Single amino acid bionanozyme for environmental remediation

Cu-chelated polydopamine nanozymes with laccase-like activity for photothermal catalytic degradation of dyes

The industrial applications of enzymes are usually hindered by the high production cost, intricate reusability, and low stability in terms of thermal, pH, salt, and storage. Therefore, the de novo design of nanozymes that possess the enzyme mimicking biocatalytic functions sheds new light on this field. Here, we propose a facile one-pot synthesis approach to construct Cu-chelated polydopamine nanozymes (PDA-Cu NPs) that can not only catalyze the chromogenic reaction of 2,4-dichlorophenol (2,4-DP) and 4-aminoantipyrine (4-AP), but also present enhanced photothermal catalytic degradation for typical textile dyes. Compared with natural laccase, the designed mimic has higher affinity to the substrate of 2,4-DP with Km of 0.13 mM. Interestingly, PDA-Cu nanoparticles are stable under extreme conditions (temperature, ionic strength, storage), are reusable for 6 cycles with 97 % activity, and exhibit superior substrate universality. Furthermore, PDA-Cu nanozymes show a remarkable acceleration of the catalytic degradation of dyes, malachite green (MG) and methylene blue (MB), under near-infrared (NIR) laser irradiation. These findings offer a promising paradigm on developing novel nanozymes for biomedicine, catalysis, and environmental engineering.

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.

Ring-opening polymerization of lactide catalyzed using metal-coordinated enzyme-like amino acid assemblies

Polylactide (PLA), a biocompatible and biodegradable polymer, is widely used in diverse biomedical applications. However, the industry standard for converting lactide into PLA involves toxic tin (Sn)-based catalysts. To mitigate the use of these harmful catalysts, other environmentally benign metal-containing agents for efficient lactide polymerization have been studied, but these alternatives are hindered by complex synthesis processes, reactivity issues, and selectivity limitations. To overcome these shortcomings, we explored the catalytic activity of Cu-(Phe)2 and Zn-(Phe)2 metal-amino acid co-assemblies as potential catalysts of the ring-opening polymerization (ROP) of lactide into PLA. Catalytic activity of the assemblies was monitored at different temperatures and solvents using 1H-NMR spectroscopy to determine the catalytic parameters. Notably, Zn-(Phe)2 achieved >99% conversion of lactide to PLA within 12 h in toluene under reflux conditions and was found to have first-order kinetics, whereas Cu-(Phe)2 exhibited significantly lower catalytic activity. Following Zn-(Phe)2-mediated catalysis, the resulting PLA had an average molecular weight of 128 kDa and a dispersity index of 1.25 as determined by gel permeation chromatography. Taken together, our minimalistic approach expands the realm of metal-amino acid-based supramolecular catalytic nanomaterials useful in the ROP of lactide. This advancement shows promise for the future design of simplified biocatalysts in both industrial and biomedical applications.

Unveiling the role of inorganic nanoparticles in Earth's biochemical evolution through electron transfer dynamics

This article explores the intricate interplay between inorganic nanoparticles and Earth's biochemical history, with a focus on their electron transfer properties. It reveals how iron oxide and sulfide nanoparticles, as examples of inorganic nanoparticles, exhibit oxidoreductase activity similar to proteins. Termed "life fossil oxidoreductases," these inorganic enzymes influence redox reactions, detoxification processes, and nutrient cycling in early Earth environments. By emphasizing the structural configuration of nanoparticles and their electron conformation, including oxygen defects and metal vacancies, especially electron hopping, the article provides a foundation for understanding inorganic enzyme mechanisms. This approach, rooted in physics, underscores that life's origin and evolution are governed by electron transfer principles within the framework of chemical equilibrium. Today, these nanoparticles serve as vital biocatalysts in natural ecosystems, participating in critical reactions for ecosystem health. The research highlights their enduring impact on Earth's history, shaping ecosystems and interacting with protein metal centers through shared electron transfer dynamics, offering insights into early life processes and adaptations.

Computation-Driven Rational Design of Self-Assembled Short Peptides for Catalytic Hydrogen Production

Self-assembling peptides represent a captivating area of study in nanotechnology and biomaterials. This interest is largely driven by their unique properties and the vast application potential across various fields such as catalytic functions. However, design complexities, including high-dimensional sequence space and structural diversity, pose significant challenges in the study of such systems. In this work, we explored the possibility of self-assembled peptides to catalyze the hydrolysis of hydrosilane for hydrogen production using ab initio calculations and carried out wet-lab experiments to confirm the feasibility of these catalytic reactions under ambient conditions. Further, we delved into the nuanced interplay between sequence, structural conformation, and catalytic activity by combining modeling with experimental techniques such as transmission electron microscopy and nuclear magnetic resonance and proposed a dual mode of the microstructure of the catalytic center. Our results reveal that although research in this area is still at an early stage, the development of self-assembled peptide catalysts for hydrogen production has the potential to provide a more sustainable and efficient alternative to conventional hydrogen production methods. In addition, this work also demonstrates that a computation-driven rational design supplemented by experimental validation is an effective protocol for conducting research on functional self-assembled peptides.

Nanozyme-integrated alcogel colorimetric sensor for rapid and on-site detection of tert-butyl hydroquinone

Tert-butyl hydroquinone (TBHQ) stand as one of the most widely used antioxidants in food and daily chemical products. Rapid and sensitive monitoring of TBHQ holds considerable importance in safeguarding human health due to its potential risks. In this study, we devised an alcogel-based colorimetric sensor enabling the portable and visual detection of TBHQ. The Ce-UiO-66 nanozyme exhibiting remarkable oxidase-like activity, was synthesized and characterized, facilitating the catalysis of TBHQ oxidation to 2-tert-butyl-1,4-benzoquinone (TBBQ). The ensuing chromogenic reaction between TBBQ and ethylenediamine produced a stable and colored product, serving as a reliable indicator for the rapid and specific detection of TBHQ. Building upon this discovery, a portable and low-cost colorimetric sensor was fashioned by integrating the nanozyme into κ-carrageenan alcogel, thereby enabling on-site TBHQ detection via a smartphone-based sensing platform. The colorimetric sensor exhibited a detection limit of 0.8 μg mL-1, demonstrating robust performance across various matrices such as edible oils, cosmetics, and surface water. Recoveries ranged from 84.9 to 95.5%, with the sensor's accuracy further validated through gas chromatography-mass spectrometry. Our study presents an effective approach to rapid and convenient monitoring of TBHQ, exhibiting good extensibility and practicability.

Rapid and Green Fabrication of Nanozyme with Geminal CuN3O Configuration for Efficient Catecholase-Mimicking

Fabrication of nanozyme with catecholase-like catalytic activity faces the great challenge of merging outstanding activity with low cost as well as simple, rapid, and low-energy-consumed production, restricting its industrial applications. Herein, an inexpensive yet robust nanozyme (i.e., DT-Cu) via simple one-step coordination between diaminotriazole (DT) and CuSO4 within 1 h in water at room temperature is constructed. The asymmetric dicopper site with CuN3O configuration for each copper as well as Cu─O bond length of ≈1.83 Å and Cu···Cu distance of ≈3.5 Å in DT-Cu resemble those in catechol oxidase (CO), which ensure its prominent intrinsic activity, outperforming most CO-mimicking nanozymes and artificial homogeneous catalysts. The use of inexpensive DT/CuSO4 in this one-pot strategy endows DT-Cu with only ≈20% cost of natural CO per activity unit. During catalysis, O2 experienced a 4e-dominated reduction process accompanied by the formation of 1O2 and H2O2 intermediates and the product of H2O. Benefiting from the low cost as well as the distinctive structure and superior intrinsic activity, DT-Cu presents potential applications ranging from biocatalysis to analytical detection of biomolecules such as epinephrine and beyond.

A Bioinspired Single-Atom Fe Nanozyme with Excellent Laccase-Like Activity for Efficient Aflatoxin B1 Removal

The applications of natural laccases are greatly restricted because of their drawbacks like poor biostability, high costs, and low recovery efficiency. M/NC single atom nanozymes (M/NC SAzymes) are presenting as great substitutes due to their superior enzyme-like activity, excellent selectivity and high stability. In this work, inspired by the catalytic active center of natural enzyme, a biomimetic Fe/NC SAzyme (Fe-SAzyme) with O2-Fe-N4 coordination is successfully developed, exhibiting excellent laccase-like activity. Compared with their natural counterpart, Fe-SAzyme has shown superior catalytic efficiency and excellent stability under a wide range of pH (3.0-9.0), temperature (4-80 °C) and NaCl strength (0-300 mm). Interestingly, density functional theory (DFT) calculations reveal that the high catalytic performance is attributed to the activation of O2 by O2-Fe-N4 sites, which weakened the O─O bonds in the oxygen-to-water oxidation pathway. Furthermore, Fe-SAzyme is successfully applied for efficient aflatoxin B1 removal based on its robust laccase-like catalytic activity. This work provides a strategy for the rational design of laccase-like SAzymes, and the proposed catalytic mechanism will help to understand the coordination environment effect of SAzymes on laccase-like catalytic processes.

Avoiding common pitfalls in designing kinetic protocols for catalytic amyloid studies

Kinetic characterization of catalytic amyloids arguably presents a most challenging type of kinetic experiment where careful consideration of many factors is required. Here we outline common pitfalls in devising kinetic studies in such systems. Unlike the more specific protocols for various applications described in this volume, this chapter deals with general issues in setting up kinetic experiments that are incredibly important but often go without explicit mention in the specialized literature. The kinetic fundamentals described here can be also be of use to the enzymologists working with more traditional catalysts.

Biotechnological applications of amyloid fibrils

Protein aggregates and amyloid fibrils have special qualities and are used in a variety of biotechnological applications. They are extensively employed in bioremediation, biomaterials, and biocatalysis. Because of their capacity to encapsulate and release pharmaceuticals and their sensitivity to certain molecules, respectively, they are also used in drug delivery and biosensor applications. They have also demonstrated potential in the domains of food and bioremediation. Additionally, amyloid peptides have drawn interest in biological applications, especially in the investigation of illnesses like Parkinson's and Alzheimer's. The unique characteristics of amyloid fibrils, namely their mechanical strength and β-sheet structure, make them adaptable to a wide range of biotechnological uses. Even with their promise, one important factor to keep in mind before widely using modified amyloid materials is their potential toxicity. Thus, current research aims to overcome safety concerns while maximizing their potential.

Stopped-flow measurement of CO2 hydration activity by catalytic amyloids

With the ever-increasing rates of catalysis shown by catalytic amyloids, the use of faster characterization techniques is required for proper kinetic studies. The same is true for inherently fast chemical reactions. Carbon dioxide hydration is of significant interest to the field of enzyme design, given both carbonic anhydrases' status as a "perfect enzyme" and the central role carbonic anhydrase plays in the respiration and existence of all carbon-based life. Carbon dioxide is an underexplored hydrolysis substrate within the literature, and a lack of a direct spectroscopic marker for reaction monitoring can make studies more complex and require specialist equipment. Within this article we present a method for measuring the carbon dioxide hydration activity of amyloid fibrils.

Screening of oxidative behavior in catalytic amyloid assemblies

Once considered a thermodynamic minimum of the protein fold or as simply by-products of a misfolding process, amyloids are increasingly showing remarkable potential for promoting enzyme-like catalysis. Recent studies have demonstrated a diverse range of catalytic behaviors that amyloids can promote way beyond the hydrolytic behaviors originally reported. We and others have demonstrated the strong propensity of catalytic amyloids to facilitate redox reactions both in the presence and in the absence of metal cofactors. Here, we present a detailed protocol for measuring the oxidative ability of supramolecular peptide assemblies.

Simulating chemical reactions promoted by self-assembled peptides with catalytic properties

Peptides that self-assemble exhibit distinct three-dimensional structures and attributes, positioning them as promising candidates for biocatalysts. Exploring their catalytic processes enhances our comprehension of the catalytic actions inherent to self-assembling peptides, laying a theoretical foundation for creating novel biocatalysts. The investigation into the intricate reaction mechanisms of these entities is rendered challenging due to the vast variability in peptide sequences, their aggregated formations, supportive elements, structures of active sites, types of catalytic reactions, and the interplay between these variables. This complexity hampers the elucidation of the linkage between sequence, structure, and catalytic efficiency in self-assembling peptide catalysts. This chapter delves into the latest progress in understanding the mechanisms behind peptide self-assembly, serving as a catalyst in hydrolysis and oxidation reactions, and employing computational analyses. It discusses the establishment of models, selection of computational strategies, and analysis of computational procedures, emphasizing the application of modeling techniques in probing the catalytic mechanisms of peptide self-assemblies. It also looks ahead to the potential future trajectories within this research domain. Despite facing numerous obstacles, a thorough investigation into the structural and catalytic mechanisms of peptide self-assemblies, combined with the ongoing advancement in computational simulations and experimental methodologies, is set to offer valuable theoretical insights for the development of new biocatalysts, thereby significantly advancing the biocatalysis field.

A systematic review of coastal zone integrated waste management for sustainability strategies

Coastal areas stand out because of their rich biodiversity and high tourist potential due to their privileged geographical position. However, one of the main problems in these areas is the generation of waste and its management, which must consider technical and sustainable criteria. This work aims to conduct a systematic review of the scientific literature on integrated solid waste management (ISWM) by considering scientific publications on the scientific basis for the proposal of sustainability strategies in the context of use and efficiency. The overall method comprises i) Search strategy, merging and processing of the databases (Scopus and Web of Science); ii) Evolution of coastal zone waste management; iii) Systematic reviews on coastal landfills and ISWM in the context of the circular economy; and iv) Quantitative synthesis in integrated waste management. The results show 282 studies focused on coastal landfills and 59 papers on ISWM with the application of circular economy criteria. Systematic reviews allowed for the definition of criteria for the selection of favorable sites, such as i) sites far from the coastline, ii) impermeable soils at their base to avoid contamination of aquifers, iii) use of remote sensing and geographic information system tools for continuous monitoring, iv) mitigation of possible contamination of ecosystems, v) planning the possibility of restoration (reforestation) and protection of the environment. In coastal zones, it is necessary to apply the ISWM approach to avoid landfill flooding and protect the marine environment, reducing rubbish and waste on beaches and oceans. Therefore, applying the circular economy in ISWM is critical to sustainability in coastal environments, with the planet's natural processes and variations due to climate change.

Characterization of amyloid-like metal-amino acid assemblies with remarkable catalytic activity

While enzymes are potentially useful in various applications, their limited operational stability and production costs have led to an extensive search for stable catalytic agents that will retain the efficiency, specificity, and environmental-friendliness of natural enzymes. Despite extensive efforts, there is still an unmet need for improved enzyme mimics and novel concepts to discover and optimize such agents. Inspired by the catalytic activity of amyloids and the formation of amyloid-like assemblies by metabolites, our group pioneered the development of novel metabolite-metal co-assemblies (bio-nanozymes) that produce nanomaterials mimicking the catalytic function of common metalloenzymes that are being used for various technological applications. In addition to their notable activity, bio-nanozymes are remarkably safe as they are purely composed of amino acids and minerals that are harmless to the environment. The bio-nanozymes exhibit high efficiency and exceptional robustness, even under extreme conditions of temperature, pH, and salinity that are impractical for enzymes. Our group has recently also demonstrated the formation of ordered amino acid co-assemblies showing selective and preferential interactions comparable to the organization of residues in folded proteins. The identified bio-nanozymes can be used in various applications including environmental remediation, synthesis of new materials, and green energy.

Interactions between Lipid Vesicle Membranes and Single Amino Acid Fibrils: Probable Origin of Specific Neurological Disorders

Amyloid fibrils are known to be responsible for several neurological disorders, like Alzheimer's disease (AD), Parkinson's disease (PD), etc. For decades, mostly proteins and peptide-based amyloid fibrils have been focused on, and the topic has acknowledged the rise, development, understanding of, and controversy, as well. However, the single amino acid based amyloid fibrils, responsible for several disorders, such as phenylketonuria, tyrosenimia type II, hypermethioninemia, etc., have gotten scientific attention lately. To understand the molecular level pathogenesis of such disorders originated due to the accumulation of single amino acid-based amyloid fibrils, interaction of these fibrils with phospholipid vesicle membranes is found to be an excellent cell-free in vitro setup. Based on such an in vitro setup, these fibrils show a generic mechanism of membrane insertion driven by electrostatic and hydrophobic effects inside the membrane that reduces the integral rigidity of the membrane. Alteration of such fundamental properties of the membrane, therefore, might be referred to as one of the prime pathological factors for the development of these neurological disorders. Hence, such interactions must be investigated in cellular and intracellular compartments to design suitable therapeutic modulators against fibrils.

Bioinspired Amino Acid Based Materials in Bionanotechnology: From Minimalistic Building Blocks and Assembly Mechanism to Applications

Inspired by natural hierarchical self-assembly of proteins and peptides, amino acids, as the basic building units, have been shown to self-assemble to form highly ordered structures through supramolecular interactions. The fabrication of functional biomaterials comprised of extremely simple biomolecules has gained increasing interest due to the advantages of biocompatibility, easy functionalization, and structural modularity. In particular, amino acid based assemblies have shown attractive physical characteristics for various bionanotechnology applications. Herein, we propose a review paper to summarize the design strategies as well as research advances of amino acid based supramolecular assemblies as smart functional materials. We first briefly introduce bioinspired reductionist design strategies and assembly mechanism for amino acid based molecular assembly materials through noncovalent interactions in condensed states, including self-assembly, metal ion mediated coordination assembly, and coassembly. In the following part, we provide an overview of the properties and functions of amino acid based materials toward applications in nanotechnology and biomedicine. Finally, we give an overview of the remaining challenges and future perspectives on the fabrication of amino acid based supramolecular biomaterials with desired properties. We believe that this review will promote the prosperous development of innovative bioinspired functional materials formed by minimalistic building blocks.

Chiral Cux Coy S-Cuz S Nanoflowers with Bioinspired Enantioselective Catalytic Performances

Nanomaterials with biomimetic catalytic abilities have attracted significant attention. However, the stereoselectivity of natural enzymes determined by their unique configurations is difficult to imitate. In this work, a kind of chiral Cux Coy S-Cuz S nanoflowers (L/D-Pen-NFs) is developed, using porous Cux Coy S nanoparticles (NPs) as stamens, Cuz S sheets as petals, and chiral penicillamine as surface stabilizers. Compared to the natural laccase enzyme, L/D-Pen-NFs exhibit significant advantages in catalytic efficiency, stability against harsh environments, recyclability, and convenience in construction. Most importantly, they display high enantioselectivity toward chiral neurotransmitters, which is proved by L- and D-Pen-NFs' different catalytic efficiencies toward chiral enantiomers. L-Pen-NFs are more efficient in catalyzing the oxidation of L-epinephrine and L-dopamine compared with D-Pen-NFs. However, their catalytic efficiency in oxidizing L-norepinephrine and L-DOPA is lower than that of D-Pen-NFs. The reason for the difference in catalytic efficiency is the distinct binding affinities between Cux Coy S-Cuz S nano-enantiomers and chiral molecules. This work can spur the development of chiral nanostructures with biomimetic functions.

Histidine-Based Supramolecular Nanoassembly Exhibiting Dual Enzyme-Mimetic Functions: Altering the Tautomeric Preference of Histidine to Tailor Oxidative/Hydrolytic Catalysis

Challenges persist in replicating enzyme-like active sites with functional group arrangements in supramolecular catalysis. In this study, we present a supramolecular material comprising Fmoc-modified histidine and copper. We also investigated the impact of noncanonical amino acids (δmH and εmH), isomers of histidine, on the catalytic process. The Fmoc-δmH-based nanoassembly exhibits an approximately 15-fold increase in oxidative activity and an ∼50-fold increase in hydrolytic activity compared to Fmoc-εmH (kcat/Km). This distinction arises from differences in basicity and ligation properties between the ε- and δ-nitrogen of histidine. The addition of guanosine monophosphate further enhances the oxidative activity of the histidine- and methylated histidine-based catalysts. The Fmoc-δmH/Cu2+-based nanoassembly catalyzes the oxidation/hydrolysis cascade of 2',7'-dichlorofluorescein diacetate, benefiting from the synergistic effect between the copper center and the nonligating ε-nitrogen of histidine. These findings advance the biomimetic catalyst design and provide insights into the mechanistic role of essential residues in natural systems.

Phenylalanine-based fibrillar systems

Phenylketonuria (PKU) is an inborn metabolic disorder characterized by excess accumulation of phenylalanine (Phe) and its fibril formation, resulting in progressive intellectual disability. Several research groups have approached from various directions to understand the formation of toxic amyloid fibrils from the essential amino acid Phe. Different parameters like the nature of the solvent, pH, Phe concentration, temperature, etc. influence the fibril formation kinetics. In this article, we have summarized all major findings regarding the formation of Phe-based fibrils in aqueous and organic media and discussed how non-covalent interactions are involved in the self-assembly process using spectroscopic and microscopic techniques. The toxicity of Phe-based fibrils is compared with other neurodegenerative peptides. It is noted that the Phe-based fibrils can also induce various globular proteins into toxic fibrils. Later, we discuss the different approaches to inhibit fibril formation and reduce its toxicity. The presence of polyphenolic compounds, drugs, amino acids, nanoparticles, metal ions, crown ethers, and others showed a remarkable inhibitory effect on fibril formation. To the best of our knowledge, this is the first-ever etymological analysis of the Phe-fibrillar system and its inhibition to create a strong database against PKU.

Bacterial Nanocellulose/Copper as a Robust Laccase-Mimicking Bionanozyme for Catalytic Oxidation of Phenolic Pollutants

Industrial effluents containing phenolic compounds are a major public health concern and thus require effective and robust remediation technologies. Although laccase-like nanozymes are generally recognized as being catalytically efficient in oxidizing phenols, their support materials often lack resilience in harsh environments. Herein, bacterial nanocellulose (BNC) was introduced as a sustainable, strong, biocompatible, and environmentally friendly biopolymer for the synthesis of a laccase-like nanozyme (BNC/Cu). A native bacterial strain that produces nanocellulose was isolated from black tea broth fermented for 1 month. The isolate that produced BNC was identified as Bacillus sp. strain T15, and it can metabolize hexoses, sucrose, and less expensive substrates, such as molasses. Further, BNC/Cu nanozyme was synthesized using the in situ reduction of copper on the BNC. Characterization of the nanozyme by scanning electron microscopy (SEM) and X-ray diffraction (XRD) confirmed the presence of the copper nanoparticles dispersed in the layered sheets of BNC. The laccase-mimetic activity was assessed using the chromogenic redox reaction between 2,4-dichlorophenol (2,4-DP) and 4-aminoantipyrine (4-AP) with characteristic absorption at 510 nm. Remarkably, BNC/Cu has 50.69% higher catalytic activity than the pristine Cu NPs, indicating that BNC served as an effective biomatrix to disperse Cu NPs. Also, the bionanozyme showed the highest specificity toward 2,4-DP with a Km of 0.187 mM, which was lower than that of natural laccase. The bionanozyme retained catalytic activity across a wider temperature range with optimum activity at 85 °C, maintaining 38% laccase activity after 11 days and 46.77% activity after the fourth cycle. The BNC/Cu bionanozyme could efficiently oxidize more than 70% of 1,4-dichlorophenol and phenol in 5 h. Thereby, the BNC/Cu bionanozyme is described here as having an efficient ability to mimic laccase in the oxidation of phenolic compounds that are commonly released into the environment by industry.

Copper nanoparticles embedded fungal chitosan as a rational and sustainable bionanozyme with robust laccase activity for catalytic oxidation of phenolic pollutants

Despite their potential for oxidation of persistent environmental pollutants, the development of rational and sustainable laccase nanozymes with efficient catalytic performance remains a challenge. Herein, fungal-produced chitosan-copper (CsCu) is proposed as a rational and sustainable bionanozyme with intrinsic laccase activity. The CsCu nanozyme was prepared by in situ reduction of copper on chitosan extracted from Irpex sp. isolate AWK2 a native fungus, from traditional fermented foods, yielding a low molecular weight chitosan with a 70% degree of deacetylation. Characterizations of the nanozyme using SEM-EDX, XRD, and XPS confirmed the presence of a multi-oxidation state copper on the chitosan matrix which is consistent with the composition of natural laccase. The laccase memetic activity was investigated using 2,4-DP as a substrate which oxidized to form a reddish-pink color with 4-AP (λmax = 510 nm). The CsCu nanozyme showed 38% higher laccase activity than the pristine Cu NPs at pH 9, indicating enhanced activity in the presence of chitosan structure. Further, CsCu showed significant stability in harsh conditions and exhibited a lower Km (0.26 mM) which is competitive with that reported for natural laccase. Notably, the nanozyme converted 92% of different phenolic substrates in 5 h, signifying a robust performance for environmental remediation purposes.

Electron coupling effect-triggered monatomic copper laccase-mimicking nanozyme for the degradation and detection of guaiacol produced by Alicyclobacillus acidoterrestris

The generation of guaiacol by Alicyclobacillus acidoterrestris (A. acidoterrestris) in fruit juices negatively affects public health and causes severe environmental pollution. Therefore, the sensitive detection and efficient degradation of guaiacol in real samples are crucial. Here, we develop an electrochemical sensor utilizing a copper single-atom nanozyme (CuN4-G) to detect and degrade guaiacol at the picomolar level. Density functional theory (DFT) calculations verify that the bonding electron coupling effect in the CuN4-G facilitates rapid electron transfer, enhances electrical conductivity, and provides abundant active sites, thereby leading to exceptional catalytic performance. Moreover, CuN4-G demonstrates a Km value similar to that of natural laccase but a higher Vmax, highlighting its potential as a highly efficient biocatalyst. The CuN4-G-based electrochemical sensor achieves a detection from 5 to 50,000 pM for guaiacol, with a 1.2 pM (S/N = 3) detection limit. Additionally, CuN4-G-modified electrodes display high selectivity and excellent stability. CuN4-G nanozyme can keep its activity in conditions of pH (3-9), temperature (30-90 °C), ionic strength (0-400 mM), and organic solvent (0-50% (v/v)), overcoming the deficiencies of natural enzymes. Furthermore, our electrochemical sensor can not only accurately detect guaiacol, but also degrade it in actual fruit juice samples infected by A. acidoterrestris, demonstrating its potential applications in food and environmental monitoring.

Enzyme-Driven, Switchable Catalysis Based on Dynamic Self-Assembly of Peptides

Covalent regulatory systems of enzymes are widely used to modulate biological enzyme activities. Inspired by the regulation of reactive-site phosphorylation in organisms, we developed peptide-based catecholase mimetics with switchable catalytic activity and high selectivity through the co-assembly of nanofibers comprising peptides and copper ions (Cu2+ ). Through careful design and modification of the peptide backbone structure based on the change in the free energy of the system, we identified the peptide with the most effective reversible catalytic activity. Kinase/phosphatase switches were used to control the reversible transition of nanofiber formation and depolymerization, as well as to modulate the active-site microenvironment. Notably, the self-assembly and disassembly processes of nanofibers were simulated using coarse-grained molecular dynamics. Furthermore, theoretical calculations confirmed the coordination of the peptide and Cu2+ , forming a zipper-like four-ligand structure at the catalytically active center of the nanofibers. Additionally, we conducted a comprehensive analysis of the catalytic mechanism. This study opens novel avenues for designing biomimetic enzymes with ordered structures and dynamic catalytic activities.

Tailoring the Surface and Composition of Nanozymes for Enhanced Bacterial Binding and Antibacterial Activity

With the advantages of diverse structures, tunable enzymatic activity, and high stability, nanozymes are widely used in medicine, chemistry, food, environment, and other fields. As an alternative to traditional antibiotics, nanozymes attract more and more attention from the scientific researchers in recent years. Developing nanozymes-based antibacterial materials opens up a new avenue for the bacterial disinfection and sterilization. In this review, the classification of nanozymes and their antibacterial mechanisms are discussed. The surface and composition of nanozymes are critical for the antibacterial efficacy, which can be tailored to enhance both the bacterial binding and the antibacterial activity. On the one hand, the surface modification of nanozymes enables binding and targeting of bacteria that improves the antibacterial performance of nanozymes including the biochemical recognition, the surface charge, and the surface topography. On the other hand, the composition of nanozymes can be modulated to achieve enhanced antibacterial performance including the single nanozyme-mediated synergistic and multiple nanozymes-mediated cascade catalytic antibacterial applications. In addition, the current challenges and future prospects of tailoring nanozymes for antibacterial applications are discussed. This review can provide insights into the design of future nanozymes-based materials for the antibacterial treatments.

Stereoselective Plasmonic Interaction in Peptide-tethered Photopolymerizable Diacetylenes Doped with Chiral Gold Nanoparticles

Designing polymeric systems with ultra-high optical activity is instrumental in the pursuit of smart artificial chiroptical materials, including the fundamental understanding of structure/property relations. Herein, we report a diacetylene (DA) moiety flanked by chiral D- and L-FF dipeptide methyl esters that exhibits efficient topochemical photopolymerization in the solid phase to furnish polydiacetylene (PDA) with desired control over the chiroptical properties. The doping of the achiral gold nanoparticles provides plasmonic interaction with the PDAs to render asymmetric shape to the circular dichroism bands. With the judicious design of the chiral amino acid ligand appended to the AuNPs, we demonstrate the first example of selective chiral amplification mediated by stereo-structural matching of the polymer-plasmonic AuNP hybrid pairs. Such ordered self-assembly aided by topochemical polymerization in peptide-tethered PDA provides a smart strategy to produce soft responsive materials for applications in chiral photonics.

A supramolecular metalloenzyme possessing robust oxidase-mimetic catalytic function

Enzymes fold into unique three-dimensional structures to distribute their reactive amino acid residues, but environmental changes can disrupt their essential folding and lead to irreversible activity loss. The de novo synthesis of enzyme-like active sites is challenging due to the difficulty of replicating the spatial arrangement of functional groups. Here, we present a supramolecular mimetic enzyme formed by self-assembling nucleotides with fluorenylmethyloxycarbonyl (Fmoc)-modified amino acids and copper. This catalyst exhibits catalytic functions akin those of copper cluster-dependent oxidases, and catalytic performance surpasses to date-reported artificial complexes. Our experimental and theoretical results reveal the crucial role of periodic arrangement of amino acid components, enabled by fluorenyl stacking, in forming oxidase-mimetic copper clusters. Nucleotides provide coordination atoms that enhance copper activity by facilitating the formation of a copper-peroxide intermediate. The catalyst shows thermophilic behavior, remaining active up to 95 °C in an aqueous environment. These findings may aid the design of advanced biomimetic catalysts and offer insights into primordial redox enzymes.

Covalent Organic Framework Cladding on Peptide-Amphiphile-Based Biomimetic Catalysts

Peptide-based biomimetic catalysts are promising materials for efficient catalytic activity in various biochemical transformations. However, their lack of operational stability and fragile nature in non-aqueous media limit their practical applications. In this study, we have developed a cladding technique to stabilize biomimetic catalysts within porous covalent organic framework (COF) scaffolds. This methodology allows for the homogeneous distribution of peptide nanotubes inside the COF (TpAzo and TpDPP) backbone, creating strong noncovalent interactions that prevent leaching. We synthesized two different peptide-amphiphiles, C₁₀FFVK and C₁₀FFVR, with lysine (K) and arginine (R) at the C-termini, respectively, which formed nanotubular morphologies. The C₁₀FFVK peptide-amphiphile nanotubes exhibit enzyme-like behavior and efficiently catalyze C-C bond cleavage in a buffer medium (pH 7.5). We produced nanotubular structures of TpAzo-C₁₀FFVK and TpDPP-C₁₀FFVK through COF cladding by using interfacial crystallization (IC). The peptide nanotubes encased in the COF catalyze C-C bond cleavage in a buffer medium as well as in different organic solvents (such as acetonitrile, acetone, and dichloromethane). The TpAzo-C₁₀FFVK catalyst, being heterogeneous, is easily recoverable, enabling the reaction to be performed for multiple cycles. Additionally, the synthesis of TpAzo-C₁₀FFVK thin films facilitates catalysis in flow. As control, we synthesized another peptide-amphiphile, C₁₀FFVR, which also forms tubular assemblies. By depositing TpAzo COF crystallites on C₁₀FFVR nanotubes through IC, we produced TpAzo-C₁₀FFVR nanotubular structures that expectedly did not show catalysis, suggesting the critical role of the lysines in the TpAzo-C₁₀FFVK.

Optimization of heterologous production of Bacillus ligniniphilus L1 laccase in Escherichia coli through statistical design of experiments

Laccases are powerful multi-copper oxidoreductases that have wide applicability as "green" biocatalysts in biotechnological, bioremediation, and industrial applications. Sustainable production of large amounts of functional laccases from original sources is limited by low yields, difficulties in purification, slow growth of the organisms, and high cost of production. Harnessing the full potential of these versatile biocatalysts will require the development of efficient heterologous systems that allow high-yield, scalable, and cost-effective production. We previously cloned a temperature- and pH-stable laccase from Bacillus ligniniphilus L1 (L1-lacc) that demonstrated remarkable activity in the oxidation of lignin and delignification for bioethanol production. However, L1-lacc is limited by low enzyme yields in both the source organism and heterologous systems. Here, to improve production yields and lower the cost of production, we optimized the recombinant E. coli BL21 strain for high-level production of L1-lacc. Several culture medium components and fermentation parameters were optimized using one-factor-at-a-time (OFAT) and Plackett-Burman design (PBD) to screen for important factors that were then optimized using response surface methodology (RSM) and an orthogonal design. The optimized medium composition had compound nitrogen (15.6 g/L), glucose (21.5 g/L), K₂HPO₄ (0.15 g/L), MgSO₄ (1 g/L), and NaCl (7.5 g/L), which allowed a 3.3-fold yield improvement while subsequent optimization of eight fermentation parameters achieved further improvements to a final volumetric activity titer of 5.94 U/mL in 24 h. This represents a 7-fold yield increase compared to the initial medium and fermentation conditions. This work presents statistically guided optimization strategies for improving heterologous production of a bacterial laccase that resulted in a high-yielding, cost-efficient production system for an enzyme with promising applications in lignin valorization, biomass processing, and generation of novel composite thermoplastics.

Self-assembling nanoarchitectonics of size-controllable celastrol nanoparticles for efficient cancer chemotherapy with reduced systemic toxicity

Celastrol, extracted from Tripterygium wilfordii Hook F, is one of the most promising natural extract for cancer treatment. Nevertheless, insufficient tumor retention and severe systemic toxicity still hinder its application. Herein, we report for the first time that Celastrol can directly self-assemble into size-controllable nanoparticles through the anti-solvent method by using different good solvent or by the variation of Celastrol concentrations. In vitro anti-cancer experiment revealed that the as-prepared nanoparticles can kill MCF-7 cells more effectively. Moreover, the nanoparticles can efficiently accumulate in tumors of the tumor bearing mice after tail vein injection. Under the administration of lethal dosage of Celastrol, the tumors are greatly suppressed and the mice maintain the activity. These results demonstrate that anti-solvent method may be a promising strategy to fabricate Celastrol nano-drugs with controllable size and less systemic toxicity for further clinical cancer treatment.

Direct and Specific Detection of Glyphosate Using a Phosphatase-like Nanozyme-Mediated Chemiluminescence Strategy

Most organophosphorus pesticide (OP) sensors reported in the literature rely on the inhibition effect of OPs on the activity of acetylcholinesterase (AChE), which suffer from the drawbacks of lack of selective recognition of OPs, high cost, and poor stability. Herein, we proposed a novel chemiluminescence (CL) strategy for the direct detection of glyphosate (an organophosphorus herbicide) with high sensitivity and specificity, which is based on the porous hydroxy zirconium oxide nanozyme (ZrO_X-OH) obtained via a facile alkali solution treatment of UIO-66. ZrO_X-OH displayed excellent phosphatase-like activity, which could catalyze the dephosphorylation of 3-(2'-spiroadamantyl)-4-methoxy-4-(3'-phosphoryloxyphenyl)-1,2-dioxetane (AMPPD) to generate strong CL. The experimental results showed that the phosphatase-like activity of ZrO_X-OH is closely related to the content of hydroxyl groups on their surface. Interestingly, ZrO_X-OH with phosphatase-like properties exhibited a unique response to glyphosate because of the consumption of the surface hydroxyl group by the unique carboxyl group of glyphosates and was thus employed to develop a CL sensor for direct and selective detection of glyphosate without using bio-enzymes. The recovery for glyphosate detection of cabbage juice ranged from 96.8 to 103.0%. We believe that the as-proposed CL sensor based on ZrO_X-OH with phosphatase-like properties supplies a simpler and more highly selective approach for OP assay and provides a new method for the development of CL sensors for the direct analysis of OPs in real samples.

Entropically-Driven Co-assembly of l-Histidine and l-Phenylalanine to Form Supramolecular Materials

Molecular self- and co-assembly allow the formation of diverse and well-defined supramolecular structures with notable physical properties. Among the associating molecules, amino acids are especially attractive due to their inherent biocompatibility and simplicity. The biologically active enantiomer of l-histidine (l-His) plays structural and functional roles in proteins but does not self-assemble to form discrete nanostructures. In order to expand the structural space to include l-His-containing materials, we explored the co-assembly of l-His with all aromatic amino acids, including phenylalanine (Phe), tyrosine (Tyr), and tryptophan (Trp), all in both enantiomeric forms. In contrast to pristine l-His, the combination of this building block with all aromatic amino acids resulted in distinct morphologies including fibers, rods, and flake-like structures. Electrospray ionization mass spectrometry (ESI-MS) indicated the formation of supramolecular co-assemblies in all six combinations, but time-of-flight secondary-ion mass spectrometry (ToF-SIMS) indicated the best seamless co-assembly occurs between l-His and l-Phe while in the other cases, different degrees of phase separation could be observed. Indeed, isothermal titration calorimetry (ITC) suggested the highest affinity between l-His and l-Phe where the formation of co-assembled structures was driven by entropy. In accordance, among all the combinations, the co-assembly of l-His and l-Phe produced single crystals. The structure revealed the formation of a 3D network with nanocavities stabilized by hydrogen bonding between -N (l-His) and -NH (l-Phe). Taken together, using the co-assembly approach we expanded the field of amino acid nanomaterials and showed the ability to obtain discrete supramolecular nanostructures containing l-His based on its specific interactions with l-Phe.

Bioinspired Coassembly of Copper Ions and Nicotinamide Adenine Dinucleotides for Single-Site Nanozyme with Dual Catalytic Functions

Nanozymes can imitate the catalytic properties of natural enzymes while overcoming the limitations of natural enzymes such as high cost, poor robustness, and difficulty in recycling. However, rational design and facile preparation of nanozymes are still in demand. Inspired by the chemical structure of laccase, we report an amorphous metal-organic coordination nanocomposite named CuNAD, which is composed of copper ions and nicotinamide adenine dinucleotide (NAD⁺) via a simple coordinating coassembly process. As a single-site nanozyme, CuNAD exhibits excellent robustness under extreme conditions, significantly stronger catalytic activity for phenolic compounds, and 4.02-fold higher sensitivity for epinephrine detection than laccase. Furthermore, by breaking through the functional constraints of laccase, CuNAD is also able to activate H₂O₂ at neutral pH, benefiting a one-step chromogenic detection platform for cholesterol. This facile approach demonstrates the potential to develop single-site nanozymes by biomimicking natural enzymes and may boost more insights into the structure-function relationship of nanozymes.

Citric acid modified ultrasmall copper peroxide nanozyme for in situ remediation of environmental sulfonylurea herbicide contamination

Herbicide residues in the environment threaten high-quality agriculture and human health. Consequently, in situ remediation of herbicide contamination is vital. We synthesized a novel self-catalyzed nanozyme, ultrasmall (2-3 nm) copper peroxide nanodots modified by citric acid (CP@CA) for this purpose, which can break down into H₂O₂ and Cu²⁺ in water or soil. Ubiquitous glutathione reduces Cu²⁺ into Cu⁺, which promotes the decomposition of H₂O₂ into •OH through a Fenton-like reaction under mild acid conditions created by the presence of citric acid. The generated •OH efficiently degrade nicosulfuron in water and soil, and the maximum degradation efficiency could be achieved at 97.58% in water at 56 min. The possible degradation mechanisms of nicosulfuron were proposed through the 25 intermediates detected. The overall ecotoxicity of the nicosulfuron system was significantly reduced after CP@CA treatment. Furthermore, CP@CA had little impact on active components of soil bacterial community. Moreover, CP@CA nanozyme could effectively remove seven other sulfonylurea herbicides from the water. In this paper, a high-efficiency method for herbicide degradation was proposed, which provides a new reference for the in situ remediation of herbicide pollution.

Supramolecular assembly of benzophenone alanine and copper presents high laccase-like activity for the degradation of phenolic pollutants

Laccases are multicopper oxidases of significant importance for the degradation of phenolic pollutants. Because of the inherent defects of natural laccases in practical applications, herein, we discovered highly effective and non-cytotoxic laccase-like metallo-nanofibers based on the supramolecular assembly of single unnatural amino acid, benzophenone-alanine (BpA), in combination with copper ions. Structural analysis revealed that the catalytic BpA-Cu nanofibers possess a Cu(I)-Cu(II) electron transfer system similar to that in natural laccase. Our BpA-Cu nanofibers exhibit 4 times higher substrate affinity and 24% higher catalytic efficiency than the well-known high-performance industrialized laccase (Novozym 51003) in 2,4-dichlorophenol degradation. In addition, the BpA-Cu nanofibers were demonstrated to be stable (>75% residual activity) in long-term storage at a wide range of pH, ionic strength, temperature, ethanol, and water sample, and to be readily recovered for pollutant degradation, keeping 83% of the laccase activity after 10 catalytic recycles. Remarkably, the nanofibers displayed a wide substrate spectrum, detecting and degrading a variety of phenolic pollutants with high activity than other laccase mimics reported in the literature. Furthermore, the biocompatibility of the material was proved with cultured cells. These findings demonstrated the potential of BpA-Cu nanofibers in mimicking laccases for environmental remediation.

Self-Assembling Peptide-Based Functional Biomaterials

Peptides can self-assemble into various hierarchical nanostructures through noncovalent interactions and form functional materials exhibiting excellent chemical and physical properties, which have broad applications in bio-/nanotechnology. The self-assembly mechanism, self-assembly morphology of peptide supramolecular architecture and their various applications, have been widely explored which have the merit of biocompatibility, easy preparation, and controllable functionality. Herein, we introduce the latest research progress of self-assembling peptide-based nanomaterials and review their applications in biomedicine and optoelectronics, including tissue engineering, anticancer therapy, biomimetic catalysis, energy harvesting. We believe that this review will inspire the rational design and development of novel peptide-based functional bio-inspired materials in the future.

Solid Migration to Assemble a Flower-like Nanozyme with Highly Dense Single Copper Sites for Specific Phenol Oxidation

Nanozymes with high catalytic stability and sustainability have emerged as powerful competitors to natural enzymes for diverse biocatalytic applications. However, constructing a nanozyme with high specificity is one of their biggest challenges. Herein, we develop a facile solid migration strategy to access a flower-like single copper site nanozyme (Cu SSN) via direct transformation of copper foam activated by 2-methylimidazole. With highly clustered CuN₃ sites whose local structure is similar to that of natural polyphenol oxidase, the Cu SSN exhibits excellent activity and specificity to oxidize phenols without peroxidase-like activity. Furthermore, the Cu SSN shows high sensitivity in the colorimetric detection of epinephrine with a low detection limit of 0.10 μg mL^-1, exceeding that of most previously reported enzyme-mimicking catalysts. This work not only provides a simple method for the large-scale preparation of high-performance nanozymes but also offers an inspiration for the design of highly specific nanozymes by mimicking the synergy among sites in natural enzymes.

Axial N Ligand-Modulated Ultrahigh Activity and Selectivity Hyperoxide Activation over Single-Atoms Nanozymes

Learning and studying the structure-activity relationship in the bio-enzymes is conducive to the design of nanozymes for energy and environmental application. Herein, Fe single-atom nanozymes (Fe-SANs) with Fe-N5 site, inspired by the structure of cytochromes P450 (CYPs), are developed and characterized. Similar to the CYPs, the hyperoxide can activate the Fe(III) center of Fe-SANs to generate Fe(IV)O intermediately, which can transfer oxygen to the substrate with ultrafast speed. Particularly, using the peroxymonosulfate (PMS)-activated Fe-SANs to oxidize sulfamethoxazole, a typical antibiotic contaminant, as the model hyperoxides activation reaction, the excellent activity within 284 min-1 g-1 (catalyst) mmol-1 (PMS) oxidation rate and 91.6% selectivity to the Fe(IV)O intermediate oxidation are demonstrated. More importantly, instead of promoting PMS adsorption, the axial N ligand modulates the electron structure of FeN5 SANs for the lower reaction energy barrier and promotes electron transfer to PMS to produce Fe(IV)O intermediate with high selectivity. The highlight of the axial N coordination in the nanozymes in this work provides deep insight to guide the design and development of nanozymes nearly to the bio-enzyme with excellent activity and selectivity.

Supramolecular enzyme-mimicking catalysts self-assembled from peptides

Natural enzymes catalyze biochemical transformations in superior catalytic efficiency and remarkable substrate specificity. The excellent catalytic repertoire of enzymes is attributed to the sophisticated chemical structures of their active sites, as a result of billions-of-years natural evolution. However, large-scale practical applications of natural enzymes are restricted due to their poor stability, difficulty in modification, and high costs of production. One viable solution is to fabricate supramolecular catalysts with enzyme-mimetic active sites. In this review, we introduce the principles and strategies of designing peptide-based artificial enzymes which display catalytic activities similar to those of natural enzymes, such as aldolases, laccases, peroxidases, and hydrolases (mainly the esterases and phosphatases). We also discuss some multifunctional enzyme-mimicking systems which are capable of catalyzing orthogonal or cascade reactions. We highlight the relationship between structures of enzyme-like active sites and the catalytic properties, as well as the significance of these studies from an evolutionary point of view.

Small Peptides in the Detection of Mycotoxins and Their Potential Applications in Mycotoxin Removal

Mycotoxins pose significant risks to humans and livestock. In addition, contaminated food- and feedstuffs can only be discarded, leading to increased economic losses and potential ecological pollution. Mycotoxin removal and real-time toxin level monitoring are effective approaches to solve this problem. As a hot research hotspot, small peptides derived from phage display peptide libraries, combinatorial peptide libraries, and rational design approaches can act as coating antigens, competitive antigens, and anti-immune complexes in immunoassays for the detection of mycotoxins. Furthermore, as a potential approach to mycotoxin degradation, small peptides can mimic the natural enzyme catalytic site to construct artificial enzymes containing oxidoreductases, hydrolase, and lyase activities. In summary, with the advantages of mature synthesis protocols, diverse structures, and excellent biocompatibility, also sharing their chemical structure with natural proteins, small peptides are widely used for mycotoxin detection and artificial enzyme construction, which have promising applications in mycotoxin degradation. This paper mainly reviews the advances of small peptides in the detection of mycotoxins, the construction of peptide-based artificial enzymes, and their potential applications in mycotoxin control.

Catalytically Active Amyloids as Future Bionanomaterials

Peptides and proteins can aggregate into highly ordered and structured conformations called amyloids. These supramolecular structures generally have convergent features, such as the formation of intermolecular beta sheets, that lead to fibrillary architectures. The resulting fibrils have unique mechanical properties that can be exploited to develop novel nanomaterials. In recent years, sequences of small peptides have been rationally designed to self-assemble into amyloids that catalyze several chemical reactions. These amyloids exhibit reactive surfaces that can mimic the active sites of enzymes. In this review, I provide a state-of-the-art summary of the development of catalytically active amyloids. I will focus especially on catalytic activities mediated by hydrolysis, which are the most studied examples to date, as well as novel types of recently reported activities that promise to expand the possible repertoires. The combination of mechanical properties with catalytic activity in an amyloid scaffold has great potential for the development of future bionanomaterials aimed at specific applications.

Lighting Up Agricultural Sustainability in the New Era through Nanozymology: An Overview of Classifications and Their Agricultural Applications

With the concept of sustainable agriculture receiving increasing attention from humankind, nanozymes, nanomaterials with enzyme-like activity but higher environmental endurance and longer-term stability than natural enzymes, have enabled agricultural technologies to be reformative, economic, and portable. Benefiting from their multiple catalytic activities and renewable nanocharacteristics, nanozymes can shine in agricultural scenarios using enzyme engineering and nanoscience, acting as sustainable toolboxes to improve agricultural production and reduce the risk to agricultural systems. Herein, we comprehensively discuss the classifications of nanozymes applied in current agriculture, including peroxidase-like, oxidase-like, catalase-like, superoxide dismutase-like, and laccase-like nanozymes, as well as their biocatalytic mechanisms. Especially, different applications of nanozymes in agriculture are deeply reviewed, covering crop protection and nutrition, agroenvironmental remediation and monitoring, and agroproduct quality monitoring. Finally, the challenges faced by nanozymes in agricultural applications are proposed, and we expect that our review can further enhance agricultural sustainability through nanozymology.

Switchable Enzyme-mimicking catalysts Self-Assembled from de novo designed peptides and DNA G-quadruplex/hemin complex

Reconstruction of enzymatic active site in an artificial system is key to achieving high catalytic efficiency. Herein, we report the self-assembly of the lysine-containing peptides with guanine-rich DNA and hemin to form peroxidase-mimicking active sites and catalytic nanoparticles. The DNA strand self-folds into a G-quadruplex structure that provides a supramolecular scaffold and a potential axial ligand for hemin. The β-sheet forming capability of the lysine-containing peptides is found to affect the catalytic synergy between the G-quadruplex DNA and the peptide. It is hypothesized that the β-sheet formation of the peptides results in the enrichment of the lysine residues, which distribute on the distal side of hemin to promote the formation of Compound I, like distal arginine residue in natural heme pocket. Incorporation of the histidine residues into the lysine-containing peptides further enhanced the hemin activities, indicating the cooperation between the lysine and histidine. Furthermore, the peptide/DNA/hemin complexes can be switched between active and inactive state by reversible formation and deformation of the DNA G-quadruplex, which was attributed to the peptides-promoted conformational changes of the DNA components. This work opens an avenue to mimic the catalytic residues and their spatial distribution in the natural enzymes, and shed light on the design of the smart biocatalysts that can respond to the environmental stimuli.

What are the inorganic nanozymes? Artificial or inorganic enzymes!

The research on inorganic nanozymes remains very active since the first paper on the “intrinsic peroxidase-like properties of ferromagnetic nanoparticles” was published in Nature Nanotechnology in 2007. However, there is...