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Advances in Materials Science and Engineering
Volume 2014 (2014), Article ID 107375, 6 pages
http://dx.doi.org/10.1155/2014/107375
Research Article

Synthesis and Characterization of Star-Shaped Block Copolymer sPCL-b-PEG-GA

1Department of Experimental Teaching, Tianjin University of Traditional Chinese Medicine, Tianjin 300193, China
2Tianjin Key Laboratory of Chemistry and Analysis of Chinese Materia Medica, School of Chinese Materia Medica, Tianjin University of Traditional Chinese Medicine, Tianjin 300193, China

Received 28 February 2014; Revised 28 March 2014; Accepted 31 March 2014; Published 27 April 2014

Academic Editor: George Z. Kyzas

Copyright © 2014 Yi Zhang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Compared to linear polymers with the same molecular weight, star-shaped polymers have the superiority of drug loading and delivery. The glycyrrhetinic acid (GA) from licorice is remarkably characteristic of liver distribution and liver cells targetability. In this paper, four-armed star-shaped polycaprolactone was synthesized and amino polyethylene glycol was modified by glycyrrhetinic acid (NH2-PEG-GA). Then the condensation reaction between the two above polymers finally produced four-armed star-shaped poly(ethylene glycol)-b-poly(ε-caprolactone) block copolymer (sPCL-b-PEG-GA). The structures of the intermediates and product were characterized by 1H NMR. The results indicated that the structure and molecular weight of sPCL-b-PEG-GA can be controlled by the varied ratios of pentaerythritol (PTOL) to ε-caprolactone (ε-CL) in the presence of stannous octoate (Sn(Oct)2), and the amphiphilic copolymer sPCL-b-PEG-GA consists of PTOL as core, PCL as inner hydrophobic segments, PEG as external hydrophilic segments, and terminal glycyrrhetic acid as targeting ligand. The work explored a new synthesis route of star poly(ethylene glycol)-b-poly(ε-caprolactone) copolymer with liver targetability. The star-shaped polymer is expected to be an efficient drug carrier.