Study on the micellar structure of pullulan modified by dodecenyl succinic anhydride in aqueous solution

Dodecenyl succinic anhydride (DDSA, a relatively longer alkyl chain) was used to hydrophobically modified pullulan (PUL) to obtain the PUL-DDSA with four different DS (degrees of substitution) samples. The micellar structure of PUL-DDSA in 0.05 M NaCl aqueous solution was investigated using two techniques: small-angle X-ray scattering (SAXS) and pyrene-probe fluorescence. Both fluorescence and SAXS data were described by a loose flower-necklace model well. Moreover, the micellar structure of PUL-DDSA prepared in this study distinctly differed from previously reported PUL-OSA, PUL-NSA, and PUL-DCSA (PUL modified with shorter alkyl chains). It exhibited a larger N_0u (monomer number) and lower q_FN (chain stiffness) in the flower-necklace model probably due to its longer alkyl side chains. This study on the micellar structure of PUL-DDSA provides valuable insights for designing optimal gene/drug carrier systems in biomedical materials.