Premium
Self‐assembled thermosensitive micelles based on poly( L ‐lactide‐star block‐ N ‐isopropylacrylamide) for drug delivery
Author(s) -
Wei Hua,
Zhang XianZheng,
Chen WenQin,
Cheng SiXue,
Zhuo RenXi
Publication year - 2007
Publication title -
journal of biomedical materials research part a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.849
H-Index - 150
eISSN - 1552-4965
pISSN - 1549-3296
DOI - 10.1002/jbm.a.31295
Subject(s) - micelle , poly(n isopropylacrylamide) , materials science , copolymer , lower critical solution temperature , drug delivery , amphiphile , lactide , chemical engineering , polymer chemistry , polymer , aqueous solution , nanotechnology , organic chemistry , chemistry , composite material , engineering
A novel seven‐arm star block copolymer poly( L ‐lactide‐ star block ‐ N ‐isopropylacrylamide) (PLLA‐ sb ‐PNIPAAm), comprised of a hydrophobic poly( L ‐lactide) (PLLA) arm and an average of six hydrophilic poly( N ‐isopropylacrylamide) (PNIPAAm) arms, was designed and synthesized. The amphiphilic PLLA‐ sb ‐PNIPAAm copolymer was capable of self‐assembling into nano‐sized micelle in water, which was confirmed by FT‐IR, 1 H NMR and fluorescence spectroscopy. Transmission electron microscopy images showed that these nano‐sized micelles were regularly spherical in shape. Micelle size determined by size analysis was around 100 nm in diameter. The micelles showed reversible dispersion/aggregation in response to temperature changes through an outer polymer shell of PNIPAAm at around 31°C, observed by optical absorbance measurements. The anticancer drug methotrexate (MTX) as model drug was loaded in the polymeric nano‐sized micelles. In vitro release behavior of MTX was investigated, which showed a drastic 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. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007