Enantiomeric PLA–PEG block copolymers and their stereocomplex micelles used as rifampin delivery |
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Authors: | Li Chen Zhigang Xie Junli Hu Xuesi Chen Xiabin Jing |
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Institution: | (1) State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Changchun, 130022, China;(2) Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 100039, China;(3) Department of Chemistry, Northeast Normal University, Changchun, 130022, P.R. China |
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Abstract: | A novelty approach to self-assembling stereocomplex micelles by enantiomeric PLA–PEG block copolymers as a drug delivery carrier
was described. The particles were encapsulated by enantiomeric PLA–PEG stereocomplex to form nanoscale micelles different
from the microspheres or the single micelles by PLLA or PDLA in the reported literatures. First, the block copolymers of enantiomeric
poly(l-lactide)–poly(ethylene–glycol) (PLLA–PEG) and poly(D-lactide)–poly(ethylene–glycol) (PDLA–PEG) were synthesized by the ring-opening polymerization of l-lactide and d-lactide in the presence of monomethoxy PEG, respectively. Second, the stereocomplex block copolymer micelles were obtained
by the self-assembly of the equimolar mixtures of enantiomeric PLA–PEG copolymers in water. These micelles possessed partially
the crystallized hydrophobic cores with the critical micelle concentrations (cmc) in the range of 0.8–4.8 mg/l and the mean
hydrodynamic diameters ranging from 40 to 120 nm. The micelle sizes and cmc values obviously depended on the hydrophobic block
PLA content in the copolymer. Compared with the single PLLA–PEG or PDLA–PEG micelles, the cmc values of the stereocomplex
micelles became lower and the sizes of the stereocomplex micelles formed smaller. And lastly, the stereocomplex micelles encapsulated
with rifampin were tested for the controlled release application. The rifampin loading capacity and encapsulation efficiency
by the stereocomplex micelles were higher than those by the single polymer micelles, respectively. The drug release time in vitro was depending on the composites of the block copolymers and also could be controlled by the polymer molecular weight and
the morphology of the polymer micelles. |
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Keywords: | PLLA– PEG PDLA– PEG stereocomplex micelle rifampin drug delivery controlled release nanobiomedicine nanotechnology |
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