High Activity Research Articles

Pathological and neurochemical correlates of locus coeruleus functional network activity

The locus coeruleus (LC) produces the neuromodulators norepinephrine and dopamine, and projects widely to subcortical and cortical brain regions. The LC has been a focus of neuroimaging biomarker development for the early detection of Alzheimer’s disease (AD) since it was identified as one of the earliest brain regions to develop tau pathology. Our recent research established the use of positron emission tomography (PET) to measure LC catecholamine synthesis capacity in cognitively unimpaired older adults. We extend this work by investigating the possible influence of pathology and LC neurochemical function on LC network activity using functional magnetic resonance imaging (fMRI). In separate sessions, participants underwent PET imaging to measure LC catecholamine synthesis capacity ([18F]Fluoro-m-tyrosine), tau pathology ([18F]Flortaucipir), and amyloid-β pathology ([11C]Pittsburgh compound B), and fMRI imaging to measure LC functional network activity at rest. Consistent with a growing body of research in aging and preclinical AD, we find that higher functional network activity is associated with higher tau burden in individuals at risk of developing AD (amyloid-β positive). Critically, relationships between higher LC network activity and higher pathology (amyloid-β and tau) were moderated by LC catecholamine synthesis capacity. High levels of LC catecholamine synthesis capacity reduced relationships between higher network activity and pathology. Broadly, these findings support the view that individual differences in functional network activity are shaped by interactions between pathology and neuromodulator function, and point to catecholamine systems as potential therapeutic targets.

Genotype-Specific Activation of Autophagy during Heat Wave in Wheat

Recycling of unnecessary or dysfunctional cellular structures through autophagy plays a critical role in cellular homeostasis and environmental resilience. Therefore, the autophagy trait may have been unintentionally selected in wheat breeding programs for higher yields in arid climates. This hypothesis was tested by measuring the response of three common autophagy markers, ATG7, ATG8, and NBR1, to a heat wave under reduced soil moisture content in 16 genetically diverse spring wheat landraces originating from different geographical locations. We observed in the greenhouse trials that ATG8 and NBR1 exhibited genotype-specific responses to a 1 h, 40 °C heat wave, while ATG7 did not show a consistent response. Three genotypes from Uruguay, Mozambique, and Afghanistan showed a pattern consistent with higher autophagic activity: decreased or stable abundance of both ATG8 and NBR1 proteins, coupled with increased transcription of ATG8 and NBR1. In contrast, three genotypes from Pakistan, Ethiopia, and Egypt exhibited elevated ATG8 protein levels alongside reduced or unaltered ATG8 transcript levels, indicating a potential suppression or no change in autophagic activity. Principal component analysis demonstrated a correlation between lower abundance of ATG8 and NBR1 proteins and higher yield in the field trials. We found that (i) the combination of heat and drought activated autophagy only in several genotypes, suggesting that despite being a resilience mechanism, autophagy is a heat-sensitive process; (ii) higher autophagic activity correlates positively with greater yield; (iii) the lack of autophagic activity in some high-yielding genotypes suggests contribution of alternative stress-resilient mechanisms; and (iv) enhanced autophagic activity in response to heat and drought was independently selected by wheat breeding programs in different geographic locations.

Effect of the gonadotropin surge on steroid receptor regulation in preovulatory follicles and newly formed corpora lutea in the cow

The objective of the study was to characterize the mRNA expression patterns of specific steroid hormone receptors namely, estrogen receptors (ESRRA—estrogen related receptor alpha and ESRRB—estrogen related receptor beta) and progesterone receptors (PGR) in superovulation-induced bovine follicles during the periovulation and subsequent corpus luteum (CL) formation. The bovine ovaries (n = 5 cow / group), containing preovulatory follicles or early CL, were collected relative to injection of the gonadotropin-releasing hormone (GnRH) at (I) 0 h, (II) 4 h, (III) 10 h, (IV) 20 h, (V) 25 h (preovulatory follicles) and (VI) 60 h (CL, 2–3 days after induced ovulation). In this experiment, we analyzed the steroid receptor mRNA expression and their localization in the follicle and CL tissue. The high mRNA expression of ESRRA, ESRRB, and PGR analyzed in the follicles before ovulation is significantly reduced in the group of follicles during ovulation (25 h after GnRH), rising again significantly after ovulation in newly formed CL, only for ESRRA and PGR (P < 0.05). Immunohistochemically, the nuclei of antral follicles' granulosa cells showed a positive staining for ESRRA, followed by higher activity in the large luteal cells just after ovulation (early CL). In contrast, the lower PGR immunopresence in preovulatory follicles increased in both small and large luteal cell nuclei after follicle ovulation. Our results of steroid receptor mRNA expression in this experimentally induced gonadotropin surge provide insight into the molecular mechanisms of the effects of steroid hormones on follicular–luteal tissue in the period close to the ovulation and subsequent CL formation in the cow.

A natural glutathione S-transferase gene GSTU23 confers metabolic resistance to metamifop in Echinochloa crus-galli

Herbicides are essential for farmers to control weed. However, prolonged use of herbicides has caused facilitated the development of herbicide resistance in weeds. Here, the resistant-E. crus-galli (RL5) was obtained by continuous treatment with metamifop for five generations in paddy fields. RL5 plants showed a 13.7-fold higher resistance to metamifop compared to SL5 plants. Pre-treatment with GST inhibitor (NBD-Cl) significantly increased the susceptibility of RL5 plants to metamifop. Faster metamifop metabolism and higher GST activity in RL5 plants than in SL5 plants were also confirmed, highlighting the role of GST in metabolic resistance. RNA-Seq analysis identified EcGSTU23 as a candidate gene, with up-regulated expression observed in RL5 and field-resistant E. crus-galli plants. Furthermore, the EcGSTU23 gene was overexpressed in the transgenic EcGSTU23-Maize, and the EcGSTU23-Maize showed resistance to metamifop. In vitro metabolic studies also revealed that the purified EcGSTU23 displayed increased catalytic activity in glutathione (GSH) conjugation, and metamifop was metabolized more rapidly in the co-incubation system containing EcGSTU23 protein. These results provide direct experimental evidence of EcGSTU23's involvement in the metabolic resistance of E. crus-galli to metamifop. Understanding the resistance mechanism can help in devising effective strategies to combat herbicide resistance and breeding of genetically modified herbicide resistant crops.

Alkaline electrochemical oxygen reduction boosted by trimetallic palladium–copper–gold nanoparticles

A Pd-Cu-Au/C nanocatalyst with a low content of Cu (8.2 at %) and Au (4.4 at %), and an average crystallite size of about 2 nm was synthesized by employing a one-pot two-steps borohydride reduction method in the presence of sodium citrate, characterized by energy-dispersive X-ray spectroscopy, X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy and examined for the oxygen reduction reaction (ORR) in an alkaline solution. Pd/C and Pd-Cu/C catalyst with 17 at % Cu, which were synthesized by the same method, and a commercial Pt/C were used for comparison. In addition, Pd-Cu-Au/C and Pd-Cu/C nanocatalysts were treated in acid with a purpose of their dealloying. The electrochemically active surface area of Pd was determined from COads desorption. It was found that the ORR on all catalysts follows first order kinetics with respect to O2 with four electrons transferred per O2 molecule. The catalysts were subjected to a short-term cycling stability test. Pd-Cu/C and Pd-Cu-Au/C were more active for ORR than Pd/C and Pt/C. The acid-treated catalysts exhibited higher activity compared to their untreated counterparts; both initially and after the stability test (up to 1.7 times in specific activity and 2 times in mass activity). The catalyst with the highest specific and mass activity after the stability test was the acid-treated Pd-Cu-Au/C which surpassed Pd/C by a factor of up to 2.5 in specific activity and 5.7 in mass activity. It was concluded that the acid treatment leads to a major dissolution of Cu from the nanoparticles, thus leaving a highly disordered Pd structure exhibiting increased activity for the ORR, while Au stabilizes Pd structure contributing to better performance after the stability test.

One-Pot Synthesis of C@BiOBr for Efficient Photocatalytic Degradation of Phenol.

This work describes the synthesis of C@BiOBr using glucose as the carbon precursor by a repeatable one-step hydrothermal method. Characterization studies indicate that the structure of BiOBr did not change after the carbon layer was encapsulated on the surface. The highest activity is achieved at 1.2-C@BiOBr, with 97% of phenol (50 mg·L-1) degrading within 90 min, and the degradation amount of phenol is determined to be 48.5 mg·g-1 with a speed of 0.54 mg·g-1·min-1. The useful species of phenol degradation are studied and assigned to •O2-, 1O2, and h+. The effect of coated carbon layer for photocatalytic degradation of phenol over BiOBr is studied by photoelectrochemical experiments, fluorescence spectra, and density functional theory (DFT) calculations. It is attributed to the good conductivity of carbon, enhanced separation of the photocarriers by carbon coating, and thermodynamically favorable reactive oxygen species (ROS) production on the surface of carbon. This work demonstrates that carbon coating is an effective strategy to improve the photocatalytic activity of BiOBr and reveals the detailed mechanism.

Nanometric-Mapping and In Situ Quantification of Site-specific Photoredox Activities on 2D Nanoplates.

Defective layered bismuth oxychloride (BiOCl) exhibits excellent photocatalytic activities in water purification and environmental remediation. Herein, in situ single-molecule fluorescence microscopy is used to spatially resolve the photocatalytic heterogeneity and quantify the photoredox activities on individual structural features of BiOCl. The BiOCl nanoplates with respective dominant {001} and {010} facets (BOC-001 and BOC-010) are fabricated through tuning the pH of the solution. The corner position of BOC-001 exhibits the highest photo-oxidation turnover rate of 262.7 ± 30.8s-1µm-2, which is 2.1 and 65.7 times of those of edges and basal planes, respectively. A similar trend is also observed on BOC-010, which can be explained by the heterogeneous distribution of defects at each structure. Besides, BOC-001 shows a higher photoredox activity than BOC-010 at corners and edges. This can be attributed to the superior charge separation ability, active high-index facets of BOC-001, and its co-exposure of anisotropic facets steering the charge flow. Therefore, this work provides an effective strategy to understand the facet-dependent properties of single-crystalline materials at nanometer resolution. The quantification of site-specific photoredox activities on BiOCl nanoplates sheds more light on the design and optimization of 2D materials at the single-molecule level.

Effect of diets containing probiotic yeast Cystobasidium benthicum and fruit Cyrtocarpa edulis on growth and immune parameters of Nile tilapia (Oreochromis niloticus)

This study investigates Cystobasidium benthicum (Cb) probiotic yeast and Cyrtocarpa edulis (Ce) fruit dietary effects, single (0.5%) or combined (Cb:Ce, 0.25:0.25%), on growth performance, humoral immunity in serum and skin mucus, and intestinal morphology of Nile tilapia (Oreochromis niloticus) after 14 and 28 days. The Cb group presented the highest (P < 0.05) specific growth rate, weight gain, and absolute growth rate with respect to the control group. Immunological assays indicated that Cb, Ce and Cb:Ce groups increased serum nitric oxide concentration compared to the control group (P < 0.05). Cb and Cb:Ce groups showed the highest serum myeloperoxidase enzyme activity at day 14 and 28, respectively (P < 0.05); whereas, Cb:Ce group had the highest (P < 0.05) myeloperoxidase activity in skin mucus. The superoxide dismutase enzyme activity was unaffected. On day 28, Cb, Ce, and Cb:Ce groups showed higher and lower (P <0.05) catalase enzyme activity in serum and skin mucus, respectively, compared with the control group. Only the Cb group had higher (P <0.05) total protein concentration in serum (day 14) and skin mucus (day 14 and 28) with respect to the control group. The lysozyme activity in serum (day 28) and skin mucus (day 14) was higher (P <0.05) in the Cb group compared to the control group. Only the skin mucus of Ce group showed bactericidal activity against Aeromonas dhakensis (P <0.05). Histological studies indicated that Cb and Cb:Ce groups increased microvilli height, and Cb, Ce and Cb:Ce augmented goblet cell area at day 14 compared to the control group (P <0.05). At day 28, microvilli height was higher in all groups and the number of intraepithelial leukocytes increased in Cb and Ce groups with respect to the control group (P <0.05). The ex vivo assay revealed that A. dhakensis in leukocytes decreased cell viability similar to the control group (P <0.05). A principal component analysis (PCA) confirmed the results. In conclusion, C. benthicum in the diet was the best supplement to improve the growth and immunity of Nile tilapia.

The impact of nimodipine combined with Ginkgo biloba extract on cognitive function and ADL scores in patients with Parkinson's disease: A retrospective study.

This study aims to explore the value of nimodipine combined with Ginkgo biloba extract in improving cognitive function and daily living abilities in patients with Parkinson's disease. Clinical data from 551 patients with Parkinson's disease admitted to the Neurology Department of the Affiliated Hospital of Beihua University from January 2022 to December 2022 were retrospectively collected. Cognitive function and daily living abilities were assessed in patients before treatment, and a reevaluation was conducted after 12 weeks of medication. Patients treated solely with nimodipine were categorized into the monotherapy group, while patients treated with nimodipine combined with Ginkgo biloba extract were included in the combination group. After 1:1 propensity score matching, a total of 83 pairs of patients were matched, and differences in relevant indicators between the 2 groups were compared. The total effective rate of treatment in the combination group was 90.36%, which was higher than the control group at 72.29% (P < .05). However, after treatment, the observation group showed higher Mini-Mental State Examination and activities of daily living scores compared to the control group (P < .05). The combined treatment of nimodipine and Ginkgo biloba extract in patients with Parkinson's disease has a significant effect and can effectively improve cognitive function and enhance daily living abilities.

Effect of Support Functionalization on Catalytic Direct Hydrogenation and Catalytic Transfer Hydrogenation of Muconic Acid to Adipic Acid

The liquid-phase hydrogenation of muconic acid (MA) to produce bio-adipic acid (AdA) is a prominent environmentally friendly chemical process, that can be achieved through two distinct methodologies: catalytic direct hydrogenation using molecular hydrogen (H2), or catalytic transfer hydrogenation utilizing a hydrogen donor. In this study, both approaches were explored, with formic acid (FA) selected as the hydrogen source for the latter method. Palladium-based catalysts were chosen for these processes. Metal’s nanoparticles (NPs) were supported on high-temperature heat-treated carbon nanofibers (HHT-CNFs) due to their known ability to enhance the stability of this metal catalyst. To assess the impact of support functionalization on catalyst stability, the HHT-CNFs were further functionalized with phosphorus and oxygen to obtain HHT-P and HHT-O, respectively. In the hydrogenation reaction, catalysts supported on functionalized supports exhibited higher catalytic activity and stability compared to Pd/HHT, reaching an AdA yield of about 80% in less than 2 h in batch reactor. The hydrogen-transfer process also yielded promising results, particularly with the 1%Pd/HHT-P catalyst. This work highlights the efficacy of support functionalization in improving catalyst performance, particularly when formic acid is used as a safer and more cost-effective hydrogen donor in the hydrogen-transfer process.

Aliphatic Ketone Claisen Rearrangement: Troubleshooting the Transetherification Step by Identifying a Stable Acid Catalyst.

After optimization for retention of catalytic activity, 4-chlorobenzoic acid emerged as the optimal catalyst for the aliphatic ketone Claisen rearrangement. The optimal catalyst enables a one-pot, metal-free, catalytic protocol from allylic alcohols to γ,δ-unsaturated ketones. The optimized process tolerates a range of substrates, including substituents with acid-labile protecting groups. Reaction monitoring and DFT studies of the aliphatic ketone Claisen process agree that the ultimate rearrangement step typically has the highest activation barrier.

The antioxidant and antimicrobial activity of ethanolic extract in roots, stems, and leaves of three commercial Cymbopogon species

BackgroundCymbopogon is a member of the family Poaceae and has been explored for its phytochemicals and bioactivities. Although the antimicrobial activities of Cymbopogon spp. extracts have been extensively studied, comprehensive analyses are required to identify promising compounds for the treatment of antimicrobial resistance. Therefore, this study investigated the antioxidant and antimicrobial properties of Cymbopogon spp. ethanolic extracts in every single organ.MethodsEthanolic extracts were obtained from three Indonesian commercial species of Cymbopogon spp., namely Cymbopogon citratus (L.) Rendle, Cymbopogon nardus (DC.) Spatf., and Cymbopogon winterianus Jowitt. The leaf, stem, and root extracts were evaluated via metabolite profiling using gas chromatography-mass spectrometry (GC–MS). In silico and in vitro analyses were used to evaluate the antioxidant and antimicrobial properties of the Cymbopogon spp. ethanolic extracts. In addition, bioactivity was measured using cytotoxicity assays. Antioxidant assays were performed using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2-azino-bis [3-ethylbenzothiazoline-6-sulfonic acid (ABTS) to determine toxicity to Huh7it-1 cells using a tetrazolium bromide (MTT) assay. Finally, the antimicrobial activity of these extracts was evaluated against Candida albicans, Bacillus subtilis, Staphylococcus aureus, and Escherichia coli using a well diffusion assay.ResultsGC–MS analysis revealed 53 metabolites. Of these, 2,5-bis(1,1-dimethylethyl)- phenol (27.87%), alpha-cadinol (26.76%), and 1,2-dimethoxy-4-(1-propenyl)-benzene (20.56%) were the predominant compounds. C. winterianus and C. nardus leaves exhibited the highest antioxidant activity against DPPH and ABTS, respectively. Contrastingly, the MTT assay showed low cytotoxicity. C. nardus leaf extract exhibited the highest antimicrobial activity against E. coli and S. aureus, whereas C. winterianus stem extract showed the highest activity against B. substilis. Furthermore, computational pathway analysis predicted that antimicrobial activity mechanisms were related to antioxidant activity.ConclusionsThese findings demonstrate that the leaves had strong antioxidant activity, whereas both the leaves and stems showed great antimicrobial activity. Furthermore, all Cymbopogon spp. ethanolic extracts showed low toxicity. These findings provide a foundation for future studies that assess the clinical safety of Cymbopogon spp. as novel drug candidates.

Aloe vera Miller extract as a plasticizer agent to polymeric films: A structural and functional component

The pharmaceutical and cosmetic industries have found natural polysaccharides-based polymeric films helpful for the topical application of drugs. Plasticizers, such as glycerol, are added to achieve films' desired mechanical, elastic, and flexible properties. Aloe vera Miller mucilage is known for healing burns and wounds, relieving pain, and moisturizing, suggesting its great potential for managing multiple topical issues. Herein, we exploited the plasticizing potentialities of A. vera extract when combined with gellan or carrageenan polysaccharides to produce films. The extract of A. vera mucilage was prepared in propane-1,2-diol, and its composition was comparatively evaluated with a commercial extract using a chemometric method. Next, it was added to the films obtained using the solvent-casting method. The formulations were investigated regarding the mechanical properties, swelling, water loss, porosity, water vapor transmission rate, degree of occlusion, adhesion force, and antioxidant action. Fourier transform infrared spectroscopy assessed the films stability and homogeneity with an exploratory chemometric method to classify the samples. The results showed that carrageenan and gellan polysaccharides-based polymeric films have great potential for including A. vera extract. The extract acts as a plasticizer and promotes desirable properties and swelling behavior for films intending wound management. Comparatively, films prepared with glycerol beyond the extract presented higher thickness, lower swelling, and higher occlusion and antioxidant activity. Despite this, glycerol seems to negatively influence the homogeneity of the extract on the film surface. In addition, regarding polysaccharides, carrageenan showed higher bioadhesion. Therefore, the films produced exhibited favorable properties, highlighting their potential for further research regarding wound management.

Fabrication of poly (1,4-phenylene ether ether sulfone) modified with MWCNTs/reduced (GO-oxSWCNTs) NCs for enhanced antimicrobial activities

Poly (1,4-phenylene ether ether sulfone) (PEES) is a commonly used polymer in membrane technology for water treatment applications such as water purification and blood dialyzing in hemodialysis. In this study, PEES was chemically modified by nitration, yielding nitrated Poly (1,4-phenylene ether ether sulfone) (NPEES). Following that, NPEES nanocomposites (NCs) comprise multi-walled carbon nanotubes (MWCNTs), and the process involved the synthesis of reduced graphene oxide-oxidized single-walled carbon nanotubes, abbreviated as reduced (GO-oxSWCNTs). Various characterization techniques were used on the created membranes, such as Fourier-transform infrared spectroscopy (AT-FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis. All polymer nanocomposites were found to be amorphous, according to the XRD patterns. SEM scans revealed random crater-like features on the surface of NPEES, but MWCNTs and reduced (GO-oxSWCNTs) NCs were distributed evenly on the polymer surface. The primary goal of this study was to evaluate the antimicrobial activity of modified NPEES membranes against two Gram-positive bacteria, Staphylococcus aureus (S. aureus) and Bacillus subtilis (B. subtilis), two Gram-negative bacteria, Pseudomonas aeruginosa (P. aeruginosa) and Escherichia coli (E. coli), and a fungus, Candida albicans (C. albicans). All modified membranes, including NPEES, NPEES/MWCNTs NCs, and NPEES/MWCNTs/reduced (GO-oxSWCNTs) NCs, exhibited antibacterial activity against S. aureus and B. subtilis. Notably, when compared to NPEES/MWCNTs NCs and NPEES/MWCNTs/reduced (GO-oxSWCNTs) NCs, the NPEES membrane had higher antibacterial activity, generating a 12 mm inhibitory zone. Furthermore, molecular docking studies revealed a strong fit of the tested polymer nanocomposites into the DNA gyrase B active site (PDB ID: 4uro), which was consistent with the practical results of their antibacterial activity evaluation.

Preparation of transparent and flexible regenerated kenaf CNF composite films with curcumin-metal complex for food packaging applications

Cellulose nanofibers (CNF) derived from kenaf plant were combined with curcumin (Cur)-metal complexes to produce regenerated composite films. Cur was used to synthesize homoleptic Cur-metal complexes with diamagnetic Zn(II) and paramagnetic Cu(II) metal ions. Cur-Zn(II) complex and Cur-Cu(II) complex were synthesized under the same reaction conditions to check the synergistic effect of engaging the diketone electrons of Cur with strong coordination bonds with two different metal ions. The synthesized Cur-metal complexes were used as fillers to produce CNF composite films for biodegradable food packaging film. Results showed that the Cur-Zn(II) complex-loaded CNF composite films exhibit higher antioxidant activity than other films whereas Cur-Cu(II) complex-loaded CNF composite films showed prominent antibacterial activity against foodborne pathogenic bacteria such as Listera monocytogenes and Escherichia coli. It is due to the coordination of the diketone electron of Cur with diamagnetic and paramagnetic metal ions that influenced the antioxidant and antibacterial properties of Cur. Overall, this study proved that it was possible to use Cur in the form of Cur-Zn(II) complex as an antioxidant filler and Cur-Cu(II) complex as an antibacterial filler for active food packaging applications.

What Effects Do Magnetic Fields Exert on the Bioaccumulation of Galanthamine and Lycorine, Growth Efficiency, Capacity to Scavenge Free Radicals, and Defense Enzyme Activities of Summer Snowflakes (Leucojum aestivum L.)?

Leucojum aestivum L. is a bulbous Amaryllidaceae family plant. A pot experiment was conducted to investigate the impact of three different magnetic field (MF) intensities [50, 100 and 150 militesla (mT)] with three different exposure durations (1, 3 and 7 days) on growth parameters, alkaloid levels (galanthamine and lycorine), non-enzymatic antioxidant activities (total phenol-flavonoid content and free radical scavenging activity), and enzymatic antioxidant activities [superoxide dismutase (SOD) and catalase (CAT)] compared with control (no MF) in the bulbs and leaves. Maximum bulb length was achieved with 150 mT MF application for 3 days. Galanthamine levels increased by 63% in the bulbs with 150 mT-7 days exposure and by 79.8% in the leaves with 50 MT-1 day exposure compared to the control. The leaves and bulbs with 100 mT exposure showed the greatest increases in lycorine concentrations (23.8% and 62.3% rises, respectively). MF exposures of 150 mT for 3 days gave the best radical scavenging activity and total phenol-flavonoid content. The highest alkaloid levels in the bulbs were associated with higher SOD and CAT activity generated by MF treatments. This study revealed that the medicinal value and quantity of L. aestivum bulbs could be significantly increased with 150 mT MF intensity.

Monitoring Enzymatic Reaction Kinetics and Activity Assays in Confined Nanospace.

Enzyme-mediating biotransformations commonly occur in micro- and nanospace, which is crucial to maintain the essential biochemical processes and physiological functions in living systems. Probing enzyme-catalytic reactions in a biomimetic fashion remains challenging due to the lack of competent tools and methodology. Here, we show that studying enzymatic reaction kinetics can be readily achieved by a well-designed solid-state nanopore. Using tyrosine as a classical substrate, we quantitatively characterize the catalytic activity of tyrosinase (TYR) and tyrosine decarboxylase (TDC) in a nanoconfined space. Tyrosine was first immobilized in the nanopipette, wherein the active sites of tyrosine were left unoccupied. When successively exposed to TYR and TDC, a two-step cascade reaction can spontaneously take place. In this process, the surface wettability and charge of the nanopipette stemming from the catalytic products can sensitively regulate ion transport and ionic current rectification behavior, which were monitored by ionic current signal. In this biomimetic scenario, we obtained the enzymatic reaction kinetics of monophenyl oxidase that were not previously actualized in the conventional macroenvironment. Significantly, TYR showed higher enzyme activity, with a Km value of 1.59 mM, which was lower than that measured in a free and open space (with a Km of 3.01 mM). This suggests that tyrosine should be the most appropriate substrate of TYR, thus improving our understanding of tyrosine-associated biochemical reactions. This work offers an applicable technical platform to mimic enzyme-mediated biotransformations and biometabolisms.

Unveiling the potential of NiO–ZnCo2O4 nano-composites: Electrical, optical, electrochemical and antibacterial investigation

Zinc Cobaltite (ZCO) and Nickel Oxide (NiO) nanoparticles (NPs) were synthesized using a sol-gel technique, and their composites with different weight ratios were prepared using a straightforward sonication method. The NiO and ZCO NPs had small crystallite size of 10 nm and 18 nm, respectively. According to the ultraviolet–visible (UV–Vis) spectra, pure NiO and ZCO NPs exhibited band gaps of ∼3.5 eV and 3.3 eV. Antibacterial activity against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacterial strains was also tested for the composite counterpart and its equivalents. Compared to pure NPs, the composite of 30 % ZCO-NiO (NZ3) had higher antibacterial activity with zone of inhibition of ∼13 mm against E. coli. The electrical and electrochemical properties were also explored and it was found that the composite of 50 % ZCO-NiO (NZ5) shows high specific capacitance of 188 F/g.

M/BiOCl-(M=Pt, Pd, and Au) Boosted Selective Photocatalytic CO2 Reduction to C2 Hydrocarbons via *CHO Intermediate Manipulation.

Selective CO2 photoreduction to C2 hydrocarbons is significant but limited by the inadequate adsorption strength of the reaction intermediates and low efficiency of proton transfer. Herein, an ameliorative *CO adsorption and H2O activation strategy is realized via decorating bismuth oxychloride (BiOCl) nanostructures with different metal (Pt, Pd, and Au) species. Experimental and theoretical calculation results reveal that distinct *CO binding energies and *H acquisition abilities of the metal cocatalysts mediate the CO2 reduction activity and hydrocarbon selectivity. The relatively moderate *CO adsorption and *H supply over Pd/BiOCl endows it with the lowest free energy to generate *CHO, leading to its highest activity of hydrocarbon production. Specifically, the Pt cocatalyst can efficiently participate in H2O dissociation to deliver more *H for facilitating the protonation of the *CHO and *CHOH, thereby favoring CH4 production with 76.51% selectivity. A lower *H supply over Pd/BiOCl and Au/BiOCl results in a large energy barrier for *CHO or *CHOH protonation and thus a more thermodynamically favored OC─CHO coupling pathway, which endows them with vastly increased C2 hydrocarbon selectivity of 81.21% and 92.81%, respectively. The understanding of efficient C2 hydrocarbon production in this study sheds light on how materials can be engineered for photocatalytic CO2 reduction.

Enhanced solar-driven photocatalytic hydrogen production, dye degradation, and supercapacitor functionality using MoS2–TiO2 nanocomposite

In our current study, we've devised a promising method to overcome the limitations of nanostructured titanium dioxide (TiO2) with molybdenum disulfide (MoS2) nanoflowers synthesized through a cost-effective and straightforward solvothermal process. The resulting heterostructures function as highly efficient photocatalysts and supercapacitors. The synthesized MoS2–TiO2 nanocomposite demonstrated exceptional performance in various applications, including efficient hydrogen (H2) evolution, dye degradation, and enhanced supercapacitor performance. The combination of MoS2, a two-dimensional transition metal dichalcogenide, and TiO2, a wide-bandgap metal oxide semiconductor, addresses critical challenges in clean energy, environmental remediation, and energy storage. Photocatalytic studies revealed that the MoS2–TiO2 catalysts exhibited the highest activity for hydrogen production, with a rate of 137.93 μmol h−1 g−1, which is three times greater than that of pure MoS2. Additionally, the MoS2–TiO2 nanocomposite demonstrated superior electrochemical performance, with a specific capacitance of 638 F/g. Electrochemical impedance spectroscopy (EIS) showed that the charge transfer kinetics were comparable, highlighting the positive impact of TiO2 without significantly increasing resistance. The MoS2–TiO2 nanocomposite emerges as a transformative material with multifaceted applications, showcasing its versatility in addressing global challenges related to clean energy and environmental sustainability.