New amphiphilic biodegradable β-cyclodextrin/poly(l-leucine) copolymers: Synthesis, characterization, and micellization

A new amphiphilic biodegradable β-cyclodextrin/poly(l-leucine) (β-CD–PLLA) copolymer was synthesized by ring-opening polymerization of N-carboxy-l-alanine anhydride (LL-NCA) in N,N-dimethylformamide (DMF) initiated by mono-6-amino-β-cyclodextrin (H2N-β-CD). The structures of the copolymers were determined by IR, 1H NMR and GPC. The fluorescence technique was used to determine the critical micelle concentrations (CMC) of copolymer micelle solution. The diameter and distribution of micelles were characterized by dynamic light scattering (DLS) and its shape was observed by transmission electron microscopy (TEM). The results showed that LL-NCA could be initiated by H2N-β-CD to produce the copolymer. These copolymers could self-assemble into nano-micelles in water. The CMC of copolymer solution and the size of micelle reduced with increasing proportion of the hydrophobic part. TEM images demonstrated the micelles are all spherical. Such block copolymers could be expected to find applications in drug delivery systems and other biomedical fields.