces tumor cell death under hypoxic conditions through azo free radicals in a method of nonoxygen radicals. Mechanistically, the azo free radicals disrupt both the structure and function of tumor mitochondria by reversing the mitochondrial membrane potential and facilitating the collapse of electron transport chain complexes. More importantly, the AIBA@MSN-based SDT serves as an effective ICD inducer and improves the antitumor immune capacity. The combination of an AIBA@MSN-based SDT with a PD-1 blockade has the potential to improve response rates and provide protection against relapse. This study provides insights into the use of azo free radicals as a promising SDT strategy for cancer treatment and establishes a basic foundation for nonoxygen-dependent SDT-triggered immunotherapy in cervical cancer treatment.

Janus ACSP Nanoparticle for Synergistic Chemodynamic Therapy and Radiosensitization

Protective autophagy and DNA damage repair lead to tumor radio-resistance. Some hypoxic tumors exhibit a low radiation energy absorption coefficient in radiation therapy. High doses of X-rays may lead to side effects in the surrounding normal tissues. In order to overcome the radio-resistance and improve the efficacy of radiotherapy based on the characteristics of the tumor microenvironment, the development of radiosensitizers has attracted much attention. In this study, a Janus ACSP nanoparticle (NP) was developed for chemodynamic therapy and radiosensitization. The reactive oxygen species generated by the Fenton-like reaction regulated the distribution of cell cycles from a radioresistant phase to a radio-sensitive phase. The high-Z element, Au, enhanced the production of hydroxyl radicals (•OH) under X-ray radiation, promoting DNA damage and cell apoptosis. The NP delayed DNA damage repair by interfering with certain proteins involved in the DNA repair signaling pathway. In vivo experiments demonstrated that the combination of the copper-ion-based Fenton-like reaction and low-dose X-ray radiation enhanced the effectiveness of radiotherapy, providing a novel approach for synergistic chemodynamic and radiosensitization therapy. This study provides valuable insights and strategies for the development and application of NPs in cancer treatment.

2D Nanozymes Modulate Gut Microbiota and T-Cell Differentiation for Inflammatory Bowel Disease Management

Intestinal commensal microbiota dysbiosis and immune dysfunction are significant exacerbating factors in inflammatory bowel disease (IBD). To address these problems, Pluronic F-127-coated tungsten diselenide (WSe2 @F127) nanozymes are developed by simple liquid-phase exfoliation. The abundant valence transitions of elemental selenium (Se2- /Se4+ ) and tungsten (W4+ /W6+ ) enable the obtained WSe2 @F127 nanozymes to eliminate reactive oxygen/nitrogen species. In addition, the released tungsten ions are capable of inhibiting the proliferation of Escherichia coli. In a model of dextran sodium sulfate-induced colitis, WSe2 @F127 nanozymes modulate the gut microbiota by increasing the abundance of bacteria S24-7 and significantly reducing the abundance of Enterobacteriaceae. Moreover, WSe2 @F127 nanozymes inhibit T-cell differentiation and improve intestinal immune barrier function in a model of Crohn's disease. The WSe2 @F127 nanozymes effectively alleviate IBD by reducing oxidative stress damage, modulating intestinal microbial populations, and remodeling the immune barrier.

Lactic acid promotes nucleus pulposus cell senescence and corresponding intervertebral disc degeneration via interacting with Akt

The accumulation of metabolites in the intervertebral disc is considered an important cause of intervertebral disc degeneration (IVDD). Lactic acid, which is a metabolite that is produced by cellular anaerobic glycolysis, has been proven to be closely associated with IVDD. However, little is known about the role of lactic acid in nucleus pulposus cells (NPCs) senescence and oxidative stress. The aim of this study was to investigate the effect of lactic acid on NPCs senescence and oxidative stress as well as the underlying mechanism. A puncture-induced disc degeneration (PIDD) model was established in rats. Metabolomics analysis revealed that lactic acid levels were significantly increased in degenerated intervertebral discs. Elimination of excessive lactic acid using a lactate oxidase (LOx)-overexpressing lentivirus alleviated the progression of IVDD. In vitro experiments showed that high concentrations of lactic acid could induce senescence and oxidative stress in NPCs. High-throughput RNA sequencing results and bioinformatic analysis demonstrated that the induction of NPCs senescence and oxidative stress by lactic acid may be related to the PI3K/Akt signaling pathway. Further study verified that high concentrations of lactic acid could induce NPCs senescence and oxidative stress by interacting with Akt and regulating its downstream Akt/p21/p27/cyclin D1 and Akt/Nrf2/HO-1 pathways. Utilizing molecular docking, site-directed mutation and microscale thermophoresis assays, we found that lactic acid could regulate Akt kinase activity by binding to the Lys39 and Leu52 residues in the PH domain of Akt. These results highlight the involvement of lactic acid in NPCs senescence and oxidative stress, and lactic acid may become a novel potential therapeutic target for the treatment of IVDD.

Nanotechnology-enhanced radiotherapy and the abscopal effect: Current status and challenges of nanomaterial-based radio-immunotherapy

Rare but consistent reports of abscopal remission in patients challenge the notion that radiotherapy (RT) is a local treatment; radiation-induced cancer cell death can trigger activation and recruitment of dendritic cells to the primary tumor site, which subsequently initiates systemic immune responses against metastatic lesions. Although this abscopal effect was initially considered an anomaly, combining RT with immune checkpoint inhibitor therapies has been shown to greatly improve the incidence of abscopal responses via modulation of the immunosuppressive tumor microenvironment. Preclinical studies have demonstrated that nanomaterials can further improve the reliability and potency of the abscopal effect for various different types of cancer by (1) altering the cell death process to be more immunogenic, (2) facilitating the capture and transfer of tumor antigens from the site of cancer cell death to antigen-presenting cells, and (3) co-delivering immune checkpoint inhibitors along with radio-enhancing agents. Several unanswered questions remain concerning the exact mechanisms of action for nanomaterial-enhanced RT and for its combination with immune checkpoint inhibition and other immunostimulatory treatments in clinically relevant settings. The purpose of this article is to summarize key recent developments in this field and also highlight knowledge gaps that exist in this field. An improved mechanistic understanding will be critical for clinical translation of nanomaterials for advanced radio-immunotherapy. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Radioiodine-131-Labeled Theranostic Nanoparticles for Transarterial Radioembolization and Chemoembolization Combination Therapy of VX2 Liver Tumor

In interventional treatment, materials are administered into the blood supply artery and directly delivered to tumors, offering proper scenarios for nanomedicine potential clinical applications. Transarterial chemoembolization (TACE) and transarterial radioembolization (TARE) are effective treatment methods for hepatocellular carcinoma (HCC), but postoperative residual tumor may result in intrahepatic recurrence and distant metastasis. The combination therapy of TACE and TARE based on multifunctional nanoparticles (NPs) is expected to overcome the drug resistance in hypoxic tumors and improve the therapeutic effect. Herein, BaGdF5 NPs are synthesized and then coated with polydopamine (PDA), conjugated with the chemotherapeutic drug cis-diamminedichloride platinum (CDDP), radio-labeled with therapeutic radionuclide 131 I, yielding 131 I-BaGdF5 @PDA-CDDP NPs. The in vitro anti-cancer effects of 131 I-BaGdF5 @PDA-CDDP NPs are confirmed using CCK-8 and γ-H2AX assays in Huh7 cells. Mixed with Lipiodol, 131 I-BaGdF5 @PDA-CDDP NPs are injected into the hepatic artery via a microcatheter to realize the TACE and TARE combination therapy in a rabbit VX2 liver tumor model. The results indicate that glucose metabolism is clearly decreased based on 18 F-FDG PET imaging and the apoptosis of tumor cells is increased. Furthermore, 131 I and BaGdF5 NPs can be used for SPECT imaging and CT/MR imaging respectively, facilitating real-time monitoring of the in vivo biodistribution of 131 I-BaGdF5 @PDA-CDDP NPs.

Radiotherapy combined with nano-biomaterials for cancer radio-immunotherapy

Radiotherapy (RT) plays an important role in tumor therapy due to its noninvasiveness and wide adaptation. In recent years, radiation therapy has been discovered to induce an anti-tumor immune response, which arouses widespread concern among scientists and clinicians. In this review, we highlight recent advances in the applications of nano-biomaterials for radiotherapy-activated immunotherapy. We first discuss the combination of different radiosensitizing nano-biomaterials and immune checkpoint inhibitors to enhance tumor immune response and improve radiotherapy efficacy. Subsequently, various nano-biomaterials-enabled tumor oxygenation strategies are introduced to alleviate the hypoxic tumor environment and amplify the immunomodulatory effect. With the aid of nano-vaccines and adjuvants, radiotherapy refreshes the host's immune system. Additionally, ionizing radiation responsive nano-biomaterials raise innate immunity-mediated anti-tumor immunity. At last, we summarize the rapid development of immune modulatable nano-biomaterials and discuss the key challenge in the development of nano-biomaterials for tumor radio-immunotherapy. Understanding the nano-biomaterials-assisted radio-immunotherapy will maximize the benefits of clinical radiotherapy and immunotherapy and facilitate the development of new combinational therapy modality.

Gold Nanoparticles Enhance the Ability of Radiotherapy to Induce Immunogenic Cell Death in Glioblastoma

Background

Radiation therapy (RT) is commonly used to treat glioblastoma, but its immunomodulatory effect on tumors, through mechanisms such as immunogenic cell death (ICD), is relatively weak. Gold nanoparticles (AuNPs) have been suggested as potential radio-sensitizers, but it is unclear if they can enhance radiation-induced ICD. This study aimed to investigate the potential of AuNPs to improve the effectiveness of radiation-induced ICD.

Methods

G422 cells were treated with a combination of AuNPs and RT to induce cell death. Various assays were conducted to assess cell death, surface expression of CRT, and release of HMGB1 and ATP. In vitro co-culture experiments with bone marrow-derived dendritic cells (BMDCs) were performed to analyze the immunogenicity of dying cancer cells. Flow cytometry was used to measure the maturation rate of BMDCs. An in vivo mouse tumor prophylactic vaccination model was employed to assess immunogenicity.

Results

The study findings presented here confirm that the combination of radiotherapy (RT) with AuNPs can induce a stronger ICD effect on glioblastoma cells compared to using RT alone. Specifically, treatment with AuNPs combined with RT resulted in the emission of crucial damage-associated molecular patterns (DAMPs) such as CRT, HMGB1 (479.41±165.34pg/mL vs 216.04±178.16 pg/mL, *P<0.05) and ATP (The release of ATP in the AuNPs + RT group was 1.2 times higher than in the RT group, *P<0.05). The proportion of BMDC maturation rate was higher in the group treated with AuNPs and RT compared to the group treated with RT alone. (32.53±0.52% vs 25.03±0.28%,***P < 0.001). In the tumor vaccine experiment, dying tumor cells treated with AuNPs and RT effectively inhibited tumor growth in mice when exposed to living tumor cells.

Conclusion

These results indicate that AuNPs have the ability to enhance RT-induced ICD.

Reactive oxidative species (ROS)-based nanomedicine for BBB crossing and glioma treatment: current status and future directions

Glioma is the most common primary intracranial tumor in adults with poor prognosis. Current clinical treatment for glioma includes surgical resection along with chemoradiotherapy. However, the therapeutic efficacy is still unsatisfactory. The invasive nature of the glioma makes it impossible to completely resect it. The presence of blood-brain barrier (BBB) blocks chemotherapeutic drugs access to brain parenchyma for glioma treatment. Besides, tumor heterogeneity and hypoxic tumor microenvironment remarkably limit the efficacy of radiotherapy. With rapid advances of nanotechnology, the emergence of a new treatment approach, namely, reactive oxygen species (ROS)-based nanotherapy, provides an effective approach for eliminating glioma via generating large amounts of ROS in glioma cells. In addition, the emerging nanotechnology also provides BBB-crossing strategies, which allows effective ROS-based nanotherapy of glioma. In this review, we summarized ROS-based nanomedicine and their application in glioma treatment, including photodynamic therapy (PDT), photothermal therapy (PTT), chemodynamic therapy (CDT), sonodynamic therapy (SDT), radiation therapy, etc. Moreover, the current challenges and future prospects of ROS-based nanomedicine are also elucidated with the intention to accelerate its clinical translation.

Tellurium-driven maple leaf-shaped manganese nanotherapeutics reshape tumor microenvironment via chemical transition in situ to achieve highly efficient radioimmunotherapy of triple negative breast cancer

The therapeutic efficacy of radioimmunotherapy against triple negative breast cancer (TNBC) is largely limited by the complicated tumor microenvironment (TME) and its immunosuppressive state. Thus developing a strategy to reshape TME is expected to achieve highly efficient radioimmunotherapy. Therefore, we designed and synthesized a tellurium (Te)-driven maple leaf manganese carbonate nanotherapeutics (MnCO₃@Te) by gas diffusion method, but also provided a chemical catalytic strategy in situ to augment ROS level and activate immune cells for improving cancer radioimmunotherapy. As expected, with the help of H₂O₂ in TEM, MnCO₃@Te heterostructure with reversible Mn³⁺/Mn²⁺ transition could catalyze the intracellular ROS overproduction to amplify radiotherapy. In addition, by virtue of the ability to scavenge H⁺ in TME by carbonate group, MnCO₃@Te directly promote the maturation of dendritic cells and macrophage M1 repolarization by stimulator of interferon genes (STING) pathway activation, resulting in remodeling immuno-microenvironment. As a result, MnCO₃@Te synergized with radiotherapy and immune checkpoint blockade therapy effectively inhibited the breast cancer growth and lung metastasis in vivo. Collectively, these findings indicate that MnCO₃@Te as an agonist, successfully overcome radioresistance and awaken immune systems, showing promising potential for solid tumor radioimmunotherapy.

Local Drug Delivery Techniques for Triggering Immunogenic Cell Death

Immunogenic cell death (ICD), a dying state of the cells, encompasses the changes in the conformations of cell surface and the release of damage-associated molecular patterns, which could initiate an adaptive immune response by stimulating the dendritic cells to present antigens to T cells. Advancements in biomaterials, nanomedicine, and micro- and nano-technologies have facilitated the development of effective ICD inducers, but the potential toxicity of these vesicles encountered in drug delivery via intravenous administration hampers their further application. As alternatives, the local drug delivery systems have gained emerging attention due to their ability to prolong the retention of high payloads at the lesions, sequester drugs from harsh environments, overcome biological barriers to exert optimal efficacy, and minimize potential side effects to guarantee bio-safety. Herein, a brief overview of the local drug delivery techniques used for ICD inducers is provided, explaining how these techniques broaden, alter, and enhance the therapeutic capability while circumventing systemic toxicity at the same time. The historical context and prominent examples of the local administration of ICD inducers are introduced. The complexities, potential pitfalls, and opportunities for local drug delivery techniques in cancer immunotherapy are also discussed.

Flexible use of commercial rhenium disulfide for various theranostic applications

Rhenium disulfide (ReS2) with distinct physicochemical properties has shown promising potential in disease theranostics, such as drug delivery, computed tomography (CT), radiotherapy, and photothermal therapy (PTT). However, the synthesis and post-modification of ReS2 agents for different application scenarios are time- and energy-consuming, which seriously hinders the clinical translation of ReS2. Herein, we proposed three facile excipient strategies for different theranostic applications of ReS2 just through the flexible use of commercial ReS2 powder. Three excipients, including sodium alginate (ALG), xanthan gum (XG), and ultraviolet-cured resin (UCR), were used to prepare different dosage forms of commercial ReS2 powder, like hydrogel, suspension, and capsule, respectively. These dosage forms of ReS2 with distinct characteristics showed great potential for second near-infrared window PTT against tumours, gastric spectral CT imaging, and functional evaluation of the digestive tract in vivo. In addition, these ReS2 formulations exhibited good biocompatibility both in vitro and in vivo, showing a promising prospect for clinical transformation. More importantly, the facile excipient strategies for commercial agents pave a bridge to the development and wide bioapplication of many other theranostic biomaterials.

Mitochondria-Targeted Nanosystem Enhances Radio-Radiodynamic-Chemodynamic Therapy on Triple Negative Breast Cancer

Radiodynamic therapy (RDT), which produces ¹O₂ and other reactive oxygen species (ROS) in response to X-rays, can be used in conjunction with radiation therapy (RT) to drastically lower X-ray dosage and reduce radio resistance associated with conventional radiation treatment. However, radiation-radiodynamic therapy (RT-RDT) is still impotent in a hypoxic environment in solid tumors due to its oxygen-dependent nature. Chemodynamic therapy (CDT) can generate reactive oxygen species and O₂ by decomposing H₂O₂ in hypoxic cells and thus potentiate RT-RDT to achieve synergy. Herein, we developed a multifunctional nanosystem, AuCu-Ce6-TPP (ACCT), for RT-RDT-CDT. Ce6 photosensitizers were conjugated to AuCu nanoparticles via Au-S bonds to realize radiodynamic sensitization. Cu can be oxidized by H₂O₂ and catalyze the degradation of H₂O₂ to generate ^•OH through the Fenton-like reaction to realize CDT. Meanwhile, the degradation byproduct oxygen can alleviate hypoxia while Au can consume glutathione to increase the oxidative stress. We then attached mercaptoethyl-triphenylphosphonium (TPP-SH) to the nanosystem, targeting ACCT to mitochondria (colocalization Pearson coefficient 0.98) to directly disrupt mitochondrial membranes and more efficiently induce apoptosis. We confirmed that ACCT efficiently generates ¹O₂ and ^•OH upon X-ray irradiation, resulting in strong anticancer efficacy in both normoxic and hypoxic 4T1 cells. The down-regulation of hypoxia-inducible factor 1α expression and reduction of intracellular H₂O₂ concentrations suggested that ACCT could significantly alleviate hypoxia in 4T1 cells. ACCT-enhanced RT-RDT-CDT can successfully shrink or remove tumors in radioresistant 4T1 tumor-bearing mice upon 4 Gy of X-ray irradiation. Our work thus presents a new strategy to treat radioresistant hypoxic tumors.

Application of nano-radiosensitizers in combination cancer therapy

Radiosensitizers are compounds or nanostructures, which can improve the efficiency of ionizing radiation to kill cells. Radiosensitization increases the susceptibility of cancer cells to radiation-induced killing, while simultaneously reducing the potentially damaging effect on the cellular structure and function of the surrounding healthy tissues. Therefore, radiosensitizers are therapeutic agents used to boost the effectiveness of radiation treatment. The complexity and heterogeneity of cancer, and the multifactorial nature of its pathophysiology has led to many approaches to treatment. The effectiveness of each approach has been proven to some extent, but no definitive treatment to eradicate cancer has been discovered. The current review discusses a broad range of nano-radiosensitizers, summarizing possible combinations of radiosensitizing NPs with several other types of cancer therapy options, focusing on the benefits and drawbacks, challenges, and future prospects.

Activating Nanomedicines with Electromagnetic Energy for Deep-Tissue Induction of Immunogenic Cell Death in Cancer Immunotherapy

Immunotherapy is an attractive approach for cancer therapy, while its antitumor efficacy is still limited, especially for non-immunogenic tumors. Nanomedicines can be utilized to convert the non-immunogenic "cold" tumors to immunogenic "hot" tumors via inducing immunogenic cell death (ICD), thereby promoting the antitumor immune response. Some nanomedicines that can produce local heat and reactive oxygen species upon the stimulation of electromagnetic energy are the main candidates for inducing the ICD effect. However, their applications are often restricted due to the poor tissue penetration depths of electromagnetic energy, such as light. By contrast, ultrasound, X-ray, alternating magnetic field, and microwave show excellent tissue penetration depths and thereby can be used for sonodynamic therapy, radiotherapy, magnetic hyperthermia therapy, and microwave ablation therapy, all of which can effectively induce ICD. Herein, the combination of deep-tissue electromagnetic energy with nanomedicines for inducing ICD and cancer immunotherapy are summarized. In particular, the designs of nanomedicines to amplify ICD effect in the presence of deep-tissue electromagnetic energy and sensitize tumors to various immunotherapies will be discussed. At the end of this review, a brief conclusion and discussion of current challenges and further perspectives in this subfield are provided.

NIR-II-absorbing diimmonium polymer agent achieves excellent photothermal therapy with induction of tumor immunogenic cell death

Photothermal therapy has shown great promise for cancer treatment and second near-infrared (NIR-II) -absorbing particles could further improve its precision and applicability due to its superior penetration depth and new imaging ability. Herein, high NIR-II-absorbing polymer particles were prepared by using soluble isobutyl-substituted diammonium borates (P-IDI). The P-IDI showed stronger absorption at 1000-1100 nm, which exhibited excellent photostability, strong photoacoustic imaging ability and high photothermal conversion efficiency (34.7%). The investigations in vitro and in vivo demonstrated that the excellent photothermal effect facilitated complete tumor ablation and also triggered immunogenic cell death in activation of the immune response. The high solubility and excellent photothermal conversion ability demonstrated that polymer IDI particles were promising theranostic agents for treatment of tumors with minor side effects.

Large Range Atomic Force Microscopy with High Aspect Ratio Micropipette Probe for Deep Trench Imaging

Atomic force microscopy (AFM) has been adopted in both industry and academia for high-fidelity, full-profile topographic characterization. Typically, the tiny tip of the cantilever and the limited traveling range of the scanner restrict AFM measurement to relatively flat samples (recommend 1 µm). The primary objective of this work is to address these limitations using a large-range AFM (measuring height >10 µm) system consisting of a novel repairable high aspect ratio probe (HARP) with a nested-proportional-integral-derivative (nested-PID) AFM system. The HARP is fabricated using a reliable, cost-efficient bench-top process. The tip is then fused by pulling the end of the micropipette cantilever with a length up to hundreds of micrometers and a tip diameter of 30 nm. The design, simulation, fabrication, and performance of the HARP are described herein. This instrument is then tested using polymer trenches which reveals superior image fidelity compared to standard silicon tips. Finally, a nested-PID system is developed and employed to facilitate 3D characterization of 50-µm-step samples. The results demonstrate the efficacy of the proposed bench-top technique for the fabrication of low-cost, simple HAR AFM probes that facilitate the imaging of samples with deep trenches.

Immunostimulant In Situ Fibrin Gel for Post-operative Glioblastoma Treatment by Macrophage Reprogramming and Photo-Chemo-Immunotherapy

Tumor recurrence remains the leading cause of treatment failure following surgical resection of glioblastoma (GBM). M2-like tumor-associated macrophages (TAMs) infiltrating the tumor tissue promote tumor progression and seriously impair the efficacy of chemotherapy and immunotherapy. In addition, designing drugs capable of crossing the blood-brain barrier and eliciting the applicable organic response is an ambitious challenge. Here, we propose an injectable nanoparticle-hydrogel system that uses doxorubicin (DOX)-loaded mesoporous polydopamine (MPDA) nanoparticles encapsulated in M1 macrophage-derived nanovesicles (M1NVs) as effectors and fibrin hydrogels as in situ delivery vehicles. In vivo fluorescence imaging shows that the hydrogel system triggers photo-chemo-immunotherapy to destroy remaining tumor cells when delivered to the tumor cavity of a model of subtotal GBM resection. Concomitantly, the result of flow cytometry indicated that M1NVs comprehensively improved the immune microenvironment by reprogramming M2-like TAMs to M1-like TAMs. This hydrogel system combined with a near-infrared laser effectively promoted the continuous infiltration of T cells, restored T cell effector function, inhibited the infiltration of myeloid-derived suppressor cells and regulatory T cells, and thereby exhibited a strong antitumor immune response and significantly inhibited tumor growth. Hence, MPDA-DOX-NVs@Gel (MD-NVs@Gel) presents a unique clinical strategy for the treatment of GBM recurrence.

Recent advances in stimuli-responsive nano-heterojunctions for tumor therapy

Stimuli-responsive catalytic therapy based on nano-catalysts has attracted much attention in the field of biomedicine for tumor therapy, due to its excellent and unique properties. However, the complex tumor microenvironment conditions and the rapid charge recombination in the catalyst limit catalytic therapy's effectiveness and further development. Effective heterojunction nanomaterials are constructed to address these problems to improve catalytic performance. Specifically, on the one hand, the band gap of the material is adjusted through the heterojunction structure to promote the charge separation efficiency under exogenous stimulation and further improve the catalytic capacity. On the other hand, the construction of a heterojunction structure can not only preserve the function of the original catalyst but also achieve significantly enhanced synergistic therapy ability. This review summarized the construction and functions of stimuli-responsive heterojunction nanomaterials under the excitation of X-rays, visible-near infrared light, and ultrasound in recent years, and further introduces their application in cancer therapy. Hopefully, the summary of stimuli-responsive heterojunction nanomaterials' applications will help researchers promote the development of nanomaterials in cancer therapy.

Rational Design of Biomaterials to Potentiate Cancer Thermal Therapy

Cancer thermal therapy, also known as hyperthermia therapy, has long been exploited to eradicate mass lesions that are now defined as cancer. With the development of corresponding technologies and equipment, local hyperthermia therapies such as radiofrequency ablation, microwave ablation, and high-intensity focused ultrasound, have has been validated to effectively ablate tumors in modern clinical practice. However, they still face many shortcomings, including nonspecific damages to adjacent normal tissues and incomplete ablation particularly for large tumors, restricting their wide clinical usage. Attributed to their versatile physiochemical properties, biomaterials have been specially designed to potentiate local hyperthermia treatments according to their unique working principles. Meanwhile, biomaterial-based delivery systems are able to bridge hyperthermia therapies with other types of treatment strategies such as chemotherapy, radiotherapy and immunotherapy. Therefore, in this review, we discuss recent progress in the development of functional biomaterials to reinforce local hyperthermia by functioning as thermal sensitizers to endow more efficient tumor-localized thermal ablation and/or as delivery vehicles to synergize with other therapeutic modalities for combined cancer treatments. Thereafter, we provide a critical perspective on the further development of biomaterial-assisted local hyperthermia toward clinical applications.

Multifunctional Dendritic Au@SPP@DOX Nanoparticles Integrating Chemotherapy and Low-Dose Radiotherapy for Enhanced Anticancer Activity

Combined chemoradiotherapy can improve antitumor efficiency and reduce the side effects of monotherapy. In this study, we aimed to construct dendritic peptide-based multifunctional nanoparticles (Au@SPP@DOX) for a prolonged circulation time, enhanced cellular uptake, and targeted cancer therapy. Amphiphilic micelle PEG-polylysine-SA (SPP) is composed of polylysine combined with hydrophilic poly(ethylene glycol) (PEG) and hydrophobic stearic acid (SA). Doxorubicin (DOX) is loaded via the hydrophilic-hydrophobic interaction of SPP, and gold nanoparticles (AuNPs) are loaded via the electrostatic interaction with SPP. Au@SPP@DOX showed good biocompatibility and could be successfully accumulated at tumor sites through the enhanced permeability and retention (EPR) effect. Then, lysosomes could be ruptured due to the proton sponge effect. DOX became protonated in response to tumor extracellular acidity and was then released from SPP. Under the action of low-dose radiation, Au@SPP@DOX could promote the production of reactive oxygen species (ROS), increase mitochondrial dysfunction, block cell division, and ultimately promote tumor cell apoptosis to achieve a better antitumor effect. This study highlighted the benefit of chemoradiotherapy and suggested that Au@SPP@DOX might serve as a high-efficiency codelivery system for cancer combination therapy in the future.

Novel strategies for tumor radiosensitization mediated by multifunctional gold-based nanomaterials

Radiotherapy (RT) is one of the most effective and commonly used cancer treatments for malignant tumors. However, the existing radiosensitizers have a lot of side effects and poor efficacy, which limits the curative effect and further application of radiotherapy. In recent years, emerging nanomaterials have shown unique advantages in enhancing radiosensitization. In particular, gold-based nanomaterials, with high X-ray attenuation capacity, good biocompatibility, and promising chemical, electronic and optical properties, have become a new type of radiotherapy sensitizer. In addition, gold-based nanomaterials can be used as a carrier to load a variety of drugs and immunosuppressants; in particular, its photothermal therapy, photodynamic therapy and multi-mode imaging functions aid in providing excellent therapeutic effect in coordination with RT. Recently, many novel strategies of radiosensitization mediated by multifunctional gold-based nanomaterials have been reported, which provides a new idea for improving the efficacy and reducing the side effects of RT. In this review, we systematically summarize the recent progress of various new gold-based nanomaterials that mediate radiosensitization and describe the mechanism. We further discuss the challenges and prospects in the field. It is hoped that this review will help researchers understand the latest progress of gold-based nanomaterials for radiosensitization, and encourage people to optimize the existing methods or explore novel approaches for radiotherapy.

Tween-20-Modified BiVO4 Nanorods for CT Imaging-Guided Radiotherapy of Tumor

Oral cancer is the most common malignant tumor in the oral and maxillofacial region, which seriously threatens the health of patients. At present, radiotherapy is one of the commonly used methods for oral cancer treatment. However, the resistance of cancerous tissues to ionizing radiation, as well as the side effects of X-rays on healthy tissues, still limit the application of radiotherapy. Therefore, how to effectively solve the above problems is still a challenge at present. Generally speaking, elements with high atomic numbers, such as bismuth, tungsten, and iodine, have a high X-ray attenuation capacity. Using nanomaterials containing these elements as radiosensitizers can greatly improve the radiotherapy effect. At the same time, the modification of nanomaterials based on the above elements with the biocompatible polymer can effectively reduce the side effects of radiosensitizers, providing a new method for the realization of efficient and safe radiotherapy for oral cancer. In this work, we prepared Tween-20-modified BiVO₄ nanorods (Tw20-BiVO₄ NRs) and further used them in the radiotherapy of human tongue squamous cell carcinoma. Tw20-BiVO₄ NRs are promising radiosensitizers, which can generate a large number of free radicals under X-rays, leading to the damage of cancer cells and thus playing a role in tumor therapy. In cell experiments, radiotherapy sensitization of Tw20-BiVO₄ NRs significantly enhanced the production of free radicals in oral cancer cells, aggravated the destruction of chromosomes, and improved the therapeutic effect of radiotherapy. In animal experiments, the strong X-ray absorption ability of Tw20-BiVO₄ NRs makes them effective contrast agents in computed tomography (CT) imaging. After the tumors are located by CT imaging, it helps to apply precise radiotherapy; the growth of subcutaneous tumors in nude mice was significantly inhibited, confirming the remarkable effect of CT imaging-guided radiotherapy.

Mussel-Inspired Tantalum Nanocomposite Hydrogels for In Situ Oral Cancer Treatment

Oral squamous cell carcinoma (OSCC) is one of the most common oral malignancies. Radiotherapy is the primary noninvasive treatment of OSCC for avoiding surgery-induced facial deformities and impaired oral function. However, the specificity of in situ OSCC limits radiotherapeutic effects because of the hypoxia-induced low radiosensitivity of tumors and the low radiation tolerance of surrounding normal tissues. Here, we design a highly efficient and low-toxic radiosensitization strategy. On the one hand, biocompatible poly(vinyl pyrrolidone)-modified tantalum nanoparticles (Ta@PVP NPs) not only have strong X-ray deposition capability to upregulate oxidative stress but also have photothermal conversion efficiency to improve hypoxia for tumor radiosensitivity. On the other hand, to optimize the spatial distribution of Ta@PVP NPs within tumors, mussel-inspired catechol with bioadhesive properties is grafted on tumor microenvironment-responsive sodium alginate (DAA) to form in situ hydrogels for precision radiotherapy. On this basis, we find that Ta@PVP-DAA hydrogels effectively inhibit OSCC development in mice under photothermal-assisted radiotherapy without facial deformities and damage to surrounding normal tissues. Overall, our work not only promotes the exploration of Ta@PVP NPs as new radiosensitizers for OSCC but also develops a nanocomposite hydrogel system strategy as a promising paradigm for the precision treatment of orthotopic tumors.

Nanomedicine embraces cancer radio-immunotherapy: mechanism, design, recent advances, and clinical translation

Cancer radio-immunotherapy, integrating external/internal radiation therapy with immuno-oncology treatments, emerges in the current management of cancer. A growing number of pre-clinical studies and clinical trials have recently validated the synergistic antitumor effect of radio-immunotherapy, far beyond the "abscopal effect", but it suffers from a low response rate and toxicity issues. To this end, nanomedicines with an optimized design have been introduced to improve cancer radio-immunotherapy. Specifically, these nanomedicines are elegantly prepared by incorporating tumor antigens, immuno- or radio-regulators, or biomarker-specific imaging agents into the corresponding optimized nanoformulations. Moreover, they contribute to inducing various biological effects, such as generating in situ vaccination, promoting immunogenic cell death, overcoming radiation resistance, reversing immunosuppression, as well as pre-stratifying patients and assessing therapeutic response or therapy-induced toxicity. Overall, this review aims to provide a comprehensive landscape of nanomedicine-assisted radio-immunotherapy. The underlying working principles and the corresponding design strategies for these nanomedicines are elaborated by following the concept of "from bench to clinic". Their state-of-the-art applications, concerns over their clinical translation, along with perspectives are covered.

Targeted CuFe2O4 hybrid nanoradiosensitizers for synchronous chemoradiotherapy

Multifunctional nanoplatforms based on novel bimetallic nanoparticles have emerged as effective radiosensitizers owing to their potential capability in cancer cells radiosensitization. Implementation of chemotherapy along with radiotherapy, known as synchronous chemoradiotherapy, can augment the treatment efficacy. Herein, a tumor targeted nanoradiosensitizer with synchronous chemoradiotion properties, termed as CuFe₂O₄@BSA-FA-CUR, loaded with curcumin (CUR) and modified by bovine serum albumin (BSA) and folic acid (FA) was developed to enhance tumor accumulation and promote the anti-cancer activity while attenuating adverse effects. Both copper (Cu) and iron (Fe) were utilized in the construction of these submicron scale entities, therefore strong radiosensitization effect is anticipated by implementation of these two metals. The structure-function relationships between constituents of nanomaterials and their function led to the development of nanoscale materials with great radiosensitizing capacity and biosafety. BSA was used to anchor Fe and Cu ions but also to improve colloidal stability, blood circulation time, biocompatibility, and further functionalization. Moreover, to specifically target tumor sites and enhance cellular uptake, FA was conjugated onto the surface of hybrid bimetallic nanoparticles. Finally, CUR as a natural chemotherapeutic agent was encapsulated into the developed bimetallic nanoparticles. With incorporation of all abovementioned stages into one multifunctional nanoplatform, CuFe₂O₄@BSA-FA-CUR is produced for synergistic chemoradiotherapy with positive outcomes. In vitro investigation revealed that these nanoplatforms bear excellent biosafety, great tumor cell killing ability and radiosensitizing capacity. In addition, high cancer-suppression efficiency was observed through in vivo studies. It is worth mentioning that co-use of CuFe₂O₄@BSA-FA-CUR nanoplatforms and X-ray radiation led to complete tumor ablation in almost all of the treated mice. No mortality or radiation-induced normal tissue toxicity were observed following administration of CuFe₂O₄@BSA-FA-CUR nanoparticles which highlights the biosafety of these submicron scale entities. These results offer powerful evidence for the potential capability of CuFe₂O₄@BSA-FA-CUR in radiosensitization of malignant tumors and opens up a new avenue of research in this area.

Research Progress of Nanomedicine-Based Mild Photothermal Therapy in Tumor

With the booming development of nanomedicine, mild photothermal therapy (mPTT, 42-45°C) has exhibited promising potential in tumor therapy. Compared with traditional PTT (>50°C), mPTT has less side effects and better biological effects conducive to tumor treatment, such as loosening the dense structure in tumor tissues, enhancing blood perfusion, and improving the immunosuppressive microenvironment. However, such a relatively low temperature cannot allow mPTT to completely eradicate tumors, and therefore, substantial efforts have been conducted to optimize the application of mPTT in tumor therapy. This review extensively summarizes the latest advances of mPTT, including two sections: (1) taking mPTT as a leading role to maximize its effect by blocking the cell defense mechanisms, and (2) regarding mPTT as a supporting role to assist other therapies to achieve synergistic antitumor curative effect. Meanwhile, the special characteristics and imaging capabilities of nanoplatforms applied in various therapies are discussed. At last, this paper puts forward the bottlenecks and challenges in the current research path of mPTT, and possible solutions and research directions in future are proposed correspondingly.

Nanotechnology meets glioblastoma multiforme: Emerging therapeutic strategies

Glioblastoma multiforme (GBM) represents the most common and fatal form of primary invasive brain tumors as it affects a great number of patients each year and has a median overall survival of approximately 14.6 months after diagnosis. Despite intensive treatment, almost all patients with GBM experience recurrence, and their 5-year survival rate is approximately 5%. At present, the main clinical treatment strategy includes surgical resection, radiotherapy, and chemotherapy. However, tumor heterogeneity, blood-brain barrier, glioma stem cells, and DNA damage repair mechanisms hinder efficient GBM treatment. The emergence of nanometer-scale diagnostic and therapeutic approaches in cancer medicine due to the establishment of nanotechnology provides novel and promising tools that will allow us to overcome these difficulties. This review summarizes the application and recent progress in nanotechnology-based monotherapies (e.g., chemotherapy) and combination cancer treatment strategies (chemotherapy-based combined cancer therapy) for GBM and describes the synergistic enhancement between these combination therapies as well as the current standard therapy for brain cancer and its deficiencies. These combination therapies that can reduce individual drug-related toxicities and significantly enhance therapeutic efficiency have recently undergone rapid development. The mechanisms underlying these different nanotechnology-based therapies as well as the application of nanotechnology in GBM (e.g., in photodynamic therapy and chemodynamic therapy) have been systematically summarized here in an attempt to review recent developments and to identify promising directions for future research. This review provides novel and clinically significant insights and directions for the treatment of GBM, which is of great clinical importance. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Diagnostic Tools > In Vivo Nanodiagnostics and Imaging.

The development of live microorganism-based oxygen shuttles for enhanced hypoxic tumor therapy

Hypoxia is a prominent feature of malignant tumors and contributes to tumor proliferation, metastasis, and drug resistance in various solid tumors. Therefore, improving tumor oxygenation is crucial for curing tumors. To date, multiple strategies, including oxygen delivering and producing materials, have been designed to increase the oxygen concentration in hypoxic tumors. However, the unsustainable supply of oxygen is still the main obstacle, resulting in a suboptimal outcome in treating oxygen-deprived tumors. Thus, a sufficient oxygen supply is highly desirable in the treatment of hypoxic tumors. Photosynthesis, as the main source of oxygen in nature through the conversion of light energy into chemical energy and oxygen, has been widely studied in scientific research. Moreover, photosynthetic microorganisms have been increasingly applied in cancer therapy by increasing oxygenation, which improves the therapeutic effect of oxygen-consuming tumor therapeutic tools such as radiotherapy and photodynamic therapy. In this review, we summarize recent advances in the design and manufacture of live bacteria as oxygen shuttles for a new generation of hypoxic tumor treatment strategies. Finally, current challenges and future directions are also discussed for successfully addressing hypoxic tumor issues.

Biomimetic Yolk-Shell Nanocatalysts for Activatable Dual-Modal-Image-Guided Triple-Augmented Chemodynamic Therapy of Cancer

Fenton reaction-based chemodynamic therapy (CDT), which applies metal ions to convert less active hydrogen peroxide (H₂O₂) into more harmful hydroxyl peroxide (·OH) for tumor treatment, has attracted increasing interest recently. However, the CDT is substantially hindered by glutathione (GSH) scavenging effect on ·OH, low intracellular H₂O₂ level, and low reaction rate, resulting in unsatisfactory efficacy. Here, a cancer cell membrane (CM)-camouflaged Au nanorod core/mesoporous MnO₂ shell yolk-shell nanocatalyst embedded with glucose oxidase (GOD) and Dox (denoted as AMGDC) is constructed for synergistic triple-augmented CDT and chemotherapy of tumor under MRI/PAI guidance. Benefiting from the homologous adhesion and immune escaping property of the cancer CM, the nanocatalysts can target tumor and gradually accumulate in tumor site. For triple-augmented CDT, first, the MnO₂ shell reacts with intratumoral GSH to generate Mn²⁺ and glutathione disulfide, which achieves Fenton-like ion delivery and weakening of GSH-mediated scavenging effect, leading to GSH depletion-enhanced CDT. Second, the intratumoral glucose can be oxidized to H₂O₂ and gluconic acid by GOD, achieving supplementary H₂O₂-enhanced CDT. Next, the AuNRs absorbing in NIR-II elevate the local tumor temperature upon NIR-II laser irradiation, achieving photothermal-enhanced CDT. Dox is rapidly released for adjuvant chemotherapy due to responsive degradation of MnO₂ shell. Moreover, GSH-activated PAI/MRI can be used to monitor CDT process. This study provides a great paradigm for enhancing CDT-mediated antitumor efficacy.

Nanotherapeutics for immune network modulation in tumor microenvironments

Immunotherapy has shown promise in cancer treatment, and is thus drawing increasing interest in this field. While the standard chemotherapy- and/or radiotherapy-based cancer treatments aim to directly kill cancer cells, immunotherapy uses host immune cell surveillance to fight cancer. In the tumor environment, there is a close relationship between tumor cells and the adjacent immune cells, which are largely suppressed by cancer-related regulation of immune checkpoints, immune-suppressive cytokines, and metabolic factors. The immune modulators currently approved for cancer treatment remain limited by issues with dose tolerance and insufficient efficacy. Researchers have developed and tested various nano-delivery systems with the goal of improving the treatment outcome of these drugs. By encapsulating immune modulators in particles and directing their tissue accumulation, some such systems have decreased immune-related toxicity while sharpening the antitumor response. Surface-ligand modification of nanoparticles has allowed drugs to be delivered to specific immune cells types. Researchers have also studied strategies for depleting or reprogramming the immune-suppressive cells to recover the immune environment. Combining a nanomaterial with an external stimulus has been used to induce immunogenic cell death; this favors the inflammatory environment found in tumor tissues to promote antitumor immunity. The present review covers the most recent strategies aimed at modulating the tumor immune environment, and discusses the challenges and future perspectives in developing nanoparticles for cancer immunotherapy.

Ultrasmall zirconium carbide nanodots for synergistic photothermal-radiotherapy of glioma

Glioma is characterized by highly invasive, progressive, and lethal features. In addition, conventional treatments have been poorly effective in treating glioma. To overcome this challenge, synergistic therapies combining radiotherapy (RT) with photothermal therapy (PTT) have been proposed and extensively explored as a highly feasible cancer treatment strategy. Herein, ultrasmall zirconium carbide (ZrC) nanodots were successfully synthesized with high near-infrared absorption and strong photon attenuation for synergistic PTT-RT of glioma. ZrC-PVP nanodots with an average size of approximately 4.36 nm were prepared by the liquid exfoliation method and modified with the surfactant polyvinylpyrrolidone (PVP), with a satisfactory absorption and photothermal conversion efficiency (53.4%) in the near-infrared region. Furthermore, ZrC-PVP nanodots can also act as radiosensitizers to kill residual tumor cells after mild PTT due to their excellent photon attenuating ability, thus achieving a significant synergistic therapeutic effect by combining RT and PTT. Most importantly, both in vitro and in vivo experimental results further validate the high biosafety of ZrC-PVP NDs at the injected dose. This work systematically evaluates the feasibility of ZrC-PVP NDs for glioma treatment and provides evidence of the application of zirconium-based nanomaterials in photothermal radiotherapy.

Self-targeting platinum(IV) amphiphilic prodrug nano-assembly as radiosensitizer for synergistic and safe chemoradiotherapy of hepatocellular carcinoma

Chemoradiotherapy is a widely used treatment for patients with malignancies such as hepatocellular carcinoma (HCC). However, it remains challenging to realize safe and synergistic chemotherapy and radiation sensitization. Herein, we design a self-targeting nano-assembly (STNA) based on platinum(IV)-lactose amphiphilic prodrug for synergistic and safe chemoradiotherapy of HCC. The Pt STNA would improve the tumor accumulation due to the targeting ability of lactose to HCC cells. After receptor-mediated endocytosis, Pt STNA would release cisplatin(II) in cancer cells to form DNA-binding, thus inducing DNA damage and cell apoptosis. Meanwhile, the DNA-binding also causes cell cycle arrest in the radiation-sensitive G2/M phase by the up-regulation of phosphorylated checkpoint kinase 1 (p-Chk1) expression. Furthermore, under X-ray irradiation, Pt STNA as radiosensitizer possesses a strong X-ray attenuation ability to deposit more energy, thus elevating the level of reactive oxygen species (ROS) to amplify the cell-killing effect of radiotherapy in the G2/M phase with increased DNA damage. As a result, Pt STNA exhibits significant synergistic therapeutic effects in chemoradiotherapy with no adverse effects in vitro and in vivo. Overall, we present a novel self-targeting nano-assembly strategy based on widely used Pt drugs for synergistic chemotherapy and radiation sensitization of HCC treatment.

Magnetite and bismuth sulfide Janus heterostructures as radiosensitizers for in vivo enhanced radiotherapy in breast cancer

Janus heterostructures based on bimetallic nanoparticles have emerged as effective radiosensitizers owing to their radiosensitization capabilities in cancer cells. In this context, this study aims at developing a novel bimetallic nanoradiosensitizer, Bi₂S₃-Fe₃O₄, to enhance tumor accumulation and promote radiation-induced DNA damage while reducing adverse effects. Due to the presence of both iron oxide and bismuth sulfide metallic nanoparticles in these newly developed nanoparticle, strong radiosensitizing capacity is anticipated through the generation of reactive oxygen species (ROS) to induce DNA damage under X-Ray irradiation. To improve blood circulation time, biocompatibility, colloidal stability, and tuning surface functionalization, the surface of Bi₂S₃-Fe₃O₄ bimetallic nanoparticles was coated with bovine serum albumin (BSA). Moreover, to achieve higher cellular uptake and efficient tumor site specificity, folic acid (FA) as a targeting moiety was conjugated onto the bimetallic nanoparticles, termed Bi₂S₃@BSA-Fe₃O₄-FA. Biocompatibility, safety, radiation-induced DNA damage by ROS activation and generation, and radiosensitizing ability were confirmed via in vitro and in vivo assays. The administration of Bi₂S₃@BSA-Fe₃O₄-FA in 4T1 breast cancer murine model upon X-ray radiation revealed highly effective tumor eradication without causing any mortality or severe toxicity in healthy tissues. These findings offer compelling evidence for the potential capability of Bi₂S₃@BSA-Fe₃O₄-FA as an ideal nanoparticle for radiation-induced cancer therapy and open interesting avenues of future research in this area.

X-ray triggered pea-shaped LuAG:Mn/Ca nano-scintillators and their applications for photodynamic therapy

Photodynamic therapy (PDT) is a new minimally invasive technology for disease diagnosis and treatment. However, the biological tissue attenuation of visible light renders the depth of its penetration in tissues quite modest, which significantly restricts its therapeutic applicability. Therefore, it is an essential but yet a difficult task to enhance the X-ray sensitization impact while concurrently limiting the tissue scattering by the rational design of novel biological vectors. Herein, a novel Lu3Al5O12:Mn/Ca-Ce6@SiO2 nanoparticle system (LAMCCS) based on a pea-shaped LuAG:Mn/Ca nano-scintillator (LAMC) activating photosensitizer agent (Ce6) was designed. Due to the high radiosensitization of LAMC nano-scintillators and efficient energy conversion efficiency between LAMC and Ce6, more singlet oxygen (1O2) could be generated to efficiently damage DNA fragments and reveal a good effect of inhibiting the long-term proliferation of tumor cells in vitro. Significantly, synergistic therapy with PDT/radiotherapy (RT) and from LAMCCS nanocomposites may still maintain a high tumor growth inhibition rate of 72% than single RT of 10% in vivo. Owing to their excellent ability for X-ray sensitization and energy conversion, LAMCCS nanocomposites may have significant tumor growth suppression rates under lower X-ray dose irradiation due to their outstanding X-ray sensitization and energy conversion capabilities, which may open up a new avenue for the advancement of cancer therapy.

Hyperthermia combined with immune checkpoint inhibitor therapy: Synergistic sensitization and clinical outcomes

BACKGROUND

Within the field of oncotherapy, research interest regarding immunotherapy has risen to the point that it is now seen as a key application. However, inherent disadvantages of immune checkpoint inhibitors (ICIs), such as their low response rates and immune-related adverse events (irAEs), currently restrict their clinical application. Were these disadvantages to be overcome, more patients could derive prolonged benefits from ICIs. At present, many basic experiments and clinical studies using hyperthermia combined with ICI treatment (HIT) have been performed and shown the potential to address the above challenges. Therefore, this review extensively summarizes the knowledge and progress of HIT for analysis and discusses the effect and feasibility.

METHODS

In this review, we explored the PubMed and clinicaltrials.gov databases, with regard to the searching terms "immune checkpoint inhibitor, immunotherapy, hyperthermia, ablation, photothermal therapy".

RESULTS

By reviewing the literature, we analyzed how hyperthermia influences tumor immunology and improves the efficacy of ICI. Hyperthermia can trigger a series of multifactorial molecular cascade reactions between tumors and immunization and can significantly induce cytological modifications within the tumor microenvironment (TME). The pharmacological potency of ICIs can be enhanced greatly through the immunomodulatory amelioration of immunosuppression, and the activation of immunostimulation. Emerging clinical trials outcome regarding HIT have verified and enriched the theoretical foundation of synergistic sensitization.

CONCLUSION

HIT research is now starting to transition from preclinical studies to clinical investigations. Several HIT sensitization mechanisms have been reflected and demonstrated as significant survival benefits for patients through pioneering clinical trials. Further studies into the theoretical basis and practical standards of HIT, combined with larger-scale clinical studies involving more cancer types, will be necessary for the future.

Research trends in biomedical applications of two-dimensional nanomaterials over the last decade - A bibliometric analysis

Two-dimensional (2D) nanomaterials with versatile properties have been widely applied in the field of biomedicine. Despite various studies having reviewed the development of biomedical 2D nanomaterials, there is a lack of a study that objectively summarizes and analyzes the research trend of this important field. Here, we employ a series of bibliometric methods to identify the development of the 2D nanomaterial-related biomedical field during the past 10 years from a holistic point of view. First, the annual publication/citation growth, country/institute/author distribution, referenced sources, and research hotspots are identified. Thereafter, based on the objectively identified research hotspots, the contributions of 2D nanomaterials to the various biomedical subfields, including those of biosensing, imaging/therapy, antibacterial treatment, and tissue engineering are carefully explored, by considering the intrinsic properties of the nanomaterials. Finally, prospects and challenges have been discussed to shed light on the future development and clinical translation of 2D nanomaterials. This review provides a novel perspective to identify and further promote the development of 2D nanomaterials in biomedical research.

Catalytic radiosensitization: Insights from materials physicochemistry

Radiotherapy is indispensable in clinical cancer treatment, but because both tumor and normal tissues have similar sensitivity to X-rays, their clinical curative effect is intrinsically limited. Advanced nanomaterials and nanotechnologies have been developed for radiotherapy sensitization, typically employing high atomic number (high-Z) materials to enhance the energy deposition of X-rays in tumor tissues, but the efficiency is largely limited by the toxicity of heavy metals. A new and promising approach for radiosensitization is catalytic radiosensitization, which takes advantage of the catalytic activity of nanomaterials triggered by radiation. The efficiency of catalytic radiosensitization can be greatly enhanced by electron modulation and energy conversion of nanocatalysts upon X-ray irradiation, further enhancing the clinical curative effect. In this review, we highlight the challenges and opportunities in cancer radiosensitization, discuss novel approaches to catalytic radiosensitization, and finally describe the development of catalytic radiosensitization based on an in-depth understanding of radio-nano interactions and catalysis-biological interactions.

Biocompatible Tantalum Nanoparticles as Radiosensitizers for Enhancing Therapy Efficacy in Primary Tumor and Metastatic Sentinel Lymph Nodes

Metastasis of breast carcinoma is commonly realized through lymphatic circulation, which seriously threatens the lives of breast cancer patients. Therefore, efficient therapy for both primary tumor and metastatic sentinel lymph nodes (SLNs) is highly desired to inhibit cancer growth and metastasis. During breast cancer treatment, radiotherapy (RT) is a common clinical method. However, the efficacy of RT is decreased by the radioresistance to a hypoxic microenvironment and inevitable side effects for healthy issues at high radiation doses. Considering the above-mentioned, we provide high biocompatible poly(vinylpyrrolidone) coated Ta nanoparticles (Ta@PVP NPs) for photothermal therapy (PTT) assisted RT for primary tumor and metastatic SLNs. On the one hand, for primary tumor treatment, Ta@PVP NPs with a high X-ray mass attenuation coefficient (4.30 cm²/kg at 100 keV) can deposit high radiation doses within tumors. On the other hand, for metastatic SLNs treatment, the effective delivery of Ta@PVP NPs from the primary tumor into SLNs is monitored by computed tomography and photoacoustic imaging, which greatly benefit the prognosis and treatment for metastatic SLNs. Moreover, Ta@PVP NPs-mediated PTT could enhance the RT effect, and immunogenic cell death caused by RT/PTT could induce an immune response to improve the therapeutic effect of metastatic SLNs. This study not only explores the potential of Ta@PVP NPs as effective radiosensitizers and photothermal agents for combined RT and PTT but also offers an efficient strategy to cure both primary tumor and metastatic SLNs in breast carcinoma.

PVP-Modified Multifunctional Bi2WO6 Nanosheets for Enhanced CT Imaging and Cancer Radiotherapy

Malignant tumors are one of the main causes of human death. The clinical treatment of malignant tumors is usually surgery, chemotherapy, radiotherapy, and so forth. Radiotherapy, as a traditional and effective treatment method for cancer, is widely used in clinical practice, but the radiation resistance of tumor cells and the toxic side effects to normal cells are still the Achilles heel of radiotherapy. Multifunctional inorganic high-atom nanomaterials are expected to enhance the effect of tumor radiotherapy. Tungsten and bismuth, which contain elements with high atomic coefficients, have strong X-ray energy attenuation capability. We synthesized Bi₂WO₆ nanosheets (NSs) using a hydrothermal synthesis method and modified polyvinylpyrrolidone (PVP) on their surface to make them more stable. PVP-Bi₂WO₆ NSs have a variety of effects after absorbing X-rays (such as the photoelectric effect and Compton effect) and release a variety of particles such as photoelectrons, Compton electrons, auger electrons, and so forth, which can react with organic molecules or water in cells, generate a large number of free radicals, and promote cell apoptosis, thereby improving the effect of radiotherapy. We show through γ-H2AX and DCFH-DA probe analysis experiments that PVP-Bi₂WO₆ NSs can effectively increase cell DNA damage and reactive oxygen species formation under X-ray irradiation. Clone formation analysis showed that PVP-Bi₂WO₆ NSs can effectively suppress cell colony formation under X-ray irradiation. These versatile functions endow PVP-Bi₂WO₆ NSs with enhanced radiotherapy efficacy in animal models. In addition, PVP-Bi₂WO₆ NSs can also be used as contrast agents for X-ray computed tomography (CT) imaging with obvious effects. Therefore, PVP-Bi₂WO₆ NSs can be used as CT imaging contrast agents and tumor radiotherapy sensitizers and have potential medical applications.

PEIGel: A biocompatible and injectable scaffold with innate immune adjuvanticity for synergized local immunotherapy

Intratumoral immunotherapeutic hydrogel administration is emerging as an effective method for inducing a durable and robust antitumor immune response. However, scaffold hydrogels that can synergize with the loaded drugs, thus potentiating therapeutic efficacy, are limited. Here, we report a ternary hydrogel composed of polyvinyl alcohol (PVA), polyethylenimine (PEI)‒a cationic polymer with potential immunoactivation effects, and magnesium ions‒a stimulator of the adaptive immune response, which exhibits an intrinsic immunomodulation function of reversing the immunologically "cold" phenotype of a murine breast tumor to a "hot" phenotype by upregulating PD-L1 expression and promoting M1-like macrophage polarization. PEI hydrogel (PEIGel) encapsulating an immune checkpoint blockade (ICB) inhibitor‒anti-PD-L1 antibody (α-PDL1) exhibits synergistic effects resulting in elimination of primary tumors and remote metastases and prevention of tumor relapse after surgical resection. A preliminary mechanistic study revealed a probably hidden role of PEI in modulating the polyamine metabolism/catabolism of tumors to potentiate the immune adjuvant effect. These results deepen our understanding of the innate immune activation function of PEI and pave the way for harnessing PEI as an immune adjuvant for ICB therapy.

Two-dimensional nanomaterials for tumor microenvironment modulation and anticancer therapy

The development of two-dimensional (2D) nanomaterials for cancer therapy has attracted increasing attention due to their high specific surface area, unique ultrathin structure, electronic and photonic properties. For biomedical applications, investigations into the family of 2D materials have been sparked by graphene and its derivatives. Many 2D nanomaterials, including layered double hydroxides, transition metal dichalcogenides, nitrides and carbonitrides, black phosphorus nanosheets, and metal-organic framework nanosheets, are extensively explored as cancer theranostic platforms. In addition to the high drug loading, 2D nanomaterials are featured with improved physiological properties of drugs, prolonged blood circulation, and increased tumor accumulation and bioavailability. As a consequence, 2D nanomaterials have been widely examined in pre-clinical tumor therapy, particularly through the tumor microenvironment (TME) modulation. This review summarizes recent progresses in developing 2D nanomaterials for TME modulating-based cancer diagnosis and therapy. It is anticipated that this review will benefit researchers to obtain a deeper understanding of interactions between 2D nanomaterials and TME components and develop rational and reliable 2D nanomedicines for pre/clinical cancer theranostics.

Design of Smart Nanomedicines for Effective Cancer Treatment

Nanomedicine is a novel field of study that involves the use of nanomaterials to address challenges and issues that are associated with conventional therapeutics for cancer treatment including, but not limited to, low bioavailability, low water-solubility, narrow therapeutic window, nonspecific distribution, and multiple side effects of the drugs. Multiple strategies have been exploited to reduce the nonspecific distribution, and thus the side effect of the active pharmaceutical ingredients (API), including active and passive targeting strategies and externally controllable release of the therapeutic cargo. Site-specific release of the drug prevents it from impacting healthy cells, thereby significantly reducing side effects. API release triggers can be either externally applied, as in ultrasound-mediated activation, or induced by the tumor. To rationally design such nanomedicines, a thorough understanding of the differences between the tumor microenvironment versus that of healthy tissues must be pared with extensive knowledge of stimuli-responsive biomaterials. Herein, we describe the characteristics that differentiate tumor tissues from normal tissues. Then, we introduce smart materials that are commonly used for the development of smart nanomedicines to be triggered by stimuli such as changes in pH, temperature, and enzymatic activity. The most recent advances and their impact on the field of cancer therapy are further discussed.

Heterojunction Nanomedicine

Exogenous stimulation catalytic therapy has received enormous attention as it holds great promise to address global medical issues. However, the therapeutic effect of catalytic therapy is seriously restricted by the fast charge recombination and the limited utilization of exogenous stimulation by catalysts. In the past few decades, many strategies have been developed to overcome the above serious drawbacks, among which heterojunctions are the most widely used and promising strategy. This review attempts to summarize the recent progress in the rational design and fabrication of heterojunction nanomedicine, such as semiconductor-semiconductor heterojunctions (including type I, type II, type III, PN, and Z-scheme junctions) and semiconductor-metal heterojunctions (including Schottky, Ohmic, and localized surface plasmon resonance-mediated junctions). The catalytic mechanisms and properties of the above junction systems are also discussed in relation to biomedical applications, especially cancer treatment and sterilization. This review concludes with a summary of the challenges and some perspectives on future directions in this exciting and still evolving field of research.