title: Doxorubicin-loaded poly(ethylene glycol)-poly(beta-benzyl-L-aspartate) copolymer micelles: their pharmaceutical characteristics and biological significance.
abstract: Doxorubicin (DOX) was physically loaded into micelles prepared from poly(ethylene glycol)-poly(beta-benzyl-L-aspartate) block copolymer (PEG-PBLA) by an o/w emulsion method with a substantial drug loading level (15 to 20 w/w%). DOX-loaded micelles were narrowly distributed in size with diameters of approximately 50-70 nm. Dimer derivatives of DOX as well as DOX itself were revealed to be entrapped in the micelle, the former seems to improve micelle stability due to its low water solubility and possible interaction with benzyl residues of PBLA segments through pi-pi stacking. Release of DOX compounds from the micelles proceeded in two stages: an initial rapid release was followed by a stage of slow and long-lasting release of DOX. Acceleration of DOX release can be obtained by lowering the surrounding pH from 7.4 to 5.0, suggesting a pH-sensitive release of DOX from the micelles. A remarkable improvement in blood circulation of DOX was achieved by use of PEG-PBLA micelle as a carrier presumably due to the reduced reticuloendothelial system uptake of the micelles through a steric stabilization mechanism. Finally, DOX loaded in the micelle showed a considerably higher antitumor activity compared to free DOX against mouse C26 tumor by i.v. injection, indicating a promising feature for PEG-PBLA micelle as a long-circulating carrier system useful in modulated drug delivery.
authors.affiliation: Department of Materials Science, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Kataoka
authors.forename: T
authors.initials: T
authors.lastname: Matsumoto
authors.forename: M
authors.initials: M
authors.lastname: Yokoyama
authors.forename: T
authors.initials: T
authors.lastname: Okano
authors.forename: Y
authors.initials: Y
authors.lastname: Sakurai
authors.forename: S
authors.initials: S
authors.lastname: Fukushima
authors.forename: K
authors.initials: K
authors.lastname: Okamoto
authors.forename: G S
authors.initials: GS
authors.lastname: Kwon
mesh_terms: D018195:Adenosarcoma / Q000188:drug therapy*; D000818:Animals; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D003110:Colonic Neoplasms / Q000188:drug therapy*; D004317:Doxorubicin / Q000097:blood / Q000737:chemistry / Q000627:therapeutic use*; D004337:Drug Carriers / Q000493:pharmacokinetics; D016503:Drug Delivery Systems / Q000379:methods; D004355:Drug Stability; D004655:Emulsions; D006863:Hydrogen-Ion Concentration; D008297:Male; D051379:Mice; D008823:Micelles; D012157:Mononuclear Phagocyte System / Q000378:metabolism*; D010316:Particle Size; D010455:Peptides / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D012995:Solubility; D013997:Time Factors; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D004337:Drug Carriers; D004655:Emulsions; D008823:Micelles; D010455:Peptides; C033141:poly-beta-benzyl-aspartate; D011092:Polyethylene Glycols; D004317:Doxorubicin