title: Synchrotron Small-Angle X-ray Scattering Study of Cross-Linked Polymeric Micelles.
abstract: Polymeric micelles of methoxypoly(ethylene glycol)-b-poly(lactide) containing lysine units (mPEG-PLA-Lys4) were cross-linked by reacting of lysine moieties with a bifunctional bis(N-hydroxy-succinimide ester). The micelles were characterized in aqueous solution using dynamic light scattering, transmission electron microscopy, and synchrotron small-angle X-ray scattering. The mPEG-PLA-Lys4 was synthesized through the ring-opening polymerization of N6-carbobenzyloxy-L-lysine N-carboxyanhydride with amine-terminated mPEG-PLA and subsequent deprotection. The polymeric micelles showed enhanced micelle stability after cross-linking, which was confirmed by adding sodium dodecyl sulfate as a destabilizing agent. The average diameters measured via dynamic light scattering were 19.1 nm and 29.2 nm for non-cross-linked polymeric micelles (NCPMs) and cross-linked polymeric micelles (CPMs), respectively. The transmission electron microscopy images showed that the size of the polymeric micelles increased slightly due to cross-linking, which was in good agreement with the DLS measurements. The overall structures and internal structural changes of NCPMs and CPMs in aqueous solution were studied in detail using synchrotron X-ray scattering method. According to the structural parameters of X-ray scattering analysis, CPMs with a more densely packed core structure were formed by reacting bifunctional cross-linking agents with lysine amino groups located in the innermost core of the polymeric micelles.
authors.forename: Hyun-Chul
authors.initials: HC
authors.lastname: Kim
authors.forename: Kyeong Sik
authors.initials: KS
authors.lastname: Jin
authors.forename: Se Guen
authors.initials: SG
authors.lastname: Lee
authors.forename: Eunjoo
authors.initials: E
authors.lastname: Kim
authors.forename: Sung Jun
authors.initials: SJ
authors.lastname: Lee
authors.forename: Sang Won
authors.initials: SW
authors.lastname: Jeong
authors.forename: Seung Woo
authors.initials: SW
authors.lastname: Lee
authors.forename: Kwang-Woo
authors.initials: KW
authors.lastname: Kim