Nanozyme: new horizons for responsive biomedical applications

Rational design of Au-Bi bimetallic nanozyme for NIR-II laser mediated multifunctional combined tumor therapy

To maximize the therapeutic effects and minimize the adverse effects of synergistic tumor therapies, a multifunctional nanozyme Au-Bi/ZIF-8@DOX@HA (ABZ@DOX@HA) was designed and synthesized through the Au and Bi bimetallic doping of ZIF-8, loading of the DOX, and modifying with hyaluronic acid (HA). The ABZ@DOX@HA nanoparticles (NPs) could simulate the enzymatic activities of glucose oxidase (GOx) and peroxidase (POD). Upon irradiated by near-infrared region (NIR-II) laser, the strong synergism of the photothermal abilities of the loaded Au and Bi nanodots accelerated the collapse of the ABZ structure at the tumor site considerably and released Au, Bi nanodots and DOX. The results in vitro and in vivo proved that ABZ@DOX@HA nanozyme could effectively exert the combined tumor therapy of starvation treatment, photothermal therapy (PTT), chemodynamic therapy (CDT) and chemotherapy. The current research provides a new strategy to address the inherent challenges of easy clearance and short blood circulation of small-sized NPs during the treatment of tumors with nanomedicine, as well as the aggregation and oxidation of inorganic nanodots.

Simple and Ultrasensitive Nanozyme-Linked Immunosorbent Assay for SARS-CoV-2 Detection on a Syringe-Driven Filtration Device

This work proposed a simple and ultrasensitive nanozyme-based immunoassay on a filtration device for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid protein (NP). Gold core porous platinum shell nanoparticles (Au@Pt NPs) were synthesized with high catalytic activity to oxidize 3,3',5,5'-tetramethylbenzidine, leading to an oblivious color change. The filtration device was designed based on the size difference of magnetic beads, filter membrane pore, and Au@Pt NPs. A simple, rapid, and consistent washing procedure can be performed with the help of a plastic syringe. This detection method could realize the quantitative detection of SARS-CoV-2 NP within 80 min for point-of-care needs. The limit of detection for the SARS-CoV-2 antigen was 0.01 ng/mL in buffer. The coefficients of variation of the assay were 1.78% for 10 ng/mL SARS-CoV-2 antigen, 2.03% for 1 ng/mL SARS-CoV-2 antigen, and 2.34% for the negative sample, respectively. The specificity of the detection platform was verified by the detection of various respiratory viruses. This simple and effective detection system was expected to promote substantial progress in the development and application of virus immunodetection technology.

Engineering a Bifunctional Smart Nanoplatform Integrating Nanozyme Activity and Self-Assembly for Kidney Cancer Diagnosis and Classification

Accurate diagnosis and classification of kidney cancer are crucial for high-quality healthcare services. However, the current diagnostic platforms remain challenges in the rapid and accurate analysis of large-scale clinical biosamples. Herein, we fabricated a bifunctional smart nanoplatform based on tannic acid-modified gold nanoflowers (TA@AuNFs), integrating nanozyme catalysis for colorimetric sensing and self-assembled nanoarray-assisted LDI-MS analysis. The TA@AuNFs presented peroxidase (POD)- and glucose oxidase-like activity owing to the abundant galloyl residues on the surface of AuNFs. Combined with the colorimetric assay, the TA@AuNF-based sensing nanoplatform was used to directly detect glucose in serum for kidney tumor diagnosis. On the other hand, TA@AuNFs could self-assemble into closely packed and homogeneous two-dimensional (2D) nanoarrays at liquid-liquid interfaces by using Fe3+ as a mediator. The self-assembled TA@AuNFs (SA-TA@AuNFs) arrays were applied to assist the LDI-MS analysis of metabolites, exhibiting high ionization efficiency and excellent MS signal reproducibility. Based on the SA-TA@AuNF array-assisted LDI-MS platform, we successfully extracted metabolic fingerprints from urine samples, achieving early-stage diagnosis of kidney tumor, subtype classification, and discrimination of benign from malignant tumors. Taken together, our developed TA@AuNF-based bifunctional smart nanoplatform showed distinguished potential in clinical disease diagnosis, point-of-care testing, and biomarker discovery.

Mechanistic Interrogation on Wound Healing and Scar Removing by the Mo4/3B2-x Nanoscaffold Revealed Regulated Amino Acid and Purine Metabolism

Wound rehabilitation is invariably time-consuming, scar formation further weakens therapeutic efficacy, and detailed mechanisms at the molecular level remain unclear. In this work, a Mo4/3B2-x nanoscaffold was fabricated and utilized for wound healing and scar removing in a mice model, while metabolomics was used to study the metabolic reprogramming of metabolome during therapy at the molecular level. The results showed that transition metal borides, called Mo4/3B2-x nanoscaffolds, could mimic superoxide dismutase and glutathione peroxidase to eliminate excess reactive oxygen species (ROS) in the wound microenvironment. During the therapeutic process, the Mo4/3B2-x nanoscaffold could facilitate the regeneration of wounds and removal of scars by regulating the biosynthesis of collagen, fibers, and blood vessels at the pathological, imaging, and molecular levels. Subsequent metabolomics study revealed that the Mo4/3B2-x nanoscaffold effectively ameliorated metabolic disorders in both wound and scar microenvironments through regulating ROS-related pathways including the amino acid metabolic process (including glycine and serine metabolism and glutamate metabolism) and the purine metabolic process. This study is anticipated to illuminate the potential clinical application of the Mo4/3B2-x nanoscaffold as an effective therapeutic agent in traumatic diseases and provide insights into the development of analytical methodology for interrogating wound healing and scar removal-related metabolic mechanisms.

Oxygen-bridged W-Pd atomic pairs enable H2O2 activation for sensitive immunoassays

Regulating the performance of peroxidase (POD)-like nanozymes is a prerequisite for achieving highly sensitive and accurate immunoassays. Inspired by natural enzyme catalysis, we design a highly active and selective nanozyme by loading atomically dispersed tungsten (W) sites on Pd metallene (W-O-Pdene) to construct an artificial three-dimensional (3D) catalytic center. The 3D asymmetric W-O-Pd atomic pairs can effectively stretch the O-O bonds in H2O2 and further promote the desorption of H2O to enhance POD-like activity. Moreover, the W-O-Pd sites with unique spatial structures demonstrate satisfactory specificity for H2O2 activation, effectively preventing the interference of dissolved oxygen. Accordingly, the highly active and specific W-O-Pdene nanozymes are utilized for sensitive and accurate prostate-specific antigen (PSA) immunoassay with a low detection limit of 1.92 pg mL-1, superior to commercial enzyme-linked immunosorbent assay.

Biotemplated Platinum Nanozymes: Synthesis, Catalytic Regulation and Biomedical Applications

Platinum (Pt) nanozymes with multiple intrinsic enzyme-mimicking activities have attracted extensive attention in biomedical fields due to their high catalytic activity, ease of modification, and convenient storage. However, the Pt nanozymes synthesized by the traditional method often suffer from uncontrollable morphology and poor stability under physicochemical conditions, resulting in unsatisfactory catalytic behavior in practical applications. To optimize the catalytic ability, biological templates have been introduced recently, which can guide the deposition of platinum ions on their surface to form specific morphologies and then stabilize the resulting Pt nanozymes. Given the promising potential of biotemplated Pt nanozymes in practical applications, it is essential to conduct a systematic and comprehensive review to summarize their recent research progress. In this review, we first categorize the biological templates and discuss the mechanisms as well as characteristics of each type of biotemplate in directing the growth of Pt nanozyme. Factors that impact the growth of biotemplated Pt nanozymes are then analyzed, followed by summarizing their biomedical applications. Finally, the challenges and opportunities in this field are outlined. This review article aims to provide theoretical guidance for developing Pt nanozymes with robust functionalities in biomedical applications.

Multi-Enzyme Mimetic MoCu Dual-Atom Nanozyme Triggering Oxidative Stress Cascade Amplification for High-Efficiency Synergistic Cancer Therapy

Single-atom nanozymes (SAzymes) with ultrahigh atom utilization efficiency have been extensively applied in reactive oxygen species (ROS)-mediated cancer therapy. However, the high energy barriers of reaction intermediates on single-atom sites and the overexpressed antioxidants in the tumor microenvironment restrict the amplification of tumor oxidative stress, resulting in unsatisfactory therapeutic efficacy. Herein, we report a multi-enzyme mimetic MoCu dual-atom nanozyme (MoCu DAzyme) with various catalytic active sites, which exhibits peroxidase, oxidase, glutathione (GSH) oxidase, and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase mimicking activities. Compared with Mo SAzyme, the introduction of Cu atoms, formation of dual-atom sites, and synergetic catalytic effects among various active sites enhance substrate adsorption and reduce the energy barrier, thereby endowing MoCu DAzyme with stronger catalytic activities. Benefiting from the above enzyme-like activities, MoCu DAzyme can not only generate multiple ROS, but also deplete GSH and block its regeneration to trigger the cascade amplification of oxidative stress. Additionally, the strong optical absorption in the near-infrared II bio-window endows MoCu DAzyme with remarkable photothermal conversion performance. Consequently, MoCu DAzyme achieves high-efficiency synergistic cancer treatment incorporating collaborative catalytic therapy and photothermal therapy. This work will advance the therapeutic applications of DAzymes and provide valuable insights for nanocatalytic cancer therapy.

Nanozyme-Enabled Biomedical Diagnosis: Advances, Trends, and Challenges

As nanoscale materials with the function of catalyzing substrates through enzymatic kinetics, nanozymes are regarded as potential alternatives to natural enzymes. Compared to protein-based enzymes, nanozymes exhibit attractive characteristics of low preparation cost, robust activity, flexible performance adjustment, and versatile functionalization. These advantages endow them with wide use from biochemical sensing and environmental remediation to medical theranostics. Especially in biomedical diagnosis, the feature of catalytic signal amplification provided by nanozymes makes them function as emerging labels for the detection of biomarkers and diseases, with rapid developments observed in recent years. To provide a comprehensive overview of recent progress made in this dynamic field, here an overview of biomedical diagnosis enabled by nanozymes is provided. This review first summarizes the synthesis of nanozyme materials and then discusses the main strategies applied to enhance their catalytic activity and specificity. Subsequently, representative utilization of nanozymes combined with biological elements in disease diagnosis is reviewed, including the detection of biomarkers related to metabolic, cardiovascular, nervous, and digestive diseases as well as cancers. Finally, some development trends in nanozyme-enabled biomedical diagnosis are highlighted, and corresponding challenges are also pointed out, aiming to inspire future efforts to further advance this promising field.

Magnetic nanoflowers: a hybrid platform for enzyme immobilization

The use of organic-inorganic hybrid nanoflowers as a support material for enzyme immobilization has gained significant attention in recent years due to their high stability, ease of preparation, and enhanced catalytic activity. However, a major challenge in utilizing these hybrid nanoflowers for enzyme immobilization is the difficulty in handling and separating them due to their low density and high dispersion. To address this issue, magnetic nanoflowers have emerged as a promising alternative enzyme immobilization platform due to their easy separation, structural stability, and ability to enhance catalytic efficiency. This review focuses on different methods for designing magnetic nanoflowers, as well as future research directions. Additionally, it provides examples of enzymes immobilized in the form of magnetic nanoflowers and their applications in environmental remediation, biosensors, and food industries. Finally, the review discusses possible ways to improve the material for enhanced catalytic activity, structural stability, and scalability.

Spatially Decoupled H2O2 Activation Pathways and Multi-Enzyme Activities in Rod-Shaped CeO2 with Implications for Facet Distribution

CeO2, particularly in the shape of rod, has recently gained considerable attention for its ability to mimic peroxidase (POD) and haloperoxidase (HPO). However, this multi-enzyme activities unavoidably compete for H2O2 affecting its performance in relevant applications. The lack of consensus on facet distribution in rod-shaped CeO2 further complicates the establishment of structure-activity correlations, presenting challenges for progress in the field. In this study, the HPO-like activity of rod-shaped CeO2 is successfully enhanced while maintaining its POD-like activity through a facile post-calcination method. By studying the spatial distribution of these two activities and their exclusive H2O2 activation pathways on CeO2 surfaces, this study finds that the increased HPO-like activity originated from the newly exposed (111) surface at the tip of the shortened rods after calcination, while the unchanged POD-like activity is attributed to the retained (110) surface in their lateral area. These findings not only address facet distribution discrepancies commonly reported in the literature for rod-shaped CeO2 but also offer a simple approach to enhance its antibacterial performance. This work is expected to provide atomic insights into catalytic correlations and guide the design of nanozymes with improved activity and reaction specificity.

Ancient wisdom and modern innovations: Methods of administering healing

This issue of the Biomedical Journal highlights major advancements in drug delivery, including aptamer-functionalized liposomes and nanozymes. A new biomarker combination shows promise for improved diagnosis of idiopathic pulmonary fibrosis. Mesenchymal stem cells are suggested to mitigate inflammation in systemic lupus erythematosus, and a potential positive feedback loop driven by a prevalent mRNA modification is suggested to enhance NSCLC progression. Additional articles explore a pathological impact on autophagy leading to muscle dysfunction, the benefits of integrating an orphan drug with standard therapy for glioblastoma patients, and the influence of transcriptional super-enhancers in early-stage esophageal squamous cell carcinoma. Finally, this issue provides insights into the roles of different Blastocystis subtypes, and the use of laser light for treating infantile hemangioma.

Multifunctional nanozymes for disease diagnosis and therapy

The development of nanotechnology has brought about groundbreaking advancements in diseases' diagnostics and therapeutics. Among them, multifunctional nanomaterials with enzyme-like activities (i.e., nanozymes) featured with high stability, large surface area for bioconjugation, and easy storage, offer unprecedented opportunities for disease diagnostics and treatment. Recent years have witnessed the great progress of nanozyme-based theranostics. To highlight these achievements, this review first introduces the recent advancements on nanozymes in biosensing and diagnostics. Then, it summarizes the applications of nanozymes in therapeutics including anti-tumor and antibacterial treatment, anti-inflammatory treatment, and other diseases treatment. In addition, several targeted strategies to improve the therapeutic efficacy of nanozyme are discussed. Finally, the opportunities and challenges in the field of diagnosis and therapy are summarized.

The potential use of nanozyme in aging and age-related diseases

The effects of an increasingly elderly population are among the most far-reaching in 21st-century society. The growing healthcare expense is mainly attributable to the increased incidence of chronic illnesses that accompany longer life expectancies. Different ideas have been put up to explain aging, but it is widely accepted that oxidative damage to proteins, lipids, and nucleic acids contributes to the aging process. Increases in life expectancy in all contemporary industrialized cultures are accompanied by sharp increases in the prevalence of age-related diseases such as cardiovascular and neurological conditions, type 2 diabetes, osteoporosis, and cancer. Therefore, academic and public health authorities should prioritize the development of therapies to increase health span. Nanozyme (NZ)-like activity in nanomaterials has been identified as promising anti-aging nanomedicines. More than that, nanomaterials displaying catalytic activities have evolved as artificial enzymes with high structural stability, variable catalytic activity, and functional diversity for use in a wide range of biological settings, including those dealing with age-related disorders. Due to their inherent enzyme-mimicking qualities, enzymes have attracted significant interest in treating diseases associated with reactive oxygen species (ROS). The effects of NZs on aging and age-related disorders are summarized in this article. Finally, prospects and threats to enzyme research and use in aging and age-related disorders are offered.

Single-site iron-anchored amyloid hydrogels as catalytic platforms for alcohol detoxification

Constructing effective antidotes to reduce global health impacts induced by alcohol prevalence is a challenging topic. Despite the positive effects observed with intravenous applications of natural enzyme complexes, their insufficient activities and complicated usage often result in the accumulation of toxic acetaldehyde, which raises important clinical concerns, highlighting the pressing need for stable oral strategies. Here we present an effective solution for alcohol detoxification by employing a biomimetic-nanozyme amyloid hydrogel as an orally administered catalytic platform. We exploit amyloid fibrils derived from β-lactoglobulin, a readily accessible milk protein that is rich in coordinable nitrogen atoms, as a nanocarrier to stabilize atomically dispersed iron (ferrous-dominated). By emulating the coordination structure of the horseradish peroxidase enzyme, the single-site iron nanozyme demonstrates the capability to selectively catalyse alcohol oxidation into acetic acid, as opposed to the more toxic acetaldehyde. Administering the gelatinous nanozyme to mice suffering from alcohol intoxication significantly reduced their blood-alcohol levels (decreased by 55.8% 300 min post-alcohol intake) without causing additional acetaldehyde build-up. Our hydrogel further demonstrates a protective effect on the liver, while simultaneously mitigating intestinal damage and dysbiosis associated with chronic alcohol consumption, introducing a promising strategy in effective alcohol detoxification.

Cutting-Edge Biomaterials in Intervertebral Disc Degeneration Tissue Engineering

Intervertebral disc degeneration (IVDD) stands as the foremost contributor to low back pain (LBP), imposing a substantial weight on the world economy. Traditional treatment modalities encompass both conservative approaches and surgical interventions; however, the former falls short in halting IVDD progression, while the latter carries inherent risks. Hence, the quest for an efficacious method to reverse IVDD onset is paramount. Biomaterial delivery systems, exemplified by hydrogels, microspheres, and microneedles, renowned for their exceptional biocompatibility, biodegradability, biological efficacy, and mechanical attributes, have found widespread application in bone, cartilage, and various tissue engineering endeavors. Consequently, IVD tissue engineering has emerged as a burgeoning field of interest. This paper succinctly introduces the intervertebral disc (IVD) structure and the pathophysiology of IVDD, meticulously classifies biomaterials for IVD repair, and reviews recent advances in the field. Particularly, the strengths and weaknesses of biomaterials in IVD tissue engineering are emphasized, and potential avenues for future research are suggested.

Stimuli-responsive polymer-based nanosystems for cardiovascular disease theranostics

Stimulus-responsive polymers have found widespread use in biomedicine due to their ability to alter their own structure in response to various stimuli, including internal factors such as pH, reactive oxygen species (ROS), and enzymes, as well as external factors like light. In the context of atherosclerotic cardiovascular diseases (CVDs), stimulus-response polymers have been extensively employed for the preparation of smart nanocarriers that can deliver therapeutic and diagnostic drugs specifically to inflammatory lesions. Compared with traditional drug delivery systems, stimulus-responsive nanosystems offer higher sensitivity, greater versatility, wider applicability, and enhanced biosafety. Recent research has made significant contributions towards designing stimulus-responsive polymer nanosystems for CVDs diagnosis and treatment. This review summarizes recent advances in this field by classifying stimulus-responsive polymer nanocarriers according to different responsiveness types and describing numerous stimuli relevant to these materials. Additionally, we discuss various applications of stimulus-responsive polymer nanomaterials in CVDs theranostics. We hope that this review will provide valuable insights into optimizing the design of stimulus-response polymers for accelerating their clinical application in diagnosing and treating CVDs.

Fe/Cu MOFs of Fe2+-rich and Cu-doping via in situ reduction as nanozyme for peroxidase-like catalycity enhancement

Fe-MOFs of mixed valence was synthesized by a solvothermal method via the in-situ reduction of ethylene glycol (EG) pre-coordination with the proper ratio of Fe2+/Fe3+ between 0.83 and 2.46. Synchronously with copper introduction, the Fe/Cu MOFs of mixed valence (Fe/Cu-MVMOFs) was then one pot acquired to remarkably improve the affinity of Fe2+ and Cu+ to H2O2 and promote the conversion efficiency of Fe2+/Fe3+ via the electron transfer among Fe-Cu bimetal clusters (XPS and XRD). Hence, the maximum reaction rate of H2O2 with Fe/Cu-MVMOFs reached 16.65 M·s-1, along with Km as low as 0.0479 mM. H2O2 and glutathione (GSH) were efficiently detected, ranging from 0.25 to 60 µM and from 0.2 to 40 µM, respectively. The investigation of catalyzation selectivity and practical serum detection by Fe/Cu-MVMOFs illustrated the efficacy and efficiency, denoting Fe/Cu-MVMOFs as the promising peroxidase candidate.

Enhancing radiation-resistance and peroxidase-like activity of single-atom copper nanozyme via local coordination manipulation

The inactivation of natural enzymes by radiation poses a great challenge to their applications for radiotherapy. Single-atom nanozymes (SAzymes) with high structural stability under such extreme conditions become a promising candidate for replacing natural enzymes to shrink tumors. Here, we report a CuN3-centered SAzyme (CuN3-SAzyme) that exhibits higher peroxidase-like catalytic activity than a CuN4-centered counterpart, by locally regulating the coordination environment of single copper sites. Density functional theory calculations reveal that the CuN3 active moiety confers optimal H2O2 adsorption and dissociation properties, thus contributing to high enzymatic activity of CuN3-SAzyme. The introduction of X-ray can improve the kinetics of the decomposition of H2O2 by CuN3-SAzyme. Moreover, CuN3-SAzyme is very stable after a total radiation dose of 500 Gy, without significant changes in its geometrical structure or coordination environment, and simultaneously still retains comparable peroxidase-like activity relative to natural enzymes. Finally, this developed CuN3-SAzyme with remarkable radioresistance can be used as an external field-improved therapeutics for enhancing radio-enzymatic therapy in vitro and in vivo. Overall, this study provides a paradigm for developing SAzymes with improved enzymatic activity through local coordination manipulation and high radioresistance over natural enzymes, for example, as sensitizers for cancer therapy.

Cerium Vanadate Nanozyme with pH-Dependent Dual Enzymatic Activity for Glioblastoma Targeted Therapy and Postradiotherapy Damage Protection

Nanocatalytic therapy is an emerging technology that uses synthetic nanoscale enzyme mimics for biomedical treatment. However, in the field of neuroscience, achieving neurological protection while simultaneously killing tumor cells is a technical challenge. Herein, we synthesized a biomimic and translational cerium vanadate (CeVO4) nanozyme for glioblastoma (GBM) therapy and the repair of brain damage after GBM ionizing radiation (IR). This system exhibited pH dependence: it showed potent Superoxide dismutase (SOD) enzyme activity in a neutral environment and Peroxidase (POD) enzyme activity in an acidic environment. In GBM cells, this system acted in lysosomes, causing cellular damage and reactive oxygen species (ROS) accumulation; in neuronal cells, this nanozyme could undergo lysosomal escape and nanozyme aggregation with mitochondria, reversing the mitochondrial damage caused by IR and restoring the expression level of the antiapoptotic BCL-2 protein. Mechanistically, we believe that this distribution difference is related to the specific uptake internalization mechanism and lysosomal repair pathway in neurons, and ultimately led to the dual effect of tumor killing and nerve repair in the in vivo model. In summary, this study provides insight into the repair of brain damage after GBM radiation therapy.

Two decades of ceria nanoparticle research: structure, properties and emerging applications

Cerium oxide nanoparticles (CeNPs) are versatile materials with unique and unusual properties that vary depending on their surface chemistry, size, shape, coating, oxidation states, crystallinity, dopant, and structural and surface defects. This review encompasses advances made over the past twenty years in the development of CeNPs and ceria-based nanostructures, the structural determinants affecting their activity, and translation of these distinct features into applications. The two oxidation states of nanosized CeNPs (Ce3+/Ce4+) coexisting at the nanoscale level facilitate the formation of oxygen vacancies and defect states, which confer extremely high reactivity and oxygen buffering capacity and the ability to act as catalysts for oxidation and reduction reactions. However, the method of synthesis, surface functionalization, surface coating and defects are important factors in determining their properties. This review highlights key properties of CeNPs, their synthesis, interactions, and reaction pathways and provides examples of emerging applications. Due to their unique properties, CeNPs have become quintessential candidates for catalysis, chemical mechanical planarization (CMP), sensing, biomedical applications, and environmental remediation, with tremendous potential to create novel products and translational innovations in a wide range of industries. This review highlights the timely relevance and the transformative potential of these materials in addressing societal challenges and driving technological advancements across these fields.

Perovskite hydroxide-based laccase mimics with controllable activity for environmental remediation and biosensing

Constructing relatively inexpensive nanomaterials to simulate the catalytic performance of laccase is of great significance in recent years. Although research on improving laccase-like activity by regulating ligands of copper (amino acids or small organic molecules, etc.) have achieved remarkable success. There are few reports on improving laccase-like activity by adjusting the composition of metal Cu. Here, we used perovskite hydroxide AB(OH)6 as a model to evaluate the relationship between Cu based alloys and their laccase-like activity. We found that when the Cu/Mn alloy ratio of the perovskite hydroxide A point is greater than 1, the laccase-like activity of the binary alloy perovskite hydroxide is higher than that of the corresponding single Cu. Based on the measurements of XPS and ICP-MS, we deduced that the improvements of laccase-like activity mainly attribute to the ratio of Cu+/Cu2+and the content of Cu. Moreover, two types of substrates (toxic pollutants and catechol neurotransmitters) were used to successfully demonstrated such nanozymes' excellent environmental protecting function and biosensing property. This work will provide a novel approach for the construction and application of laccase-like nanozymes in the future.

Glucose-based biofuel cells and their applications in medical implants: A review

In glucose biofuel cells (G-BFCs), glucose oxidation at the anode and oxygen reduction at the cathode yield electrons, which generate electric energy that can power a wide range of electronic devices. Research associated with the development of G-BFCs has increased in popularity among researchers because of the eco-friendly nature of G-BFCs (as related to their construction) and their evolution from inexpensive bio-based materials. In addition, their excellent specificity towards glucose as an energy source, and other properties, such as small size and weight, make them attractive within various demanding applied environments. For example, G-BFCs have received much attention as implanted devices, especially for uses related to cardiac activities. Envisioned pacemakers and defibrillators powered by G-BFCs would not be required to have conventional lithium batteries exchanged every 5-10 years. However, future research is needed to develop G-BFCs demonstrating more stable power consistency and improved lifespan, as well as solving the challenges in converting laboratory-made implantable G-BFCs into implanted devices in the human body. The categorization of G-BFCs as a subcategory of different biofuel cells and their performance is reviewed in this article.

Palladium/Platinum/Ruthenium Trimetallic Dendritic Nanozymes Exhibiting Enhanced Peroxidase-like Activity for Signal Amplification of Lateral Flow Immunoassays

Developing ultrasensitive lateral flow immunoassays (LFIAs) has garnered significant attention in the field of point-of-care testing. In this study, a trimetallic dendritic nanozyme (Pd@Pt-Ru) was synthesized through Ru deposition on a Pd@Pt core and utilized to enhancing the sensitivity of LFIAs. Pd@Pt-Ru exhibited a Km value of 5.23 mM for detecting H2O2, which indicates an H2O2 affinity comparable with that of horseradish peroxidase. The Ru surface layer reduces the activation energy barrier, which increases the maximum reaction rate. As a proof of concept, the proposed Pd@Pt-Ru nanozyme was incorporated into LFIAs (A-Pd@Pt-Ru-LFIAs) for detecting human chorionic gonadotropin (hCG). Compared with conventional gold nanoparticle (AuNP)-LFIAs, A-Pd@Pt-Ru-LFIAs demonstrated 250-fold increased sensitivity, thereby enabling a visible detection limit as low as 0.1 IU/L. True positive and negative rates both reached 100%, which renders the proposed Pd@Pt-Ru nanozyme suitable for detecting hCG in clinical samples.

Microfluidic synthesis of hemin@ZIF-8 nanozyme with applications in cellular reactive oxygen species detection and anticancer drug screening

Zeolitic imidazolate framework-8 (ZIF-8) encapsulating enzymatically active biomolecules has emerged as a novel biocompatible nanozyme and offers significant implications for bioanalysis of various biomarkers towards early diagnosis of severe diseases such as cancers. However, the rapid, continuous and scalable synthesis of these nanozymes still remains challenging. In this work, we proposed a novel microfluidic approach for rapid and continuous synthesis of hemin@ZIF-8 nanozyme. By employing a distinctive combination of zigzag-shaped channel and spiral channel with sudden expansion structures, we have enhanced the mixing efficiency within the chip and achieved effective encapsulation of hemin in ZIF-8. The resulting hemin@ZIF-8 nanoparticles exhibit peroxidase-like activity and are capable of detecting free H2O2 with a limit of detection (LOD) as low as 45 nM, as well as H2O2 secreted by viable cells with a detection threshold of approximately 10 cells per mL. By leveraging this method, we achieved successful detection of cancer cells and effective screening of anticancer drugs that induce oxidative stress injury in cancer cells. This innovative microfluidic strategy offers a new avenue for synthesizing functional nanocomposites to facilitate the development of next-generation diagnostic tools for early disease detection and personalized medicine.

Structural engineering of Pt-on-Rh hollow nanorods with high-performance peroxidase-like specific activity for colorimetric detection

The preparation of nanozymes with high specific activity is highly important for various applications. However, only a few nanozymes have specific activities comparable to natural enzymes. Herein, novel Pt-on-Rh hollow nanorods (PtRh HNRs) were developed, in which surface Pt exhibited adjustable dispersity and interior Rh served as the support. The optimized PtRh HNRs demonstrated high-performance peroxidase (POD)-like activity, with a specific activity as high as 1352 U mg-1, which was 3.86 times that of their monometallic Pt counterparts. Density functional theory (DFT) calculations illustrated that the presence of Rh decreased the energy barrier of the rate-determining step. When PtRh HNRs were used as nanozymes in the colorimetric detection of hydrogen peroxide (H2O2) and ascorbic acid (AA), the limits of detection (LODs) were as low as 9.97 μM and 0.039 μM, respectively. The current work highlights a facile and powerful strategy for manufacturing nanozymes with high specific activity and demonstrates that the prepared PtRh HNRs have the potential for analysis and determination.

Metal-ligand dual-site single-atom nanozyme mimicking urate oxidase with high substrates specificity

In nature, coenzyme-independent oxidases have evolved in selective catalysis using isolated substrate-binding pockets. Single-atom nanozymes (SAzymes), an emerging type of non-protein artificial enzymes, are promising to simulate enzyme active centers, but owing to the lack of recognition sites, realizing substrate specificity is a formidable task. Here we report a metal-ligand dual-site SAzyme (Ni-DAB) that exhibited selectivity in uric acid (UA) oxidation. Ni-DAB mimics the dual-site catalytic mechanism of urate oxidase, in which the Ni metal center and the C atom in the ligand serve as the specific UA and O2 binding sites, respectively, characterized by synchrotron soft X-ray absorption spectroscopy, in situ near ambient pressure X-ray photoelectron spectroscopy, and isotope labeling. The theoretical calculations reveal the high catalytic specificity is derived from not only the delicate interaction between UA and the Ni center but also the complementary oxygen reduction at the beta C site in the ligand. As a potential application, a Ni-DAB-based biofuel cell using human urine is constructed. This work unlocks an approach of enzyme-like isolated dual sites in boosting the selectivity of non-protein artificial enzymes.

Nanozymes: Potential Therapies for Reactive Oxygen Species Overproduction and Inflammation in Ischemic Stroke and Traumatic Brain Injury

Nanozymes, which can selectively scavenge reactive oxygen species (ROS), have recently emerged as promising candidates for treating ischemic stroke and traumatic brain injury (TBI) in preclinical models. ROS overproduction during the early phase of these diseases leads to oxidative brain damage, which has been a major cause of mortality worldwide. However, the clinical application of ROS-scavenging enzymes is limited by their short in vivo half-life and inability to cross the blood-brain barrier. Nanozymes, which mimic the catalytic function of natural enzymes, have several advantages, including cost-effectiveness, high stability, and easy storage. These advantages render them superior to natural enzymes for disease diagnosis and therapeutic interventions. This review highlights recent advancements in nanozyme applications for ischemic stroke and TBI, emphasizing their potential to mitigate the detrimental effect of ROS overproduction, oxidative brain damage, inflammation, and blood-brain barrier compromise. Therefore, nanozymes represent a promising treatment modality for ROS overproduction conditions in future medical practices.

Nanoproteases: Alternatives to Natural Protease for Biotechnological Applications

Some nanomaterials with intrinsic protease-like activity have the advantages of good stability, biosafety, low price, large-scale preparation and unique property of nanomaterials, which are promising alternatives for natural proteases in various applications. An especial term, "nanoprotease", has been coined to stress the intrinsic proteolytic property of these nanomaterials. As a new generation of artificial proteases, they have become a burgeoning field, attracting many researchers to design and synthesize high performance nanoproteases. In this review, we summarize recent progress on all types of nanoproteases with regard of their activity, mechanism and application and introduce a new and effective strategy for engineering high-performance nanoproteases. In addition, we discuss the challenges and opportunities of nanoprotease research in the future.

Al2O3-Stabilized Pt Nanozymes: Peroxidase Mimetics and Application in Glucose Detection

As promising alternatives for natural enzymes, much attention has been paid to nanozymes. And our recent study showed that the medium acid sites on the support are the active sites for the adsorption and oxidation of the substrate. Thus, in this work, due to the abundance of medium acid sites, Al2O3 was chosen as the support to prepare Pt/Al2O3 nanozymes. Through the Pt/Al2O3 samples, we further proved that the distribution of the Pt clusters and the amount of the medium acid sites can significantly influence the peroxidase-like activity. Then the Pt/Al2O3 sample was used for the detection of glucose. And as low as 0.96 μM glucose could be detected with a linear range from 5-60 μM via our method. This work showed the great potential applications of the easily prepared Pt/Al2O3 samples in varieties of simple, robust, and easy-to-make analytical approaches in the future.

Nanozymes for biomedical applications: Multi-metallic systems may improve activity but at the cost of higher toxicity?

Nanozymes are nanomaterials with intrinsic enzyme-like activity with selected advantages over native enzymes such as simple synthesis, controllable activity, high stability, and low cost. These materials have been explored as surrogates to natural enzymes in biosensing, therapeutics, environmental protection, and many other fields. Among different nanozymes classes, metal- and metal oxide-based nanozymes are the most widely studied. In recent years, bi- and tri-metallic nanomaterials have emerged often showing improved nanozyme activity, some of which even possess multifunctional enzyme-like activity. Taking this concept even further, high-entropy nanomaterials, that is, complex multicomponent alloys and ceramics like oxides, may potentially enhance activity even further. However, the addition of various elements to increase catalytic activity may come at the cost of increased toxicity. Since many nanozyme compositions are currently being explored for in vivo biomedical applications, such as cancer therapeutics, toxicity considerations in relation to nanozyme application in biomedicine are of vital importance for translation. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials Diagnostic Tools > Diagnostic Nanodevices.

Challenges of enzyme therapy: Why two players are better than one

Enzyme-based therapy has garnered significant attention for its current applications in various diseases. Despite the notable advantages associated with the use of enzymes as therapeutic agents, that could have high selectivity, affinity, and specificity for the target, their application faces challenges linked to physico-chemical and pharmacological properties. These limitations can be addressed through the encapsulation of enzymes in nanoplatforms as a comprehensive solution to mitigate their degradation, loss of activity, off-target accumulation, and immunogenicity, thus enhancing bioavailability, therapeutic efficacy, and circulation time, thereby reducing the number of administrations, and ameliorating patient compliance. The exploration of novel nanomedicine-based enzyme therapeutics for the treatment of challenging diseases stands as a paramount goal in the contemporary scientific landscape, but even then it is often not enough. Combining an enzyme with another therapeutic (e.g., a small molecule, another enzyme or protein, a monoclonal antibody, or a nucleic acid) within a single nanocarrier provides innovative multidrug-integrated therapy and ensures that both the actives arrive at the target site and exert their therapeutic effect, leading to synergistic action and superior therapeutic efficacy. Moreover, this strategic approach could be extended to gene therapy, a field that nowadays has gained increasing attention, as enzymes acting at genomic level and nucleic acids may be combined for synergistic therapy. This multicomponent therapeutic approach opens opportunities for promising future developments. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Neurological Disease Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Rapid Selenoprotein Activation by Selenium Nanoparticles to Suppresses Osteoclastogenesis and Pathological Bone Loss

Osteoclast hyperactivation stands as a significant pathological factor contributing to the emergence of bone disorders driven by heightened oxidative stress levels. The modulation of the redox balance to scavenge reactive oxygen species emerges as a viable approach to addressing this concern. Selenoproteins, characterized by selenocysteine (SeCys2) as the active center, are crucial for selenium-based antioxidative stress therapy for inflammatory diseases. This study reveals that surface-active elemental selenium (Se) nanoparticles, particularly lentinan-Se (LNT-Se), exhibit enhanced cellular accumulation and accelerated metabolism to SeCys2, the primary active Se form in biological systems. Consequently, LNT-Se demonstrates significant inhibition of osteoclastogenesis. Furthermore, in vivo studies underscore the superior therapeutic efficacy of LNT-Se over SeCys2, potentially attributable to the enhanced stability and safety profile of LNT-Se. Specifically, LNT-Se effectively modulates the expression of the selenoprotein GPx1, thereby exerting regulatory control over osteoclastogenesis inhibition, and the prevention of osteolysis. In summary, these results suggest that the prompt activation of selenoproteins by Se nanoparticles serves to suppress osteoclastogenesis and pathological bone loss by upregulating GPx1. Moreover, the utilization of bioactive Se species presents a promising avenue for effectively managing bone disorders.

Oxygen-Vacancy-Rich Monolayer BiO2- X Nanosheets for Bacterial Sepsis Management via Dual Physically Antibacterial and Chemically Anti-inflammatory Functions

Sepsis is defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection. Effective treatment of bacterial sepsis remains challenging due to the rapid progression of infection and the systemic inflammatory response. In this study, monolayer BiO2- X nanosheets (BiO2- X NSs) with oxygen-rich vacancies through sonication-assisted liquid-phase exfoliation are successfully synthesized. Herein, the BiO2- X NSs exhibit a novel nanozyme-enabled intervention strategy for the management of bacterial sepsis, based on its pH dependent dual antibacterial and anti-inflammatory functions. BiO2- X NSs exhibit effective antibacterial by utilizing oxidase (OXD)-like activity. Additionally, BiO2- X NSs can scavenge multiple reactive oxygen species (ROS) and mitigate systemic hyperinflammation by mimicking superoxide dismutase (SOD) and catalase (CAT). These dual capabilities of BiO2- X NSs allow them to address bacterial infection, proinflammatory cytokines secretion and ROS burst collaboratively, effectively reversing the progression of bacterial sepsis. In vivo experiments have demonstrated that BiO2- X NSs significantly reduce bacterial burden, attenuate systemic hyperinflammation, and rapidly rescued organ damage. Importantly, no obvious adverse effects are observed at the administered dose of BiO2- X NSs. This study presents a novel defect engineering strategy for the rational design of high-performance nanozymes and development of new nanomedicines for managing bacterial sepsis.

A spatial-potential resolved bipolar electrode electrochemiluminescence biosensor based on polarity conversion for dual-mode detection of miRNA-122 and CEA

In this work, a spatial-potential resolved bipolar electrode electrochemiluminescence (BPE-ECL) biosensor based on polarity conversion strategy and CuHCF electrocatalyst was constructed for dual-mode detection of miRNA-122 and carcinoembryonic antigen (CEA). ECL technology was firstly used to systematically study the polarity conversion of BPE. It was found that changing the polarity of the driving voltage would cause the polarity change of BPE, and led to the change of the luminescent position of Ru(bpy)32+. As a "proof-of-concept application", we developed a shielded dual-channel BPE-ECL biosensor for dual-mode detection of miRNA-122 and CEA. In order to further improve the detection sensitivity, a non-precious metal electrocatalyst CuHCF with outstanding electrocatalytic reduction activity of H2O2 was firstly introduced to the BPE-ECL biosensor for signal amplification, which could generate high faradaic current under the excitation of negative potential. Based on the charge neutrality principle of BPE, the enhancement of the faradaic current resulted in the ECL signal amplification of Ru(bpy)32+. The targets in the sensing grooves caused the introduction or fall off of CuHCF, which led to the ECL signal change of Ru(bpy)32+ in the signal grooves, and realized the dual-mode detection of miRNA-122 and CEA. This work provided a deeper understanding of the polarity change of BPE. Furthermore, the introduction of non-precious metal electrocatalyst had broadened the application range of BPE-ECL sensors.

Iridium nanoparticles supported on polyaniline nanotubes for peroxidase mimicking towards total antioxidant capacity assay of fruits and vegetables

In this study, a straightforward approach is presented for the first time to anchor Ir nanoparticles on the surface of uniform polyaniline (PANi) nanotubes (NTs), which can be used as an efficient peroxidase (POD)-like catalyst. The morphology and chemical structure of the PANi-Ir nanocomposite are characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffractometer (XRD), Raman and X-ray photoelectron spectroscopy (XPS) measurements. Owing to the strong interaction between Ir nanoparticles and PANi, a remarkable catalytic enhancement is achieved compared to the bare Ir black catalyst and individual PANi NTs, dominating withan electron transfer mechanism. Furthermore, an efficient colorimetric sensor for ascorbic acid (AA) is developed with a low detection limit of 1.0 μM (S/N = 3), and a total antioxidant capacity (TAC) sensing platform is also constructed for the rigorous detection and analysis of fruits and vegetables.

Progress in the Computer-Aided Analysis in Multiple Aspects of Nanocatalysis Research

Making the utmost of the differences and advantages of multiple disciplines, interdisciplinary integration breaks the science boundaries and accelerates the progress in mutual quests. As an organic connection of material science, enzymology, and biomedicine, nanozyme-related research is further supported by computer technology, which injects in new vitality, and contributes to in-depth understanding, unprecedented insights, and broadened application possibilities. Utilizing computer-aided first-principles method, high-speed and high-throughput mathematic, physic, and chemic models are introduced to perform atomic-level kinetic analysis for nanocatalytic reaction process, and theoretically illustrate the underlying nanozymetic mechanism and structure-function relationship. On this basis, nanozymes with desirable properties can be designed and demand-oriented synthesized without repeated trial-and-error experiments. Besides that, computational analysis and device also play an indispensable role in nanozyme-based detecting methods to realize automatic readouts with improved accuracy and reproducibility. Here, this work focuses on the crossing of nanocatalysis research and computational technology, to inspire the research in computer-aided analysis in nanozyme field to a greater extent.

Deciphering the Catalytic Mechanism of Peroxidase-like Activity of Iron Sulfide Nanozymes

Iron sulfide nanomaterials represented by FeS2 and Fe3S4 nanozymes have attracted increasing attention due to their biocompatibility and peroxidase-like (POD-like) catalytic activity in disease diagnosis and treatments. However, the mechanism responsible for their POD-like activities remains unclear. Herein, taking the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) by H2O2 on FeS2(100) and Fe3S4(001) surfaces, the catalytic mechanism was investigated in detail using density functional theory (DFT) calculations and experimental characterizations. Our experimental results showed that the catalytic activity of FeS2 nanozymes was significantly higher than that of Fe3S4 nanozymes. Our DFT calculations indicated that the surface iron ions of iron sulfide nanozymes could effectively catalyze the production of HO• radicals via the interactions between Fe 3d electrons and the frontier orbitals of H2O2 in the range of -10 to 5 eV. However, FeS2 nanozymes exhibited higher POD-like activity due to the surface Fe(II) binding to H2O2, forming inner-orbital complexes, which results in a larger binding energy and a smaller energy barrier for the base-like decomposition of H2O2. In contrast, the surface iron ions of Fe3S4 nanozymes bind to H2O2, forming outer-orbital complexes, which results in a smaller binding energy and a larger energy barrier for the base-like decomposition of H2O2. The charge transfer analysis showed that FeS2 nanozymes transferred 0.12 e and Fe3S4 nanozymes transferred 0.05 e from their surface iron ions to H2O2, respectively. The simulations were consistent with the experimental observations that the FeS2 nanozymes had a greater affinity for H2O2 compared to that of Fe3S4 nanozymes. This work provides a theoretical foundation for the rational design and accurate preparation of iron sulfide functional nanozymes.

Immobilized Multi-Enzyme/Nanozyme Biomimetic Cascade Catalysis for Biosensing Applications

Multiple enzyme-induced cascade catalysis has an indispensable role in the process of complex life activities, and is widely used to construct robust biosensors for analyzing various targets. The immobilized multi-enzyme cascade catalysis system is a novel biomimetic catalysis strategy that immobilizes various enzymes with different functions in stable carriers to simulate the synergistic catalysis of multiple enzymes in biological systems, which enables high stability of enzymes and efficiency enzymatic cascade catalysis. Nanozymes, a type of nanomaterial with intrinsic enzyme-like characteristics and excellent stabilities, are also widely applied instead of enzymes to construct immobilized cascade systems, achieving better catalytic performance and reaction stability. Due to good stability, reusability, and remarkably high efficiency, the immobilized multi-enzyme/nanozyme biomimetic cascade catalysis systems show distinct advantages in promoting signal transduction and amplification, thereby attracting vast research interest in biosensing applications. This review focuses on the research progress of the immobilized multi-enzyme/nanozyme biomimetic cascade catalysis systems in recent years. The construction approaches, factors affecting the efficiency, and applications for sensitive biosensing are discussed in detail. Further, their challenges and outlooks for future study are also provided.

Implications of analytical nanoscience in pharmaceutical and biomedical fields: A critical view

This review summarizes recent progress performed in the design and application of analytical tools and methodologies using nanomaterials for pharmaceutical analysis, and specifically new nanomedicines at distinct phases of development and translation from preclinical to clinical stages. Over the last 10-15 years, a growing number of studies have utilized various nanomaterials, including carbon-based, metallic nanoparticles, polymeric nanomaterials, materials based on biological molecules, and composite nanomaterials as tools for improving the analysis of pharmaceutical products. New and more complex nanomaterials are currently being explored to influence different stages of the analytical process. These materials provide unique properties to support the extraction of analytes in complex samples, increase the selectivity and efficiency of chromatographic separations, and improve the analytical properties of many sensor applications. Indeed, nanomaterials, including electrochemical detection approaches and biosensing, are expanding at a remarkable rate. Furthermore, the analytical performance of numerous approaches to determine drugs in different matrices can be significantly improved in terms of precision, detection limits, selectivity, and time of analysis. However, the quality control and metrological characterization of the currently synthesized nanomaterials still depend on the development of new and improved analytical methodologies, and the application of specific and improved instrumentation. Therefore, there is still much to explore about the properties of nanomaterials which need to be determined even more precisely and accurately.

Nanoenzymes: A Radiant Hope for the Early Diagnosis and Effective Treatment of Breast and Ovarian Cancers

Breast and ovarian cancers, despite having chemotherapy and surgical treatment, still have the lowest survival rate. Experimental stages using nanoenzymes/nanozymes for ovarian cancer diagnosis and treatment are being carried out, and correspondingly the current treatment approaches to treat breast cancer have a lot of adverse side effects, which is the reason why researchers and scientists are looking for new strategies with less side effects. Nanoenzymes have intrinsic enzyme-like activities and can reduce the shortcomings of naturally occurring enzymes due to the ease of storage, high stability, less expensive, and enhanced efficiency. In this review, we have discussed various ways in which nanoenzymes are being used to diagnose and treat breast and ovarian cancer. For breast cancer, nanoenzymes and their multi-enzymatic properties can control the level of reactive oxygen species (ROS) in cells or tissues, for example, oxidase (OXD) and peroxidase (POD) activity can be used to generate ROS, while catalase (CAT) or superoxide dismutase (SOD) activity can scavenge ROS. In the case of ovarian cancer, most commonly nanoceria is being investigated, and also when folic acid is combined with nanoceria there are additional advantages like inhibition of beta galactosidase. Nanocarriers are also used to deliver small interfering RNA that are effective in cancer treatment. Studies have shown that iron oxide nanoparticles are actively being used for drug delivery, similarly ferritin carriers are used for the delivery of nanozymes. Hypoxia is a major factor in ovarian cancer, therefore MnO2-based nanozymes are being used as a therapy. For cancer diagnosis and screening, nanozymes are being used in sonodynamic cancer therapy for cancer diagnosis and screening, whereas biomedical imaging and folic acid gold particles are also being used for image guided treatments. Nanozyme biosensors have been developed to detect ovarian cancer. This review article summarizes a detailed insight into breast and ovarian cancers in light of nanozymes-based diagnostic and therapeutic approaches.

Multifunctional N, Fe-doped carbon dots with peroxidase-like activity for the determination of H2O2 and ascorbic acid and cell protection against oxidation

Multifunctional N, Fe-doped carbon dots (N, Fe-CDs) were synthesized by the one-step hydrothermal method using ferric ammonium citrate and dicyandiamide as raw materials. The N, Fe-CDs exhibited peroxidase-like (POD) activity by catalyzing the oxidization of 3,3',5,5'-tetramethylbenzidine (TMB) to the green oxidation state ox-TMB in the presence of hydrogen peroxide (H2O2). Subsequently, based on the POD activity of N, Fe-CDs, an efficient and sensitive colorimetric method for the detection of H2O2 and ascorbic acid (AA) was established with a limit of detection of 0.40 µM and 2.05 µM. The proposed detection method has been successfully applied to detect AA in fruit juice, vitamin C tablets, and human serum samples and has exhibited excellent application prospects in biotechnology and food fields. Furthermore, N, Fe-CDs also showed a protective effect on the cell damage caused by H2O2 and could be used as an antioxidant agent.

Natural product nanozymes of herbal extract galangin in managing hepatocellular carcinoma

Numerous local herbal extract species have been investigated as potential medicinal ingredients due to their promising anti-cancer properties. However, the primary constraint of the class of plant flavonoids lies in their low solubility and limited membrane permeability, leading to chemical instability and restricted bioavailability that impede biomedical applications. In this study, we have developed an ideal nanozyme-Galazyme, comprising galangin-loaded copper Nanozyme coated by DSPE-PEG, which amplifies oxidative stress to induce apoptosis via the regulation of reactive oxygen species (ROS) generation and mitogen-activated protein kinase (MAPK) activation. Galazyme exhibited significant peroxidase mimetic activity, demonstrating its potential to generate ROS and elevate oxidative stress. Upon uptake by HepG-2 cells, Galazyme efficiently converts excess hydrogen peroxide (H2O2) into highly reactive •OH radicals and upregulates MAPK expression, leading to the activation of Bax and Caspase 3, thereby promoting irreversible tumor cell apoptosis. Both in vitro and in vivo results demonstrate that Galazyme inhibits tumor cell growth and induces apoptosis by generating ample ROS and activating the MAPK pathway. Our study offers novel evidence supporting the enhancement of Galazyme-induced apoptosis through the upregulation of Bax and Caspase 3, along with the elucidation of the interaction between MAPK and apoptosis.

An ATPase-Mimicking MXene nanozyme pharmacologically breaks the ironclad defense system for ferroptosis cancer therapy

Anticancer nanomedicines used for ferroptosis therapy generally rely on the direct delivery of Fenton catalysts to drive lipid peroxidation in cancer cells. However, the therapeutic efficacy is limited by the ferroptosis resistance caused by the intracellular anti-ferroptotic signals. Herein, we report the intrinsic ATPase-mimicking activity of a vanadium carbide MXene nanozyme (PVCMs) to pharmacologically modulate the nuclear factor erythroid 2-related factor 2 (Nrf2) program, which is the master anti-ferroptotic mediator in the ironclad defense system in triple-negative breast cancer (TNBC) cells. The PVCMs perform high ATPase-like activity that can effectively and selectively catalyze the dephosphorylation of ATP to generate ADP. Through a cascade mechanism initiated by falling energy status, PVCMs can powerfully hinder the Nrf2 program to selectively drive ferroptosis in TNBC cells in response to PVCMs-induced glutathione depletion. This study provides a paradigm for the use of pharmacologically active nanozymes to moderate specific cellular signals and elicit desirable pharmacological activities for therapeutic applications.

Sensitive dual-signal detection and effective removal of tetracycline antibiotics in honey based on a hollow triple-metal organic framework nanozymes

In this work, a colorimetric/fluorescent dual-signal mode sensor is proposed for the sensitive, selective and accurate detection and removal of tetracycline antibiotics (TCs). A triple-metal MOF of NiCoFe is successfully synthesized and controllable adjusted the shape of the hollow structure for the first time, and then modified with TCs aptamer. The as-prepared triple-atom MOF (apt-NiCoFe-MOF-74) exhibits well-defined hollow morphology, high crystallinity, and high surface areas endow their alluring adsorption and removal performances for TCs. More attractively, this triple-metal MOF show a good peroxidase-like activity and strong fluorescence property at 540 nm of apt-NiCoFe-MOF-74 when excitation wavelength was 370 nm. Inspire by this, a dual-signal output biosensor is constructed and the linear absorbance response is well correlated with wide range and low LOD for TCs. The biosensor provided an universal method with satisfactory sensitivity and accuracy for TCs analysis in real food samples.

When nanozymes meet enzyme: Unlocking the dual-activity potential of integrated biocomposites

Integrating enzymes and nanozymes in various applications is a topic of significant interest. The researchers have explored the encapsulation of enzymes using diverse nanostructures to create nanomaterial-enzyme hybrids. These nanomaterials introduce unique properties that contribute to the additional activity along with the stabilization of enzymes in immobilized form, enabling a cascade of second-order reactions. This review centers on dual-activity nanozymes, providing insights into their applications in biosensors and biocatalysis. These applications leverage the enhanced catalytic activity and stability offered by dual-activity nanozymes. These nanozymes find promising applications in fields like bioremediation, offering eco-friendly solutions for mitigating environmental pollution while showing potential in medical diagnostics. The review delves into various techniques for creating enzyme-nanozyme hybrid catalysts, including adsorption, encapsulation, and incorporation methods. The review also addresses the challenges that must be overcome, such as overlapping catalytic surfaces and disparities in reaction rates in multi-enzyme cascade reactions. It concludes by presenting strategies to tackle these issues and offers insights into the field's promising future, suggesting that machine learning may drive further advancements in enzyme-nanozyme integration. This comprehensive exploration illuminates the present and charts a promising course for future innovations in the seamless integration of enzymes and nanozymes, heralding a new era of catalytic possibilities.

Hollow CoFe Nanozymes Integrated with Oncolytic Peptides Designed via Machine-Learning for Tumor Therapy

Developing novel substances to synergize with nanozymes is a challenging yet indispensable task to enable the nanozyme-based therapeutics to tackle individual variations in tumor physicochemical properties. The advancement of machine learning (ML) has provided a useful tool to enhance the accuracy and efficiency in developing synergistic substances. In this study, ML models to mine low-cytotoxicity oncolytic peptides are applied. The filtering Pipeline is constructed using a traversal design and the Autogluon framework. Through the Pipeline, 37 novel peptides with high oncolytic activity against cancer cells and low cytotoxicity to normal cells are identified from a library of 25,740 sequences. Combining dataset testing with cytotoxicity experiments, an 80% accuracy rate is achieved, verifying the reliability of ML predictions. Peptide C2 is proven to possess membranolytic functions specifically for tumor cells as targeted by Pipeline. Then Peptide C2 with CoFe hollow hydroxide nanozyme (H-CF) to form the peptide/H-CF composite is integrated. The new composite exhibited acid-triggered membranolytic function and potent peroxidase-like (POD-like) activity, which induce ferroptosis to tumor cells and inhibits tumor growth. The study suggests that this novel ML-assisted design approach can offer an accurate and efficient paradigm for developing both oncolytic peptides and synergistic peptides for catalytic materials.

Synergizing Pyroelectric Catalysis and Enzyme Catalysis: Establishing a Reciprocal and Synergistic Model to Enhance Anti-Tumor Activity

Nanozyme activity is greatly weakened by the microenvironment and multidrug resistance of tumor cells. Hence, a bi-catalytic nanoplatform, which promotes the anti-tumor activity through "charging empowerment" and "mutual complementation" processes involved in enzymatic and pyroelectric catalysis, by loading ultra-small nanoparticles (USNPs) of pyroelectric ZnSnO3 onto MXene nanozyme (V2CTx nanosheets), is developed. Here, the V2CTx nanosheets exhibit enhanced peroxidase activity by reacting V3+ with H2O2 to generate toxic ·OH, accelerated by the near-infrared (NIR) light mediated heat effect. The resulting V4+ is then converted to V3+ by oxidizing endogenous glutathione (GSH), realizing an enzyme-catalyzed cycle. However, the cycle will lose its persistence once GSH is insufficient; nevertheless, the pyroelectric charges generated by ZnSnO3 USNPs continuously support the V4+/V3+ conversion and ensure nanoenzyme durability. Moreover, the hyperthermia arising from the V2CTx nanosheets by NIR irradiation results in an ideal local temperature gradient for the ZnSnO3 USNPs, giving rise to an excellent pyroelectric catalytic effect by promoting band bending. Furthermore, polarized charges increase the tumor cell membrane permeability and facilitate nanodrug accumulation, thereby resolving the multidrug resistance issue. Thus, the combination of pyroelectric and enzyme catalysis together with the photothermal effect solves the dilemma of nanozymes and improves the antitumor efficiency.

Discovery of neuroprotective Agents: Potent, brain Penetrating, lipoic acid derivatives for the potential treatment of ischemic stroke by regulating oxidative stress and inflammation - a Preliminary study

Stroke poses a serious risk to the physical and mental health of patients. Endogenous compounds are widely used to treat ischemic stroke. Lipoic acid, a naturally occurring (R)-5-(1,2-dithiolan-3-yl)pentanoic acid, has therapeutic potential for the treatment of ischemic stroke. However, the direct application of lipoic acid is limited by its relatively low efficacy and instability. Therefore, there is a need to modify the structure of lipoic acid to improve its pharmaceutical capabilities. Currently, 37 lipoic acid derivatives have been synthesized, and compound AA-9 demonstrated optimal therapeutic potential in an in vitro model of induced oxidative damage using tert-butyl hydroperoxide (t-BHP). In addition, in vitro experiments have shown that compound AA-9 has an excellent safety profile. Subsequently, the therapeutic effect of AA-9 was significant in the rat MCAO ischemic stroke model, which may be attributed to the antioxidant and anti-inflammatory effects of compound AA-9 by activating PGC-1α and inhibiting NLRP3. Notably, compound AA-9 exhibited higher stability and better bioavailability properties than ALA in plasma stability and pharmacokinetic properties. In conclusion, AA-9 may be a promising neuroprotective agent for the treatment of ischemic stroke and warrants further investigation.

Niobium carbide MXenzyme-Driven comprehensive cholesterol regulation for photoacoustic image-guided and anti-inflammatory photothermal ablation in atherosclerosis

Foam cells play a pivotal role in the progression of atherosclerosis progression by triggering inflammation within arterial walls. They release inflammatory molecules that attract additional immune cells, leading to further macrophage recruitment and plaque development. In this study, we develop an osteopontin (OPN) antibody-conjugated niobium carbide (Nb2C-aOPN) MXenzyme designed to selectively target and mildly ablate foam cells while reducing inflammation in the plaque microenvironment. This approach utilizes photonic hyperthermia to decrease plaque size by enhancing cholesterol regulation through both passive cholesterol outflow and positive cholesterol efflux. Nb2C-aOPN MXenzyme exhibits multiple enzyme-mimicking properties, including catalase, superoxide dismutase, peroxidase and glutathione peroxidase, and acts as a scavenger for reactive oxygen and nitrogen species. The inhibition of reactive oxygen and nitrogen species synergizes with photothermal ablation to promote positive cholesterol efflux, leading to reduced macrophage recruitment and a shift in macrophage phenotype from M1 to M2. This integrative strategy on cholesterol regulation and anti-inflammation highlights the potential of multifunctional 2D MXenzyme-based nanomedicine in advancing atherosclerotic regression.