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An estimated 35% of the world's population depends on wheat as their primary crop. One fifth of the world's wheat is utilized as animal feed, while more than two thirds are used for human consumption. Each year, 17–18% of the world's wheat is consumed by China and India. In wheat, spot blotch caused by Bipolaris sorokiniana is one of the major diseases which affects the wheat crop growth and yield in warmer and humid regions of the world. The present work was conducted to evaluate the effect of green synthesized silver nanoparticles on the biochemical constituents of wheat crops infected with spot blotch disease. Silver nanoparticles (AgNPs) were synthesized using Mangifera indica leaf extract and their characterization was performed using UV-visible spectroscopy, SEM, XRD, and PSA. Characterization techniques confirm the presence of crystalline, spherical silver nanoparticles with an average size of 52 nm. The effect of green synthesized nanoparticles on antioxidative enzymes, e.g., Superoxide dismutase (SOD), Catalase (CAT), Glutathione Reductase (GR), Peroxidase (POX), and phytochemical precursor enzyme Phenylalanine Ammonia-Lyase (PAL), and on primary and secondary metabolites, e.g., reducing sugar and total phenol, in Bipolaris sorokiniana infected wheat crop were studied. Inoculation of fungal spores was conducted after 40 days of sowing. Subsequently, diseased plants were treated with silver nanoparticles at different concentrations. Elevation in all biochemical constituents was recorded under silver nanoparticle application. The treatment with a concentration of nanoparticles at 50 pp min diseased plants showed the highest resistance towards the pathogen. The efficacy of the green synthesized AgNPs as antibacterial agents was evaluated against multi drug resistant (MDR) bacteria comprising Gram-negative bacteria Escherichia coli (n = 6) and Klebsiella pneumoniae (n = 7) and Gram-positive bacteria Methicillin resistant Staphylococcus aureus (n = 2). The results show promising antibacterial activity with significant inhibition zones observed with the disc diffusion method, thus indicating green synthesized M. indica AgNPs as an active antibacterial agent against MDR pathogens. [ABSTRACT FROM AUTHOR]

Brevibacterium frigoritolerans, a strain quite potential use in environmental pollution, is also able to degrade the pesticide phorate. Here, we report a strain isolated from radioactive soil in the Xinjiang Uygur Autonomous Region of China. The genome of strain GD44 encompasses 5,471,331 base pairs with a GC content of 40.42%. The sequence was assembled into 1985 open reading frames (ORFs) encoding 5053 proteins. Sequence analysis identified the genes encoding enzymes related to the degradation of organophosphorus compounds such as esterase, phosphotransferase, C–P lyase, and alkaline phosphatase. The nitrate reductase gene was also found in GD44, which was associated with biosynthesis of silver nanoparticles used for bacteriostat. In addition, Antibiotic Resistance Ontology (ARO) genes accounted for 10.6%, including the vancomycin resistance gene cluster. Therefore, the whole-genome sequence of B. frigoritolerans GD44 will be beneficial for identifying and analyzing genes utilized for soil remediation and antibacterial agent, which will provide genetic evaluation for potential application in the future. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) are widely used in many consumer products, whereas their environmental behaviors in natural aquatic systems remain unknown, especially in natural brackish media. Therefore, it is urgent to investigate the environmental fate of AgNPs in natural brackish waters. Here, we investigated the stability of citrate-coated AgNPs in natural brackish water collected from 6 different sites with distinct salinities in the Xinglinwan Reservoir, located in Xiamen City, southeast China. The obtained results showed that AgNP colloids remained stable in low-salinity waters, which was mainly determined by the effects of dissolved organic matter (DOM) promoting the stability of the nanoparticles. However, the environmental fate of AgNPs in high-salinity waters was dominated by the salinity or ionic strength, especially the free ion concentrations of Cl−, SO 4 2−, or S2−, resulting in rapid sedimentation and dissolution. In addition, both DOM and salinity contributed to the environmental behavior of AgNPs in moderate-salinity waters, ultimately resulting in either colloidal stability or sedimentation. Overall, these results may reveal that AgNPs remain relatively stable for a long period in low-salinity natural waters, and that the stability might gradually decrease as AgNPs are transferred from freshwaters through brackish waters and eventually end up in seawater along the bay. Our findings also further indicate that the toxicity and potential risks of AgNPs may present more serious threats to the environment and organisms in natural freshwaters than in natural estuarine systems or seawater. Image 1 [ABSTRACT FROM AUTHOR]

The development of precise detection methods with simply operation for pesticides in various environmental samples is a particular challenge. Here a highly sensitive surface-enhanced Raman scattering (SERS) approach for the selective detection of trace atrazine was proposed with R6G as a Raman reporter, which was adsorbed on silver nanoparticles modified carbon dots. The latter were prepared by the reduction of Ag+ by carbon dots. In the presence of atrazine, the aggregation of the modified carbon dots due to the interaction between silver nanoparticles and atrazine led to great enhancement of the SERS signal of R6G. Under optimal assay conditions, the limit of quantification was estimated to be 10 nM, which matched with the standard for drinking water quality of China and WHO defined limit. A good linear response to atrazine was found in the concentration range of 10–1000 nM with the relative standard deviations between 1.8% and 5.6%. The determination of atrazine in real water samples was also carried out to confirm the practicability of the proposed method, which showed the recoveries from 95% to 117.5%. The target induced aggregation for enhancing the signal offered great potential for sensitive on-site detection of atrazine in environments. Image 1 • Silver nanoparticles modified carbon dots was designed as the substrate of Raman reporter R6G. • The SERS substrate was prepared by the reduction of Ag+ by carbon dots. • The target induced aggregation of the modified carbon dots leads to great enhancement of SERS signal of R6G. • A SERS method is proposed for atrazine detection with a concentration range of 10–1000 nM. • The determination of atrazine in real water samples is carried out to confirm the practicability. [ABSTRACT FROM AUTHOR]

Introduction: Nanoparticles are now being viewed as fundamental or the basic building blocks of nanotechnology. The most significant property of nanoparticles is that they exhibit large surface area to volume ratio. The most efficient and effective nanoparticles today studied are the ones made of noble metals like that of silver (Ag), gold (Au), or platinum (Pt). The presence of biomolecules of the plant capped in AgNPs is found by Fourier transform-infrared analysis, shape and size, examined by scanning electron microscope (SEM) and X-ray diffraction (XRD). From XRD, the average size of AgNPs is found to be around 15 nm. Atomic force microscope proves to be very helpful in the determination and verification of various morphological features and parameters. Materials and Methods: Plant sample was collected from phytolabs and is extracted using aqueous method. 1 g of sample with water is boiled for 10 min at 55°C. The extract was filtered. To the filtrate, 1 molar silver nitrate solution was prepared. Overnight incubation was done in shake incubator. Results and Discussion: Ultraviolet spectroscopy was taken. The sample was taken at 200–800 nm. Out of which the peak was seen at 420 nm. Fourier transform infrared results confirm the presence of functional groups. SEM shows the image of synthesized silver nanoparticles from Phyllanthus emblica. The image clearly indicates the particle size range in 138 nm. Conclusion: Silver nanoparticles have been used as an antimicrobial agent in many industries. Products made from these are also approved by developed countries such as US, UK, and China. These antimicrobial activities are found useful for water treatment. Because of its ability to kill microorganisms, it offers an alternative to conventional methods and can be used in applications such as bandages, food and water storage, and pharmaceutical waste management. Furthermore, nanopaints are made using this. [ABSTRACT FROM AUTHOR]

Porcine reproductive and respiratory syndrome virus (PRRSV) causes serious impacts on livestock farms worldwide, especially in the big pig-raising country of China. Development of fast and accurate PRRSV assay is of great significance in early diagnosis of PRRSV infection, which helps control large-scale disease transmission. Herein, we develop a portable and universal colorimetric biosensor for rapid detection of PRRSV with a smartphone-based platform. In the presence of target sequence, a sandwich structure is formed to anchor polydopamine-silver nanoparticles with pH indicators on cotton swabs. The amplified visual information can be captured and analyzed for accurate quantification within the range from 10 pM to 1 μM. Excellent analytical results are also validated challenging real tissue samples from PRRSV infected pigs. Meanwhile, the biosensor can be extended for nervous necrosis virus (NNV) detection from Plectropomus leopardus, demonstrating its great universal utility. • A smartphone-based portable biosensor is developed for the detection of porcine reproductive and respiratory syndrome virus. • Polydopamine-silver nanoparticles provide multiple active sites to load pH indicators for signal enhancement. • Excellent analytical results are validated with challenging samples from infected pigs. [ABSTRACT FROM AUTHOR]

Despite the increasing knowledge on the discharge of silver nanoparticles (AgNPs) into the environment and their potential toxicity to microorganisms, the interaction of AgNPs with heavy metals remains poorly understood. This study focused on the effect of AgNPs on heavy metal concentration and form in sediment contaminated with heavy metals from the Xiangjiang River. The results showed that the concentration of Cu, Zn, Pb and Cd decreased and then increased with a change in form. The changes in form and concentrations of heavy metals in pore water suggested that Cu and Zn were more likely to be affected compared to Pb and Cd. The concentrations of Hg in sediment pore water in three AgNPs-dosed containers, increased greatly until they reached their peaks at 4.468 ± 0.133, 4.589 ± 0.235, and 5.083 ± 0.084 μg L −1 in Bare AgNPs, Citrate AgNPs and Tween 80 AgNPs, respectively. The measurements of Hg concentrations in the sediment pore water, combined with SEM and EDX analysis, demonstrated that added AgNPs stabilized in pore water and formed an amalgam with Hg 0 , which can affect Hg transportation over long distance. [ABSTRACT FROM AUTHOR]

Silk, as one of the representative artifacts of China, profoundly affects the communication between eastern and western civilizations, and dyes, as the color support of silks, reflected crucial historical, cultural and technological information. Surface enhanced Raman spectroscopy (SERS) characterized by vibrational information has been extensively employed in dye analysis. However, since natural plants with complex coloring compositions in ancient China were broadly applied in dying textiles, the existing SERS methods often misinterpret results in dye analysis. Besides, semi-quantification of each component was of great difficulty by SERS, limiting the exquisite comparative analyses of different historical samples. For the first time, a dual-mode strategy combining SERS with high mass resolution MALDI FTICR MS was developed in virtue of core-shell silver nanoparticles (AgNPs@PDA), which realized the precise identification and semi-quantification of complex dye mixtures, thus significantly improving the accuracy and applicability of traditional SERS method. Four typical dye components (alizarin, purpurin, berberine and indigo) have been identified and semi-quantified in unearthed dyed silks from Tang Dynasty based on the method. More interestingly, multiple dye components with different contents and their ratio could be precisely determined, which might help in further investigating their dyeing techniques. This dual-mode strategy represents a promising tool for providing solid support for cognition, evaluation and restoration of textile objects in museums and conservation centers. [Display omitted] • Core-shell AgNPs were used as both SERS enhancement reagent and MALDI matrix. • Multiple types of typical dyes were investigated through the dual-mode analysis. • Dye mixtures can be identified and semi-quantified based on the dual-mode strategy. • Four typical dye components were detected in ancient dyed silks from Tang Dynasty. [ABSTRACT FROM AUTHOR]

The toxicity of manufactured silver nanoparticles (AgNPs) has been widely studied, but the influence of AgNPs on the major ions (such as sodium [Na] and calcium [Ca]) regulations are unknown. In the present study, a freshwater cladoceran Daphnia magna was exposed to commercial AgNPs coated with polyvinylpyrrolidone. After 48 h, the Na body content was significantly reduced by AgNO3 exposure, but the Ca body content was significantly increased under AgNO3 and AgNP exposures, respectively. No effect was observed on the body concentrations of Na and Ca at 50 to 500 µg/L AgNPs with 1-µM cysteine addition. Exposure of AgNO3 and AgNPs inhibited the Na influx and elevated the Na efflux. In contrast, their exposure increased the Ca influx, but did not affect the Ca efflux. The results of the present study demonstrated the significant influences of AgNO3 and AgNPs (without cysteine) on Na and Ca regulations. Such effect of AgNPs on Na and Ca regulation disappeared after cysteine addition, indicating that the soluble Ag released from AgNPs played a major role in the ionoregulatory dysfunction. Environ. Toxicol. Chem. 2013;32:913-919. © 2013 SETAC [ABSTRACT FROM AUTHOR]

• Centimeter-scale high nanoscale roughness AuNPs/AgNWs composites were prepared. • The longest length is 5 cm and the diameters ranged from 50 nm to 100 nm. • Many 20–50 nm AuNPs existed on nanocomposites which lead to high roughness. • The limiting concentration of Rhodamine B for this SERS substrates is 10−15 mol/L. A novel centimeter-scale gold nanoparticles (AuNPs)/silver nanowires (AgNWs) composites surface-enhanced Raman scattering (SERS) substrates prepared by vacuum thermal evaporation and solid-state ionics method at 9 μA direct-current electric field (DCEF) with fast ionic conductor KAg 4 I 5 films was reported. The surface morphologies, microstructures and chemical compositions of the AuNPs/AgNWs composites were characterized. The fractal dimensions of centimeter-scale AuNPs/AgNWs composites was calculated by grid covering method and the SERS performance was detected by Rhodamine B (RB) aqueous solution as probe molecules. The results show that the macroscopic dendritic AuNPs/AgNWs composites with the longest length of 5 cm were prepared, the diameters of AuNPs/AgNWs composites changed from 50 nm to 100 nm and many 20–50 nm AuNPs existed on the prepared nanocomposites, which lead to high nanoscale roughness AuNPs/AgNWs composites. The molar ratio of Ag:Au is 28.67:1 and the fractal dimensions of AuNPs/AgNWs composites was 1.67 because of more dentritic nanocomposites. The limiting concentration of RB for the prepared SERS substrates is 10−15 mol/L, which is far below the strictest safety limits required of RB in China. These results show that the prepared AuNPs/AgNWs composites with high nanoscale roughness, facile material synthesis, low detection concentration and simple detection procedure has strong application prospect in food safety. [ABSTRACT FROM AUTHOR]

Biological fouling has caused a lot of concern in marine industries due to the attachment of microorganisms on marine surfaces. Silver nanoparticles (AgNPs) have a great potential to inhibit and hold strong toxicity against microorganisms on artificial surfaces immersed in seawater. In this study, AgNPs are synthesized using extract of clove buds (CE) plant as a reducing and stabilizing agent by biological synthesis method. The obtained CE-AgNPs product was characterized by using different techniques. Ultraviolet-visible spectroscopy (UV-Vis) results confirmed the formation of CE-AgNPs with its surface plasmon resonance peak range. Fourier-transform infrared spectroscopy (FTIR) study showed the formation of functional groups responsible for the reduction of Ag + into Ag o . X-Ray Diffraction (XRD) results revealed face-centered cubic (fcc) silver crystals having four different diffraction peaks at 38.08, 44.21, 64.42 and 77.32 with corresponding lattice plane value recorded at (111), (200), (220) and (311), respectively. Structural characterization using scanning electron microscopy equipped with energy dispersive X-Ray Analyzer (SEM-EDX), Transmission electron microscopy (TEM) and atomic force microscopy (AFM) also confirmed the successful formation of CE-AgNPs with fcc structure. The histogram of particle size distribution through TEM image showed an average size of 9.42 nm of the synthesized product. Finally, the antibacterial and antidiatom activity of the synthesized product was analyzed. The CE-AgNPs synthesized using CE possesses good inhibitory activity against the marine bacterium community and Nitzschia closterium diatom. These results indicate that CE-AgNPs can be used as a novel material for antibacterial and antidiatoms means to inhibit the biofouling on marine surfaces., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Bacterial stem and root rot disease of sweet potato caused by Dickeya dadantii recently broke out in major sweet potato planting areas in China and calls for effective approaches to control the pathogen and disease. Here, we developed a simple method for green synthesis of silver nanoparticles (AgNPs) using bacterial culture supernatants. AgNPs synthesized with the cell-free culture supernatant of a bacterium Pseudomonas rhodesiae displayed the characteristic surface plasmon resonance peak at 420–430 nm and as nanocrystallites in diameters of 20–100 nm determined by transmission electron microscopy, scanning electron microscopy, and X-ray diffraction spectroscopy. Functional groups associated with proteins in the culture supernatant may reduce silver ions and stabilize AgNPs. The AgNPs showed antibacterial activities against D. dadantii growth, swimming motility, biofilm formation, and maceration of sweet potato tubers whereas the culture supernatant of P. rhodesiae did not. AgNPs (12 µg∙ml−1) and AgNO3 (50 µg∙ml−1) showed close antibacterial activities. The antibacterial activities increased with the increase of AgNP concentrations. The green-synthesized AgNPs can be used to control the soft rot disease by control of pathogen contamination of sweet potato seed tubers. [ABSTRACT FROM AUTHOR]

The influence of silver nanoparticles (AgNPs) on the denitrification performance, enzyme activity, and functional gene relative abundances of sediment was investigated based on the methods of laboratory simulation incubation in the Dagu River estuary and bay area in the northwest of Jiaozhou Bay. The different dosages of AgNPs (i.e., 0, 135, and 1350 mg·L -1 in final concentration) was added to the incubation system containing surface sediments and in-situ bottom water. During six days' incubation, the concentrations of NO 3 - and NO 2 - , NO 3 - , and NO 2 - reductases activity, and relative abundances of narG and nirS genes were measured to explore the effects of AgNPs on denitrification and its mechanism. The results showed that AgNPs significantly inhibited NO 3 - and NO 2 - reductive capacity, NO 3 - and NO 2 - reductase activity, and narG and nirS gene relative abundances, which led to aggravated accumulation of NO 2 - . The inhibition of NO 2 - reductase was significantly greater than that of NO 3 - reductase, and the inhibition of the nirS gene was significantly higher than that of the narG gene. The inhibition of NO 3 - reduction was mainly ascribed to the inhibition of functional genes, but the inhibition of NO 2 - reduction was mainly due to the inhibition of reductase activity. The inhibition of NO 3 - and NO 2 - reductive capacity, NO 3 - reductase activity, and narG and nirS gene relative abundances in the northwest of Jiaozhou Bay was significantly higher than that in the Dagu River estuary.