Iron-doped carbon-based nanoparticles: emerging strategies in cancer therapeutics

Magnetite (Fe3O4) nanoparticles have been extensively used in noninvasive cancer treatment, for example, magnetic hyperthermia (MH) and chemodynamic therapy (CDT). However, how to achieve a highly efficient MH-CDT synergistic therapy based only on a single component of Fe3O4 still remains a challenge. Herein, hollow Fe3O4 mesocrystals (MCs) are constructed via a modified solvothermal method. Owing to the distinctive magnetic property of the mesocrystalline structure, Fe3O4 MCs show excellent magnetothermal conversion efficiency with a specific absorption rate of 722 w g-1 at a Fe concentration of 0.6 mg mL-1, much higher than that of Fe3O4 polycrystals (PCs). Moreover, Fe3O4 MCs also exhibit higher peroxidase-like activity than Fe3O4 PCs, which may be ascribed to the higher ratio of Fe2+/Fe3+ and more oxygen defects in the Fe3O4 MCs. Detailed in vivo results confirm that Fe3O4 MCs can instantly initiate CDT by producing the detrimental •OH, and such boosted reactive oxygen levels not only induces cell apoptosis but also reduces the expression of heat shock proteins, thus enabling low-temperature-mediated MH. More importantly, the in situ rising temperature resulted from MH in turn facilitates CDT, thus achieving a self-augmented synergistic effect between MH and CDT.

A biomimetic nanoplatform mediates hypoxia-adenosine axis disruption and PD-L1 knockout for enhanced MRI-guided chemodynamic-immunotherapy.

Hollow manganese dioxide/copper-doped carbon dot nanoplatform reshapes the tumor microenvironment to enhance the immune therapy response.

Graphitic carbon nitride/methyl pyrophaeophorbide a-copper/folate nanoconjugate for enhanced immunogenic death combined with PD-L1 immune checkpoint blockades.

Rationale: Melanoma remains a highly aggressive malignancy with limited effective therapies and frequent resistance to immune checkpoint blockade (ICB). Extracellular vesicles (EVs) represent a promising platform for RNA-based therapeutics, but their clinical translation is impeded by inefficient cargo loading and insufficient tumor-specific targeting. To address these limitations, we developed an engineered EV strategy integrating efficient miRNA packaging with tumor-targeting surface modifications to enhance therapeutic outcomes in melanoma.Methods: Engineered EVs (iEV-150) were generated by co-expressing miR-150-3p and Annexin A2 (ANXA2) in HEK293T cells, followed by surface modification with tumor-targeting iRGD peptides. Mechanistic insights were obtained using RNA sequencing, RNA immunoprecipitation (RIP), chromatin immunoprecipitation (ChIP), and luciferase reporter assays. Ferroptosis induction was evaluated through lipid peroxidation analysis, mitochondrial membrane potential assays, and transmission electron microscopy (TEM). Therapeutic efficacy and biodistribution were assessed in vivo using subcutaneous and metastatic melanoma mouse models. Immune modulation was examined by analyzing CD8⁺ T cell activation via flow cytometry in co-cultures of patient-derived CD8⁺ T cells and melanoma cells treated with iEV-150.Results: miR-150-3p was elevated in melanoma-derived EVs, and ANXA2 was identified as a key RNA-binding protein that selectively facilitated its loading into EVs. iEV-150 exhibited enhanced uptake by melanoma cells and improved tumor-specific accumulation in vivo. Mechanistically, iEV-150 suppressed NF2 expression, disrupted the NF2-LATS1 interaction, activated YAP signaling, and subsequently upregulated ferroptosis-related genes ACSL4 and CHAC1, thereby inducing ferroptosis through the NF2-Hippo-YAP axis. In addition to its direct anti-tumor effects, iEV-150 promoted CD8⁺ T cell infiltration and activation within the tumor microenvironment, and significantly enhanced the therapeutic efficacy of ICB in melanoma models.Conclusions: iEV-150 integrates ANXA2-mediated miRNA loading, tumor-specific targeting, ferroptosis induction, and immune microenvironment reprogramming. This engineered EV strategy provides an effective RNA-based therapeutic platform to overcome ICB resistance and enhance precision treatment in melanoma.

A carrier-free tri-component nanoreactor for multi-pronged synergistic cancer therapy

To overcome the limited efficacy of chemodynamic therapy (CDT) caused by insufficient hydrogen peroxide (H2O2) in the tumor microenvironment, we engineered a glutathione (GSH)-responsive multifunctional nanosystem, HCTG-C, based on hollow mesoporous organosilica nanoparticles. This system integrates tirapazamine (TPZ), glucose oxidase (GOx), in situ-synthesized copper sulfide (CuS), and CT2A glioma cell membrane coating to enable dual tumor-targeted therapy and self-imaging capabilities. The therapeutic mechanism relies on three synergistic cascades: (1) GOx-mediated glucose oxidation to deplete oxygen and generate H2O2, establishing a self-sustaining H2O2 supply; (2) GSH-triggered CuS conversion to Cu(I), amplifying Fenton-like reactions for efficient H2O2-to-reactive oxygen species conversion and ferroptosis induction; and (3) hypoxia-activated TPZ to exert cytotoxic effects, synergizing chemotherapy with CDT. Experimental results demonstrated that HCTG-C achieves real-time MRI monitoring via GSH depletion-driven Cu valence transitions, while its self-replenishing H2O2 and oxygen-activation mechanisms significantly enhance antitumor efficacy against CT2A glioma in vitro and in vivo. By innovatively combining H2O2 self-supply cascades, hypoxia-activated chemotherapy, and ferroptosis-driven CDT, this work presents a paradigm-shifting strategy for self-imaging-guided combinatorial therapy, advancing ferroptosis-based approaches for precision glioma treatment.

Immunotherapeutic efficacy of tumors based on immune checkpoint blockade (ICB) therapy is frequently limited by an immunosuppressive tumor microenvironment and cross-reactivity with normal tissues. Herein, we develop reactive oxygen species (ROS)-responsive nanocomplexes with the function of ROS production for delivery and triggered release of anti-mouse programmed death ligand 1 antibody (αPDL1) and glucose oxidase (GOx). GOx and αPDL1 were complexed with oligomerized (-)-epigallocatechin-3-O-gallate (OEGCG), which was followed by chelation with Fe3+ and coverage of the ROS-responsive block copolymer, POEGMA-b-PTKDOPA, consisting of poly(oligo(ethylene glycol)methacrylate) (POEGMA) and the block with thioketal bond-linked dopamine moieties (PTKDOPA) as the side chains. After intravenous injection, the nanocomplexes show prolonged circulation in the bloodstream with a half-life of 8.72 h and efficient tumor accumulation. At the tumor sites, GOx inside the nanocomplexes can produce H2O2 via oxidation of glucose for Fenton reaction to generate hydroxyl radicals (•OH) which further trigger the release of the protein cargos through ROS-responsive cleavage of thioketal bonds. The released GOx improves the production efficiency of •OH to kill cancer cells for release of tumor-associated antigens via chemodynamic therapy (CDT). The enhanced immunogenic cell death (ICD) can activate the immunosuppressive tumor microenvironment and improve the immunotherapy effect of the released αPDL1, which significantly suppresses primary and metastatic tumors. Thus, the nanocomplexes with Fenton reaction-triggered protein release show great potentials to improve the immunotherapeutic efficacy of ICB via combination with CDT.

Bimetallic nanoreactor mediates cascade amplification of oxidative stress for complementary chemodynamic-immunotherapy of tumor.

In clinical practice, the treatment of colon cancer is faced with the dilemma of metastasis and recurrence, which is related to immunosuppression and hypoxia. Immune checkpoint blockade (ICB) is a negative regulatory pathway of immunity. Immune checkpoint blockade (ICB) is an important immunotherapy method. However, inadequate immunogenicity reduces the overall response rate of ICB. In this study, a tumor microenvironment-responsive nanomedicine (Cu-FACD@MnO2@FA) was prepared to increase host immune response and increase intracellular oxygen levels. Cu-FACD@MnO2@FA preferentially enriched at the tumor site, combined with the immune checkpoint inhibitor alpha PD-L1, induced sufficient immunogenicity to treat colon cancer. Immunofluorescence detection of tumor cells and tissues showed that the expression of hypoxa-inducing factor 1α was significantly down-regulated after treatment and the expression of immunoactivity-related proteins was significantly changed. In vivo treatment in a bilateral tumor mouse model showed complete ablation of the primary tumor and efficient inhibition of the distal tumor. In this study, for the first time, the oxygenation effects of MnO2-coated Cu-doped carbon dots and chemodynamic therapy and a strategy of combining with immuno-blocking therapy were used for treating colon cancer.

BackgroundAstatine-211 is an α-emitter with high-energy α-ray and high cytotoxicity for cancer cells. However, the targeted alpha therapy (TAT) also suffers from insufficient systematic immune activation, resulting in tumor metastasis and relapse. Combined immune checkpoint blockade (ICB) with chemodynamic therapy (CDT) could boost antitumor immunity, which may magnify the immune responses of TAT. This study aims to discourage tumor metastasis and relapse by tri-model TAT-CDT-ICB strategy.MethodsWe successfully designed Mn-based radioimmunotherapy promoters (211At-ATE-MnO2-BSA), which are consisting of 211At, MnO2 and bovine serum albumin (BSA). The efficacy of 211At-ATE-MnO2-BSA was studied as monotherapy or in combination with anti-PD-L1 in both metastatic and relapse models. The immune effects of radioimmunotherapy promoters on cytotoxic T lymphocytes and dendritic cells (DCs) were analyzed by flow cytometry. Enzyme-linked immunosorbent assay and immunofluorescence were used to explore the underlying mechanism.ResultsSuch radioimmunotherapy promoters could not only enhance the therapeutic outcomes of TAT and CDT, but also induce robust anti-cancer immune activity by activating dendritic cells. More intriguingly, 211At-ATE-MnO2-BSA could effectively suppress the growths of primary tumors and distant tumors when combined with immune checkpoint inhibitors.ConclusionsThe tri-model TAT-CDT-ICB strategy provides a long-term immunological memory, which can protect against tumor rechallenge after eliminating original tumors. Therefore, this work presents a novel approach for TAT-CDT-ICB tri-modal cancer therapy with repressed metastasis and relapse in clinics.

Smart nanocomposite assemblies for multimodal cancer theranostics

Immune checkpoint blockade (ICB) is a kind of promising anti-tumor immunotherapy that can block the negative immune regulatory pathways using a particular antibody. Weak immunogenicity in most patients is a key obstacle to ICB therapy. Photodynamic therapy (PDT) is a non-invasive treatment that can enhance the immunogenicity of the host and realize systemic anti-tumor immunotherapy; yet tumor microenvironment hypoxia and glutathione overexpression severely restrict the PDT effect. To overcome the above issues, we design a combination therapy based on PDT and ICB. We prepared red carbon dot (RCD)-doped Cu-metal-organic framework nanoparticles (Cu-MOF@RCD) as smart nano-reactors because their tumor microenvironment and near-infrared light responsive property can decompose tumor endogenous H2O2 through Fenton-like reactions. Cu-MOF@RCD also shows clear near-infrared photothermal therapy (PTT) effect and has an ability to deplete glutathione (DG), which together enhances decomposition of cellular H2O2 and amplifies reactive oxygen species (ROS) levels in cells, thus leading to enhanced PDT and chemodynamic therapy (CDT) effect. Moreover, programmed cell death-ligand 1 antibody (anti-PD-L1) is used together to enable combination therapy, as Cu-MOF@RCD can significantly enhance host immunogenicity. In summary, the combination of Cu-MOF@RCD with anti-PD-L1 antibody exerts a synergistic PDT/PTT/CDT/DG/ICB therapy and can be used to eradicate the primary tumors and inhibit the growth of untreated distant tumors and tumor metastasis.

Immune checkpoint blockade (ICB) therapy still suffers from insufficient immune response and adverse effect of ICB antibodies. Chemodynamic therapy (CDT) has been demonstrated to be an effective way to synergize with ICB therapy. However, a low generation rate of reactive oxygen species and poor tumor penetration of CDT platforms still decline the immune effects. Herein, a charge-reversal nanohybrid Met@BF containing both Fe3O4 and BaTiO3 nanoparticles in the core and Metformin (Met) on the surface was fabricated for tumor microenvironment (TME)- and ultrasound (US)-activated piezocatalysis-chemodynamic immunotherapy of cancer. Interestingly, Met@BF had a negative charge in blood circulation, which was rapidly changed into positive when exposed to acidic TME attributed to quaternization of tertiary amine in Met, facilitating deep tumor penetration. Subsequently, with US irradiation, Met@BF produced H2O2 based on piezocatalysis of BaTiO3, which greatly enhanced the Fenton reaction of Fe3O4, thus boosting robust antitumor immune response. Furthermore, PD-L1 expression was inhibited by the local released Met to further augment the antitumor immune effect, achieving effective inhibitions for both primary and metastatic tumors. Such a combination of piezocatalysis-enhanced chemodynamic therapy and Met-mediated deep tumor penetration and downregulation of PD-L1 provides a promising strategy to augment cancer immunotherapy.

We prepared a tumor microenvironment-responsive magnetic nanofluid (MNF) for improving tumor targeting, imaging and treatment simultaneously. For this purpose, we synthesized sulfonamide-based amphiphilic copolymers with a suitable pKa at 7.0; then, we utilized them to prepare the tumor microenvironment-responsive MNF by self-assembly of the sulfonamide-based amphiphilic copolymers and hydrophobic monodispersed Fe3O4 nanoparticles at approximately 8 nm. After a series of characterizations, the MNF showed excellent application potential due to the fact of its high stability under physiological conditions and its hypersensitivity toward tumor stroma by forming aggregations within neutral or weak acidic environments. Due to the fact of its tumor microenvironment-responsiveness, the MNF showed great potential for accumulation in tumors, which could enhance MNF-mediated magnetic resonance imaging (MRI), magnetic hyperthermia (MH) and Fenton reaction (FR) in tumor. Moreover, in vitro cell experiment did not only show high biocompatibility of tumor microenvironment-responsive MNF in physiological environment, but also exhibit high efficacy on inhibiting cell proliferation by MH-dependent chemodynamic therapy (CDT), because CDT was triggered and promoted efficiently by MH with increasing strength of alternating magnetic field. Although the current research is limited to in vitro study, these positive results still suggest the great potential of the MNF on effective targeting, diagnosis, and therapy of tumor.