Silver-cotton nanocomposites: Nano-design of microfibrillar structure causes morphological changes and increased tenacity.
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ABSTRACT:
SUBMITTER: Nam S
PROVIDER: S-EPMC5110977 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundBrassinosteroids (BRs) play crucial roles in drought tolerance, but the underlying molecular mechanisms remain unclear in the important oilseed and fiber crop, cotton (Gossypium hirsutum L.).ResultsTo elucidate how BRs mediate drought tolerance in cotton, a cotton brassinosteroid (BR)-deficient mutant, pag1 (pagoda1), was employed for analysis. Importantly, the pag1 mutant showed increased sensitivity to drought stress, with shorter primary roots and fewer lateral roots. The number of stomata was significantly increased in the mutant, and the stomata aperture was much wider than that of the control plants. These mutant plants therefore showed an increased water loss rate. Furthermore, the abscisic acid (ABA) content, photosynthetic efficiency and starch content of the mutant were significantly lower than those of the wild type. The overall performance of the mutant plants was worse than that of the wild-type control under both normal and drought conditions. Moreover, Proteomic analysis revealed reduced levels of stress-related proteins in pag1 plants.ConclusionsThese results suggest that BRs may modulate the drought tolerance of cotton by regulating much genes that related to drought stress and multiple organ responses to drought, including root growth, stomata development, the stomata aperture and photosynthesis. This study provides an important basis for understanding drought resistance regulated by BRs and cultivating drought-resistant cotton lines.
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Project description:In the last few years, we have witnessed significant progress in developing high performance shape memory polymer (SMP) nanocomposites, in particular, for shape recovery activated by indirect heating in the presence of electricity, magnetism, light, radio frequency, microwave and radiation, etc. In this paper, we critically review recent findings in Joule heating of SMP nanocomposites incorporated with nanosized conductive electromagnetic particles by means of nanoscale control via applying an electro- and/or magnetic field. A few different nanoscale design principles to form one-/two-/three- dimensional conductive networks are discussed.
| S-EPMC5452653 | biostudies-other
Project description:The use of nanomaterials alone or in composites with proteins is a promising alternative to inhibit pathogenic bacteria. In this regard, this study used seed proteins from both fenugreek (Trigonella foenum-graecum L.) (FNP) and mung bean (Viga radiate) (MNP), with silver nanoparticles (Ag-NPs) and nanocomposites of either Ag-NPs plus FNP (Ag-FNP) or Ag-NPs plus MNP (Ag-MNP) as inhibitory agents against pathogenic bacteria. FNP and MNP were isolated from fenugreek seeds and mung bean seeds, respectively, and fractionated using Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE). Both FNP and MNP were immobilized with Ag-NPs to synthesize the nanocomposites Ag-FNP and Ag-MNP, respectively. The physicochemical characteristics of Ag-NPs and their composites with proteins were studied by X-ray Diffraction (XRD), dynamic light scattering (DLS), the zeta potential, Scanning and Transmission Electron Microscopy (SEM and TEM, respectively), Atomic Force Microscopy (AFM), and the Brunauer-Emmett-Teller isotherm (BET), elucidating their structural parameters, size distribution, size charges, size surface morphology, particle shape, dimensional forms of particles, and specific surface area, respectively. The sole proteins, Ag-NPs, and their nanocomposites inhibited pathogenic Gram-positive and Gram-negative bacteria. The inhibitory activities of both nanocomposites (Ag-FNP and Ag-MNP) were more than those obtained by either Ag-NPs or proteins (FNP, MNP). Minimum inhibitory concentrations (MICs) of Ag-FNP were very low (20 and 10 µg mL-1) against Salmonellatyphimurium and Pseudomonasaerugenosa, respectively, but higher (162 µg mL-1) against E. coli and Listeriamonocytogenes. MICs of Ag-MNP were also very low (20 µg mL-1) against Staphylococcusaureus but higher (325 µg mL-1) against Listeriamonocytogenes. TEM images of Staphylococcusaureus and Salmonellatyphimurium, treated with Ag-FNP and Ag-MNP, at their MIC values, showed asymmetric, wrinkled exterior surfaces, cell deformations, cell depressions, and diminished cell numbers.
| S-EPMC8617916 | biostudies-literature
Project description:Multidrug-resistant organisms are increasingly implicated in acute and chronic wound infections, thus compromising the chance of therapeutic options. The resistance to conventional antibiotics demonstrated by some bacterial strains has encouraged new approaches for the prevention of infections in wounds and burns, among them the use of silver compounds and nanocrystalline silver. Recently, silver wound dressings have become widely accepted in wound healing centers and are commercially available. In this work, novel antibacterial wound dressings have been developed through a silver deposition technology based on the photochemical synthesis of silver nanoparticles. The devices obtained are completely natural and the silver coatings are characterized by an excellent adhesion without the use of any binder. The silver-treated cotton gauzes were characterized through scanning electron microscopy (SEM) and thermo-gravimetric analysis (TGA) in order to verify the distribution and the dimension of the silver particles on the cotton fibers. The effectiveness of the silver-treated gauzes in reducing the bacterial growth and biofilm proliferation has been demonstrated through agar diffusion tests, bacterial enumeration test, biofilm quantification tests, fluorescence and SEM microscopy. Moreover, potential cytotoxicity of the silver coating was evaluated through 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide colorimetric assay (MTT) and the extract method on fibroblasts and keratinocytes. Inductively coupled plasma mass spectrometry (ICP-MS) was performed in order to determine the silver release in different media and to relate the results to the biological characterization. All the results obtained were compared with plain gauzes as a negative control, as well as gauzes treated with a higher silver percentage as a positive control.
| S-EPMC5456794 | biostudies-other
Project description:Using medaka fish embryo model, toxic effects of silver nanocolloids (SNC, 3.8M-BM-11.0nm diameter) on developmental morphology and gene expression profile were investigated. SNC caused morphological changes in embryos including cardiovascular malformations, ischemia, underdeveloped central nervous system and eyes, and kyphosis at exposures of 0.5mg/L and 1.0mg/L.. To determine in vivo distribution of SNC, medaka embryos were exposed to 0.5mg/L for 6 days and subjected to ICP-OES analyses. Silver was detected in medaka embryos and chorion at levels of 16.6M-BM-19.3pg and 720M-BM-129pg, respectively. TEM analyses showed SNC adhered to the chorion surface and inside the chorion. On investigation of oxidative mechanism, NAC (0.05mM) rescued all embryos by 96-hr post treatment, while 0.5mM GSH did not. NAC blocked lipid peroxidation. Furthermore, medaka oligo DNA microarray and qRT-PCR were used for gene expression profiling in embryos exposed for 48-hr to 0.05mg/L SNC. Six genes relative to embryogenesis and morphogenesis such as ctsL, Tpm1, RBP, mt, atp2a1 and hox6b6 turned out to be affected and their involvement to the above malformations was implied. In conclusion, SNC causes gross malformations in the cardiovascular and central nervous systems in developing medaka embryos through potentially SNC-affected differential expression of a series of genes related to oxidative stress, embryonic cellular proliferation, and morphological development. Three of the stage-21 medaka embryos per sample were exposed in triplicate to 0mg/L (control) and 0.05mg/L SNC for 48 hours. Therefore, for each exposure condition nine of the stage-21 embryos were prepared and used in the SNC exposure test.
2012-06-16 | E-GEOD-33488 | biostudies-arrayexpress
Project description:Silver (Ag) is one of the seven metals of antiquity and an important engineering material in the electronic, medical, and chemical industries because of its unique noble and catalytic properties. Ag thin films are extensively used in modern electronics primarily because of their oxidation-resistance. Here we report a novel phenomenon of Ag nano-volcanic eruption that is caused by interactions between Ag and oxygen (O). It involves grain boundary liquation, the ejection of transient Ag-O fluids through grain boundaries, and the decomposition of Ag-O fluids into O2 gas and suspended Ag and Ag2O clusters. Subsequent coating with re-deposited Ag-O and the de-alloying of O yield a conformal amorphous Ag coating. Patterned Ag hillock arrays and direct Ag-to-Ag bonding can be formed by the homogenous crystallization of amorphous coatings. The Ag "nano-volcanic eruption" mechanism is elaborated, shedding light on a new mechanism of hillock formation and new applications of amorphous Ag coatings.
| S-EPMC5050507 | biostudies-literature
Project description:Using medaka fish embryo model, toxic effects of silver nanocolloids (SNC, 3.8±1.0nm diameter) on developmental morphology and gene expression profile were investigated. SNC caused morphological changes in embryos including cardiovascular malformations, ischemia, underdeveloped central nervous system and eyes, and kyphosis at exposures of 0.5mg/L and 1.0mg/L.. To determine in vivo distribution of SNC, medaka embryos were exposed to 0.5mg/L for 6 days and subjected to ICP-OES analyses. Silver was detected in medaka embryos and chorion at levels of 16.6±9.3pg and 720±29pg, respectively. TEM analyses showed SNC adhered to the chorion surface and inside the chorion. On investigation of oxidative mechanism, NAC (0.05mM) rescued all embryos by 96-hr post treatment, while 0.5mM GSH did not. NAC blocked lipid peroxidation. Furthermore, medaka oligo DNA microarray and qRT-PCR were used for gene expression profiling in embryos exposed for 48-hr to 0.05mg/L SNC. Six genes relative to embryogenesis and morphogenesis such as ctsL, Tpm1, RBP, mt, atp2a1 and hox6b6 turned out to be affected and their involvement to the above malformations was implied. In conclusion, SNC causes gross malformations in the cardiovascular and central nervous systems in developing medaka embryos through potentially SNC-affected differential expression of a series of genes related to oxidative stress, embryonic cellular proliferation, and morphological development.
2012-06-17 | GSE33488 | GEO
Project description:From an environmental and cost-effective perspective, a number of research challenges can be found for electronics, household, but especially in the automotive polymer parts industry. Reducing synthesis steps, parts coating and painting, or other solvent-assisted processes, have been identified as major constrains for the existing technologies. Therefore, simple polymer processing routes (mixing, extrusion, injection moulding) were used for obtaining PMMA/HNT nanocomposites. By these techniques, an automotive-grade polymethylmethacrylate (PMMA) was modified with halloysite nanotubes (HNT) and an eco-friendly additive N,N'-ethylenebis(stearamide) (EBS) to improve nanomechanical properties involved in scratch resistance, mechanical properties (balance between tensile strength and impact resistance) without diminishing other properties. The relationship between morphological/structural (XRD, TEM, FTIR) and tribological (friction) properties of PMMA nanocomposites were investigated. A synergistic effect was found between HNT and EBS in the PMMA matrix. The synergy was attained by the phase distribution resulted from the selective interaction between partners and favourable processing conditions. Modification of HNT with EBS improved the dispersion of nanoparticles in the polymer matrix by increasing their interfacial compatibility through hydrogen bonding established by amide groups with aluminol groups. The increased interfacial adhesion further improved the nanocomposite scratch resistance. The PMMA/HNT-EBS nanocomposite had a lower coefficient of friction and lower scratch penetration depth than PMMA/HNT nanocomposite.
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Project description:A novel plasmon-coupled quantum dot (QD) nanocomposite via covalently interfacing the QD surfaces with silver nanoparticles was developed with greatly reduced blinking and enhanced emission fluorescence.
| S-EPMC2737401 | biostudies-literature
Project description:We describe a new dichroic polarizers made by ordering silver nano-fibers to aligned layers. The aligned layers consist of nano-fibers and self-assembled molecular aggregates of lyotropic liquid crystals. Unidirectional alignment of the layers is achieved by means of mechanical shearing. Aligned layers of silver nano-fibers are partially transparent to a linearly polarized electromagnetic radiation. The unidirectional alignment and density of the silver nano-fibers determine degree of polarization of transmitted light. The aligned layers of silver nano-fibers might be used in optics, microwave applications, and organic electronics.
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