Block copolymer micelles for drug delivery: design, characterization and biological significance

Recently, colloidal carrier systems have been receiving much attention in t he field of drug targeting because of their high loading capacity for drugs as well as their unique disposition characteristics in the body. This pape r highlights the utility of polymeric micelles formed through the multimole cular assembly of block copolymers as novel core-shell typed colloidal carr iers for drug and gene targeting. The process of micellization in aqueous m ilieu is described in detail based on differences in the driving force of c ore segregation, including hydrophobic interaction, electrostatic interacti on. metal complexation, and hydrogen bonding of constituent block copolymer s. The segregated core embedded in the hydrophilic palisade is shown to fun ction as a reservoir for gents, enzymes, and a variety of drugs with divers e characteristics. Functionalization of the outer surface of the polymeric micelle to modify its physicochemical and biological properties is reviewed from the standpoint of designing micellar carrier systems for receptor-med iated drug delivery. Further. the distribution of polymeric micelles is des cribed to demonstrate their long-circulating characteristics and significan t tumor accumulation. emphasizing their promising utility in tumor-targetin g therapy. As an important perspective on carrier systems based on polymeri c micelles, their feasibility as non-viral gene vectors is also summarized in this review article. (C) 2001 Elsevier Science B.V. All rights reserved.