title: Long-circulating poly(ethylene glycol)-poly(D,L-lactide) block copolymer micelles with modulated surface charge.
abstract: Reactive polymeric micelles consisting of an alpha-acetal-poly(ethylene glycol)-poly(D,L-lactide) block copolymer (acetal-PEG-PDLLA) with a narrow size distribution were prepared in this study to conjugate small peptidyl ligands, tyrosine (Tyr) and tyrosyl-glutamic acid (Tyr-Glu), through reductive amination after converting the alpha-acetal group to an aldehyde group, allowing modulation of the surface charge of the micelles from neutral (Tyr-) to anionic (Tyr-Glu-). Both of these micelles showed a significantly long circulating time in the blood compartment with 25% of injected dose still circulating even at 24 h. Further, an appreciably lowered uptake into the liver and spleen was demonstrated for the anionic Tyr-Glu-conjugated PEG-PDLLA micelle compared with a neutral Tyr-conjugated micelle, suggesting a substantial role of the slight anionic charge on the micelle surface in avoiding non-specific organ uptake. Stability of the micelle form in the blood compartment was directly observed for the Tyr-PEG-PDLLA micelle by a gel filtration assay of a plasma sample collected from the micelle-injected mice at 24 h. These results demonstrated that a surface-modulated PEG-PDLLA micelle with a suitable size and a narrowly distributed nature has promising potential as a long-circulating carrier system with desirable biocompatibility and biofunctionality.
authors.affiliation: Department of Materials Science, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Y
authors.initials: Y
authors.lastname: Nagasaki
authors.forename: Y
authors.initials: Y
authors.lastname: Kato
authors.forename: Y
authors.initials: Y
authors.lastname: Sugiyama
authors.forename: K
authors.initials: K
authors.lastname: Kataoka
mesh_terms: D004337:Drug Carriers; D008823:Micelles; D008970:Molecular Weight; D011091:Polyesters / Q000737:chemistry* / Q000493:pharmacokinetics; D011092:Polyethylene Glycols / Q000737:chemistry* / Q000493:pharmacokinetics; D014018:Tissue Distribution
chemical_list: D004337:Drug Carriers; D008823:Micelles; D011091:Polyesters; D011092:Polyethylene Glycols; C033616:poly(lactide)