title: Temperature-sensitive poly(N-(2-hydroxypropyl)methacrylamide mono/dilactate)-coated liposomes for triggered contents release.
abstract: We prepared thermosensitive poly( N-(2-hydroxypropyl)methacrylamide mono/dilactate) (pHPMA mono/dilactate) polymer and studied temperature-triggered contents release from polymer-coated liposomes. HPMA mono/dilactate polymer was synthesized with a cholesterol anchor suitable for incorporation in the liposomal bilayers and with a cloud point (CP) temperature of the polymer slightly above normal body temperature (42 degrees C). Dynamic light scattering (DLS) measurements showed that whereas the size of noncoated liposomes remained stable upon raising the temperature from 25 to 46 degrees C, polymer-coated liposomes aggregated around 43 degrees C. Also, noncoated liposomes loaded with calcein showed hardly any leakage of the fluorescent marker when heated to 46 degrees C. However, polymer-coated liposomes showed a high degree of temperature-triggered calcein release above the CP of the polymer. Likely, liposome aggregation and bilayer destabilization are triggered because of the precipitation of the thermosensitive polymer above its CP onto the liposomal bilayers, followed by permeabilization of the liposomal membrane. This study demonstrates that liposomes surface-modified with HPMA mono/dilactate copolymer are attractive systems for achieving temperature-triggered contents release.
authors.affiliation: Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Sorbonnelaan 16, 3584 CA, Utrecht, The Netherlands. Lauri.Paasonen@helsinki.fi
authors.forename: Lauri
authors.initials: L
authors.lastname: Paasonen
authors.forename: Birgit
authors.initials: B
authors.lastname: Romberg
authors.forename: Gert
authors.initials: G
authors.lastname: Storm
authors.forename: Marjo
authors.initials: M
authors.lastname: Yliperttula
authors.forename: Arto
authors.initials: A
authors.lastname: Urtti
authors.forename: Wim E
authors.initials: WE
authors.lastname: Hennink
mesh_terms: D000178:Acrylamides / Q000138:chemical synthesis / Q000737:chemistry*; D002784:Cholesterol / Q000737:chemistry; D005452:Fluoresceins; D007773:Lactates / Q000138:chemical synthesis / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D011109:Polymethacrylic Acids / Q000138:chemical synthesis / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013696:Temperature
chemical_list: D000178:Acrylamides; D005452:Fluoresceins; D007773:Lactates; D008081:Liposomes; D011109:Polymethacrylic Acids; C509680:poly(N-(2-hydroxypropyl) methacrylamide lactate); C525969:poly(N-(2-hydroxypropyl)methacrylamide dilactate); D002784:Cholesterol; C007740:fluorexon