Center of Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.
Biomaterials. 2010 Jun;31(17):4764-70. doi: 10.1016/j.biomaterials.2010.02.033. Epub 2010 Mar 20.
Silica-coating of positively charged polyplexes was demonstrated through silicic acid condensation to improve the polyplexes for enhanced complex stability and transfection efficiency. Silicic acid was efficiently condensed by polycations to form a silica network in the polyplex through electrostatic interaction and hydrogen bonding. The silica-coated (SC) polyplexes had an anionic surface charge of -20 mV and were 10-20 nm larger in size compared to the non-silica-coated control (+33.4 mV, 106 nm). Silica-coating significantly improved the polyplex stability against both dissociations by counter polyanion exchange and aggregation by salt. The silica network was dissolved to form silicic acid by removing free silicic acid based on the equilibrium, SiO(2) + 2H(2)O right arrow over left arrow Si(OH)(4). Indeed, dialysis of the SC polyplex solution against excess silica-free buffer permitted plasmid DNA release from the silica-coated polyplex, indicating the reversible nature of the silica-layer. The SC polyplex achieved significantly higher transfection efficiency without serious cytotoxicity compared to the polyplex without silica-coating. Detailed examinations of transfection using SC polyplexes revealed that the enhanced transfection efficiency was because of facilitated endosomal escape, possibly due to the protonation of the silica in acidic endosomal compartments. These findings demonstrate the utility of the silica-coating technique for polyplex-mediated gene delivery.
通过硅酸缩合对带正电荷的聚合物进行硅涂层处理，以改善聚合物，提高其复合物稳定性和转染效率。带正电荷的聚合物可有效地将硅酸缩合形成聚合物中的硅网络，这是通过静电相互作用和氢键实现的。硅涂层（SC）聚合物的表面带负电荷为-20 mV，与未硅涂层的对照物（+33.4 mV，106nm）相比，尺寸增加了 10-20nm。硅涂层显著提高了聚合物对通过抗衡聚阴离子交换和盐聚集引起的复合物解离的稳定性。通过去除基于平衡的游离硅酸，可以将硅网络溶解形成硅酸，SiO（2）+2H（2）O ⇌ Si（OH）（4）。实际上，通过过量的无硅缓冲液对 SC 聚合物溶液进行透析，可使质粒 DNA 从硅涂层聚合物中释放出来，这表明硅层具有可逆性。与未硅涂层的聚合物相比，SC 聚合物的转染效率显著提高，而细胞毒性却没有明显增加。对 SC 聚合物转染的详细检查表明，转染效率的提高是由于促进了内涵体逃逸，这可能是由于酸性内涵体隔间中硅的质子化。这些发现证明了硅涂层技术在聚合物介导的基因传递中的实用性。
