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

• Main Authors: Yi Zhang, Qian Zhao, Hewei Shao, Shiyu Zhang, Xiaoyan Han
• Format: Article
• Language: English
• Published: Hindawi Limited 2014-01-01
• Series: Advances in Materials Science and Engineering
• Online Access: http://dx.doi.org/10.1155/2014/107375

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.