title: Self-assembled thermo- and pH responsive micelles of poly(10-undecenoic acid-b-N-isopropylacrylamide) for drug delivery.
abstract: An amphiphilic AB block copolymer composed of poly(N-isopropylacrylamide) as a hydrophilic segment and poly(10-undecenoic acid) as a hydrophobic segment was synthesized. Cytotoxicity study of this copolymer exhibited no significant cytotoxicity. The lower critical solution temperature (LCST) of the copolymer was 30.8 degrees C, as determined by the turbidity method. The block copolymer forms micelles in an aqueous medium at the temperature lower than the LCST. Transmission electron microscopy images showed that these micelles were regularly spherical in shape. The micelle size determined by size analysis was around 160 nm. The anti-inflammation drug prednisone acetate was incorporated into the micelles and the release profiles of prednisone acetate showed a dramatic thermoresponsive switching behavior and a unique pH responsive behavior. Moreover, the pH responsive behavior was in relation to the thermoresponsive behavior. That is, the micelles were not pH sensitive at the temperature below the LCST, but the aggregates were pH sensitive at the temperature above the LCST. Based on these results, the thermo- and pH responsive micelles have great potential to be a novel carrier for drug delivery.
authors.affiliation: Department of Chemistry and Key Laboratory of Biomedical Polymers of Ministry of Education, Wuhan University, Wuhan 430072, P. R. China.
authors.forename: Hua
authors.initials: H
authors.lastname: Wei
authors.forename: Xian-Zheng
authors.initials: XZ
authors.lastname: Zhang
authors.forename: Han
authors.initials: H
authors.lastname: Cheng
authors.forename: Wen-Qin
authors.initials: WQ
authors.lastname: Chen
authors.forename: Si-Xue
authors.initials: SX
authors.lastname: Cheng
authors.forename: Ren-Xi
authors.initials: RX
authors.lastname: Zhuo
mesh_terms: D000180:Acrylic Resins / Q000009:adverse effects / Q000138:chemical synthesis* / Q000737:chemistry; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004337:Drug Carriers / Q000009:adverse effects / Q000138:chemical synthesis* / Q000737:chemistry; D004355:Drug Stability; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008823:Micelles; D046529:Microscopy, Electron, Transmission; D015394:Molecular Structure; D008970:Molecular Weight; D053758:Nanoparticles; D010316:Particle Size; D011241:Prednisone / Q000008:administration & dosage / Q000737:chemistry; D012995:Solubility; D013499:Surface Properties; D013696:Temperature
chemical_list: D000180:Acrylic Resins; D004337:Drug Carriers; D008823:Micelles; C517625:poly(10-undecenoic acid-b-N-isopropylacrylamide); D011241:Prednisone