title: A free-standing, sheet-shaped, "hydrophobic" biomaterial containing polymeric micelles formed from poly(ethylene glycol)-poly(lactic acid) block copolymer for possible incorporation/release of "hydrophilic" compounds.
abstract: Sheet-shaped materials with a large contact area relative to the drug targeting site lead to advantages over conventional particle-shaped drug carriers and have several advantages for their biomedical applications. The present study proposes a methodology for preparing a novel sheet-shaped "hydrophobic" and biocompatible biomaterial in which polymeric micelles are uniformly dispersed for the incorporation of "hydrophilic" compounds into the sheet. The methoxy-terminated poly(ethylene glycol)-block-poly(lactic acid) block copolymer (CH(3)O-PEG-b-PLA) was successfully synthesized by means of the anionic ring-opening polymerization of both ethylene oxide and dl-lactide. CH(3)O-PEG-b-PLA was self-assembled and formed stable micelle-like w/o emulsion with a hydrophilic inner core in organic solvents. A sheet-shaped material containing a hydrophilic inner space for incorporating hydrophilic compounds was obtained by spin-coating both the micelle solution and a sheet-forming polymer. Fluorescent images of the sheet proved that polymeric micelles providing hydrophilic spaces were uniformly dispersed in the hydrophobic sheet. The facile technique presented in this paper can be a tool for fabricating sheet-shaped biomaterials that have a hydrophilic inner core and, consequently, that are suitable for the sustained release of hydrophilic compounds.
authors.affiliation: Department of Organic and Polymer Materials Chemistry, Faculty of Engineering, Tokyo University of Agriculture and Technology, Tokyo 184-8588, Japan.
authors.forename: Hitomi
authors.initials: H
authors.lastname: Moroishi
authors.forename: Chikara
authors.initials: C
authors.lastname: Yoshida
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Murakami
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D004337:Drug Carriers / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D007773:Lactates / Q000737:chemistry; D008823:Micelles; D015394:Molecular Structure; D011092:Polyethylene Glycols / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*
chemical_list: D001672:Biocompatible Materials; D004337:Drug Carriers; D007773:Lactates; D008823:Micelles; D011108:Polymers; C088513:poly(lactic acid-ethylene glycol); D011092:Polyethylene Glycols