Matsumoto Satoru, Christie R James, Nishiyama Nobuhiro, Miyata Kanjiro, Ishii Atsushi, Oba Makoto, Koyama Hiroyuki, Yamasaki Yuichi, Kataoka Kazunori
Department of Materials Engineering, Graduate School of Engineering, Center for Disease Biology and Integrative Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan.
Biomacromolecules. 2009 Jan 12;10(1):119-27. doi: 10.1021/bm800985e.
A core-shell-type polyion complex (PIC) micelle with a disulfide cross-linked core was prepared through the assembly of iminothiolane-modified poly(ethylene glycol)-block-poly(L-lysine) [PEG-b-(PLL-IM)] and siRNA at a characteristic optimum mixing ratio. The PIC micelles showed a spherical shape of approximately 60 nm in diameter with a narrow distribution. The micellar structure was maintained at physiological ionic strength but was disrupted under reductive conditions because of the cleavage of disulfide cross-links, which is desirable for siRNA release in the intracellular reductive environment. Importantly, environment-responsive PIC micelles achieved 100-fold higher siRNA transfection efficacy compared with non-cross-linked PICs prepared from PEG-b-poly(L-lysine), which were not stable at physiological ionic strength. PICs formed with PEG-b-(PLL-IM) at nonoptimum ratios did not assemble into micellar structure and did not achieve gene silencing following siRNA transfection. These findings show the feasibility of core cross-linked PIC micelles as carriers for therapeutic siRNA and show that stable micellar structure is critical for effective siRNA delivery into target cells.
通过以特征性最佳混合比例组装亚氨基硫醇修饰的聚（乙二醇）-嵌段-聚（L-赖氨酸）[PEG-b-(PLL-IM)]和siRNA，制备了一种具有二硫键交联核心的核壳型聚离子复合物（PIC）胶束。PIC胶束呈球形，直径约60 nm，分布狭窄。胶束结构在生理离子强度下保持稳定，但在还原条件下会因二硫键交联的断裂而被破坏，这对于在细胞内还原环境中释放siRNA是有利的。重要的是，与由PEG-b-聚（L-赖氨酸）制备的在生理离子强度下不稳定的非交联PIC相比，环境响应性PIC胶束实现了高100倍的siRNA转染效率。以非最佳比例与PEG-b-(PLL-IM)形成的PIC不会组装成胶束结构，并且在siRNA转染后无法实现基因沉默。这些发现表明核交联PIC胶束作为治疗性siRNA载体的可行性，并表明稳定的胶束结构对于将siRNA有效递送至靶细胞至关重要。
