High Specific Activity Research Articles

High Specific Activity during Electrochemical CO2 Reduction through Homogeneous Deposition of Gold Nanoparticles on Gas Diffusion Electrodes

High Specific Activity during Electrochemical CO₂ Reduction through Homogeneous Deposition of Gold Nanoparticles on Gas Diffusion Electrodes

Co-encapsulation of Creatininase, Creatinase, and Sarcosine Oxidase in Yeast Spore for Creatinine Degradation.

Creatinine clearance is used to reflect the glomerular filtration rate to assess kidney function. Creatinine degradation-related enzymes have been used for creatinine detection in clinical medicine. The mixture of spores encapsulating either creatininase or creatinase or sarcosine oxidase could mediate a three-step reaction to produce hydrogen peroxide from creatinine. In this study, to achieve consecutive and efficient creatinine detection, degradation enzymes creatininase, creatinase, and sarcosine oxidase were co-encapsulated in a single Saccharomyces cerevisiae spore. The co-encapsulation spores performed high specific activity and enzymatic properties and converted creatinine to H2O2, which was 160% higher than the mixture of spores that individually expressed these three enzymes. The detection condition of co-encapsulation was optimized for the store at room temperature and resistance to environmental stresses. The S. cerevisiae spores can co-encapsulate enzyme families and catalyze consecutive reactions in the spore wall, having potential application prospects.

Cloning, expression, and purification of recombinant AKR1D1 for therapeutic applications.

AKR1D1, a key enzyme in the aldo-keto reductase superfamily, plays a dual role in both steroid metabolism and bile acid synthesis by catalyzing the NADPH-dependent reduction of carbon-carbon double bonds, specifically converting 3-ketosteroid hormones into 5β-steroids. Positioned at the critical intersection of steroid hormone and bile acid metabolism, AKR1D1 has the potential to profoundly influence metabolic homeostasis and drug metabolism. Despite its importance, the enzyme's therapeutic implications and role in drug metabolism remain underexplored. This study presents an optimized methodology for the cloning, expression, and purification of AKR1D1 using an Escherichia coli expression system. We identified optimal conditions for ligation and precise DNA sequencing, emphasizing the need for lower DNA concentrations and higher purity. Protein expression was evaluated in E. coli strains BL21 and Rosetta, with the highest yields achieved under extended incubation at 25 °C with controlled IPTG concentrations. Using freshly transformed cells was essential for maintaining consistent protein expression. The enzyme's activity was confirmed using a spectrofluorometric assay, demonstrating efficient reduction of testosterone to 5β-DHT. This optimized methodology facilitates the production of AKR1D1 with high specific activity, establishing a valuable platform for future research. It enables a deeper investigation into AKR1D1's contributions to drug metabolism and its therapeutic potential.

Growth Rates and Specific Aminoacyl-tRNA Synthetases Activities in Clupea harengus Larvae

Gaining robust in situ estimates of the growth rate of marine fish larvae is essential for understanding processes controlling year-class success and developing sustainable management strategies to maintain good environmental status. We measured the growth rate of Atlantic herring (Clupea harengus) larvae in the laboratory and compared it to the activity of aminoacyl-tRNA synthetases (AARS). Larvae were reared under controlled conditions for 20 days at three temperatures (7, 12, and 17 °C) using different prey concentrations (0.1, 0.3, and 2 prey·mL−1) of the copepod Acartia tonsa. The relationship between specific growth rates (SGR) and specific AARS activities was best described by a linear function—SGR = −0.1031 + 0.0017 · spAARS, r2 = 0.71, p < 0.05—when only larvae fed ad libitum were considered regardless of the temperature. When larvae fed with low concentrations of food were included in the analysis, the relationship was SGR = −0.0332 + 0.0010 · spAARS, r2 = 0.42, p < 0.05. This latter slope was rather low compared to other studies performed in zooplankton. We suggest protein degradation during the early life stages of fish as the cause of this low slope. We also studied SGR under food deprivation and the effect on specific AARS activities. We found rather high specific AARS activities in small individuals of early stages of fish, also suggesting protein degradation. Further research about protein degradation and turnover rates is needed in order to use AARS activity as a proxy for growth rates in field-caught larvae.

Heterologous expression and enzymological characterization of L-glutamate oxidase from the marine actinomycete Streptomyces lydicamycinicus NBRC 110027.

We successfully constructed a heterologous expression system for L-glutamate oxidase from the marine actinomycete Streptomyces lydicamycinicus NBRC 110027 (Sl-LGOX) in Escherichia coli BL21(DE3) as a host. This is the first example of L-glutamate oxidase from a marine microorganism. A chemically synthesized gene optimized for codon usage in E. coli was used as the inserted fragment, which was effective for enzyme expression. We expressed Sl-LGOX in the soluble fraction of E. coli BL21(DE3)/pET21b-Sl-lgox. We also succeeded in purifying recombinant Sl-LGOX (rSl-LGOX) to homogeneity from the cell-free extract of this clone via an Ni-NTA column. rSl-LGOX showed high specificity for L-Glu and was active and stable over a wide range of temperatures and pH values. In particular, it showed high specific activity and stability at an acidic pH. A variety of applications can take advantage of the unique enzymatic properties of rSl-LGOX.

Substrate expansion of Geotrichum candidum alcohol dehydrogenase towards diaryl ketones by mutation

Chiral diaryl alcohols, such as (4-chlorophenyl)(pyridin-2-yl)methanol, are important intermediates for pharmaceutical synthesis. However, using alcohol dehydrogenases (ADHs) in the asymmetric reduction of diaryl ketones to produce the corresponding alcohols is challenging due to steric hindrance in the substrate binding pockets of the enzymes. In this study, the steric hindrance of the ADH from Geotrichum candidum NBRC 4597 (G. candidum acetophenone reductase, GcAPRD) was eliminated by simultaneous site-directed mutagenesis of Phe56 (in the large pocket) and Trp288 (in the small pocket). As a result, two double mutants, Phe56Ile/Trp288Ala, and Phe56Ala/Trp288Ala, exhibited much higher specific activities towards 2-(4′-chlorobenzoyl)pyridine (4.5 μmol/min/mg and 3.4 μmol/min/mg, respectively) than the wild type (< 0.2 μmol/min/mg). In whole-cell-catalyzed asymmetric reductions of diaryl ketones, Phe56Ile/Trp288Ala significantly increased the isolated yields, which were over 90% for the reactions of most of the tested substrates. Regarding enantioselectivity, Phe56Ile/Trp288Ala and Phe56Ala/Trp288Ala, and Trp288Ala generally exhibited similar selectivity to produce (R)-alcohols with up to 97% ee.Key points• Phe56 in Geotrichum reductase (GcAPRD) was mutated to eliminate steric hindrance.• Mutation at Phe56 increased enzymatic activity and expanded substrate specificity.• Phe56Ile/Trp288Ala showed high activity and (R)-selectivity towards diaryl ketones.Graphical

Structural and Compositional Tuning of Platinum Alloy Nanowires for Enhanced Oxygen Reduction Reaction

Polymer electrolyte fuel cells (PEFCs) have gained considerable attention due to their high energy density, high conversion efficiency, and wide operating temperatures. The main challenges encountered in the commercialization of PEFCs are the sluggish kinetics and low durability of the cathodic oxygen reduction reaction (ORR) catalyst. The conventional electrocatalyst, platinum (Pt) nanoparticles (2~5nm) dispersed on carbon support, suffer insufficient catalytic activity and low durability owing to enlargement in particle size due to particle coalescence or Ostwald ripening during PEFC operations. In this scenario, the facile fabrication of advanced functional catalysts with improving ORR activity and stability is significant for PEFCs.Among the various catalysts reported so far in the literature, Pt is an effective metal for catalyzing the ORR reaction due to its intrinsic catalytic performance and stability, however, it's scarcity and high cost limit its large-scale practical application. Compared to nanoparticle counterparts, the anisotropic one-dimensional nanostructure has been explored for higher activity due to its high flexibility, outstanding conductivity, and thermal stability.1–3 Several strategies have been adopted in the literature to enhance the catalytic activity and the Pt utilization efficiency. One aspect is the atomic scale tuning of the Pt chemical environment through proper alloying with bimetallic or trimetallic elements. In addition, it is essential to construct favorable structures in alloy systems with maximum exposed active sites.In this work, we synthesized a unique nanostructure of Pt alloy nanowires (PtNiCo NW) through a solvothermal method by reducing the Pt, Ni, and Co precursors in a solvent mixture with reducing agents and surfactants (oleyl amine with W(CO)6, glucose and CTAB). The atomic scale tailoring of the Pt chemical environment of the catalyst was achieved by varying the alloy composition. The TEM observation indicates that structural changes occurred by changing the reaction conditions of the catalysts; initially, smooth nanowires are formed with a diameter of 2 nm (Fig. 1a) followed by the formation of the rough surface due to an increase in the reduction of Ni over the Pt NWs over time. A porous nanostructure of Pt with Ni (Fig 1b) was fabricated through an acid treatment process.The electrochemical surface area and ORR activities of the PtNiCo NWs on carbon support were estimated from rotating disk electrode measurements in 0.1 M HClO4 electrolyte solution. Compared with the smooth PtNiCo NW catalyst, the porous PtNiCo NW catalyst with a rough surface exhibited a higher mass activity of 1.6 ± 0.1 Amg-Pt−1 and an excellent specific activity of 3.7 ± 0.2 mAcm-Pt−2. The higher specific activity would arise from the increased roughness on the Pt surface through the formation of porous structure and the optimized surface-active sites on the catalyst surface through composition tuning.AcknowledgmentThis presentation is based on the results obtained from the project, JPNP20003, commissioned by the New Energy and Industrial Technology Development Organization (NEDO), Japan.References M. Li et al, Science, 2016, 354 (6318), 1414–1419.X. Tian et al, Science, 2019, 336 (6467), 850–856.K. Jiang et al, Sci. Adv., 2017, 3(2), e160170. Fig 1. TEM images of Pt-based nanowires having (a) smooth and (b) rough-porous structures. Figure 1

Preparation and Characterization of Platinum-Cobalt Nanosheets for Oxygen Reduction Reaction

Enhancing the efficiency of Pt-based electrocatalysts for the oxygen reduction reaction (ORR) is crucial for the broader use of polymer electrolyte fuel cells. Pt-based electrocatalysts are commonly used at the cathode side of polymer electrolyte fuel cells to facilitate the ORR, which is the most sluggish process during cell operation. Pt nanosheet prepared via topotactic reduction of platinum oxide nanosheets showed large electrochemically active surface area (ECSA)and high mass specific activity (MA).1 The addition of cobalt into the Pt nanosheet is expected to enhance and improve overall electrocatalytic performance as PtCo alloy nanoparticles are known to have higher specific activity than pure Pt. In this study, we present the synthesis and characterization of cobalt-doped platinum-oxide nanosheets ((Pt,Co)Ox NS) and their transformation into carbon-supported Pt-Co nanosheets for potential electrochemical applications.The (Pt,Co)Ox NS colloid was obtained through exfoliation in aqueous solution by modification of our previous synthesis process.1 The results demonstrated enhanced electrocatalytic activity of the (Pt,Co)Ox NS composite compared to pure platinum-oxide nanosheets. For the pure platinum-oxide nanosheets, the ECSA was 97 m2 (g-Pt)-1. Moreover, employing the Koutecky-Levich equation, the MA was determined to be 321 A g-1 at 0.9 V vs. RHE, and the specific activity was 332 µA cm-2. For the PtCo nanosheets, the ECSA was similar at 91 m2 (g-Pt)-1. However, owing to the Co electronic effect, the specific activity rose to 576 µA cm-2, leading to an overall increase in MA to 524 A g-1 at 0.9 V vs. RHE. This improvement is attributed to the synergistic effect between cobalt and platinum, which enhances the oxygen reduction process. Reference: D. Takimoto, S. Toma, Y. Suda, T. Shirokura, Y. Tokura, K. Fukuda, M. Matsumoto, H. Imai, and W. Sugimoto, Nat Commun 14, 19 (2023)

Next Generation Cathode Catalyst Layer Design with High Oxygen Permeable Ionomer – Benefits, Challenges, and Prospects for Heavy Duty Fuel Cell Applications

Proton Exchange Membrane Fuel Cell (PEMFC) has a growing demand to power zero emission fuel cell applications. Ballard is the fuel cell industry leader, developing the next generation core technology to fulfill such demand and giving continuous efforts on cost reduction. Key requirements in fuel cell market applications include high power density and long-life operation, while maintaining high efficiencies and reducing costs. This places a high demand on improving catalyst performance and electrode layer transport, which can be sustained over the duration of the product lifetime. To reduce fuel cell membrane electrode assembly (MEA) cost, the push for high performance catalyst layers (CLs) with low platinum (Pt) loadings results in new challenges for the cathode material selection and electrode design. The increased oxygen transport resistance that occurs at lower catalyst loadings with reduced available catalyst electrochemical active surface area (ECSA), causes two very closely related challenges: 1) greater performance losses at high current density increases the difficulty to achieve the power requirements for the heavy duty market, and 2) the loss of catalyst ECSA via platinum dissolution over time puts additional demands on the design to achieve the end of life (EOL) performance requirement. Therefore, a combination of material solution, design choice and processing parameters are the key to optimize next generation cathode design for fuel cell applications1.One material solution to achieve high performance while reducing catalyst loadings is the development of high oxygen permeable ionomer (HOPI) that mitigates oxygen transport limitations at the Pt surface. Chemours has developed a HOPI with a bulky, sterically rigid monomer group in the ionomer backbone, which disrupts the packing density, improving oxygen permeability on the catalyst surface2. One of the key challenges of HOPI integration and the scale-able fabrication of the catalyst layer is high crack density of CL due to the rigid nature of the ionomer. Ballard has integrated HOPI in the cathode CL overcoming scale-able fabrication challenges through appropriate process parameter selection and evaluated CL performance. The use of accelerated testing and modeling approach developed by numerous product iteration, has been applied for lifetime estimation for HOPI technology introduction. In this talk, we will discuss details about benefit of High Oxygen Permeable Ionomer (HOPI) in next generation cathode CL design.Recently, key requirements in heavy-duty market applications are placing more importance on high efficiency rather than high power density to reduce fuel cost rather catalyst cost. Reaching the target lifetime, catalyst overloading to 0.45 mg/cm2 total Pt in anode and cathode, and 44% active membrane area oversizing are suggested3. Therefore, to achieve high efficiency target, high catalyst activity is more desired. Interestingly, HOPI also showed high specific activity due to the mitigation of catalyst poisoning by sulfonate anion groups4. We will also discuss the catalyst layer design prospect with HOPI for such transition on heavy duty market application.Acknowledgement: US Department of Energy (DOE) funded heavy duty MEA development project (DE-EE0008822).References M. Dutta, A. Young, V. Colbow, J. Bellerive and S. Knights 2020 Examining Catalyst Layer Design Strategies for Improved Fuel Cell Performance and Durability. ECS PRiME 2020S. Litster et al. 2020 Durable High-Power Density Fuel Cell Cathodes for Heavy-Duty Vehicle. DOE AMR 2020K. Ahluwalia and X. Wang 2024 Performance and Durability of Hybrid Fuel Cell Systems for Class-8 Long Haul Trucks. J. Electrochem. Soc. 171 034507R. Jinnouchi, K. Kudo and K. Kodama 2021 The role of oxygen-permeable ionomer for polymer electrolyte fuel cells. Nat Commun 12, 4956.

Changes in Protease Activity of Ginger Rhizome during Postharvest Storage

It has been reported that ripe ginger rhizomes contain proteolytic enzymes. In this study, we investigated the fluctuations in protease activity from ginger rhizomes stored after harvest for the utilization of proteases. The juice from ginger rhizomes that had been stored for 4 months after harvest exhibited the highest specific protease activity. Additionally, juices with high specific protease activity could form soymilk and cow milk gels. Electrophoresis experiments revealed that the protein bands in ginger rhizome juice were degraded by the proteases contained in the juice. This degradation was prevented by adding the cysteine protease inhibitor E-64.

Anatase‐reinforced PtZn@Silicalite‐1 structured catalysts boosting propane dehydrogenation

AbstractStructured catalysts exhibit the advantages of high diffusion efficiency and low heat transfer resistance, which have attracted increasing attention to non‐adiabatic gas–solid process. However, the metal‐supported coating catalysts face the problems of weaker bond strength and severe sintering, especially under the conditions of large flow rate and high temperature. Herein, metal@Silicalite‐1 structured catalysts with high adhesion and thermal stability were successfully prepared by hydroxylating the substrate with anatase. Rich surface Ti‐OH significantly strengthened the adhesion stability of the zeolite coating. In propane dehydrogenation reaction, the optimized PtZn@S‐1‐15Ti showed a high specific activity of 49.6 molC3H6·molPt−1·s−1 with propylene selectivity above 99% at 600°C. The introduction of anatase accelerated the aggregation of silicon sources and induced nucleation with growth content of zeolite increased by 3.6 times. It breaks the inherent contradiction between high loading amount and strong binding ability of coated catalysts, which broadens the avenues for industrial applications.

Immuno-PET Imaging of CD93 Expression with 64Cu-Radiolabeled NOTA-mCD93 ([64Cu]Cu-NOTA-mCD93) and Insulin-Like Growth Factor Binding Protein 7 ([64Cu]Cu-NOTA-IGFBP7).

CD93 is overexpressed in multiple solid tumor types, serving as a novel target for antiangiogenic therapy. The goal of this study was to develop a 64Cu-based positron emission tomography (PET) tracer for noninvasive imaging of CD93 expression. Antimouse-CD93 mAb (mCD93) and the CD93 ligand IGFBP7 were conjugated to a bifunctional chelator, p-isothiocyanatobenzyl-1,4,7-triazacyclononane-1,4,7-triacetic acid (p-SCN-NOTA) and labeled with 64Cu. To evaluate the pharmacokinetic properties and tumor-targeting efficacy of [64Cu]Cu-NOTA-mCD93 and [64Cu]Cu-NOTA-IGFBP7, PET imaging and biodistribution were performed on both 4T1 murine breast tumor-bearing mice and MDA-MB-231 human breast tumor-bearing mice. The tumor model HT1080-FAP, which does not overexpress CD93, was used as a negative control. Fluorescent immunostaining was conducted on different tissues to correlate radiotracer uptake with CD93 expression. 64Cu-labeling was achieved with high yield and specific activity. Serial PET imaging revealed that the in vivo performance of [64Cu]Cu-NOTA-IGFBP7 was superior to that of [64Cu]Cu-NOTA-mCD93, and that the tracer [64Cu]Cu-NOTA-IGFBP7 exhibited elevated tumor uptake values and excellent tumor retention in MDA-MB-231 mice, rather than in 4T1 murine mice. The MDA-MB-231 tumor uptake of [64Cu]Cu-NOTA-IGFBP7 was 2.85 ± 0.15, 3.69 ± 0.60, 6.91 ± 0.88, and 6.35 ± 0.55%ID/g at 1, 4, 24, and 48 h p.i., respectively, which were significantly higher than that in the CD93-negative HT1080-FAP tumor (0.73 ± 0.15, 0.97 ± 0.31, 1.00 ± 0.07, and 1.02 ± 0.11%ID/g, respectively). The significant difference between positive and negative tumors indicated [64Cu]Cu-NOTA-IGFBP7 was specifically binding to CD93. Biodistribution data as measured by gamma counting were consistent with the PET analysis. Ex vivo histology further confirmed the high CD93 expression on MDA-MB-231 tumor tissues. Herein, we prepared two novel radiotracers, [64Cu]Cu-NOTA-mCD93 and [64Cu]Cu-NOTA-IGFBP7, for the first immune-PET imaging of CD93 expression. Our results suggest that [64Cu]Cu-NOTA-IGFBP7 is a more potential radiotracer for visualizing angiogenesis due to its sensitive, persistent, and CD93-specific characteristics.

Homogenous Palladium-Catalyzed Dehalogenative Deuteration and Tritiation of Aryl Halides with D2/T2 Gas.

Hydrogen isotopically labeled compounds have extensive utility across diverse domains, especially in drug discovery and development. However, synthesis of the labeled compounds with exclusive site selectivity and/or high isotope incorporation is challenging. One widely employed method is heterogeneous palladium(0)-catalyzed (such as Pd/C) dehalogenative deuteration and tritiation with D2/T2 gas. While commonly used, the method faces two long-standing challenges related to insufficient isotope incorporation and functional group tolerance, particularly with aryl bromides and chlorides. These long-standing issues pose a substantial obstacle in the synthesis of deuterated drug molecules and high-specific-activity tritium tracers. Herein, we present a novel palladium catalytic system using Zn(OAc)2 as an additive, enabling novel homogenous dehalogenative deuteration/tritiation using D2/T2 gas. Under mild reaction conditions, a wide range of drug-like aryl halides and pseudohalides undergo selective deuteration with complete isotope incorporation. The reaction displays excellent compatibility with diverse functional groups, including multiple bonds and O/N-benzyl, and cyano groups, which are frequently problematic in the Pd/C reactions. Furthermore, this method was successfully applied to the tritiation of four halogenated pharmaceutically relevant molecules, resulting in predictable high specific activity per halogen atom (26.5-27.7 Ci/mmol). Notably, the developed system allows gram-scale preparation of a deuterium-containing intermediate, a crucial step in synthesizing a deuterium-labeled drug molecule. A key intermediate, Pd(Ar)OAc, is proposed to activate hydrogen gas during dehalogenative deuteration and tritiation, and Zn(OAc)2 plays an essential role in inhibiting Pd poisoning by halides.

Carbon-anchoring synthesis of Pt1Ni1@Pt/C core-shell catalysts for stable oxygen reduction reaction

Proton-exchange-membrane fuel cells demand highly efficient catalysts for the oxygen reduction reaction, and core-shell structures are known for maximizing precious metal utilization. Here, we reported a controllable “carbon defect anchoring” strategy to prepare Pt1Ni1@Pt/C core-shell nanoparticles with an average size of ~2.6 nm on an in-situ transformed defective carbon support. The strong Pt–C interaction effectively inhibits nanoparticle migration or aggregation, even after undergoing stability tests over 70,000 potential cycles, resulting in only 1.6% degradation. The stable Pt1Ni1@Pt/C catalysts have high oxygen reduction reaction mass activity and specific activity that reach 1.424 ± 0.019 A/mgPt and 1.554 ± 0.027 mA/cmPt2 at 0.9 V, respectively, attributed to the optimal compressive strain. The experimental results are generally consistent with the theoretical predictions made by our comprehensive microkinetic model which incorporates essential kinetics and thermodynamics of oxygen reduction reaction. The consistent results obtained in our study provide compelling evidence for the high accuracy and reliability of our model. This work highlights the synergy between theory-guided catalyst design and appropriate synthetic methodologies to translate the theory into practice, offering valuable insights for future catalyst development.

Transglutaminase from Asian seabass liver: purification, characterization and cross-linking activity against natural actomyosin

The study investigated the purification and characterization of transglutaminase (TGase) from Asian seabass liver. In addition, protein cross-linking ability of partially purified TGase was also elucidated against the natural actomyosin extracted from threadfin bream surimi. During ammonium sulfate fractionation, the highest specific activity (11.31 ± 0.17 units/mg protein) was obtained from the 80–100% ammonium sulfate (AS) fraction (partially purified TGase; pTGase). Purity increased 1.46 times compared to crude samples with a 73% yield. Further purification using DEAE-Sepharose enhanced the specific activity (904.71 ± 4.65units/mg protein) by 117.19-fold as compared to the crude sample. The molecular weight (MW) of the purified TGase was 43.4 kDa, which was slightly different than the MW determined by SDS-PAGE (41.1 kDa). Optimal TGase activity was found at 45–50 °C and pH 8, with significant declines beyond these ranges. Furthermore, TGase maintained activity (80%) when heated till 55 °C, whereas it showed wide-range pH stability. NaCl and CaCl2 at 3% and 20 mM, respectively enhanced TGase activity. When natural actomyosin (NAM) was treated with pTGase at various concentrations (1–10 unit/mg protein), decreasing solubility and ɛ-amino groups confirmed its cross-linking ability. The result was also supported by the formation of aggregates of NAM proteins as determined by transmission electron microscopic images. Thus, Asian seabass liver could be a new source of purified and partially purified TGase, which can be employed for various food and pharmaceutical applications.

Enhanced Peroxidase-like Activity of Ruthenium-Modified Single-Atom-Thick A Layers in MAX Phases for Biomedical Applications.

Nanozymes have demonstrated significant potential as promising alternatives to natural enzymes in biomedical applications. However, their lower catalytic activity compared to that of natural enzymes has limited their practical utility. Addressing this challenge necessitates the development of innovative enzymatic systems capable of achieving specific activity levels of natural enzymes. In this study, we focus on enhancing the catalytic performance of nanozymes by introducing Ru atoms into the single-atom-thick A layer of the V2SnC MAX phase, resulting in the formation of V2(Sn0.8Ru0.2)C with Ru single-atom sites. The V2(Sn0.8Ru0.2)C MAX phase demonstrated an exceptional peroxidase-like specific activity of up to 1792.6 U mg-1, surpassing the specific activity of a previously reported horseradish peroxidase (HRP). Through X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) investigations, it has been revealed that both the V2C atom layers and single-atom-thick Sn readily accept a negative charge from Ru, leading to a reduction of the energy barrier for H2O2 adsorption. This discovery has enabled the successful application of V2(Sn0.8Ru0.2)C in the development of a lateral flow immunoassay for heart failure biomarkers, achieving a detection sensitivity of 4 pg mL-1. Additionally, V2(Sn0.8Ru0.2)C demonstrated exceptional broad-spectrum antibacterial efficacy. This study lays the groundwork for the precise design of MAX phase-based nanozymes with high specific activity, offering a viable alternative to natural enzymes for various applications.

Радиоэкологические исследования в районе архипелага Земля Франца-Иосифа в августе и сентябре 2023 года

The results of a study of the current activity of technogenic isotopes in the coastal zone of the Alexandra Land island of the Franz Josef Land archipelago are presented. Samples of sea water, algae, bottom sediments, soil and vegetation were taken during an expedition carried out under the auspices of the Northern Fleet and the Russian Geographical Society in August and September 2023. In the marine environment and littoral macrophytes, the content of technogenic 137Cs is gradually decreasing in comparison with the indicators of the previous period 2000–2010. In the terrestrial ecosystem, the distribution 137Cs is mosaic; the highest specific activity is found in soils (up to 71.4 Bq/kg). In single samples, the presence of the short-lived isotope 134Cs was noted, which is an indicator of relatively recent atmospheric fallout in the Arctic.

Lily bulb polyphenol oxidase obtained via an optimized multi-stage separation strategy for structural analysis and browning mechanism elucidation

An optimized multi-stage separation strategy was developed to purify lily bulb polyphenol oxidase (PPO) for revealing its molecular structure. The PPO was purified 14.64-fold with high specific activity of 153,900 U/mg via optimized conditions of phosphate buffer pH (6.5), solid-liquid ratio (1:3), PVPP content (2 %), extraction time (4 h), followed by 30 %–50 % ammonium sulfate, diethylaminoethyl ion-exchange chromatography (0.1 M NaCl), and size exclusion chromatography. The PPO was identified as a dimeric protein with molecular weight of 135 kDa, containing 58.79 % random coil, 20.78 % α-helix, 17.41 % β-folding, and 3.02 % β-corner. The three-dimensional structure via homology modeling suggested that active center CuA bound to His151, His172, and His181, CuB bound to His307, His311, and His341. Furthermore, molecular docking indicated that its Phe337 and Tyr312 residues were catalytic cavity gates of catechol and 4-methylcatechol, respectively. Therefore, this study successfully analyzed purified PPO structure and further provided a theoretical foundation for its browning mechanism.

High activity of cobalt-atomically dispersed catalyst on mesoporous carbon for rechargeable Zn-air batteries via effective removal of the hard template

The use of oxygen from air in Zn-air batteries requires the smart design of materials with bifunctional activity for oxygen reduction and evolution reactions (ORR/OER), and with a porous structure to facilitate the diffusion of oxygen gas to active sites. Kit-6 template-assisted porous structures have been proposed to this end; however, traditional methods for the removal of Kit-6 templates are highly aggressive and environmentally harmful. In this study, we present the synthesis of a cobalt atomically dispersed catalyst (Co-ADC) with interlayer engineering using mesoporous Kit−6 templates, focusing on two removal strategies: sodium hydroxide (0.5, 1, and 2 M) and hydrofluoric acid (15, 30, and 45 %). Physicochemical results indicated that Co-ADC-containing nanoparticles were obtained using the proposed methodology, while the use of HF promoted the loss of cobalt in the catalyst. During the activity evaluation for the ORR, and it was found that 0.5 M NaOH and HF at 15 % displayed similar activity, which could be related to the effect of carbon material as co-catalyst, but the first enabled a close 4e− pathway, and thus, the Co-ADC presented a ΔEOER-ORR of 640 mV. This optimized ADC displayed improved functionality owing to diffusion improvements by the mesoporous structure, presenting a maximum power density of 130.6 mW cm−2 and 30 % higher specific activity than the Pt + IrO2/C reference material. Rechargeability was evaluated, yielding a ΔV = 0.87 V at 5.175 mA cm−2 with a round-trip efficiency of 57.5 %. Nonetheless, the optimized material presented higher rechargeability, displaying no significant round-trip changes after 100 cycles, while Pt + IrO2/C presented changes due to OER issues after only 48 cycles.

PSMA and Sigma-1 receptor dual-targeted peptide mediates superior radionuclide imaging and therapy of prostate cancer

Radionuclide therapy, in particular peptide receptor radionuclide therapy (PRRT), has emerged as a valuable means to combat malignant tumors. The specific affinity of ACUPA peptide toward prostate-specific membrane antigen (PSMA) renders the successful development of PRRT for prostate cancer. The clinical outcome of PRRT is, however, generally challenged by moderate tumor uptake and off-target toxicity. Here, we report on a novel design of Sigma-1 receptor and PSMA dual-receptor targeted peptide (S1R/PSMA-P) for superior radionuclide imaging and therapy of prostate cancer. S1R/PSMA-P was acquired with good purity and could efficiently be labeled with 177Lu to yield 177Lu-S1R/PSMA-P with high specific activity and radiostability. Interestingly, 177Lu-S1R/PSMA-P revealed greatly enhanced affinity to LNCaP cells over single-targeted control 177Lu-PSMA-617. The single photon emission computed tomography (SPECT) imaging demonstrated exceptional uptake and retention of 177Lu-S1R/PSMA-P in LNCaP tumor, affording about 2-fold better tumor accumulation while largely reduced uptake by most normal tissues compared to 177Lu-PSMA-617. The selective uptake in LNCaP tumor was also visualized by positron emission tomography (PET) with 68Ga-S1R/PSMA-P. In accordance, a single and low dosage of 177Lu-S1R/PSMA-P at 11.1 MBq effectively suppressed tumor growth without causing apparent side effects. This dual-targeting strategy presents an appealing radionuclide therapy for malignant tumors.