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Capsule Wall (capsule + wall)
Selected AbstractsPittosporum undulatum Vent. grown in Portugal: secretory structures, seasonal variation and enantiomeric composition of its essential oilFLAVOUR AND FRAGRANCE JOURNAL, Issue 1 2007Nicolau J. Ferreira Abstract Aerial parts of Pittosporum undulatum were collected fortnightly for 1 year at the Parque de Saúde de Lisboa. Collective samples of two populations were investigated, i.e. from pruned and non-pruned trees, and in addition samples from one pruned and one non-pruned individual. An SEM study of the aerial parts showed the presence of non-glandular T-shaped trichomes, and capitate trichomes with an elongated stalk and two to four round-shaped cells on the top. Numerous canals were seen at the level of the capsule wall as well as in the leaves and stems. Essential oil samples were isolated from the (deep-frozen) aerial parts by hydrodistillation to estimate the oil yields, and by distillation,extraction to determine their percentage composition, and analysed by GC and GC,MS. Monoterpenes (59,97%) were dominant in all oils, sabinene (5,58%), limonene (2,37%) and terpinen-4-ol (4,27%) being the major components, although in different relative amounts during the year of collection. Benzyl benzoate (8%) and benzyl salicylate (10%) attained high relative amounts in the oils from fully developed flowers, whereas in the oils from the other plant parts their relative amounts did not exceed 1%. The enantiomeric ratio of sabinene, limonene and terpinen-4-ol was investigated in the leaf, flower and capsule oils, showing dominance of the (+)-forms and homogeneity between all the oil samples. Copyright © 2006 John Wiley & Sons, Ltd. [source] Microgel-Based Engineered Nanostructures and Their Applicability with Template-Directed Layer-by-Layer Polyelectrolyte Assembly in Protein EncapsulationMACROMOLECULAR BIOSCIENCE, Issue 5 2005Dinesh B. Shenoy Abstract Summary: A novel strategy for the fabrication of microcapsules is elaborated by employing biomacromolecules and a dissolvable template. Calcium carbonate (CaCO3) microparticles were used as sacrificial templates for the two-step deposition of polyelectrolyte coatings by surface controlled precipitation (SCP) followed by the layer-by-layer (LbL) adsorption technique to form capsule shells. When sodium alginate was used for inner shell assembly, template decomposition with an acid resulted in simultaneous formation of microgel-like structures due to calcium ion-induced gelation. An extraction of the calcium after further LbL treatment resulted in microcapsules filled with the biopolymer. The hollow as well as the polymer-filled polyelectrolyte capsules were characterized using confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), and scanning force microscopy (SFM). The results demonstrated multiple functionalities of the CaCO3 core , as supporting template, porous core for increased polymer accommodation/immobilization, and as a source of shell-hardening material. The LbL treatment of the core-inner shell assembly resulted in further surface stabilization of the capsule wall and supplementation of a nanostructured diffusion barrier for encapsulated material. The polymer forming the inner shell governs the chemistry of the capsule interior and could be engineered to obtain a matrix for protein/drug encapsulation or immobilization. The outer shell could be used to precisely tune the properties of the capsule wall and exterior. Confocal laser scanning microscopy (CLSM) image of microcapsules (insert is after treating with rhodamine 6G to stain the capsule wall). [source] Encapsulation and Stabilization of Photo-Sensitive Antioxidants by Using Polymer Microcapsules with Controlled Phase HeterogeneityMACROMOLECULAR RAPID COMMUNICATIONS, Issue 6 2008Bo-Mi Koo Abstract We describe a robust method for both encapsulating and stabilizing photo-sensitive antioxidants in polymer microcapsules prepared by a water-in-oil-in-water double emulsification and evaporation technique, in which a volatile solvent from the oil layer consisting of poly(methyl methacrylate) and methylene chloride is gradually removed. Using poly(ethylene glycol) (PEG) in this study, we demonstrate that control over its molecular weight allows to tune the phase property of the capsule wall; introducing PEG with high molecular weight results in increased heterogeneity. The heterogeneity of the capsule walls displays an ability to effectively block sunlight, which is essential for improving the molecular stability of photo-sensitive antioxidants. In this study, we experimentally confirm this by observing natural sunlight-driven molecular decomposition of a model antioxidant, riboflavin-5,-phosphate, in poly (methyl methacrylate) microcapsules. [source] Poly(ethyleneimine) microcapsules: glutaraldehyde-mediated assembly and the influence of molecular weight on their propertiesPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 7 2008Weijun Tong Abstract Poly(ethyleneimine) (PEI) microcapsules were prepared via the method of glutaraldehyde (GA)-mediated covalent layer-by-layer (LbL) assembly, which utilized GA to cross-link the adsorbed PEI layer and to introduce free aldehyde group on the surface for the next PEI adsorption on MnCO3 microparticles, followed by core removal. Evidenced by ellipsometry, the PEI multilayers grew nearly linearly along with the layer number and their thickness was controlled at the nanometer scale. The hollow structure, morphology, and wall thickness were characterized by scanning electron microscopy (SEM), scanning force microscopy (SFM), and confocal laser scanning microscopy (CLSM), revealing that the capsule structure as well as the cut-off molecular weight of the capsule wall could be tuned by the molecular weight of PEI. This offers a general and novel pathway to fabricate single component capsules with pre-designed structure (size, shape, and wall thickness) and properties. Copyright © 2007 John Wiley & Sons, Ltd. [source] The latex capacity of opium poppy capsules is fixed early in capsule development and is not a major determinant in morphine yieldANNALS OF APPLIED BIOLOGY, Issue 2 2009T. Harvest Abstract This study found that the latex capacity (mg latex mg,1 dry weight capsule) of opium poppy capsules is fixed early in capsule development. Latex capacity, which represents the proportion of the capsule wall allocated to laticifers (specialised cells for latex storage), had peaked in the capsule at 1 week after flowering. In contrast, the morphine content of capsules continued to increase with capsule development until commercial harvest. Morphine content was correlated with capsule mass and total latex mass, but there was no correlation between latex capacity and morphine yield. The most important morphological characteristic in terms of morphine end yield (commercial harvest stage) was capsule mass. The findings of this study demonstrate that although latex yield per plant is a highly heritable morphological characteristic, it may have limited potential for use in a breeding strategy aimed at increasing the morphine yield from capsules. [source] Fabrication of Organized Porphyrin-Nanotube-Attached Heat-Sensitive Polyelectrolyte Capsules,ADVANCED FUNCTIONAL MATERIALS, Issue 16 2006S. Sadasivan Abstract A facile method of connecting fluorescent meso -tetrakis(4-sulfonatophenyl)porphine tetranion nanotubes to polyelectrolyte capsules is developed. Heat-sensitive robust polyelectrolyte capsules consisting of poly(diallyldimethylammonium chloride) and poly(styrene sulfonate) multilayers have been fabricated using the conventional layer-by-layer technique. Supramolecular aggregation of porphyrin monomers to nanotubes is induced in the microenvironment of the capsules by sequential addition of salt and acid. Scanning electron microscopy, transmission electron microscopy, and atomic force microscopy images reveal satellite-like structures consisting of a central capsule core with porphyrin nanotubes emerging radially from the capsule walls. The growth and the distribution of the porphyrin units have been monitored by UV-vis spectroscopy, fluorescence spectroscopy, and confocal laser scanning microscopy. Changing the temperature alters the dimensions and the arrangement of the nanotubes on the capsule walls. Such an attachment of porphyrin tubes onto robust functional capsules should help in developing an artificial light-harvesting system. [source] Micelles-Encapsulated Microcapsules for Sequential Loading of Hydrophobic and Water-Soluble DrugsMACROMOLECULAR RAPID COMMUNICATIONS, Issue 11 2010Weijun Tong Abstract Layer-by-layer (LbL) assembly was conducted on CaCO3 microparticles pre-doped with polystyrene- block -poly(acrylic acid) (PS- b -PAA) micelles, and resulted in micelles encapsulation in the microcapsules after core removal. Distribution of the micelles in the templates and capsules was characterized by transmission electron microscopy and confocal laser scanning microscopy. The micelles inside the capsules connected with each other to form a chain and network-like structure with a higher density near the capsule walls. The hydrophobic PS cores were then able to load small uncharged hydrophobic drugs while the negatively charged PAA corona could induce spontaneous deposition of water-soluble positively charged drugs such as doxorubicin. [source] Encapsulation and Stabilization of Photo-Sensitive Antioxidants by Using Polymer Microcapsules with Controlled Phase HeterogeneityMACROMOLECULAR RAPID COMMUNICATIONS, Issue 6 2008Bo-Mi Koo Abstract We describe a robust method for both encapsulating and stabilizing photo-sensitive antioxidants in polymer microcapsules prepared by a water-in-oil-in-water double emulsification and evaporation technique, in which a volatile solvent from the oil layer consisting of poly(methyl methacrylate) and methylene chloride is gradually removed. Using poly(ethylene glycol) (PEG) in this study, we demonstrate that control over its molecular weight allows to tune the phase property of the capsule wall; introducing PEG with high molecular weight results in increased heterogeneity. The heterogeneity of the capsule walls displays an ability to effectively block sunlight, which is essential for improving the molecular stability of photo-sensitive antioxidants. In this study, we experimentally confirm this by observing natural sunlight-driven molecular decomposition of a model antioxidant, riboflavin-5,-phosphate, in poly (methyl methacrylate) microcapsules. [source] Incorporation of Carbon Nanotubes into Hollow Microcapsules Using a Removable Template Assembly,MACROMOLECULAR RAPID COMMUNICATIONS, Issue 24 2004Qinghe Zhao Abstract Summary: Carboxylated multiwalled carbon nanotubes (MWNTs) were assembled with poly(allylamine hydrochloride) (PAH) onto decomposable colloidal particles, to subsequently yield hollow microcapsules after core removal. A sandwich structure with MWNTs layer embedded in poly(styrenesulfonate sodium salt) (PSS)/PAH multilayers was designed and constructed on melamine formaldehyde particles. Transmission electron microscopy and confocal microscopy revealed the hollow structure and good dispersity of the resultant microcapsules. The MWNTs were uniformly distributed on the capsule walls. TEM images of (PSS/PAH)5/MWNT/(PAH/PSS)2 microcapsules templated on MF microparticles, after core decomposition (main). They still preserve their continuous and intact structure with no signs of rupture. Inset: magnified surface. [source] Chiral Encapsulation by Directional InteractionsCHEMISTRY - A EUROPEAN JOURNAL, Issue 45 2009Agnieszka Szumna Abstract The complexation of chiral guests in the cavity of dimeric self-assembled chiral capsule 12 was studied by using NMR spectroscopy and X-ray crystallography. Capsule 12 has walls composed of amino acid backbones forming numerous directional binding sites that are arranged in a chiral manner. The polar character of the interior dictates the encapsulation preferences towards hydrophilic guests and the ability of the capsule to extract guests from water into an organic phase. Chiral discrimination towards hydroxy acids was evaluated by using association constants and competition experiments, and moderate de values were observed (up to 59,%). Complexes with one or two guest molecules in the cavity were formed. For 1:1 complexes, solvent molecules are coencapsulated; this influences guest dynamics and makes the chiral recognition solvent dependent. Reversal of the preferences can be induced by coencapsulation of a nonchiral solvent in the chiral internal environment. For complexes with two guests, filling of the capsule's internal space can be very effective and packing coefficients of up to 70,% can be reached. The X-ray crystal structure of complex 12,((S) -6)2 with well-resolved guest molecules reveals a recognition motif that is based on an extensive system of hydrogen bonds. The optimal arrangement of interactions with the alternating positively and negatively charged groups of the capsule's walls is fulfilled by the guest carboxylic groups acting simultaneously as hydrogen-bond donors and acceptors. An additional guest molecule interacting externally with the capsule reveals a possible entrance mechanism involving a polar gate. In solution, the structural features and dynamic behavior of the D4 -symmetric homochiral capsule were analyzed by variable-temperature NMR spectroscopy and the results were compared with those for the S8 -symmetric heterochiral capsule. [source] | |||||||||||||