title: Phase transfer and characterization of poly(epsilon-caprolactone) and poly(L-lactide) microspheres.
abstract: A method suitable for transfer of poly(epsilon-caprolactone) and poly(L-lactide) microspheres (synthesized by pseudoanionic dispersion polymerization of epsilon-caprolactone and L-lactide in heptane-1,4-dioxane mixed solvent) from heptane to water was developed. This method consists of treating the microspheres with KOH-ethanol in the presence of surfactants (nonionic Triton X-405, anionic sodium dodecyl sulfate (SDS), and zwitterionic ammonium sulfobetaine-2 (ASB)). Partial hydrolysis of polyesters results in the formation of hydroxyl and carboxyl groups in the surface layer of microspheres and enhances their stability in water-based media. Minimal concentrations of surfactants, needed to obtain stable suspensions of particles, were equal to 3 x 10(-2) and 6 x 10(-2), and 3 x 10(-2) mol l(-1) for Triton X-405. SDS, and ASB, respectively. In the case of poly(epsilon-caprolactone) microspheres, suspensions in water were stable for all three surfactants for pH values ranging from 3 to 11. Suspensions of poly(L-lactide) were stable in the same range of pH values only for ASB. Surface charge density determined by electrophoretic mobility varied for poly(epsilon-caprolactone) microspheres from 2.6 x 10(-7) to 8.9 x 10(-7) mol m(-2), for particles stabilized with Triton X-405 and ASB. respectively. In the case of poly(L-lactide) microspheres, surface charge density varied from 3.9 x 10(-7) (stabilizer: Triton X-405) to 7.4 x 10(-7) mol m(-2) (stabilizer: ASB). Carboxyl groups located in the surface layer of poly(L-lactide) microspheres were used for covalent immobilization of 6-aminoquinoline, a fluorophore with an amino group. Maximum surface concentration of immobilized 6-aminoquinoline was equal to 1.9 x 10(-6) mol m(-2). Poly(epsilon-caprolactone) microspheres transferred into water were loaded with ethyl salicylate. Loading up to 38% (w/w) was obtained.
authors.affiliation: Center of Molecular and Macromolecular Studies, Polish Academy of Sciences, Lodz.
authors.forename: M
authors.initials: M
authors.lastname: Gadzinowski
authors.forename: S
authors.initials: S
authors.lastname: Slomkowski
authors.forename: A
authors.initials: A
authors.lastname: Elaïssari
authors.forename: C
authors.initials: C
authors.lastname: Pichot
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D010316:Particle Size; D011091:Polyesters / Q000737:chemistry*; D013501:Surface-Active Agents
chemical_list: D001672:Biocompatible Materials; D011091:Polyesters; D013501:Surface-Active Agents; C016240:polycaprolactone; C033616:poly(lactide)