title: A polymeric micelle MRI contrast agent with changeable relaxivity.
abstract: Polymeric micelles were formed from cationic polymers (polyallylamine or protamine) and anionic block copolymers (poly(ethylene glycol)-b-poly(aspartic acid) derivative) that bound Gd ions providing high contrasts in Magnetic Resonance Imaging (MRI) by shortening the T(1) longitudinal relaxation time of protons of water. The Gd-binding block copolymer alone showed high relaxivity (T(1)-shortening ability) values from 10 to 11 mol(-1) s(-1), while the polymeric micelles exhibited low relaxivity values from 2.1 to 3.6 mol(-1) s(-1). These findings point to the feasibility of a novel MRI contrast agent that selectively provides high contrasts at solid tumor sites owing to a dissociation of the micelle structures, while selective delivery to the tumor sites is achieved in the polymeric micelle form.
authors.affiliation: Tokyo University of Science, Department of Pharmaceutics, 2641 Yamasaki, Noda, Chiba 278-8510, Japan.
authors.forename: Emiko
authors.initials: E
authors.lastname: Nakamura
authors.forename: Kimiko
authors.initials: K
authors.lastname: Makino
authors.forename: Teruo
authors.initials: T
authors.lastname: Okano
authors.forename: Tatsuhiro
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Masayuki
authors.initials: M
authors.lastname: Yokoyama
mesh_terms: D003287:Contrast Media / Q000008:administration & dosage* / Q000737:chemistry; D019786:Gadolinium DTPA / Q000008:administration & dosage* / Q000737:chemistry; D008279:Magnetic Resonance Imaging; D008823:Micelles; D009369:Neoplasms / Q000175:diagnosis; D011108:Polymers / Q000008:administration & dosage*
chemical_list: D003287:Contrast Media; D008823:Micelles; D011108:Polymers; D019786:Gadolinium DTPA