Photothermal-triggered immunogenic nanotherapeutics for optimizing osteosarcoma therapy by synergizing innate and adaptive immunity

2D nanomaterials-based delivery systems and their potentials in anticancer synergistic photo-immunotherapy

As the field of cancer therapeutics evolves, integrating two-dimensional (2D) nanomaterials with photo-immunotherapy has emerged as a promising approach with significant potential to augment cancer treatment efficacy. These 2D nanomaterials include graphene-based 2D nanomaterials, 2D MXenes, 2D layered double hydroxides, black phosphorus nanosheets, 2D metal-organic frameworks, and 2D transition metal dichalcogenides. They exhibit high load capacities, multiple functionalization pathways, optimal biocompatibility, and physiological stability. Predominantly, they function as anti-tumor delivery systems, amalgamating diverse therapeutic modalities, most notably phototherapy and immunotherapy, and the former is a recognized non-invasive treatment modality, and the latter represents the most promising anti-cancer strategy presently accessible. Thus, integrating phototherapy and immunotherapy founded on 2D nanomaterials unveils a novel paradigm in the war against cancer. This review delineates the latest developments in 2D nanomaterials as delivery systems for synergistic photo-immunotherapy in cancer treatment. We elaborate on the burgeoning realm of photo-immunotherapy, exploring the interplay between phototherapy and enhanced immune cells, immune response modulation, or immunosuppressive tumor microenvironments. Notably, the strategies to augment photo-immunotherapy have also been discussed. Finally, we discuss the challenges and future perspectives of these 2D nanomaterials in photo-immunotherapy.

ATP-Responsive Manganese-Based Bacterial Materials Synergistically Activate the cGAS-STING Pathway for Tumor Immunotherapy

Stimulating the cyclic guanosine monophophate(GMP)-adenosine monophosphate (AMP) synthase (cGAS)-stimulator of interferon genes (STING) pathway is a crucial strategy by which bacteria activate the tumor immune system. However, the limited stimulation capability poses significant challenges in advancing bacterial immunotherapy. Here, an adenosine 5'-triphosphate (ATP)-responsive manganese (Mn)-based bacterial material (E. coli@PDMC-PEG (polyethylene glycol)) is engineered successfully, which exhibits an exceptional ability to synergistically activate the cGAS-STING pathway. In the tumor microenvironment, which is characterized by elevated ATP levels, this biohybrid material degrades, resulting in the release of divalent manganese ions (Mn2+) and subsequent bacteria exposure. This combination synergistically activates the cGAS-STING pathway, as Mn2+ enhances the sensitivity of cGAS to the extracellular DNA (eDNA) secreted by the bacteria. The results of the in vivo experiments demonstrate that the biohybrid materials E. coli@PDMC-PEG and VNP20009@PDMC-PEG effectively inhibit the growth of subcutaneous melanoma in mice and in situ liver cancer in rabbits. Valuable insights for the development of bacteria-based tumor immunotherapy are provided here.

A multifunctional biomimetic nanoplatform for image-guideded photothermal-ferroptotic synergistic osteosarcoma therapy

Much effort has been devoted to improving treatment efficiency for osteosarcoma (OS). However, most current approaches result in poor therapeutic responses, thus indicating the need for the development of other therapeutic options. This study developed a multifunctional nanoparticle, PDA-MOF-E-M, an aggregation of OS targeting, programmed death targeting, and near-infrared (NIR)-aided targeting. At the same time, a multifunctional nanoparticle that utilises Fe-MOFs to create a cellular iron-rich environment and erastin as a ferroptosis inducer while ensuring targeted delivery to OS cells through cell membrane encapsulation is presented. The combination of PDA-MOF-E-M and PTT increased intracellular ROS and LPO levels and induced ferroptosis-related protein expression. A PDA-based PTT combined with erastin showed significant synergistic therapeutic improvement in the anti-tumour efficiency of the nanoparticle in vitro and vivo. The multifunctional nanoparticle efficiently prevents the osteoclasia progression of OS xenograft bone tumors in vivo. Finally, this study provides guidance and a point of reference for clinical approaches to treating OS.

Biomaterials-Boosted Immunotherapy for Osteosarcoma

Osteosarcoma (OS) is a primary malignant bone tumor that emanates from mesenchymal cells, commonly found in the epiphyseal end of long bones. The highly recurrent and metastatic nature of OS poses significant challenges to the efficacy of treatment and negatively affects patient prognosis. Currently, available clinical treatment strategies primarily focus on maximizing tumor resection and reducing localized symptoms rather than the complete eradication of malignant tumor cells to achieve ideal outcomes. The biomaterials-boosted immunotherapy for OS is characterized by high effectiveness and a favorable safety profile. This therapeutic approach manipulates the tumor microenvironments at the cellular and molecular levels to impede tumor progression. This review delves into the mechanisms underlying the treatment of OS, emphasizing biomaterials-enhanced tumor immunity. Moreover, it summarizes the immune cell phenotype and tumor microenvironment regulation, along with the ability of immune checkpoint blockade to activate the autoimmune system. Gaining a profound comprehension of biomaterials-boosted OS immunotherapy is imperative to explore more efficacious immunotherapy protocols and treatment options in this setting.

Biomimetic bone-periosteum scaffold for spatiotemporal regulated innervated bone regeneration and therapy of osteosarcoma

The complexity of repairing large segment defects and eradicating residual tumor cell puts the osteosarcoma clinical management challenging. Current biomaterial design often overlooks the crucial role of precisely regulating innervation in bone regeneration. Here, we develop a Germanium Selenium (GeSe) co-doped polylactic acid (PLA) nanofiber membrane-coated tricalcium phosphate bioceramic scaffold (TCP-PLA/GeSe) that mimics the bone-periosteum structure. This biomimetic scaffold offers a dual functionality, combining piezoelectric and photothermal conversion capabilities while remaining biodegradable. When subjected to ultrasound irradiation, the US-electric stimulation of TCP-PLA/GeSe enables spatiotemporal control of neurogenic differentiation. This feature supports early innervation during bone formation, promoting early neurogenic differentiation of Schwann cells (SCs) by increasing intracellular Ca2+ and subsequently activating the PI3K-Akt and Ras signaling pathways. The biomimetic scaffold also demonstrates exceptional osteogenic differentiation potential under ultrasound irradiation. In rabbit model of large segment bone defects, the TCP-PLA/GeSe demonstrates promoted osteogenesis and nerve fibre ingrowth. The combined attributes of high photothermal conversion capacity and the sustained release of anti-tumor selenium from the TCP-PLA/GeSe enable the synergistic eradication of osteosarcoma both in vitro and in vivo. This strategy provides new insights on designing advanced biomaterials of repairing large segment bone defect and osteosarcoma.

Ti3C2 (MXene), an advanced carrier system: role in photothermal, photoacoustic, enhanced drugs delivery and biological activity in cancer therapy

In the realm of healthcare and the advancing field of medical sciences, the development of efficient drug delivery systems become an immense promise to cure several diseases. Despite considerable advancements in drug delivery systems, numerous challenges persist, necessitating further enhancements to optimize patient outcomes. Smart nano-carriers, for instance, 2D sheets nano-carriers are the recently emerging nanosheets that may garner attention for targeted delivery of bioactive compounds, drugs, and genes to kill cancer cells. Within these advancements, Ti3C2TX-MXene, characterized as a two-dimensional transition metal carbide, has surfaced as a prominent intelligent nanocarrier within nanomedicine. Its noteworthy characteristics facilitated it as an ideal nanocarrier for cancer therapy. In recent advancements in drug delivery research, Ti3C2TX-MXene 2D nanocarriers have been designed to release drugs in response to specific stimuli, guided by distinct physicochemical  parameters. This review emphasized the multifaceted role of Ti3C2TX-MXene as a potential carrier for delivering poorly hydrophilic drugs to cancer cells, facilitated by various polymer coatings. Furthermore, beyond drug delivery, this smart nanocarrier demonstrates utility in photoacoustic imaging and photothermal therapy, further highlighting its significant role in cellular mechanisms.

Engineering Bimetallic Polyphenol for Mild Photothermal Osteosarcoma Therapy and Immune Microenvironment Remodeling by Activating Pyroptosis and cGAS-STING Pathway

The immunosuppressive tumor microenvironment (ITME) of osteosarcoma (OS) poses a significant obstacle to the efficacy of existing immunotherapies. Despite the attempt of novel immune strategies such as immune checkpoint inhibitors and tumor vaccines, their effectiveness remains suboptimal due to the inherent difficulty in mitigating ITME simultaneously from both the tumor and immune system. The promotion of anti-tumor immunity through the induction of immunogenic cell death and activation of the cGAS-STING pathway has emerged as potential strategies to counter the ITME and stimulate systemic antitumor immune responses. Here, a bimetallic polyphenol-based nanoplatform (Mn/Fe-Gallate nanoparticles coated with tumor cell membranes is presented, MFG@TCM) which combines with mild photothermal therapy (PTT) for reversing ITME via simultaneously inducing pyroptosis in OS cells and activating the cGAS-STING pathway in dendritic cells (DCs). The immunostimulatory pathways, through the syngeneic effect, exerted a substantial positive impact on promoting the secretion of damage-associated molecular patterns (DAMPs) and proinflammatory cytokines, which favors remodeling the immune microenvironment. Consequently, effector T cells led to a notable antitumor immune response, effectively inhibiting the growth of both primary and distant tumors. This study proposes a new method for treating OS using mild PTT and immune mudulation, showing promise in overcoming current treatment limitations.

Advancements in Photothermal Therapy Using Near-Infrared Light for Bone Tumors

Bone tumors, particularly osteosarcoma, are prevalent among children and adolescents. This ailment has emerged as the second most frequent cause of cancer-related mortality in adolescents. Conventional treatment methods comprise extensive surgical resection, radiotherapy, and chemotherapy. Consequently, the management of bone tumors and bone regeneration poses significant clinical challenges. Photothermal tumor therapy has attracted considerable attention owing to its minimal invasiveness and high selectivity. However, key challenges have limited its widespread clinical use. Enhancing the tumor specificity of photosensitizers through targeting or localized activation holds potential for better outcomes with fewer adverse effects. Combinations with chemotherapies or immunotherapies also present avenues for improvement. In this review, we provide an overview of the most recent strategies aimed at overcoming the limitations of photothermal therapy (PTT), along with current research directions in the context of bone tumors, including (1) target strategies, (2) photothermal therapy combined with multiple therapies (immunotherapies, chemotherapies, and chemodynamic therapies, magnetic, and photodynamic therapies), and (3) bifunctional scaffolds for photothermal therapy and bone regeneration. We delve into the pros and cons of these combination methods and explore current research focal points. Lastly, we address the challenges and prospects of photothermal combination therapy.

Circulating immunotherapy strategy based on pyroptosis and STING pathway: Mn-loaded paclitaxel prodrug nanoplatform against tumor progression and metastasis

Immunotherapy has emerged as a promising strategy against tumors. However, its efficacy is limited by low immunogenicity, poor antigen presentation, and inadequate lymphocyte infiltration. Herein, we develop a nanoplatform (Mn-HSP) loaded with manganese ions (Mn2+) and paclitaxel (PTX) prodrug based on hyaluronic acid. PTX in Mn-HSP induces DNA damage and pyroptosis to release tumor-associated antigens (TAAs), enhancing tumor-specific adaptive immunity. Meanwhile, Mn2+ in Mn-HSP, together with PTX-induced DNA damage, activates the stimulator of interferon gene (STING) pathway to amplify innate immunity. Mn-HSP combines with adaptive and innate immunity, effectively enhancing the presentation of antigen-presenting cells (APCs) and promoting tumor infiltration of cytotoxic T lymphocytes (CTLs). In turn, the granzyme B (GZMB) secreted by CTLs triggers pyroptosis again, thereby establishing a "circulating immunotherapy" against tumors. Our results demonstrate that Mn-HSP efficiently inhibits primary breast tumors, as well as rechallenge tumors and lung metastasis in vivo. Therefore, the circulating immunotherapy that combines pyroptosis mediated adaptive immunity and STING pathway amplified innate immunity provides a novel strategy for enhancing tumor immunotherapy.

Lung metastasis-Harnessed in-Situ adherent porous organic nanosponge-mediated antigen capture for A self-cascaded detained dendritic cells and T cell infiltration

The infiltration of cytotoxic T lymphocytes promises to suppress the most irresistible metastatic tumor for immunotherapy, yet immune privilege and low immunogenic responses in these aggressive clusters often restrict lymphocyte recruitment. Here, an in situ adherent porous organic nanosponge (APON) doubles as organ selection agent and antigen captor to overcome immune privilege is developed. With selective organ targeting, the geometric effect of APON composed of disc catechol-functionalized covalent organic framework (COF) boosts the drug delivery to lung metastases. Along with a self-cascaded immune therapy, the therapeutic agents promote tumor release of damage-associated molecular patterns (DAMPs), and then, in situ deposition of gels to capture these antigens. Furthermore, APON with catechol analogs functions as a reservoir of antigens and delivers autologous DAMPs to detain dendritic cells, resulting in a sustained enhancement of immunity. This disc sponges (APON) at lung metastasis as antigen reservoirs and immune modulators effectively suppress the tumor in 60 days and enhanced the survival rate.

Efficient TNBC immunotherapy by dual reprogramming tumor-infiltrating dendritic cells and tumor-associated macrophages with stimulus-responsive miR155 nanocomplexes

Triple negative breast cancer (TNBC) remains to be a formidable adversary with high mortality and unfavorable prognosis. Tumor microenvironment comprises of various constituents, among them, tumor infiltrating dendritic cells (TIDCs) and tumor-associated macrophages (TAMs) which have been recognized as pivotal factors responsible for mediating immune responses. Overcoming the refractory properties of TIDCs and TAMs is critical for inducing a robust and sustained immune response against cancer cells. In this study, pH/ROS-responsive microRNA-155 (miR155) nanocomplexes (MiR@PCPmP NPs) were developed to reprogram TIDCs and TAMs for efficient TNBC immunotherapy. This nanoplatform was based on a pH/ROS cleavable copolymer of poly(ethylene glycol)-carboxydimethyl maleate-poly(ethyleneimine)-peroxalate ester-poly(ε-caprolactone) grafted with mannose moieties (PEG-CDM-PEI[Man]-ox-PCL) which self-assembled with miRNA to form nanocomplexes. In the tumor microenvironment, the nanocomplexes showed selective cellular uptake by TIDCs and TAMs through PEG detachment and mannose exposure, followed by efficient endosomal escape, cytosolic miR155 release, and the dual-reprogramming of TIDCs and TAMs. Our results showed that MiR@PCPmP NPs significantly improved antitumor immune responses with highly infiltrating CD8+ T cells while restraining immunosuppressive components in 4T1 tumor-bearing mice. Furthermore, the nanoparticles effectively suppressed both primary tumors and pulmonary metastatic nodules without obvious systemic toxicity. This research highlights the potential of dual-reprogramming of TIDCs and TAMs with the miR155 nanocomplexes as a promising strategy for TNBC immunotherapy, with potential for translation to other cancers with a similar microenvironment.

Application of advanced biomaterials in photothermal therapy for malignant bone tumors

Malignant bone tumors are characterized by severe disability rate, mortality rate, and heavy recurrence rate owing to the complex pathogenesis and insidious disease progression, which seriously affect the terminal quality of patients' lives. Photothermal therapy (PTT) has emerged as an attractive adjunctive treatment offering prominent hyperthermal therapeutic effects to enhance the effectiveness of surgical treatment and avoid recurrence. Simultaneously, various advanced biomaterials with photothermal capacity are currently created to address malignant bone tumors, performing distinctive biological functions, including nanomaterials, bioceramics (BC), polymers, and hydrogels et al. Furthermore, PTT-related combination therapeutic strategies can provide more significant curative benefits by reducing drug toxicity, improving tumor-killing efficiency, stimulating anti-cancer immunity, and improving immune sensitivity relative to monotherapy, even in complex tumor microenvironments (TME). This review summarizes the current advanced biomaterials applicable in PTT and relevant combination therapies on malignant bone tumors for the first time. The multiple choices of advanced biomaterials, treatment methods, and new prospects for future research in treating malignant bone tumors with PTT are generalized to provide guidance. Malignant bone tumors seriously affect the terminal quality of patients' lives. Photothermal therapy (PTT) has emerged as an attractive adjunctive treatment enhancing the effectiveness of surgical treatment and avoiding recurrence. In this review, advanced biomaterials applicable in the PTT of malignant bone tumors and their distinctive biological functions are comprehensively summarized for the first time. Simultaneously, multiple PTT-related combination therapeutic strategies are classified to optimize practical clinical issues, contributing to the selection of biomaterials, therapeutic alternatives, and research perspectives for the adjuvant treatment of malignant bone tumors with PTT in the future.

Subtractive Nanopore Engineered MXene Photonic Nanomedicine with Enhanced Capability of Photothermia and Drug Delivery for Synergistic Treatment of Osteosarcoma

Two-dimensional (2D) nanomaterials as drug carriers and photosensitizers have emerged as a promising antitumor strategy. However, our understanding of 2D antitumor nanomaterials is limited to intrinsic properties or additive modification of different materials. Subtractive structural engineering of 2D nanomaterials for better antitumor efficacy is largely overlooked. Here, subtractively engineered 2D MXenes with uniformly distributed nanopores are synthesized. The nanoporous defects endowed MXene with enhanced surface plasmon resonance effect for better optical absorbance performance and strong exciton-phonon coupling for higher photothermal conversion efficiency. In addition, porous structure improves the binding ability between drug and unsaturated bonds, thus promoting drug-loading capacity and reducing uncontrolled drug release. Furthermore, the porous structure provides adhesion sites for filopodia, thereby promoting the cellular internalization of the drug. Clinically, osteosarcoma is the most common bone malignancy routinely treated with doxorubicin-based chemotherapy. There have been no significant treatment advances in the past decade. As a proof-of-concept, nanoporous MXene loaded with doxorubicin is developed for treating human osteosarcoma cells. The porous MXene platform results in a higher amount of doxorubicin-loading, faster near-infrared (NIR)-controlled doxorubicin release, higher photothermal efficacy under NIR irradiation, and increased cell adhesion and internalization. This facile method pioneers a new paradigm for enhancing 2D material functions and is attractive for tumor treatment.

Tissue adhesive indocyanine green-locking granular gel-mediated photothermal therapy combined with checkpoint inhibitor for preventing postsurgical recurrence and metastasis of colorectal cancer

Developing effective therapy to inhibit postoperative recurrence and metastasis of colorectal cancer (CRC) is challenging and significant to reduce mortality and morbidity. Here, a granular hydrogel, assembled from gelatin microgels by dialdehyde starch and interpenetrated with in situ polymerized poly(sulfobetaine methacrylate-co-N-isopropylacrylamide) (P(SBMA-co-NIPAM)), is prepared to load and lock Food and Drug Administration (FDA)-approved indocyanine green (ICG) with definite photothermal function and biosafety for photothermal therapy (PTT) combining with checkpoint inhibitor. The presence of P(SBMA-co-NIPAM) endows granular hydrogel with high retention to water-soluble ICG, preventing easy diffusion and rapid scavenging of ICG. The ICG-locking granular hydrogel can be spread and adhered onto the surgery site at wet state in vivo, exerting a persistent and stable PTT effect. Combined with αPD-L1 treatment, ICG-locking granular hydrogel-mediated PTT can eradicate postsurgery residual and metastatic tumors, and prevent long-term tumor recurrence. Further mechanistic studies indicate that combination treatment effectively promotes dendritic cells maturation in lymph nodes, enhances the number and infiltration of CD8+ T and CD4+ T cells in tumor tissue, and improves memory T cell number in spleen, thus activating the antitumor immune response. Overall, ICG-locking gel-mediated PTT is expected to exhibit broad clinical applications in postoperative treatment of cancers, like CRC.

A sequential scheme including PTT and 2'3'-cGAMP/CQ-LP reveals the antitumor immune function of PTT through the type I interferon pathway

Photothermal therapy (PTT) is a promising antitumor treatment that is easy to implement, minimally invasive, and precisely controllable, and evokes strong antitumor immunity. We believe that a thorough elucidation of its underlying antitumor immune mechanisms would contribute to the rational design of combination treatments with other antitumor strategies and consequently potentiate clinical use. In this study, PTT using indocyanine green (ICG) induced STING-dependent type I interferon (IFN) production in macrophages (RAW264.7 and bone marrow-derived macrophages (BMDMs)), as proven by the use of a STING inhibitor (C178), and triggered STING-independent type I IFN generation in tumor cells (CT26 and 4T1), which was inhibited by DNase pretreatment. A novel liposome coloaded with the STING agonist 2'3'-cGAMP (cGAMP) and chloroquine (CQ) was constructed to achieve synergistic effect with PTT, in which CQ increased cGAMP entrapment efficiency and prevented STING degradation after IFN signaling activation. The sequential combination treatment caused a significant increase in tumor cell apoptosis, probably due to interferon stimulating gene products 15 and 54 (ISG15 and ISG 54), and achieved a more striking antitumor inhibition effect in the CT26 tumor model than the 4T1 model, likely due to higher STAT1 expression and consequently more intense IFN signal transduction. In the tumor microenvironment, the combination treatment increased infiltrating CD8+T cells (4-fold) and M1-like TAMs (10-fold), and decreased M-MDSCs (over 2-fold) and M2-like TAMs (over 4-fold). Above all, in-depth exploration of the antitumor mechanism of PTT provides guidance for selecting sensitive tumor models and designing reasonable clinical schemes.

A tumor microenvironment-activatable nanoplatform with phycocyanin-assisted in-situ nanoagent generation for synergistic treatment of colorectal cancer

The in-situ generation of therapeutic agents in targeted lesions is promising for revolutionizing oncotherapy but is limited by the low production efficiency. Given the specific tumor microenvironment (TME) of colorectal cancer (CRC), i.e., mild acidity, overexpressed H2O2, glutathione (GSH) and H2S, we develop phycocyanin (PC) encapsulated PZTC/SS/HA nanocapsules (NCs) for TME-responsive, protein-assisted "turn-on'' therapy of CRC. The NCs are prepared by sequentially assembling Cu2+-tannic acid (TA) coordination shell, disulfide bond-bearing cross-linker, and hyaluronic acid (HA) on the sacrificial template ZIF-8, thus achieving pH-, GSH-responsiveness, and tumor targeting capability, respectively. Once reaching the CRC sites, the NCs can quickly disintegrate and release Cu2+ and PC, accompanied by subsequent endogenous H2S-triggered generation of copper sulfide (CuS). Significantly, the intracellular sulfidation process can be accelerated by PC, thereby enabling efficient photothermal therapy (PTT) under NIR-Ⅱ laser. Besides, Cu2+-associated chemodynamic therapy (CDT) can be simultaneously activated and enhanced by PTT-induced local hyperthermia and disulfide bond-induced GSH consumption. This CRC-targeted and TME-activated synergistic PTT/CDT strategy displays high therapeutic efficacy both in vitro and in vivo, which can open up a new avenue for biomolecule-assisted in-situ nanoagent generation and effective TME-responsive synergistic treatment of CRC.

Natural Chlorogenic Acid Planted Nanohybrids with Steerable Hyperthermia for Osteosarcoma Suppression and Bone Regeneration

Surgical resection is the most common approach for the treatment of osteosarcoma. However, two major complications, including residual tumor cells and large bone defects, often arise from the surgical resection of osteosarcoma. Discovering new strategies for programmatically solving the two above-mentioned puzzles has become a worldwide challenge. Herein, a novel one-step strategy is reported for natural phenolic acid planted nanohybrids with desired physicochemical properties and steerable photothermal effects for efficacious osteosarcoma suppression and bone healing. Nanohybrids are prepared based on the self-assembly of chlorogenic acid and gold nanorods through robust Au-catechol interface actions, featuring precise nanostructures, great water solubility, good stability, and adjustable hyperthermia generating capacity. As expected, on the one hand, these integrated nanohybrids can severely trigger apoptosis and suppress tumor growth with strong hyperthermia. On the other hand, with controllable mild NIR irradiation, the nanohybrids promote the expression of heat shock proteins and induce prominent osteogenic differentiation. This work initiates a brand-new strategy for assisting osteosarcoma surgical excision to resolve the blockage of residual tumor cells elimination and bone regeneration.

Regulating Photosensitizer Metabolism with DNAzyme-Loaded Nanoparticles for Amplified Mitochondria-Targeting Photodynamic Immunotherapy

Mitochondria-specific photosensitizer accumulation is highly recommended for photodynamic therapy and mitochondrial DNA (mtDNA) oxidative damage-based innate immunotherapy but remains challenging. 5-Aminolevulinic acid (ALA), precursor of photosensitizer protoporphyrin IX (PpIX), can induce the exclusive biosynthesis of PpIX in mitochondria. Nevertheless, its photodynamic effect is limited by the intracellular biotransformation of ALA in tumors. Here, we report a photosensitizer metabolism-regulating strategy using ALA/DNAzyme-co-loaded nanoparticles (ALA&Dz@ZIF-PEG) for mitochondria-targeting photodynamic immunotherapy. The zeolitic imidazolate framework (ZIF-8) nanoparticles can be disassembled and release large amounts of zinc ions (Zn2+) within tumor cells. Notably, Zn2+ can relieve tumor hypoxia for promoting the conversion of ALA to PpIX. Moreover, Zn2+ acts as a cofactor of rationally designed DNAzyme for silencing excessive ferrochelatase (FECH; which catalyzes PpIX into photoinactive Heme), cooperatively promoting the exclusive accumulation of PpIX in mitochondria via the "open source and reduced expenditure" manner. Subsequently, the photodynamic effects derived from PpIX lead to the damage and release of mtDNA and activate the innate immune response. In addition, the released Zn2+ further enhances the mtDNA/cGAS-STING pathway mediated innate immunity. The ALA&Dz@ZIF-PEG system induced 3 times more PpIX accumulation than ALA-loaded liposome, significantly enhancing tumor regression in xenograft tumor models.

Biomaterial-enabled therapeutic modulation of cGAS-STING signaling for enhancing antitumor immunity

cGAS-STING signaling is a central component in the therapeutic action of most existing cancer therapies. The accumulated knowledge of tumor immunoregulatory network in recent years has spurred the development of cGAS-STING agonists for tumor treatment as an effective immunotherapeutic strategy. However, the clinical translation of these agonists is thus far unsatisfactory because of the low immunostimulatory efficacy and unrestricted side effects under clinically relevant conditions. Interestingly, the rational integration of biomaterial technology offers a promising approach to overcome these limitations for more effective and safer cGAS-STING-mediated tumor therapy. Herein, we first outline the cGAS-STING signaling axis and generally discuss its association with tumors. We then symmetrically summarize the recent progress in those biomaterial-based cGAS-STING agonism strategies to generate robust antitumor immunity, categorized by the chemical nature of those cGAS-STING stimulants and carrier substrates. Finally, a perspective is provided to discuss the existing challenges and potential opportunities in cGAS-STING modulation for tumor therapy.

Multifunctional Nanoparticles Precisely Reprogram the Tumor Microenvironment and Potentiate Antitumor Immunotherapy after Near-Infrared-II Light-Mediated Photothermal Therapy

Mild-temperature photothermal therapy (mild PTT) is a safe and efficient antitumor therapy. However, mild PTT alone usually fails to activate the immune response and prevent tumor metastasis. Herein, a photothermal agent, copper sulfide@ovalbumin (CuS@OVA), with an effective PTT effect in the second near-infrared (NIR-II) window, is developed. CuS@OVA can optimize the tumor microenvironment (TME) and evoke an adaptive immune response. Copper ions are released in the acidic TME to promote the M1 polarization of tumor-associated macrophages. The model antigen OVA not only acts as a scaffold for nanoparticle growth but also promotes the maturation of dendritic cells, which primes naive T cells to stimulate adaptive immunity. CuS@OVA augments the antitumor efficiency of the immune checkpoint blockade (ICB) in vivo, which suppresses tumor growth and metastasis in a mouse melanoma model. The proposed therapeutic platform, CuS@OVA nanoparticles, may be a potential adjuvant for optimizing the TME and improving the efficiency of ICB as well as other antitumor immunotherapies. STATEMENT OF SIGNIFICANCE: Mild-temperature photothermal therapy (mild PTT) is a safe and efficient antitumor therapy, but usually fails to activate the immune response and prevent tumor metastasis. Herein, we develop a photothermal agent, copper sulfide@ovalbumin (CuS@OVA), with an excellent PTT effect in the second near-infrared (NIR-II) window. CuS@OVA can optimize the tumor microenvironment (TME) and evoke an adaptive immune response by promoting the M1 polarization of tumor-associated macrophages and the maturation of dendritic cells. CuS@OVA augments the antitumor efficiency of the immune checkpoint blockade (ICB) in vivo, suppressing tumor growth and metastasis. The platform may be a potential adjuvant for optimizing the TME and improving the efficiency of ICB as well as other antitumor immunotherapies.

Biomaterials Facilitating Dendritic Cell-Mediated Cancer Immunotherapy

Dendritic cell (DC)-based cancer immunotherapy has exhibited remarkable clinical prospects because DCs play a central role in initiating and regulating adaptive immune responses. However, the application of traditional DC-mediated immunotherapy is limited due to insufficient antigen delivery, inadequate antigen presentation, and high levels of immunosuppression. To address these challenges, engineered biomaterials have been exploited to enhance DC-mediated immunotherapeutic effects. In this review, vital principal components that can enhance DC-mediated immunotherapeutic effects are first introduced. The parameters considered in the rational design of biomaterials, including targeting modifications, size, shape, surface, and mechanical properties, which can affect biomaterial optimization of DC functions, are further summarized. Moreover, recent applications of various engineered biomaterials in the field of DC-mediated immunotherapy are reviewed, including those serve as immune component delivery platforms, remodel the tumor microenvironment, and synergistically enhance the effects of other antitumor therapies. Overall, the present review comprehensively and systematically summarizes biomaterials related to the promotion of DC functions; and specifically focuses on the recent advances in biomaterial designs for DC activation to eradicate tumors. The challenges and opportunities of treatment strategies designed to amplify DCs via the application of biomaterials are discussed with the aim of inspiring the clinical translation of future DC-mediated cancer immunotherapies.

Manganese-Based Tumor Immunotherapy

As an essential micronutrient, manganese (Mn) participates in various physiological processes and plays important roles in host immune system, hematopoiesis, endocrine function, and oxidative stress regulation. Mn-based nanoparticles are considered to be biocompatible and show versatile applications in nanomedicine, in particular utilized in tumor immunotherapy in the following ways: 1) acting as a biocompatible nanocarrier to deliver immunotherapeutic agents for tumor immunotherapy; 2) serving as an adjuvant to regulate tumor immune microenvironment and enhance immunotherapy; 3) activating host's immune system through the cGAS-STING pathway to trigger tumor immunotherapy; 4) real-time monitoring tumor immunotherapy effect by magnetic resonance imaging (MRI) since Mn²⁺ ions are ideal MRI contrast agent which can significantly enhance the T₁ -weighted MRI signal after binding to proteins. This comprehensive review focuses on the most recent progress of Mn-based nanoplatforms in tumor immunotherapy. The characteristics of Mn are first discussed to guide the design of Mn-based multifunctional nanoplatforms. Then the biomedical applications of Mn-based nanoplatforms, including immunotherapy alone, immunotherapy-involved multimodal synergistic therapy, and imaging-guided immunotherapy are discussed in detail. Finally, the challenges and future developments of Mn-based tumor immunotherapy are highlighted.

Photothermal "nano-dot" reactivate "immune-hot" for tumor treatment via reprogramming cancer cells metabolism

Cancer immunotherapy, despite its enormous application prospect, is trapped in the abnormal lactic acid metabolism of tumor cells that usually causes an immunosuppressive tumor microenvironment (ITM). Inducing immunogenic cell death (ICD) not only sensitizes cancer cells to carcer immunity, but also leads to a great increase in tumor-specific antigens. It improves tumor condition from "immune-cold" to "immune-hot". Herein, a near-infrared photothermal agent NR840 was developed and encapsulated into tumor-targeted polymer DSPE-PEG-cRGD and carried lactate oxidase (LOX) by electrostatic interaction, forming self-assembling "nano-dot" PLNR840 with high loading capacity for synergistic antitumor photo-immunotherapy. In this strategy, PLNR840 was swallowed by cancer cells, then dye NR840 was excited at 808 nm to generate heat inducing tumor cell necrosis, which further caused ICD. LOX could serve as a catalyst, reducing lactic acid efflux via regulation of cell metabolism. More importantly, the consumption of intratumoral lactic acid could substantially reverse ITM, including promoting the polarization of tumor-associated macrophages from M2 to M1 type, inhibiting the viability of regulatory T cells for sensitizing photothermal therapy (PTT). After the combination of αPD-L1 (programmed cell death protein ligand 1), PLNR840 restored CD8⁺ T-cell activity that thoroughly cleaned the pulmonary metastasis of breast cancer in 4T1 mouse model and cured hepatocellular carcinoma in Hepa1-6 mouse model. This study provided an effective PTT strategy to boost "immune-hot" and reprogrammed tumor metabolism for antitumor immunotherapy.

Roles of MXenes in biomedical applications: recent developments and prospects

....With the development of nanomedical technology, the application of various novel nanomaterials in the biomedical field has been greatly developed in recent years. MXenes, which are new inorganic nanomaterials with ultrathin atomic thickness, consist of layered transition metal carbides and nitrides or carbonitrides and have the general structural formula M_n+1X_nT_x (n = 1-3). Based on the unique structural features of MXenes, such as ultrathin atomic thickness and high specific surface area, and their excellent physicochemical properties, such as high photothermal conversion efficiency and antibacterial properties, MXenes have been widely applied in the biomedical field. This review systematically summarizes the application of MXene-based materials in biomedicine. The first section is a brief summary of their synthesis methods and surface modification strategies, which is followed by a focused overview and analysis of MXenes applications in biosensors, diagnosis, therapy, antibacterial agents, and implants, among other areas. We also review two popular research areas: wearable devices and immunotherapy. Finally, the difficulties and research progress in the clinical translation of MXene-based materials in biomedical applications are briefly discussed.

Managing the immune microenvironment of osteosarcoma: the outlook for osteosarcoma treatment

Osteosarcoma, with poor survival after metastasis, is considered the most common primary bone cancer in adolescents. Notwithstanding the efforts of researchers, its five-year survival rate has only shown limited improvement, suggesting that existing therapeutic strategies are insufficient to meet clinical needs. Notably, immunotherapy has shown certain advantages over traditional tumor treatments in inhibiting metastasis. Therefore, managing the immune microenvironment in osteosarcoma can provide novel and valuable insight into the multifaceted mechanisms underlying the heterogeneity and progression of the disease. Additionally, given the advances in nanomedicine, there exist many advanced nanoplatforms for enhanced osteosarcoma immunotherapy with satisfactory physiochemical characteristics. Here, we review the classification, characteristics, and functions of the key components of the immune microenvironment in osteosarcoma. This review also emphasizes the application, progress, and prospects of osteosarcoma immunotherapy and discusses several nanomedicine-based options to enhance the efficiency of osteosarcoma treatment. Furthermore, we examine the disadvantages of standard treatments and present future perspectives for osteosarcoma immunotherapy.

Endogenous/Exogenous Nanovaccines Synergistically Enhance Dendritic Cell-Mediated Tumor Immunotherapy

Traditional dendritic cell (DC)-mediated immunotherapy is usually suppressed by weak immunogenicity in tumors and generally leads to unsatisfactory outcomes. Synergistic exogenous/endogenous immunogenic activation can provide an alternative strategy for evoking a robust immune response by promoting DC activation. Herein, Ti₃ C₂ MXene-based nanoplatforms (termed MXP) are prepared with high-efficiency near-infrared photothermal conversion and immunocompetent loading capacity to form endogenous/exogenous nanovaccines. Specifically, the immunogenic cell death of tumor cells induced by the photothermal effects of the MXP can generate endogenous danger signals and antigens release to boost vaccination for DC maturation and antigen cross-presentation. In addition, MXP can deliver model antigen ovalbumin (OVA) and agonists (CpG-ODN) as an exogenous nanovaccine (MXP@OC), which further enhances DC activation. Importantly, the synergistic strategy of photothermal therapy and DC-mediated immunotherapy by MXP significantly eradicates tumors and enhances adaptive immunity. Hence, the present work provides a two-pronged strategy for improving immunogenicity and killing tumor cells to achieve a favorable outcome in tumor patients.

NIR responsive nanoenzymes via photothermal ablation and hypoxia reversal to potentiate the STING-dependent innate antitumor immunity

Despite advances in combined photothermal/immunotherapy of tumor, the therapeutic effect has been impaired due to hypoxic microenvironment and inadequate immune activation. Manganese ions directly activated the stimulator of interferon genes (STING) pathway and induced innate antitumor immunity. Herein, a near infrared light (NIR)-responsive nanoenzyme (PB-Mn/OVA NE) was constructed by doping manganese into the ovalbumin (OVA)-templated Prussian blue (PB) nanoparticles. The resultant PB-Mn/OVA NEs exhibited favorable catalase activity to produce oxygen, which was conducive to alleviate the tumor hypoxic microenvironment. Under 808 ​nm NIR irradiation, the PB-Mn/OVA NEs with outstanding photothermal conversion efficiency of 30% significantly destroyed tumor cells by inducing immunogenic cell death (ICD). Impressively, the PB-Mn/OVA NEs could activate the cGAS-STING pathway to promote the maturation and the antigen cross-presentation ability of dendritic cells (DCs), which further activated cytotoxic T lymphocytes and memory T lymphocytes. Overall, this work presents a powerful nanoenzyme formula to integrate photothermal ablation and hypoxic reversal for triggering robust innate and adaptive antitumor immune response.

Treat the "Untreatable" by a Photothermal Agent: Triggering Heat and Immunological Responses for Rabies Virus Inactivation

Rabies is a fatal neurological zoonotic disease caused by the rabies virus (RABV), and the approved post-exposure prophylaxis (PEP) procedure remains unavailable in areas with inadequate medical systems. Although strategies have been proposed for PEP and postinfection treatment (PIT), because of the complexity of the treatment procedures and the limited curative outcome, developing an effective treatment strategy remains a holy grail in rabies research. Herein, a facile approach is proposed involving photothermal therapy (PTT) and photothermally triggered immunological effects to realize effective PEP and PIT simultaneously. The designed photothermal agent (N⁺ TT-mCB nanoparticles) featured positively charged functional groups and high photo-to-heat efficiency, which are favorable for virus targeting and inactivation. The level of the virus at the site of infection in mice is significantly decreased upon treatment with orthotopic PTT, and the transfer of the virus to the brain is significantly inhibited. Furthermore, the survival ratio of the mice three days postinfection is increased by intracranial injection of N⁺ TT-mCB and laser irradiation. Overall, this work provides a platform for the effective treatment of RABV and opens a new avenue for future antiviral studies.

Functional two-dimensional MXenes as cancer theranostic agents

Recently, MXenes, as a kind of two-dimensional (2D) layered materials with exceptional performance, have become the research hotspots owing to their unique structural, electronic, and chemical properties. They have potential applications in electrochemical storage, photocatalysis, and biosensors. Furthermore, they have certain characteristics such as large surface area, favorable biocompatibility, and ideal mechanical properties, which can expand their applications in biomedical fields, especially in cancer therapy. To date, several researchers have explored the applications of MXenes in tumor elimination, which exhibited other fantastic properties of those 2D MXenes, such as efficient in vivo photothermal ablation, low phototoxicity, high biocompatibility, etc. In this review, the structures, properties, modifications, and preparation methods are introduced respectively. More importantly, the multifunctional platforms for cancer therapy based on MXenes nanosheets (NSs) are reviewed in detail, including single-modality and combined-modality cancer therapy. Finally, the prospects and challenges of MXenes are prospected and discussed. STATEMENT OF SIGNIFICANCE: In this review, the structures, properties, modifications, and preparation methods of MXenes nanomaterials are introduced, respectively. In addition, the preparation conditions and morphological characterizations of some common MXenes for therapeutic platforms are also summarized. More importantly, the practical applications of MXenes-based nanosheets are reviewed in detail, including drug delivery, biosensing, bioimaging, and multifunctional tumor therapy platforms. Finally, the future prospects and challenges of MXenes are prospected and discussed.

Robust Bioinspired MXene-Hemicellulose Composite Films with Excellent Electrical Conductivity for Multifunctional Electrode Applications

MXene-based structural materials with high mechanical robustness and excellent electrical conductivity are highly desirable for multifunctional applications. The incorporation of macromolecular polymers has been verified to be beneficial to alleviate the mechanical brittleness of pristine MXene films. However, the intercalation of a large amount of insulating macromolecules inevitably compromises their electrical conductivity. Inspired by wood, short-chained hemicellulose (xylo-oligosaccharide) acts as a molecular binder to bind adjacent MXene nanosheets together; this work shows that this can significantly enhance the mechanical properties without introducing a large number of insulating phases. As a result, MXene-hemicellulose films can integrate a high electrical conductivity (64,300 S m^-1) and a high mechanical strength (125 MPa) simultaneously, making them capable of being high-performance electrode materials for supercapacitors and humidity sensors. This work proposes an alternative method to manufacture robust MXene-based structural materials for multifunctional applications.

Thermal Properties of MXenes and Relevant Applications

The properties and applications of MXenes (a family of layered transition metal carbides, nitrides, and carbonitrides) have aroused enormous research interests for a decade since the successful synthesis of few-layer transition metal carbides in 2011. Though MXenes, as the building blocks, have already been applied in various fields (such as wearable electronics) owing to the distinctive optical, mechanical and electrical properties, their thermal stability and intrinsic thermal properties were less thoroughly investigated compared to other characteristics in early reports. The pioneering theoretical prediction of the thermoelectric nature of MXenes was performed in 2013 while the first experiment-based report concerning the degradation behavior of the 2D structure at elevated temperatures in a controlled atmosphere was published in 2015, followed by numerous discoveries regarding the thermal properties of MXenes. Herein, after a brief description of the synthesis, this Review summarized the latest insights into the thermal stability and thermophysical properties of MXenes, and further associated these unique properties with relevant applications by multiple examples. Finally, current hurdles and challenges in this field were provided along with some advices on potential research directions in the future.