Green Biosynthesis of Anisotropic Gold Nanoparticles Using Ampelopsis grossedentata Extract and their Shape-Controlled by Halogen

2016 ◽  
Vol 40 ◽  
pp. 128-135 ◽  
Author(s):  
Qing Quan Guo ◽  
Xin Fu Ma ◽  
Hai Xiang Ma ◽  
Yao Lu
Keyword(s):  
Electron Microscopy ◽  
Metallic Nanoparticles ◽  
Research Field ◽  
Synthesis Process ◽  
Halide Ions ◽  
Transmission Electron ◽  
Shape Controlled ◽  
Tea Extract ◽  
Ampelopsis Grossedentata ◽  
Anisotropic Gold Nanoparticles

The preparation of size- and shape- controlled metallic nanoparticles using biological methodologies is a noticeably stimulating research field due to their unique physicochemical properties. In this paper, biosynthesis of anisotropic AuNPs using Ampelopsis grossedentata extract and the effects of halide ions on the formation of AuNPs has been demonstrated. The sizes and morphologies of AuNPs were characterized by UV-vis-NIR spectrophotometer and Transmission Electron Microscopy (TEM). It showed that the shape, size and optical properties of AuNPs can be fine-tuned by varying the dosage of the vine tea extract. The presence of halogen ions has significantly influence the morphology of AuNPs during the synthesis process. Both of Br- and Cl- could produced nanoplates, whereas I- distorted the triangle nanoparticles to induce the formation of aggregated spherical ones.

scholarly journals Effects of Different Surfactant Charges on the Formation of Gold Nanoparticles by the LASiS Method

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2937
Author(s):  
Muhammad Zulfajri ◽  
Wei-Jie Huang ◽  
Genin-Gary Huang ◽  
Hui-Fen Chen
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Gold Nanoparticles ◽  
Laser System ◽  
Synthesis Process ◽  
Au Nps ◽  
Laser Fluences ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
532 Nm

The laser ablation synthesis in solution (LASiS) method has been widely utilized due to its significant prospects in laser microprocessing of nanomaterials. In this study, the LASiS method with the addition of different surfactant charges (cationic CTAB, nonionic TX-100, and anionic SDS) was used to produce Au NPs. An Nd:YAG laser system at 532 nm excitation with some synthetic parameters, including different laser fluences, ablation times, and surfactant concentrations was performed. The obtained Au NPs were characterized by UV-Vis spectroscopy, transmission electron microscopy, and zeta potential analyzer. The Au NPs exhibited the maximum absorption peak at around 520 nm for all samples. The color of Au NPs was changed from red to reddish by increasing the laser fluence. The surfactant charges also played different roles in the Au NPs’ growth during the synthesis process. The average sizes of Au NPs were found to be 8.5 nm, 5.5 nm, and 15.5 nm with the medium containing CTAB, TX-100, and SDS, respectively. Besides, the different surfactant charges induced different performances to protect Au NPs from agglomeration. Overall, the SDS and CTAB surfactants exhibited higher stability of the Au NPs compared to the Au NPs with TX-100 surfactant.

Synthesis of Trilaminar Core–Shell Au/α-Fe2O3@SnO2Nanocomposites and their Application for Nonenzymatic Dopamine Electrochemical Sensing

NANO ◽  
2019 ◽  
Vol 14 (11) ◽  
pp. 1950138 ◽  
Author(s):  
Sai Zhang ◽  
Shijun Yue ◽  
Jiajia Li ◽  
Jianbin Zheng ◽  
Guojie Gao
Keyword(s):  
Electron Microscopy ◽  
High Sensitivity ◽  
Electrochemical Sensing ◽  
Synthesis Process ◽  
Core Shell ◽  
X Ray Diffraction ◽  
X Ray ◽  
Long Term Stability ◽  
Transmission Electron

Au nanoparticles anchored on core–shell [Formula: see text]-Fe2O3@SnO2 nanospindles were successfully constructed through hydrothermal synthesis process and used for fabricating a novel nonenzymatic dopamine (DA) sensor. The structure and morphology of the Au/[Formula: see text]-Fe2O3@SnO2 trilaminar nanohybrid film were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The electrochemical properties of the sensor were investigated by cyclic voltammetry and amperometry. The experimental results suggest that the composites have excellent catalytic property toward DA with a wide linear range from 0.5[Formula: see text][Formula: see text]M to 0.47[Formula: see text]mM, a low detection limit of 0.17[Formula: see text][Formula: see text]M (S/[Formula: see text]) and high sensitivity of 397.1[Formula: see text][Formula: see text]A[Formula: see text]mM[Formula: see text][Formula: see text]cm[Formula: see text]. In addition, the sensor exhibits long-term stability, good reproducibility and anti-interference.

Optimal Sample Preparation to Characterize Corrosion in Historical Photographs with Analytical TEM

2014 ◽  
Vol 20 (5) ◽  
pp. 1585-1590
Author(s):  
Eva Grieten ◽  
Joost Caen ◽  
Dominique Schryvers
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Metallic Nanoparticles ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Soft Matrix ◽  
Transmission Electron ◽  
Traditional Preparation ◽  
Beam Transmission ◽  
Historical Photographs

AbstractAn alternative focused ion beam preparation method is used for sampling historical photographs containing metallic nanoparticles in a polymer matrix. We use the preparation steps of classical ultra-microtomy with an alternative final sectioning with a focused ion beam. Transmission electron microscopy techniques show that the lamella has a uniform thickness, which is an important factor for analytical transmission electron microscopy. Furthermore, the method maintains the spatial distribution of nanoparticles in the soft matrix. The results are compared with traditional preparation techniques such as ultra-microtomy and classical focused ion beam milling.

scholarly journals Investigation on Variables Contributing to the Synthesis of C-S-H/PCE Nanocomposites by Co-Precipitation Method

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7673
Author(s):  
Ziyang You ◽  
Jing Xu
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Precipitation Method ◽  
Synthesis Process ◽  
Orthogonal Experimental Design ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Ultra Fine Particle ◽  
Early Performance ◽  
Co Precipitation

The usage of nanoscale calcium silicate hydrate (nano C-S-H) proved to have an excellent promotion effect on the early performance of concrete as nano C-S-H with ultra-fine particle size can act as seeding for cement hydration. Therefore, it is of importance to tune the particle size during the synthesis process of nano C-S-H. In this paper, the influence of several variables of the particle size distribution (PSD) of nano C-S-H synthesized by chemical co-precipitation method with the aid of polycarboxylate (PCE) was studied by orthogonal experimental design. In addition, the composition, microstructure, and morphology of the C-S-H/PCE nanocomposites were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectrum. The results showed that the concentration of reactants had a significant impact on the PSD of C-S-H/PCE nanocomposites, followed by the dosage of dispersant. Ultrasonic treatment was effective in breaking the C-S-H/PCE aggregates with unstable agglomeration structures. The change in synthetic variables had a negligible effect on the composition of the C-S-H/PCE nanocomposites but had a significant influence on the crystallinity and morphology of the composites.

Transmission Electron Microscopy Study of Listeria monocytogenes Treated with Nisin in Combination with either Grape Seed or Green Tea Extract

2008 ◽  
Vol 71 (10) ◽  
pp. 2105-2109 ◽  
Author(s):  
T. SIVAROOBAN ◽  
N. S. HETTIARACHCHY ◽  
M. G. JOHNSON
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Listeria Monocytogenes ◽  
Green Tea ◽  
Morphological Changes ◽  
Grape Seed ◽  
Green Tea Extract ◽  
Transmission Electron ◽  
Phenolic Constituents ◽  
Tea Extract

The objective of this study was to use transmission electron microscopy to investigate the morphological changes that occurred in Listeria monocytogenes cells treated with grape seed extract (GSE), green tea extract (GTE), nisin, and combinations of nisin with either GSE or GTE. The test solutions were prepared with (i) 1% GSE, 1% GTE, 6,400 IU of nisin, and the combination of these dilutions with nisin or with (ii) the pure major phenolic constituents of GSE (0.02% epicatechin plus 0.02% catechin) or GTE (0.02% epicatechin plus 0.02% caffeic acid) and their combinations with 6,400 IU of nisin in tryptic soy broth with 0.6% yeast extract (TSBYE). Test solutions were inoculated with L. monocytogenes at approximately 106 CFU/ml and incubated for 3 or 24 h at 37°C. After 3 h of incubation, cells were harvested and evaluated under a transmission electron microscope (JEOL-100 CX) operating at 80 kV (50,000×). Microscopic examination revealed an altered cell membrane and condensed cytoplasm when L. monocytogenes cells were exposed to a combination of nisin with either GSE or GTE or to pure compounds of the major phenolic constituents in combination. After 24 h of incubation at 37°C, the combinations of nisin with GSE and nisin with GTE reduced the L. monocytogenes population to undetectable levels and 3.7 log CFU/ml, respectively. These observations indicate that the combination of nisin with either GSE or GTE had a synergistic effect, and the combinations of nisin with the major phenolic constituents were most likely associated with the L. monocytogenes cell damage during inactivation in TSBYE at 37°C.

scholarly journals Au-Pd Bimetallic Nanocatalysts Incorporated into Carbon Nanotubes (CNTs) for Selective Oxidation of Alkenes and Alcohol

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1380
Author(s):  
Hamed M. Alshammari ◽  
Abdullah S. Alshammari ◽  
Jamal R. Humaidi ◽  
Salma A. Alzahrani ◽  
Mosaed S. Alhumaimess ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Benzyl Alcohol ◽  
Metallic Nanoparticles ◽  
Active Sites ◽  
Bimetallic Nanoparticles ◽  
Catalytic Performance ◽  
Transmission Electron ◽  
Nanocomposite Catalysts ◽  
Bimetallic Nanocatalysts

Although supported bimetallic nanoparticles (Au-Pd NPs) demonstrate outstanding efficiency, challenges appear for carbon supported small and stable bimetallic nanoparticles used in liquid-phase reactions. In this work, Au-Pd NPs were supported on two types of carbon nanotubes: CNTs decorated covalently with carboxylic acid groups (O-CNTs) and non-covalently with the conductive poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) polymer (P-CNTs). The Au-Pd NPs were prepared using the sol immobilization approach on the functionalized CNTs, and the effect of the utilized functionalization method on the properties of the immobilized metallic nanoparticles and the performance of the nanocomposite catalysts was investigated. The fabricated nanocomposites were characterized using Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, High-resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM). The catalytic performance of Au-Pd/O-CNTs and Au-Pd/P-CNTs was exploited for the oxidation of both cyclooctene and benzyl alcohol. Oxidation and polymer decoration directly led to an enhancement in the performance of CNTs catalysts. The nanocomposite catalyst with oxidized CNTs (Au-Pd/O-CNTs) was also found to be much more efficient and robust than that with polymer decorated CNTs (Au-Pd/P-CNTs). The enhancement in the oxidation of both cyclooctene and benzyl alcohol on Au-Pd/O-CNTs is attributed to the well-dispersed and smaller Au-Pd NPs as active sites on the surface of O-CNTs as compared to the P-CNTs surface.

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