Polymer Microscopy

Sawyer, Linda C.; Grubb, D. T.

doi:10.1007/978-94-015-8595-8

Cited by 229 publications

(118 citation statements)

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“…If so, cryo-TEM can help to decide which model fits better in our case; while SAXS can provide an average of the feature size based on a relatively large sample volume, microscopy gives the local structural details. 34 As cryo-TEM indicates ( Figure 5), the micelles, at least partially, are clearly oblate-shaped, both when empty and when loaded with drug. Furthermore, there is sure evidence of growth in micelle volume and no implications of increased polydispersity upon drug loading.…”

Section: ■ Results and Discussionmentioning

confidence: 96%

Celecoxib Encapsulation in β-Casein Micelles: Structure, Interactions, and Conformation

et al. 2015

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β-Casein is a 24 kDa natural protein that has an open conformation and almost no folded or secondary structure, and thus is classified as an intrinsically unstructured protein. At neutral pH, β-casein has an amphiphilic character. Therefore, in contrast to most unstructured proteins that remain monomeric in solution, β-casein self-assembles into well-defined core-shell micelles. We recently developed these micelles as potential carriers for oral administration of poorly water-soluble pharmaceuticals, using celecoxib as a model drug. Herein we present deep and precise insight into the physicochemical characteristics of the protein-drug formulation, both in bulk solution and in dry form, emphasizing drug conformation, packing properties and aggregation state. In addition, the formulation is extensively studied in terms of structure and morphology, protein/drug interactions and physical stability. Particularly, NMR measurements indicated strong drug-protein interactions and noncrystalline drug conformation, which is expected to improve drug solubility and bioavailability. Small-angle X-ray scattering (SAXS) and cryogenic transmission electron microscopy (cryo-TEM) were combined for nanostructural characterization, proving that drug-protein interactions lead to well-defined spheroidal micelles that become puffier and denser upon drug loading. Dynamice light scattering (DLS), turbidity measurements, and visual observations complemented the analysis for determining formulation structure, interactions, and stability. Additionally, it was shown that the loaded micelles retain their properties through freeze-drying and rehydration, providing long-term physical and chemical stability. Altogether, the formulation seems greatly promising for oral drug delivery.

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Section: ■ Results and Discussionmentioning

confidence: 96%

Celecoxib Encapsulation in β-Casein Micelles: Structure, Interactions, and Conformation

et al. 2015

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“…Then, this technique permits to distinguish either the chemical or the physical incorporation of a heavy atom. The RuO 4 oxidizes aromatic rings yielding either mono‐ or dicarboxylic acids 22. In this case, the RuO 4 is used to stain mainly the PS aromatic rings.…”

Section: Resultsmentioning

confidence: 99%

Grafting of styrene onto polyethylene in near critical media

Martini

Brignole

Barbosa

2011

J of Applied Polymer Sci

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In this work, near critical n-heptane is used as reaction medium for the copolymerization of polyethylene with styrene monomer, using alkylation reaction with different amounts of aluminum chloride (AlCl 3 ) as catalyst. In this way, polyethylene chains will be more available to react with the catalyst. The reaction effect on pure reactants, as well as, the catalyst activity was previously investigated. The reaction occurrence was corroborated by analyzing the reaction products before and after careful polystyrene extraction with tetrahydrofuran. The reaction products were characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, scanning electron microscopy, transmission electron microscopy, differential scanning calorimetry, and size exclusion chromatography. The possible architecture for the copolymer molecule was proposed from the molecular characterization results. On the other hand, the polystyrene grafting modifies final properties of polyethylene, increasing the oxygen barrier properties without deteriorating significantly the mechanical properties of the films. In this sense this reaction seems to be a promising route to modify PE films to increase the barrier properties.

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“…In the case of n‐PET, the nanoparticles inhibit the formation of a crystalline lamellar structure and result in a lower crystallinity compared to PET. The typical size of the crystalline area is about 1 μm, and hence interference from the nanoparticles is possible …”

Section: Discussionmentioning

confidence: 99%

Crystalline structure and mechanical properties of poly(ethylene terephthalate) filament embedded with nanosize clay particles

Bahng

Endoh

Ryu

et al. 2018

J of Applied Polymer Sci

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The properties of poly(ethylene terephthalate) (PET) filaments embedded with nanosize clay powder were evaluated. The moisture management function and thermal properties of the textile were found to be improved; however, the strength of the filament was lowered with a little increase in elongation. In situ analysis of the crystalline structure with small-angle X-ray scattering and wide-angle X-ray diffraction during the tensile testing showed an unstable change in intensities during the elongation. This phenomenon is related to the earlier rearrangement and breaks down the microstructure in local regions with an increase in strain. This is expected to be due to the low adhesion strength between the matrix and the embedded nanosize clay particles. V C 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46321.

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Polymer Microscopy

Cited by 229 publications

References 0 publications

Celecoxib Encapsulation in β-Casein Micelles: Structure, Interactions, and Conformation

Celecoxib Encapsulation in β-Casein Micelles: Structure, Interactions, and Conformation

Grafting of styrene onto polyethylene in near critical media

Crystalline structure and mechanical properties of poly(ethylene terephthalate) filament embedded with nanosize clay particles

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