Core Removal (core + removal)

Distribution by Scientific Domains


Selected Abstracts


Contact-Killing Polyelectrolyte Microcapsules Based on Chitosan Derivatives

ADVANCED FUNCTIONAL MATERIALS, Issue 19 2010
Di Cui
Abstract Polyelectrolyte-multilayer microcapsules are made by layer-by-layer (LbL) assembly of oppositely charged polyelectrolytes onto sacrificial colloidal particles, followed by core removal. In this paper, contact-killing polyelectrolyte microcapsules are prepared based solely on polysaccharides. To this end, water-soluble quaternized chitosan (QCHI) with varying degrees of substitution (DS) and hyaluronic acid (HA) are assembled into thin films. The quaternary ammonium groups are selectively grafted on the primary amine group of chitosan by exploiting its reaction with glycidyltrimethylammonium chloride (GTMAC) under homogeneous aqueous acidic conditions. The morphology of the capsules is closely dependent on the DS of the quaternized chitosan derivatives, which suggests differences in their complexation with HA. The DS is also a key parameter to control the antibacterial activity of QCHI against Escherichia Coli (E. coli). Thus, capsules containing the QCHI derivative with the highest DS are shown to be the most efficient to kill E. coli while retaining their biocompatibility toward myoblast cells, which suggests their potential as drug carriers able to combat bacterial infections. [source]


In Situ Coacervated Microcapsules with Filled Polyelectrolytes and Charge-Controlled Permeation for Dye Molecules

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 9 2008
Feng Wang
Abstract Microcapsules with charge-controlled permeation for electrolytes were fabricated by an in situ coacervation method in the presence of polyelectrolyte during core removal. A layer of PAH was adsorbed onto PSS-doped CaCO3 microparticles, followed by crosslinking of the PAH layer with GA and core removal in a solution of EDTA with or without PAH. In the presence of PAH, microcapsules with a larger size, weight and PSS content than with PAH were obtained. Microcapsules produces without PAH showed a unique feature of charge-controlled permeation for electrolytes: negatively charged probes were completely rejected, but positively charged ones were attracted. [source]


Micelles-Encapsulated Microcapsules for Sequential Loading of Hydrophobic and Water-Soluble Drugs

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 11 2010
Weijun 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]


Incorporation of Carbon Nanotubes into Hollow Microcapsules Using a Removable Template Assembly,

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 24 2004
Qinghe 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]


Poly(ethyleneimine) microcapsules: glutaraldehyde-mediated assembly and the influence of molecular weight on their properties

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 7 2008
Weijun 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]