Enzyme-mimicking nanomaterials (nanozymes) are more cost-effective and robust than protein enzymes, but they lack specificity. Herein, molecularly imprinted polymers were grown on Fe3O4 nanozymes ...with peroxidase-like activity to create substrate binding pockets. Electron microscopy confirmed a shell of nanogel. By imprinting with an adsorbed substrate, moderate specificity was achieved with neutral monomers. Further introducing charged monomers led to nearly 100-fold specificity for the imprinted substrate over the nonimprinted compared to that of bare Fe3O4. Selective substrate binding was further confirmed by isothermal titration calorimetry. The same method was also successfully applied for imprinting on gold nanoparticles (peroxidase mimics) and nanoceria (oxidase mimics). Molecular imprinting furthers the functional enzyme mimicking aspect of nanozymes, and such hybrid materials will find applications in biosensor development, separation, environmental remediation, and drug delivery.
•Synergistic and additive effects of d-limonene and nisin were found.•Nisin enhances the antimicrobial activity of d-limonene and its nanoemulsion.•It causes the collapse of the cellular integrity ...and results lysis of the microbial cells.
d-Limonene has been considered to be a safer alternative compared to synthetic antimicrobial food additives. However, its hydrophobic and oxidative nature has limited its application in foods. The purpose of this research was to study effects of nisin on the antimicrobial activity of d-limonene and its nanoemulsion and develop a novel antimicrobial delivery system by combining the positive effect of these two antibacterial agents at the same time. By the checkerboard method, both the synergistic and additive effects of d-limonene and nisin were found against four selected food-related microorganisms. Then, d-limonene nanoemulsion with or without nisin was prepared by catastrophic phase inversion method, which has shown good droplet size and stability. The positive effects and outstanding antimicrobial activity of d-limonene nanoemulsion with nisin were confirmed by MICs comparison, scanning electron microscopy and determination of cell constituents released. Overall, the research described in the current article would be helpful in developing a more effective antimicrobial system for the production and preservation of foods.
A supramolecular gel formed by coordination of Zn(2+) with adenosine monophosphate (AMP) is reported. The adenine base, the monophosphate, and Zn(2+) are all important for gel formation. Mechanically ...disrupted gels can re-form upon centrifugation; applications of this gel for guest-molecule entrapment are explored.
Using molecular imprinting, a peroxidase‐mimicking DNAzyme has achieved substrate specificity with enhanced activity in a nanoscale gel for three different substrates.
High-frequency field nutrient analyzers offer a promising technology to solve time-consuming and laborious sampling problems in dynamic and complex river–estuarine–coastal ecosystems. However, few ...studies on the simultaneous underway analysis of five key nutrients (ammonium, nitrite, nitrate, phosphate, and silicate) in seawaters are available because of the limitations of the technique. In this study, a state-of-the-art autonomous portable analyzer for the shipboard analysis of nutrients in the environment of varied salinities and concentration ranges was reported. The analyzer consisted of compact hardware that was well suited for shipboard deployment with minimal maintenance. Moreover, a novel LabVIEW-based software program was developed, containing additional functions such as automated calibration curve generation, autodilution of high-concentration samples, and a user-friendly interface for multiparameter analysis using a single instrument. After the optimization of chemical reactions and work flow chart, the analyzer exhibited low limits of detection, a large linear range with automated dilution, and relative standard deviations of less than 2% (n = 11). Compared to other flow-based techniques, this analyzer is more portable and consumes less reagent with an autonomous data processing function and applicability within a broad salinity range (0–35). The analyzer was successfully applied for real-time analysis in the Jiulong River Estuary–Xiamen Bay with excellent on-site accuracy and applicability. The relationship between high spatial resolution nutrient concentrations and salinities showed very different patterns in estuarine and coastal areas, indicating the benefit of using an underway automated analyzer for chemical mapping in a dynamic environment.
Preserving enzyme activity and promoting synergistic activity via co-localization of multiple enzymes are key topics in bionanotechnology, materials science, and analytical chemistry. This study ...reports a facile method for co-immobilizing multiple enzymes in metal coordinated hydrogel nanofibers. Specifically, four types of protein enzymes, including glucose oxidase, Candida rugosa lipase, α-amylase, and horseradish peroxidase, were respectively encapsulated in a gel nanofiber made of Zn(2+) and adenosine monophosphate (AMP) with a simple mixing step. Most enzymes achieved quantitative loading and retained full activity. At the same time, the entrapped enzymes were more stable against temperature variation (by 7.5 °C), protease attack, extreme pH (by 2-fold), and organic solvents. After storing for 15 days, the entrapped enzyme still retained 70% activity while the free enzyme nearly completely lost its activity. Compared to nanoparticles formed with AMP and lanthanide ions, the nanofiber gels allowed much higher enzyme activity. Finally, a highly sensitive and selective biosensor for glucose was prepared using the gel nanofiber to co-immobilize glucose oxidase and horseradish peroxidase for an enzyme cascade system. A detection limit of 0.3 μM glucose with excellent selectivity was achieved. This work indicates that metal coordinated materials using nucleotides are highly useful for interfacing with biomolecules.
R2R3-MYB transcription factors are most abundant in the MYB superfamily, while the
genes play an important role in plant growth and development, especially in response to environmental stress.
is a ...multifunction tree species, and the existing resources cannot meet the requirement for its leaf production and medical use. Therefore, lands with some environmental stresses would be potential sites for developing
plantations. However, the function of
genes in
in response to environmental stress remains unknown. In this study, to identify the roles of
genes associated with salt stress response, 153
genes and their corresponding protein sequences were identified from the full-length transcriptome. Based on the comparison with MYB protein sequences of
, 69 R2R3-MYB proteins in
were extracted for further screening combined with conserved functional domains. Furthermore, the MYB family members were analyzed from the aspects of protein sequences alignment, evolution, motif prediction, promoter cis-acting element analysis, and gene differential expression under different salt treatments using both a pot experiment and hydroponic experiment. The results showed that the
genes of
conserved functional domains, whereas four
genes that might respond to salt stress via regulating plant hormone signals were identified in this study. This work provides a basis for further functional characterization of R2R3-MYB TFs in
.
As a multifunctional tree species,
Cyclocarya paliurus
leaves are rich in bioactive substances with precious healthy values. To meet the huge requirement of
C. paliurus
leaf production, sites with ...some environmental stresses would be potential land for developing its plantations due to the limitation of land resources in China. Nitric oxide (NO) and hydrogen sulfide (H
2
S) are common gas messengers used to alleviate abiotic stress damage, whereas the mechanism of these messengers in regulating salt resistance of
C. paliurus
still remains unclear. We performed a comprehensive study to reveal the physiological response and molecular regulatory mechanism of
C. paliurus
seedlings to the application of exogenous NO and H
2
S under salt stress. The results showed that the application of sodium hydrosulfide (NaHS) and sodium nitroprusside (SNP) not only maintained the photosynthetic capacity and reduced the loss of leaf biomass, but also promoted endogenous NO synthesis and reduced oxidative damage by activating antioxidant enzyme activity and increasing the content of soluble protein and flavonoids. Moreover, transcriptome and metabolome analysis indicated the expression of genes encoding phenylalanine ammonia lyase (PAL), cytochromeP450 (CYP), chalcone synthase (CHS), dihydroflavonol 4-reductase (DFR) and flavonol synthase (FLS) in flavonoid biosynthesis pathway was all up-regulated by the application of NO and H
2
S. Meanwhile, 15 transcriptional factors (TFs) such as WRKY, ERF, bHLH and HY5 induced by NO were found to regulated the activities of several key enzymes in flavonoid biosynthesis pathway under salt stress, via the constructed co-expression network. Our findings revealed the underlying mechanism of NO and H
2
S to alleviate salt stress and regulate flavonoid biosynthesis, which provides a theoretical basis for establishing
C. paliurus
plantations in the salt stress areas.
Older adults have a high prevalence of falls due to a decline in physiological functions and various chronic diseases. This study aimed to investigate the prevalence of and risk factors for falls ...among older individuals in the Chinese Longitudinal Healthy Longevity Survey (CLHLS). We collected information from 9737 older individuals (average age=84.26 years) from the CLHLS and used binary logistic regression analysis to explore the independent risk factors and protective factors for falls. The logistic regression analysis results are reported as adjusted odds ratios (aORs) and 95% confidence intervals (95%CIs). The prevalence of falls among older adults in China was 21.6%, with women (24.6%) having a higher prevalence than men (18.1%). Logistic regression analysis revealed that never (or rarely) eating fresh fruit, difficulty with hearing, cataracts, and arthritis were the common independent risk factors for falls in older Chinese men and women. Among men, age ≥80 years (aOR=1.86), never doing housework (aOR=1.36), and dyslipidemia (aOR=1.47) were risk factors, while eating milk products once a week was a protective factor. Alcohol consumption (aOR=1.40), physical labor (aOR=1.28), and heart disease (aOR=1.21) were risk factors for falls in women, while a daily sleep duration of 6-12 h and garlic consumption once a week were protective factors. The prevalence of falls among older adults in China is 21.6% and is greater in women than in men. These risk and protective factors can be used to formulate reasonable recommendations for living habits, diet, and chronic disease control strategies.
We report a simple and rapid saliva‐based SARS‐CoV‐2 antigen test that utilizes a newly developed dimeric DNA aptamer, denoted as DSA1N5, that specifically recognizes the spike proteins of the ...wildtype virus and its Alpha and Delta variants with dissociation constants of 120, 290 and 480 pM, respectively, and binds pseudotyped lentiviruses expressing the wildtype and alpha trimeric spike proteins with affinity constants of 2.1 pM and 2.3 pM, respectively. To develop a highly sensitive test, DSA1N5 was immobilized onto gold electrodes to produce an electrochemical impedance sensor, which was capable of detecting 1000 viral particles per mL in 1:1 diluted saliva in under 10 min without any further sample processing. Evaluation of 36 positive and 37 negative patient saliva samples produced a clinical sensitivity of 80.5 % and specificity of 100 % and the sensor could detect the wildtype virus as well as the Alpha and Delta variants in the patient samples, which is the first reported rapid test that can detect any emerging variant of SARS‐CoV‐2.
Rapid and simple: an electrochemical sensor, based on a high‐affinity dimeric DNA aptamer for the SARS‐CoV‐2 spike protein was developed to detect the wildtype and Alpha and Delta variant in unprocessed saliva samples in 10 minutes, providing a detection limit of 1000 copies mL−1, clinical sensitivity of 80.5 % and specificity of 100 %.
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