A pH-responsive ultrathin Cu-based nanoplatform for specific photothermal and chemodynamic synergistic therapy

Achievements and challenges in glucose oxidase-instructed multimodal synergistic antibacterial applications

Glucose oxidase (GOx) with unique catalytic properties and inherent biocompatibility can effectively oxidize both endogenous and exogenous glucose with oxygen (O2) into gluconic acid and hydrogen peroxide (H2O2). Accordingly, the GOx-based catalytic chemistry offers new possibilities for designing and constructing multimodal synergistic antibacterial systems. The consumption of glucose permanently downregulates bacterial cell metabolism by blocking essential energy supplies, inhibiting their growth and survival. Additionally, the production of gluconic acid could downregulates the pH within the bacterial infection microenvironment, enhancing the production of hydroxyl radicals (∙OH) from H2O2 via enhanced Fenton or Fendon-like reactions and triggering the pH-responsive release of drugs. Furthermore, the generated H2O2 in situ avoids the addition of exogenous hydrogen peroxide. Therefore, it is possible to design GOx-based multimodal antibacterial synergistic therapies by combining GOx-instructed cascade reactions with other therapeutic approaches such as chemodynamic therapies (CDT), hypoxia-activated prodrugs, photosensitizers, and stimuli-responsive drug release. Such multimodal strategies are expected to exhibit better therapeutic effects than single therapeutic modes. This tutorial review highlights recent advancements in GOx-instructed multimodal synergistic antibacterial systems, focusing on design philosophy and construction strategies. Current challenges and future prospects for advancing GOx-based multimodal antibacterial synergistic therapies are discussed.

Reducing the availability of endogenous copper and glucose for cascade starvation therapy and chemodynamic therapy

The rapid growth of tumors relies heavily on a continuous supply of essential nutrients, including glucose and copper. Disrupting the nutrient supply to tumors has become an increasingly focal point in tumor therapy. However, solely blocking the energy supply typically only hinders further tumor growth and may not effectively eliminate existing tumor cells. Herein, a multifunctional cascade nanoreactor (HPP/TPEN@GC) endowed with N, N, N', N'-tetrakis(2-pyridinylmethyl)-1,2-ethanediamine (TPEN, a copper chelator) and glucose oxidase (GOx) is designed to disrupt both glycolysis and mitochondrial metabolism, which further induce cascade chemodynamic therapy (CDT). HPP/TPEN@GC can react with endogenous copper and glucose, thereby reducing their availability. The absence of copper prevents proper assembly and function of mitochondrial complex IV (CIV), hindering mitochondrial metabolism; the lack of glucose cuts off glycolysis and leads to a tumor specific starvation. Meanwhile, the reactions catalyzed by HPP/TPEN@GC contribute to the generation of Fenton-like catalysts and hydrogen peroxide (H2O2), which can further react to produce highly toxic hydroxyl radical (·OH) for CDT. Taken together, the multifunctional cascade nanoreactor reduces the availability of endogenous copper and glucose, and further takes advantage of them to generate ·OH for cascade starvation-chemodynamic therapy. Collectively, this work represents a distinctive therapeutic paradigm to harness endogenous copper and glucose, which should inspire further studies to take full advantage of endogenous nutrients to combat various diseases, including tumors.

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

As a promising tumor treatment, chemodynamic therapy (CDT) can specifically catalyze H2O2 into the cytotoxic hydroxyl radical (·OH) via Fenton/Fenton-like reaction. However, the limited H2O2 and weakly acidic pH in tumor microenvironment (TME) would severely restrict the therapeutic efficiency of CDT. Here, a weakly acid activated, H2O2 self-supplied, hyaluronic acid (HA)-functionalized Ce/Cu bimetallic nanoreactor (CBPNs@HA) is elaborately designed for complementary chemodynamic-immunotherapy. In this nanoreactor, the component of peroxide group and Ce/Cu bimetals played the role of H2O2 self-supply and synergistic catalytic Fenton-like reaction, respectively. Specifically, CBPNs@HA can sensitively respond to TME (pH 6.8) and rapidly degrade to generate Ce4+, Cu+ and H2O2. The high-valence Ce4+ would be reduced by the intracellular glutathione (GSH) to generate Ce3+ and this process could be accelerated by Cu + via synergistic effect of Ce4+/Cu+. Particularly, the low-valence metallic ions (Ce3+ and Cu+) can react with the produced H2O2 to generate a multitude of reactive oxygen species (ROS). These cascaded effects can significantly amplify oxidative stress and seriously disturb the redox balance of tumor cells, inducing the potent immunogenic cell death (ICD) to release tumor-specific antigens and thereby activating the powerful antitumor immune responses. After combined with immune checkpoint blockade (ICB), CBPNs@HA can significantly heighten antitumor effects to inhibit the growth of primary and metastatic tumors, and dramatically prolong the survival lifetime of 4T1 tumor-bearing mice to 60 days. This work provides a materials-based strategy for enhanced CDT and highlights new opportunities for complementary chemodynamic-immunotherapy.

Cascade Catalytic Nanozymes Induce Tumor Ca2+ Overload and Ferroptosis by Reducing Energy Supply and Amplifying Oxidative Stress

Nanozyme-mediated nanocatalytic therapy, by mimicking the activity of redox enzymes, generates highly toxic reactive oxygen species (ROS) within tumor cells, thereby opening a pathway for tumor-specific therapy. However, achieving satisfactory therapeutic outcomes with nanozymes remains challenging due to the inherent complexity of the tumor microenvironment (TME). In this context, we designed a two-dimensional layered double hydroxide (LDH) nanozyme loaded with Au nanoparticles, while incorporating bioactive Ca2+ and Fe3+ ions (denoted as MgCaFe-LDH@Au NSs) to target the specific needs of the TME. The designed nanozyme mimics glucose oxidase to facilitate self-sufficient H2O2 production and simulates catalase and glutathione peroxidase to overcome the adverse conditions of hypoxia and elevated GSH levels in the TME. Subsequently, the nanozyme emulates peroxidase activity to generate ROS, amplifying oxidative stress and causing redox imbalance, ultimately inducing ferroptosis in tumor cells. Moreover, MgCaFe-LDH@Au NSs also function as an inorganic semiconductor sonosensitizer with a tunable band structure, enabling the generation of abundant ROS under ultrasound irradiation to achieve synergistic sonodynamic and catalytic therapy. Notably, the high levels of ROS induced by the nanozyme, along with the interference in tumor ATP synthesis, enhanced the calcium overload in the TME caused by the release of Ca2+ from the nanozyme. In summary, this two-dimensional nanomaterial, through nanozyme and ultrasound-catalyzed synergistic disruption of tumor energy supply and redox balance, exhibited significant therapeutic efficacy in a 4T1 tumor-bearing mouse model. This study also highlights the immense potential of multimetal LDHs as inducers of calcium overload and ferroptosis in tumor therapy.

Synthesis of Cu2O/CuZnAl-LDHs Heterojunction Photocatalyst with Enhanced Antibacterial Efficiency for Personal Protective Equipment

The growing prevalence of bacterial infections, along with the emergence of antibiotic-resistant bacteria, represents significant challenges to current anti-infective therapies. In order to address this critical issue, a series of Cu2O/CuZnAl-LDHs heterojunction photocatalysts were successfully synthesized via precise structural engineering. As a result, these photocatalysts demonstrated significantly enhanced antibacterial performance under simulated solar light irradiation, achieving over 99.9% inactivation of both Escherichia coli and Staphylococcus aureus within 30 minutes. Through comprehensive experimental characterization and theoretical simulations, we elucidated the synergistic mechanism: (1) the unique structure of CuZnAl-LDHs confers exceptional bacterial adsorption capacity; (2) the charge transfer pathway between Cu2O and CuZnAl-LDHs facilitates efficient segregation of photoinduced electron-hole pairs; (3) the subsequent production of reactive oxygen species (•OH and •O2-) leads to oxidative damage to bacterial membranes and intracellular components. In addition, the face mask constructed with the innovative Cu2O/CuZnAl-LDHs heterojunction photocatalyst upper layer demonstrated exceptional antibacterial activity bent over 500 cycles, with the loss ratio of Cu2O/CuZnAl-LDHs less than 1.5%. Notably, it exhibited a high particle filtration efficiency of 96.4%, while maintaining excellent air permeability at an airflow rate of 32 L min-1. This work establishes a platform to facilitate the design and synthesis of heterojunction photocatalysts, which have promising applications for the enhancement of personal protective equipment.

Emerging glucose oxidase-delivering nanomedicines for enhanced tumor therapy

Abnormalities in glucose metabolism have been shown to characterize malignant tumors. Glucose depletion by glucose oxidase (GOD) has shown great potential in tumor therapy by causing tumor starvation. Since 2017, nanomedicines have been designed and utilized to deliver GOD for more precise and effective glucose modulation, which can overcome intrinsic limitations of different cancer therapeutic modalities by remodeling the tumor microenvironment to enhance antitumor therapy. To date, the topic of GOD-delivering nanomedicines for enhancing tumor therapy has not been comprehensively summarized. Herein, this review aims to provide an overview and discuss in detail recent advances in GOD delivery and directly involved starvation therapy strategies, GOD-sensitized various tumor therapy strategies, and GOD-mediated multimodal antitumor strategies. Finally, the challenges and outlooks for the future progress of the emerging tumor therapeutic nanomedicines are discussed. This review provides intuitive and specific insights to a broad audience in the fields of nanomedicines, biomaterials, and cancer therapy.

Near-Infrared Multifunctional Antitumor Nanomaterial of Bismuth Sulfide Heterojunction Coupled with Mesoporous Polydopamine

Bismuth sulfide@bismuth nanorods (Bi2S3@Bi NRs) have emerged as promising photodynamic therapeutic agents due to Bi2S3@Bi being able to produce reactive oxygen species from self-supplied O2. Combining photothermal and photodynamic therapies with chemotherapy is attractive but difficult to achieve. Here, we develop a subtle method to wrap Bi2S3@Bi NRs with photothermal mesoporous polydopamine, where chemotherapy drug doxorubicin hydrochloride can be loaded, thus providing multifunctional antitumor nanospheres. To our delight, the prepared triple-functional material exhibits excellent antitumor efficacy toward tumor cells under near-infrared light irradiation. This multifunctional antitumor nanomaterial is not only biocompatible but also suitable for tumor hypoxic microenvironments, having much better efficacy than single- or double-functional materials. This study highlights the great potential of combining photothermal, photodynamic, and chemotherapies.

A multifunctional hyaluronic acid-engineered mesoporous nanoreactor with H2O2/O2 self-sufficiency for pH-triggered endo-lysosomal escape and synergetic cancer therapy

Monotherapy has poor accuracy and is easily restricted by tumor microenvironment (TME). Remodeling components of the TME to activate multimodal cancer therapy with high precision and efficiency is worth exploring. A multifunctional nanoreactor was fabricated by decorating chlorin e6-modified and PEGylated hyaluronic acid bearing diethylenetriamine-conjugated dihydrolipoic acid on the surface of glucose oxidase (GOx)-loaded hollow mesoporous CuS nanoparticles (labeled as GOx@HCuS@HA). This nanoreactor efficiently targets tumor sites, enhances cellular internalization, and swiftly escapes from endo-lysosomes after intravenous injection. Subsequently, GOx@HCuS@HA was activated in hyaluronidase and H + -rich TME to produce H2O2 and gluconic acid through the oxidation of glucose, which not only blocks the energy supply of cancer cells, executing starvation treatment (ST), but also bolsters hydroxyl radicals (•OH)-based chemodynamic therapy (CDT) by Fenton-like reaction between HCuS and H2O2. Furthermore, reductive Cu ions could catalyze H2O2 to produce O2 to alleviate the limitation of photodynamic therapy (PDT) for tumor hypoxia. Additionally, the photothermal effect of HCuS under NIR irradiation could increase the temperature of tumor tissues to perform photothermal therapy (PTT). This synergistic antitumor strategy could ultimately achieve precise tumor cell destruction and maintain excellent biosafety. Hence, this nanoreactor offer promising prospects for efficient tumor treatment.

Carbon-supported Fe single atom nanozymes with long-lasting ROS generation and high NIR photothermal performance for synergistic cancer therapy

Synergistic therapy combining photothermal therapy (PTT) and chemodynamic therapy (CDT) has proven to be a highly effective strategy for cancer treatment. However, PTT heavily relies on the accumulation of therapeutic agents at the tumor site. The peroxidase (POD) activity of common catalysts can be rapidly exhausted during the accumulation process, prior to laser intervention, thereby diminishing the synergistic enhancement effect of the combined therapy. Therefore, a carbon-based nanozyme featuring single Fe atoms (Fe SAzyme) for long-term reactive oxygen species (ROS) generation is developed to address this challenge. While maintaining robust POD performance, Fe SAzyme exhibits a high photothermal conversion efficiency of 64.78 % at 808 nm. Short-term hyperthermia resulted in rapid tumor ablation, while sustained ROS generation induced persistent oxidative stress on cancer cells. Both in vitro and in vivo biological tests confirmed significant tumor growth inhibition, demonstrating the potential of Fe SAzyme as a potent agent for cancer treatment.

Rational Design of Nanozymes for Engineered Cascade Catalytic Cancer Therapy

Nanozymes have shown significant potential in cancer catalytic therapy by strategically catalyzing tumor-associated substances and metabolites into toxic reactive oxygen species (ROS) in situ, thereby inducing oxidative stress and promoting cancer cell death. However, within the complex tumor microenvironment (TME), the rational design of nanozymes and factors like activity, reaction substrates, and the TME itself significantly influence the efficiency of ROS generation. To address these limitations, recent research has focused on exploring the factors that affect activity and developing nanozyme-based cascade catalytic systems, which can trigger two or more cascade catalytic processes within tumors, thereby producing more therapeutic substances and achieving efficient and stable cancer therapy with minimal side effects. This area has shown remarkable progress. This Perspective provides a comprehensive overview of nanozymes, covering their classification and fundamentals. The regulation of nanozyme activity and efficient strategies of rational design are discussed in detail. Furthermore, representative paradigms for the successful construction of cascade catalytic systems for cancer treatment are summarized with a focus on revealing the underlying catalytic mechanisms. Finally, we address the current challenges and future prospects for the development of nanozyme-based cascade catalytic systems in biomedical applications.

Fabrication of the multifunctional Pd modified NiCuFe Prussian blue analogue nanoplatform and its sensitive colorimetric detection of L-cysteine

It is essential to establish a simple, effective and sensitive platform for L-Cysteine (L-Cys) detection because the level of L-Cys is related to many diseases in the human body. Herein, we successfully fabricated polyaniline bridging NiCuFe Prussian blue analogue@palladium (NiCuFe@Pd) nanocomposite with integration of photothermal conversion performance and catalytic performance. And, various spectroscopic and microscopic techniques were adopted to prove the formation of the nanocomposite. 4-nitrothiophenol and 3,3',5,5'-tetramethylbenzidine (TMB) were employed to prove the catalytic activity of the nanocomposite. Due to the catalytic activity, the nanocomposite was used as a nanoplatform for colorimetric detection of L-Cys, which showed high sensitivity with a detection limit as low as 0.027 μM. In addition, the excellent photothermal conversion performance makes it a potential candidate for photothermal therapy for various diseases. This study may be beneficial to promote the construction of novel nanostructures and their medical application.

APE1-Activated and NIR-II Photothermal-Enhanced Chemodynamic Therapy Guided by Amplified Fluorescence Imaging

The development of intelligent nanotheranostic technology that integrates diagnostic and therapeutic functions holds great promise for personalized nanomedicine. However, most of the nanotheranostic agents exhibit "always-on" properties and do not involve an amplification step, which may largely limit imaging contrast and restrict therapeutic efficacy. Herein, we construct a novel nanotheranostic platform (Hemin/DHPs/PDA@CuS nanocomposite) by assembling DNA hairpin probes (DHPs) and hemin on the surface of PDA@CuS nanosheets that enables amplified fluorescence imaging and activatable chemodynamic therapy (CDT) of tumors. The cancer-relevant APE1 triggers nucleic acid amplification with DHPs to generate activatable and amplified fluorescence signals for discriminating cancer cells from normal cells. Meanwhile, excessive G-quadruplex/hemin-based DNAzyme are also activated, and they function as Fenton-like catalysts to catalyze the production of highly toxic hydroxyl radicals (•OH) for CDT. Moreover, owing to the excellent photothermal conversion efficiency in the near-infrared-II (NIR-II) window, the PDA@CuS not only improves the catalytic performance of CDT but also furnishes PTT. A remarkable antitumor therapeutic effect is demonstrated both in vitro and in vivo. Therefore, the Hemin/DHPs/PDA@CuS nanocomposite is expected to provide a promising avenue for precise imaging-guided antitumor therapy.

High Entropy 2D Layered Double Hydroxide Nanosheet Toward Cascaded Nanozyme-Initiated Chemodynamic and Immune Synergistic Therapy

High-entropy nanomaterials (HEMs) are a hot topic in the fields of energy and catalysis. However, in terms of promising biomedical applications, potential therapeutic studies involving HEMs are unprecedented. Herein, we demonstrated high entropy two-dimensional layered double hydroxide (HE-LDH) nanoplatforms with versatile physicochemical advantages that reprogram the tumor microenvironment (TME) and provide antitumor treatment via cascaded nanoenzyme-initiated chemodynamic and immune synergistic therapy. In response to the TME, the multifunctional HE-LDHs sequentially release metal ions, such as Co2+, Fe3+, and Cu2+, exhibiting exquisite superoxide dismutase (SOD), peroxidase (POD), and glutathione peroxidase (GPX) activities. The multiple enzymatic activities convert specific tumor metabolites into a continuous supply of cytotoxic reactive oxygen species (ROS) to relieve hypoxia under a TME. Thus, HE-LDHs facilitate robust nanozyme-initiated chemodynamic therapy (NCDT), achieving high therapeutic efficacy without obvious side effects. In addition, the release of Zn2+ from the HE-LDH matrix triggers the cyclic GMP-AMP synthase/stimulator of interferon gene (cGAS/STING) signaling pathway, boosting the innate immunotherapeutic efficacy. The intratumoral applications of the nanocomposite in tumor-bearing mice models indicate that HE-LDH-mediated NCDT and immune synergistic therapy effectively upregulated the expression of relevant antitumor cytokines and induced cytotoxic T lymphocyte infiltration, showing superior efficacy in inhibiting tumor growth. Therefore, this work opens a new research direction toward synchronized NCDT and immunotherapy of tumors using HEMs for advanced healthcare.

Bifunctional Bismuth-Based Layered Double Hydroxide Sonosensitizer for Magnetic Resonance Imaging-Guided Sonodynamic Cancer Therapy

Novel inorganic sonosensitizers with excellent reactive oxygen species (ROS) generation activity and multifunctionality are appealing in sonodynamic therapy (SDT). Herein, amorphous bismuth (Bi)-doped CoFe-layered double hydroxide (a-CoBiFe-LDH) nanosheets are proposed via crystalline-to-amorphous phase transformation strategy as a new type of bifunctional sonosensitizer, which allows ultrasound (US) to trigger ROS generation for magnetic resonance imaging (MRI)-guided SDT. Importantly, a-CoBiFe-LDH nanosheets exhibit much higher ROS generation activity (≈6.9 times) than that of traditional TiO2 sonosensitizer under US irradiation, which can be attributed to the acid etching-induced narrow band gap, high electron (e-)/hole (h+) separation efficiency and inhibited e-/h+ recombination. In addition, the paramagnetic properties of Fe ion endow a-CoBiFe-LDH with excellent MRI contrast ability, making it a promising contrast agent for T2-weighted MRI. After modification with polyethylene glycol, a-CoBiFe-LDH nanosheets can function as a high-efficiency sonosensitizer to activate p53, MAPK, oxidative phosphorylation, and apoptosis-related signaling pathways, ultimately inducing cell apoptosis in vitro and tumor ablation in vivo under US irradiation, which shows great potential for clinical cancer treatment.

Recent advances in copper homeostasis-involved tumor theranostics

As the third essential trace element in the human body, copper plays a crucial role in various physiological processes, which lays the foundation for its broad applications in cancer treatments. The overview of copper, including pharmacokinetics, signaling pathways, and homeostasis dysregulation, is hereby discussed. Additionally, cuproptosis, as a newly proposed cell death mechanism associated with copper accumulation, is analyzed and further developed for efficient cancer treatment. Different forms of Cu-based nanoparticles and their advantages, as well as limiting factors, are introduced. Moreover, the unique characteristics of Cu-based nanoparticles give rise to their applications in various imaging modalities. In addition, Cu-based nanomaterials are featured by their excellent photothermal property and ROS-associated tumor-killing potential, which are widely explored in diverse cancer therapies and combined therapies. Reducing the concentration of Cu2+/Cu+ is another cancer-killing method, and chelators can meet this need. More importantly, challenges and future prospects are identified for further research.

A Se Nanoparticle/MgFe-LDH Composite Nanosheet as a Multifunctional Platform for Osteosarcoma Eradication, Antibacterial and Bone Reconstruction

Despite advances in treating osteosarcoma, postoperative tumor recurrence, periprosthetic infection, and critical bone defects remain critical concerns. Herein, the growth of selenium nanoparticles (SeNPs) onto MgFe-LDH nanosheets (LDH) is reported to develop a multifunctional nanocomposite (LDH/Se) and further modification of the nanocomposite on a bioactive glass scaffold (BGS) to obtain a versatile platform (BGS@LDH/Se) for comprehensive postoperative osteosarcoma management. The uniform dispersion of negatively charged SeNPs on the LDH surface restrains toxicity-inducing aggregation and inactivation, thus enhancing superoxide dismutase (SOD) activation and superoxide anion radical (·O2 -)-H2O2 conversion. Meanwhile, Fe3+ within the LDH nanosheets can be reduced to Fe2+ by depleting glutathione (GSH) in the tumor microenvironments (TME), which can catalyze H2O2 into highly toxic reactive oxygen species. More importantly, incorporating SeNPs significantly promotes the anti-bacterial and osteogenic properties of BGS@LDH/Se. Thus, the developed BGS@LDH/Se platform can simultaneously inhibit tumor recurrence and periprosthetic infection as well as promote bone regeneration, thus holding great potential for postoperative "one-stop-shop" management of patients who need osteosarcoma resection and scaffold implantation.

S-Doped Hollow Multi-Metallic Prussian Blue Analogue (PBA) Nanoplatform for Enhanced Anticancer for Cervical Cancer

Purpose

Developing novel multimodal nanomaterials-based anticancer agents to meet complex clinical demands is an urgent challenge. This study presents a novel uniform hollow S-doped NiCuFe Prussian blue analogue (NiCuFe-S) with satisfactory size and properties as anticancer agents for efficient cervical cancer therapy using a simple and environmentally friendly procedure.

Methods

The formation mechanism and the reason for enhanced performance of NiCuFe-S were characterized and discussed by diverse spectroscopic and microscopic methods. Moreover, to demonstrate the anti-cancer ability of NiCuFe-S, in vitro and in vivo experiments were carried out.

Results

Compared to the non-doped NiCuFe, the NiCuFe-S exhibited significantly enhanced photothermal and catalytic activity attributed to the electronic bandgap-narrowing effect and the increased electron circuit paths resulting from S doping. The hollow structure of NiCuFe-S facilitated the loading of small-molecule drugs, such as doxorubicin (DOX), transforming it into a multimodal nanoplatform for cervical cancer treatment. In vitro and in vivo experiments proved the potential of the NiCuFe-S nanotheranostic agent for chemodynamic therapy (CDT), photothermal therapy (PTT), and chemotherapy for cervical cancer.

Conclusion

This research not only overcomes inherent limitations but also significantly broadens the applications of Prussian blue analogues in biomedicine.

A functionalized cell membrane biomimetic nanoformulation based on layered double hydroxide for combined tumor chemotherapy and sonodynamic therapy

The development of nanoformulations with simple compositions that can exert targeted combination therapy still remains a great challenge in the area of precision cancer nanomedicine. Herein, we report the design of a multifunctional nanoplatform based on methotrexate (MTX)-loaded layered double hydroxide (LDH) coated with chlorin e6 (Ce6)-modified MCF-7 cell membranes (CMM) for combined chemo/sonodynamic therapy of breast cancer. LDH nanoparticles were in situ loaded with MTX via coprecipitation, and coated with CMM that were finally functionalized with phospholipid-modified Ce6. The created nanoformulation of LDH-MTX@CMM-Ce6 displays good colloidal stability under physiological conditions and can release MTX in a pH-dependent manner. We show that the formulation can homologously target breast cancer cells, and induce their significant apoptosis through arresting the cell cycle via cooperative MTX-based chemotherapy and ultrasound (US)-activated sonodynamic therapy. The assistance of US can not only trigger sonosensitizer Ce6 to produce reactive oxygen species, but also enhance the cellular uptake of LDH-MTX@CMM-Ce6 via an acoustic cavitation effect. Upon intravenous injection and US irradiation, LDH-MTX@CMM-Ce6 displays an admirable antitumor performance towards a xenografted breast tumor mouse model. Furthermore, the modification of Ce6 on the CMM endows the LDH-based nanoplatform with fluorescence imaging capability. The developed LDH-based nanoformulation here provides a general intelligent cancer nanomedicine platform with simple composition and homologous targeting specificity for combined chemo/sonodynamic therapy and fluorescence imaging of tumors.

Ternary NiCoTi-layered double hydroxide nanosheets as a pH-responsive nanoagent for photodynamic/chemodynamic synergistic therapy

Combining photodynamic therapy (PDT) with chemodynamic therapy (CDT) has been proven to be a promising strategy to improve the treatment efficiency of cancer, because of the synergistic therapeutic effect arising between the two modalities. Herein, we report an inorganic nanoagent based on ternary NiCoTi-layered double hydroxide (NiCoTi-LDH) nanosheets to realize highly efficient photodynamic/chemodynamic synergistic therapy. The NiCoTi-LDH nanosheets exhibit oxygen vacancy-promoted electron-hole separation and photogenerated hole-induced O2-independent reactive oxygen species (ROS) generation under acidic circumstances, realizing in situ pH-responsive PDT. Moreover, due to the effective conversion between Co3+ and Co2+ caused by photogenerated electrons, the NiCoTi-LDH nanosheets catalyze the release of hydroxyl radicals (·OH) from H2O2 through Fenton reactions, resulting in CDT. Laser irradiation enhances the catalyzed ability of the NiCoTi-LDH nanosheets to promote the ROS generation, resulting in a better performance than TiO2 nanoparticles at pH 6.5. In vitro and in vivo experimental results show conclusively that NiCoTi-LDH nanosheets plus irradiation lead to efficient cell apoptosis and significant inhibition of tumor growth. This study reports a new pH-responsive inorganic nanoagent with oxygen vacancy-promoted photodynamic/chemodynamic synergistic performance, offering a potentially appealing clinical strategy for selective tumor elimination.

Biocompatible Copper-Based Nanocomposites for Combined Cancer Therapy

Copper (Cu) and Cu-based nanomaterials have received tremendous attention in recent years because of their unique physicochemical properties and good biocompatibility in the treatment of various diseases, especially cancer. To date, researchers have designed and fabricated a variety of integrated Cu-based nanocomplexes with distinctive nanostructures and applied them in cancer therapy, mainly including chemotherapy, radiotherapy (RT), photothermal therapy (PTT), chemodynamic therapy (CDT), photodynamic therapy (PDT), cuproptosis-mediated therapy, etc. Due to the limited effect of a single treatment method, the development of composite diagnostic nanosystems that integrate chemotherapy, PTT, CDT, PDT, and other treatments is of great significance and offers great potential for the development of the next generation of anticancer nanomedicines. In view of the rapid development of Cu-based nanocomplexes in the field of cancer therapy, this review focuses on the current state of research on Cu-based nanomaterials, followed by a discussion of Cu-based nanocomplexes for combined cancer therapy. Moreover, the current challenges and future prospects of Cu-based nanocomplexes in clinical translation are proposed to provide some insights into the design of integrated Cu-based nanotherapeutic platforms.

Boosting the sonodynamic performance of CoBiMn-layered double hydroxide nanoparticles via tumor microenvironment regulation for ultrasound imaging-guided sonodynamic therapy

Sonodynamic therapy (SDT), a promising strategy for cancer treatment with the ability for deep tissue penetration, has received widespread attention in recent years. Sonosensitizers with intrinsic characteristics for tumor-specific curative effects, tumor microenvironment (TME) regulation and tumor diagnosis are in high demand. Herein, amorphous CoBiMn-layered double hydroxide (a-CoBiMn-LDH) nanoparticles are presented as multifunctional sonosensitizers to trigger reactive oxygen species (ROS) generation for ultrasound (US) imaging-guided SDT. Hydrothermal-synthesized CoBiMn-LDH nanoparticles are etched via a simple acid treatment to obtain a-CoBiMn-LDH nanoparticles with abundant defects. The a-CoBiMn-LDH nanoparticles give greater ROS generation upon US irradiation, reaching levels ~ 3.3 times and ~ 8.2 times those of the crystalline CoBiMn-LDH nanoparticles and commercial TiO2 sonosensitizer, respectively. This excellent US-triggered ROS generation performance can be attributed to the defect-induced narrow band gap and promoted electrons and holes (e-/h+) separation. More importantly, the presence of Mn4+ enables the a-CoBiMn-LDH nanoparticles to regulate the TME by decomposing H2O2 into O2 for hypoxia relief and US imaging, and consuming glutathione (GSH) for protection against ROS clearance. Biological mechanism analysis shows that a-CoBiMn-LDH nanoparticles modified with polyethylene glycol can serve as a multifunctional sonosensitizer to effectively kill cancer cells in vitro and eliminate tumors in vivo under US irradiation by activating p53, apoptosis, and oxidative phosphorylation-related signaling pathways.

Facile preparation of high-efficiency peroxidase mimics: modulation of the catalytic microenvironment of LDH nanozymes through defect engineering induced by amino acid intercalation

Nanozymes have gained much attention as a replacement for natural enzymes duo to their unique advantages. Two-dimensional layered double hydroxide (LDH) nanomaterials with high physicochemical plasticity are emerging as the main forces for the construction of nanozymes. Unfortunately, high-performance LDH nanozymes are still scarce. Recently, defects in nanomaterials have been verified to play a significant role in modulating the catalytic microenvironment, thereby improving catalytic performances of nanozymes. Therefore, the marriage between defect engineering and LDH nanozymes is expected to spark new possibilities. In this work, twenty kinds of natural amino acids were separately inserted into the interlayer of CoFe-LDH to obtain defect-rich CoFe-LDH nanozymes. The peroxidase (POD)-like activity and catalytic mechanism of the as-prepared LDH nanozymes were systematically studied. The results showed that the intercalation of amino acids can effectively enhance the POD-like activity of LDH nanozymes owing to the increasing oxygen/metal vacancies. And l-cysteine intercalated LDH exhibited the highest catalytic activity ascribed to its thiol group. As a proof of concept, LDH nanozymes with superb POD-like activity were used in biosensing and antibacterial applications. This work suggests that modulating the catalytic microenvironment through defect engineering is an effective way to obtain high-efficiency POD mimics.

Advances of Layered Double Hydroxide-Based Materials for Tumor Imaging and Therapy

Layered double hydroxides (LDH) are a class of functional anionic clays that typically consist of orthorhombic arrays of metal hydroxides with anions sandwiched between the layers. Due to their unique properties, including high chemical stability, good biocompatibility, controlled drug loading, and enhanced drug bioavailability, LDHs have many potential applications in the medical field. Especially in the fields of bioimaging and tumor therapy. This paper reviews the research progress of LDHs and their nanocomposites in the field of tumor imaging and therapy. First, the structure and advantages of LDH are discussed. Then, several commonly used methods for the preparation of LDH are presented, including co-precipitation, hydrothermal and ion exchange methods. Subsequently, recent advances in layered hydroxides and their nanocomposites for cancer imaging and therapy are highlighted. Finally, based on current research, we summaries the prospects and challenges of layered hydroxides and nanocomposites for cancer diagnosis and therapy.

Tumor targeted nanohybrid for dual stimuli responsive and NIR amplified photothermal/photo-induced thermodynamic/chemodynamic combination therapy

The combination of photodynamic (PDT) and chemodynamic therapy (CDT) for cancer treatment has gathered a lot of attention in recent years. However, its efficacy is severely limited by elevated levels of hypoxia and glutathione (GSH) in the tumor microenvironment (TME). Multifunctional nanoparticles that can help remodel the TME while facilitating PDT/CDT combination therapy are the need of the hour. To this effect, we have developed O2self-supplying, free radical generating nanohybrids that exhibit near infra-red (NIR) triggered photothermal (PTT)/photo-induced thermodynamic (P-TDT) and CDT for efficient breast cancer treatment. The surface of nanohybrids has been further modified by biointerfacing with cancer cell membrane. The biomimetic nanohybrids have been comprehensively characterized and found to exhibit high 2,2'-azobis-[2-(2-imidazolin-2-yl)propane] dihydrochloride (AIPH) loading, GSH depletion, oxygen self-supply with TME responsive AIPH release. Biological activity assays demonstrate efficient cellular uptake with homotypic targeting, excellent hemo- and cytocompatibility as well as high intracellular reactive oxygen species generation with synergistic cytotoxicity against tumor cells. The multifunctional nanohybrid proposed in the present study provides an attractive strategy for achieving NIR responsive, tumor targeted PTT/P-TDT/CDT combination therapy for breast cancer treatment.

Two-dimensional nanomaterials induced nano-bio interfacial effects and biomedical applications in cancer treatment

Two-dimensional nanomaterials (2D NMs), characterized by a large number of atoms or molecules arranged in one dimension (typically thickness) while having tiny dimensions in the other two dimensions, have emerged as a pivotal class of materials with unique properties. Their flat and sheet-like structure imparts distinctive physical, chemical, and electronic attributes, which offers several advantages in biomedical applications, including enhanced surface area for efficient drug loading, surface-exposed atoms allowing precise chemical modifications, and the ability to form hierarchical multilayer structures for synergistic functionality. Exploring their nano-bio interfacial interactions with biological components holds significant importance in comprehensively and systematically guiding safe applications. However, the current lack of in-depth analysis and comprehensive understanding of interfacial effects on cancer treatment motivates our ongoing efforts in this field. This study provides a comprehensive survey of recent advances in utilizing 2D NMs for cancer treatment. It offers insights into the structural characteristics, synthesis methods, and surface modifications of diverse 2D NMs. The investigation further delves into the formation of nano-bio interfaces during their in vivo utilization. Notably, the study discusses a wide array of biomedical applications in cancer treatment. With their potential to revolutionize therapeutic strategies and outcomes, 2D NMs are poised at the forefront of cancer treatment, holding the promise of transformative advancements.

Tumor Targeted Cuprous-Based Nanocomposite as Responsive Cascade Nanocatalyst for Efficient Tumor Synergistic Therapy

The single-functionality of traditional chemodynamic therapy (CDT) reagents usually limits the therapeutic efficacy of cancer treatment. Synergistic nanocomposites that involve cascade reaction provide a promising strategy to achieve satisfactory anticancer effects. Herein, a cuprous-based nanocomposite (CCS@GOx@HA) is fabricated, which owns the tumor targeting ability and can undergo tumor microenvironment responsive cascade reaction to enhance the tumor therapeutic efficiency significantly. Surface modification of nanocomposite with hyaluronic acid enables the targeted delivery of the nanocomposite to cancer cells. Acid-triggered decomposition of nanocomposite in cancer cell results in the release of Cu+ , Se2- and GOx. The Cu+ improves the Fenton-like reaction with endogenous H2 O2 to generate highly toxic • OH for CDT. While GOx can not only catalyze the in situ generation of endogenous H2 O2 , but also accelerate the consumption of intratumoral glucose to reduce nutrient supply in tumor site. In addition, Se2- further improves the therapeutic effects of CDT by upregulating the reactive oxygen species (ROS) in tumor cells. Meanwhile, the surface modification endows the nanocomposite the good water dispersibility and biocompatibility. Moreover, in vitro and in vivo experiments demonstrate satisfactory anti-cancer therapeutic performance by the synergistic cascade function of CCS@GOx@HA than CDT alone.

Antitumor Effects of Carrier-Free Functionalized Lignin Materials on Human Hepatocellular Carcinoma (HepG2) Cells

Lignin, as an abundant aromatic biopolymer in plants, has great potential for medical applications due to its active sites, antioxidant activity, low biotoxicity, and good biocompatibility. In this work, a simple and ecofriendly approach for lignin fractionation and modification was developed to improve the antitumor activity of lignin. The lignin fraction KL-3 obtained by the lignin gradient acid precipitation at pH = 9-13 showed good cytotoxicity. Furthermore, the cell-feeding lignin after additional structural modifications such as demethylation (DKL-3), sulfonation (SL-3), and demethylsulfonation (DSKL-3) could exhibit higher glutathione responsiveness in the tumor microenvironment, resulting in reactive oxygen species accumulation and mitochondrial damage and eventually leading to apoptosis in HepG2 cells with minimal damage to normal cells. The IC50 values for KL-3, SL-3, and DSKL-3 were 0.71, 0.57, and 0.41 mg/mL, respectively, which were superior to those of other biomass extractives or unmodified lignin. Importantly, in vivo experiments conducted in nude mouse models demonstrated good biosafety and effective tumor destruction. This work provides a promising example of constructing carrier-free functionalized lignin antitumor materials with different structures for inhibiting the growth of human hepatocellular carcinoma (HepG2) cells, which is expected to improve cancer therapy outcomes.

Dual chemodynamic/photothermal therapeutic nanoplatform based on DNA-functionalized prussian blue

The combination of chemodynamic therapy and photothermal therapy has a promising application owing to its impressive anti-cancer effects. However, the degradability of the material and the lack of targeting severely limit its further clinical application. Herein, DNAs containing nucleolin aptamer (AS1411) and different bases sequences were used to functionalize PB NPs for the targeted treatment. Compared to prussian blue, DNA-functionalized prussian blue does not reduce the photothermal properties of prussian blue. Moreover, DNA confers DNA-functionalized prussian blue targeting and higher enzymatic activity, thereby achieving a more effective combination of chemodynamic and photothermal treatment. The therapeutic efficacy of this nanoplatform was evaluated in vivo and in vitro experiments, exhibiting that DNA-functionalized prussian blue nanozyme can maximize the precise control of the therapeutic effect, reduce the toxic and side effects caused by non-specific accumulation on other normal cells, and effectively achieve targeted killing of cancer cells. This work demonstrates that DNA-functionalized prussian blue can improve the efficiency of combined tumor treatment and enhance the application value of prussian blue in tumor treatment, which is expected to provide theoretical support for clinical application.

CuFe Layered Double Hydroxide as Self-Cascade Nanoreactor for Efficient Antibacterial Therapy

Nanozyme-induced reactive oxygen species (ROS)-dependent catalytic therapy has been developed into a powerful strategy against bacterial wound infections. However, the limited endogenous supply or instability of H2O2, the reliance on external stimuli for the generation of ROS, and the highly expressed glutathione (GSH) level make it a challenge to achieve high-performance therapeutic efficiency. In this work, a facile therapeutic strategy against bacterial infections with pristine CuFe layered double hydroxide (LDH) as the self-cascade nanoreactor is proposed without modification or additional energy input. CuFe LDH with an oxidase-like feature can catalyze the generation of multiple ROS, such as 1O2, ·O2-, and H2O2. And the self-generated H2O2 in the cascade nanoreactor could be further in situ transformed to ·OH owing to the peroxidase-like activity. As a result, the cell membrane of bacteria is destroyed, leading to death. Furthermore, its ultrahigh enzyme-like activity of CuFe LDH could effectively promote the breakdown of the biofilm structure. Additionally, the Cu2+-mediated GSH exhaustion of CuFe LDH further avoids the consumption of oxidized ROS and thereby significantly improves the sterilization effect. Finally, the as-prepared CuFe LDH with negligible side effects on normal tissues can be successfully used to eliminate the methicillin-resistant Staphylococcus aureus-infected wounds and accelerate their healing in the mouse model, which paves a new avenue as an antibacterial agent for clinical anti-infective treatment.

Strategies to engineer various nanocarrier-based hybrid catalysts for enhanced chemodynamic cancer therapy

Chemodynamic therapy (CDT) is a newly developed cancer-therapeutic modality that kills cancer cells by the highly toxic hydroxyl radical (˙OH) generated from the in situ triggered Fenton/Fenton-like reactions in an acidic and H2O2-overproduced tumor microenvironment (TME). By taking the advantage of the TME-activated catalytic reaction, CDT enables a highly specific and minimally-invasive cancer treatment without external energy input, whose efficiency mainly depends on the reactant concentrations of both the catalytic ions and H2O2, and the reaction conditions (including pH, temperature, and amount of glutathione). Unfortunately, it suffers from unsatisfactory therapy efficiency for clinical application because of the limited activators (i.e., mild acid pH and insufficient H2O2 content) and overexpressed reducing substance in TME. Currently, various synergistic strategies have been elaborately developed to increase the CDT efficiency by regulating the TME, enhancing the catalytic efficiency of catalysts, or combining with other therapeutic modalities. To realize these strategies, the construction of diverse nanocarriers to deliver Fenton catalysts and cooperatively therapeutic agents to tumors is the key prerequisite, which is now being studied but has not been thoroughly summarized. In particular, nanocarriers that can not only serve as carriers but are also active themselves for therapy are recently attracting increasing attention because of their less risk of toxicity and metabolic burden compared to nanocarriers without therapeutic capabilities. These therapy-active nanocarriers well meet the requirements of an ideal therapy system with maximum multifunctionality but minimal components. From this new perspective, in this review, we comprehensively summarize the very recent research progress on nanocarrier-based systems for enhanced CDT and the strategies of how to integrate various Fenton agents into the nanocarriers, with particular focus on the studies of therapy-active nanocarriers for the construction of CDT catalysts, aiming to guide the design of nanosystems with less components and more functionalities for enhanced CDT. Finally, the challenges and prospects of such a burgeoning cancer-theranostic modality are outlooked to provide inspirations for the further development and clinical translation of CDT.

Multifunctional CuFe2O4@HA as a GSH-depleting nanoplatform for targeted photothermal/enhanced-chemodynamic synergistic therapy

Chemodynamic therapy (CDT), which converts overexpressed hydrogen peroxide (H2O2) in tumor cells to hydroxyl radicals (•OH) by Fenton reactions, is considered a prospective strategy in anticancer therapy. However, the high level of glutathione (GSH) and poor Fenton catalytic efficiency contribute to the suboptimal efficiency of CDT. Herein, we present a multifunctional nanoplatform (CuFe2O4@HA) that can induce GSH depletion and combine with photothermal therapy (PTT) to enhance antitumor efficacy. CuFe2O4@HA nanoparticles could release Cu2+ and Fe3+ after entering tumor cells by targeting hyaluronic acid (HA). Subsequently, Cu2+ and Fe3+ were reduced to Cu+ and Fe2+ by GSH, where Cu+/Fe2+ significantly catalyzed H2O2 to produce a higher level of •OH, and the depletion of GSH disrupted the antioxidant capacity of the tumor. Therefore, depleting GSH substantially enhances the level of •OH in tumor cells. In addition, CuFe2O4@HA nanoparticles have considerable absorption in the near-infrared (NIR) region, which can stimulate excellent PTT effects. More importantly, the heat generated by PTT can further enhance the Fenton catalysis efficiency. In vitro and in vivo experiments have demonstrated the excellent tumor-killing effect of CuFe2O4@HA nanoparticles. This strategy overcomes the problem of insufficient CDT efficacy caused by GSH overexpression and poor catalytic efficiency. Moreover, this versatile nanoplatform provides a reference for self-enhanced CDT and PTT/CDT synergistic targeted therapy.

The Application of Biomedicine in Chemodynamic Therapy: From Material Design to Improved Strategies

Chemodynamic therapy (CDT) has garnered significant interest as an innovative approach for cancer treatment, owing to its notable tumor specificity and selectivity, minimal systemic toxicity and side effects, and absence of the requirement for field stimulation during treatment. This treatment utilizes nanocatalytic medicines containing transitional metals to release metal ions within tumor cells, subsequently initiating Fenton and Fenton-like reactions. These reactions convert hydrogen peroxide (H2O2) into hydroxyl radical (•OH) specifically within the acidic tumor microenvironment (TME), thereby inducing apoptosis in tumor cells. However, insufficient endogenous H2O2, the overexpressed reducing substances in the TME, and the weak acidity of solid tumors limit the performance of CDT and restrict its application in vivo. Therefore, a variety of nanozymes and strategies have been designed and developed in order to potentiate CDT against tumors, including the application of various nanozymes and different strategies to remodel TME for enhanced CDT (e.g., increasing the H2O2 level in situ, depleting reductive substances, and lowering the pH value). This review presents an overview of the design and development of various nanocatalysts and the corresponding strategies employed to enhance catalytic drug targeting in recent years. Additionally, it delves into the prospects and obstacles that lie ahead for the future advancement of CDT.

Heterogeneous-Driven Glutathione Oxidation: Defining the Catalytic Role of Chalcopyrite Nanoparticles

Transition-metal nanocatalysis represents a novel alternative currently experiencing flourishing progress to tackle the tumor microenvironment (TME) in cancer therapy. These nanomaterials aim at attacking tumor cells using the intrinsic selectivity of inorganic catalysts. In addition, special attention to tune and control the release of these transition metals is also required. Understanding the chemical reactions behind the catalytic action of the transition-metal nanocatalysts and preventing potential undesired side reactions caused by acute cytotoxicity of the released ionic species represent another important field of research. Specifically, copper-based oxides may suffer from acute leaching that potentially may induce toxicity not only to target cancer cells but also to nearby cells and tissues. In this work, we propose the synthesis of chalcopyrite (CuFeS₂) nanostructures capable of triggering two key reactions for an effective chemodynamic therapy (CDT) in the heterogeneous phase: (i) glutathione (GSH) oxidation and (ii) oxidation of organic substrates using H₂O₂, with negligible leaching of metals under TME-like conditions. This represents an appealing alternative toward the development of safer copper-iron-based nanocatalytic materials with an active catalytic response without incurring leaching side phenomena.

A dual-function probe with aggregation-induced emission feature for Cu2+ detection and chemodynamic therapy

Herein, a fluorescent probe (named TPACP) with aggregation-induced emission (AIE) feature was developed and utilized for the selective detection of Cu²⁺ with high sensitivity and fast-response. The resultant TPACP@Cu²⁺ complexes from coordination of TPACP with Cu²⁺ can also be potentially applied for chemodynamic and photodynamic therapy.

Dual-Oxygenation/Dual-Fenton Synergistic Photothermal/Chemodynamic/Starvation Therapy for Tumor Treatment

Due to the complexity of tumor pathogenesis and the heterogeneity of the tumor microenvironment (TME), it is difficult to obtain satisfactory efficacy with a single therapy. In this study, a hyaluronic acid (HA)-modified ruthenium nanoaggregate (RuNA) and glucose oxidase (GOD) -loaded manganese dioxide (MnO₂) nanoflowers (MRG@HA) have been prepared. RuNA and MnO₂ nanoflowers can generate O₂ in TME, alleviating tumor tissue hypoxia. RuNA is a good photothermal agent for high-temperature ablation of solid tumors under infrared laser irradiation. GOD consumes glucose in the presence of O₂ and converts it into glucuronic acid and hydrogen peroxide, reducing tumor nutrient supply while promoting Fenton-like reactions of MnO₂ nanoflowers and RuNA to produce cytotoxic hydroxyl radicals. MRG@HA can also actively target tumor cells through the affinity of HA and CD44 receptor to improve the antitumor effect. In vitro and in vivo studies have confirmed the synergistic effect of MRG@HA with tumor photothermal/chemodynamic/starvation therapy, showing its great potential for clinical application in tumor therapy.

Starvation-assisted and photothermal-thriving combined chemo/chemodynamic cancer therapy with PT/MR bimodal imaging

Chemodynamic therapy (CDT) reflects a novel reactive oxygen species (ROS)-related cancer therapeutic approach. However, CDT monotherapy is often limited by weak efficacy and insufficient endogenous H₂O₂. Herein, a multifunctional combined bioreactor (MnFe-LDH/MTX@GOx@Ta, MMGT) relying on MnFe-layered double hydroxide (MnFe-LDH) loaded with methotrexate (MTX) and coated with glucose oxidase (GOx)/tannin acid (Ta) is established for applications in H₂O₂ self-supply and photothermal enhanced chemo/chemodynamic combined therapy along with photothermal (PT) /magnetic resonance (MR) dual-modality imaging ability for cancer treatment. Once internalized into tumor cells, MMGT achieves starvation therapy by catalyzing the oxidation of glucose with GOx, accompanied by the regeneration of H₂O₂, enabling a Fenton-like reaction to accomplish GOx catalytic amplified CDT. Moreover, MMGT manifests significant tumor-killing ability through improved CDT performance with outstanding photothermal conversion efficiency (η = 52.2%) under 808 nm laser irradiation. In addition, the release of Mn²⁺ from MnFe-LDH in a solid tumor can significantly enhance T₁-contrast MR imaging signals. Combined with MnFe-LDH-induced PT imaging under 808 nm laser irradiation, a dual-modality imaging directed theranostic nanoplatform has been developed. The present study provides a new strategy to design H₂O₂ self-supply and ROS evolving NIR light-absorption theranostic nanoagent for highly efficient and combined chemo/chemodynamic cancer treatment.

Oxygen vacancy-enhanced catalytic activity of hyaluronic acid covered-biomineralization nanozyme for reactive oxygen species-augmented antitumor therapy

Insufficient hydrogen peroxide content in tumor cells, unsuitable pH and low efficiency of commonly used metal catalysts severely affect the efficiency of chemodynamic therapy, resulting in unsatisfactory efficacy of chemodynamic therapy alone. For this purpose, we designed a composite nanoplatform capable of targeting tumors and selectively degrading in the tumor microenvironment (TME) to address these issues. In this work, we synthesized Au@Co₃O₄ nanozyme inspired by crystal defect engineering. The addition of Au determines the formation of oxygen vacancies, accelerates electron transfer, and enhances redox activity, thus significantly enhancing the superoxide dismutase (SOD)-like and catalase (CAT)-like catalytic activities of the nanozyme. Subsequently, we camouflaged the nanozyme using a biomineralized CaCO₃ shell to avoid damage to normal tissues by the nanozyme while effectively encapsulating the photosensitizer IR820, and finally the tumor targeting ability of the nanoplatform was enhanced by the modification of hyaluronic acid. Under near-infrared (NIR) light irradiation, the Au@Co₃O₄@CaCO₃/IR820@HA nanoplatform not only visualizes the treatment with multimodal imaging, but also plays a photothermal sensitizing role through various strategies, while enhancing the enzyme catalytic activity, cobalt ion-mediated chemodynamic therapy (CDT) and IR820-mediated photodynamic therapy (PDT), and achieving the synergistic enhancement of reactive oxygen species (ROS) generation.

Repolarizing tumor-associated macrophages by layered double hydroxide-based deacidification agent for tumor chemodynamic therapy and immunotherapy

Tumor-associated macrophages (TAMs)-mediated immunotherapy has attracted extensive attention in tumor elimination. However, the acidic tumor microenvironment (TME) severely limits the phenotype of TAMs to pro-tumoral M2 state, suppressing immune response efficacy against tumors. Herein, novel poly(acrylic acid) (PAA)-coated, doxorubicin (DOX)-loaded layered double hydroxide (LDH) nanosheets (NSs) were developed as deacidification agent to repolarize TAMs from pro-tumoral M2 to anti-tumoral M1 phenotype for tumor elimination through combined chemodynamic therapy and immunotherapy. When located in tumor regions, LDH-PAA@DOX NSs display good deacidification capacity to neutralize acidic TME, achieving the repolarization of TAMs to M1 phenotype and further activating CD8+ T cells. During the deacidification process, these NSs are acid-responsive and degrade to release Fe3+ and DOX. The former can be reduced to Fe2+ by intracellular glutathione, meanwhile disrupting the antioxidant defense system of tumor cells. The latter can damage tumor cells directly and further stimulate the production of hydrogen peroxide, providing abundant substrate for the Fenton reaction. Toxic hydroxyl radical is excessively produced through Fe2+-mediated Fenton reaction to cause intratumoral oxidative stress. In vivo data revealed that significant tumor elimination can be achieved under LDH-PAA@DOX treatment. This work not only provides a promising paradigm for neutralizing acidic TME using deacidification agent but also highlights the effectiveness of combined chemodynamic therapy and immunotherapy in tumor treatment.

Monolayer LDH Nanosheets with Ultrahigh ICG Loading for Phototherapy and Ca2+-Induced Mitochondrial Membrane Potential Damage to Co-Enhance Cancer Immunotherapy

Tumor recurrence and metastasis are the main causes of cancer mortality; traditional chemotherapeutic drugs have severe toxicity and side effects in cancer treatment. To overcome these issues, here, we present a pH-responsive, self-destructive intelligent nanoplatform for magnetic resonance/fluorescence dual-mode image-guided mitochondrial membrane potential damage (MMPD)/photodynamic (PDT)/photothermal (PTT)/immunotherapy for breast cancer treatment with external near infrared (NIR) light irradiation. To do so, we construct multifunctional monolayer-layered double hydroxide (LDH) nanosheets (MICaP), co-loading indocyanine green (ICG) with ultrahigh loading content realized via electrostatic interactions, and calcium phosphate (Ca3(PO4)2) coating via biomineralization. Such a combined therapy design is featured by the outstanding biocompatibility and provokes immunogenic cell death (ICD) of tumors toward cancer immunotherapy. The active transport of excess Ca2+ released from pH-sensitive Ca3(PO4)2 can induce MMPD of tumor cells to minimize oxygen consumption in the tumor microenvironment (TME). The presence of ICG not only generates singlet oxygen (1O2) to induce apoptosis by photodynamic therapy (PDT) but also initiates tumor cell necrosis by photothermal therapy (PTT) under near-infrared (NIR) light radiation. Eventually, the immune response generated by MMPD/PDT/PTT greatly promotes a cytotoxic T lymphocyte (CTL) response that can limit tumor growth and metastasis. Both in vitro and in vivo studies indeed illustrate outstanding antitumor efficiency and outcomes. We anticipate that such precisely designed nanoformulations can contribute in a useful and advantageous way that is conducive to explore novel nanomedicines with notable values in antitumor therapy.

Potential of Copper and Copper Compounds for Anticancer Applications

Inducing cancer cell death has always been a research hotspot in life sciences. With the continuous deepening and diversification of related research, the potential value of metal elements in inducing cell death has been explored. Taking iron as an example, ferroptosis, mainly characterized by increasing iron load and driving the production of large amounts of lipid peroxides and eventually leading to cell death, has recently attracted great interest in the cancer research community. After iron, copper, a trace element, has received extensive attention in cell death, especially in inducing tumor cell death. Copper and its complexes can induce autophagy or apoptosis in tumor cells through a variety of different mechanisms of action (activation of stress pathways, arrest of cell cycle, inhibition of angiogenesis, cuproptosis, and paraptosis), which are promising in cancer therapy and have become new hotspots in cancer treatment research. This article reviews the main mechanisms and potential applications of novel copper and copper compound-induced cell death, focusing on copper compounds and their anticancer applications.

Mesoporous polydopamine-based nanoplatform for enhanced tumor chemodynamic therapy through the reducibility weakening strategy

Polydopamine (PDA)-based Fenton agents attract increasing attention in tumor photothermal-enhanced chemodynamic therapy (CDT) due to their good biocompatibility and excellent loading capacity. However, PDA tends to eliminate the Fenton reaction-generated hydroxyl radical (∙OH) by its strong reducibility, which is an intractable hinder to the efficacy of CDT that need to be solved. Herein, a kind of mesoporous PDA-gold-manganese dioxide (MPDA-Au-MnO₂, MPAM) nanoplatform was constructed for photothermal-enhanced CDT against tumor through the reducibility weakening strategy. The reducibility of original MPDA is effectively weakened by the oxidation role of HAuCl₄ and KMnO₄ during the preparation process, reducing the ∙OH scavenging ability of MPDA and benefiting the production of ∙OH. The MnO₂ shell could react with GSH to release Mn²⁺, acting as the Fenton-like agent to generate ∙OH. The exposed Au NPs can further deplete GSH through the Au-S bond interaction. MPDA acts as the photothermal agent to generate hyperthermia under laser irradiation. MPAM shows excellent intracellular GSH scavenging ability and enhanced ∙OH production ability. After intravenous injection, MPAM can significantly suppress the growth of tumors under laser irradiation, meanwhile showing good biosafety. The developed MPDA-based nanoplatform can not only display good potential in further tumor treatments but also provide meaningful enlightenment for developing high-performance PDA or MPDA-based nanoplatforms in CDT-related applications.

All-in-one CoFe2O4@Tf nanoagent with GSH depletion and tumor-targeted ability for mutually enhanced chemodynamic/photothermal synergistic therapy

In the complex and severe tumor microenvironment, the antitumor efficiency of nanomedicines is significantly limited by their low-efficacy monotherapy, non-tumor targeting, and systemic toxicity. Herein, to achieve tumor-targeted and enhanced chemodynamic/photothermal therapy (CDT/PTT), we fabricated an "all-in-one" biocompatible transferrin-loaded cobalt ferrate nanoparticle (CoFe₂O₄@Tf (CFOT)) with multiple functions by a simple solvothermal method and the following transferrin (Tf) functionalization. Upon exposure to 808 nm laser irradiation, CFOT, as a novel photothermal agent, exhibited outstanding phototherapeutic activity because of its excellent photothermal conversion efficiency (η = 46.5%) for high-performance PTT. Moreover, CFOT with multiple redox pairs could efficiently convert endogenous H₂O₂ to hazardous hydroxyl radicals (˙OH) via Fenton reactions while scavenging overexpressed GSH in the tumor microenvironment to realize self-reinforcing CDT. Importantly, CFOT undergoes a promoted Fenton-type reaction upon increasing the temperature under a photothermal effect and could augment PTT by high-level ˙OH, exhibiting a considerably enhanced synergistic therapeutic effect. In vitro and in vivo experimental results demonstrated that CFOT has good potential as an "all-in-one" nanoagent to combine photothermal, chemodynamic, and tumor targeting for efficient tumor elimination.

Cisplatin-loaded metal–phenolic network with photothermal-triggered ROS generation for chemo-photothermal therapy of cancer

Developing multifunctional composites has received widespread attention for cancer treatment. Herein, a metal–phenolic network (MPN)-based composite loading with chemotherapy agents (TAFP) exhibits high anti-tumor therapeutic efficacy via photothermal therapy (PTT), chemo-dynamic therapy (CDT), and chemotherapy. The nanocomposite was formed by mixing the chemotherapeutic drugs (cisplatin, DDP) into the tannic acid (TA) and Fe3+ network (TAFe) to integrate the synergistic effect of PTT, CDT, and chemotherapy. Due to the acidic tumor microenvironment, the active substances could be released with the degradation of the metal–phenolic network, and the released DDP would induce the chemotherapy. More importantly, the released TA under the acidic environment could increase iron bioavailability by converting Fe3+ to Fe2+, which converts hydrogen peroxide (H2O2) to highly toxic hydroxyl radical via the Fenton reaction. Meanwhile, the heat generated from TAFP after near-infrared (NIR) laser irradiation could enhance the therapeutic effect of CDT and chemotherapy. Furthermore, the composite exhibited unique anticancer efficacy in vivo with low toxicity. Collectively, this work may facilitate the development of metal–phenolic network-based photothermal agents for clinic anti-tumor applications.

[Cuprous oxide nanoparticles-based photothermal and chemodynamic synergistic therapy inhibits proliferation and migration of gastric cancer cells in vitro]

OBJECTIVE

To investigate the physicochemical characterization of cuprous oxide (Cu2O) nanoparticles and assess its antitumor effect against gastric cancer cells in vitro.

METHODS

The morphology, particle size and Fenton-like properties of Cu2O nanoparticles were analyzed using transmission electron microscopy (TEM), dynamic light scattering (DLS), zeta potential analysis and ultraviolet absorption spectroscopy. CCK-8 assay and Transwell experiments were used for evaluating the in vitro anti-tumor effect of the nanometers in gastric cancer cells.

RESULTS

The prepared Cu2O nanoparticles had a quasi-circular structure with a diameter of about 100 nm. The temperature of the nanoparticles increased from 25 to 50 ℃ after irradiation with near-infrared light (NIR, 0.5W/cm2) for 5 min. At a nearly neutral pH (pH=6.5), the nanoparticles catalyzed the generation of a large amount of reactive oxygen species (ROS). CCK-8 assay and Transwell experiment showed that Cu2O nanoparticles concentration-dependently inhibited the proliferation, invasion and migration of gastric cancer cells.

CONCLUSION

Cu2O nanoparticles have good photothermal and chemokinetic properties with a strong anti-tumor effect, and can potentially serve as a new therapeutic agent for gastric cancer treatment.

Sorafenib-Loaded Copper Peroxide Nanoparticles with Redox Balance Disrupting Capacity for Enhanced Chemodynamic Therapy against Tumor Cells

Chemodynamic therapy (CDT) is a promising hydroxyl radical (•OH)-mediated tumor therapeutic method with desirable tumor specificity and minimal side effects. However, the efficiency of CDT is restricted by the pH condition, insufficient H₂O₂ level, and overexpressed reductive glutathione (GSH), making it challenging to solve these problems simultaneously to improve the efficacy of CDT. Herein, a kind of polyvinylpyrrolidone-stabilized, sorafenib-loaded copper peroxide (CuO₂-PVP-SRF) nanoparticle (NPs) was designed and developed for enhanced CDT against tumor cells through the synergetic pH-independent Fenton-like, H₂O₂ self-supplying, and GSH depletion strategy. The prepared CuO₂-PVP-SRF NPs can be uptaken by 4T1 cells to specifically release Cu²⁺, H₂O₂, and SRF under acidic conditions. The intracellular GSH can be depleted by SRF-induced system xc^- dysfunction and Cu²⁺-participated redox reaction, causing the inactivation of GPX4 and generating Cu⁺. A great amount of •OH was produced in this reducing capacity-disrupted condition by the Cu⁺-mediated Fenton-like reaction, causing cell apoptosis and lipid hydroperoxide accumulation-induced ferroptosis. They display an excellent 4T1 cell killing outcome through the improved •OH production capacity. The CuO₂-PVP-SRF NPs display elevated therapeutic efficiency of CDT and show good promise in further tumor treatment applications.

Unveiling the interplay between homogeneous and heterogeneous catalytic mechanisms in copper-iron nanoparticles working under chemically relevant tumour conditions

The present work sheds light on a generally overlooked issue in the emerging field of bio-orthogonal catalysis within tumour microenvironments (TMEs): the interplay between homogeneous and heterogeneous catalytic processes. In most cases, previous works dealing with nanoparticle-based catalysis in the TME focus on the effects obtained (e.g. tumour cell death) and attribute the results to heterogeneous processes alone. The specific mechanisms are rarely substantiated and, furthermore, the possibility of a significant contribution of homogeneous processes by leached species - and the complexes that they may form with biomolecules - is neither contemplated nor pursued. Herein, we have designed a bimetallic catalyst nanoparticle containing Cu and Fe species and we have been able to describe the whole picture in a more complex scenario where both homogeneous and heterogeneous processes are coupled and fostered under TME relevant chemical conditions. We investigate the preferential leaching of Cu ions in the presence of a TME overexpressed biomolecule such as glutathione (GSH). We demonstrate that these homogeneous processes initiated by the released by Cu-GSH interactions are in fact responsible for the greater part of the cell death effects found (GSH, a scavenger of reactive oxygen species, is depleted and highly active superoxide anions are generated in the same catalytic cycle). The remaining solid CuFe nanoparticle becomes an active catalyst to supply oxygen from oxygen reduced species, such as superoxide anions (by-product from GSH oxidation) and hydrogen peroxide, another species that is enriched in the TME. This activity is essential to sustain the homogeneous catalytic cycle in the oxygen-deprived tumour microenvironment. The combined heterogeneous-homogeneous mechanisms revealed themselves as highly efficient in selectively killing cancer cells, due to their higher GSH levels compared to healthy cell lines.

Layered double hydroxide-based nanomaterials for biomedical applications

Against the backdrop of increased public health awareness, inorganic nanomaterials have been widely explored as promising nanoagents for various kinds of biomedical applications. Layered double hydroxides (LDHs), with versatile physicochemical advantages including excellent biocompatibility, pH-sensitive biodegradability, highly tunable chemical composition and structure, and ease of composite formation with other materials, have shown great promise in biomedical applications. In this review, we comprehensively summarize the recent advances in LDH-based nanomaterials for biomedical applications. Firstly, the material categories and advantages of LDH-based nanomaterials are discussed. The preparation and surface modification of LDH-based nanomaterials, including pristine LDHs, LDH-based nanocomposites and LDH-derived nanomaterials, are then described. Thereafter, we systematically describe the great potential of LDHs in biomedical applications including drug/gene delivery, bioimaging diagnosis, cancer therapy, biosensing, tissue engineering, and anti-bacteria. Finally, on the basis of the current state of the art, we conclude with insights on the remaining challenges and future prospects in this rapidly emerging field.