Recent Progress in Anti-Tumor Nanodrugs Based on Tumor Microenvironment Redox Regulation

Calcium peroxide functionalized mesoporous polydopamine nanoparticles triggered calcium overload for synergistic tumor gas/photothermal therapy

Cancer remains a significant global health challenge due to its high mortality rates and the limitations of conventional therapies, which are often associated with severe side effects and limited efficacy. Calcium (Ca2+) overload therapy has emerged as a promising strategy for inducing tumor cell apoptosis. However, existing methods that rely on direct Ca2+ delivery often face limited efficacy due to tumor adaptation mechanisms. In this study, we developed a multifunctional nanoparticle system (MLCH NPs) that synergistically combines Ca2+ overload, gas therapy (GT), and photothermal therapy (PTT). This nanoparticle system was based on mesoporous polydopamine (MPDA) nanoparticles loaded with l-arginine (LA) and calcium peroxide (CaO2), with hyaluronic acid (HA) modification to ensure tumor targeting and protect CaO2 from premature degradation. In the tumor microenvironment (TME), MLCH NPs released Ca2+, hydrogen peroxide (H2O2), and nitric oxide (NO), creating a self-sustaining Ca2+-H2O2-NO cycle that induced oxidative stress, mitochondrial damage, and sustained Ca2+ overload, leading to tumor cell apoptosis. The nanoparticles also harnessed the photothermal effect under 808 nm near-infrared irradiation to amplify NO and Ca2+ release, enhancing oxidative stress and sensitizing tumor cells. Both in vitro and in vivo studies confirmed that MLCH NPs significantly suppressed tumor progression through the synergistic effects of Ca2+ overload, GT, and PTT. This study proposes a novel platform for Ca2+/NO co-delivery and offers a promising approach for enhancing tumor therapies based on Ca2+ overload.

Synchronously Evoking Disulfidptosis and Ferroptosis via Systematical Glucose Deprivation Targeting SLC7A11/GSH/GPX4 Antioxidant Axis

Disulfidptosis and ferroptosis are recently identified programmed cell deaths for tumor therapy, both of which highly depend on the intracellular cystine/cysteine transformation on the cystine transporter solute carrier family 7 member 11/glutathione/glutathione peroxidase 4 (SLC7A11/GSH/GPX4) antioxidant axis. However, disulfidptosis and ferroptosis are usually asynchronous due to the opposite effect of cystine transport on them. Herein, systematic glucose deprivation, by both inhibiting upstream glucose uptake and promoting downstream glucose consumption, is proposed to synchronously evoke disulfidptosis and ferroptosis. As an example, Au nanodots and Fe-apigenin (Ap) complexes coloaded FeOOH nanoshuttles (FeOOH@Fe-Ap@Au NSs) are employed to regulate the SLC7A11/GSH/GPX4 axis for performing disulfidptosis- and ferroptosis-mediated tumor therapy synchronously. In this scenario, Au nanodots exhibit glucose oxidase-like activity when consuming massive glucose. Meanwhile, Ap can inhibit glucose uptake by downregulating glucose transporter 1, depriving glucose fundamentally. The systematical glucose deprivation limits the supplement of NADPH and suppresses cystine/cysteine transformation on the SLC7A11/GSH/GPX4 axis, thus solving the contradiction of cystine transport on disulfidptosis and ferroptosis. In addition, the efficient delivery of exogenous iron ions by FeOOH@Fe-Ap@Au NSs and self-supplied H2O2 through Au nanodots-catalytic glucose oxidation facilitate intracellular Fenton reaction and therewith help to amplify ferroptosis. As a result of synchronous occurrence of disulfidptosis and ferroptosis, FeOOH@Fe-Ap@Au NSs exhibit good efficacy in an ovarian cancer therapeutic model.

Photodynamic and Photothermal Co-Induced Efficient Anti-Tumor Immunotherapy

Currently, immunotherapy based on photothermal and the application of photodynamic therapy in anti-tumor treatment is showing great potential. Its uniqueness lies in the critical role of small molecule immunomodulators in promoting effective immune responses against tumors, and the use of laser-activated biophysical mechanisms to precisely trigger the swift demise of cancer cells, avoiding damage to surrounding normal tissues. However, the use of photodynamic therapy (PDT) alone is hampered by the tumors' hypoxic environment, resulting in poor antitumor effects, while photothermal therapy (PTT) alone cannot arouse enough antigen presentation. It is of great significance to design photosensitizers (PSs) that possess both PDT and PTT effects. Herein, a series of PSs with both PDT and PTT efficacy are reported, ultimately selecting Cy7-Naph as the star molecule due to its best overall phototherapeutic effect. Upon reactive oxygen species (ROS) production and thermogenesis in tumor cells, Cy7-Naph induced significant apoptosis and eventually boosted the release of damage-associated molecular patterns (DAMPs) under near-infrared (NIR) light irradiation. By combining Cy7-Naph with the Toll-like receptor agonist Resiquimod (R848), a synergistic treatment for bilateral tumor-bearing mice is achieved. This combination promotes dendritic cell (DC) maturation and increases the infiltration of cytotoxic T lymphocytes (CTLs), leading to significant inhibition of both primary and distant tumors.

Arsenene-Vanadene nanodots co-activate Apoptosis/Ferroptosis for enhanced chemo-immunotherapy

Triple-Negative Breast Cancer (TNBC) represents a highly aggressive subtype of breast cancer with an unfavorable prognosis, characterized by minimal immune infiltration and pronounced immune suppression, resulting in a limited response to immunotherapy. In this study, a multifunctional Arsenene-Vanadene nanodot (AsV) drug delivery system is introduced, which responds to the tumor microenvironment by releasing arsenic and vanadium. Arsenic undergoes oxidation to generate highly toxic trivalent arsenic, which induces apoptosis in tumor cells while utilizing apoptotic cell debris to transiently activate the immune system. Additionally, arsenic binds to cysteine, indirectly facilitating ferroptosis. Concurrently, vanadium's redox cycling properties are harnessed to trigger a Fenton-like reaction, promoting lipid peroxidation. Furthermore, ferroptosis is enhanced through the depletion of glutathione and inactivation of glutathione peroxidase 4 (GPX4), leading to the release of damage-associated molecular patterns and thereby amplifying the anti-tumor immune response. This study represents the first instance of integrating arsenene's apoptosis-inducing properties with vanadium's ferroptosis-enhancing effects, providing a synergistic approach to improving the immunotherapeutic response and offering a potential strategy for enhancing TNBC prognosis. STATEMENT OF SIGNIFICANCE: Triple-negative breast cancer (TNBC) exhibits resistance to immunotherapy due to its highly immunosuppressive tumor microenvironment. In this study, tumour-responsive Arsenene-Vanadene nanodots (AsV) were developed to induce a synergistic effect by triggering apoptosis and ferroptosis through microenvironment-specific mechanisms. The arsenic component generates cytotoxic trivalent arsenic, promoting apoptosis while binding to cysteine, thereby reducing GSH synthesis. Simultaneously, vanadium initiates lipid peroxidation through Fenton-like reactions and disruption of the glutathione/GPX4 axis, further amplifying ferroptotic cell death. This dual-action system transforms tumor cell debris into immune-stimulating signals while circumventing conventional immunotherapy limitations. As the first strategy integrating arsenic-induced apoptosis with vanadium-enhanced ferroptosis, this approach provides a mechanistic framework to overcome TNBC immunosuppression through coordinated cell death pathways, demonstrating potential for precision nanomedicine applications.

"Off-on-off"-based metal-organic framework fluorescent sensor for adenosine triphosphate detection and tumor microenvironment-triggered drug release

Extracellular adenosine triphosphate (ATP) and low extracellular pH are emerging targets for cancer treatment because they are crucial messengers shaping the tumor microenvironment (TME) and regulating tumor progression. Doxorubicin (Dox) is a common chemotherapeutic agent used against numerous solid tumors; however, its use is limited by its adverse effects, such as cardiotoxicity in healthy cells/tissues and multidrug resistance. Thus, using targeted nanocarriers can reduce the side effects of Dox. Herein, we report the construction of an ATP-responsive high fluorescent nanocomposite (ANZIF) that uses gold nanocluster self-assembly embedded in a zeolitic imidazolate framework-8. Based on "off-on-off" fluorescence changes, the ANZIF can be used for sensitive and selective ATP detection, with a detection limit of 4.3 μM. The ANZIF nanoplatform was fabricated using a self-assembly strategy for Dox loading (Dox-ANZIF). This unique nanoplatform exhibited ATP- and low-pH dual-triggered Dox release. In a cytotoxicity study, Dox-ANZIF, triggered by intracellular ATP and low pH, exhibited a selective release of Dox and showed a strong role in cancer cells. Compared with pure Dox, in vivo anticancer efficacy in tumor-bearing mice indicated that Dox-ANZIF significantly improved the antitumor effect and biological safety. This study provides a strategy for constructing a TME-triggered chemotherapy delivery system.

Enhanced Delivery of Photothermal Gelatin Nanoparticle for Redox Balanced Nanocatalytic Tumor Chemotherapy

Nanocatalytic platforms are promising in cancer therapeutics via combining multiple treatments, which can be leveraged through the metabolic dysfunction in cancer progression. However, the lack of effective tumor delivery platforms hampers this approach. Here, a gelatin-based platform is designed that is preloaded with gold nanoparticles and photothermal polypyrrole (GNPs@AuNPs-PPy) with an acid-induced doping enhancement. Benefiting from the tumor associated overexpression of H2O2, peroxidase-like Au nanoparticles induce a burst of oxidative reactive oxygen species in the local tumor microenvironment (TME). Subsequent orchestration of redox surroundings recruits immune cells, showcasing an effective antineoplastic pathway. Under near infrared light (NIR) irradiation, nanohybrids exhibit dual pH/NIR enhanced drug release within the TME, while allowing for multimodal imaging-guided theranostics. Leveraging this modality, GNPs@AuNPs-PPy delivers quercetin (a natural antitumor mediator) in TME, boosting anti-tumor therapy. The gelatin-mediated nanomedicine provides an alternative platform for combinatorial dynamic antitumor treatment.

A tunable stimuli-responsive module based on an α-hydroxymethyl-α,β-unsaturated carbonyl scaffold

The α-hydroxymethyl-α,β-unsaturated carbonyl (HMUC) scaffold represents a valuable framework for constructing nucleophile-responsive materials. However, nucleophiles are largely limited to thiols and amines. Given the ubiquity of thiols and amines in biological systems, this limitation hinders the creation of materials that can be selectively activated by exogenous stimuli. By tuning the electron density of the double bond and assessing its reactivity with various nucleophiles, we present here the discovery of the N-ethyl-2-(hydroxymethyl)acrylamide (NEHMAA) scaffold as a versatile building block for fabricating exogenous stimuli-responsive materials. The selenol species 4-cyanobenzylselenol (from its precursor bis(4-cyanobenzyl)diselenide, Se4) effectively activates NEHMAA-decorated "caged" molecules. Furthermore, the NEHMAA unit was employed to prepare prodrugs, and Se4-dependent cytotoxicity of these prodrugs was observed in cancer cells. The orthogonal reactivity between the NEHMAA unit and Se4 enriches the existing repertoire for constructing exogenous stimuli-responsive smart materials.

pH-responsive photothermal effect and heterojunction formation for tumor-specific pyroelectrodynamic and nanozyme-catalyzed starvation therapy

Pyroelectrodynamic therapy (PEDT) integrates photothermal ablation and catalytic generation of reactive oxygen species (ROS), yet tumor-specific PEDT remains unexplored. Herein, pyroelectric tetragonal BaTiO3 (tBT) nanoparticles (NPs) were capped with polyaniline (PANI) via a Pickering emulsion-masking method, followed by in situ deposition of MnO2 nanodots on PANI caps to synthesize Janus tBT@PANI-MnO2 NPs. PANI emeraldine salts (PANI-ES) at pH 6.5 display strong near-infrared II (NIR-II) absorption and 4.67-fold higher photothermal conversion efficiency than that of PANI emeraldine base at pH 7.4. MnO2 nanodots exhibit self-propagating glucose oxidase (GOx), peroxidase (POD), and catalase (CAT) catalytic activities, remodeling the tumor microenvironment and enhancing PTT and PEDT efficacy. Heterojunction formation with PANI-ES generates 1.63-fold higher pyroelectric potentials compared to pristine tBT NPs. The pyroelectric field selectively alters tumor cell membrane potential and, along with the self-propelled motion by asymmetrical thermophoresis from the Janus structure, promotes cellular uptake of NPs. Tumor accumulation of NPs increases 3.2 folds with broad intratumoral distributions of NPs and ROS. Synergistic toxicities to tumor cells arise from PANI-mediated photothermal effect, ROS generation from tBT-PANI heterojunctions, and MnO2 nanozymes-catalyzed glucose depletion. Integration of PEDT, mild PTT and MnO2-catalyzed starvation therapy completely inhibits tumor growth, extends animal survival, elevated intratumoral O2 levels, and suppressed adenosine triphosphate productions. Thus, this Janus NP design represents the first attempt to develop pH-responsive heterojunctions and enables tumor-specific PTT, PEDT and nanozyme-catalyzed starvation therapy. STATEMENT OF SIGNIFICANCE: Although phototherapy achieves light localization for tumor suppression, inevitable toxicities usually occur when light penetrates healthy tissues with accumulation of photoactive agents. Extensive efforts have been dedicated to exploring tumor microenvironment-responsive drug delivery systems, aiming to enhance tumor-targeting efficiency and treatment selectivity of anticancer agents. However, to date, no efforts have been made to develop a method that can achieve tumor-specific temperature elevation and pyroelectrodynamic therapy while simultaneously minimizing exposure to normal tissues. To address these challenges, a concise strategy is proposed to generate pyroelectric heterojunctions in response to the slightly acidic tumor microenvironment, taking advantages of reversible protonation and deprotonation properties of polyaniline. The tumor-specific conversion into polyaniline emeraldine salts triggers strong NIR-II absorptions and pyroelectric effect, and the self-propagated catalytic reactions of MnO2 nanozymes reinforce photothermal, pyroelectrodynamic and starvation therapies of tumors.

Borrow Strength to Exert: Low-Crystallinity Prussian Blue for Reduction Overload Enhanced Photothermal Therapy

The strategy "Borrow strength to exert" in Sun Tzu's Art of War refers to borrowing external forces to withstand the enemy. Inspired by this, applying this thought to cancer treatment can achieve a more efficient therapeutic effect. Therefore, a fulcrum to borrow the force is vital and significant. Compared with normal cells, tumor cells are more sensitive to redox stress owing to their abnormal redox metabolism. Herein, a regulatory protocol based on chloroauric acid (HAuCl4) is proposed to prepare small-size and low-crystallinity Prussian blue nanoparticles (LcPB NPs). Notably, LcPB NPs possess higher superoxide dismutase (SOD)-like enzyme activity to induce reduction overload and destroy metabolic processes and organelle functions, which leverages the redox status defect in tumors as the fulcrum. Due to the down-regulation of heat shock proteins (HSPs) mediated by redox imbalance, the inherent photothermal therapy (PTT) mode of LcPB NPs effectively inhibits tumor growth and disrupts calcium homeostasis. Additionally, LcPB NPs can improve the anticancer effect by inhibiting symbiotic bacteria. Meanwhile, their magnetic and optical response performance empowers magnetic resonance imaging (MRI) and photoacoustic imaging (PAI) for tumor diagnosis. Therefore, this work executing the strategy "Borrowing strength to exert" by disturbing the redox balance represents a new antineoplastic paradigm.

Multifunctional Artificial Peroxisome Basing on Lactate Oxidase as a Self-Cascade Enhancing Active Oxygen Amplifier for Tumor Therapy

The intricacy, diversity, and heterogeneity of cancers make research focus on developing multimodal synergistic therapy strategies. Herein, an oxygen (O2) self-feeding peroxisomal lactate oxidase (LOX)-based LOX-Ce6-Mn (LCM) was synthesized using a biomineralization approach, which was used for cascade chemodynamic therapy (CDT)/photodynamic therapy (PDT) combination therapies through dual depletion of lactate (Lac) and reactive oxygen species (ROS) generation. After endocytosis into tumor cells, the endogenous hydrogen peroxide (H2O2) can be converted to O2 by the catalase-like (CAT) activity of LCM, which can facilitate the catalytic reaction of LOX to consume more Lac and alleviate tumor hypoxia to enhance the generation of singlet oxygen (1O2) upon light irradiation. In addition, the H2O2 produced by LOX catalysis and oxidase-like (OXD) activity of LCM can be catalyzed into highly toxic hydroxyl radicals (•OH) via the Fenton-like reaction, enhancing oxidative damage to tumor cells. Both in vitro and in vivo experiments confirmed that LCM significantly promoted ROS accumulation and effectively inhibited tumor growth by inducing tumor cell autophagy under the combined effect of Lac depletion and CDT with PDT. Therefore, integrally designed LCM for reprogramming metabolism and the tumor microenvironment offers a promising multimodal strategy for tumor treatments.

Biodegradable Vanadium-Based Nanomaterials for Photothermal-Enhanced Tumor Ferroptosis and Pyroptosis

The designability and high reactivity of nanotechnology provide strategies for antitumor therapy by regulating the redox state in tumor cells. Here, we synthesize a kind of vanadium dioxide nanoparticle encapsulated in bovine serum albumin and containing disulfide bonds (VSB NPs) for photothermal-enhanced ferroptosis and pyroptosis effects. Mechanism studies show that disulfide bonds can effectively consume overexpressed glutathione (GSH) in the tumor microenvironment, leading to a decrease in glutathione peroxidase 4 (GPX4) activity. Simultaneously, tetravalent vanadium can induce a catalytic reaction of overexpressed H2O2, producing plenty of toxic hydroxyl radicals (·OH) and singlet oxygen (1O2), leading to tumor cell ferroptosis. In addition, the consumption of disulfide bonds can also lead to the degradation of nanoparticles into high-valent vanadates, activating thermal protein domain-associated protein 3 (NLRP3) inflammasomes and causing tumor cell pyroptosis. It is worth mentioning that VSB NPs can not only ablate tumor cells under near-infrared light irradiation but also further disrupt the redox homeostasis of the tumor microenvironment, thereby enhancing the ferroptosis and pyroptosis of tumor cells induced by biodegradable vanadium-based nanomaterials. This strategy, based on the biological effects of vanadium to regulate the redox state in tumor cells, provides possibilities for cancer treatment.

Selenium-Doped Nanoheterojunctions for Highly Efficient Cancer Radiosensitization

Exploring efficient and low-toxicity radiosensitizers to break through the bottleneck of radiation tolerance, immunosuppression and poor prognosis remains one of the critical developmental challenges in radiotherapy. Nanoheterojunctions, due to their unique physicochemical properties, have demonstrated excellent radiosensitization effects in radiation energy deposition and in lifting tumor radiotherapy inhibition. Herein, they doped selenium (Se) into prussian blue (PB) to construct a nano-heterojunction (Se@PB), which could promote the increase of Fe2+/Fe3+ ratio and conversion of Se to a high valence state with Se introduction. The Fe2+-Se-Fe3+ electron transfer chain accelerates the rate of electron transfer on the surface of the nanoparticles, which in turn endows it with efficient X-ray energy transfer and electron transport capability, and enhances radiotherapy physical sensitivity. Furthermore, Se@PB induces glutathione (GSH) depletion and Fe2+ accumulation through pro-Fenton reaction, thereby disturbs the redox balance in tumor cells and enhances biochemical sensitivity of radiotherapy. As an excellent radiosensitizer, Se@PB effectively enhances X-ray induced mitochondrial dysfunction and DNA damage, thereby promotes cell apoptosis and synergistic cervical cancer radiotherapy. This study elucidates the radiosensitization mechanism of Se-doped nanoheterojunction from the perspective of the electron transfer chain and biochemistry reaction, which provides an efficient and low-toxic strategy in radiotherapy.

A mesoporous theranostic platform for ultrasound and photoacoustic dual imaging-guided photothermal and enhanced starvation therapy for cancer

Tumor starvation therapy utilizing glucose oxidase (GOx), has gained traction due to its non-invasive and bio-safe attributes. However, its effectiveness is often hampered by severe hypoxia in the tumor microenvironment (TME), limiting GOx's catalytic activity. To address this issue, a multifunctional nanosystem based on mesoporous polydopamine nanoparticles (MPDA NPs) was developled to alleviate TME hypoxia. This nanosystem integrated GOx modification and oxygenated perfluoropentane (PFP) encapsulation to address hypoxia-related challenges in the TME. Under NIR laser irradiation, the MPDA NPs exhibit significant photothermal conversion efficacy, activating targeted tumor photothermal therapy (PTT), while also serving as proficient photoacoustic (PA) imaging agents. The ensuing temperature rise facilitates oxygen (O2) release and induces liquid-gas conversion of PFP, generating microbubbles for enhanced ultrasound (US) imaging signals. The supplied oxygen alleviates local hypoxia, thereby enhancing GOx-mediated endogenous glucose consumption for tumor starvation. Overall, the integration of ultrasound/photoacoustic dual imaging-guided PTT and starvation therapy within MPDA-GOx@PFP@O2 nanoparticles (MGPO NPs) presents a promising platform for enhancing the efficacay of tumor treatment by overcoming the complexities of the TME. STATEMENT OF SIGNIFICANCE: A multifunctional MPDA-based theranostic nanoagent was developed for US/PAI imaging-guided PTT and starvation therapy against tumor hypoxia by direct O2 delivery. The incorporation of oxygenated perfluoropentane (PFP) within the mesoporous structure of MGPO not only enables efficient US imaging but also helps in alleviating tumor hypoxia. Moreover, the strong near-infrared (NIR) absorption of MGPO NPs promote the generation of PFP microbubbles and release of oxygen, thereby enhancing US imaging and GOx-mediated starvation therapy. Such a multifunctional nanosystem leverages synergistic effects to enhance therapeutic efficacy while incorporating US/PA imaging for precise visualization of the tumor.

Magnetostrictive-piezocatalytic CoFe2O4@UiO-66 nanohybrid and its potential for deep-seated tumor treatment

Magnetostrictive CoFe2O4 (CFO) nanoparticles were encapsulated within a UiO-66 metal-organic-framework layer to form a CFO@UiO-66 nanohybrid. The deforming of CFO, in response to a high-frequency AC magnetic field, initiates the piezocatalytic property of UiO-66 to generate ˙OH radicals, which can kill cancer cells buried in thick tissues, showcasing bright potential for deep-seated tumor treatment.