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Matrix-core/shell Microcapsules (shell + microcapsule)

Distribution by Scientific Domains
Polymers and Materials Science33%

Selected Abstracts

Progress technology in microencapsulation methods for cell therapy

BIOTECHNOLOGY PROGRESS, Issue 4 2009
Jean-Michel Rabanel
Abstract Cell encapsulation in microcapsules allows the in situ delivery of secreted proteins to treat different pathological conditions. Spherical microcapsules offer optimal surface-to-volume ratio for protein and nutrient diffusion, and thus, cell viability. This technology permits cell survival along with protein secretion activity upon appropriate host stimuli without the deleterious effects of immunosuppressant drugs. Microcapsules can be classified in 3 categories: matrix-core/shell microcapsules, liquid-core/shell microcapsules, and cells-core/shell microcapsules (or conformal coating). Many preparation techniques using natural or synthetic polymers as well as inorganic compounds have been reported. Matrix-core/shell microcapsules in which cells are hydrogel-embedded, exemplified by alginates capsule, is by far the most studied method. Numerous refinement of the technique have been proposed over the years such as better material characterization and purification, improvements in microbead generation methods, and new microbeads coating techniques. Other approaches, based on liquid-core capsules showed improved protein production and increased cell survival. But aside those more traditional techniques, new techniques are emerging in response to shortcomings of existing methods. More recently, direct cell aggregate coating have been proposed to minimize membrane thickness and implants size. Microcapsule performances are largely dictated by the physicochemical properties of the materials and the preparation techniques employed. Despite numerous promising pre-clinical results, at the present time each methods proposed need further improvements before reaching the clinical phase. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source]

Ultrabubble: A Laminated Ultrasound Contrast Agent with Narrow Size Range

ADVANCED MATERIALS, Issue 38-39 2009
Pei-Lun Lin
A laminated shell microcapsule is described resisting aggregation and withstanding ultrasound destruction, showing a good backscatter signal, as shown in the figure. Templated synthesis produces versatile monodisperse capsules <3 µm, with ultrasound-pressure dependency allowing rupture above MI , 1.5 (at 2 MHz), suitable for future development as both controlled-delivery agent and contrast agent. [source]

Restoration of Conductivity with TTF-TCNQ Charge-Transfer Salts

ADVANCED FUNCTIONAL MATERIALS, Issue 11 2010
Susan A. Odom
Abstract The formation of the conductive TTF-TCNQ (tetrathiafulvalene,tetracyanoquinodimethane) charge-transfer salt via rupture of microencapsulated solutions of its individual components is reported. Solutions of TTF and TCNQ in various solvents are separately incorporated into poly(urea-formaldehyde) core,shell microcapsules. Rupture of a mixture of TTF-containing microcapsules and TCNQ-containing microcapsules results in the formation of the crystalline salt, as verified by FTIR spectroscopy and powder X-ray diffraction. Preliminary measurements demonstrate the partial restoration of conductivity of severed gold electrodes in the presence of TTF-TCNQ derived in situ. This is the first microcapsule system for the restoration of conductivity in mechanically damaged electronic devices in which the repairing agent is not conductive until its release. [source]