A comparison increasing the photodegradation power of a Ag/g-C3N4 /CoNi-LDH nanocomposite: Photocatalytic activity toward water treatment.

For environmental applications, it is crucial to rationally design and synthesize photocatalysts with positive exciton splitting and interfacial charge transfer. Here, a novel Ag-bridged dual Z-scheme Ag/g-C3N4/CoNi-LDH plasmonic heterojunction was successfully synthesized using a simple method, with the goal of overcoming the common drawbacks of traditional photocatalysts such as weak photoresponsivity, rapid combination of photo-generated carriers, and unstable structure. These materials were characterized by XRD, FT-IR, SEM, TEM UV-Vis/DRS, and XPS to verify the structure and stability of the heterostructure. The pristine LDH, g-C3N4, and Ag/g-C3N4/CoNi-LDH composite were investigated as photocatalysts for water remediation, an environmentally motivated process. Specifically, the photocatalytic degradation of tetracycline was studied as a model reaction. The performance of the supports and composite catalyst were determined by evaluating both the degradation and adsorption phenomenon. The influence of several experimental parameters such as catalyst loading, pH, and tetracycline concentration were evaluated. The current study provides important data for water treatment and similar environmental protection applications.

Protonated carbon nitride for rapid photocatalytic sterilization via synergistic oxidative damage and physical destruction.

Photocatalytic disinfection is an eco-friendly strategy for countering bacterial pollution in aquatic environments. Numerous strategies have been devised to facilitate the generation of reactive oxygen species (ROS) within photocatalysts, ultimately leading to the eradication of bacteria. However, the significance of the physical morphology of photocatalysts in the context of sterilization is frequently obscured, and the progress in the development of physical-chemical synergistic sterilization photocatalysts has been relatively limited. Herein, graphitic carbon nitride (g-C3N4) is chemically protonated to expose more sharp edges. PL fluorescence and EIS results indicate that the protonation can accelerate photogenerated carrier separation and enhance ROS production. Meanwhile, the sharp edges on the protonated g-C3N4 facilitate the physical disruption of cell walls for further promoting oxidative damage. Protonated C3N4 demonstrated superior bactericidal performance than that of pristine g-C3N4, effectively eliminating Escherichia coli within 40 minutes under irradiation. This work highlights the significance of incorporating physical and chemical synergies in photocatalyst design to enhance the disinfection efficiency of photocatalysis.

Mn/S diatomic sites in C3N4 to enhance O2 activation for photocatalytic elimination of emerging pollutants.

Oxygen activation leading to the generation of reactive oxygen species (ROS) is essential for photocatalytic environmental remediation. The limited efficiency of O2 adsorption and reductive activation significantly limits the production of ROS when employing C3N4 for the degradation of emerging pollutants. Doping with metal single atoms may lead to unsatisfactory efficiency, due to the recombination of photogenerated electron-hole pairs. Here, Mn and S single atoms were introduced into C3N4, resulting in the excellent photocatalytic performances. Mn/S-C3N4 achieved 100% removal of bisphenol A, with a rate constant 11 times that of pristine C3N4. According to the experimental results and theoretical simulations, S-atoms restrict holes, facilitating the photo-generated carriers' separation. Single-atom Mn acts as the O2 adsorption site, enhancing the adsorption and activation of O2, resulting the generation of ROS. This study presents a novel approach for developing highly effective photocatalysts that follows a new mechanism to eliminate organic pollutants from water.

Isonitrile biosynthesis by non-heme iron(II)-dependent oxidases/decarboxylases.

The isonitrile group is a compact, electron-rich moiety coveted for its commonplace as a building block and bioorthogonal functionality in synthetic chemistry and chemical biology. Hundreds of natural products containing an isonitrile group with intriguing bioactive properties have been isolated from diverse organisms. Our recent discovery of a conserved biosynthetic gene cluster in some Actinobacteria species highlighted a novel enzymatic pathway to isonitrile formation involving a non-heme iron(II) and α-ketoglutarate-dependent dioxygenase. Here, we focus this chapter on recent advances in understanding and probing the biosynthetic machinery for isonitrile synthesis by non-heme iron(II) and α-ketoglutarate-dependent dioxygenases. We will begin by describing how to harness isonitrile enzymatic machinery through heterologous expression, purification, synthetic strategies, and in vitro biochemical/kinetic characterization. We will then describe a generalizable strategy to probe the mechanism for isonitrile formation by combining various spectroscopic methods. The chapter will also cover strategies to study other enzyme homologs by implementing coupled assays using biosynthetic pathway enzymes. We will conclude this chapter by addressing current challenges and future directions in understanding and engineering isonitrile synthesis.

Manipulating Charge Distribution of Graphitic Carbon Nitride for Boosting NIR-II Light-Activated Reactive Oxygen Species Generation.

Structure engineering is of great importance to enhance the carrier separation efficiency of multiphoton absorption (MPA) materials for near-infrared (NIR) light-driven reactive oxygen species (ROS) generation. In this study, the MPA-responsive potassium/cyano group-functionalized graphitic carbon nitride was investigated, demonstrating charge redistribution and improved carrier separation efficiency by density functional theory calculations and experimental results. With various types of boosted ROS generation under UV-vis or NIR-II light irradiation, the potassium/cyano group-functionalized graphitic carbon nitride could achieve efficient multiphoton photodynamic therapy after reducing the particle size. This study developed a simple strategy to manipulate charge distribution for booting NIR light-activated ROS generation in efficient multiphoton photodynamic therapy.

Synthesis, molecular docking study, MD simulation, ADMET, and drug likeness of new thiazolo[3,2-a]pyridine-6,8-dicarbonitrile derivatives as potential anti-diabetic agents.

There are numerous uses for the pharmacological effects of thiazolo-pyridine and its derivatives. The main objective of the study was to synthesis 10 novel derivatives of thiazolo[3,2-a] pyridine-6,8-dicarbonitrile with a 22-78% yield, with a focus on their potential anti-diabetic properties. We investigated the interactions between these compounds and the enzyme α-amylase through an in silico study involving molecular docking. According to the docking analysis results, the resulting compounds had advantageous inhibitory properties. With a docking score of -7.43 kcal/mol against the target protein, compound 4e performed best. The stability root-mean-square deviation (RMSD) showed that the complex stabilizes after 25 ns and with minor perturbation at 80. The RMSF values of the ligand-protein complex indicate that the following residues have interacted with compound 4e during the MD simulation: Trp58, Trp59, Tyr62, Gln63, His101, Val107, lle148, Asn152, Leu162, Thr163, Gly164, Leu165, Asp197, Ala198, Asp 236, Leu237, His299, Asp300, and His305. Moreover, the pharmacokinetic and drug-like properties of the synthesized derivatives of 2-arylamino-dihydroindeno[1,2-b] pyrrol-4(1H)-one suggest that they have the potential to be effective inhibitors of α-amylase and should be considered for further research. Nevertheless, it is crucial to ascertain the in vivo and in vitro effectiveness of these compounds through biochemical and structural investigations.

Association mechanism of bicalutamide and human serum albumin for potential clinical implications.

The binding mechanism of molecular interaction between bicalutamide and human serum albumin (HSA) in a pH 7.4 phosphate buffer was studied using various spectroscopic techniques in combination with molecular modeling. Fluorescence data revealed that the fluorescence quenching of HSA by bicalutamide was a static quenching procedure. The binding constants and number of binding sites were evaluated at different temperatures. The thermodynamic parameters, ΔH and ΔS, were calculated to be 4.30 × 104 J·mol-1 and 245 J·mol-1·K-1, respectively, suggesting that the binding of bicalutamide to HSA was driven mainly by hydrophobic interactions and hydrogen bonds. The displacement studies indicated neither Sudlow's site I nor II but subdomain IB as the main binding site for bicalutamide on HSA. The binding distance between bicalutamide and HSA was determined to be 3.54 nm based on the Förster theory. Analysis of circular dichroism, synchronous, and 3D fluorescence spectra demonstrated that HSA conformation was slightly altered in the presence of bicalutamide.

Enhancement of effluent degradation by zinc oxide, carbon nitride, and carbon xerogel trifecta on brass monoliths.

In recent years, heterogeneous photocatalysis has emerged as a promising alternative for the treatment of organic pollutants. This technique offers several advantages, such as low cost and ease of operation. However, finding a semiconductor material that is both operationally viable and highly active under solar irradiation remains a challenge, often requiring materials of nanometric size. Furthermore, in many processes, photocatalysts are suspended in the solution, requiring additional steps to remove them. This can render the technique economically unviable, especially for nanosized catalysts. This work demonstrated the feasibility of using a structured photocatalyst (ZnO, g-C3N4, and carbon xerogel) optimized for this photodegradation process. The synthesized materials were characterized by nitrogen adsorption and desorption, X-ray diffraction (XRD), and diffuse reflectance spectroscopy (DRS). Adhesion testing demonstrated the efficiency of the deposition technique, with film adhesion exceeding 90%. The photocatalytic evaluation was performed using a mixture of three textile dyes in a recycle photoreactor, varying pH (4.7 and 10), recycle flow rate (2, 4, and 6 L h-1), immobilized mass (1, 2, and 3 mg cm-2), monolith height (1.5, 3.0, and 4.5 cm), and type of radiation (solar and visible artificials; and natural solar). The structured photocatalyst degraded over 99% of the dye mixture under artificial radiation. The solar energy results are highly promising, achieving a degradation efficiency of approximately 74%. Furthermore, it was possible to regenerate the structured photocatalyst up to seven consecutive times using exclusively natural solar light and maintain a degradation rate of around 70%. These results reinforce the feasibility and potential application of this system in photocatalytic reactions, highlighting its effectiveness and sustainability.

Multivalent Pt/Ti3C2Tx Nanocomposite-Based Immunochromatographic Sensor for Colorimetric/Temperature/Pressure Trimodal Detection.

Multimodal immunochromatographic sensors (ICSs) have acquired extensive attention since they not only provide reliable results by comparing the different output signals but also flexibly respond to various application environments. Herein, an ICS with triple signal outputs including colorimetry, temperature, and pressure was developed for sensitive detection of chlorothalonil. The multivalent Pt/Ti3C2Tx nanoparticles as signal tags were facilely synthesized by loading PtNPs onto single-layer Ti3C2Tx nanosheets with high surface area. The acquired Pt/Ti3C2TxNPs accelerated the rate-limiting step of the aerogenesis reaction of H2O2 for producing intensive pressure signals due to their significant catalase-mimic activity. Meanwhile, they showed desirable photothermal conversion efficiency in the near-infrared region for producing significant temperature signals. Furthermore, their deep color also allowed facile colorimetry by using the naked eye. Based on a competitive immunoassay, chlorothalonil was detected as a model analyte on this trimodal ICS platform. The detection limits for pressure, temperature, and colorimetric modes were 0.04, 0.09, and 5 ng mL-1, respectively. The recoveries for detecting chlorothalonil supplemented in Astragalus and Honeysuckle with pressure mode were 84.0-110% and 108-114%, respectively. Therefore, the ICS presented a portable, sensitive, accurate, and flexible multimodal strategy suitable for point-of-care testing.

Hierarchical magneto-colorimetric labels for immediate lateral flow immunoassay of chlorothalonil residues.

Quantitative detection of pesticide residues in food and environmental samples using an improved lateral flow immunoassay (LFIA) is of considerable importance for real-time analysis. This paper proposes a highly sensitive LFIA platform based on a hierarchical magneto-colorimetric compact. This compact serves as both the target magnetic enrichment substrate and a photosensitive label. Initially, a large porous dendritic silica template is prepared and doped with superparamagnetic ferric oxide nanoparticles (Fe3O4 NPs) and colloidal gold nanoparticles (AuNPs) at high densities within its vertical channels. The sequential assembly of central-radial channels allow for the three-dimensional integration of these two components, enabling independent control of their discrete functions without mutual interference. Following alkyl organosilicon encapsulation and silica sealing, the composite spheres are then applied in LFIA to detect chlorothalonil residues. Fe3O4 NPs enhance the binding efficiency to target analytes, while AuNPs amplify the signal, leveraging their high loading densities and robust optical properties. The developed LFIA platform exhibited a detection limit of 0.34 ng/mL for chlorothalonil and a linear range of 0.0085-824 ng/mL. The recoveries varied between 85.1 % and 103.1 %, and the relative standard deviations were 1.25%-8.84 %. This LFIA approach demonstrates high sensitivity, specificity, reproducibility and flexible detection modes, making it highly suitable for the on-site monitoring of pesticide residues.

Design, Synthesis, and Bioactivity Determination of Novel Malononitrile Derivatives Containing 1,2,3-Triazole.

Using antifungal agrochemicals as the most economical solution might reduce plant diseases caused by pathogenic fungi, which have a significant negative impact on the quality and yield of food worldwide. In this work, 33 compounds (G) containing 1,2,3-triazole and malononitrile structures were synthesized. When the compounds were tested in vitro against six fungal species, they exhibited significant fungicidal activity toward Botrytis cinerea and Rhizoctonia solani. Compounds G17 and G30 displayed promising in vivo efficacy, with an EC50 of 0.19 and 0.27 mg/L respectively against R. solani. Fungal ergosterol production was suppressed by compounds G17 and G30, according to a preliminary analysis of their mechanism of action on R. solani using transcriptomics and scanning electron microscopy. It has been shown through experimentation that compounds G17 and G30 prevent R. solani from synthesizing ergosterol. Ultimately, it was anticipated that compounds G17 and G30 would be discovered to be low-toxic.

Substrate access tunnel engineering of a Fe-type nitrile hydratase from Pseudomonas fluorescens ZJUT001 for substrate preference adjustment and catalytic performance enhancement.

Substrate access tunnel engineering is a useful strategy for enzyme modification. In this study, we improved the catalytic performance of Fe-type Nitrile hydratase (Fe-type NHase) from Pseudomonas fluorescens ZJUT001 (PfNHase) by mutating residue Q86 at the entrance of the substrate access tunnel. The catalytic activity of the mutant PfNHase-αQ86W towards benzonitrile, 2-cyanopyridine, 3-cyanopyridine, and 4-hydroxybenzonitrile was enhanced by 9.35-, 3.30-, 6.55-, and 2.71-fold, respectively, compared to that of the wild-type PfNHase (PfNHase-WT). In addition, the mutant PfNHase-αQ86W showed a catalytic efficiency (kcat/Km) towards benzonitrile 17.32-fold higher than the PfNHase-WT. Interestingly, the substrate preference of PfNHase-αQ86W shifted from aliphatic nitriles to aromatic nitrile substrates. Our analysis delved into the structural changes that led to this altered substrate preference, highlighting an expanded entrance tunnel region, theenlarged substrate-binding pocket, and the increased hydrophobic interactions between the substrate and enzyme. Molecular dynamic simulations and dynamic cross-correlation Matrix (DCCM) further supported these findings, providing a comprehensive explanation for the enhanced catalytic activity towards aromatic nitrile substrates.

Glassy carbon electrodes modified with graphitic carbon nitride nanosheets and CoNiO2 bimetallic oxide nanoparticles as electrochemical sensor for Sunitinib detection in human fluid matrices and pharmaceutical samples.

A sophisticated electrochemical sensor is presented employing a glassy carbon electrode (GCE) modified with a novel composite of synthesized graphitic carbon nitride (g-C3N4) and CoNiO2 bimetallic oxide nanoparticles (g-C3N4/CoNiO2). The sensor's electrocatalytic capabilities for Sunitinib (SUNI) oxidation were demonstrated exceptional performance with a calculated detection limit (LOD) of 52.0 nM. The successful synthesis and integrity of the composite were confirmed through meticulous characterization using various techniques. FT-IR analysis affirmed the successful synthesis of g-C3N4/CoNiO2 by providing insights into its molecular structure. XRD, FE-SEM, SEM-EDX, and BET analyses collectively validated the material's structural integrity, surface morphology, and electrocatalytic performance. Optimization of key analytical parameters, such as loading volume, concentration, electrolyte solution type, and pH, enhanced the electrocatalytic sensing capabilities of g-C3N4/CoNiO2. The synergistic interaction between g-C3N4 and CoNiO2 bimetallic oxide nanoparticles executed the sensor highly effective in the electrical oxidation of SUNI. Across a concentration range of 0.1-83.8 µM SUNI, the anodic peak current exhibited a linear increase with good precision. Application of the newly developed g-C3N4/CoNiO2 system to detect SUNI in a variety of samples, including urine, human serum, and capsule dosage forms, obtained satisfactory recoveries ranging from 97.1 to 103.0%. This methodology offers a novel approach to underscore the potential of the developed sensor for applications in biological and pharmaceutical monitoring.

Highly efficient synthesis of isoxazolones and pyrazolones using g-C3N4·OH nanocomposite with their in silico molecular docking, pharmacokinetics and simulation studies.

An environmentally friendly, versatile multicomponent reaction for synthesizing isoxazol-5-one and pyrazol-3-one derivatives has been developed, utilizing a freshly prepared g-C3N4·OH nanocomposite as a highly efficient catalyst at room temperature in aqueous environment. This innovative approach yielded all the desired products with exceptionally high yields and concise reaction durations. The catalyst was well characterized by FT-IR, XRD, SEM, EDAX, and TGA/DTA studies. Notably, the catalyst demonstrated outstanding recyclability, maintaining its catalytic efficacy over six consecutive cycles without any loss. The sustainability of this methodology was assessed through various eco-friendly parameters, including E-factor and eco-score, confirming its viability as a green synthetic route in organic chemistry. Additionally, the gram-scale synthesis verifies its potential for industrial applications. The ten synthesized compounds were also analyzed via a PASS online tool to check their several pharmacological activities. The study is complemented by in silico molecular docking, pharmacokinetics, and molecular dynamics simulation studies. These studies discover 5D as a potential candidate for drug development, supported by its favorable drug-like properties, ADMET studies, docking interaction, and stable behavior in the protein binding cavity.

Thermally-Induced Supersaturation Approach for Optimizing Drug Loading and Biopharmaceutical Properties of Supersaturated Lipid-Based Formulations: Case Studies with Ibrutinib and Enzalutamide.

Lipid-based formulations (LbFs) have demonstrated success in pharmaceutical applications; however, challenges persist in dissolving entire doses of the drug into defined liquid volumes. In this study, the temperature-induced supersaturation method was employed in LbF to address drug loading and pill burden issues. Supersaturated LbFs (super-LbF) were prepared using the temperature-induced supersaturation method, where the drug load is above its equilibrium solubility. Further, the influence of the drug's physicochemical and thermal characteristics on drug loading and their relevance with an apparent degree of supersaturation (aDS) was studied using two model drugs, ibrutinib and enzalutamide. All the prepared LbFs were evaluated in terms of physical stability, dispersion, and solubilization capacity, as well as pharmacokinetic assessments. Drug re-crystallization was observed in the lipid solution on long-term storage at higher aDS values of 2-2.5. Furthermore, high-throughput lipolysis studies demonstrated a significant decrease in drug concentration across all LbFs (regardless of drug loading) due to a decline in the formulation solvation capacity and subsequent generation of in-situ supersaturation. Further, the in vivo results demonstrated comparable pharmacokinetic parameters between conventional LbF and super-LbF. The short duration of the thermodynamic metastable state limits the potential absorption benefits. However, super-LbFs of Ibr and Enz showed superior profiles, with 1.7-fold and 5.2-fold increased drug exposure compared to their respective crystalline suspensions. In summary, this study emphasizes the potential of temperature-induced supersaturation in LbF for enhancing drug loading and highlights the intricate interplay between drug properties, formulation characteristics, and in vivo performance.

3D/2D-Bismuth Oxybromide Spheres with Selenium-Doped Graphitic Carbon Nitride Sheets: An Efficient Electrocatalyst for the Detection of Arsenic Drug Roxarsone.

Heavy metals are crucial carcinogenic agents threatening the environment and living habituates. Among them, arsenic (As) is an important metalloid that is categorized as a group I toxic carcinogen. Roxarsone (RX) is an organoarsenic antibiotic compound primarily used as a veterinarian drug and growth promoter for poultry animals. The extensive usage of RX increased the accumulation of As in living beings and the ecosystem. Therefore, we have prepared an electrochemical sensor based on 3D bismuth oxybromide with 2D selenium-doped graphitic carbon nitride (BOB/SCN) electrocatalyst for the rapid detection of RX. The elemental and structural details were thoroughly investigated with several spectroscopic techniques. The electrochemical properties were measured by impedance and voltammetric measurements. The electrocatalytic behavior toward the RX was estimated with different voltammetric methods. Therefore, our BOB/SCN-based electrochemical sensor demonstrated a low detection limit (2.3 nM), low quantification value (7.7 nM), optimal sensitivity (0.675 µA µM-1 cm-2), and good linear ranges (0.01-77 and 77-857 µM). Additionally, this sensor showed good electrochemical performance and was applied to monitor the RX in various real samples with remarkable recoveries. Based on these results, our BOB/SCN sensor is a promising electrochemical platform for determining RX.

Cyanohydrin Equilibria Implicate Non-Aromatic Aldehydes in Photochemical Production of Oceanic Carbon Monoxide.

Carbonyls have previously been dismissed as significant precursors for carbon monoxide (CO) photoproduction from natural chromophoric dissolved organic matter (CDOM). Here, we used hydrogen cyanide (HCN), which reacts with carbonyls to form photochemically inert cyanohydrins, as a probe to re-examine the role of carbonyls in CO photoproduction. Adding HCN to low-absorbance euphotic zone seawater decreased CO photoproduction. Modeling [HCN] (∼5 to 364 µM) vs the percent decrease in CO photoproduction (%CO↓) yielded carbonyl-cyanohydrin dissociation equilibrium constants, KD, and maximum %CO↓, %CO↓max values. Four Atlantic and Pacific seawater KDs (66.7 ± 19.6 µM) overlap aqueous aliphatic but not aromatic aldehyde KDs. Phenylacetaldehyde (PA) and other ß,γ-unsaturated aldehydes are proposed as prototypical CO precursors. Direct photolysis of ∼10 nM PA can supply the measured daily production of HCN-sensitive CO at an open-ocean site near Bermuda. HCN's %CO↓max was 31 ± 2.5% in North Atlantic seawater vs the 13 ± 2.5% inhibition of CO photoproduction by borohydride, a dilemma since only borohydride affects most ketones. Borohydride also decreased CDOM absorption much more than did HCN. This puzzle probably reflects differing steric and solvation requirements in HCN- and borohydride-CDOM reactions. This study demonstrates cyanophilic aldehydes to be a significant source of open-ocean CO and reveals new clues regarding CDOM photochemistry mechanisms.

Functionalized cyanostilbene-based nano-AIEgens: multipoint binding interactions for improved sensing of gallic acid in real-life food samples.

Cyano-substituted stilbene (CSS) derivatives have been synthesized that can form luminescent nanoscopic assemblies in an aqueous medium. The optical properties of such materials, as governed by the relative ratios of their monomer and aggregated forms, are found to be susceptible to pH and temperature of the medium. The compound with boronic acid attached at the terminal positions shows a turn-on fluorescence response (LOD: 15.4 ppb) with gallic acid (GA). The mechanistic studies indicate that the 1,2-diol unit of GA is involved in ester formation with the boronic acid residue, while the carboxylic end engages in hydrogen bonding interaction with the nitrile unit. Such multi-point binding interaction provides better selectivity over other structurally similar analytes. Moreover, the distinct aggregation properties of such boronate ester derivatives are responsible for the GA-specific optical response. The sensory system has been utilized for the determination of the levels of GA derivatives in tea (green tea and black tea) and various fruit (mango, orange, guava, pomegranate) extracts. In all cases, the estimated values of GAE were found to be in the same range reported by others. Finally, low-cost, chemically-modified paper strips have been designed for rapid, on-location detection of GA.

Bimetal loaded graphitic carbon nitride with synergistic enhanced peroxidase-like activity for colorimetric detection of p-phenylenediamine.

In recent years, great progress has been made on the study of nanozymes with enzyme-like properties. Here, bimetallic Fe and Ni nanoclusters were anchored on the nanosheets of nitrogen-rich layered graphitic carbon nitride by one-step pyrolysis at high temperature (Fe/Ni-CN). The loading content of Fe and Ni on Fe/Ni-CN is as high as 8.0%, and Fe/Ni-CN has a high specific surface area of 121.86 m2 g-1. The Fe/Ni-CN can effectively oxidize 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H2O2, and exhibits efficient peroxidase-like activity, leading to a 17.2-fold increase compared to pure graphitic carbon nitride (CN). Similar to the natural horseradish peroxidase (HRP), the Fe/Ni-CN nanozyme follows catalytic kinetics. The Michaelis-Menten constant (Km) value of the Fe/Ni-CN nanozyme for TMB is about 8.3-fold lower than that for HRP, which means that the Fe/Ni-CN nanozyme has better affinity for TMB. In addition, the catalytic mechanism was investigated by combination of free radical quenching experiments and density-functional theory (DFT) calculations. The results show that the high peroxidase-like activity is due to the easy adsorption of H2O2 after bimetal loading, which is conducive to the production of hydroxyl radicals. Based on the extraordinary peroxidase-like activity, the colorimetric detection of p-phenylenediamine (PPD) was constructed with a wide linear range of 0.2-30 µM and a low detection limit of 0.02 µM. The sensor system has been successfully applied to the detection of residual PPD in real dyed hair samples. The results show that the colorimetric method is sensitive, highly selective and accurate. This study provides a new idea for the efficient enhancement of nanozyme activity and effective detection of PPD by a bimetallic synergistic strategy.

Biocatalytic Synthesis of Ruxolitinib Intermediate via Engineered Imine Reductase.

An enzyme catalyzed strategy for the synthesis of a chiral hydrazine from 3-cyclopentyl-3-oxopropanenitrile 5 and hydrazine hydrate 2 is presented. An imine reductase (IRED) from Streptosporangium roseum was identified to catalyze the reaction between 3-cyclopentyl-3-oxopropanenitrile 5 and hydrazine hydrate 2 to produce trace amounts of (R)-3-cyclopentyl-3-hydrazineylpropanenitrile 4. We employed a 2-fold approach to optimize the catalytic performance of this enzyme. First, a transition state analogue (TSA) model was constructed to illuminate the enzyme-substrate interactions. Subsequently, the Enzyme_design and Funclib methods were utilized to predict mutants for experimental evaluation. Through three rounds of site-directed mutagenesis, site saturation mutagenesis, and combinatorial mutagenesis, we obtained mutant M6 with a yield of 98% and an enantiomeric excess (ee) of 99%. This study presents an effective method for constructing a hydrazine derivative via IRED-catalyzed reductive amination of ketone and hydrazine. Furthermore, it provides a general approach for constructing suitable enzymes, starting from nonreactive enzymes and gradually enhancing their catalytic activity through active site modifications.