Physicochemical aspects of drug delivery and release from polymer-based colloids

Recent advances in the preparation/loading, surface properties, and applica tions of polymer-based colloidal drug delivery and release systems, such as block copolymer micelles, polymer nano- and microparticles, polymer-modifi ed liposomes, and chemical and physical hydrogels are presented. Drug relea se from polymer-based systems is affected by the drug-polymer interactions as well as the polymer microstructure and dissociation/erosion properties. Surface modification with poly(ethylene oxide) has become common in improvi ng the biocompatibility and biodistribution of drug delivery carriers. Site -specific drug delivery can be achieved by polymer-based colloidal drug car riers when Ligands of targeting information are attached on the carrier sur face or when a phase transition is induced by an external stimulus. While s ignificant progress in being made, many challenges remain in preserving the biological activity and attaining the desired drug release properties, esp ecially for protein and DNA drugs. (C) 2000 Elsevier Science Ltd. All right s reserved.