Supramolecular self-assembly and controllable drug release of thermosensitive hyperbranched multiarm copolymers
writer：Guo, B.; Sun X.Y.; Zhou, Y. F.*; Yan, D. Y.*
keywords：hyperbranched polymers,thermosensitive copolymer,supramolecular,self-assembly,ATRP,drug delivery
source：期刊
specific source：Sci. China Ser. B-Chem. 2010, 53, 487. http://link.springer.com/article/10.1007/s11426-010-0083-2
Issue time：2010年
A novel temperature-responsive hyperbranched multiarm copolymer with a
hydrophobic hyperbranched poly(3-ethyl-3-(hydroxymethyl) oxetane) (HBPO)
core and thermosensitive poly(
N-isopropylacrylamide) (PNIPAM) arms was synthesized via the atom transfer radical polymerization (
ATRP)
of NIPAM monomers from a hyperbranched HBPO macroinitiator. It was
found that HBPO-star-PNIPAM self-assembled into multimolecular micelles
(around 60 nm) in water at room temperature according to pyrene probe
fluorescence spectrometry,
1H NMR, TEM,
and DLS measurements. The micelle solution showed a reversible
thermosensitive phase transition at a lower critical solution
temperature (LCST) (around 32°C) observed by variable temperature
optical absorbance measurements. Variable temperature NMR and DLS
analyses demonstrated that the LCST transition originated from the
secondary aggregation of the micelles driven by increasing hydrophobic
interaction due to the dehydration of PNIPAM shells upon heating. The
drug loading and release properties of HBPO-star-PNIPAM micelles were
also investigated using prednisone acetate as a model drug. The micelles
showed a much improved drug encapsulation efficiency and
temperature-dependent sustainable release behavior due to the special
micellar structure. The micelles exhibited no apparent cytotoxicity
against human HeLa cells.