Preparation and characterization of magnetic PLA-PEG composite particles

A series of biodegradable block copolymers of poly-D,L-lactide-co-polyethylene glycol (PLA-PEG) were prepared out by ring-opening polymerization of D,L-lactide with stannous caprylate (Sn(Oct)(2)) as catalyst, then the PLA-PEG copolymers and magnetic Fe3O4 were made into composite particles by phase separation method. The sizes and distribution of composite particles were investigated by laser particle size analyzer. The morphologies of the prepared particles were examined by TEM. The contents of Fe in composite particles were detected by ICP. The magnetic susceptibilities were measured by nephelometery and VSM. The particles prepared were spherical with a size range of 100-200 nm. The sizes of the particles were influenced by PEG molecular weights and block ratio. The magnetic properties of composite particles increased with the increase of PEG molecular weights and block ratio. The properties of magnetic composite particles were controlled by altering the block ratio and the molecular weight of PLA-PEG copolymer. The prepared Fe3O4/PLA-PEG particles with magnetic properties and biodegradable properties would provide useful applications in drug targeting and drug controlling release. (c) 2005 Elsevier B.V. All rights reserved.