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Nanomaterials excel in mimicking the structure and function of natural enzymes while being far more interesting in terms of structural stability, functional versatility, recyclability, and large‐scale preparation. Herein, the story assembles hemin, histidine analogs, and G‐quadruplex DNA in a catalytically competent supramolecular assembly referred to as assembly‐activated hemin enzyme (AA‐heminzyme). The catalytic properties of AA‐heminzyme are investigated both in silico (by molecular docking and quantum chemical calculations) and in vitro (notably through a systematic comparison with its natural counterpart horseradish peroxidase, HRP). It is found that this artificial system is not only as efficient as HRP to oxidize various substrates (with a turnover number kcat of 115 s−1) but also more practically convenient (displaying better thermal stability, recoverability, and editability) and more economically viable, with a catalytic cost amounting to <10% of that of HRP. The strategic interest of AA‐heminzyme is further demonstrated for both industrial wastewater remediation and biomarker detection (notably glutathione, for which the cost is decreased by 98% as compared to commercial kits). [ABSTRACT FROM AUTHOR]

The introduction of an abiological catalytic group into the binding pocket of a protein host allows for the expansion of enzyme chemistries. Here, we report the generation of an artificial enzyme by genetic encoding of a non‐canonical amino acid that contains a secondary amine side chain. The non‐canonical amino acid and the binding pocket function synergistically to catalyze the asymmetric nitrocyclopropanation of α,β‐unsaturated aldehydes by the iminium activation mechanism. The designer enzyme was evolved to an optimal variant that catalyzes the reaction at high conversions with high diastereo‐ and enantioselectivity. This work demonstrates the application of genetic code expansion in enzyme design and expands the scope of enzyme‐catalyzed abiological reactions. [ABSTRACT FROM AUTHOR]

Enzymes have gained their unique efficiency and catalytic activity through billions of years of evolution, perfecting their active site to a desired reaction. Inspired by nature, a novel enzyme‐mimicking platform is designed based on stable protein 1 (SP1) to create a nano‐compartment that mimics peroxidase activity. The biohybrid reveals enhanced activity over the hemin cofactor alone and improved stability in organic solvents in comparison to native peroxidase. Furthermore, the utilization of the obtained biohybrid in an optical glucose biosensing platform is shown. The biohybrid crystallographic structure is solved, indicating that the SP1 structure is not affected by the hemin coordination. This work opens the path for developing new cofactor binding centers in engineered protein scaffolds for various artificial catalytic processes. [ABSTRACT FROM AUTHOR]

Secondary amines, due to their reactivity, can transform protein templates into catalytically active entities, accelerating the development of artificial enzymes. However, existing methods, predominantly reliant on modified ligands or N‐terminal prolines, impose significant limitations on template selection. In this study, genetic code expansion was used to break this boundary, enabling secondary amines to be incorporated into alternative proteins and positions of choice. Pyrrolysine analogues carrying different secondary amines could be incorporated into superfolder green fluorescent protein (sfGFP), multidrug‐binding LmrR and nucleotide‐binding dihydrofolate reductase (DHFR). Notably, the analogue containing a D‐proline moiety demonstrated both proteolytic stability and catalytic activity, conferring LmrR and DHFR with the desired transfer hydrogenation activity. While the LmrR variants were confined to the biomimetic 1‐benzyl‐1,4‐dihydronicotinamide (BNAH) as the hydride source, the optimal DHFR variant favorably used the pro‐R hydride from NADPH for stereoselective reactions (e.r. up to 92 : 8), highlighting that a switch of protein template could broaden the nucleophile option for catalysis. Owing to the cofactor compatibility, the DHFR‐based secondary amine catalysis could be integrated into an enzymatic recycling scheme. This established method shows substantial potential in enzyme design, applicable from studies on enzyme evolution to the development of new biocatalysts. [ABSTRACT FROM AUTHOR]

Abstract Nanomaterials excel in mimicking the structure and function of natural enzymes while being far more interesting in terms of structural stability, functional versatility, recyclability, and large‐scale preparation. Herein, the story assembles hemin, histidine analogs, and G‐quadruplex DNA in a catalytically competent supramolecular assembly referred to as assembly‐activated hemin enzyme (AA‐heminzyme). The catalytic properties of AA‐heminzyme are investigated both in silico (by molecular docking and quantum chemical calculations) and in vitro (notably through a systematic comparison with its natural counterpart horseradish peroxidase, HRP). It is found that this artificial system is not only as efficient as HRP to oxidize various substrates (with a turnover number kcat of 115 s−1) but also more practically convenient (displaying better thermal stability, recoverability, and editability) and more economically viable, with a catalytic cost amounting to

The folding of proteins into intricate three‐dimensional structures to achieve biological functions, such as catalysis, is governed by both kinetic and thermodynamic controls. The quest to design artificial enzymes using minimalist peptides seeks to emulate supramolecular structures existing in a catalytically active state. Drawing inspiration from the nuanced process of protein folding, our study explores the enzyme‐like activity of amphiphilic peptide nanosystems in both equilibrium and non‐equilibrium states, featuring the formation of supramolecular nanofibrils and nanosheets. In contrast to thermodynamically stable nanosheets, the kinetically trapped nanofibrils exhibit dynamic characteristics (e.g. rapid molecular exchange and relatively weak intermolecular packing), resulting in a higher hydrolase‐mimicking activity. We emphasize that a supramolecular microenvironment characterized by an optimal local polarity, microviscosity, and β‐sheet hydrogen bonding is conducive to both substrate binding and ester bond hydrolysis. Our work underscores the pivotal role of both thermodynamic and kinetic control in impacting biomimetic catalysis and sheds a light on the development of artificial enzymes. [ABSTRACT FROM AUTHOR]

Enzymes have gained their unique efficiency and catalytic activity through billions of years of evolution, perfecting their active site to a desired reaction. Inspired by nature, a novel enzyme‐mimicking platform is designed based on stable protein 1 (SP1) to create a nano‐compartment that mimics peroxidase activity. The biohybrid reveals enhanced activity over the hemin cofactor alone and improved stability in organic solvents in comparison to native peroxidase. Furthermore, the utilization of the obtained biohybrid in an optical glucose biosensing platform is shown. The biohybrid crystallographic structure is solved, indicating that the SP1 structure is not affected by the hemin coordination. This work opens the path for developing new cofactor binding centers in engineered protein scaffolds for various artificial catalytic processes.

DNase‐catalyzed hydrolysis of extracellular DNA (eDNA) has been widely employed to eradicate intractable biofilms. Although aggregation‐induced emission (AIE) has become the ideal tool for killing planktonic bacteria, AIE luminogens (AIEgens) often lack DNase‐mimetic activity, so as to suffer from poor anti‐biofilm capacity. Here, an "AIEzyme", a kind of AIE nanomaterial with enzyme‐like activity, is designed and synthesized, where the AIEgens are used as the ligands of Zr‐based coordination polymer nanoparticles. Not only does AIEzyme have enduring DNase‐mimetic activity with low activation energy, but also structural rigidity‐stabilized fluorescence. Due to the long‐acting hydrolysis for eDNA in biofilm, AIEzyme can efficiently disorganize the established biofilms with good penetrability and realize the healing of superbug‐infected wounds under only one dose of AIEzyme. This work provides a strategy to endow ordinary AIEgens with DNase‐like and anti‐biofilm activities. Moreover, AIEzymes can be observed by virtue of their own AIE character, facilitating the study on self‐positioning and residual amount of AIEzymes in wounds. The concept "AIEzyme" would hopefully stimulate the tremendous expansion for the tool kits and the application of AIEgens and artificial enzymes. [ABSTRACT FROM AUTHOR]

Abstract DNase‐catalyzed hydrolysis of extracellular DNA (eDNA) has been widely employed to eradicate intractable biofilms. Although aggregation‐induced emission (AIE) has become the ideal tool for killing planktonic bacteria, AIE luminogens (AIEgens) often lack DNase‐mimetic activity, so as to suffer from poor anti‐biofilm capacity. Here, an “AIEzyme”, a kind of AIE nanomaterial with enzyme‐like activity, is designed and synthesized, where the AIEgens are used as the ligands of Zr‐based coordination polymer nanoparticles. Not only does AIEzyme have enduring DNase‐mimetic activity with low activation energy, but also structural rigidity‐stabilized fluorescence. Due to the long‐acting hydrolysis for eDNA in biofilm, AIEzyme can efficiently disorganize the established biofilms with good penetrability and realize the healing of superbug‐infected wounds under only one dose of AIEzyme. This work provides a strategy to endow ordinary AIEgens with DNase‐like and anti‐biofilm activities. Moreover, AIEzymes can be observed by virtue of their own AIE character, facilitating the study on self‐positioning and residual amount of AIEzymes in wounds. The concept “AIEzyme” would hopefully stimulate the tremendous expansion for the tool kits and the application of AIEgens and artificial enzymes.

Natural enzymes are used as special reagents for the preparation of electrochemical (bio)sensors due to their ability to catalyze processes, improving the selectivity of detection. However, some drawbacks, such as denaturation in harsh experimental conditions and their rapid de- gradation, as well as the high cost and difficulties in recycling them, restrict their practical applications. Nowadays, the use of artificial enzymes, mostly based on nanomaterials, mimicking the functions of natural products, has been growing. These so-called nanozymes present several advantages over natural enzymes, such as enhanced stability, low cost, easy production, and rapid activity. These outstanding features are responsible for their widespread use in areas such as catalysis, energy, imaging, sensing, or biomedicine. These materials can be divided into two main groups: metal and carbon-based nanozymes. The latter provides additional advantages compared to metal nanozymes, i.e., stable and tuneable activity and good biocompatibility, mimicking enzyme activities such as those of peroxidase, catalase, oxidase, superoxide dismutase, nuclease, or phosphatase. In this review article, we have focused on the use of carbon-based nanozymes for the preparation of electrochemical (bio)sensors. The main features of the most recent applications have been revised and illustrated with examples selected from the literature over the last four years (since 2020). [ABSTRACT FROM AUTHOR]

In recent years, Prussian blue nanoparticles (PB-NPs) and theire analogues, that exhibit an increased catalytic activity, have attracted considerable attention in nanotechnology. Such nanoparticles are regarded as an alternative to natural enzymes and are intensively used in biosensorics, diagnostics and experimental biomedicine. Recently, it has been shown that Prussian blue nanoparticles and their analogs, also referred to as “nanozymes”, can be used as active oxygen scavengers and antibacterial or anti-inflammatory drugs due to their polyenzymatic activities, namely oxidase, peroxidase, superoxide dismutase. Their excellent biocompatibility and biodegradability mean that they are ideal for in vivo use. Prussian blue nanoparticles are highly efficient electron transporters that engage in oxidation and reduction activity, which makes them promising mediators and catalysts of reactions. They also show great promise as nanodrug carriers and biological detection sensors due to their large specific surface area, unique chemical characteristics, and variable qualities, which, more importantly, can significantly increase their therapeutic effect. Prussian blue nanoparticles, as therapeutic and diagnostic tools, have achieved significant success in biological nanomedicine. This review is devoted to the methods of synthesis of Prussian blue nanoparticles, the study of their structure, properties and role in the creation of analytical sensors and their promising significance for biomedicine.

In the present study, a new voltammetric method is introduced for the determination of kinetic parameters of artificial metalloenzymes (biomimetic complexes) mimicking the catecholase activity towards 3,5‐di‐tert‐butylcatechol (3,5‐DTBC) or 2,5‐di‐tert‐butylhydroquinone, and representing a promising alternative to common spectrophotometric method. To demonstrate the effectiveness of the electrochemical approach, two binuclear copper(II) complexes bearing the same pentadentate ligand and different ionic ligands were selected. Apparent kinetic parameters, such as maximum velocity (Vmax), Michaelis‐Menten constant (Km), and turnover number (kcat), obtained by the described method employing differential‐pulse voltammetry were in good agreement with the data evaluated from UV‐Vis spectrophotometric measurements. [ABSTRACT FROM AUTHOR]

[Display omitted] As bridging species between short peptides and macromolecular proteins, peptide assemblies not only provide a supramolecular approach for the fabrication of controllable molecular machines with enzyme-like functions, but also a simplified model for understanding the catalytic mechanism of natural enzymes. In this study, we focused on probing the effect of microenvironment on the catalytic behavior of peptide assemblies. Upon simply replacing the X residue in Fmoc-FFXAH-CONH 2 , we realized the modulation of the microenvironment of the amyloid assemblies, which thus appeared esterase-like function with different catalytic abilities. The chemistry, structure and activity were analyzed to explore the principles that how the hydrophobic, charged, polar and chiral microenvironment deciding the catalytic behavior of the esterase mimic. In addition, we also presented the potential of the catalytic assemblies in the encapsulation, delivery and enzymatic metabolization of a mutual prodrug. This work sheds new insights for understanding the structure–function relationship of catalytic peptide assemblies and natural enzymes, and also provides a new avenue for the designing of artificial enzymes with better functions. [ABSTRACT FROM AUTHOR]

Signal transduction across lipid bilayers is of profound importance in biological processes. In biological systems, natural enzymes mediate biochemical effects by binding to substrates and facilitating the conversion of external signals into physiological responses. Sequential transmission of biological signals from one enzyme to the next promotes signal transduction with feedforward and feedback mechanisms. Reconstructing these processes in an artificial system provides potential applications and offers a new way to understand fundamental biological processes in depth. However, the design of artificial signal transduction systems regulated by artificial enzyme receptors in a predictable and intelligent manner remains a challenge. Herein, benefiting from the polarity-regulated characteristics of Se-containing compounds with artificial glutathione peroxidase (GPx) activity, we constructed an artificial transmembrane signaling receptor with a Se-containing GPx-like recognition head group, a membrane-anchoring group, and a pre-enzyme end group. The artificial supramolecular signal transduction system containing such signal transduction receptors extends the range of signaling systems based on enzyme regulation, which provides a new way to study natural signal processes in cells and artificially regulated biological processes. [ABSTRACT FROM AUTHOR]

An immunosensor based on gold nanorods (AuNRs) etchant activity of a metal–organic framework (MOF): MIL-88B(Fe)-reduced graphene oxide (rGMOF) was developed for the determination of prostate-specific antigen (PSA). Several techniques, including FTIR, UV–Vis spectrophotometry, XRD, and electron microscopy, were employed to characterize the MOFs containing iron-oxygen clusters on the surface of reduced graphene oxide. Enzyme mimetic activity of rGMOF before and after bioconjugation with antibodies was calculated as 8.4 and 2.5 U mg−1, respectively. The primary anti-PSA was conjugated to a magnetic bead and used as PSA-specific capturing. Then, the secondary anti-PSA was grafted to the rGMOF. In the presence of antigen, an immuno-sandwich was formed between the conjugations mentioned above. Afterward, AuNRs were etched by rGMOF, and the related spectrum was recorded in the wavelength range 350 to 900 nm. By progressing the etching procedure, the longitudinal LSPR peak of AuNRs was gradually blue-shifted with a linear correlation with the PSA concentration from 0.1 pg mL−1 to 100 ng mL−1. The detection limit was 0.09 pg mL−1. The proposed immunosensor was successfully employed to determine PSA levels in real samples. Since the obtained results showed an excellent correlation with those acquired by the chemiluminescence gold standard method, it has the potential for PSA determination in clinical assays. [ABSTRACT FROM AUTHOR]

Integrating artificial enzymes onto nanostructures target‐ and site‐specifically is still a challenge. Here we show that target miRNAs trigger the formation of DNAzyme site‐specifically at the tip of filamentous phage for detecting miRNA biomarkers. Through an antibody‐modified oligonucleotide, the tip of the phage with magnetic nanoparticles on the sidewall captures a target miRNA, inducing the formation of DNAzyme that extends from the phage tip through a hybridization chain reaction. After magnetic separation, the resultant complex catalyzes a colorimetric reaction with the signal correlated to target concentrations, leading to the quantification of miRNAs with a detection limit of 5.0 fM, about 103 folds lower than the phage‐free approach. Our approach can differentiate miRNA mutants and quantify miRNA in human plasma, tumor cells, and tissues with high sensitivity, suggesting that the target‐triggered integration of enzymes and phages holds promise for searching for new catalysts. [ABSTRACT FROM AUTHOR]

[Fe]‐hydrogenase, the third type of natural hydrogenase, is capable to heterolytically activate hydrogen molecule and transfer the resulting hydride to an unsaturated substrate, making it a promising hydrogenation catalyst. Over the last three decades, fruitful results on this enzyme have been achieved. In this review, we have summarized the major progresses about this enzyme including its structural characterisation, catalytic mechanism, cofactor biosynthesis, mimetic model development as well as artificial enzymes construction. In the meanwhile, challenges and opportunities of this enzyme and its mimetic systems in the application of synthetic chemistry and others are discussed. [ABSTRACT FROM AUTHOR]

Natural enzymes are used as special reagents for the preparation of electrochemical (bio)sensors due to their ability to catalyze processes, improving the selectivity of detection. However, some drawbacks, such as denaturation in harsh experimental conditions and their rapid de- gradation, as well as the high cost and difficulties in recycling them, restrict their practical applications. Nowadays, the use of artificial enzymes, mostly based on nanomaterials, mimicking the functions of natural products, has been growing. These so-called nanozymes present several advantages over natural enzymes, such as enhanced stability, low cost, easy production, and rapid activity. These outstanding features are responsible for their widespread use in areas such as catalysis, energy, imaging, sensing, or biomedicine. These materials can be divided into two main groups: metal and carbon-based nanozymes. The latter provides additional advantages compared to metal nanozymes, i.e., stable and tuneable activity and good biocompatibility, mimicking enzyme activities such as those of peroxidase, catalase, oxidase, superoxide dismutase, nuclease, or phosphatase. In this review article, we have focused on the use of carbon-based nanozymes for the preparation of electrochemical (bio)sensors. The main features of the most recent applications have been revised and illustrated with examples selected from the literature over the last four years (since 2020).

[Display omitted] Although it is well-accepted that iron oxide nanoparticles are considered as artificial enzymes when their surface is hydrophilic, the enzyme-like properties of iron oxide nanoparticles with hydrophobic surface coating is unexplored. This work demonstrates that hydrophobic iron oxide nanocrystals coated with a layer of oleic acid could serve as artificial enzymes when their surface is covered by a layer of ionic surfactant. Furthermore, the co-assembly of iron oxide nanocrystals and porous organic cages could modulate their enzyme-like activities. Co-assembly of iron oxide (Fe 3 O 4) nanocrystals with different size and porous organic cages (POCs) was performed by an emulsion-confined strategy to achieve hybridized Fe 3 O 4 /POCs co-assemblies. The peroxidase-mimic activity of these co-assemblies were assessed in the presence of 3, 3′, 5, 5′-Tetramethylbenzidine (TMB) and hydrogen peroxide. Finally, these co-assemblies were applied as sensors to detect glucose and hydrogen peroxide. Co-assembly of Fe 3 O 4 nanocrystals and POCs resulted in the self-assembly of Fe 3 O 4 nanoparticles into two-dimensional nanoparticle superlattices on the eight (1 1 1) facets of the octahedral POCs colloidal crystals. The unique oil-in-water (O/W) emulsion confined assembly method switches the Fe 3 O 4 nanoparticles and POC crystals from hydrophobic to hydrophilic because of the strong hydrophobic interactions. Importantly, these co-assemblies dispersed in water showed strong peroxidase-mimic activity in water despite that their surface is covered by a bilayer of aliphatic chains. Furthermore, the intrinsic enzymatic activity of the co-assemblies is highly dependent on the size of the nanocrystals, and a higher catalytic activity is achieved from a larger sized Fe 3 O 4 nanocrystal. [ABSTRACT FROM AUTHOR]

[Display omitted] Biocatalysis is an important area of modern research and is extensively explored by various industries to attain greener methods in various applications. Supramolecular interactions of short peptides have been under the scanner for developing artificial smart materials inspired from natural systems. Peptide-based artificial enzymes have been proved to show various enzyme-like activities. Therefore, immobilization of catalytic peptides on solid surfaces can be an extremely useful breakthrough for development of cost-effective catalytic formulations. In this work, a series of peptide amphiphiles (PAs) have been systematically analyzed to find the most effective catalyst with esterase like activity. The PA, containing a catalytic triad, 'Asp(Ser)His' in a branched manner, was further immobilized onto silica nanoparticles through covalent bonding method to obtain surface coated catalytic silica nanoparticles. The heterogenous catalytic formulation not only showed enhanced esterase activity than the self-assembled PA in homogenous phase, but also exceeded the activity of natural CV lipase. The catalytic formulation showed high stereoselectivity towards chiral esters. Moreover, the catalyst remained stable at higher temperature, in presence of various denaturant and retained its activity after several catalytic cycles. The ease of separation, robust nature, reusability and high stereoselectivity of the catalyst opens up the possibility of creating new generation heterogeneous catalysts for further industrial applications. [ABSTRACT FROM AUTHOR]

Natural enzymes possess remarkable catalytic activity and high substrate specificity. Many efforts have been dedicated to construct artificial enzymes with high catalytic activity. However, how to mimic the exquisite substrate specificity of a natural enzyme remains challenging because of the complexity of the enzyme structure. Here, we report artificial carboxylesterases that are specific for short chain fatty acids and were constructed via peptide self-assembly. These artificial systems have esterase-like activity rather than lipase-like activity towards p-nitrophenyl esters. The designer peptides self-assembled into nanofibers with strong β-sheet character. The extending histidine units and the hydrophobic edge of the fibrillar structure collectively form the active center of the artificial esterase. These artificial esterases show substrate specificity for short-chain acids esters. Moreover, 1-isopropoxy-4-nitrobenzene could function as a competitive inhibitor of hydrolysis of p-nitrophenyl acetate for an artificial esterase.

Rationally-engineered functional biomaterials offer the opportunity to interface with complex biology in a predictive, precise, yet dynamic way to reprogram their behaviour and correct shortcomings. Success here may lead to a desired therapeutic effect against life-threatening diseases, such as cancer. Here, we engineered "Crab"-like artificial ribonucleases through coupling of peptide and nucleic acid building blocks, capable of operating alongside and synergistically with intracellular enzymes (RNase H and AGO2) for potent destruction of oncogenic microRNAs. "Crab"-like configuration of two catalytic peptides ("pincers") flanking the recognition oligonucleotide was instrumental here in providing increased catalytic turnover, leading to ≈30-fold decrease in miRNA half-life as compared with that for " single-pincer" conjugates. Dynamic modeling of miRNA cleavage illustrated how such design enabled "Crabs" to drive catalytic turnover through simultaneous attacks at different locations of the RNA-DNA heteroduplex, presumably by producing smaller cleavage products and by providing toeholds for competitive displacement by intact miRNA strands. miRNA cleavage at the 5′-site, spreading further into double-stranded region, likely provided a synergy for RNase H1 through demolition of its loading region, thus facilitating enzyme turnover. Such synergy was critical for sustaining persistent disposal of continually-emerging oncogenic miRNAs. A single exposure to the best structural variant (Crab-p-21) prior to transplantation into mice suppressed their malignant properties and reduced primary tumor volume (by 85 %) in MCF-7 murine xenograft models. [Display omitted] [ABSTRACT FROM AUTHOR]

Glutathione peroxidase (GPx) is an important selenium-containing antioxidant enzyme in human body. The preparation of bionic GPx and the mimicry of its catalytic behavior are of great significance for the development of antioxidant drugs. At present, most of the reported biomimetic selenoenzymes based on the macromolecular are difficult to be degraded, which restricts their applications in the fields such as medical treatment, health care, and functional food. In order to solve this issue, herein, the octenyl succinic acid-modified starch (OSA starch) prepared by the esterification of waxy corn starch was used as the raw material, a new selenium-functionalized starch (Se-starch) was synthesized via the reaction of OSA starch and sodium hydrogen selenide. Such Se-starch, as a biomimetic selenoenzyme, was characterized using 1H NMR, EDS, XPS, SEM, XRD, and FT-IR. The Se-starch with a catalytic activity of 2.48 μM·min−1 showed a typical catalysis behavior of saturated kinetic and enzymology. This catalytic activity is 1.04 × 105 times higher than that of the PhSeSePh, a representative small molecule bionic GPx. The study of catalytic mechanism revealed that the octenyl succinate molecule bonded on the starch endowed it with hydrophobic micro-environments, which benefited the binding of hydrophobic substrates, and consequently increased the catalytic activity. This work not only provided a new idea for constructing natural polymers-based bionic GPx, but also offered an important theoretical basis for the development of new antioxidant drugs and functional foods. [ABSTRACT FROM AUTHOR]

[Display omitted] • CuO nanoclusters decorated on the reduced graphene oxide surface (CuONCs/rGO) offer high peroxidase-mimic catalytic activity. • TMB, H 2 O 2 , CuONCs/rGO system presence a blue color reaction. • Colorimetric assay based nanozymatic activity of CuONC/rGO was used for determination of hydrogen peroxide and ascorbic acid in real samples. Several efforts have been made to increase the nanozymatic activity of reduced Graphene Oxide (rGO). Also, the enzyme mimetic research with Nanoclusters (NCs) is in the embryo stage. For the first time, a one pot synthesis method was used successfully for preparation of CuONCs loaded r-GO (CuONCs/rGO). GO and copper sulfate were used as precursors and Bovine Serum Albumin (BSA) as the reducer and stabilizer agent. This nanocomposite possesses intrinsic peroxidase-like activity, which can catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine substrate (TMB) by H 2 O 2 to produce an intense blue color in the system. The color change was monitored by absorbance at 650 nm using a UV–vis spectrophotometer. The higher value of V max reflected the higher catalytic activity of CuONCs/rGO compared to other similar nanozymes. The increase in the blue color intensity was proportional to the H 2 O 2 concentration in the range of 3.03 × 10−7–5.7 × 10-4 M with a detection limit of 3.03 × 10-7 M. Furthermore, Ascorbic Acid (AA) could reduce the intensity of the blue color in this system. Therefore, AA was determined within the range of 3.0 × 10−7-3.8 × 10-5 M at the detection limit of 3.0 × 10-7 M. The satisfactory results were due to the synergic effect of CuONCs and rGO in the nanocomposite. [ABSTRACT FROM AUTHOR]

L-Histidine (L-His) is an essential amino acid, which is used to synthesize proteins and enzymes. The concentration of L-His in the body is controlled to regulate tissue growth and repair of tissues. In this study, a rapid and sensitive method was developed for colorimetric L-his detection using Cu2+ ions to inhibit the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB)–H2O2 system. H2O2 can oxidize TMB to oxTMB in the presence of copper, and the change in color from colorless (TMB) to blue (oxTMB) is similar to that observed in the presence of peroxidase. However, because the imidazole ring and carboxyl group of L-His can coordinate with Cu2+ ions to form stable L-His–Cu2+ complexes, the color of the TMB–H2O2 solution remains unchanged after the addition of L-His. Therefore, because L-His effectively hinders the colorimetric reaction of TMB with H2O2, this assay can be used to quantitatively determine the concentration of L-His in samples. Under optimized conditions, our colorimetric sensor exhibited two linear ranges of 60 nM to 1 μM and 1 μM to 1 mM for L-His detection and a detection limit of 50 nM (S/N = 3); furthermore, the assay can be performed within 20 min. Moreover, the proposed assay was used to determine the concentration of L-His in urine samples, suggesting that this convenient and label-free colorimetric method presents promising applications in bioanalytical chemistry and clinical diagnosis.

Nanozymes own striking merits, including high enzyme-mimicking activity, good stability, and low cost. Due to the powerful and distinguished functions, nanozymes exhibit widespread applications in the field of biosensing and immunoassay, attracting researchers in various fields to design and engineer nanozymes. Recently, nanozymes have been innovatively used to bridge nanotechnology with analytical techniques to achieve the high sensitivity, specificity, and reproducibility. However, the applications of nanozymes in food applications are seldom reviewed. In this review, we summarize several typical nanozymes and provide a comprehensive description of the history, principles, designs, and applications of nanozyme-based analytical techniques in food contaminants detection. Based on engineering and modification of nanozymes, the food contaminants are classified and then discussed in detail via discriminating the roles of nanozymes in various analytical methods, including fluorescence, colorimetric and electrochemical assay, surface-enhanced Raman scattering, magnetic relaxing sensing, and electrochemiluminescence. Further, representative examples of nanozymes-based methods are highlighted for contaminants analysis and inhibition. Finally, the current challenges and prospects of nanozymes are discussed.

Catalyzing biochemical reactions with enzymes and communicating with neighboring cells via chemical signaling are two fundamental cellular features that play a critical role in maintaining the homeostasis of organisms. Herein, we present an artificial enzyme (AE) facilitated signal transfer between artificial cells (ACs) and mammalian HepG2 cells. We synthesize metalloporphyrins (MPs) based AEs that mimic cytochrome P450 enzymes (CYPs) to catalyze a dealkylation and a hydroxylation reaction, exemplified by the conversion of resorufin ethyl ether (REE) to resorufin and coumarin (COU) to 7‐hydroxycoumarin (7‐HC), respectively. The AEs are immobilized in hydrogels to produce ACs that generate the two diffusive fluorophores, which can diffuse into HepG2 cells and result in dual intracellular emissions. This work highlights the use of AEs to promote AC to mammalian signal transfer, which opens up new opportunities for integrating the synthetic and living world with a bottom‐up strategy. [ABSTRACT FROM AUTHOR]

Artificial catalyst studies were always stayed at the kinetics investigation level, in this work bioactivity of designed catalyst were shown by the induction of biomineralization of the cells, indicating the possible use of enzyme mimics for biological applications. The development of artificial enzymes is a continuous quest for the development of tailored catalysts with improved activity and stability. Understanding the catalytic mechanism is a replaceable step for catalytic studies and artificial enzyme mimics provide an alternative way for catalysis and a better understanding of catalytic pathways at the same time. Here we designed an artificial catalyst model by decorating peptide nanofibers with a covalently conjugated catalytic triad sequence. Owing to the self-assembling nature of the peptide amphiphiles, multiple action units can be presented on the surface for enhanced catalytic performance. The designed catalyst has shown an enzyme-like kinetics profile with a significant substrate affinity. The cooperative action in between catalytic triad amino acids has shown improved catalytic activity in comparison to only the histidine-containing control group. Histidine is an irreplaceable contributor to catalytic action and this is an additional reason for control group selection. This new method based on the self-assembly of covalently conjugated action units offers a new platform for enzyme investigations and their further applications. Artificial catalyst studies always stayed at the kinetics investigation level, in this work bioactivity of the designed catalyst was shown by the induction of biomineralization of the cells, indicating the possible use of enzyme mimics for biological applications. [ABSTRACT FROM AUTHOR]

• CuBSA (Cu-bovine serum albumin nanoenzymes) was prepared by binding BSA to Cu2+. • CuBSA has a natural superoxide dismutase-like structure and excellent antioxidant capacity. • CuBSA has good bactericidal properties and is biocompatible. • Antimicrobial and antioxidant capabilities were obtained for composite films containing CuBSA. As monofunctional packaging becomes less able to satisfy the need for environmentally friendly convenience, functionalized packaging is becoming more and more significant in food applications. In this study, a biomimetic artificial nano-enzyme, bovine serum albumin (BSA) chelated with copper ions (CuBSA), was constructed by imitating the structure of natural superoxide dismutase (SOD). This novel CuBSA metallo-nanoenzyme possesses distinct SOD-like enzyme activity, antibacterial capabilities, as well as thermal stability and biocompatibility. With CuBSA as excellent filler, the carrageenan-based nanocomposite films were obtained, showing excellent performance in retarding enzymatic browning and inhibiting microbial attack on fresh-cut apples and figs, even stored at room temperature. More importantly, this new composite film is low-cost and simple to be synthesized for large-scale use. [ABSTRACT FROM AUTHOR]

Development of hetero-atom rich porous organic polymers (POPs) in facile and easy accessible methods are of significant importance to broad application potentials and enrich diversity of such materials. Here, a bidirectional adjustment strategy, starting with amino and aldehyde monomers, concurrently, was used for the rational preparation of N-rich aminal-linked POPs with customized structure and function. Five novel ferrocene-based aminal-linked POPs, were facilely fabricated via the one-pot catalyst-free Schiff base polycondensation between the 1,1′-Ferrocene dicarboxaldehyde and different types of triazine-bearing monomers with diverse geometrical features and functions (Porphyrin, cationic viologen, Ferrocene, 1,4,7,10-tetraazacyclododecane, and benzyl). The concurrent introduction of Ferrocene (redox-active) and triazine-Porphyrin (photoactive) endowed remarkable mimicking peroxidase-like activity and excellent photothermal and photodynamic activity with Fc-TDPP, which could be used as a broad spectrum fungicide, exerting photothermal enhanced photodynamic and enzyme antibacterial therapy. Notably, in vitro and in vivo experiments confirmed Fc-TDPP could not only kill S. aureus and E. coli quickly and efficiently, but also significantly accelerate the repairing of open wounds with S. aureus -infection. The as-proposed strategy are available for the low-cost constructing N-rich POPs with specific structure and functions targeted for wide potential applications in various fields. • Bidirectionally regulated strategy is adopted to develop porous PPANs. • Ferrocene-based aminal-linked PPANs with POD enzyme activity is prepared. • Fc-TDPP amalgamated the Ferrocene and Porphyrin repeated unites. • Fc-TDPP featured remarkable POD activity and excellent photo activity. • Fc-TDPP exerted photothermal-amplified synergistic antibacterial therapy. [ABSTRACT FROM AUTHOR]

[Display omitted] • Homopolymers and copolymers with histidine COOH, CONH 2 , and NH 2 were synthesized. • The polymers were incubated with bovine serum albumin and analyzed by SDS-PAGE. • Polymers with histidine COOH cleaved bovine serum albumin at pH 4.2 and pH 7.4. • Several polymers with specific histidine densities showed activity at pH 8.0. • Polymers with specific COOH density exhibited varying digestion patterns based on pH. Artificial enzymes with serine, aspartic acid, and histidine that mimic the catalytic triad of serine proteases have been studied. However, they were mainly investigated for their cleavage activity on low molecular-weight esters and amides, and there has been a lack of knowledge about their protein cleavage activity. We previously found that not only ternary polyacrylamides with serine, aspartic acid, and histidine but also homo-polyacrylamides with a single type of amino acid cleaved bovine and human serum albumins. These results suggested that the carboxy group, a common functional group in active polymers, may be involved in the expression of activity. In this study, we synthesized histidine polymers in which the carboxy group was changed to a carboxamido or amino group and investigated the relationships between structure and activity. Histidine homopolymers and histidine-acrylamide copolymers were incubated with bovine serum albumin at 37 °C for one week under different pH conditions and then analyzed by sodium dodecyl-sulfate polyacrylamide gel electrophoresis. In the case of histidine homopolymers, the carboxy-type homopolymers were active under weakly acidic to neutral conditions, while the carboxamido- and amino-type homopolymers were not active regardless of liquid properties. In the case of histidine-acrylamide copolymers, their activity was essentially the same as that of each type of histidine homopolymer, but for all types of copolymers, activity appeared under weakly basic conditions when the histidine monomer units were of a specific density. The carboxy-type copolymers with dual-mode activity showed different degradation patterns of bovine serum albumin under acidic and basic conditions. The structural features common to the active homopolymers and copolymers suggested that the carboxy group contributes to the activity under weakly acidic to neutral conditions, while the imidazole group of the histidine side chain and its density contribute to the activity under weakly basic conditions. [ABSTRACT FROM AUTHOR]

The conversion of Kraft lignin in plant biomass into renewable chemicals, aiming at harvesting aromatic compounds, is a challenge process in biorefinery. Comparing to the traditional chemical methods, enzymatic catalysis provides a gentle way for the degradation of lignin. Alternative to natural enzymes, artificial enzymes have been received much attention for potential applications. We herein achieved the biodegradation of Kraft lignin using an artificial peroxidase rationally designed in myoglobin (Mb), F43Y/T67R Mb, with a covalently linked heme cofactor. The artificial enzyme of F43Y/T67R Mb has improved catalytic efficiencies at mild acidic pH for phenolic and aromatic amine substrates, including Kraft lignin and the model lignin dimer guaiacylglycerol-β-guaiacyl ether (GGE). We proposed a possible catalytic mechanism for the biotransformation of lignin catalyzed by the enzyme, based on the results of kinetic UV-Vis studies and UPLC-ESI-MS analysis, as well as molecular modeling studies. With the advantages of F43Y/T67R Mb, such as the high-yield by overexpression in E. coli cells and the enhanced protein stability, this study suggests that the artificial enzyme has potential applications in the biodegradation of lignin to provide sustainable bioresource.

Resistant bacteria have become a global threat. Even if bacteria are killed, their carried drug‐resistant genes can remain in the environment and spread to other microbes via horizontal gene transfer. Development of antimicrobial materials with intrinsic gene break down activity can prevent the dissemination of released drug‐resistant genes from the dead bacteria. Herein, imidazolium type poly(ionic liquid) (PIL)/cerium (IV) ion‐based electrospun nanofibrous membranes (PIL‐Ce) are synthesized. The effects of PIL and Ce moieties on the antimicrobial properties against Gram‐negative Escherichia coli and kanamycin‐resistant E. coli, and Gram‐positive Staphylococcus aureus and methicillin‐resistant S. aureus (MRSA), as well as deoxyribonuclease‐mimic activities to the drug‐resistant genes of KanR (E. coli) and mecA (MRSA) are investigated. The Ce‐containing PIL membranes show the high efficiencies to eradicate bacteria and disintegrate drug‐resistant genes. A wound treatment test using MRSA infected mice as the model further demonstrate that PIL‐Ce membranes combine both antibacterial and DNase‐mimic properties, and may have the potential application as a new "green" wound dressing to block the drug resistance spread in a clinical setting. [ABSTRACT FROM AUTHOR]

The authors describe a rapid enzyme-free colorimetric assay for food- and water-borne pathogens by using the multi-functional MnO2-doped magnetic ferrite nanoparticles (MCDs-MnO2 NPs). These nanoparticles not only can recognize, absorb, and separate the analyte from the matrix efficiently but also can directly catalyze the oxidation of TMB into a blue colored product without H2O2. In the presence of target, the nanoparticles preferentially bind to the target surface and the interaction between nanoparticles and TMB can be blocked, providing turn-off sensing of bacteria. By combining the superior capture efficiency of magnetic beads with the high catalytic activity of the enzyme mimic, the turn-off colorimetric assay can detect the gram-positive bacterium and the gram-negative bacterium by the naked eye at a low detection limit (102 cfu mL−1) with a wide line arrange from 10 to 106 cfu mL−1. With the advantage of simplicity, sensitivity, and specificity, this proposed approach showed promise in rapid instrumental and on-site visual detection of bacteria for determination of water contamination. [ABSTRACT FROM AUTHOR]

Streptavidin (SA), and other related proteins, has been isolated from a wide range of organisms, including bacteria, fungi, frogs, fish, and birds. Although their original function is not well understood, they have found an important place in biotechnology based on their unique ability to bind biotin molecules with high affinity and specificity. The SA–biotin interaction is robust and easy to incorporate into different designs, and as such, it is used when reliable molecule interaction is needed under poorly controlled experimental conditions. There are continued efforts to engineer these proteins to modulate their size, valency, and affinity, since the optimum molecular properties vary depending on individual applications. This review will describe recent developments in streptavidin engineering to meet these requirements, including those that form novel oligomeric states, e.g., a monomer, have fewer functional biotin-binding sites, or bind biotin with reduced affinity. We also examine various reported applications of both natural or engineered SA constructs in cell biology, biochemistry, genetics, synthetic chemistry, cancer therapy, drug delivery, and nanotechnology to illustrate the breadth of modern science that is advanced by the endogenous and engineered SA–biotin interactions. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Hemin is an eco-friendly enzymatic catalyst with unique photochemical behavior. • Stable biomimetic hemin-bismuth tungstate (HBWO) composites were synthesized. • 2D HBWO showed faster charge carriers transfer and higher light absorption. • Hemin acts as an electron shuttle and plays an important role in the oxygen transfer. • Synthesized HBWO exhibits nice binding affinities and high photocatalytic activity. Abstract Highly-efficient and eco-friendly materials and technologies are urgently needed to meet the requirements of nowadays green development. Photocatalysis with using solar energy and enzymatic catalysis with eco-friendly nature are effective alternatives to address the problem. Notably, beneficial use of the synergistic effect of artificial enzyme and advanced photocatalyst has attracted wide attention. This work presents a biomimetic photocatalytic material, two-dimensional (2D) biomimetic hemin-bismuth tungstate (HBWO). Stable HBWO composites formed by immobilization of monomeric hemin on 2D bismuth tungstate layer, exhibit high photocatalytic performance, better than that of pure 2D bismuth tungstate and unsupported hemin. HBWO shows layered structure with the interlayer spacing at ˜0.35 nm. In the photocatalytic process, hemin can not only act as an electron shuttle, also play an important role in oxygen transfer. Additionally, the synthesized HBWO composites exhibit nice binding affinities and high photocatalytic activity in tetracycline degradation. It is anticipated that beneficial use of synergistic effect of artificial enzyme and photocatalyst via HBWO composites can be a promising eco-friendly and efficient solution for addressing the environmental crisis. [ABSTRACT FROM AUTHOR]

Notorious bacterial biofilms are becoming severe threats to public health worldwide. As the important component in biofilm extracellular polymeric substances (EPS), extracellular DNA (eDNA) has been manifested to connect different EPS components and bacteria together, leading biofilms hard to eliminate. Herein a series of MOF/Ce-based nanozymes with deoxyribonuclease (DNase) and peroxidase mimetic activities have been designed and synthesized for combating biofilms. The cerium (IV) complexes (DNase mimics) are capable of hydrolyzing eDNA and disrupting established biofilms, while the MOF with peroxidase-like activity can kill bacteria exposed in dispersed biofilms in the presence of H 2 O 2. This can avoid the recolonization of bacteria and recurrence of biofilms. Given the fact that single-modal antibacterial agent is difficult to drastically eradicate biofilms, the marriage of two kinds of nanozymes is a rational strategy to acquire enhanced performance in combating biofilms. Besides, the utilization of nanozymes circumvents drawbacks of natural enzymes which are costly and vulnerable. Further studies have demonstrated that this kind of artificial enzyme with dual enzyme-mimetic activities can penetrate the biofilms, and inhibit bacterial biofilm formation intensively. Consistently, in vivo anti -biofilm application in treating subcutaneous abscess exhibits commendable wound healing and admirable bactericidal effect. To the best of our knowledge, it is the first time to devise an integrated nanozyme based on the peroxidase-like activity of MOF to eliminate biofilms and kill bacteria on site. This work may promote the application of MOF in the antibacterial field. [ABSTRACT FROM AUTHOR]

Outcomes of chemical reactions are generally dominated by the intrinsic reactivities of reaction partners, but enzymes frequently override such constraints to transform less reactive molecules in the presence of more reactive ones. Despite the attractiveness of such catalysis, it is difficult to build synthetic catalysts with these features. Micellar imprinting is a powerful method to create template‐complementary binding sites inside protein‐sized water‐soluble nanoparticles. When a photocleavable functional monomer was used to bind two phosphonate/phosphate templates as transition‐state analogues, active sites with predetermined size and shape were formed inside doubly cross‐linked micelles through molecular imprinting. Postmodification replaced the binding group with a catalytic pyridyl group, forming highly selective artificial esterases. The catalysts displayed enzyme‐like kinetics and turnover numbers that were in the hundreds. The selectivity of the catalysts, derived from the substrate‐complementary imprinted active sites, enabled transformation of less reactive esters in the presence of more reactive ones. [ABSTRACT FROM AUTHOR]

Abstract To develop a highly sensitive colorimetric detection method for the diabetes early diagnosis by determining the glucose in urine instead of blood can avoid the painful blood collection and risks of cross infection. In this paper, novel artificial enzyme mimics were formed by loading bimetallic nanoparticle Fe Pd on the surface of reduced graphene (rGO). Also, we proposed a Fe Pd/rGO coupled with portable paper sensor for the detection of glucose in urine. The results indicated that urine glucose can be sensitively detected in a wide range of 1–200 μM with a limit of detection (LOD) of 1.76 μM. Most important, the color difference along with the increase of urine glucose concentration can be easily distinguished by naked eyes, which is important to its practical usage in screening and diagnosis of diabetes. Furthermore, the reason of the high sensitivity of Fe Pd/rGO towards glucose was investigated in detail via various probing experiments. Fe Pd/rGO has an artificial enzyme mimic activity, which can catalyze O 2 and generate H 2 O 2 from glucose oxidation. The electron transfer between Fe Pd and H 2 O 2 will produce •OH that can oxidize terephthalic acid (TMB) by emitting a blue color. The findings in this study provide a promising alternative for the early screening and diagnosis of diabetes. Graphical abstract Hydrogen peroxide, as the product of glucose oxidation, was adsorbed and catalytic decomposition to form Free radicals (•OH) on the surface of Fe Pd/rGO nanocomposite via the partial electron exchange interaction. The strong oxidation performance of •OH can promote catalytic oxidation of TMB so as to improve sensitivity of glucose detection. Image 1 Highlights • Highly sensitive Fe Pd/rGO nanosensor were formed to detect glucose concentration. • The formation of •OH provide excellent glucose detection performance for Fe Pd/rGO nanosensor. • Sensitive visual detection of urine glucose was realized with portable paper sensor. [ABSTRACT FROM AUTHOR]

Abstract Listeria monocytogenes (L. monocytogenes) is one of the most common food-borne pathogens. The authors describe a sensitive and reliable multicolorimetric assay for L. monocytogenes using a sensing system based on TMB2+ etching of gold nanorods. Apt-MNP was used as the capture probe, and IgY-BSA-MnO 2 NPs was chosen as an oxidase-like nano-artificial enzyme to oxidize TMB to generate TMB2+. Under the optimized conditions, the longitudinal shift of localized surface plasmon resonances had a linear correlation with the L. m onoc ytogenes concentration in the range between 10 to 106 cfu mL−1. Meanwhile, the sensing system can generate vivid color responses as colorful as a rainbow, and the limit of detection is as low as 10 cfu mL−1 at a glance. Recoveries ranging from 97.4 to 101.3% are found when analyzing spiked food samples without pre-enrichment. In our perception, it shows promise in rapid instrumental and on-site visual detection of L. monocytogenes. Graphical abstract Image 1 Highlights • A high-resolution multicolorimetric assay is developed for bare-eye detection of L. monocytogenes. • The proposed assay exhibited high selectivity for rapid detection of L. monocytogenes with a detection limit of 10 cfu mL−1. • The proposed assay was applied to analysis of L. monocytogenes in pork samples without pre-enrichment. [ABSTRACT FROM AUTHOR]

In this report, the streptavidin-biotin technology was applied to enable organocatalytic aldol addition. By attaching pyrrolidine to the valeric motif of biotin and introducing it to streptavidin (Sav), a protein-based organocatalytic system was created, and the aldol addition of acetone with p-nitrobenzaldehyde was tested. The conversion of substrate to product can be as high as 93%. Although the observed enantioselectivity was only moderate (33:67 er), further protein engineering efforts can be included to improve the selectivity. These results have proven the concept that Sav can be used to host stereoselective aldol addition.

The degradation of organophosphorous nerve agents is of primary concern due to the severe toxicity of these agents. Based on the active center of organophosphorus hydrolase (OPH), a bimetallic nuclear ligand, (5-vinyl-1,3-phenylene)bis(di(1H-imidazol-2-yl) methanol) (VPIM), was designed and synthesized, which contains four imidazole groups to mimic the four histidines at OPH active center. By grafting VPIM on graphene oxide (GO) surface via polymerization, the VPIM-polymer beads@GO was produced. The obtained OPH mimics has an impressive activity in dephosphorylation reactions (turnover frequency (TOF) towards paraoxon: 2.3 s −1 ). The synergistic catalytic effect of the bimetallic Zn 2+ nuclear center and carboxyl groups on surface of GO possibly contributes to the high hydrolysis on organophosphate substrate. Thus, a biomimetic catalyst for efficient degradation of some organophosphorous nerve agent simulants, such as paraoxon and chlorpyrifos, was prepared by constructing catalytic active sites. The proposed mechanism and general synthetic strategy open new avenues for the engineering of functional GOs for biomimetic catalysts. [ABSTRACT FROM AUTHOR]

The search for a perfect model to mimic the properties of the selenoenzyme glutathione peroxidase (GPx) has inspired great interest. Rational design and redesign of the structure–function relationship has become an indispensable technique. In this report, the active site of selenosubtilisin was successfully rebuilt by transferring the catalytically essential residue selenocysteine (Sec) to the edge of the substrate-binding pocket of the enzyme by artificial manipulation. Founding on computer-aided molecular simulation, the amino acid residue at position 63 (Ser in the wild-type enzyme) was selectively replaced with Sec using a cysteine auxotrophic expression system. The novel seleno 63 -subtilisin E gave a prominent 100-fold higher efficiency than the original seleno 221 -subtilisin E for GPx activity. Moreover, this seleno 63 -subtilisin E also had efficient hydrolase activity. [ABSTRACT FROM AUTHOR]

Today, nano-medicine promotes new therapeutics and diagnostics tools, including sensing of biomolecules as a biosensor, cancer chemotherapy and drug or gene delivery. Because of small size and biocompatibility of gold nanoparticles (GNPs), they become a good candidate for biological application. Also, thanks to their biological and chemical properties, they can mimic function of some enzymes including super oxide dismutase (SOD), esterase, etc. Also, biomaterials and bioengineering have grown so fast since the last decade for many therapeutic applications such as tissue regeneration. Among these cutting edge technology, nanomaterials find the way to becoming a very powerful tool for using in many fields of researchers including biosensing, gene therapy and chemotherapy. In this review, we focused on some biological applications of GNPs in biology and medicine. [ABSTRACT FROM AUTHOR]

l -Proline is a bifunctional versatile organocatalyst that could promote a variety of useful transformations. Some passive and dynamic interactions between this simple amino acid and different substrates, which are necessary to enzymatic reactions, have given it “the simplest enzyme” title. Herein we presented the first report on the synthesis of magnetic bifunctional l -proline as an artificial enzyme without requiring any protection/deprotection steps according to an operationally simple process. This magnetic nano-biocatalyst is a promising catalyst that in a case study was successfully applied for the synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles in the 70–99% and 60–90% yields respectively, which it could be extended to the variety of l -proline-based organic transformations. The synergic effect of bifunctional l -proline shell as catalytic active site and magnetite nanoparticles core, which could function as protein mimics endow it high efficiency, versatility, recoverability, reusability and good turnover frequency, which are necessary characters for artificial enzymes’ designing. [ABSTRACT FROM AUTHOR]

A visual colorimetric microfluidic paper-based analytical device (μPAD) was constructed following the direct synthesis of enzyme-inorganic hybrid nanomaterials on the paper matrix. An inorganic solution of MnSO 4 and KH 2 PO 4 containing a diluted enzyme (glucose oxidase, GOx) was subsequently pipetted onto cellulose paper for the in situ growth of GOx@Mn 3 (PO 4 ) 2 hybrid functional materials. The characterization of the morphology and chemical composition validated the presence of hybrid materials roots in the paper fiber, while the Mn 3 (PO 4 ) 2 of the hybrid provided both a surface for enzyme anchoring and a higher peroxidase-like catalytic activity as compared to the Mn 3 (PO 4 ) 2 crystal that was synthesized without enzyme modulation. This new approach for the in situ growth of an enzyme-inorganic hybrid on a paper matrix eliminates centrifugation and the dry process by casting the solution on paper. The sensing material loading was highly reproducible because of the accuracy and stability of pipetting, which eventually contributed to the reliability of the μPAD. The self-assembled natural and artificial enzyme hybrid on the μPADs specifically detected glucose from a group of interferences, which shows great specificity using this method. Moreover, the colorimetric signal exhibited detection limitation for glucose is 0.01 mM, which lies in the physiological range of glucose in biological samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • Polyacrylamides functionalized with amino acids were synthesized. • Some polymers showed cleavage activity against bovine and human serum albumins. • The cleavage profiles of the active polymers differed from those of α-chymotrypsin. • At 50 °C, α-chymotrypsin lost activity, but the polymer showed better protein cleavage. Polyacrylamides with various compositions of serine, aspartic acid, and histidine, which are the amino acids involved in the catalytic triad of natural serine protease chymotrypsin, were synthesized and their protein cleavage activity was investigated. SDS-PAGE analysis showed that some of the synthesized ternary copolymers showed cleavage activity against bovine and human serum albumins. Polyacrylamides incorporating a single type of amino acid were also able to cleave the protein substrates. These homopolymers exhibited unique cleavage profiles and pH and temperature sensitivities that differed from those of α-chymotrypsin. The results indicate the potential of polymers functionalized with amino acids as proteolytic artificial enzymes. [ABSTRACT FROM AUTHOR]

The anticancer efficacy of a supramolecular complex that was used as an artificial enzyme against multi-drug-resistant cancer cells was confirmed. A complex of diethylaminoethyl–dextran–methacrylic acid methylester copolymer (DDMC)/paclitaxel (PTX), obtained with PTX as the guest and DDMC as the host, formed a nanoparticle 50–300 nm in size. This complex is considered to be useful as a drug delivery system (DDS) for anticancer compounds since it formed a stable polymeric micelle in water. The resistance of B16F10 melanoma cells to PTX was shown clearly through a maximum survival curve. Conversely, the DDMC/PTX complex showed a superior anticancer efficacy and cell killing rate, as determined through a Michaelis–Menten-type equation, which may promote an allosteric supramolecular reaction to tubulin, in the same manner as an enzymatic reaction. The DDMC/PTX complex showed significantly higher anticancer activity compared to PTX alone in mouse skin in vivo. The median survival times of the saline, PTX, DDMC/PTX4 (particle size 50 nm), and DDMC/PTX5 (particle size 290 nm) groups were 120 h (treatment (T)/control (C), 1.0), 176 h (T/C, 1.46), 328 h (T/C, 2.73), and 280 h (T/C, 2.33), respectively. The supramolecular DDMC/PTX complex showed twice the effectiveness of PTX alone (p < 0.036). Above all, the DDMC/PTX complex is not degraded in cells and acts as an intact supramolecular assembly, which adds a new species to the range of DDS.

Vibrio parahaemolyticus ( V. parahaemolyticus) is one of the most common food-borne pathogens. The authors describe a rapid colorimetric assay for V. parahaemolyticus that is based on a combination of a magnetic bead-based sandwich immunoassay and signal amplification via an enzmye mimic. MnO nanoparticles are used as an artificial oxidase that oxidizes 3,3′,5,5′-tetramethylbenzidine in the presence of oxygen to form a blue (and readily visible) product with an absorption maximum at 652 nm. By combining the superior capture efficiency of magnetic beads with the high catalytic activity of the enzmye mimic, this method can detect V. parahaemolyticus concentration in the range between 10 to 10 cfu·mL without pre-enrichment, and the limit of detection is as low as 10 cfu·mL. Recoveries ranging from 87.5% to 106.0% are found when analyzing spiked oyster samples. The assay is rapid, sensitive, and specific and specific. In our perception, it shows promise in rapid instrumental and on-site visual detection of V. parahaemolyticus. [ABSTRACT FROM AUTHOR]