Self-assembly of a hydrophobically modified dextran and controlled drug release in aqueous solution

A narrowly distributed dextran (DEX) sample was modified with octenyl succinic anhydride (OSA) to produce amphiphilic random copolymers (DEX-OSA) with varying degrees of substitution (DS = 0.10-0.80). The micellar structure formed by the DEX-OSA chain was characterized through pyrene-probe fluorescence analysis and small-angle X-ray scattering (SAXS) in aqueous solution. DEX-OSA forms multi-core flower necklace micelles via the single-chain folding into flower micelles, where octenyl side chains aggregate to form hydrophobic cores. The flower necklace of DEX-OSA is stabler up to lower DS than that of OSA-modified pullulan previously studied. The molar concentration of a drug (curcumin) encapsulated by the DEX-OSA micelle in aqueous solution almost linearly increases with the number of glucose residues to make up a unit flower micelle. Such an interrelation between the drug loading and micellar conformation may be important for therapeutic applications.