Higher Peroxidase Activity Research Articles

Function Analysis of Heme Peroxidase Genes, MpPxd2 and MpPxd4, Under Thiacloprid Exposure in the Neonicotinoid-Resistant Myzus persicae (Sulzer)

The green peach aphid, Myzus persicae, is a notorious pest worldwide. We collected a field population of the pest (FZQ-F) that exhibited high resistance to neonicotinoids. Exposure to neonicotinoids can induce oxidative damage in animals; however, it remains unclear whether antioxidant enzymes contribute to the innate immune response of neonicotinoid-resistant pests against high doses of insecticides. Treatment with sublethal doses of thiacloprid (LC10 and LC25) for 3, 6, 12, 24, 48, and 72 h resulted in significantly increased reactive oxygen species (ROS), including H2O2 content, in FZQ-F adults, indicating insecticide-induced oxidative stress. Additionally, the peroxidase activity in FZQ-F adults increased after thiacloprid exposure. Using comparative genomics, we identified 31 heme peroxidases in M. persicae with a typical “2Cys” structure, and phylogenetic analyses divided them into five groups. Comparative transcriptomes revealed that MpPxd2 and MpPxd4 were significantly upregulated in thiacloprid-treated aphids. Thiacloprid exposure significantly induced MpPxd2 and MpPxd4 expression levels, consistent with high H2O2 content and peroxidase activity. The knockdown of MpPxd2 or MpPxd4 in FZQ-F increased their susceptibility to imidacloprid, thiacloprid, and thiamethoxam, verifying the protective role of the heme peroxidases against neonicotinoids in aphids. The knockdown of MpPxd2 or MpPxd4 also led to shorter longevity and a low fecundity of adult aphids at 31 °C compared to controls. The results show that MpPxd2 or MpPxd4 is important in how cells respond to oxidative stress and may help resistant M. persicae pests to handle neonicotinoids.

A Fe/Zn Dual Single-Atom Nanozyme with High Peroxidase Activities for Detection of Penicillin G.

Penicillin G (PG) is a common antibiotic, and its accumulation in the environment can pose a threat to the ecological system and ultimately impact human health. Nanozymes have emerged as highly stable enzyme mimics that can be utilized as sensors to achieve the sensitive detection of specific antibiotics. Herein, we report on a dual single-atom Fe/Zn nanozyme (DSAzyme) synthesized from Fe-imidazole as the guest and zeolite imidazole framework-8 as the host. The DSAzyme exhibits intriguing properties that mimic the activities of two natural enzymes: peroxidase and lactamase. Both activities are utilized for the design of a colorimetric sensor for the specific detection of PG: the peroxidase activity enables color generation from 3,3',5,5'-tetramethylbenzidine and H2O2, and the lactamase activity provides the recognition of PG. The nanozyme consists of many Fe-N4 and Zn-N4 site and mechanistic characterizations by experimental investigations and theoretical calculations identify Fe-N4 as the main active center for the peroxidase activity and Zn-N4 as the main binding site for PG. The sensor can achieve a limit of detection of 47 nM, is able to detect PG from real-life samples, remains fully functional after 8-month storage, and retain high activities after reuse for fives times. Taken together, our study provides a new approach to the detection of antibiotics in environmental samples.

Smartphone-based colorimetric paper chip sensor using single-atom nanozyme for the detection of carbofuran pesticide residues in vegetables

Carbofuran (CBF), which exhibit high toxicity, persistent residues, ease of accumulation, and resistance to degradation, pose serious threats to human health and harm the ecological environment. Therefore, there is an urgent need to develop a rapid and accurate method for detecting CBF. In this work, a low-cost, portable, and easy-to-use paper chip biosensor was developed, integrating smartphones for the detection of CBF pesticide residues. This biosensor facilitates rapid on-site testing, meeting the needs for immediate analysis. CBF has the ability to inhibit acetylcholinesterase (AChE) activity. In the presence of AChE, acetylthiocholine (ATCh) is hydrolyzed to produce thiocholine (TCh). TCh, in turn, can inhibit the catalytic activity of Ni-N-C single-atom nanozymes (SAzyme) synthesized using Ni(OH)2 nanochip as a metal precursor, which possess high peroxidase activity. Consequently, the concentration of CBF can be determined by observing the resultant color changes. The results showed that this sensor had a good linear response in the range of CBF concentration from 10 to 500 ng/mL, and the LOD was as low as 8.79 ng/mL. In testing three actual samples—Chinese cabbage, cabbage, and lettuce—the recoveries ranged from 81.09% to 125.27%. This demonstrated that the proposed smartphone-based colorimetric paper chip sensor, utilizing Ni-N-C SAzyme, offers an immediate, convenient, and rapid new strategy for detecting CBF.

Robust and sensitive colorimetric detection of glutathione with double-triggering MOF-Fe(DTNB)

Glutathione (GSH) levels have been well validated to correlate with a variety of physiological and pathological conditions, such as malignancy, cardiovascular disease and aging, making the development of accurate, robust and sensitive GSH detection methods highly desirable. In this study, a novel metal–organic framework (MOF-Fe(DTNB))-based colorimetric method with a favorable dual-triggering function was proposed. MOF-Fe(DTNB) exhibits high peroxidase activity, which can catalyze the oxidation of colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to blue ox-TMB by hydrogen peroxide (H2O2). This oxidation process of TMB can be inhibited not only by the reducing action of GSH, but also by the thiol exchange reaction between DTNB and GSH, in which the disulfide bond of DTNB in MOF-Fe(DTNB) is cleaved. Thus, with this dual triggering mechanism, the GSH concentration can be robustly measured in the MOF-Fe(DTNB)-derived colorimetric strategy. Significantly, this method is accurate (RSD < 6 %), selective and sensitive in biological plasma samples, with satisfactory recovery rates (96.7–103.3 %). It requires less instrumentation and has less interference from other substances. The linear range of the method is 0–80 µM, and the detection limit is as low as 0.28 µM. This dual-triggering MOF-Fe(DTNB)-derived colorimetric strategy has greatly simplified the GSH detection processes with improved accuracy, in both acidic and basic environments, which has potent applications in biochemical analysis and point-of-care testing.

Parental environment as a factor shaping salinity tolerance in halophyte Tripolium pannonicum L.

Parental environment can significantly influence a range of plant traits across different growth phases and developmental stages. The impact of parental salinity variability on offspring germination and environmental factor response still requires thorough investigation. Therefore, we investigated seeds of Tripolium pannonicum L. from low-saline (Cie) and high-saline (Ino) habitats to elucidate the germination potential and adaptation potential of progeny to varying salinity levels. Germination and growth experiments were conducted to analyze germination parameters, plant areas, water-related traits, the concentration of organic solutes, malondialdehyde, and the activity of crucial oxidative defence enzymes. In the germination experiment, Cie seeds demonstrated higher germination potential with longer germination time under 200–400 mM NaCl compare with Ino seeds. The Cie population achieved the highest shoot and roots area at 100 mM and 300 mM NaCl, respectively. The Ino population exhibited its highest shoot and roots area at 200 mM NaCl. The Ino population indicated an increase in stem cortex cell area at 400 mM NaCl. The Ino population enhanced the synthesis of osmolytes as part of the salinity tolerance mechanism. Antioxidant enzyme analysis indicated higher peroxidase activity in Ino and higher superoxide dismutase activity in Cie under salinity, suggesting distinct enzymatic roles in salinity adaptation between populations. Our findings highlight the critical role of parental environmental conditions in shaping progeny traits, enhancing germination potential, and enabling adaptation of progeny plants to diverse environmental niches. The study underscores population-specific responses to environmental factor, emphasizing the complexity of halophyte adaptation mechanisms to salinity.

Mesoporous cerium oxide nanoenzyme for Efficacious impeding tumor and metastasis via Conferring resistance to anoikis

Tumor cells can survive when detached from the extracellular matrix or lose cell-to-cell connections, leading to a phenomenon known as anoikis resistance (AR). AR is closely associated with the metastasis and proliferation of tumor cells, enabling them to disseminate, migrate, and invade after detachment. Here, we have investigated a novel composite nanoenzyme comprising mesoporous silica/nano-cerium oxide (MSN-Ce@SP/PEG). This nanoenzyme exhibited satisfactory catalase (CAT) activity, efficiently converting high levels of H2O2 within tumor cells into O2, effectively alleviating tumor hypoxia. Furthermore, MSN-Ce@SP/PEG nanoenzyme demonstrated high peroxidase (POD) activity, elevating reactive oxygen species (ROS) levels and attenuating AR in hepatocellular carcinoma (HCC) cells. The MSN-Ce@SP/PEG nanoenzyme exhibited satisfactory dual bioactivity in CAT and POD and was significantly enhanced under favorable photothermal conditions. Through the synergistic effects of these capabilities, the nanoenzyme disrupted the epithelial-mesenchymal transition (EMT) process in detached HCC cells, ultimately inhibiting the recurrence and metastasis potential of anoikis-resistant HCC cells. This study represents the first report of a novel nanoenzyme based on mesoporous silica/nano-cerium oxide for treating AR in HCC cells, thereby suppressing HCC recurrence and metastasis. The findings of this work offer a pioneering perspective for the development of innovative strategies to prevent the recurrence and metastasis of HCC.

A thermo-sensitive hydrogel with prominent hemostatic effect prevents tumor recurrence via anti-anoikis-resistance

Tumor cells can survive when detached from the extracellular matrix (ECM) or lose cell–cell connections, a phenomenon known as anoikis-resistance (AR). AR is closely associated with tumor cell metastasis and recurrence, enabling tumor cells to disseminate, migrate, and invade after detachment. To address this issue, a novel intervention method combining intraoperative hemostasis with multifunctional nanozyme driven-enhanced chemodynamic therapy (ECDT) has been proposed, which holds the potential to weaken the AR capability of tumor cells and suppress tumor recurrence. Here, a nanocomposite containing a dendritic mesoporous nanoframework with Cu2+ was developed using an anion-assisted approach after surface PEG grafting and glucose oxidase (GOx) anchoring (DMSN-Cu@GOx/PEG). DMSN-Cu@GOx/PEG was further encapsulated in a thermal-sensitive hydrogel (H@DMSN-Cu@GOx/PEG). DMSN-Cu@GOx/PEG utilizes its high peroxidase (POD) activity to elevate intracellular ROS levels, thereby weakening the AR capability of bladder cancer cells. Additionally, through its excellent catalase (CAT) activity, DMSN-Cu@GOx/PEG converts the high level of hydrogen peroxide (H2O2) catalyzed by intracellular GOx into oxygen (O2), effectively alleviating tumor hypoxia, downregulating hypoxia-inducible factor-1α (HIF-1α) expression, inhibiting epithelial-mesenchymal transition (EMT) processes, and ultimately suppressing the migration and invasion of bladder cancer cells. Interestingly, in vivo results showed that the thermosensitive hydrogel H@DMSN-Cu@GOx/PEG could rapidly gel at body temperature, forming a gel film on wounds to eliminate residual tumor tissue after tumor resection surgery. Importantly, H@DMSN-Cu@GOx/PEG exhibited excellent hemostatic capabilities, effectively enhancing tissue coagulation during post-tumor resection surgery and mitigating the risk of cancer cell dissemination and recurrence due to surgical bleeding. Such hydrogels undoubtedly possess strong surgical application. Our developed novel nanosystem and hydrogel can inhibit the AR capability of tumor cells and prevent recurrence post-surgery. This study represents the first report of using dendritic mesoporous silica-based nanoreactors for inhibiting the AR capability of bladder cancer cells and suppressing tumor recurrence post-surgery, providing a new avenue for developing strategies to impede tumor recurrence after surgery.Graphical

Spraying zinc oxide nanoparticles on pistachios (Pistacia vera L.) for preservation in cold storage

ABSTRACT The ability of zinc oxide nanoparticles to extend the shelf life of fresh pistachios in polyethylene packages in cold storage was evaluated. Independent variables were the type and concentration of the disinfectant (0.5%, 1%, 1.5%, and 2% nano-ZnO and 2% peracetic acid) and storage time (at harvest, 25, 50 and 75 days after harvest). Aflatoxin was not detected in the kernels of the disinfectant treatments after storage. A decrease occurred in firmness, chlorophylls and carotenoids in hulls and kernels over time. Phenolics and flavonoids of kernels decreased, parallel to a decrease in weight. Nano-ZnO (2%) prevented this reduction well. In hulls and kernels, nano-ZnO (2%) revealed the highest anthocyanin. Antioxidant activity in kernels remained stable or even increased in response to ZnO (1.5%) on day 75. All ZnO treatments prevented ion leakage while limiting hydrogen peroxide and malondialdehyde production in hulls. Peracetic acid reduced polyphenol oxidase activity on 75th day. ZnO (1% and 1.5%) and peracetic acid increased phenylalanine ammonia lyase activity. On 75th day, ZnO-treated samples had higher peroxidase activity. All ZnO treatments, especially 1.5% and 2%, prevented the loss of quality in hulls, shells, taste, and aroma. Nano-ZnO (2%) can be recommended for fresh pistachio preservation in cold storage.

Construct a Magnetic Pt/Ru Alloy Peroxidase Mimic As a Reusable and Cost-Effective "Signal-Off" Sensing Platform for Sensitive and Wide-Linear-Range Assay.

"Signal-off" nanozyme sensing platforms are usually employed to detect analytes (e.g., ascorbic acid (AA) and alkaline phosphatase (ALP)), which are mostly based on oxidase (OXD) nanozymes. However, their drawbacks, like dissolved oxygen-dependent catalysis capability, relatively low enzyme activity, limited amount, and kind, may not favor sensing platforms' optimization. Meanwhile, with the need for sustainable development, a reusable "signal-off" sensing platform is essential for cutting down the cost of the assay, but it is rarely developed in previous studies. Magnetic peroxidase (POD) nanozymes potentially make up the deficiencies and become reusable and better "signal-off" sensing platforms. As a proof of concept, we first construct Fe3O4@polydopamine-supported Pt/Ru alloy nanoparticles (IOP@Pt/Ru) without stabilizers. IOP@Pt/Ru shows high POD activity with Vmax of 83.24 × 10-8 M·s-1 for 3,3',5,5'-Tetramethylbenzidine (TMB) oxidation. Meanwhile, its oxidation rate for TMB is slower than the reduction of oxidized TMB by reducers, favorable for a more significant detection signal. On the other hand, IOP@Pt/Ru possesses great magnet-responsive capability, making itself be recycled and reused for at least 15-round catalysis. When applying IOP@Pt/Ru for AA (ALP) detection, it performs better detectable adaptability, with a linear range of 0.01-0.2 mM (0.1-100 U/L) and a limit of detection of 0.01 mM (0.05 U/L), superior to most of OXD nanozyme-based ALP sensing platform. Finally, IOP@Pt/Ru's reusable assay was demonstrated in real blood samples for ALP assay, which has never been explored in previous studies. Overall, this study develops a reusable "signal-off" nanozyme sensing platform with superior assay capabilities than traditional OXD nanozymes, paves a new way to optimize nanozyme-based "signal-off" sensing platforms, and provides an idea for constructing inexpensive and sustainable sensing platforms.

Investigation of Seasonal Dynamism of Peroxidase from Strains of Aspergillus sp.

Peroxidases A and B production were carried out from Aspergillus tamari and fumigates respectively isolated from petroleum hydrocarbon spilled soil. Physicochemical properties of the respective soil showed pH of 4.45 and 6.5 for soils from point 1 and II respectively and higher conductivity of 613 and 1013 (Ω-1 Cm-1), respectively when compared with the control sample. Dissolved mineral of Cl-, SO4, K, Ca, Mg in the respective soil samples from the petroleum spilled sites was significantly high when compared with the control experiment except for soil sample I which showed a relative low phosphate concentration of 1,23 in the presence of the control experiment, respectively. TOC and TOM contents were 87.91, 119.04; 108.13 and 146.42 mg/g for soil sample I, and III, respectively. In all the tested parameters, the experimented soils were significantly high than the control soil sample. Molecular tests (18S rDNA.) were used to identify the pure isolates of Aspergillia. Studies on the effect of the incubation period on the production of peroxidase from strains of ofAspergillus tamarrii sp. and Aspergillusshowed that the highest peroxidase (A and B) activity representing peroxidase from dry and wet conditions were obtained on the day 6th and 5th of the fermentation time figure peroxidase A activity peaked at pH 5 while that of peroxidase B peaked at pH 6.0; proteins with highest peroxidase activity was peak precipitated at 60% and 80% saturation of the salt for peroxidase A and B, respectively. The gel chromatogram showed single almost superimposed peaks of enzyme activity for peroxidase A and B respectively. Peroxidase A and B activity peaked at pH 4.5 and 5.0. Optimum temperature for the enzyme activity was at 50 and 60°C respectively. Km and V max of 3.45mM and 280 μmole/min; 2.44mM and 305μmole/min were extrapolated from the reciprocal curve of Lineweaver-burke at various concentrations of 2,6 DMP for peroxidase A. Fe, Ca, Co and Mn selected as their notable impact in the active site of peroxidase guided the selected were assayed in the presence of the enzymes, respectively. The stability curve obtained for the peroxidases was single biphasic which represents the first order; Peroxidase B maintained greater stability than A at its optimum pH and pH 7. The enzymes maintained greater than 50% of their activity after 30 min of incubation as activity progressively decreased up to 40% after 60 min of incubation. Thermal stability of peroxidase A and B at their respective optimum temperatures (50 and 60°C) and at 70°C showed a biphasic stability curve of peroxidase A but single phase in peroxidase B. Peroxidase B maintained greater stability than A at its optimum temperature and at 70°C. The enzymes maintained greater than 50% of their activity after 60 min of incubation. Stability curve of peroxidase A and B at 70°C showed a maximum activity of the enzymes after 30 min of incubation. However, Peroxidase B maintained greater stability than A after 60 min of incubation. Peroxidase B maintained 57.89% of its activity after 60 min while peroxidase A from fig 19 showed a residual activity of 41.2%.

Photosynthetic Costs and Impact on Epidemiological Parameters Associated with Ht Resistance Genes in Maize Lines Infected with Exserohilum turcicum.

Northern corn leaf blight, caused by Exserohilum turcicum, is mainly controlled by the use of resistant cultivars. Maize lines carrying individual resistance genes B37Ht1, B37Ht2, B37Ht3, and B37Htn1 express different defense symptoms having an impact on the photosynthetic activity, the accumulation of reactive oxygen species, and epidemiological parameters. Plants were inoculated with a race 0 isolate of E.turcicum conferring a compatible interaction with B37 and incompatible interactions with plants carrying resistance genes. Five days postinoculation (dpi), the resistant lines displayed a reduction in leaf CO2 assimilation of 30 to 80% compared with healthy plants. At 14 dpi, inoculated plants of B37Ht1 showed a significant decrease in leaf CO2 assimilation, similar to B37 (up to 94%). The instantaneous carboxylation efficiency was significantly reduced on inoculated plants of the lines B37Ht2, B37Ht3, and B37Htn1 (54 to 81%) at 5 dpi. Curiously, the reduction in carboxylation efficiency for B37 and B37Ht1 (up to 95%) was higher at 14 dpi than at 5 dpi (up to 81%). At 6 dpi, low levels of H2O2 were detected in B37Ht1, in contrast to B37Htn1, where a high H2O2 level and peroxidase activity were observed. The sporulation rate on B37Ht1, B37Ht3, and B37Htn1 decreased by 92% compared with the susceptible control, whereas strong sporulation occurred in lesions on line B37Ht2. The resistance in maize to E. turcicum conferred by Ht resistance genes is associated with photosynthetic costs and may have quite contrasting effects on host physiology and major epidemiological parameters, such as sporulation, which contributes inoculum for secondary infections.

Temporal Changes in Biochemical Responses to Salt Stress in Three Salicornia Species.

Halophytes adapt to salinity using different biochemical response mechanisms. Temporal measurements of biochemical parameters over a period of exposure to salinity may clarify the patterns and kinetics of stress responses in halophytes. This study aimed to evaluate short-term temporal changes in shoot biomass and several biochemical variables, including the contents of photosynthetic pigments, ions (Na+, K+, Ca2+, and Mg2+), osmolytes (proline and glycine betaine), oxidative stress markers (H2O2 and malondialdehyde), and antioxidant enzymes (superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase) activities of three halophytic Salicornia species (S. persica, S. europaea, and S. bigelovii) in response to non-saline, moderate (300 mM NaCl), and high (500 mM NaCl) salinity treatments at three sampling times. Salicornia plants showed maximum shoot biomass under moderate salinity conditions. The results indicated that high Na+ accumulation in the shoots, coupled with the relative retention of K+ and Ca2+ under salt stress conditions, contributed significantly to ionic and osmotic balance and salinity tolerance in the tested Salicornia species. Glycine betaine accumulation, both constitutive and salt-induced, also seems to play a crucial role in osmotic adjustment in Salicornia plants subjected to salinity treatments. Salicornia species possess an efficient antioxidant enzyme system that largely relies on the ascorbate peroxidase and peroxidase activities to partly counteract salt-induced oxidative stress. The results also revealed that S. persica exhibited higher salinity tolerance than S. europaea and S. bigelovii, as shown by better plant growth under moderate and high salinity. This higher tolerance was associated with higher peroxidase activities and increased glycine betaine and proline accumulation in S. persica. Taking all the data together, this study allowed the identification of the biochemical mechanisms contributing significantly to salinity tolerance of Salicornia through the maintenance of ion and osmotic homeostasis and protection against oxidative stress.

Identification and characterization of lettuce cultivars with high inhibitory activity against the human pathogen Escherichia coli O157:H7: Toward a plant-intrinsic hurdle approach to microbial safety

Foodborne illness linked to fruit and vegetables poses a major challenge to public health and horticulture production. Processed lettuce has been implicated in recurrent outbreaks of pathogenic Shiga toxin-producing Escherichia coli (STEC) infection. We hypothesized that plant defenses elicited by mechanical injury may effect STEC inhibition in cut leaves. Intact and cut leaves of 31 lettuce cultivars (Lactuca spp.) selected from >500 accessions based on their resistance to common insect pests and the necrotrophic lettuce drop pathogen were assessed for STEC serovar O157:H7 (EcO157) survival under cold storage conditions. The cultivars were previously ranked also for phenotypes such as resistance to other phytopathogens and physiological traits. Total leaf phenolic compounds, anthocyanins, and reactive oxygen species (ROS); and phenylalanine lyase (PAL), peroxidase (POD), and polyphenol oxidase (PPO) activity were quantified in each cultivar. Principal Component Analysis (PCA) and K-means cluster analysis were applied to group phenotypes and EcO157 population decline on lettuce. In five cultivars, high resistance to herbivorous insects (aphids, leaf miners and thrips), diseases (lettuce drop, downy mildew, and Impatiens Necrotic Spot Virus), and the disorder tipburn was associated with up to 42-fold EcO157 population decline on cold-stored cut (shredded) leaves, and with up to 11-fold difference in decline on cold-stored intact vs cut leaves (ΔD). The decline on these cold-stored cut cultivars also was up to 24-fold greater than on the cultivar with the lowest decline, and up to 8-fold greater than the mean decline for all 31 cultivars (P < 0.01). Resistance to the hemibiotrophic pathogen causing lettuce bacterial leaf spot, Xanthomonas hortorum pv. vitians, was not indicative of high EcO157 inhibition in this system. High PAL activity, and phenolic and anthocyanin content (PPA); and high PAL and POD activity, were associated with high EcO157 population decline (P < 0.05). One cultivar with high susceptibility to herbivorous insects and phytopathogens, and low levels of defense metabolism nevertheless showed high EcO157 inhibition, suggesting other plant inhibitory characteristics at play. Basal plant immunity and pathways associated with a strong wound response may inform about enteric pathogen survival on minimally processed postharvest lettuce. The related traits identified in this study may serve to breed new genotypes with intrinsically enhanced microbial safety.

Natural Enzyme-Inspired Design of the Single-Atom Cu Nanozyme as Dual-Enzyme Mimics for Distinguishing Total Antioxidant Capacity and the Ascorbic Acid Level.

Although various oxidase mimetic or peroxidase (POD) mimetic nanozymes have been extensively studied, their poor substrate selectivity significantly inhibits their practical applications. Nanozymes with specific biomolecules as substrates, especially ascorbic acid oxidase (AAO) mimetic nanozymes with ascorbic acid (AA) as a substrate, have scarcely been studied. Herein, inspired by the multi-Cu atom sites and the redox electron transfer pathway of Cu2+/Cu+ in the natural AAO, atomically dispersed Cu sites immobilized on N-doped porous carbon (Cu-N/C) are artificially designed to simulate the function of natural AAO. Compared with their natural counterparts, the Cu-N/C catalysts exhibited higher catalytic efficiency and superior stability. Combined theoretical calculation and experimental characterizations reveal that the Cu-N/C nanozymes could catalyze the AA oxidation through a 2e- oxygen reduction pathway with H2O2 as the product. Moreover, the Cu-N/C nanozymes also possess high POD activity. As a proof-of-concept application, Cu-N/C can simultaneously realize AA detection in fluorescent mode based on its AAO activity and total antioxidant capacity detection in colorimetric mode utilizing its POD activity.

Trifunctional Nanocomposites with Colorimetric Magnetic Catalytic Activities Labels in Sandwich Immunochromatographic Detection of Escherichia coli O157:H7.

The emergence of nanoenzymes has catalyzed the robust advancement of the lateral flow immunoassay (LFIA) in recent years. Among them, multifunctional nanocomposite enzymes with core-shell architectures are considered preferable for promoting the sensing ability due to their good biocompatibility, precise control over size, and surface properties etc. Herein, we developed a dual-channel ensured lateral flow immunoassay (DFLIA) platform utilizing a magnetic, colorimetric, and catalytic multifunctional nanocomposite enzyme (Fe3O4@TCPP@Pd) [TCPP, Tetrakis (4-carboxyphenyl) porphyrin] for the ultrasensitive and highly accurate rapid detection of Escherichia coli O157:H7 (E. coli O157:H7). Fe3O4@TCPP@Pd-mAb exhibits superior performance compared to traditional AuNPs, including enhanced sensitivity and an extended linear detection range, benefiting from its high brightness signal, strong magnetic separation ability, and high peroxidase activity (Vmax = 2.32 μM S1-). Moreover, the Fe3O4@TCPP@Pd-labeled mAb probe exhibited exceptional stability and high affinity toward E. coli O157:H7 (with an affinity constant of approximately 1.723 × 109 M-1), indicating its potential for the efficient capture of the pathogen. Impressively, the developed Fe3O4@TCPP@Pd-DFLIA achieved ultrasensitive detection for E. coli O157:H7 with pre- and postcatalytic naked-eye detection sensitivities of 255 cfu/mL and 77 cfu/mL, respectively, representing an approximately 41-fold improvement over the conventional AuNP-based LFIA and also possessed good specificity and reproducibility [relative standard deviation (RSD) < 10%]. Additionally, the established DFLIA exhibited satisfactory recoveries in detecting pork and milk samples, further validating the reliability of this platform for immunoassays and demonstrating its potential for utilization in bioassays and clinical diagnostics.

Características do solo e morfofisiológicas de duas espécies de violeta (Viola sp.) influenciadas por ácido giberélico e nitrogênio

ABSTRACT Violet, with its pleasant scent and attractive flower color, is also important for its medicinal and edible uses, in addition to ornamental uses. Proper nutrition of the plant (violet) with essential nutrients and growth hormones improves the quantitative and qualitative characteristics and can increase the economic value and popularity of these flowers. In this regard, the current research aims to investigate the combined effect of nitrogen (N) and gibberellic acid (GA) on the morphophysiological traits of two native Iranian violet species (Viola tricolor and Viola odorata), as a factorial experiment with three factors including two species of violets, three levels of GA (0, 150 and 300 mg/L) and three levels of N (0, 100 and 200 mg/L) in a completely randomized design with 18 treatments, 3 replications and a total of 216 plants. Some characteristics of planting medium, morphophysiological traits and activity of antioxidant enzymes were evaluated. The results of ANOVA showed that the three-way effect of experimental treatments on all evaluated traits is significant. According to the results of comparing the averages the N application reduced the soil electrical conductivity (EC) versus its non-application in both violet species and at all GA levels. The highest soil N in both species was obtained from the application of 0 mg/L GA × 100 or 200 mg/L N. In two species of violets, the highest number of leaves, flowers, and stolons was obtained from the treatment of 300 mg/L GA × 200 mg/L N. The highest chlorophyll a and total chlorophyll among the treatments were related to V. odorata × 150 mg/L GA × 200 mg/L N. The application of GA and N in both species increased peroxidase activity versus the control. The highest level of this enzyme activity was related to 300 mg/L GA × 200 mg/L N. V. odorata had higher peroxidase activity than V. tricolor. The lowest and highest levels of catalase activity were recorded by control × V. tricolor (0.13 nM/g FW/min) and V. odorata × 300 mg/L GA × 200 mg/L N (0.676 nM/g FW/min), respectively. According to the results, with the application of 300 or 150 mg/L GA × 200 mg/L N, the ornamental and edible properties of these two types of violets are improved, and their economic value and marketability are increased, and there will be a change in the sales market of these flowers.

Treatment With Kiwi Peel Extract Delays Browning in Ready‐to‐Eat Lettuce

Browning reactions caused by oxidative stress occurring during postharvest procedures significantly compromise the quality of ready‐to‐eat (RTE) vegetables, negatively affecting their market value. Polyphenol oxidase (PPO) and peroxidase (POD) are two major enzymes involved in this phenomenon, as they oxidize phenolic compounds to quinones, which in turn polymerize to brown pigments. Recently, there has been an increasing interest in developing antibrowning treatments using food by‐products. Herein, the efficiency of a kiwi peel extract in reducing enzymatic browning of minimally processed lettuce (Lactuca sativa) has been investigated. PPO and POD activities showed an opposite spatial distribution within the leaf, with a higher POD activity in the midvein (MV) and in the inner lamina tissues, and a prevalence of PPO activity in the mesophyll. Considering that MV lignified tissues are those mainly affected by browning, the temporal trend of POD activity over a 20‐day storage period at 4°C was investigated. Data showed that treatment with a kiwi peel extract hinders both the increasing trend of POD activity and browning development compared to control leaves. These results could be potentially useful for the industry as they confirm that natural extracts, such as kiwi peel extract, can be valuable for extending the shelf‐life of RTE products.

The influence of microbial preparations on the biological activity of the rhizosphere and the productivity of winter triticale

The article presents the results on the effect of microbial preparations on the biological activity of the rhizosphere and the productivity of winter triticale. The microbiological and biochemical indicators of the biological activity of the winter triticale rhizosphere were studied against the background of the use of microbial preparations agrofil, mizorin, rhizobact of the RZHF brand and the FZhF brand. Data were revealed on the increase in the number of nitrogen-fixing microorganisms and actinomycetes when using agrofil, on the growth of micromycetes, actinomycetes, cellulose-decomposing microorganisms when treated with mizorin, the number of ammonifying microorganisms when treated with rhizobact preparations of the FZhF brand and the RZhF brand. Data on the beneficial effect of microbial preparations on the enzymatic pool of the winter triticale rhizosphere are presented. A high activity of phosphatase and peroxidase was noted when treated with the drug rhizobact brand FZhF, polyphenol oxidase and peroxidase when using the drug rhizobact brand RZHF, invertase and catalase when inoculated with the drug agrofil. Conclusions are formulated on the decrease in urease activity and the increase in indicators of productivity elements for all variants of the experiment.

Efficient conversion of tea residue nutrients: Screening and proliferation of edible fungi

Despite lignocellulose hindering the extraction of intracellular components, tea residue can serve as an excellent substrate for fungal fermentation owing to their lignocellulose-degrading abilities. Thus, the fermentation efficiencies of Lentinus edodes, Lentinus sajor-caju (Fr.), Flammulina filiformis, Hericium erinaceus, Pleurotus pulmonarius, and Monascus kaoliang B6 were evaluated using tea residue as a medium. P. pulmonarius and L. sajor-caju (Fr.) exhibited the fastest growth rates, with colony radii of 33.1 and 28.5 mm, respectively. M. kaoliang B6 demonstrated substantial degradation abilities for cellulose, hemicellulose, and lignin, with decolorization radii of 12.2, 0.9, and 8.5 mm, respectively. After a 9-days liquid fermentation, M. kaoliang B6 achieved the highest conversion efficiency at 27.8%, attributed to its high cellulase (191 U∙mL−1) and lignin peroxidase (36.9 U∙L−1) activities. P. pulmonarius and L. sajor-caju (Fr.) showed lower conversion rates of 8.6% and 3.8%, despite having high hemicellulase activities (67.1 and 70.9 U∙mL−1). Fermentation by M. kaoliang B6 resulted in a reduction of protein and total sugar content in the tea residue by 174 and 192 mg g−1, by which the mycelium's protein and total sugar content increased by 73 and 188 mg g−1. Co-fermentation of these three strains had little effect on the improvement of conversion efficiency, which might owe to the antagonistic interactions among the strains. Generally, utilizing tea residue for edible fungi fermentation is a sustainable process for bio-waste treatment, enabling efficient nutrient conversion under mild conditions without adding chemicals.

Morphophysiological features of the generative offspring of Aesculus hippocastanum L. from various ecologically unfavorable areas of an industrial city

The results of the influence of various ecological conditions of an industrial city (environmentally favorable zone, zones of motor vehicle emissions and metallurgical production, damage by the chestnut miner Cameraria ohridella Deschka &amp; Dimič) on the functional state of the generative offspring of Aesculus hippocastanum L. were given. The average degree of the mass variability of the horse chestnut seeds was revealed, the level of which depended on the type of pollution. Higher values of the variation coefficient were established in seeds from monitoring sites ecologically unfavorable for plant growth. A decrease in the mass of ripe seeds of horse chestnut exposed to the effects of vehicle emissions, metallurgical production, and the severe attack of the chestnut moth C. ohridella was shown compared to samples from an ecologically favorable zone. It was found that the moisture loss in seeds from the ecologically favorable zone was on average 25.0 %, while from the main road zone – 15.2 %. A decrease in the content of storage proteins by an average of 14.5 % in the zones of anthropogenic pollution was observed. The largest values of this characteristics were shown by most trees from the ecologically favorable zone. In the seeds of A. hippocastanum plants, an increase in the activity of both benzidine peroxidase and catalase was established mainly under the effects of aerotechnogenic pollution. The level of enzyme activity depended on the type of phytotoxic emissions. A decrease in the activity of benzidine peroxidase was registered due to the effects of motor vehicle emissions, and an increase due to the effects of metallurgical production. A significant increase in catalase activity was found in the seeds of A. hippocastanum trees from two monitoring sites and, especially, under the influence of vehicle emissions, which can be explained by a compensatory reaction in response to reduced peroxidase activity. An individual reaction of the studied protein system (storage proteins, antioxidant enzymes) of the seeds of some trees was observed, regardless of the stress level of technogenic load and the type of pollutants. At each monitoring site, trees whose seeds had both increased and significantly decreased enzyme activity were identified. In the Botanical Garden and in the park near the metallurgical enterprise, the seeds of only one of three trees showed high activity of both peroxidase and catalase. Considering the physiological functions of the studied enzymes in the seeds and the reaction of the plant organism to biotic and abiotic stresses, the increase in the activation of catalase and peroxidase indicated their participation in antioxidant protection against active forms of oxygen to ensure a reduction in the intensity of damage processes in the generative offspring of A. hippocastanum L. The variability of the level of enzyme activity in horse chestnut seeds means adaptation to environmental conditions and, in general, reveals the adaptive ability of generative offspring to germinate due to the high antioxidant potential to counteract the development of oxidative stress under the influence of adverse environmental factors. It was concluded that the chronic influence of adverse factors of the urban environment causes the formation of individual seeds with increased antioxidant protection characteristics, which can be used as planting material when creating sustainable plantations in an industrial city.