Preparation and characterization of amphiphilic star copolymers via supramolecular interactions

Over the years, different drug delivery systems have been designed and developed in order to deliver drug to a specific area in a safer manner. Recently, the micelles formed via nonconventional methods have attracted attention. Unlike conventional polymeric micelles, the amphiphilic block copolymers which create these micelles are formed by non-covalent interactions. Among these interactions, supramolecular amphiphiles formed by host-guest interaction exhibit distinctive features as they incorporate macrocyclic host molecules into supramolecular systems. In this study, supraamphiphilic star copolymers were obtained by the inclusion complexation property of cyclodextrin (β-CD) through supramolecular interactions. Micelles were formed with this supraamphiphilic star copolymer and drug delivery efficiency of micelles was investigated. In order to form a 4-armed hydrophobic block, ε-caprolactone monomer was polymerized by ring opening polymerization method using pentaerythritol as the initiator and β-CD was conjugated to the ends of each arms by the click reaction. For the hydrophilic block, 1-adamantylamine (AD) was conjugated to the ends of the PEG chains. By using the host-guest complexation between β-CD and AD, 4-armed star copolymers were formed. The synthesized polymers were characterized by FT-IR, GPC, 1H NMR, 2D 1H NOESY NMR and DSC. Micelles were formed by self-assembly of supramphiphiles using dialysis membrane method and then loaded with doxorubicin (DOX). Particle sizes of DOX loaded and empty micelles were characterized by DLS and their potential was investigated as carriers.