Academic literature on the topic 'Nanozyme activity'

The nanozyme-strip is a novel POCT technology which is different from the conventional colloidal gold strip. It primarily utilizes the catalytic activity of nanozyme to achieve a high-sensitivity detection of target by amplifying the detection signal. However, previous research has chiefly focused on optimizing nanozyme-strip from the perspective of increasing nanozyme activity, little is known about other physicochemical factors. In this work, three sizes of Fe3O4 nanozyme and three sizes of CoFe2O4 nanozyme were used to investigate the key factors of nanozyme-strip for optimizing and improving its detection performance. We found that three sizes of Fe3O4 nanozyme all gather at the bottom of the nitrocellulose (NC) membrane, and three sizes of CoFe2O4 nanozyme migrate smoothly on the NC membrane, respectively. After color development, the surface of NC membranes distributed with CoFe2O4 peroxidase nanozymes had significant color change. Experimental results show that CoFe2O4 nanozymes had better dispersity than Fe3O4 nanozymes in an aqueous solution. We observed that CoFe2O4 nanozymes with smaller particle size migrated to the middle of the NC membrane with a higher number of particles. According to the results above, 55 ± 6 nm CoFe2O4 nanozyme was selected to prepare the nanozyme probe and achieved a highly sensitive detection of Aβ42Os on the nanozyme-strip. These results suggest that nanozyme should be comprehensively evaluated in its dispersity, the migration on NC membrane, and the peroxidase-like activity to determine whether it can be applied to nanozyme-strip.

As one of the nanostructures with enzyme-like activity, nanozymes have recently attracted extensive attention for their biomedical applications, especially for bacterial disinfection treatment. Nanozymes with high peroxidase activity are considered to be excellent candidates for building bacterial disinfection systems (nanozyme-H2O2), in which the nanozyme will promote the generation of ROS to kill bacteria based on the decomposition of H2O2. According to this criterion, a cerium oxide nanoparticle (Nanoceria, CeO2, a classical nanozyme with high peroxidase activity)-based nanozyme-H2O2 system would be very efficient for bacterial disinfection. However, CeO2 is a nanozyme with multiple enzyme-like activities. In addition to high peroxidase activity, CeO2 nanozymes also possess high superoxide dismutase activity and antioxidant activity, which can act as a ROS scavenger. Considering the fact that CeO2 nanozymes have both the activity to promote ROS production and the opposite activity for ROS scavenging, it is worth exploring which activity will play the dominating role in the CeO2-H2O2 system, as well as whether it will protect bacteria or produce an antibacterial effect. In this work, we focused on this discussion to unveil the role of CeO2 in the CeO2-H2O2 system, so that it can provide valuable knowledge for the design of a nanozyme-H2O2-based antibacterial system.

Food safety issues are a worldwide concern. Pathogens, toxins, pesticides, veterinary drugs, heavy metals, and illegal additives are frequently reported to contaminate food and pose a serious threat to human health. Conventional detection methods have difficulties fulfilling the requirements for food development in a modern society. Therefore, novel rapid detection methods are urgently needed for on-site and rapid screening of massive food samples. Due to the extraordinary properties of nanozymes and aptamers, biosensors composed of both of them provide considerable advantages in analytical performances, including sensitivity, specificity, repeatability, and accuracy. They are considered a promising complementary detection method on top of conventional ones for the rapid and accurate detection of food contaminants. In recent years, we have witnessed a flourishing of analytical strategies based on aptamers and nanozymes for the detection of food contaminants, especially novel detection models based on the regulation by single-stranded DNA (ssDNA) of nanozyme activity. However, the applications of nanozyme-based aptasensors in food safety are seldom reviewed. Thus, this paper aims to provide a comprehensive review on nanozyme-based aptasensors in food safety, which are arranged according to the different interaction modes of ssDNA and nanozymes: aptasensors based on nanozyme activity either inhibited or enhanced by ssDNA, nanozymes as signal tags, and other methods. Before introducing the nanozyme-based aptasensors, the regulation by ssDNA of nanozyme activity via diverse factors is discussed systematically for precisely tailoring nanozyme activity in biosensors. Furthermore, current challenges are emphasized, and future perspectives are discussed.

Nanozymes are nanomaterial with natural enzyme-like activity and can catalyze specific reactions for analyte identification and detection. Compared to natural enzymes, they have several benefits, including being steady, low-cost, easy to prepare and store. Based on the promising development of nanozymes in surface-enhanced Raman scattering (SERS), this paper reviews the classification of different types of nanozymes in SERS, including metal-based nanozyme, carbon-based nanozyme, metal-organic framework (MOF)/covalent organic framework (COF)-based nanozyme, and semiconductor-based nanozyme, followed by a detailed overview of their SERS applications in disease diagnosis, food safety, and environmental safety. Finally, this paper discusses the practical shortcomings of nanozymes in SERS applications and makes some suggestions for further research.

Nanozymes have the potential to replace natural enzymes, so they are widely used in energy conversion technologies such as biosensors and signal transduction (converting biological signals of a target into optical, electrical, or metabolic signals). The participation of nucleic acids leads nanozymes to produce richer interface effects and gives energy conversion events more attractive characteristics, creating what are called “functional nanozymes”. Since different nanozymes have different internal structures and external morphological characteristics, functional modulation needs to be compatible with these properties, and attention needs to be paid to the influence of nucleic acids on nanozyme activity. In this review, “functional nanozymes” are divided into three categories, (nanozyme precursor ion)/ (nucleic acid) self-assembly, nanozyme-nucleic acid irreversible binding, and nanozyme-nucleic acid reversible binding, and the effects of nucleic acids on modulation principles are summarized. Then, the latest developments of nucleic acid-modulated nanozymes are reviewed in terms of their use in energy conversion technology, and their conversion mechanisms are critically discussed. Finally, we outline the advantages and limitations of “functional nanozymes” and discuss the future development prospects and challenges in this field.

To inhibit the growth of bacteria, the DA-PPI nanozyme with enhanced peroxidase-like activity was synthesized. The DA-PPI nanozyme was obtained by depositing high-affinity element iridium (Ir) on the surface of Pd-Pt dendritic structures. The morphology and composition of DA-PPI nanozyme were characterized using SEM, TEM, and XPS. The kinetic results showed that the DA-PPI nanozyme possessed a higher peroxidase-like activity than that of Pd-Pt dendritic structures. The PL, ESR, and DFT were employed to explain the high peroxidase activity. As a proof of concept, the DA-PPI nanozyme could effectively inhibit E. coli (G−) and S. aureus (G+) due to its high peroxidase-like activity. The study provides a new idea for the design of high active nanozymes and their application in the field of antibacterial.

The current review is devoted to nanozymes, i.e., nanostructured artificial enzymes which mimic the catalytic properties of natural enzymes. Use of the term “nanozyme” in the literature as indicating an enzyme is not always justified. For example, it is used inappropriately for nanomaterials bound with electrodes that possess catalytic activity only when applying an electric potential. If the enzyme-like activity of such a material is not proven in solution (without applying the potential), such a catalyst should be named an “electronanocatalyst”, not a nanozyme. This paper presents a review of the classification of the nanozymes, their advantages vs. natural enzymes, and potential practical applications. Special attention is paid to nanozyme synthesis methods (hydrothermal and solvothermal, chemical reduction, sol-gel method, co-precipitation, polymerization/polycondensation, electrochemical deposition). The catalytic performance of nanozymes is characterized, a critical point of view on catalytic parameters of nanozymes described in scientific papers is presented and typical mistakes are analyzed. The central part of the review relates to characterization of nanozymes which mimic natural enzymes with analytical importance (“nanoperoxidase”, “nanooxidases”, “nanolaccase”) and their use in the construction of electro-chemical (bio)sensors (“nanosensors”).

Developing efficient laccase-mimicking nanozymes via a facile and sustainable strategy is intriguing in environmental sensing and fuel cells. In our work, a MnO/porous carbon (MnO/PC) nanohybrid based on fungus was synthesized via a facile carbonization route. The nanohybrid was found to possess excellent laccase-mimicking activity using 2,2′-azinobis (3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS) as the substrate. Compared with the natural laccase and reported nanozymes, the MnO/PC nanozyme had much lower Km value. Furthermore, the electrochemical results show that the MnO/PC nanozyme had high electrocatalytic activity toward the oxygen reduction reaction (ORR) when it was modified on the electrode. The hybrid nanozyme could catalyze the four-electron ORR, similar to natural laccase. Moreover, hydroquinone (HQ) induced the reduction of oxABTS and caused the green color to fade, which provided colorimetric detection of HQ. A desirable linear relationship (0–50 μM) and detection limit (0.5 μM) were obtained. Our work opens a simple and sustainable avenue to develop a carbon–metal hybrid nanozyme in environment and energy applications.

Compared with natural enzymes, nanozymes have the advantages of good catalytic performance, high stability, low cost, and can be used under extreme conditions. Preparation of highly active nanozymes through simple methods and their application in bioanalysis is highly desirable. In this work, a nanozyme based on dispersion of hemin by graphene quantum dot (GQD) is demonstrated, which enables colorimetric detection of glutathione (GSH). GQD was prepared by a one-step hydrothermal synthesis method. Hemin, the catalytic center of heme protein but with low solubility and easy aggregation that limits its catalytic activity, can be dispersed with GQD by simple sonication. The as-prepared Hemin/GQD nanocomplex had excellent peroxidase-like activity and can be applied as a nanozyme. In comparison with natural horseradish peroxidase (HRP), Hemin/GQD nanozyme exhibited a clearly reduced Michaelis–Menten constant (Km) when tetramethylbenzidine (TMB) was used as the substrate. With H2O2 being the substrate, Hemin/GQD nanozyme exhibited a higher maximum reaction rate (Vmax) than HRP. The mechanisms underlying the nanozyme activity were investigated through a free radical trapping experiment. A colorimetric platform capable of sensitive detection of GSH was developed as the proof-of-concept demonstration. The linear detection range was from 1 μM to 50 μM with a low limit of detection of 200 nM (S/N = 3). Determination of GSH in serum samples was also achieved.

Facile construction of functional nanomaterials with laccase-like activity is important in sustainable chemistry since laccase is featured as an efficient and promising catalyst especially for phenolic degradation but still has the challenges of high cost, low activity, poor stability and unsatisfied recyclability. In this paper, we report a simple method to synthesize nanozymes with enhanced laccase-like activity by the self-assembly of copper ions with various imidazole derivatives. In the case of 1-methylimidazole as the ligand, the as-synthesized nanozyme (denoted as Cu-MIM) has the highest yield and best activity among the nanozymes prepared. Compared to laccase, the Km of Cu-MIM nanozyme to phenol is much lower, and the vmax is 6.8 times higher. In addition, Cu-MIM maintains excellent stability in a variety of harsh environments, such as high pH, high temperature, high salt concentration, organic solvents and long-term storage. Based on the Cu-MIM nanozyme, we established a method for quantitatively detecting phenol concentration through a smartphone, which is believed to have important applications in environmental protection, pollutant detection and other fields.

In the present thesis, entitled “Strategies for the modulation of catalytic activity of Zn(II)-based of artificial nucleases”, the results obtained in an extensive investigation on the reactivity of different catalytic systems for hydrolytic cleavage of phosphate diesters are reported. Phosphate diesters have a remarkable importance since they constituted the backbone of essential biomolecules as DNA and RNA. Indeed, the high stability of those polianions towards the hydrolytic attack is due to the presence of the phosphodiester group. On the other hand, the hydrolytic cleavage of nucleic acids occurs in living organism is few milliseconds, thanks to nucleases which are the enzyme devoted to this task. In the attempt to reproduce the activity of such enzymes, which are among the most efficient present in nature, I focused my attention on the design and synthesis of catalytic agents based on metal ions, namely Zn(II) ions, and studying their reactivity towards a RNA model, the 2-hydroxypropyl-para-nitrophenyl phosphate (HPNP). In the first part of the thesis, the interesting results I obtained in the study of the reactivity of monometallic Zn(II)-based complexes towards HPNP are reported. The Zn(II) complexes used in this studied were 1 (mononuclear complex of 1,4,7-triazacyclononane, TACN) and 2, (mononuclear complex of 1,4,7-trimethyl-1,4,7-triazacyclononane, TMTACN) which is the corresponding permethylated derivative. I will show how the small differences in the structure of the two ligands affect the HPNP cleavage reaction with effects never reported before. The hypothesis that such differences may arise from different coordination geometries of the metal will be discussed. The second part of the thesis is focused on the investigation of the effects that the local environment surrounding the metal complexes produces on their reactivity towards phosphodiester cleavage. In this view, I designed supramolecular systems based on functionalized gold nanoparticles. Such catalytic gold nanoparticles, known as nanozymes, were obtained by coating them with thiols bearing the a catalytic unit, namely the Zn(II) complex of the ligand TACN. Microenvironment modulation was obtained by changing the spacer between the catalytic unit and the anchoring part (thiol moiety). I will show that the increase the length of the alky spacer from four carbon atoms (thiol 1) to twelve atoms (thiol 4) strongly increases the nanozyme reactivity towards the hydrolytic cleavage of HPNP. On the other hand, longer but more polar oligo(ethyleneoxide) spacer in 3 does not have any effect on the nanozyme reactivity. The experiments reported will demonstrate that such a reactivity modulation depends on an enthalpy-driven stabilization of the transition state of the reaction and is strongly correlated to the polarity of the microenvironment, presumably the interface between the particle coating monolayer and the bulk water solution, where the reaction occurs. Finally, in the last part of the present thesis, I shall report the results obtained by studying how the morphology of the gold nanoparticles-coating monolayer affects the reactivity of the nanozymes. Therefore, I prepared mixed-monolayer nanoparticles where the coating contains simultaneously thiol 1 and the zwitterionic thiol (ZW), which bears a phosphorylcholine moiety, or the triethilenglycol-thiol (TEG, in different ratios). The main function of the latter is to improve water solubility to the nanozymes, but I reasoned that they could have an effect on the reciprocal organization and sorting of the molecules in the monolayer. Indeed, preliminary experiments performed demonstrated that different distributions of the catalytic units in the nanoparticles surface, either in patches or random, were obtained when the two different inert thiols were used. Interestingly, such different distributions affect the substrate affinity of the catalytic system but not its activity. In conclusion, we have performed a systematic approach to study of how the reactivity of Zn(II) ions in hydrolytic phosphate-cleaving catalysts can be modulated using different strategies, ranging to the modification of the ligand structure to the control of the local microenvironment or of the catalyst reciprocal proximity using monolayer protected nanoparticles.
Questa tesi di dottorato riassume i risultati che ho ottenuto cimentandomi in un progetto di ricerca il cui obiettivo era l’individuazione di nuove strategie capaci di aumentare l’efficacia dei catalizzatori per l’idrolisi di diesteri fosforici. Questi catalizzatori, noti nella letteratura scientifica con il nome di “nucleasi artificiali”, erano nel mio caso costruiti a partire da complessi dello ione Zn(II) con leganti poliamminci. La struttura dei complessi utilizzati ha spaziato da piccoli sitemi mononucleari a complessi sistemi catalitici supramolecolari basati su nanoparticelle di oro (nanozimi). I diesteri fosforici sono di vitale importanza nella chimica biologica visto che formano parte dello scheletro di biomolecole essenziali come il DNA e il RNA. Queste macromolecole sono caratterizzate da un’alta stabilità contro la scissione idrolitica, utilie per garantire la preservazione dell’informazione genetica, che è dovuta proprio alla presenza dei residui fosfato. D’altra parte, l’idrolisi dei gruppi fosfodiesterei di DNA e RNA avviene negli organismi viventi in pochi millisecondi, grazie alle nucleasi, gli enzimi idrolitici preposti a questa reazione. Il nostro interesse è quello di riprodurre l’attività di questi enzimi con sistemi di origine sintetica. In particolari, siamo convinti che il miglior candidato per costituire il nucleo “attivo” di sistemi idrolitici artificiali sia lo ione Zn(II). Conseguentemente abbiamo preparato una serie di complessi di Zn(II) caratterizzati da strutture e filosofie di assemblaggio anche molto diverse e ne abbiamo studiato la reattività nel promuovere la scissione idrolitica di un modello di RNA, il 2-idrossipropil-p-nitrofenil fosfato (HPNP). Nella prima parte della tesi sono discussi gli interessanti risultato che ho ottenuto nello strudio della reattività di complessi monometallici di Zn(II) nella idrolisi dell’HPNP. I complessi studiati sono riportati in figura e sono semplici complessi monucleari dei leganti 1,4,7-triazaciclononano(TACN) e 1,4,7-trimetil-1,4,7-triazaciclononano (TMTACN). Gli studi effettuati dimostrano come le piccole differenze nella struttura dei due leganti portano a notevoli differenze nella reattività dei complessi. Nel corso della discussione sarà suggerito che tali effetti, mai descritti in precedenza, possano essere dovuti a diverse geometrie di coordinazione dello ione metallico. Nella seconda parte della tesi mi sono dedicata a studiare gli effetti prodotti dall’ambiente locale in cui i complessi vengono a trovarsi sulla loro reattività come catalizzatori della scissione idrolitica di esteri fosforici. In quest’ottica, ho progettato una serie di sistemi supramolecolari basati su nanoparticelle d’oro funzionalizzate. Queste nanoparticelle catalitiche, conosciute come nanozimi, sono state ottenute ricoprendo i nuclei di oro con tioli dotati di un gruppo reattivo, in particolare di un complesso di Zn(II) del legante TACN. La modulazione del microambiente di reazione è stata ottenuta modificando la struttura dei tioli utilizzati, ed in particolare lo spaziatore inserito tra l’unità catalitica ed il gruppo tiolo preposto all’ancoraggio alla superficie d’oro- I risultati riportati dimostreranno che l’aumento della lunghezza dello spaziatore da quattro atomi di carbonio (tiolo 1) a dodici atomi (tiolo 4) produce un notevole aumento della reattività di questi nanozimi nell’idrolizzare l’HPNP. D’altra parte, l’inserimento di uno spaziatore di tipo oligo(ossietilenica) (tiolo 3), più lungo ma anche più polare, non comporta alcun vantaggio in termini di reattività. La modulazione di reattività osservata dipende, secondo gli studi effettuati, da una miglior stabilizzazione, dovuta ad effetti di natura entalpica, dello stato di transizione della reazione. Tale stabilizzazione è fortemente correlata alla polarità locale del microambiente di reazione, presumibilmente l’interfaccia tra il monostrato e la soluzione acquosa. Nell’ultima parte della tesi descriverò i risultati ottenuti studiando come la morfologia dello strato che ricopre le nanoparticelle d’oro influenzi la reattività dei nanozimi. In questa prospettiva, ho preparato nanoparticelle di oro (2 nm il diametro del nocciolo metallico) coperte in proporzioni diverse con monostrati misti composti dal tiolo 1 ed da un tiolo dotato di un gruppo fosfoilcolina (ZW) o di un residuo di trietileneglicole (TEG). La funzione primaria di questi ultimi tioli è apportare solubilità acquosa al nanosistema ma mi era sembrato possibile che essi potessero anche influenzare la disposizione delle unità catalitiche sulla particella. In effetti, gli esperimenti effettuati in via preliminare mostrano che l’uso dei due tioli porta a diverse distribuzioni delle molecole di ricoprimento che si dispongono in modo casuale o formando “isole”. Queste diverse distribuzioni influenzano l’affinità dei nanozimi per il substrato HPNP ma non la sua attività idrolitica. In conclusione, in questa tesi ho descritto i risultati ottenuti nell’effettuare uno studio simultaneo e sistematico di diverse possibili strategie capaci di modulare la reattività di agenti idrolitici artificiali basati sullo ione zinco(II). I risultati ottenuti potranno aprire la strada a nuovi sviluppi capaci di portare alla realizzazione di sistemi dotati di efficacia realmente comparabile a quella degli enzimi.

In recent years carbon-based nanomaterials are growing rapidly in the field of science and technology, due to the tunable optical and physical properties such as electronic arrangement, photostability, flexibility and excellent biocompatibility. Considering, the emerging materials of carbon family such as graphene, graphene oxide (GO) and it derivative, carbon nanotube, fullerene, covalent organic framework (COF) carbon nitride (g-C3N4) and carbon dots (C-Dots) has been highlighted. Based on their structure and morphology, the carbon-based materials have received immense interest in the fields of catalysis, electronic, photonic devices, sensors, molecular recognition and biomedical applications. At the same time, it is also reported that the tunable size and shape of the materials (extended -conjugation, state of oxidation etc.) has shown significant attention in antibacterial activity, relative molar extinction coefficient and cellular internalization, molecular recognition etc. Hence this chapter has shortly provided the literature background of preparation and applications of carbon-based materials. Further information regarding synthesis of different type of carbon and sulfur-based luminescent materials and their functionalization are reported in the literature. Finally, a stack of literature reports towards the materials and biological applications such as biomolecular recognition, cellular imaging, sensing and stimuli responsive systems.

Infectious diseases caused by pathogenic bacteria are creating a global health problem. In the recent report of World Health Organization (WHO), it has been mentioned that around 7 lacks people are dying each year worldwide due to drug resistant microbials. After discovery of the lifesaving “wonder drug” molecule penicillin, it was extensively used for the treatment of bacterial infection diseases. However, the excessive use of antibiotics leads to the development of antimicrobial resistance in the pathogenic bacterial strains to overcome the bactericidal effect of antibiotics. The drug-resistance bacteria follow multiple pathways to show resistance towards the existing antimicrobial agents and eventually make them abortive. The prevalence of these drug resistant bacterial strains poses a serious threat to the present medical system. Therefore, there is an urgency to develop advanced antimicrobial agents which can restrict the spread of pathogenic bacteria to eradicate infectious diseases. In this context, the current advancement in the field of nanotechnology would help us to develop nanomaterial-based antimicrobial agents which could be one of the possible alternatives of conventionally used antibiotics. There are numerous reports, which established that nanomaterials such as graphene oxide, carbon nanotube, noble metal nanoparticles, metal oxides like ZnO2, MnO2 etc. have possessed antibacterial activity. In particular, the use of nanosized molybdenum disulfide (MoS2), a transition metal dichalcogenide showed a great potential to utilize for the development of potent antibacterial agents owing to its unique chemical and photophysical properties. Two-dimensional MoS2 nanosheets provide a large surface to volume ratio for the effective interaction with the bacterial cell membrane. For better biological interactions of MoS2 nanomaterials, its surface modification can be easily achieved through functionalization using thiol ligand molecule. Functionalization also enhances its aqueous dispersibility in manyfold. In this thesis work, I have utilized MoS2 nanomaterials and their nanocomposites to develop nanomaterial-based effective antimicrobial agents for the pathogenic bacterial strains using multiple strategies. To extend my work towards the development of nanomaterial-based antibacterial agents, I have explored antibacterial activity of the supramolecularly self-assembled nanosized cage molecule to eradicate drug-resistant bacteria. Apart from antibacterial activity, I have also expanded the scope of applicability of our newly developed nanomaterials in the direction of bio-analyte detection and environmental remediation such as degradation of organic pollutant and detoxification of the chemical warfare agent.

AbstractNeurodegenerative diseases are incurable diseases that get worse as time passes. These diseases are very heterogeneous in nature but have common characteristics like abnormal deposition of protein, glycation, inflammation in particular areas of the brain, and progressive neuronal loss due to oxidative stress. Among these, oxidative stress alone causes a high level of degeneration of neurons. To reduce oxidative stress, natural antioxidants are used but they have some drawbacks like instability, high cost and low reusability. To overcome this, nanozymes are introduced and we have emphasized on major nanozymes whose antioxidant capability has been proven which are gold nanozymes, fullerene, nanoceria, and quantum dots. Gold nanoparticles and their conjugates with other molecules can mimic the enzymatic activity of superoxide dismutase and catalase which decrease the amount of hydrogen peroxide and superoxide radicals in cells. Gold Nanozyme treatment reduces the oxidative stress, nitrite, and sulfhydryl levels in the brain and also rectifies the superoxide dismutase, glutathione, and catalase activity levels. Fullerenols has shown superoxide dismutase activity which was 268 times more effective than mannitol and 37 times more effective than Vitamin E for lipid radicals. Nanoceria has the ability to mimic Superoxide Dismutase as well as catalase activity, can also detoxify peroxynitrite. Quantum dots (QDs) like Graphene Oxide QDs can scavenge the reactive oxygen species and also show indirect activity which alleviates the pathogenesis of the disease. Thus, a nanozyme can be used as an efficient nanomedicine if it is tailored to possess high catalytic activity while eliminating all complications.

Iron oxide nanoparticles perform biological activity under physiological conditions. They exhibit enzyme-like properties that catalyze redox reactions mediated by natural enzymes of oxidoreductase and are classified into a typical of nanozymes that are defined as nanomaterials with enzyme-like activities. In addition, iron oxide nanoparticles widely exist in biological system, such as magnetosome and ferritin that not only regulate iron metabolism, but also regulate ROS homostasis. The enzyme-like properties of iron oxide nanoparticles render them with broad biomedical applications including immunoassay, biosensor, antimicrobial, anti-tumor, antioxidant. Taken together, iron oxide nanoparticles are bioactive materials and may perform particular biological function in life activity.

Natural enzymes perform pivotal role in all biological reactions in living things. But their practical operations are restricted due to difficulty in synthesis, reprocessing, cost, and easy denaturation. To combat these hurdles, blistering exertion is dedicated for improving these enzymes to other enzymes known “artificial enzymes.” The man-made enzymes, which possess enzyme mimicking properties, have fascinated researchers’ attentions. From last decade, nanozymes have attained tremendous progression. Nanomaterials-based enzyme elucidates expressive features like distinct preparative protocols, low cost, long duration for storage, and high stability towards environment than natural enzymes. This draft carries survey on 1) nanozymes literature, which is considerably explored by a diverse class of nanocomposites such as composites of halogens, carbon-based nanostructured materials etc.; 2) the recent progresses made in the fabrication of nanozymes for enzyme mimicking activity; 3) the mechanism of action, schemes to increase enzymatic activities, catalytic property and recent trends of using nanomaterials-based enzymes in the food industries.

From the last two decades the world has progressed enormously to upgrade the wellbeing of humans by revamping the disease diagnostic and treatment. To accomplish this task, the nano-biotechnology has significantly aided in the complete transformation of disease treatment. Nanomaterials have been of great interest for better drug delivery, due to their significant catalytic activities, feasibility, and reduced production cost. Moreover, the implementation of enzyme like properties, to increase better drug delivery has gained enormous attention. Modification of the nano-scaled materials to nanozymes and enzyme-responsive nanoparticles is considered as revolutionary concept in the field of theragnostic. This chapter elaborates the diversified range of nano-material based enzymes, their synthesis methods, modification strategies, and factors influencing the catalytic activity of these enzymes. Therapeutic applications of nano-material based enzymes and their limitations have also been discussed.