Nanozyme applications in biology and medicine: an overview

High α-lipoic acid-loaded hollow mesoporous prussian blue nanozymes for targeted therapy of nasopharyngeal carcinoma in mice

This study successfully constructs a tumor-targeting α-lipoic acid-loaded hollow mesoporous prussian blue nanozyme (AHPRzyme) for targeted therapy of nasopharyngeal carcinoma in mice. In these nanozymes, Arg-Gly-Asp (RGD) acts as a targeting ligand, enabling effective targeting of tumor cells. Additionally, AHPRzyme exhibits multiple anti-tumor mechanisms: ① The prussian blue nanozymes in AHPRzyme have catalase (CAT) activity, which decomposes H2O2 in human nasopharyngeal carcinoma CEN2 cells into non-toxic H2O, reducing H2O2 levels and minimizing damage to normal cells. The released O2 helps alleviate the hypoxic environment of the tumor, inhibiting lactate production due to hypoxia and consequently suppressing tumor growth. ② The prussian blue nanozymes also have peroxidase (POD) activity, which catalyzes H2O2 in tumor cells to generate ·OH, a reactive oxygen species, leading to tumor cell apoptosis. ③ The α-lipoic acid structure in AHPRzyme contains disulfide bonds that react with GSH, depleting excess glutathione (GSH) in tumor cells, disrupting the oxidative stress balance within the cells, and making them more sensitive to reactive oxygen species, thereby increasing tumor cell apoptosis. In summary, AHPRzyme can inhibit tumor cell growth and promote tumor cell apoptosis by improving the tumor microenvironment, achieving the goal of anti-nasopharyngeal carcinoma therapy.

Nanomineralzyme as a novel sustainable class of nanozyme: Chalcopyrite-based nanozyme for the visual detection of total antioxidant capacity in citrus fruit

Chemically-synthesized Nanozymes that are widely used as alternatives to enzymes face challenges such as high precursor costs, complex preparation processes, and limited catalytic efficiency. To overcome these drawbacks, we introduce naturally derived nanozymes, nanomineralzymes, as a promising alternative, offering benefits like affordability, cost-effectiveness, and scalability. Chalcopyrite (CP, CuFeS2) was sourced from a mineral deposit, and CP nanoparticles were produced by milling. These nanoparticles exhibited strong peroxidase-like activity, achieving a low Michaelis-Menten constant using 3,3',5,5'-tetramethylbenzidine as a substrate. Characterizations revealed the presence of cuprous, cupric, ferrous, and ferric ions in the CP mineral. The proposed mechanism involves an enhanced Fenton and Fenton-like process due to the metal ions' multi-valence states. CP nanozyme activity was inhibited to produce radicals due to hydrogen atom transfer and single electron transfer with ascorbic acid, glutathione and cysteine. The CP mineralzyme-based total antioxidant capacity probe was successfully used for detection of TAC in citrus fruits.

Nanozymes: Innovative Therapeutics in the Battle Against Neurodegenerative Diseases

Neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS) and Huntington's disease (HD), represent a significant challenge to global health due to their progressive nature and the absence of curative treatments. These disorders are characterized by oxidative stress, protein misfolding, and neuroinflammation, which collectively contribute to neuronal damage and death. Recent advancements in nanotechnology have introduced nanozymes-engineered nanomaterials that mimic enzyme-like activities-as promising therapeutic agents. This review explores the multifaceted roles of nanozymes in combating oxidative stress and inflammation in neurodegenerative conditions. By harnessing their potent antioxidant properties, nanozymes can effectively scavenge reactive oxygen species (ROS) and restore redox balance, thereby protecting neuronal function. Their ability to modify surface properties enhances targeted delivery and biocompatibility, making them suitable for various biomedical applications. In this review, we highlight recent findings on the design, functionality, and therapeutic potential of nanozymes, emphasizing their dual role in addressing oxidative stress and pathological features such as protein aggregation. This synthesis of current research underscores the innovative potential of nanozymes as a proactive therapeutic strategy to halt disease progression and improve patient outcomes in neurodegenerative disorders.

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.

Aptamer and DNAzyme Based Colorimetric Biosensors for Pathogen Detection

The detection of pathogens is critical for preventing and controlling health hazards across clinical, environmental, and food safety sectors. Functional nucleic acids (FNAs), such as aptamers and DNAzymes, have emerged as versatile molecular tools for pathogen detection due to their high specificity and affinity. This review focuses on the in vitro selection of FNAs for pathogens, with emphasis on the selection of aptamers for specific biomarkers and intact pathogens, including bacteria and viruses. Additionally, the selection of DNAzymes for bacterial detection is discussed. The integration of these FNAs into colorimetric biosensors has enabled the development of simple, cost-effective diagnostic platforms. Both non-catalytic and catalytic colorimetric biosensors are explored, including those based on gold nanoparticles, polydiacetylenes, protein enzymes, G-quadruplexes, and nanozymes. These biosensors offer visible detection through color changes, making them ideal for point-of-care diagnostics. The review concludes by highlighting current challenges and future perspectives for advancing FNA-based colorimetric biosensing technologies for pathogen detection.

Recent Advances in Metal-Organic Frameworks as Oxidase Mimics: A Comprehensive Review on Rational Design and Modification for Enhanced Sensing Applications

Metal-organic frameworks (MOFs) have emerged as innovative nanozyme mimics, particularly in the area of oxidase catalysis, outperforming traditional MOF-based peroxidase and other nanomaterial-based oxidase systems. This review explores the various advantages that MOFs offer in terms of catalytic activity, low-cost, stability, and structural versatility. With a primary focus on their application in biochemical sensing, MOF-based oxidases have demonstrated remarkable utility, prompting a thorough exploration of their design and modification strategies. Moreover, the review aims to provide a comprehensive analysis of the strategies employed in the rational design and modification of MOF structures to optimize key parameters such as sensitivity, selectivity, and stability in the context of biochemical sensors. Through an exhaustive examination of recent research and developments, this article seeks to offer insights into the nuanced interplay between MOF structures and their catalytic performance, shedding light on the mechanisms that underpin their effectiveness as nanozyme mimics. Finally, this review addresses challenges and opportunities associated with MOF-based oxidase mimics, aiming to drive further advancements in MOF structure design and the development of highly effective biochemical sensors for diverse applications.

Smartphone-integrated colorimetric sensor for rapid detection of phenolic compounds based on the peroxidase-mimicking activity of copper/cerium-aspartic acid metal-organic framework

A smartphone-integrated colorimetric sensor is introduced for the rapid detection of phenolic compounds, including 8-hydroquinone (HQ), p-nitrophenol (NP), and catechol (CC). This sensor relies on the peroxidase-mimicking activity of aspartate-based metal-organic frameworks (MOFs) such as Cu-Asp, Ce-Asp, and Cu/Ce-Asp. These MOFs facilitate the oxidation of a colorless substrate, 3,3',5,5'-tetramethylbenzidine (TMB), by reactive oxygen species (ROS) derived from hydrogen peroxide (H2O2), resulting in the formation of blue-colored oxidized TMB (ox-TMB). Among the synthesized MOFs, Cu/Ce-Asp nanorods had the highest activity, probably due to the synergistic effect of aspartate and copper coordination, as well as their large surface area, which allows for improved electron transport. Consequently, Cu/Ce-Asp nanorods were utilized for the detection of phenolic compounds under optimized conditions. In the presence of phenolic compounds, the interaction between TMB and H2O2 is inhibited, resulting in various colorimetric responses. This method accurately determined HQ, NP, and CC in a linear range of up to 5 μM, with detection limits of 0.30 μM, 0.76 μM, and 0.50 μM, respectively. To facilitate real-time and portable analysis, smartphone technology was integrated for color detection, eliminating the need for expensive and bulky laboratory-based optical instruments. In addition, the sensor was effectively employed for real water sample analysis, yielding satisfactory recovery outcomes. The proposed sensor offers a rapid, user-friendly, and portable method for detecting phenolic compounds, even at low concentrations. This study not only advances the application of MOF-based nanozymes in environmental monitoring but also expands their potential use in other fields.

Onion-Like Carbon Nanozyme: Controlling Peroxidase-Like Activity by Carbon Hybridization Patterns for Antibacterial Therapy

Since the inception of the concept of nanozymes, there has been a growing interest in the rational design and controllable synthesis of nanozymes with adjustable activities. In this study, onion-liked carbon (OLC) with remarkable peroxidase-like (POD) activity are developed through delicately controlling the sp2/sp3 configuration. The investigation reveals that enzymatic activity of OLC increases first and then decreases with the increased graphitic degree, with the highest activity observed at a moderate sp2/sp3 ratio of 17.17%. A series of experiments and theoretical calculations are conducted to elucidate the catalytic mechanism, and the structure-dependent activity is attributed to a synergistic effect of surface adsorption and electron transfer processes. The POD activity enables the OLC to catalyze the decomposition of H2O2, producing reactive oxygen species for eradicating Gram-positive and Gram-negative bacteria. Additionally, toxicity tests based on nematode and mouse models confirmed the excellent biocompatibility of OLC. Furthermore, the OLC exhibited antibacterial ability and promoted bacterial-infected wound healing in a mouse model. This work not only gives a deeper understanding of the structure-activity relationship and catalytic mechanism of carbon-based nanozymes, but also unveils a novel avenue for antibacterial therapy and wound healing applications.

Immunomodulatory metal-based biomaterials for cancer immunotherapy

Cancer immunotherapy, as an emerging cancer treatment approach, harnesses the patient's own immune system to effectively prevent tumor recurrence or metastasis. However, its clinical application has been significantly hindered by relatively low immune response rates. In recent years, metal-based biomaterials have been extensively studied as effective immunomodulators and potential tools for enhancing anti-tumor immune responses, enabling the reversal of immune suppression without inducing toxic side effects. This review introduces the classification of bioactive metal elements and summarizes their immune regulatory mechanisms. In addition, we discuss the immunomodulatory roles of biomaterials constructed from various metals, including aluminum, manganese, gold, calcium, zinc, iron, magnesium, and copper. More importantly, a systematic overview of their applications in enhancing immunotherapy is provided. Finally, the prospects and challenges of metal-based biomaterials with immunomodulatory functions in cancer immunotherapy are outlined.

Emerging Roles of Nanozymes in Plant and Environmental Sectors

The demand for food has increased dramatically as the global population increases, putting more strain on the sustainability of agriculture. To fulfill this requirement, it is imperative to develop brand-new technologies. The application potential of nanozymes in the plant and environmental sectors is progressively becoming apparent as a result of their effective enzymatic catalytic activity and the distinctive characteristics of nanomaterials, including size, specific surface area, optical properties, and thermal properties. Herein, we systematically analyze the catalytic mechanisms of nanozymes with different enzyme-mimetic activities and summarize their applications in improving crop yields by regulating ROS levels and enhancing stress resistance and detecting and removing hazardous pollutants. Finally, we thoroughly analyze the challenges faced by nanozymes regarding size, design, application, economy, and biosafety and look forward to their future development directions to better serve sustainable agriculture.

Construction of Smartphone-Integrated Nanozyme Sensor Based on Amino Acid-Modulated Gold Nanoparticles

Amino acids are not only the building blocks of proteins but also lead to the development of novel nanomaterials with unique properties. Herein, we proposed a simple strategy to produce gold nanoparticles (Au NPs) with peroxidase-like (POD-like) activities by using a series of amino acids as reducing agents, named Au NPs@M (M represents different amino acids). The Au NPs@His was identified as the nanozyme with the most potent catalytic performance, which was used in combination with smartphones to achieve rapid detection of hydrogen peroxide with a detection limit of 0.966 μM. It also enables rapid detection of glucose with a detection limit of 2.904 μM, highlighting the significant contribution of Au NPs@His in expediting the detection of critical biomolecules. This work not only provides a convenient and highly efficient method to identify glucose but also shows the potential of histidine as a reducing agent in constructing Au nanomaterials exerting enzyme-like catalysis.

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.

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.

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.

A metal-phenolic coordination framework nanozyme exhibits dual enzyme mimicking activity and its application is effective for colorimetric detection of biomolecules

Biomolecules play vital roles in many biological processes and diseases, making their identification crucial. Herein, we present a colorimetric sensing method for detecting biomolecules like cysteine (Cys), homocysteine (Hcy), and glutathione (GSH). This approach is based on a reaction system whereby colorless 3,3',5,5'-tetramethylbenzidine (TMB) undergoes catalytic oxidation to form blue-colored oxidized TMB (ox-TMB) in the presence of hydrogen peroxide (H2O2), utilizing the peroxidase and catalase-mimicking activities of metal-phenolic coordination frameworks (MPNs) of Cu-TA, Co-TA, and Fe-TA nanospheres. The Fe-TA nanospheres demonstrated superior activity, more active sites and enhanced electron transport. Under optimal conditions, the Fe-TA nanospheres were used for the detection of biomolecules. When present, biomolecules inhibit the reaction between TMB and H2O2, causing various colorimetric responses at low detection limits of 0.382, 0.776 and 0.750 μM for Cys, Hcy and GSH. Furthermore, it was successfully applied to real water samples with good recovery results. The developed sensor not only offers a rapid, portable, and user-friendly technique for multi-target analysis of biomolecules at low concentrations but also expands the potential uses of MPNs for other targets in the environmental field.

Nanozymes with biomimetically designed properties for cancer treatment

Nanozymes, as a type of nanomaterials with enzymatic catalytic activity, have demonstrated tremendous potential in cancer treatment owing to their unique biomedical properties. However, the heterogeneity of tumors and the complex tumor microenvironment pose significant challenges to the in vivo catalytic efficacy of traditional nanozymes. Drawing inspiration from natural enzymes, scientists are now using biomimetic design to build nanozymes from the ground up. This approach aims to replicate the key characteristics of natural enzymes, including active structures, catalytic processes, and the ability to adapt to the tumor environment. This achieves selective optimization of nanozyme catalytic performance and therapeutic effects. This review takes a deep dive into the use of these biomimetically designed nanozymes in cancer treatment. It explores a range of biomimetic design strategies, from structural and process mimicry to advanced functional biomimicry. A significant focus is on tweaking the nanozyme structures to boost their catalytic performance, integrating them into complex enzyme networks similar to those in biological systems, and adjusting functions like altering tumor metabolism, reshaping the tumor environment, and enhancing drug delivery. The review also covers the applications of specially designed nanozymes in pan-cancer treatment, from catalytic therapy to improved traditional methods like chemotherapy, radiotherapy, and sonodynamic therapy, specifically analyzing the anti-tumor mechanisms of different therapeutic combination systems. Through rational design, these biomimetically designed nanozymes not only deepen the understanding of the regulatory mechanisms of nanozyme structure and performance but also adapt profoundly to tumor physiology, optimizing therapeutic effects and paving new pathways for innovative cancer treatment.

Dual-mode colorimetric and photothermal aptasensor for detection of kanamycin using flocculent platinum nanoparticles

Chitosan (CS)-stabilized platinum nanoparticles (CS/PtNPs) were employed to develop a novel aptamer-based dual-mode colorimetric and photothermal biosensor for selective detection of kanamycin (KAN). As a peroxidase-like catalyst, the CS/PtNPs showed outstanding catalytic activity for the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2). As a stabilizing agent, CS excelled at fixing the KAN binding aptamer on the surface of the CS/PtNPs, amplifying their catalytic activity and enhancing colloidal dispersion and stability. The oxidized TMB (TMBox) functioned as a signal for the colorimetric, photothermal aptasensor because of its observable absorbance of light in the visible and near-infrared (NIR) regions. When light from a NIR laser was absorbed by the TMBox in the reaction solution, heat was generated in inverse proportion to the KAN concentration. The developed colorimetric and photothermal modes of the aptasensor showed a linear detection range of 0.1-50 and 0.5-50 μM, with a limit of detection (LOD) of 0.04 and 0.41 μM, respectively. Moreover, the aptasensor successfully determined KAN concentrations in spiked milk samples, verifying the reliability and reproducibility in practical applications. The dual-mode aptasensor based on CS/PtNPs for KAN detection, utilizing both color change and heat generation signals through a single probe (TMBox), demonstrates rapid response, simplicity in operation, cost-effectiveness, and high sensitivity. In addition, unlike typical immunoassays, this aptamer-based peroxidase-like nanozyme activation and inhibition strategy required no washing process, which was very effective in terms of reducing the time required for an assay and sustaining a high sensitivity.

Effects and mechanisms of prussian blue nanozymes with multiple enzyme activities on nasopharyngeal carcinoma cells

Prussian blue nanozymes (PBNs) with multiple enzyme activities are prepared and their activities of antitumor in nasopharyngeal carcinoma cells (CEN2) are also explored in this research. On the one hand, it shows that PBNs can exert the catalase-like (CAT-like) activity to decompose hydrogen peroxide (H2O2) into non-toxic H2O in CEN2 cells. The O2 release of H2O2 catalysed by PBNs effectively alleviates the hypoxic environment of tumors, which inhibits the glycolysis of tumor and reduces the production of lactic acid. On the other hand, we also find that PBNs also has peroxidase-like (POD-like) enzymatic activity, which can catalyze the production of·OH from H2O2 in tumor cells and result in tumor cell apoptosis. This study lays a solid biomedical foundation for the development of safe and non-toxic nanozymes, as well as the expansion of their application in tumor treatment.

Tumor microenvironment-activated theranostic nanoreactor for NIR-II Photoacoustic imaging-guided tumor-specific photothermal therapy

Theranostic agents that can be sensitively and specifically activated by the tumor microenvironment (TME) have recently attracted considerable attention. In this study, TME-activatable 3,3',5,5'-tetramethylbenzidine (TMB)-copper peroxide (CuO2)@poly(lactic-co-glycolic acid) (PLGA)@red blood cell membrane (RBCM) (TCPR) nanoparticles (NPs) for second near-infrared photoacoustic imaging-guided tumor-specific photothermal therapy were developed by co-loading CuO2 NPs and TMB into PLGA camouflaged by RBCMs. As an efficient H2O2 supplier, once exposed to a proton-rich TME, CuO2 NPs can generate H2O2 and Cu2+, which are further reduced to Cu+ by endogenous glutathione. Subsequently, the Cu+-mediated Fenton-like reaction produces cytotoxic ·OH to kill the cancer cells and induce TMB-mediated photoacoustic and photothermal effects. Combined with the RBCM modification-prolonged blood circulation, TCPR NPs display excellent specificity and efficiency in suppressing tumor growth, paving the way for more accurate, safe, and efficient cancer theranostics.

A highly sensitive colorimetric DNA sensor for MicroRNA-155 detection: leveraging the peroxidase-like activity of copper nanoparticles in a double amplification strategy

A novel and highly sensitive colorimetric DNA sensor for determination of miRNA-155 at attomolar levelsis presented that combines the peroxidase-like activity of copper nanoparticles (CuNPs) with the hybridization chain reaction (HCR) . The utilization of CuNPs offers advantages such as strong interaction with double-stranded DNA, excellent molecular recognition, and mimic catalytic activity. Herein, a capture probe DNA (P1) was immobilized on carboxylated magnetic beads (MBs), allowing for amplified immobilization due to the 3D surface. Subsequently, the presence of the target microRNA-155 led to the formation of a sandwich structure (P2/microRNA-155/P1/MBs) when P2 was introduced to the modified P1/MBs. The HCR reaction was then triggered by adding H1 and H2 to create a super sandwich (H1/H2)n. Following this, Cu2+ ions were attracted to the negatively charged phosphate groups of the (H1/H2)n and reduced by ascorbic acid, resulting in the formation of CuNPs, which were embedded into the grooves of the (H1/H2)n. The peroxidase-like activity of CuNPs catalyzed the oxidation reaction of 3,3',5,5'-Tetramethylbenzidine (TMB), resulting in a distinct blue color measured at 630 nm. Under optimal conditions, the colorimetric biosensor exhibited a linear response to microRNA-155 concentrations ranging from 80 to 500 aM, with a detection limit of 22 aM, and discriminate against other microRNAs. It was also successfully applied to the determination of microRNA-155 levels in spiked human serum.

Piezoelectric Effect Modulates Nanozyme Activity: Underlying Mechanism and Practical Application

Nanozyme activity relies on surface electron transfer processes. Notably, the piezoelectric effect plays a vital role in influencing nanozyme activity by generating positive and negative charges on piezoelectric materials' surfaces. This article comprehensively reviews the potential mechanisms and practical applications of regulating nanozyme activity through the piezoelectric effect. The article first elucidates how the piezoelectric effect enables nanozymes to exhibit catalytic activity. It is highlighted that the positive and negative charges produced by this effect directly participate in redox reactions, leading to the conversion of materials from an inactive to an active state. Moreover, the piezoelectric field generated can enhance nanozyme activity by accelerating electron transfer rates or reducing binding energy between nanozymes and substrates. Practical applications of piezoelectric nanozymes are explored in the subsequent section, including water pollutant degradation, bacterial disinfection, biological detection, and tumor therapy, which demonstrate the versatile potentials of the piezoelectric effect in nanozyme applications. The review concludes by emphasizing the need for further research into the catalytic mechanisms of piezoelectric nanozymes, suggesting expanding the scope of catalytic types and exploring new application areas. Furthermore, the promising direction of synergistic catalytic therapy is discussed as an inspiring avenue for future research.

Synthesis of Two-Dimensional (Cu-S)n Metal-Organic Framework Nanosheets Applied as Peroxidase Mimics for Detection of Glutathione

Facilely synthesized peroxidase-like nanozymes with high catalytic activity and stability may serve as effective biocatalysts. The present study synthesizes peroxidase-like nanozymes with multinuclear active sites using two-dimensional (2D) metal-organic framework (MOF) nanosheets and evaluates them for their practical applications. A simple method involving a one-pot bottom-up reflux reaction is developed for the mass synthesis of (Cu-S)n MOF 2D nanosheets, significantly increasing production quantity and reducing reaction time compared to traditional autoclave methods. The (Cu-S)n MOF 2D nanosheets with the unique coordination of Cu(I) stabilized in Cu-based MOFs demonstrate impressive activity in mimicking natural peroxidase. The active sites of the peroxidase-like activity of (Cu-S)n MOF 2D nanosheets were predominantly verified as Cu(I) rather than Cu(II) of other Cu-based MOFs. The cost-effective and long-term stability of (Cu-S)n MOF 2D nanosheets make them suitable for practical applications. Furthermore, the inhibition of the peroxidase-like activity of (Cu-S)n MOF nanosheets by glutathione (GSH) could provide a simple strategy for colorimetric detection of GSH against other amino acids. This work remarkably extends the utilization of (Cu-S)n MOF 2D nanosheets in biosensing, revealing the potential for 2D (Cu-S)n MOFs.

Nanozyme: a rising star for cancer therapy

In recent years, nanozymes have attracted enormous attention due to their effectiveness in promoting various catalytic reactions. To date, thousands of nanozymes have been discovered, including oxidase-like nanozymes, peroxidase-like nanozymes, and catalase-like nanozymes, covering noble metal, transition metal, and carbon nanomaterials. These nanozymes have been widely applied in various fields, including environmental protection, biosensing and nanomedicine. There are many reviews about this rising star being used in analytical chemistry. However, few works about nanozymes were related to cancer therapy. In this study, we comprehensively summarize the latest research advances on the strategies for cancer therapy based on different nanozymes. With traditional cancer treatment (including chemotherapy, radiotherapy, phototherapy), nanozyme catalytic therapy exhibited a synergistic effect for limiting the growth of tumors. Opportunities and trends for nanozymes in future cancer therapy are also discussed.

Coordination-Driven One-Step Rapid Self-Assembly Synthesis of Dual-Functional Ag@Pt Nanozyme

Realizing high-precise and adjustable regulation of engineering nanozyme is important in nanotechnology. Here, Ag@Pt nanozymes with excellent peroxidase-like and antibacterial effects are designed and synthesized by nucleic acid and metal ions coordination-driven one-step rapid self-assembly. The adjustable NA-Ag@Pt nanozyme is synthesized within 4 min using single-stranded nucleic acid as templates, and peroxidase-like enhancing FNA-Ag@Pt nanozyme is received by regulating functional nucleic acids (FNA) based on NA-Ag@Pt nanozyme. Both Ag@Pt nanozymes that are developed not only has simple and general synthesis approaches, but also can produce artificial precise adjustment and possess dual-functional. Moreover, when lead ion-specific aptamers as FNA are introduced to NA-Ag@Pt nanozyme, the Pb2+ aptasensor is successfully constructed by increasing electron conversion efficiency and improving the specificity of nanozyme. In addition, both nanozyme has good antibacterial properties, with ~100% and ~85% antibacterial efficiency against Escherichia coli and Staphylococcus aureus, respectively. This work provides a synthesis method of novelty dual-functional Ag@Pt nanozymes and successful application in metal ions detection and antibacterial agents.

Development of nanozyme based sensors as diagnostic tools in clinic applications: a review

Since 1970, many artificial enzymes that imitate the activity and structure of natural enzymes have been discovered. Nanozymes are a group of nanomaterials with enzyme-mimetic properties capable of catalyzing natural enzyme processes. Nanozymes have attracted great interest in biomedicine due to their excellent stability, rapid reactivity, and affordable cost. The enzyme-mimetic activities of nanozymes may be modulated by numerous parameters, including the oxidative state of metal ions, pH, hydrogen peroxide (H2O2) level, and glutathione (GSH) concentration, indicating the tremendous potential for biological applications. This article delivers a comprehensive overview of the advances in the knowledge of nanozymes and the creation of unique and multifunctional nanozymes, and their biological applications. In addition, a future perspective of employing the as-designed nanozymes in biomedical and diagnostic applications is provided, and we also discuss the barriers and constraints for their further therapeutic use.

Apta-sensor for selective determination of dopamine using chitosan-stabilized Prussian blue nanoparticles

Chitosan-stabilized Prussian blue nanoparticles (CS/PBNPs) were fabricated by a simple synthetic method and used to develop a novel aptamer-based colorimetric assay for selective determination of dopamine (DA). Scanning electron microscopy (SEM) images exhibited a uniform shape of the CS/PBNPs with an average diameter of 37.0 ± 3.2 nm. The CS/PBNPs exhibited strong peroxidase-like activity that catalyzed the reaction between 3,3',5,5'-tetramethylbenzidine (TMB) and hydrogen peroxide (H₂O₂). Chitosan was used for stabilization of the PBNPs and fixation of the DA aptamer on the surface of the CS/PBNPs. The catalytic mechanism of the CS/PBNPs was confirmed to involve first the decomposition of H₂O₂ into a hydroxyl radical (˙OH) and then oxidation of TMB by the ˙OH to produce a blue color. An aptamer-based colorimetric assay was made with the CS/PBNPs to detect DA at concentrations of 0.25-100 μM with a limit of detection (LOD) of 0.16 μM. For comparison, a gold nanoparticle (AuNP)-based apta-sensor detected DA in concentrations of 1-25 μM with a LOD of 0.55 μM. The recovery results of DA concentrations (0.25, 0.5, and 1 μM) from spiked human serum were 92.6%, 102.1%, and 103.9%, verifying the reliability and reproducibility of the CS/PBNP-based apta-sensor for determination of DA level in clinical applications. Moreover, compared to traditional immunoassay, this aptamer-based nanozyme activation/inhibition system needs no washing step, which is very useful to shorten the assay time and maintain high sensitivity.

Application of Nanozymes in Environmental Monitoring, Management, and Protection

Nanozymes are nanomaterials with enzyme-like activity, possessing the unique properties of nanomaterials and natural enzyme-like catalytic functions. Nanozymes are catalytically active, stable, tunable, recyclable, and versatile. Therefore, increasing attention has been paid in the fields of environmental science and life sciences. In this review, we focused on the most recent applications of nanozymes for environmental monitoring, environmental management, and environmental protection. We firstly introduce the tuning catalytic activity of nanozymes according to some crucial factors such as size and shape, composition and doping, and surface coating. Then, the application of nanozymes in environmental fields are introduced in detail. Nanozymes can not only be used to detect inorganic ions, molecules, organics, and foodborne pathogenic bacteria but are also involved in the degradation of phenolic compounds, dyes, and antibiotics. The capability of nanozymes was also reported for assisting air purification, constructing biofuel cells, and application in marine antibacterial fouling removal. Finally, the current challenges and future trends of nanozymes toward environmental fields are proposed and discussed.

Smart Biomimetic Nanozymes for Precise Molecular Imaging: Application and Challenges

New nanotechnologies for imaging molecules are widely being applied to visualize the expression of specific molecules (e.g., ions, biomarkers) for disease diagnosis. Among various nanoplatforms, nanozymes, which exhibit enzyme-like catalytic activities in vivo, have gained tremendously increasing attention in molecular imaging due to their unique properties such as diverse enzyme-mimicking activities, excellent biocompatibility, ease of surface tenability, and low cost. In addition, by integrating different nanoparticles with superparamagnetic, photoacoustic, fluorescence, and photothermal properties, the nanoenzymes are able to increase the imaging sensitivity and accuracy for better understanding the complexity and the biological process of disease. Moreover, these functions encourage the utilization of nanozymes as therapeutic agents to assist in treatment. In this review, we focus on the applications of nanozymes in molecular imaging and discuss the use of peroxidase (POD), oxidase (OXD), catalase (CAT), and superoxide dismutase (SOD) with different imaging modalities. Further, the applications of nanozymes for cancer treatment, bacterial infection, and inflammation image-guided therapy are discussed. Overall, this review aims to provide a complete reference for research in the interdisciplinary fields of nanotechnology and molecular imaging to promote the advancement and clinical translation of novel biomimetic nanozymes.

Progress and perspectives of platinum nanozyme in cancer therapy

Malignant tumors, one of the worst-case scenarios within human health problems, are now posing an increasing threat to the well-being of the global population. At present, the treatment of malignant tumors mainly includes surgery, radiotherapy, chemotherapy, immunotherapy, etc. Radiotherapy and chemotherapy are often applied to inoperable tumors, and some other tumors after surgery as important adjuvant therapies. Nonetheless, both radiotherapy and chemotherapy have a series of side effects, such as radiation-induced lung injury, and chemotherapy-induced bone marrow suppression. In addition, the positioning accuracy of radiotherapy and chemotherapy is not assured and satisfactory, and the possibility of tumor cells not being sensitive to radiation and chemotherapy drugs is also problematic. Nanozymes are nanomaterials that display natural enzyme activities, and their applications to tumor therapy have made great progress recently. The most studied one, platinum nanozyme, has been shown to possess a significant correlation with radiotherapy sensitization of tumors as well as photodynamic therapy. However, there are still several issues that limited the usage of platinum-based nanozymes in vivo. In this review, we briefly summarize the representative studies regarding platinum nanozymes, and especially emphasize on the current challenges and the directions of future development for platinum nanozymes therapy.

Thiolated gamma-cyclodextrin-polymer-functionalized CeFe3O4 magnetic nanocomposite as an intrinsic nanocatalyst for the selective and ultrasensitive colorimetric detection of triacetone triperoxide

Explosives are powerful destructive weapons used by criminals and terrorists across the globe and their use within military installation sites poses serious environmental health problems. Existing colorimetric sensors for triacetone triperoxide (TATP) relies on detecting its hydrolysed H₂O₂ form. However, such detection strategy limits the practicability for on-site TATP sensing. In this work, we have developed a novel peroxidase mimic catalytic colorimetric sensor for direct recognition of TATP. Ceria (Ce)-doped Fe₃O₄ nanoparticles (CeFe₃O₄) were synthesized via the hot-injection organic synthetic route in the presence of metal precursors and organic ligands. Thereafter, the organic-capped CeFe₃O₄ nanoparticles were surface-functionalized with amphiphilic polymers (Amp-poly) to render the nanoparticle stable, compact and biocompatible. Thiolated γ-cyclodextrin (γ-CD) was adsorbed on the Amp-poly-CeFe₃O₄ nanocomposite (NC) surface to form a γ-CD-Amp-poly-CeFe₃O₄ NC. γ-CD served both as a receptor and as a catalytic enhancer for TATP. Hemin (H), used as a catalytic signal amplifier was adsorbed on the γ-CD-Amp-poly-CeFe₃O₄ NC surface to form a γ-CD-Amp-poly-CeFe₃O₄-H NC that served as a functional nanozyme for the enhanced catalytic colorimetric detection of TATP. Under optimum experimental reaction conditions, TATP prepared in BIS-TRIS-Trisma Ac-KAc-NAc buffer, pH 3, was selectively and ultrasensitively detected without the need for acid hydrolysis based on the catalytic oxidation of 3,3',5,5'-tetramethylbenzidine by H₂O₂ in the presence of the γ-CD-Amp-poly-CeFe₃O₄-H hybrid nanozyme. The obtained limit of detection of ∼0.05 μg/mL when compared with other published probes demonstrated superior sensitivity. The developed peroxidase mimic γ-CD-Amp-poly-CeFe₃O₄-H catalytic colorimetric sensor was successfully applied to detect TATP in soil, river water and tap water samples.

Exploring the Antibacterial and Biosensing Applications of Peroxidase-Mimetic Ni0.1Cu0.9S Nanoflower

Nanozymes, as artificial enzymes with the biological action of natural enzymes, have enormous potential in the fields of disease diagnosis, bacteriostasis, biosensing, etc. In this work, the Ni_0.1Cu_0.9S nanoflower was successfully synthesized through a one-step hydrothermal method. A combined strategy of Ni doping and morphology design was employed to adjust its electronic structure and active sites, endowing the Ni_0.1Cu_0.9S nanoflower with excellent peroxidase-like activity. Therefore, it can catalyze the decomposition of H₂O₂ to generate •OH with higher antibacterial activity, establishing a broad-spectrum antibacterial system based on the Ni_0.1Cu_0.9S nanoflower against E. coli and S. aureus, which avoids the harm of a high concentration of H₂O₂. Additionally, the colorless substrate TMB can be catalytically oxidized into blue ox-TMB via •OH. As a result, a colorimetric technique with rapid and accurate detection of ascorbic acid (AA) by the unaided eye was designed, in view of the specific inhibition effect towards the oxidation of TMB. This detection platform has a wide linear range (10~800 μM) with a low limit of detection (0.84 μM) and exhibits a satisfactory selectivity toward the detection of AA. This study sheds new light on the application of copper-containing nanozymes in the fields of biomedicine and bioassay.

Improving the sensitivity of lateral flow immunoassay for Salmonella typhimurium detection via flow-rate regulation

Application of the traditional immunochromatographic assay (ICGA) has been limited by its poor sensitivity. The objective of this study was to increase the sensitivity of the traditional ICGA. A dual-mode ICGA (D-M ICGA) was developed by combining a nanozyme-assisted signal-amplification strategy with a magnetic-nanoparticle-based flow-speed-control strategy. Salmonella typhimurium can be detected simultaneously based on color and magnetic signals in the detection area of the D-M ICGA strip. The calculated limits of detection of 50 cfu·mL^-1 and 75 cfu·mL^-1 in the color and magnetic modes, respectively, were approximately 1000 times lower than those of the traditional ICGA. The selectivity and practical applicability of the D-M ICGA were also confirmed in this study. The results prove that the D-M ICGA is an assay that could be used for Salmonella typhimurium detection and can be easily adapted to detect other pathogenic bacteria.

Modular configurations of living biomaterials incorporating nano-based artificial mediators and synthetic biology to improve bioelectrocatalytic performance: A review

Currently, the industrial application of bioelectrochemical systems (BESs) that are incubated with natural electrochemically active microbes (EABs) is limited due to inefficient extracellular electron transfer (EET) by natural EABs. Notably, recent studies have identified several novel living biomaterials comprising highly efficient electron transfer systems allowing unparalleled proficiency of energy conversion. Introduction of these biomaterials into BESs could fundamentally increase their utilization for a wide range of applications. This review provides a comprehensive assessment of recent advancements in the design of living biomaterials that can be exploited to enhance bioelectrocatalytic performance. Further, modular configurations of abiotic and biotic components promise a powerful enhancement through integration of nano-based artificial mediators and synthetic biology. Herein, recent advancements in BESs are synthesized and assessed, including heterojunctions between conductive nanomaterials and EABs, in-situ hybrid self-assembly of EABs and nano-sized semiconductors, cytoprotection in biohybrids, synthetic biological modifications of EABs and electroactive biofilms. Since living biomaterials comprise a broad range of disciplines, such as molecular biology, electrochemistry and material sciences, full integration of technological advances applied in an interdisciplinary framework will greatly enhance/advance the utility and novelty of BESs. Overall, emerging fundamental knowledge concerning living biomaterials provides a powerful opportunity to markedly boost EET efficiency and facilitate the industrial application of BESs to meet global sustainability challenges/goals.

CoO Nanozymes with Multiple Catalytic Activities Regulate Atopic Dermatitis

Herein, we prepared CoO nanozymes with three types of enzyme catalytic activities for the first time, which have SOD-like, CAT-like, and POD-like catalytic activities. This is the first study to report the preparation of CoO nanoparticles with three types of enzyme catalytic activities by the one-pot method. By modifying the surface of CoO nanozymes with a carboxyl group, its biocompatibility enhanced, so it can be used in the field of life sciences. In vitro cytotoxicity and anti-H2O2-induced ROS experiments proved that CoO nanozymes can protect HaCaT cells against ROS and cytotoxicity induced by H2O2. In addition, an atopic dermatitis (AD) mouse model was established by topical application of MC903, which verified the anti-inflammatory effect of CoO nanozymes on the AD mouse model. Traditional drugs for the treatment of AD, such as dexamethasone, have significant side-effects. The side-effects include skin burns, telangiectasias, and even serious drug dependence. CoO nano-enzymes have a low cytotoxicity and its multiple enzyme-like catalytic activities can effectively protect cells and tissues in ROS environments, which proves that CoO nano-enzymes have high application potential in the field of anti-inflammation.

A Review of Advanced Molecular Engineering Approaches to Enhance the Thermostability of Enzyme Breakers: From Prospective of Upstream Oil and Gas Industry

During the fracture stimulation of oil and gas wells, fracturing fluids are used to create fractures and transport the proppant into the fractured reservoirs. The fracturing fluid viscosity is responsible for proppant suspension, the viscosity can be increased through the incorporation of guar polymer and cross-linkers. After the fracturing operation, the fluid viscosity is decreased by breakers for efficient oil and gas recovery. Different types of enzyme breakers have been engineered and employed to reduce the fracturing fluid′s viscosity, but thermal stability remains the major constraint for the use of enzymes. The latest enzyme engineering approaches such as direct evolution and rational design, have great potential to increase the enzyme breakers’ thermostability against high temperatures of reservoirs. In this review article, we have reviewed recently advanced enzyme molecular engineering technologies and how these strategies could be used to enhance the thermostability of enzyme breakers in the upstream oil and gas industry.

Repurposing ferumoxytol: Diagnostic and therapeutic applications of an FDA-approved nanoparticle

Ferumoxytol is an intravenous iron oxide nanoparticle formulation that has been approved by the U.S. Food and Drug Administration (FDA) for treating anemia in patients with chronic kidney disease. In recent years, ferumoxytol has also been demonstrated to have potential for many additional biomedical applications due to its excellent inherent physical properties, such as superparamagnetism, biocatalytic activity, and immunomodulatory behavior. With good safety and clearance profiles, ferumoxytol has been extensively utilized in both preclinical and clinical studies. Here, we first introduce the medical needs and the value of current iron oxide nanoparticle formulations in the market. We then focus on ferumoxytol nanoparticles and their physicochemical, diagnostic, and therapeutic properties. We include examples describing their use in various biomedical applications, including magnetic resonance imaging (MRI), multimodality imaging, iron deficiency treatment, immunotherapy, microbial biofilm treatment and drug delivery. Finally, we provide a brief conclusion and offer our perspectives on the current limitations and emerging applications of ferumoxytol in biomedicine. Overall, this review provides a comprehensive summary of the developments of ferumoxytol as an agent with diagnostic, therapeutic, and theranostic functionalities.

A two-dimensional thin Co-MOF nanosheet as a nanozyme with high oxidase-like activity for GSH detection

A two-dimensional thin Co-MOF (ZIF-67) nanosheet with high oxidase-like activity was applied for sensitive visual GSH detection.

High surface area nitrogen-functionalized Ni nanozymes for efficient peroxidase-like catalytic activity

Nitrogen-functionalization is an effective means of improving the catalytic performances of nanozymes. In the present work, plasma-assisted nitrogen modification of nanocolumnar Ni GLAD films was performed using an ammonia plasma, resulting in an improvement in the peroxidase-like catalytic performance of the porous, nanostructured Ni films. The plasma-treated nanozymes were characterized by TEM, SEM, XRD, and XPS, revealing a nitrogen-rich surface composition. Increased surface wettability was observed after ammonia plasma treatment, and the resulting nitrogen-functionalized Ni GLAD films presented dramatically enhanced peroxidase-like catalytic activity. The optimal time for plasma treatment was determined to be 120 s; when used to catalyze the oxidation of the colorimetric substrate TMB in the presence of H2O2, Ni films subjected to 120 s of plasma treatment yielded a much higher maximum reaction velocity (3.7⊆10-8 M/s vs. 2.3⊆10-8 M/s) and lower Michaelis-Menten coefficient (0.17 mM vs. 0.23 mM) than pristine Ni films with the same morphology. Additionally, we demonstrate the application of the nanozyme in a gravity-driven, continuous catalytic reaction device. Such a controllable plasma treatment strategy may open a new door toward surface-functionalized nanozymes with improved catalytic performance and potential applications in flow-driven point-of-care devices.

A metastasis suppressor Pt-dendrimer nanozyme for the alleviation of glioblastoma

Nanozymes are nanostructure-based materials which mimic the enzymatic characteristics of natural enzymes. Biological applications of nanozymes have been highlighted in basic research, industry, and translational medicine as a new cutting-edge tool. In this work, and for the first time, we disclose a tumor alleviation property of a nanozyme that is made up of amine-terminated sixth-generation polyamidoamine dendrimers with encapsulated tiny platinum nanoparticles. We systematically conducted the synthesis and characterization of the dendrimer-encapsulated Pt nanoparticles (denoted Pt-dendrimer) and confirmed their enzymatic function (hydrogen peroxide (H2O2) decomposition) within various cell lines (normal, cancerous), including glioblastoma (GBM) cells. By understanding the effects of the Pt-dendrimer at the gene level, especially related to cancer cell metastasis, we have thoroughly demonstrated its ability for tumor alleviation and suppressing GBM migration, invasion, and adhesion. The present findings show great promise for the application of the nanozyme for use in GBM-related basic research as well as at clinical sites.

A Review on Metal- and Metal Oxide-Based Nanozymes: Properties, Mechanisms, and Applications

Since the ferromagnetic (Fe3O4) nanoparticles were firstly reported to exert enzyme-like activity in 2007, extensive research progress in nanozymes has been made with deep investigation of diverse nanozymes and rapid development of related nanotechnologies. As promising alternatives for natural enzymes, nanozymes have broadened the way toward clinical medicine, food safety, environmental monitoring, and chemical production. The past decade has witnessed the rapid development of metal- and metal oxide-based nanozymes owing to their remarkable physicochemical properties in parallel with low cost, high stability, and easy storage. It is widely known that the deep study of catalytic activities and mechanism sheds significant influence on the applications of nanozymes. This review digs into the characteristics and intrinsic properties of metal- and metal oxide-based nanozymes, especially emphasizing their catalytic mechanism and recent applications in biological analysis, relieving inflammation, antibacterial, and cancer therapy. We also conclude the present challenges and provide insights into the future research of nanozymes constituted of metal and metal oxide nanomaterials.

Micro-Bio-Chemo-Mechanical-Systems: Micromotors, Microfluidics, and Nanozymes for Biomedical Applications

Wireless nano-/micromotors powered by chemical reactions and/or external fields generate motive forces, perform tasks, and significantly extend short-range dynamic responses of passive biomedical microcarriers. However, before micromotors can be translated into clinical use, several major problems, including the biocompatibility of materials, the toxicity of chemical fuels, and deep tissue imaging methods, must be solved. Nanomaterials with enzyme-like characteristics (e.g., catalase, oxidase, peroxidase, superoxide dismutase), that is, nanozymes, can significantly expand the scope of micromotors' chemical fuels. A convergence of nanozymes, micromotors, and microfluidics can lead to a paradigm shift in the fabrication of multifunctional micromotors in reasonable quantities, encapsulation of desired subsystems, and engineering of FDA-approved core-shell structures with tuneable biological, physical, chemical, and mechanical properties. Microfluidic methods are used to prepare stable bubbles/microbubbles and capsules integrating ultrasound, optoacoustic, fluorescent, and magnetic resonance imaging modalities. The aim here is to discuss an interdisciplinary approach of three independent emerging topics: micromotors, nanozymes, and microfluidics to creatively: 1) embrace new ideas, 2) think across boundaries, and 3) solve problems whose solutions are beyond the scope of a single discipline toward the development of micro-bio-chemo-mechanical-systems for diverse bioapplications.

Temperature-responsive iron nanozymes based on poly(N-vinylcaprolactam) with multi-enzyme activity

Iron (Fe)-based nanozymes are widely applied in the biomedical field due to their enzyme-like catalytic activity. Herein, Fe(ii)-based coordination polymer nanohydrogels (FeCPNGs) have been conveniently prepared as a new type of nanozyme by the chelation reaction between ferrous iron and polymer nanohydrogels. The P(VCL-co-NMAM) nanohydrogels prepared by a reflux precipitation polymerization method using N-vinylcaprolactam (VCL) and N-methylol acrylamide (NMAM) as monomers and N,N-methylenebisacrylamide (MBA) as a crosslinker were esterified using P2O5 and then chelated with Fe(ii) ions to form nanozymes with peroxidase and superoxide dismutase (SOD) activity. It was found by dynamic light scattering (DLS) and transmission electron microscopy (TEM) that the nanohydrogels prepared with a monomer concentration of 4% and mass ratio of 1 : 1 (VCL : NMAM) had more uniform particle size, better dispersion and a distinct temperature response. The results of Fourier transform infrared (FTIR), DLS, TEM, X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) indicated the successful preparation of the esterified nanohydrogel and FeCPNGs. Of particular importance is that such FeCPNGs can functionally mimic two antioxidant enzymes (peroxidase and superoxide dismutase) by UV analysis of catalytic oxidation between 3,3,5,5-tetramethylbenzidine (TMB) and H2O2 and the kit analysis of SOD-like activity.