scholarly journals Infuence of Microstructure in Drug Release Behavior of Silica Nanocapsules

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Gema Gonzalez ◽  
Amaya Sagarzazu ◽  
Tamara Zoltan
Keyword(s):  
Pore Size ◽  
Drug Loading ◽  
Morphological Characteristics ◽  
Nitrogen Adsorption ◽  
Release Process ◽  
Al Content ◽  
Surface Areas ◽  
Transmission Electron ◽  
Good Potential ◽  
Model Drug

Meso- and nanoporous structures are adequate matrices for controlled drug delivery systems, due to their large surface areas and to their bioactive and biocompatibility properties. Mesoporous materials of type SBA-15, synthesized under different pH conditions, and zeolite beta were studied in order to compare the different intrinsic morphological characteristics as pore size, pore connectivity, and pore geometry on the drug loading and release process. These materials were characterized by X-ray diffraction, nitrogen adsorption, scanning and transmission electron microscopy, and calorimetric measurements. Ibuprofen (IBU) was chosen as a model drug for the formulation of controlled-release dosage forms; it was impregnated into these two types of materials by a soaking procedure during different periods. Drug loading and release studies were followed by UV-Vis spectrophotometry. All nano- and mesostructured materials showed a similar loading behavior. It was found that the pore size and Al content strongly influenced the release process. These results suggest that the framework structure and architecture affect the drug adsorption and release properties of these materials. Both materials offer a good potential for a controlled delivery system of ibuprofen.

Tailoring the Pore Size of Hypercrosslinked Polymer Foams

1996 ◽  
Vol 431 ◽  
Author(s):  
W. P. Steckle ◽  
M. A. Mitchell ◽  
P. G. Apen
Keyword(s):  
Pore Size ◽  
Polyaromatic Hydrocarbons ◽  
Crosslinking Agent ◽  
Nitrogen Adsorption ◽  
Total Surface Area ◽  
Pore Sizes ◽  
Surface Areas ◽  
Small Pore ◽  
High Resolution Tem ◽  
Cure Time

AbstractOrganic analogues to inorganic zeolites would be a significant step forward in engineered porous materials and would provide advantages in range, selectivity, tailorability and processing. Rigid molecular foams or “organic zeolites” would not be crystalline materials and could be tailored over a broader range of pore sizes and volumes. A novel process for preparing hypercrosslinked polymeric foams has been developed via a Friedel-Crafts polycondensation reaction. A series of rigid hypercrosslinked foams have been prepared using simple rigid polyaromatic hydrocarbons including benzene, biphenyl, m-terphenyl, diphenylmethane, and polystyrene, with p-dichloroxylene (DCX) or divinylbenzene (DVB) as the crosslinking agent. Transparent gels are formed suggesting a very small pore size. After drying the foams are robust and rigid. Densities of the resulting foams can range from 0.15g/cc to 0.75g/cc. Nitrogen adsorption studies have shown that by judiciously selecting monomers and crosslinking agent along with the level of crosslinking and the cure time of the resulting gel, the pore size, pore size distribution, and the total surface area of the foam can be tailored. Surface areas range from 160 to 1,200 m2/g with pore sizes ranging from 6Å to 2,000Å. Further evidence of the uniformity of the foams and their pore sizes has been confirmed by high resolution TEM.

Positron Annihilation Study of Porous ZnO Synthesized with Soft Template

2017 ◽  
Vol 373 ◽  
pp. 299-302
Author(s):  
Bo Zhou ◽  
Chong Yang Li ◽  
Ning Qi ◽  
Zhi Quan Chen
Keyword(s):  
Pore Size ◽  
Positron Lifetime ◽  
Nitrogen Adsorption ◽  
Soft Template ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Long Lifetime ◽  
Positron Annihilation Study ◽  
Adsorption Desorption

Porous ZnO were synthesized with soft template method using zinc acetate Zn (CH3COO)2·2H2O as precursor and block copolymer F127 as the surfactant. Nitrogen adsorption-desorption measurements indicate that the ZnO sample contains large pores with mean diameter of about 30 nm. However, both small-angle X-ray diffraction and transmission electron microscope measurements indicate that the pore ordering is missing. Positron lifetime measurements reveal two long lifetime components in the porous ZnO. The longest lifetime τ4 (75 ns) corresponds to ortho-positronium (o-Ps) annihilation in large pores. The pore size estimated from τ4 is about 10.6 nm. This is much smaller than that estimated from Nitrogen adsorption-desorption measurements. In addition, the intensity I4 is only about 2.2%. This is probably due to the chemical quenching and/or inhibition of positronium formation induced by ZnO, which reduces o-Ps lifetime and intensity, and leads to under estimation of the pore size.

scholarly journals Effect of Aluminum Incorporation into Mesoporous Aluminosilicate Framework on Drug Release Kinetics

2017 ◽  
Vol 2017 ◽  
pp. 1-9
Author(s):  
Raul-Augustin Mitran ◽  
Daniela Berger ◽  
Jeanina Pandele-Cusu ◽  
Cristian Matei
Keyword(s):  
Pore Size ◽  
Therapeutic Agent ◽  
Release Kinetics ◽  
Nitrogen Adsorption ◽  
Incipient Wetness Impregnation ◽  
X Ray Diffraction ◽  
Drug Molecules ◽  
Model Drug ◽  
Adsorption Desorption

Mesoporous silica materials are promising nanocarriers for the development of drug delivery systems. In this study, the influence of pore size, volume, surface area, and doping the silica framework on the release kinetics of a model drug, metoprolol, has been studied. 20% or 50% wt. therapeutic agent was loaded into the carrier mesopores through incipient wetness impregnation. The carriers and drug-loaded samples have been characterized by small- and wide-angle X-ray diffraction, FT-IR spectroscopy, scanning electron microscopy, and nitrogen adsorption-desorption isotherms. The in vitro release profiles have been fitted using a three-parameter kinetic model and they have been explained in terms of the release rate during the burst and sustained release stages and the fraction of drug molecules released during the burst stage. The silica framework doping with aluminum was found to decrease the amount of drug released in the burst stage, without affecting the other kinetic parameters. The therapeutic agent release rates depend mainly on the pore size and volume of the mesoporous carriers and drug-loaded samples.

scholarly journals Supramolecular Reinforcement of a Large Pore 2D Covalent Organic Framework

2021 ◽  
Author(s):  
Shashini Diwakara ◽  
Whitney Ong ◽  
Yalini Wijesundara ◽  
Robert Gearhart ◽  
Fabian Herbert ◽  
...  
Keyword(s):  
Pore Size ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Nitrogen Adsorption ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Structural Reinforcement ◽  
Transmission Electron ◽  
Covalently Linked ◽  
Green Fluorescent

Two dimensional covalent organic frameworks (2D-COFs) are a class of crystalline porous organic polymers that consist of covalently linked, two dimensional sheets that can stack together through non-covalent interactions. Here we report the synthesis of a novel COF, called PyCOFamide, which has an experimentally observed pore size that is greater than 6 nm in diameter. This is among the largest pore size reported to date for a 2D-COF. PyCOFamide exhibits permanent porosity and high crystallinity as evidenced by the nitrogen adsorption, powder X-ray diffraction, and high-resolution transmission electron microscopy. We show that the pore size of PyCOFamide is large enough to accommodate fluorescent proteins such as Superfolder green fluorescent protein and mNeonGreen. This work demonstrates the utility of non-covalent structural reinforcement in 2D-COFs to produce larger, persistent pore sizes than previously possible.

scholarly journals Comparison of Mercury Intrusion and Nitrogen Adsorption Measurements for the Characterization of Certain Natural Raw Materials Deposits

2010 ◽  
Vol 7 (1) ◽  
pp. 621-630
Author(s):  
Baghdad Science Journal
Keyword(s):  
Pore Size ◽  
Gas Adsorption ◽  
Raw Materials ◽  
Mercury Porosimetry ◽  
Construction Materials ◽  
Nitrogen Adsorption ◽  
Distribution Data ◽  
Active Components ◽  
Surface Areas ◽  
Wide Range

The porosity of materials is important in many applications, products and processes, such as electrochemical devices (electrodes, separator, active components in batteries), porous thin film, ceramics, soils, construction materials, ..etc. This can be characterized in many different methods, and the most important methods for industrial purposes are the N2 gas adsorption and mercury porosimetry. In the present paper, both of these techniques have been used to characterize some of Iraqi natural raw materials deposits. These are Glass Sand, Standard Sand, Flint Clay and Bentonite. Data from both analyses on the different types of natural raw materials deposits are critically examined and discussed. The results of specific surface areas showed considerable difference between the two sets of data on the same material. This indicates that the material have an external surface which can not be measure by mercury porosimeter. Also pore size distribution data obtained from N2 adsorption measurements shows a wide range of the smallest pore size. This result suggests that materials have micropores using IUPAC definitions of pore size.

scholarly journals Correlation of Morphology and In-Vitro Degradation Behavior of Spray Pyrolyzed Bioactive Glasses

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3703 ◽  
Author(s):  
Fetene Fufa Bakare ◽  
Yu-Jen Chou ◽  
Yu-Hsuan Huang ◽  
Abadi Hadush Tesfay ◽  
Toshihiro Moriga ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Particle Morphology ◽  
Nitrogen Adsorption ◽  
Bone Tissue Regeneration ◽  
Degradation Behavior ◽  
Surface Areas ◽  
Transmission Electron ◽  
Spray Pyrolysis Process ◽  
Adsorption Desorption

Bioactive glass (BG) is considered to be one of the most remarkable materials in the field of bone tissue regeneration due to its superior bioactivity. In this study, both un-treated and polyethylene glycols (PEG)-treated BG particles were prepared using a spray pyrolysis process to study the correlation between particle morphology and degradation behavior. The phase compositions, surface morphologies, inner structures, and specific surface areas of all BG specimens were examined by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption/desorption, respectively. Simulated body fluid (SBF) immersion evaluated the assessments of bioactivity and degradation behavior. The results demonstrate three particle morphologies of solid, porous, and hollow factors. The correlation between porosity, bioactivity, and degradation behavior was discussed.

Effects of Mixed Template on Pore Structure of Order of Crack-Free Monolithic Mesoporous Carbon

2014 ◽  
Vol 926-930 ◽  
pp. 85-88
Author(s):  
Jian Jiao ◽  
Yong Hong Cui ◽  
Yu Cai ◽  
Pan Pan Lv
Keyword(s):  
Pore Size ◽  
Mesoporous Carbon ◽  
Triblock Copolymer ◽  
Pore Diameter ◽  
Nitrogen Adsorption ◽  
Molar Ratio ◽  
Element Analysis ◽  
Resorcinol Formaldehyde ◽  
Transmission Electron ◽  
Mixed Template

Crack-free monolithic mesoporous carbon with worm-like structure has been synthesized by low-temperature autoclaving that use triblock copolymer F127 or P123 as composite template, and resorcinol-formaldehyde resol as carbon precursor. The effects of the composite template ratio on the structure of mesoporous carbon were studied by transmission electron microscopy, nitrogen adsorption measurements and element analysis. The results indicated that mesoporous carbon are worm-like structure when use F127/P123 as composite template. Compared mesoporous carbon synthesized by a single template, the pore size distribution of the mesoporous carbon synthesized by the composite template are directly affected by the molar ratio of P123 in the composite templates, however, the pore size is significantly enlarged when using F127/P123 as template. The pore size of mesoporous carbon increased to 12.0nm when the molar ratio of P123 in the composite templates is 67%. We achieved adjustable pore diameter by use F127/P123 changing the molar ratio of P123 in the composite templates.

In situ REM imaging of surface processes on ceramic bulk crystals from 300 to 1670 K in a conventional TEM

1991 ◽  
Vol 49 ◽  
pp. 660-661
Author(s):  
Z. L. Wang ◽  
J. Bentley
Keyword(s):  
High Temperatures ◽  
Image Resolution ◽  
Atomic Processes ◽  
Crystal Surfaces ◽  
Beam Radiation ◽  
Surface Areas ◽  
Transmission Electron ◽  
Reflection Electron Microscopy ◽  
Gas Reactions

Studying the behavior of surfaces at high temperatures is of great importance for understanding the properties of ceramics and associated surface-gas reactions. Atomic processes occurring on bulk crystal surfaces at high temperatures can be recorded by reflection electron microscopy (REM) in a conventional transmission electron microscope (TEM) with relatively high resolution, because REM is especially sensitive to atomic-height steps.Improved REM image resolution with a FEG: Cleaved surfaces of a-alumina (012) exhibit atomic flatness with steps of height about 5 Å, determined by reference to a screw (or near screw) dislocation with a presumed Burgers vector of b = (1/3)<012> (see Fig. 1). Steps of heights less than about 0.8 Å can be clearly resolved only with a field emission gun (FEG) (Fig. 2). The small steps are formed by the surface oscillating between the closely packed O and Al stacking layers. The bands of dark contrast (Fig. 2b) are the result of beam radiation damage to surface areas initially terminated with O ions.

scholarly journals Microstructure and Photothermal Conversion Performance of Ti/(Mo-TiAlN)/(Mo-TiAlON)/Al2O3 Selective Absorbing Film for Non-Vacuum High-Temperature Applications

2020 ◽  
Vol 11 (1) ◽  
pp. 124
Author(s):  
Haibin Geng ◽  
Hanzhe Ye ◽  
Xingliang Chen ◽  
Sibin Du
Keyword(s):  
Visible Light ◽  
Near Infrared ◽  
Substitutional Solid Solution ◽  
Experimental Conditions ◽  
Al Content ◽  
Spectrum Range ◽  
Light Interference ◽  
Transmission Electron ◽  
Conversion Performance ◽  
Columnar Grain

This paper aims to clarify the phase composition in each sub-layer of tandem absorber TiMoAlON film and verify its thermal stability. The deposited multilayer Ti/(Mo-TiAlN)/(Mo-TiAlON)/Al2O3 films include an infrared reflectance layer, light interference absorptive layers with different metal doping amounts, and an anti-reflectance layer. The layer thicknesses of Ti, Mo-TiAlN, Mo-TiAlON, and Al2O3 are 100, 300, 200, and 80 nm, respectively. Al content increases to 12 at.% and the ratio of N/O is nearly 0.1, which means nitride continuously changes to oxide. According to X-ray Diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) results, the diffraction peak that appears at 2θ = 40° demonstrates that Mo element aggregates in the substitutional solid solution (Ti,Al)(O,N) columnar grain. TiMoAlON films have low reflectivity in the spectrum range of 300–900 nm. When Al content is more than 10 at.%, absorptivity is almost in the spectrum range from visible to infrared, but absorptivity decreases in the ultraviolet spectrum range. When Al content is increased to 12 at.%, absorptivity α decreases by 0.05 in the experimental conditions. After baking in atmosphere at 500 °C for 8 h, the film has the highest absorptivity when doped with 2 at.% Mo. In the visible-light range, α = 0.97, and in the whole ultraviolet-visible-light near-infrared spectrum range, α = 0.94, and emissivity ε = 0.02 at room temperature and ε = 0.10 at 500 °C.

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