Sm/Co-Doped Silica-Based Nanozymes Reprogram Tumor Microenvironment for ATP-Inhibited Tumor Therapy

Wintersweet-like Nanohybrids of Titanium-doped Cerium Vanadate Loaded with Polypyrrole for Tumor Theranostic

Compromises between enhanced on-targeting reactivity and precise real-time monitoring in the tumor microenvironment (TME) are the main roadblocks for catalytic cancer therapy. The hallmark of a high level of hydrogen peroxide (H2O2) and acidic extracellular environment of the hypoxia solid tumor can underpin therapeutic and tracking performance. Herein, this work provides an activatable wintersweet-like nanohybrid consisting of titanium (Ti) doped cerium vanadate nanorods with the modification of polypyrrole (PPy) nanoparticles (CeVO4-Ti@PPy) for combinatorial therapies of breast carcinoma. The Ti dopants in the size-controllable CeVO4 nanorods lower the energy barrier (0.5 eV) of the rate-determining steps and elaborate peroxidase-like (POD-like) activities to improve the generation of toxic hydroxyl radical (·OH) according to the density functional theory (DFT) calculation. The multiple enzyme-like activities, including the intrinsic glutathione peroxidase (GPx) and catalase (CAT), achieve a record-high therapeutic efficiency. Coupling this oxidative stress with the photothermal effects of PPy enables enhanced catalytic tumor necrosis. The exterior PPy heterogeneous structure can be further doped with protons in the local acidic environment to intensify photoacoustic signals, allowing the non-invasive accurate tracking of tumors. The theranostic performance displayed negligible attenuated signals in near-infrared (NIR) windows. This organic-inorganic nanohybrid with a heterogeneous structure provides the potential to improve the overall outcomes of catalytic therapy.

Transition-Metal-Based Nanozymes: Synthesis, Mechanisms of Therapeutic Action, and Applications in Cancer Treatment

Cancer, as one of the leading causes of death worldwide, drives the advancement of cutting-edge technologies for cancer treatment. Transition-metal-based nanozymes emerge as promising therapeutic nanodrugs that provide a reference for cancer therapy. In this review, we present recent breakthrough nanozymes for cancer treatment. First, we comprehensively outline the preparation strategies involved in creating transition-metal-based nanozymes, including hydrothermal method, solvothermal method, chemical reduction method, biomimetic mineralization method, and sol-gel method. Subsequently, we elucidate the catalytic mechanisms (catalase (CAT)-like activities), peroxidase (POD)-like activities), oxidase (OXD)-like activities) and superoxide dismutase (SOD)-like activities) of transition-metal-based nanozymes along with their activity regulation strategies such as morphology control, size manipulation, modulation, composition adjustment and surface modification under environmental stimulation. Furthermore, we elaborate on the diverse applications of transition-metal-based nanozymes in anticancer therapies encompassing radiotherapy (RT), chemodynamic therapy (CDT), photodynamic therapy (PDT), photothermal therapy (PTT), sonodynamic therapy (SDT), immunotherapy, and synergistic therapy. Finally, the challenges faced by transition-metal-based nanozymes are discussed alongside future research directions. The purpose of this review is to offer scientific guidance that will enhance the clinical applications of nanozymes based on transition metals.

PBA-Derived Heteroatom-Doped Mesoporous Graphitic Spheroids as Peroxidase Nanozyme for In Vitro Tumor Cells Detection

Inspired by the two kinds of naturally occurring peroxidases (POD) with vanadium or heme (iron)-based active catalytic centers, we have developed a dual metal-based nanozyme with dual V and Fe-based active catalytic centers. Co-doping of graphene with heteroatoms has a synergistic effect on the catalytic properties of the nanomaterial as the distances of migration of the substrates drastically reduce. However, a few studies have reported the codoping of heterometallic elements in the graphene structure due to the complexity of the synthesis procedures. Herein, we report the synthesis of in situ doped bimetallic VNFe@C mesoporous graphitic spheroids nanozyme via pyrolysis without the assistance of any template assisted method. The Prussian-blue analog-based precursor material was synthesized by a facile one-step low-temperature synthesis procedure. The bimetallic spheroids showed an excellent affinity toward H2O2, with a Km value of 0.26 mM when compared to 0.436 for the natural POD, which is much better than the natural POD, which was utilized to detect tumor cells in vitro through the intracellular H2O2 produced by these cells under high oxidative stress. The VNFe@C mesoporous spheroids generate dual reactive oxygen species, including the •OH and •O2H- radicals, in the presence of H2O2, which are responsible for the POD-like activity of these nanozymes, while the bimetallic V/Fe doping plays a synergistic role in the enhancement of the activity of codoped graphitic spheroids.

Multifunctional nanoplatform based on tetragonal BaTiO3-Au@polydopamine for computed tomography imaging-guided photothermal synergistic and enhanced piezocatalytic cancer therapy

Non-centrosymmetric tetragonal barium titanate nanocrystals have the potential to serve as piezoelectric catalysts in cancer therapy. When exposed to ultrasound irradiation, BaTiO3 can generate reactive oxygen species with a noninvasive and deep tissue-penetrating approach. However, the application of BaTiO3 in cancer nanomedicine is limited by their biosafety, biocompatibility, and dosage efficiency. To explore the potential application of BaTiO3 in nanomedical cancer treatment, we introduced ultra-small Au nanoparticles onto the surface of BaTiO3 to enhance the piezoelectric catalytic performance. Additionally, we also coated the BaTiO3 with polydopamine to improve their biosafety and biocompatibility. This led to the preparation of a novel multifunctional BaTiO3-based nanoplatform called BTAPs. In vitro and in vivo experiments demonstrated that the incorporation of Au dopants and polydopamine coating successfully improved the piezoelectric catalysis properties and biocompatibility of BaTiO3. Compared with unmodified BaTiO3, BTAPs achieved a similar piezoelectric catalytic effect at a low dose (0.3 mg ml-1 in vitro and 10 mg kg-1 in vivo). Moreover, BTAPs also exhibited enhanced properties in computed tomography imaging and photothermal effects in vivo. Therefore, BTAPs offer valuable insights into the advantages and limitations of piezoelectric catalytic nanomedicine in cancer treatment.

Sulfonated vitamin K3 mediated bimetallic metal-organic framework for multistage augmented cancer therapy

Chemodynamic therapy (CDT) relying on Fenton reaction has emerged as a promising strategy for tumor treatment. However, its clinical efficacy is hindered by the inadequate reactive oxygen species (ROS) and the potential cytotoxicity towards normal cells. To address these challenges, we have successfully developed a multistage augmented cancer therapy system based on bimetallic metal-organic framework (BMOF) that amplifies ROS and facilitates tumor-specific therapeutic effects. By employing a simple one-pot self-assembly approach, we synthesized SVK3@ZnCo-ZIF in which sulfonated vitamin K3 (SVK3) was encapsulated within ZnCo-ZIF BMOF. The results revealed that the incorporation of Zn atoms significantly diluted the Fenton activity of Co atoms towards normal cells. Notably, SVK3@ZnCo-ZIF underwent pH-controlled decomposition triggered by the tumor microenvironment (TME), thus releasing SVK3, Co2+ and Zn2+. Specifically, the H2O2 levels in tumors was effectively elevated by the interaction of SVK3 with NAD(P)H quinone oxidoreductase-1 (NQO-1). It thus enhanced the Fenton activity of Co2+. Moreover, the release of Zn2+ ions can induce cellular dysfunction and mitochondrial damage, thereby promoting the generation of ROS and subsequent cell death. The synergistic combination of CDT, SVK3 chemotherapy, and Zn2+-interfered therapy greatly facilitated apoptosis of tumor cells. Collectively, our investigations demonstrate the efficacy of such system in selectively inducing toxicity in cancer cells while minimizing detrimental effects on normal cells.

PdMo nanoflowers for endogenous/exogenous-stimulated nanocatalytic therapy

The clinical application of reactive oxygen species (ROS)-mediated tumor treatment has been critically limited by inefficient ROS generation. Herein, we rationally synthesized and constructed the three-dimensional PdMo nanoflowers through a one-pot solvothermal reduction method for elaborately regulated peroxidase-like enzymatic activity and glutathione peroxidase-like enzymatic activity, to promote oxidation ROS evolvement and antioxidation glutathione depletion for achieving intensive ROS-mediated tumor therapy. The three-dimensional superstructure composed of two-dimensional nanosheet subunits can solve the issues by avoiding the appearance of tightly stacked crystalline nanostructures. Significantly, Mo is chosen as a second metal to alloy with Pd because of its more chemical valence and negative ionization energy than Pd for improved electron transfer efficiencies and enhanced enzyme-like activities. In addition, the photothermal effect generated by PdMo nanoflowers could also enhance its enzymatic activities. Thus, this work provides a promising paradigm for achieving highly ROS-mediated tumor therapeutic efficacy by regulating the multi-enzymatic activities of Pd-based nanoalloys.

Preclinical Assessment of Enhanced Chemodynamic Therapy by an FeMnOx-Based Nanocarrier: Tumor-Microenvironment-Mediated Fenton Reaction and ROS-Induced Chemotherapeutic for Boosted Antitumor Activity

In recent studies, iron-containing Fenton nanocatalysts have demonstrated significant promise for clinical use due to their effective antitumor activity and low cytotoxicity. A new approach was reported in this work utilizing cation exchange synthesis to fabricate FeMnOx nanoparticles (NPs) that boost Fenton reactions and responses to the tumor microenvironment (TME) for chemodynamic therapy (CDT) and chemotherapy (CT). Within the TME, the redox metal pair of Fe2+/Mn2+ helps break down endogenous hydrogen peroxide (H2O2) into very harmful hydroxyl radicals (•OH) while simultaneously deactivating glutathione (GSH) to boost CDT performance. To further enhance the therapeutic potential, FeMnOx NPs were encapsulated with thioketal-linked camptothecin (CPT-TK-COOH), a reactive oxygen species (ROS)-responsive prodrug, achieving a high CPT-loading capacity of up to 51.1%. Upon ROS generation through the Fenton reaction, the prodrug TK linkage was disrupted, releasing 80% of the CPT payload within 48 h. Notably, FeMnOx@CPT exhibited excellent dual-modal imaging capabilities, enabling magnetic resonance and fluorescence imaging for image-guided therapy. In vitro studies showed the cytocompatibility of FeMnOx NPs using MDA-Mb-231 and 4T1 cells, but in the presence of H2O2, they induced significant cytotoxicity, resulting in 80% cell death through CDT and CT effects. Upon intravenous administration, FeMnOx@CPT displayed remarkable tumor accumulation, which enhanced tumor suppression in xenografts through improved CDT and CT effects. Moreover, no significant adverse effects were observed in the FeMnOx NP-treated animals. In the current study, the FeMnOx@CPT anticancer platform, with its boosted •OH-producing capability and ROS-cleavable drug release, has been validated utilizing in vitro and animal studies, suggesting its capacity as a viable strategy for clinical trials.

AuPt-Loaded Cu-Doped Polydopamine Nanocomposites with Multienzyme-Mimic Activities for Dual-Modal Imaging-Guided and Cuproptosis-Enhanced Photothermal/Nanocatalytic Therapy

Nanocatalytic therapy (NCT) has made great achievements in tumor treatments due to its remarkable enzyme-like activities and high specificity. Nevertheless, the limited types of nanozymes and undesirable tumor microenvironments (TME) greatly weaken the therapeutic efficiency. Developing a combination therapy integrating NCT and other strategies is of great significance for optimal treatment outcomes. Herein, a AuPt-loaded Cu-doped polydopamine nanocomposite (AuPt@Cu-PDA) with multiple enzyme-like activities was rationally designed, which integrated photothermal therapy (PTT) and NCT. The peroxidase (POD)-like activity of AuPt@Cu-PDA can catalyze hydrogen peroxide (H2O2) into ·OH, and the catalase (CAT)-mimic activity can decompose H2O2 into O2 to alleviate hypoxia of TME, and O2 can be further converted into toxic ·O2- by its oxidase (OXD)-mimic activity. In addition, Cu2+ in AuPt@Cu-PDA can effectively consume GSH overexpressed in tumor cells. The boosting of reactive oxygen species (ROS) and glutathione (GSH) depletion can lead to severe oxidative stress, which can be enhanced by its excellent photothermal performance. Most importantly, the accumulation of Cu2+ can disrupt copper homeostasis, promote the aggregation of lipoylated dihydrolipoamide S-acetyltransferase (DLAT), disrupt the mitochondrial tricarboxylic acid (TCA) cycle, and finally result in cuproptosis. Collectively, photothermal and photoacoustic imaging (PTI/PAI)-guided cuproptosis-enhanced NCT/PTT can be achieved. This work may expand the application of nanozymes in synergistic therapy and provide new insights into cuproptosis-related therapeutic strategies.