A Self-Catalytic NO/O2 Gas-Releasing Nanozyme for Radiotherapy Sensitization through Vascular Normalization and Hypoxia Relief.

Radiotherapy (RT), essential for treating various cancers, faces challenges from tumor hypoxia, which induces radioresistance. A tumor-targeted "prosthetic-Arginine" coassembled nanozyme system, engineered to catalytically generate nitric oxide (NO) and oxygen (O2) in the tumor microenvironment (TME), overcoming hypoxia and enhancing radiosensitivity is presented. This system integrates the prosthetic heme of nitric oxide synthase (NOS) and catalase (CAT) with NO-donating Fmoc-protected Arginine and Ru3+ ions, creating HRRu nanozymes that merge NOS and CAT functionalities. Surface modification with human heavy chain ferritin (HFn) improves the targeting ability of nanozymes (HRRu-HFn) to tumor tissues. In the TME, strategic arginine incorporation within the nanozyme allows autonomous O2 and NO release, triggered by endogenous hydrogen peroxide, elevating NO and O2 levels to normalize vasculature and improve blood perfusion, thus mitigating hypoxia. Employing the intrinsic O2-transporting ability of heme, HRRu-HFn nanozymes also deliver O2 directly to the tumor site. Utilizing esophageal squamous cell carcinoma as a tumor model, the studies reveal that the synergistic functions of NO and O2 production, alongside targeted delivery, enable the HRRu-HFn nanozymes to combat tumor hypoxia and potentiate radiotherapy. This HRRu-HFn nanozyme based approach holds the potential to reduce the radiation dose required and minimize side effects associated with conventional radiotherapy.

Enhancing Nanobody Immunoassays through Ferritin Fusion: Construction of a Salmonella-Specific Fenobody for Improved Avidity and Sensitivity.

Nanobodies (Nbs) serve as powerful tools in immunoassays. However, their small size and monovalent properties pose challenges for practical application. Multimerization emerges as a significant strategy to address these limitations, enhancing the utilization of nanobodies in immunoassays. Herein, we report the construction of a Salmonella-specific fenobody (Fb) through the fusion of a nanobody to ferritin, resulting in a self-assembled 24-valent nanocage-like structure. The fenobody exhibits a 35-fold increase in avidity compared to the conventional nanobody while retaining good thermostability and specificity. Leveraging this advancement, three ELISA modes were designed using Fb as the capture antibody, along with unmodified Nb422 (FbNb-ELISA), biotinylated Nb422 (FbBio-ELISA), and phage-displayed Nb422 (FbP-ELISA) as the detection antibody, respectively. Notably, the FbNb-ELISA demonstrates a detection limit (LOD) of 3.56 × 104 CFU/mL, which is 16-fold lower than that of FbBio-ELISA and similar to FbP-ELISA. Moreover, a fenobody and nanobody sandwich chemiluminescent enzyme immunoassay (FbNb-CLISA) was developed by replacing the TMB chromogenic substrate with luminal, resulting in a 12-fold reduction in the LOD. Overall, the ferritin-displayed technology represents a promising methodology for enhancing the detection performance of nanobody-based sandwich ELISAs, thereby expanding the applicability of Nbs in food detection and other fields requiring multivalent modification.

Nanomaterial-Based Strategies for Attenuating T-Cell-Mediated Immunodepression in Stroke Patients: Advancing Research Perspectives.

This review article discusses the potential of nanomaterials in targeted therapy and immunomodulation for stroke-induced immunosuppression. Although nanomaterials have been extensively studied in various biomedical applications, their specific use in studying and addressing immunosuppression after stroke remains limited. Stroke-induced neuroinflammation is characterized by T-cell-mediated immunodepression, which leads to increased morbidity and mortality. Key observations related to immunodepression after stroke, including lymphopenia, T-cell dysfunction, regulatory T-cell imbalance, and cytokine dysregulation, are discussed. Nanomaterials, such as liposomes, micelles, polymeric nanoparticles, and dendrimers, offer advantages in the precise delivery of drugs to T cells, enabling enhanced targeting and controlled release of immunomodulatory agents. These nanomaterials have the potential to modulate T-cell function, promote neuroregeneration, and restore immune responses, providing new avenues for stroke treatment. However, challenges related to biocompatibility, stability, scalability, and clinical translation need to be addressed. Future research efforts should focus on comprehensive studies to validate the efficacy and safety of nanomaterial-based interventions targeting T cells in stroke-induced immunosuppression. Collaborative interdisciplinary approaches are necessary to advance the field and translate these innovative strategies into clinical practice, ultimately improving stroke outcomes and patient care.

Structure-Guided Design of Ferritin-Platinum Prodrugs for Targeted Therapy of Esophageal Squamous Cell Carcinoma.

Due to its intrinsic tumor-targeting attribute, limited immunogenicity, and cage architecture, ferritin emerges as a highly promising nanocarrier for targeted drug delivery. In the effort to develop ferritin cage-encapsulated cisplatin (CDDP) as a therapeutic agent, we found unexpectedly that the encapsulation led to inactivation of the drug. Guided by the structural information, we deciphered the interactions between ferritin cages and CDDP, and we proposed a potential mechanism responsible for attenuating the antitumor efficacy of CDDP encapsulated within the cage. Six platinum prodrugs were then designed to avoid the inactivation. The antitumor activities of these ferritin-platinum prodrug complexes were then evaluated in cells of esophageal squamous cell carcinoma (ESCC). Compared with free CDDP, the complexes were more effective in delivering and retaining platinum in the cells, leading to increased DNA damage and enhanced cytotoxic action. They also exhibited improved pharmacokinetics and stronger antitumor activities in mice bearing ESCC cell-derived xenografts as well as patient-derived xenografts. The successful encapsulation also illustrates the critical significance of comprehending the interactions between small molecular drugs and ferritin cages for the development of precision-engineered nanocarriers.

Catalase-templated nanozyme-loaded microneedles integrated with polymyxin B for immunoregulation and antibacterial activity in diabetic wounds.

Diabetic wounds are characterized by chronic trauma, with long-term non-healing attributed to persistent inflammation and recurrent bacterial infections. Exacerbation of the inflammatory response is largely due to increased levels of reactive oxygen species (ROS). In this study, catalase (CAT) was used as a biological template to synthesize nanozyme-supported natural enzymes (CAT-Mn(SH)x) using a biomimetic mineralization method. Subsequently, polymyxin B (CAT-Mn(SH)x@PMB) was immobilized on its surface through electrostatic assembly. CAT-Mn(SH)x@PMB demonstrates the ability for slow and sustained release of hydrogen sulfide (H2S). Finally, CAT-Mn(SH)x@PMB loaded microneedles (MNs) substrate were synthesized using polyvinyl alcohol (PVA) and hydroxyethyl methacrylate (HEMA), and named CAT-(MnSH)x@PMB-MNs. It exhibited enhanced enzyme and antioxidant activities, along with effective antibacterial properties. Validation findings indicate that it can up-regulate the level of M2 macrophages and reduce the level of pro-inflammatory cytokine tumor necrosis factor-α (TNF-α). Additionally, it promotes angiogenesis and rapid nerve regeneration, thereby facilitating wound healing through its dual anti-inflammatory and antibacterial effects. Hence,this study introduces a time-space tissue-penetrating and soluble microneedle patch with dual anti-inflammatory and antibacterial effects for the treatment of diabetic wounds.

Glucose Oxidase Energized Osmium with Dual-Active Centers and Triple Enzyme Activities for Infected Diabetic Wound Management.

Diabetic wounds are susceptible to bacterial infections, largely linked to high blood glucose levels (hyperglycemia). To treat such wounds, enzymes like glucose oxidase (GOx) can be combined with nanozymes (nanomaterials mimic enzymes) to use glucose effectively for purposes. However, there is still room for improvement in these systems, particularly in terms of process simplification, enzyme activity regulation, and treatment effects. Herein, the approach utilizes GOx to directly facilitate the biomineralized growth of osmium (Os) nanozyme (GOx-OsNCs), leading to dual-active centers and remarkable triple enzyme activities. Initially, GOx-OsNCs use vicinal dual-active centers, enabling a self-cascaded mechanism that significantly enhances glucose sensing performance compared to step-by-step reactions, surpassing the capabilities of other metal sources such as gold and platinum. In addition, GOx-OsNCs are integrated into a glucose-sensing gel, enabling instantaneous visual feedback. In the treatment of infected diabetic wounds, GOx-OsNCs exhibit multifaceted benefits by lowering blood glucose levels and exhibiting antibacterial properties through the generation of hydroxyl free radicals, thereby expediting healing by fostering a favorable microenvironment. Furthermore, the catalase-like activity of GOx-OsNCs aids in reducing oxidative stress, inflammation, and hypoxia, culminating in improved healing outcomes. Overall, this synergistic enzyme-nanozyme blend is user-friendly and holds considerable promise for diverse applications.

pH-Activatable Pre-Nanozyme Mediated H2S Delivery for Endo-Exogenous Regulation of Oxidative Stress in Acute Kidney Injury.

Oxidative stress induced by excess reactive oxygen species (ROS) is a primary pathogenic cause of acute kidney injury (AKI). Development of an effective antioxidation system to mitigate oxidative stress for alleviating AKI remains to be investigated. This study presents the synthesis of an ultra-small Platinum (Pt) sulfur cluster (Pt5.65S), which functions as a pH-activatable prefabricated nanozyme (pre-nanozyme). This pre-nanozyme releases hydrogen sulfide (H2S) and transforms into a nanozyme (Ptzyme) that mimics various antioxidant enzymes, including superoxide dismutase and catalase, within the inflammatory microenvironment. Notably, the Pt5.65S pre-nanozyme exhibits an endo-exogenous synergy-enhanced antioxidant therapeutic mechanism. The Ptzyme reduces oxidative damage and inflammation, while the released H2S gas promotes proneurogenesis by activating Nrf2 and upregulating the expression of antioxidant molecules and enzymes. Consequently, the Pt5.65S pre-nanozyme shows cytoprotective effects against ROS/reactive nitrogen species (RNS)-mediated damage at remarkably low doses, significantly improving treatment efficacy in mouse models of kidney ischemia-reperfusion injury and cisplatin-induced AKI. Based on these findings, the H2S-generating pre-nanozyme may represent a promising therapeutic strategy for mitigating inflammatory diseases such as AKI and others.

Ultrasmall metal alloy nanozymes mimicking neutrophil enzymatic cascades for tumor catalytic therapy.

Developing strategies that emulate the killing mechanism of neutrophils, which involves the enzymatic cascade of superoxide dismutase (SOD) and myeloperoxidase (MPO), shows potential as a viable approach for cancer therapy. Nonetheless, utilizing natural enzymes as therapeutics is hindered by various challenges. While nanozymes have emerged for cancer treatment, developing SOD-MPO cascade in one nanozyme remains a challenge. Here, we develop nanozymes possessing both SOD- and MPO-like activities through alloying Au and Pd, which exhibits the highest cascade activity when the ratio of Au and Pd is 1:3, attributing to the high d-band center and adsorption energy for superoxide anions, as determined through theoretical calculations. The Au1Pd3 alloy nanozymes exhibit excellent tumor therapeutic performance and safety in female tumor-bearing mice, with safety attributed to their tumor-specific killing ability and renal clearance ability caused by ultrasmall size. Together, this work develops ultrasmall AuPd alloy nanozymes that mimic neutrophil enzymatic cascades for catalytic treatment of tumors.

Exploring the Specificity of Nanozymes.

Nanozymes, nanomaterials exhibiting enzyme-like activities, have emerged as a prominent interdisciplinary field over the past decade. To date, over 1200 different nanomaterials have been identified as nanozymes, covering four catalytic categories: oxidoreductases, hydrolases, isomerases, and lyases. Catalytic activity and specificity are two pivotal benchmarks for evaluating enzymatic performance. Despite substantial progress being made in quantifying and optimizing the catalytic activity of nanozymes, there is still a lack of in-depth research on the catalytic specificity of nanozymes, preventing the formation of consensual knowledge and impeding a more refined and systematic classification of nanozymes. Recently, debates have emerged regarding whether nanozymes could possess catalytic specificity similar to that of enzymes. This Perspective discusses the specificity of nanozymes by referring to the catalytic specificity of enzymes, highlights the specificity gap between nanozymes and enzymes, and concludes by offering our perspective on future research on the specificity of nanozymes.

A natural biogenic nanozyme for scavenging superoxide radicals.

Biominerals, the inorganic minerals of organisms, are known mainly for their physical property-related functions in modern living organisms. Our recent discovery of the enzyme-like activities of nanomaterials, coined as nanozyme, inspires the hypothesis that nano-biominerals might function as enzyme-like catalyzers in cells. Here we report that the iron cores of biogenic ferritins act as natural nanozymes to scavenge superoxide radicals. Through analyzing eighteen representative ferritins from three living kingdoms, we find that the iron core of prokaryote ferritin possesses higher superoxide-diminishing activity than that of eukaryotes. Further investigation reveals that the differences in catalytic capability result from the iron/phosphate ratio changes in the iron core, which is mainly determined by the structures of ferritins. The phosphate in the iron core switches the iron core from single crystalline to amorphous iron phosphate-like structure, resulting in decreased affinity to the hydrogen proton of the ferrihydrite-like core that facilitates its reaction with superoxide in a manner different from that of ferric ions. Furthermore, overexpression of ferritins with high superoxide-diminishing activities in E. coli increases the resistance to superoxide, whereas bacterioferritin knockout or human ferritin knock-in diminishes free radical tolerance, highlighting the physiological antioxidant role of this type of nanozymes.

Tackling Esophageal Squamous Cell Carcinoma with ITFn-Pt(IV): A Novel Fusion of PD-L1 Blockade, Chemotherapy, and T-cell Activation.

PD-1/PD-L1 blockade immunotherapy has gained approval for the treatment of a diverse range of tumors; however, its efficacy is constrained by the insufficient infiltration of T lymphocytes into the tumor microenvironment, resulting in suboptimal patient responses. Here, a pioneering immunotherapy ferritin nanodrug delivery system denoted as ITFn-Pt(IV) is introduced. This system orchestrates a synergistic fusion of PD-L1 blockade, chemotherapy, and T-cell activation, aiming to augment the efficacy of tumor immunotherapy. Leveraging genetic engineering approach and temperature-regulated channel-based drug loading techniques, the architecture of this intelligent responsive system is refined. It is adept at facilitating the precise release of T-cell activating peptide Tα1 in the tumor milieu, leading to an elevation in T-cell proliferation and activation. The integration of PD-L1 nanobody KN035 ensures targeted engagement with tumor cells and mediates the intracellular delivery of the encapsulated Pt(IV) drugs, culminating in immunogenic cell death and the subsequent dendritic cell maturation. Employing esophageal squamous cell carcinoma (ESCC) as tumor model, the potent antitumor efficacy of ITFn-Pt(IV) is elucidated, underscored by augmented T-cell infiltration devoid of systemic adverse effects. These findings accentuate the potential of ITFn-Pt(IV) for ESCC treatment and its applicability to other malignancies resistant to established PD-1/PD-L1 blockade therapies.