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Thermally responsive polymeric micelles self‐assembled by amphiphilic polyphosphazene with poly( N ‐isopropylacrylamide) and ethyl glycinate as side groups: Polymer synthesis, characterization, and in vitro drug release study
Author(s) -
Zhang Jian Xiang,
Qiu Li Yan,
Jin Yi,
Zhu Kang Jie
Publication year - 2005
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.30604
Subject(s) - polyphosphazene , lower critical solution temperature , poly(n isopropylacrylamide) , micelle , materials science , critical micelle concentration , polymer chemistry , aqueous solution , polymer , dynamic light scattering , amphiphile , nanocarriers , nanogel , nuclear chemistry , copolymer , drug delivery , chemical engineering , organic chemistry , nanoparticle , chemistry , nanotechnology , engineering , composite material
Abstract Thermally responsive amphiphilic poly( N ‐isopropylacrylamide) (PNIPAm)‐grafted‐polyphosphazene (PNIPAm‐ g ‐PPP) was synthesized by stepwise cosubstitution of chlorine atoms on polymer backbones with amino‐terminated NIPAm oligomers and ethyl glycinate (GlyEt). Polymer structure was confirmed by FT‐IR, 1 H NMR, elemental analysis, and GPC. The thermosensitivity of PNIPAm‐ g ‐PPP aqueous solution was investigated by turbidity method. The lower critical solution temperature (LCST) of PNIPAm‐ g ‐PPP was observed to be ∼30°C in water, while it was 24°C in 0.1 M PBS (pH 7.4). Micellization behavior of PNIPAm‐ g ‐PPP in aqueous solution was characterized by fluorescence probe technique, TEM, and DLS. The critical micelle concentration (CMC), thus, determined was 0.0187 g/L. Both TEM and DLS measurement suggested that the diameter of micelles was ∼190 nm at 20°C. Diflunisal (DIF)‐loaded micelles were prepared by dialysis method. In vitro release test at various temperatures was also performed to study the effect of temperature on the drug release profiles. It was demonstrated that DIF release from PNIPAm‐ g ‐PPP micelles was slower at the temperature of 37°C than that at 4°C. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006