Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo , Tokyo 113-8656, Japan.
ACS Nano. 2014 Sep 23;8(9):8979-91. doi: 10.1021/nn502125h. Epub 2014 Aug 22.
For systemic delivery of siRNA to solid tumors, a size-regulated and reversibly stabilized nanoarchitecture was constructed by using a 20 kDa siRNA-loaded unimer polyion complex (uPIC) and 20 nm gold nanoparticle (AuNP). The uPIC was selectively prepared by charge-matched polyionic complexation of a poly(ethylene glycol)-b-poly(L-lysine) (PEG-PLL) copolymer bearing ∼40 positive charges (and thiol group at the ω-end) with a single siRNA bearing 40 negative charges. The thiol group at the ω-end of PEG-PLL further enabled successful conjugation of the uPICs onto the single AuNP through coordinate bonding, generating a nanoarchitecture (uPIC-AuNP) with a size of 38 nm and a narrow size distribution. In contrast, mixing thiolated PEG-PLLs and AuNPs produced a large aggregate in the absence of siRNA, suggesting the essential role of the preformed uPIC in the formation of nanoarchitecture. The smart uPIC-AuNPs were stable in serum-containing media and more resistant against heparin-induced counter polyanion exchange, compared to uPICs alone. On the other hand, the treatment of uPIC-AuNPs with an intracellular concentration of glutathione substantially compromised their stability and triggered the release of siRNA, demonstrating the reversible stability of these nanoarchitectures relative to thiol exchange and negatively charged AuNP surface. The uPIC-AuNPs efficiently delivered siRNA into cultured cancer cells, facilitating significant sequence-specific gene silencing without cytotoxicity. Systemically administered uPIC-AuNPs showed appreciably longer blood circulation time compared to controls, i.e., bare AuNPs and uPICs, indicating that the conjugation of uPICs onto AuNP was crucial for enhancing blood circulation time. Finally, the uPIC-AuNPs efficiently accumulated in a subcutaneously inoculated luciferase-expressing cervical cancer (HeLa-Luc) model and achieved significant luciferase gene silencing in the tumor tissue. These results demonstrate the strong potential of uPIC-AuNP nanoarchitectures for systemic siRNA delivery to solid tumors.
为了将 siRNA 递送到实体瘤中，构建了一种尺寸可调且可还原稳定的纳米结构，该结构使用负载 20 kDa siRNA 的单聚体聚离子复合物 (uPIC) 和 20nm 金纳米颗粒 (AuNP)。uPIC 通过带约 40 个正电荷（和 ω 端的巯基）的聚乙二醇-b-聚 L-赖氨酸（PEG-PLL）共聚物与带 40 个负电荷的单个 siRNA 的电荷匹配聚离子复合来选择性制备。PEG-PLL 的 ω 端的巯基进一步通过配位键成功地将 uPIC 连接到单个 AuNP 上，生成了一种尺寸为 38nm 且尺寸分布较窄的纳米结构 (uPIC-AuNP)。相比之下，在没有 siRNA 的情况下，混合巯基化的 PEG-PLL 和 AuNP 会产生大的聚集体，这表明预形成的 uPIC 在纳米结构的形成中起着重要作用。与单独的 uPIC 相比，智能 uPIC-AuNP 在含血清的介质中稳定，并且更能抵抗肝素诱导的聚阴离子交换。另一方面，用细胞内浓度的谷胱甘肽处理 uPIC-AuNP 会大大破坏其稳定性并触发 siRNA 的释放，这表明与巯基交换和带负电荷的 AuNP 表面相比，这些纳米结构具有可逆的稳定性。uPIC-AuNP 有效地将 siRNA 递送到培养的癌细胞中，在没有细胞毒性的情况下促进了显著的序列特异性基因沉默。与对照组相比，即裸 AuNP 和 uPIC，系统给予的 uPIC-AuNP 显示出明显更长的血液循环时间，表明 uPIC 与 AuNP 的连接对于延长血液循环时间至关重要。最后，uPIC-AuNP 有效地积聚在皮下接种的表达荧光素酶的宫颈癌（HeLa-Luc）模型中，并在肿瘤组织中实现了显著的荧光素酶基因沉默。这些结果表明 uPIC-AuNP 纳米结构在将 siRNA 递送到实体瘤中的系统给药方面具有很大的潜力。
