title: Molecular design of biodegradable polymeric micelles for temperature-responsive drug release.
abstract: We designed thermo-responsive and biodegradable polymeric micelles for an ideal drug delivery system whose target sites are where external stimuli selectively release drugs from the polymeric micelles. The thermo-responsive micelles formed from block copolymers that were composed both of a hydrophobic block and a thermo-responsive block. Poly(N-isopropylacrylamide-co-N,N-dimethylacrylamide) showing a lower critical solution temperature (LCST) around 40 degrees C was synthesized for the thermo-responsive block, while biodegradable poly(D,L-lactide), poly(epsilon-caprolactone), or poly(D,L-lactide-co-epsilon-caprolactone) was used for the hydrophobic block. By changing both the block lengths of the poly(D,L-lactide)-containing block copolymers, physical parameters such as micelle diameter and critical micelle concentration were varied. On the other hand, the choice of the hydrophobic block was revealed to be critical in relation to both on the thermo-responsive release of the incorporated anti-cancer drug, doxorubicin, and the temperature-dependent change of the hydrophobicity of the micelles' inner core. One polymeric micelle composition successfully exhibited rapid and thermo-responsive drug release while possessing a biodegradable character.
authors.affiliation: Tokyo Women's Medical University, Institute of Advanced Biomedical Engineering and Science, Kawada-cho 8-1, Shinjuku-ku, Tokyo 162-8666, Japan.
authors.forename: Masamichi
authors.initials: M
authors.lastname: Nakayama
authors.forename: Teruo
authors.initials: T
authors.lastname: Okano
authors.forename: Takanari
authors.initials: T
authors.lastname: Miyazaki
authors.forename: Fukashi
authors.initials: F
authors.lastname: Kohori
authors.forename: Kiyotaka
authors.initials: K
authors.lastname: Sakai
authors.forename: Masayuki
authors.initials: M
authors.lastname: Yokoyama
mesh_terms: D000903:Antibiotics, Antineoplastic / Q000008:administration & dosage / Q000737:chemistry; D001711:Biotransformation; D003692:Delayed-Action Preparations; D004317:Doxorubicin / Q000008:administration & dosage / Q000737:chemistry; D015195:Drug Design; D007202:Indicators and Reagents; D008027:Light; D008823:Micelles; D017551:Microdialysis; D008970:Molecular Weight; D010316:Particle Size; D011091:Polyesters; D011108:Polymers; D012542:Scattering, Radiation; D013050:Spectrometry, Fluorescence; D013329:Structure-Activity Relationship; D013696:Temperature; D014462:Ultrafiltration
chemical_list: D000903:Antibiotics, Antineoplastic; D003692:Delayed-Action Preparations; D007202:Indicators and Reagents; D008823:Micelles; D011091:Polyesters; D011108:Polymers; C016240:polycaprolactone; C033616:poly(lactide); D004317:Doxorubicin