title: Preparation of poly(L-lactide)-based microspheres having a cationic or anionic surface using biodegradable surfactants.
abstract: Poly(L-lactide)-based microspheres having cationic or anionic surfaces were prepared using polydepsipeptide-block-poly(L-lactide)s as surfactants. Polydepsipeptide-block-poly(L-lactide)s having amino or carboxylic acid groups on their side chains were synthesized through anionic ring-opening polymerizations of L-lactide using the corresponding protected polydepsipeptides as macroinitiators and consequent deprotections. Since these amphiphilic copolymers consisting of hydrophobic segments and hydrophilic segments with amino or carboxylic acid groups could be converted to cationic or anionic block copolymers, they could act as surfactants preparing poly(L-lactide)-based microspheres by an oil-in-water emulsion method. The amount of ionic groups located on the surfaces of the obtained microspheres was found to increase with increasing the feed of charged polydepsipeptide-block-poly(L-lactide)s in the blend of poly(L-lactide) and block copolymers. The average diameters of the dried microspheres estimated by scanning electron microscopy were found to decrease with an increase in feed of block copolymers in polymer blends.
authors.affiliation: Faculty of Engineering & High Technology Research Center, Kansai University, Suita, Osaka 564-8680, Japan.
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Ouchi
authors.forename: Megumi
authors.initials: M
authors.lastname: Toyohara
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Arimura
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Ohya
mesh_terms: D000838:Anions; D001673:Biodegradation, Environmental; D002412:Cations; D008863:Microspheres; D011091:Polyesters / Q000138:chemical synthesis* / Q000737:chemistry; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D000838:Anions; D002412:Cations; D011091:Polyesters; D013501:Surface-Active Agents; C033616:poly(lactide)