An Acidity‐Unlocked Magnetic Nanoplatform Enables Self‐Boosting ROS Generation through Upregulation of Lactate for Imaging‐Guided Highly Specific Chemodynamic Therapy

A strategy of "adding fuel to the flames" enables a self-accelerating cycle of ferroptosis-cuproptosis for potent antitumor therapy

Cuproptosis in antitumor therapy faces challenges from copper homeostasis efflux mechanisms and high glutathione (GSH) levels in tumor cells, hindering copper accumulation and treatment efficacy. Herein, we propose a strategy of "adding fuel to the flames" for potent antitumor therapy through a self-accelerating cycle of ferroptosis-cuproptosis. Disulfiram (DSF) loaded hollow mesoporous copper-iron sulfide (HMCIS) nanoparticle with conjugation of polyethylene glycol (PEG) and folic acid (FA) (i.e., DSF@HMCIS-PEG-FA) was developed to swiftly release DSF, H2S, Cu2+, and Fe2+ in the acidic tumor microenvironment (TME). The hydrogen peroxide (H2O2) levels and acidity within tumor cells enhanced by the released H2S induce acceleration of Fenton (Fe2+) and Fenton-like (Cu2+) reactions, enabling the powerful tumor ferroptosis efficacy. The released DSF acts as a role of "fuel", intensifying catalytic effect ("flame") in tumor cells through the sustainable Fenton chemistry (i.e., "add fuel to the flames"). Robust ferroptosis in tumor cells is characterized by serious mitochondrial damage and GSH depletion, leading to excess intracellular copper that triggers cuproptosis. Cuproptosis disrupts mitochondria, compromises iron-sulfur (Fe-S) proteins, and elevates intracellular oxidative stress by releasing free Fe3+. These interconnected processes form a self-accelerating cycle of ferroptosis-cuproptosis with potent antitumor capabilities, as validated in both cancer cells and tumor-bearing mice.

Fenton-like nanoparticles capable of H2O2 self-supply and glutathione consumption for chemodynamic and chemotherapy of cancer

Chemodynamic therapy (CDT) utilizing the Fenton reaction to convert hydrogen peroxide (H2O2) into cytotoxic hydroxyl radicals (˙OH) has recently drawn extensive interest in tumor treatment. However, the therapeutic efficiency of CDT often suffers from high concentrations of glutathione (GSH), insufficient endogenous H2O2 and inefficient Fenton activity. Herein, a GSH-depleting and H2O2 self-providing nanosystem that can efficiently load copper ions and doxorubicin (DOX) (MSN-Cu2+-DOX) to induce enhanced CDT and chemotherapy is proposed. The results show that MSN-Cu2+-DOX could release Cu2+ and DOX under acidic conditions. Particularly, both the released Cu2+ and Cu2+ in MSN-Cu2+-DOX are available for ˙OH production via a Fenton-like reaction for CDT. Meanwhile, Cu2+ undergoes a reduction to Cu+ by depleting overexpressed GSH, thereby enhancing CDT. Moreover, the released DOX could not only be used for chemotherapy, but also promote the generation of endogenous H2O2 to improve the efficiency of a Cu-based Fenton-like reaction. Resultantly, this nanosystem featuring Fenton-like activity, GSH consumption, H2O2 self-sufficiency and chemotherapy exhibits a great antitumor effect with a tumor inhibition ratio of 93.05%. Overall, this study provides a promising strategy to enhance CDT for effective tumor therapy.

Comprehensively Optimizing Fenton Reaction Factors for Antitumor Chemodynamic Therapy by Charge-Reversal Theranostics

Chemodynamic therapy (CDT) is a highly tumor-specific treatment, while its efficacy is compromised by the intratumoral Fenton reaction efficiency, which is determined by the following reaction factors, including the availability of Fenton ions (e.g., Fe2+), the amount of H2O2, and the degree of acidity. Synchronous optimization of these factors is a big challenge for efficient CDT. Herein, a strategy of comprehensively optimizing Fenton reaction factors was developed for traceable multistage augmented CDT by charge-reversal theranostics. The customized pH-responsive poly(ethylene)glycol-poly(β-amino esters) (PEG-PAE) micelle (PM) was prepared as the carrier. Glucose oxidase (GOx), Fe2+, and pH-responsive second near-infrared (NIR-II) LET-1052 probe were coloaded by PM to obtain the final theranostics. The activity of metastable Fe2+ remained by the unsaturated coordination with PEG-PAE. Then tumor accumulation and exposure of Fe2+ were achieved by charge-reversal cationization of PEG-PAE, which was further enhanced by a GOx catalysis-triggered pH decrease. Together with the abundant H2O2 generation and pH decrease through GOx catalysis, the limiting factors of the Fenton reaction were comprehensively optimized, achieving the enhanced CDT both in vitro and in vivo. These findings provide a strategy for comprehensively optimizing intratumoral Fenton reaction factors to overcome the intrinsic drawbacks of current CDT.

Biomimetic Nanobomb for Synergistic Therapy with Inhibition of Cancer Stem Cells

Cancer stem cells (CSCs), a type of cell with self-renewal, unlimited proliferation, and insensitivity to common physical and chemical factors, are the key to cancer metastasis, recurrence, and chemo-resistance. Available CSCs inhibition strategies are mainly based on small molecule drugs, yet are limited by their off-target toxicity. The link between CSCs and non-CSCs interconversion is difficult to sever. In this work, a nanotherapeutic strategy based on MnO_x -loaded polydopamine (MnO_x /PDA) nanobombs with chemodynamic, photodynamic, photothermal and biodegradation properties to inhibit CSCs and non-CSCs concurrently is reported. The MnO_x /PDA nanobombs can directly disrupt the microenvironment and tumorigenic capacity of CSCs by generating hyperthermia, oxidative stress and alleviating hypoxia. The markers of CSCs are subsequently downregulated, leading to the clearance of CSCs. Meanwhile, the synergistic therapy mediated by MnO_x /PDA nanobombs can directly ablate the bulk tumor cells, thus cutting off the supply of CSCs transformation. For tumor targeting, MnO_x /PDA is coated with macrophage membrane. The final tumor inhibition rate of the synergistic therapy is 70.8% in colorectal cancer (CRC) model. Taken together, the present work may open up the exploration of nanomaterial-based synergistic therapy for the simultaneous elimination of therapeutically resistant CSCs and non-CSCs.

Harnessing inorganic nanomaterials for chemodynamic cancer therapy

The most important aspect of chemodynamic therapy (CDT) is the harnessing of Fenton or Fenton-like chemistry for cancer therapy within the tumor microenvironment, which occurs because of the moderate acidity and overexpressed H₂O₂ in the tumor microenvironment. Hydroxyl radicals (^•OH) produced within tumor cells via Fenton and Fenton-like reactions cause cancer cell death. Reactive oxygen species-mediated CDT demonstrates a desired anticancer impact without the need for external stimulation or the development of drug resistance. Cancer therapy based on CDT is known as a viable cancer therapy modality. This review discusses the most recent CDT advancements and provides some typical instances. As a result, potential methods for further improving CDT efficiency under the guidance of Fenton chemistry are offered.

Cancer cell membrane-coated C-TiO2 hollow nanoshells for combined sonodynamic and hypoxia-activated chemotherapy

Sonodynamic therapy (SDT) is a promising strategy for tumor treatment that satisfies all requirements of penetrating deep-seated tissues without causing additional trauma. However, the hypoxic tumor microenvironment impairs the therapeutic effect of SDT. The synergistic treatment of oxygen concentration-dependent SDT and bio-reductive therapy has been proven to be an effective approach to improve the therapeutic efficiency of SDT by exploiting tumor hypoxia. Herein, a biomimetic drug delivery system (C-TiO₂/TPZ@CM) was successfully synthesized for combined SDT and hypoxia-activated chemotherapy, which was composed of tirapazamine (TPZ)-loaded C-TiO₂ hollow nanoshells (HNSs) as the inner cores and cancer cell membrane (CM) as the outer shells. C-TiO₂ HNSs coated with CM achieved tumor targeting via homologous binding. C-TiO₂@CM as a nanocarrier loaded with TPZ in the presence of the trapping ability of CM and the special cavity structure of C-TiO₂ HNSs. Moreover, C-TiO₂ HNSs as sonosensitizers killed cancer cells under ultrasound (US) irradiation. Oxygen depletion during SDT induced a hypoxic environment in the tumor to activate the killing effect of co-delivered TPZ, thereby obtaining satisfactory synergistic therapeutic effects. In addition, C-TiO₂@CM exhibited remarkable biocompatibility without manifest damage and toxicity to the blood and major organs of the mice. The study highlighted that C-TiO₂/TPZ@CM served as a powerful biomimetic drug delivery system for effective SDT by exploiting tumor hypoxia. STATEMENT OF SIGNIFICANCE: • C-TiO₂@CM achieved tumor targeting via homologous binding. • C-TiO₂ hollow nanoshells could be used as a sonosensitizer and drug carrier for synergistic SDT and hypoxia-activated chemotherapy. • C-TiO₂/TPZ@CM showed no obvious toxicity under the injection dose.

Smart Nanozyme Platform with Activity-Correlated Ratiometric Molecular Imaging for Predicting Therapeutic Effects

Nanozymes with intrinsic enzyme-like characteristics have attracted enormous research interest in biological application. However, there is a lack of facile approach for evaluating the catalytic activity of nanozymes in living system. Herein, we develop a novel manganese-semiconducting polymer-based nanozyme (MSPN) with oxidase-like activity for reporting the catalytic activity of itself in acid-induced cancer therapy via ratiometric near-infrared fluorescence (NIRF)-photoacoustic (PA) molecular imaging. Notably, MSPN possess oxidase-like activity in tumor microenvironment, owing to the mixed-valent MnOx nanoparticles, which can effectively kill cancer cells. Because the semiconducting polymer (PFODBT) is conjugated with oxidase-responsive molecule (ORM), the catalytic activity of nanozyme can be correlated with the ratiometric signals of NIRF (FL₆₉₅ /FL₈₂₅ ) and PA (PA₆₈₀ /PA₇₈₀ ), which may provide new ideas for predicting anticancer efficacy of nanozymes in living system.

Oxygen-embedded quinoidal acene based semiconducting chromophore nanoprobe for amplified photoacoustic imaging

In this chapter, we summarize the advantages of photoacoustic imaging and the current methods of enhancing photoacoustic. We then provide detailed procedures for the synthesis and characterization of a photoacoustic imaging molecule, Nano(O-Nonacene)-PEG, developed in our research group. At the same time, we proved that the incorporation of Zn_0.4Fe_2.6O₄ can enhance the photoacoustic imaging effect of Nano(O-Nonacene)-PEG. This provides a new material for photoacoustic imaging to guide tumor treatment.

Cyanine-Dyad Molecular Probe for the Simultaneous Profiling of the Evolution of Multiple Radical Species During Bacterial Infections

Real-time monitoring of the evolution of bacterial infection-associated multiple radical species is critical to accurately profile the pathogenesis and host-defense mechanisms. Here, we present a unique dual wavelength near-infrared (NIR) cyanine-dyad molecular probe (HCy5-Cy7) for simultaneous monitoring of reactive oxygen and nitrogen species (RONS) variations both in vitro and in vivo. HCy5-Cy7 specifically turns on its fluorescence at 660 nm via superoxide or hydroxyl radical (O₂ ^.- , ^. OH)-mediated oxidation of reduced HCy5 moiety to Cy5, while peroxynitrite or hypochlorous species (ONOO^- , ClO^- )-induced Cy7 structural degradation causes the emission turn-off at 800 nm. Such multispectral but reverse signal responses allow multiplex manifestation of in situ oxidative and nitrosative stress events during the pathogenic and defensive processes in both bacteria-infected macrophage cells and living mice. Most importantly, this study may also provide new perspectives for understanding the bacterial pathogenesis and advancing the precision medicine against infectious diseases.