title: Self-assembled thermoresponsive micelles of poly(N-isopropylacrylamide-b-methyl methacrylate).
abstract: To achieve a combination of spatial specificity in a passive manner with a stimuli-response targeting mechanism, a temperature-responsive polymeric micelle was prepared using block copolymers of poly(N-isopropylacrylamide-b-methyl methacrylate) (PNIPAAm-b-PMMA). The critical micelle concentration of amphiphilic block copolymers in aqueous solution was determined by fluorescence spectroscopy using pyrene as a fluorescence probe. Transmission electron microscopy images showed that these nanoparticles were regularly spherical in shape. Micelle size determined by size analysis was around 190 nm. The micelles showed reversible dispersion/aggregation in response to temperature cycles through an outer polymer shell lower critical solution temperature (LCST) for PNIPAAm at around 33 degrees C, observed by optical absorbance measurements and dynamic light scattering (DLS). The anti-inflammation drug prednisone acetate was loaded as the model drug in the polymeric nanoparticles. In vitro release behavior of prednisone acetate was investigated, which showed a dramatic thermoresponsive fast/slow switching behavior according to the temperature-responsive structural changes of a micellar shell structure. The reversible and sensitive thermoresponse of this micelle might provide opportunities to construct a novel drug delivery system in conjunction with localized hyperthermia.
authors.affiliation: Key Laboratory of Biomedical Polymers of Ministry of Education, Department of Chemistry, Wuhan University, Wuhan 430072, PR China.
authors.forename: Hua
authors.initials: H
authors.lastname: Wei
authors.forename: Xian-Zheng
authors.initials: XZ
authors.lastname: Zhang
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhou
authors.forename: Si-Xue
authors.initials: SX
authors.lastname: Cheng
authors.forename: Ren-Xi
authors.initials: RX
authors.lastname: Zhuo
mesh_terms: D000178:Acrylamides / Q000138:chemical synthesis / Q000737:chemistry*; D000893:Anti-Inflammatory Agents / Q000737:chemistry; D016503:Drug Delivery Systems; D006358:Hot Temperature; D008689:Methacrylates / Q000138:chemical synthesis / Q000737:chemistry*; D008823:Micelles; D046529:Microscopy, Electron, Transmission; D049329:Nanostructures; D010316:Particle Size; D011241:Prednisone / Q000737:chemistry
chemical_list: D000178:Acrylamides; D000893:Anti-Inflammatory Agents; D008689:Methacrylates; D008823:Micelles; C509363:poly(N-isopropylacrylamide-b-methyl methacrylate); D011241:Prednisone