Novel Colloidal Assembly Methods for the Preparation of Core-Shell Composite Materials

2000 ◽  
Vol 636 ◽  
Author(s):  
Michael S. Fleming ◽  
Tarun K. Mandal ◽  
David R. Walt
Keyword(s):  
Electron Microscopy ◽  
Electrostatic Interactions ◽  
Physical Adsorption ◽  
Polymer Nanoparticles ◽  
Biological Interactions ◽  
Specific Chemical ◽  
Capillary Action ◽  
Colloidal Assembly ◽  
Transmission Electron ◽  
Shell Composite

AbstractColloidal assembly is a process by which particles ranging in size from nanometers to micrometers are organized into structures by mixing two or more particle types. Assembly is controlled by either specific or non-specific interactions between particles. Examples include chemical bonding, biological interactions, electrostatic interactions, capillary action and physical adsorption. The assembly process is performed such that smaller particles assemble around larger ones. In this paper, we report on colloidal assembly of polymer nanoparticles (50-200 nm diameter) onto silica particles (3-5 μm diameter) using specific chemical interactions (i.e. aminealdehyde). Annealing the assembled composites at temperatures above the glass transition (Tg) of the polymer nanospheres allows polymer to flow and uniformly coat the microsphere surfaces. Polystyrene and poly(methyl methacrylate) nanospheres were used to produce such materials. Shell composites were created by mixing both nanosphere types prior to assembly/annealing. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the materials presented herein.

Development of New Marker Compounds for the Detection of Chemical Element Labels by Electron Spectroscopic Imaging (ESI)

2001 ◽  
Vol 7 (S2) ◽  
pp. 1038-1039
Author(s):  
S. Raddatz ◽  
E. P. Mark ◽  
A. Haking ◽  
W. Probst ◽  
M. Wiessler ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Chemical Element ◽  
Three Dimensional ◽  
Point Of View ◽  
High Concentration ◽  
Specific Chemical ◽  
Energy Filtering ◽  
Transmission Electron ◽  
Gold Particle Size ◽  
Marker Compounds

A promising aspect of ESI is its application in the detection of elemental labels introduced into biomolecules for cell and molecular biological techniques. Even though colloidal gold labeling for electron microscopy (EM) is highly developed, availability of alternative labels, especially for double or triple labeling applications would be helpful because of difficulties with gold concerning i) detection (gold diameters ≤1nm), ii) discrimination due to gold particle size variations in one size class, and iii) different labeling efficiencies depending on gold granule size. An alternative labeling molecule should contain a high concentration of a specific chemical element which is not or in minor concentrations present in the system under surveillance, and has to have the potential to be discriminated from “biological” elements by ESI.With respect to ESI, one candidate for elemental labeling is boron. It meets the criteria described above and substantial experience in the synthesis of labeling compounds exists. From the chemical point of view, the preferred labeling structure is a so called dendrimer, a highly branched regular three-dimensional monodisperse macromolecule. Dendritic structures offer a large variety of functionalities to incorporate an element detectable by energy filtering transmission electron microscopy (EFTEM).

scholarly journals Nanohydrogels Based on Self-Assembly of Cationic Pullulan and Anionic Dextran Derivatives for Efficient Delivery of Piroxicam

Pharmaceutics ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 622 ◽  
Author(s):  
Dorota Lachowicz ◽  
Przemyslaw Mielczarek ◽  
Roma Wirecka ◽  
Katarzyna Berent ◽  
Anna Karewicz ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Self Assembly ◽  
Electrostatic Interactions ◽  
Dextran Sulfate ◽  
Force Microscopy ◽  
Grafting Reaction ◽  
Atomic Force ◽  
Transmission Electron ◽  
Efficient Delivery ◽  
Model Drug

A cationic derivative of pullulan was obtained by grafting reaction and used together with dextran sulfate to form polysaccharide-based nanohydrogel cross-linked via electrostatic interactions between polyions. Due to the polycation-polyanion interactions nanohydrogel particles were formed instantly and spontaneously in water. The nanoparticles were colloidally stable and their size and surface charge could be controlled by the polycation/polyanion ratio. The morphology of the obtained particles was visualized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). The resulting structures were spherical, with hydrodynamic diameters in the range of 100–150 nm. The binding constant (Ka) of a model drug, piroxicam, to the cationic pullulan (C-PUL) was determined by spectrophotometric measurements. The value of Ka was calculated according to the Benesi—Hildebrand equation to be (3.6 ± 0.2) × 103 M−1. After binding to cationic pullulan, piroxicam was effectively entrapped inside the nanohydrogel particles and released in a controlled way. The obtained system was efficiently taken up by cells and was shown to be biocompatible.

Synthesis of Ni-Mo-W Sulfide Nanorods as Catalyst for Hydrodesulfurization of Dibenzothiophene

2008 ◽  
Vol 8 (12) ◽  
pp. 6406-6413 ◽  
Author(s):  
F. Paraguay-Delgado ◽  
R. García-Alamilla ◽  
J. A. Lumbreras ◽  
E. Cizniega ◽  
G. Alonso-Núñez
Keyword(s):  
Electron Microscopy ◽  
Physical Adsorption ◽  
Atomic Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxide Precursor ◽  
Transmission Electron ◽  
Adsorption Of Nitrogen ◽  
Diffraction Patterns ◽  
Scanning Electron

Two trimetallic sulfurs, MoWNiS and MoWSNi, were synthesized to be used as a catalyst in hydrodesulfurization reactions. The mixed oxide mesoporous nanostructured MoO3-WO3 with an Mo:W atomic ratio of 1:1 was used as the precursor. The first catalyst was prepared by impregnating nickel in the oxide precursor and then subsequent sulfiding with an H2S/H2 mix at 400 °C for 2 hours. The second catalyst was prepared by sulfiding the precursor and then impregnating the nickel, and finally reducing the material with a H2/N2 at 350 °C. In both catalysts the Mo:W:Ni atomic ratio was maintained at 1:1:0.5. The materials obtained were characterized by physical adsorption of nitrogen, X-ray diffraction, scanning electron microscopy, transmission electron microscopy. Furthermore, the materials obtained were evaluated by a dibenzothiophene hydrodesulfuration reaction. The diffraction patterns show that both materials are polycrystalline and mainly of MoS2 and WS2 phases.

Preparation and Characterization of Platinum/Polyaniline Core-Shell Composite

2011 ◽  
Vol 347-353 ◽  
pp. 3302-3305
Author(s):  
Jing Na Zhu ◽  
Zhen Lu Shen ◽  
Wei Min Mo ◽  
Mei Chao Li
Keyword(s):  
Electron Microscopy ◽  
Interfacial Polymerization ◽  
Core Shell ◽  
The Core ◽  
Transmission Electron ◽  
Shell Composite ◽  
Synthesis Approach ◽  
Granular Morphology ◽  
Platinum Salt

Abstract. The core-shell composite of platinum/polyaniline (Pt@PAN) had been prepared by chemical synthesis approach. Reduction of the platinum salt in aqueous solution leaded to the formation of platinum nanoparticles, and then polyaniline were synthesized by interfacial polymerization to get Pt@PAN composite. Transmission electron microscopy of Pt@PAN showed Pt particles are uniform with spherical and granular morphology. Pt@PAN was also characterized by EDAX, XPS and FTIR.

Equilibrium, Kinetic and Thermodynamic Studies on Adsorptive Removal of H2S from Natural Gas by Amine Functionalisation of MCM-41

2017 ◽  
Vol 42 (3) ◽  
pp. 221-234 ◽  
Author(s):  
Jiao Jing Zhang ◽  
Wen Yi Wang ◽  
Guo Jian Wang ◽  
Cheng Kai ◽  
Hua Song ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Adsorption Isotherm ◽  
Natural Gas ◽  
Physical Adsorption ◽  
Oxygen Mixture ◽  
Impregnation Method ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Kinetic And Thermodynamic Studies ◽  
Mcm 41

A model natural gas consisting of hydrogen sulfide, nitrogen and oxygen mixture was used to simulate materials to test the performance of an amine-modified MCM-41 adsorbent prepared by the impregnation method. The adsorbent was characterised by X-ray diffraction analysis, Brunauer–Emmett–Teller analysis, Fourier-transform infrared spectroscopy, transmission electron microscopy and scanning electron microscopy. The results showed that more molecules are able to penetrate the pores following modification, resulting in rapid structural collapse, thus lowering the diffraction intensity. Although the capacity of amine-modified MCM-41 decreased the physical adsorption, chemisorption increased significantly. (3-Aminopropyl)trimethoxysilane/MCM-41 was found to exhibit a good performance for H2S desulfurisation. At 45 °C the breakthrough time was 186 min, the saturated sulfur capacity was 134.38 mg g−1 and the degree of desulfurisation was 54.19%. The adsorption isotherm and kinetics were investigated and the relevant parameters were obtained. The results showed that the adsorption isotherm could be well fitted by the Langmuir model and the maximum adsorption capacities increased with increase of temperature. The adsorption kinetics could be represented by the Bangham model, which suggested that chemical reaction seemed significant in the rate-controlling adsorption step. The adsorption process was spontaneous and exothermic.

scholarly journals Self-Assembly of Diphenylalanine-Based Nanostructures in Water and Electrolyte Solutions

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Sergio M. Acuña ◽  
María C. Veloso ◽  
Pedro G. Toledo
Keyword(s):  
Electron Microscopy ◽  
Self Assembly ◽  
Electrostatic Interactions ◽  
Hydrophobic Interactions ◽  
Electrolyte Solutions ◽  
Salt Solutions ◽  
Shape Information ◽  
Transmission Electron ◽  
Structure Breaking ◽  
Scanning Electron

Diphenylalanine (FF) is a peptide that can form different nanostructures; this makes it particularly attractive for both biological and technological applications. However, any application using this type of nanostructures requires controlling their size and shape. Information is provided about the various structures formed through the peptide FF self-assembly in different salt solutions (NaCl, CaCl2, and AlCl3), concentrations (50 mM, 100 mM, and 200 mM), and pH (3 to 10). Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Fourier-transform infrared (FTIR) spectroscopy were used to characterize the nanotubes. Results show that FF nanotube formation through self-assembly is a delicate balance between electrostatic, hydrogen bonding, and hydrophobic interactions; any imbalance in these can impede nanotube formation. Our results demonstrate that salts, such as NaCl and CaCl2, along with the studied concentrations promote the formation of very long nanotube agglomerates. This would be due to a combined screening effect and the fact that cations are structure-forming and promote hydrophobic interactions; therefore, nanotube agglomeration occurs and also benefits electrostatic interactions, hydrogen bonds, and longer nanotubes. The presence of AlCl3 produces an imbalance in the abovementioned interactions because of excess Cl-, a structure-breaking anion that impedes the nanostructure formation.

Immobilization of Porcine pancreatic Lipase on Vesicle-Like Silica Material with Large Pore

2012 ◽  
Vol 485 ◽  
pp. 314-317
Author(s):  
Cui Cui Wu ◽  
Guo Wei Zhou ◽  
De Lan Xu ◽  
Tian Duo Li
Keyword(s):  
Electron Microscopy ◽  
Cetyltrimethylammonium Bromide ◽  
Physical Adsorption ◽  
Sodium Dodecyl ◽  
Phosphate Buffer Solution ◽  
Buffer Solution ◽  
Excellent Thermal Stability ◽  
Silica Material ◽  
Transmission Electron ◽  
Adsorption Desorption

Vesicle-like silica (VS) was prepared by utilizing cationic surfactant cetyltrimethylammonium bromide (CTAB) and anionic surfactant sodium dodecyl sulfate (SDS) as a dual-template. The mesostructures of VS were characterized by N2adsorption-desorption isotherms, field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). Results showed that mean mesopore size of unilayer and multilayer VS was about 14 nm and shell thickness was nearly 6 nm. The VS was chosen as support for immobilization of Porcine pancreatic lipase (PPL) by physical adsorption. The immobilized PPL possessed excellent thermal stability and reusability in the hydrolysis reaction of triacetin in phosphate buffer solution.

scholarly journals Nitro-oxidized Carboxycellulose Nanofibers From Moringa Plant: Effective Bioadsorbent for Mercury Removal

2021 ◽  
Author(s):  
HUI CHEN ◽  
Sunil K. Sharma ◽  
Priyanka R. Sharma ◽  
Kai Chi ◽  
Eric Fung ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Drinking Water ◽  
Electrostatic Interactions ◽  
Mercury Contamination ◽  
X Ray Diffraction ◽  
Removal Capacity ◽  
Carboxylate Groups ◽  
Transmission Electron ◽  
Mineralization Processes ◽  
Contamination Problem

Abstract Mercury contamination in drinking water is a worldwide problem due to its severely harming effects on the human body. A nanostructured natural bioadsorbent, carboxycellulose nanofiber extracted from raw moringa plant using the nitro-oxidation method (termed NOCNF), capable of effectively remediating this problem has been demonstrated. Nitro-oxidation is a simple approach that can extract carboxylated nanocellulose directly from raw biomass. In this study, the produced NOCNF contained a large density of carboxylate groups on the cellulose surface (0.97 mmol/g), capable of removing Hg2+ ions by simultaneous electrostatic-interactions and mineralization processes. Using the Langmuir analysis, the adsorption results indicated that the highest Hg2+ removal capacity of this NOCNF was 257.07 mg/g, which is higher than most of the reported values. The interactions between Hg2+ and NOCNF were further characterized by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), transmission electron microscopy (TEM) with electron diffraction and wide-angle X-ray diffraction (WAXD) methods, suggesting the existence of two distinct removal mechanisms: predominant adsorption at low Hg2+concentrations (< 250 ppm) and predominant mineralization at high Hg2+ concentrations (> 1000 ppm). The applications of NOCNF were illustrated in both suspension form, as an adsorbent/coagulant, and dry powder form using filtration column. The results indicated that NOCNF in suspension exhibited a higher maximum removal efficiency of 81.6 % as compared to the dry state of 74.3 %. This work demonstrated the feasibility of extracting nanostructured adsorbents from biomass feedstocks to tackle the Hg2+ contamination problem in drinking water.

scholarly journals Facile Preparation of Carbon Nitride-ZnO Hybrid Adsorbent for CO2 Capture: The Significant Role of Amine Source to Metal Oxide Ratio

Catalysts ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1253
Author(s):  
Siti Aishah Anuar ◽  
Khairul Naim Ahmad ◽  
Ahmed Al-Amiery ◽  
Mohd Shahbudin Masdar ◽  
Wan Nor Roslam Wan Isahak
Keyword(s):  
Electron Microscopy ◽  
Metal Oxide ◽  
Photoelectron Spectroscopy ◽  
Physical Adsorption ◽  
Synthesis Method ◽  
Chemical Properties ◽  
Gaseous Fuel ◽  
X Ray ◽  
Transmission Electron ◽  
Adsorption Analysis

The presence of CO2 in gaseous fuel and feedstock stream of chemical reaction was always considered undesirable. High CO2 content will decrease quality and heating value of gaseous fuel, such as biohydrogen, which needs a practical approach to remove it. Thus, this work aims to introduce the first C3N4-metal oxide hybrid for the CO2 cleaning application from a mixture of CO2-H2 gas. The samples were tested for their chemical and physical properties, using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), physical adsorption analysis (BET), fourier-transform infrared (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The CO2 capacity test was carried out by means of a breakthrough test at 1 atm and 25° C using air as a desorption system. Among the samples, amine/metal oxide mass ratio of 2:1 (CNHP500-2(2-1)) showed the best performance of 26.9 wt. % (6.11 mmol/g), with a stable capacity over 6 consecutive cycles. The hybrid sample also showed 3 times better performance than the raw C3N4. In addition, it was observed that the hydrothermal C3N4 synthesis method demonstrated improved chemical properties and adsorption performance than the conventional dry pyrolysis method. In summary, the performance of hybrid samples depends on the different interactive factors of surface area, pore size and distribution, basicity, concentration of amine precursors, ratio of amines precursors to metal oxide, and framework stability.

scholarly journals Study on the Adsorption Properties of Iron Tailings for GO

Coatings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 768
Author(s):  
Jiawei Zhou ◽  
Liming Yao ◽  
Yunfeng Wang ◽  
Weiqi Zhao ◽  
Jiahui Gu
Keyword(s):  
Electron Microscopy ◽  
Aqueous Solutions ◽  
Photoelectron Spectroscopy ◽  
Adsorption Process ◽  
Physical Adsorption ◽  
Exothermic Reaction ◽  
Single Layer ◽  
X Ray ◽  
Force Microscopy ◽  
Transmission Electron

Iron tailings can be used as adsorbents to effectively remove graphene oxide (GO) in aqueous solutions. Experimental data show that pH, iron tailing quality, GO concentration and temperature have significant effects on the removal of GO, the adsorption of the tail involves a single layer adsorbed Langmuir model with exothermic reaction, and it compliance with the proposed dynamics model meets the requirements, the adsorption process is a spontaneous physical adsorption process. Combining scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) to analyze the iron tail according to the mechanisms of ore adsorption of GO, it was concluded that iron tailings might be a very promising material to effectively remove GO in aqueous solutions. The results of this research provide key information for the transportation and potential fate of GO in the natural environment.

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