Self-Assembled Micellar Aggregates From Star-Shaped Copolymers Decorated With Cholesterol

Abstract

In this work, we synthesized star-shaped triblock copolymers based on poly(ε-caprolactone) (PCL), poly(2-hydroxyethyl acrylate) (PHEA), and poly(N-acryloyl D-glucosamine) (PAGA). PCL macro-RAFT agent was chain extended with 2-hydroxyethyl acrylate (HEA) via RAFT polymerization, followed by N-acryloyl D-glucosamine (AGA) to achieve the triblock. The length of the PHEA block was varied from DP = 2–59 per arm. The self-assembly behavior of PCL-b-PHEA diblock copolymer was studied in deionized water. By AFM, large semi-spherical micellar aggregates with a diameter of approximately 318–238 nm were observed. Some of these copolymers were decorated with cholesterol. PHEA block was mainly incorporated as a template to anchor cholesterol (Chol) and provide amphiphilic properties to the diblock, facilitating efficient extension of polymerization of AGA. The content of cholesterol conjugated in the PHEA block was 2.5%. It was found that the micellar aggregates prepared with the cholesterol-decorated diblock practically tripled their diameter. By introducing the PAGA block, the micellar aggregates reduced their size (111–136 nm in diameter), improved colloidal stability, and turned into a material with unique characteristics that can be used as nanocarriers of therapeutic agents.