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Int J Pharm. 2014 Dec 10;476(1-2):31-40. doi: 10.1016/j.ijpharm.2014.09.029. Epub 2014 Sep 24.

Thermo-responsive release of curcumin from micelles prepared by self-assembly of amphiphilic P(NIPAAm-co-DMAAm)-b-PLLA-b-P(NIPAAm-co-DMAAm) triblock copolymers.

Author information

1
Institut des Biomolécules Max Mousseron, UMR CNRS 5247 - Equipe Biopolymères Artificiels, Université Montpellier I, 15 Avenue Charles Flahault, BP 14491, 34093 Montpellier Cedex 5, France.
2
Institut Charles Gerhardt, UMR 5253CNRS-UM2-ENSCM-UM1 - Equipe Ingénierie et Architectures Macromoléculaires, Université Montpellier II, cc1702, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France.
3
Institut des Biomolécules Max Mousseron, UMR CNRS 5247 - Equipe Biopolymères Artificiels, Université Montpellier I, 15 Avenue Charles Flahault, BP 14491, 34093 Montpellier Cedex 5, France; Institut Europeen des Membranes, UMR CNRS 5635, University of Montpellier 2, 34095 Montpellier, France. Electronic address: lisuming@univ-montp1.fr.
4
College of Chemical Engineering, Qingdao University of Science and Technology, 266042 Qingdao, China.

Abstract

Thermo-responsive micelles are prepared by self-assembly of amphiphilic triblock copolymers composed of a poly(l-lactide) (PLLA) central block and two poly(N-isopropylacrylamide-co-N,N-dimethylacrylamide) (P(NIPAAm-co-DMAAm)) lateral blocks, using solvent evaporation/film hydration method. The resulting micelles exhibit very low critical micelle concentration (CMC) which slightly increases from 0.0113 to 0.0144 mg mL(-1) while the DMAAm content increases from 31.8 to 39.4% in the hydrophilic P(NIPAAm-co-DMAAm) blocks. The lower critical solution temperatures (LCST) of copolymers varies from 44.7 °C to 49.4 °C in water as determined by UV spectroscopy, and decreases by ca. 3.5 °C in phosphate buffered saline (PBS). Curcumin was encapsulated in the core of micelles. High drug loading up to 20% is obtained with high loading efficiency (>94%). The LCST of drug loaded micelles ranges from 37.5 to 38.0 °C with drug loading increasing from 6.0 to 20%. The micelles with diameters ranging from 47.5 to 88.2 nm remain stable over one month due to the negative surface charge as determined by zeta potential (-12.4 to -18.7 mV). Drug release studies were performed under in vitro conditions at 37 °C and 40 °C, i.e. below and above the LCST, respectively. Initial burst release is observed in all cases, followed by a slower release. The release rate is higher at 40 °C than that at 37 °C due to thermo-responsive release across the LCST. On the other hand, micelles with lower drug loading exhibit higher release rate than those with higher drug loading, which is assigned to the solubility effect. Peppas' theory was applied to describe the release behaviors. Moreover, the in vitro cytotoxicity of copolymers was evaluated using MTT assay. The results show that the copolymers present good cytocompatibility. Therefore, the nano-scale size, low CMC, high drug loading and stability, as well as good biocompatibility indicate that these thermo-responsive triblock copolymer micelles present a good potential as carrier for targeted delivery of anticancer drugs.

KEYWORDS:

Curcumin; Micelle; Poly(N-isopropylacrylamide); Poly(l-lactide); Self-assembly; Thermo-responsive

PMID:
25260217
DOI:
10.1016/j.ijpharm.2014.09.029
[Indexed for MEDLINE]

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