Dam Duncan Hieu M, Lee Hyojin, Lee Raymond C, Kim Ki Hun, Kelleher Neil L, Odom Teri W
Department of Chemistry and ‡Department of Materials Science and Engineering, Northwestern University , 2145 Sheridan Road, Evanston Illinois 60208, United States.
Bioconjug Chem. 2015 Feb 18;26(2):279-85. doi: 10.1021/bc500562s. Epub 2015 Jan 16.
This paper describes how pH can be used to control covalent attachment of oligonucleotides with secondary structure on gold nanoparticles (AuNPs). The highest loading of thiolated nucleic acids occurred at low pH (pH = 1.7) due to reduced repulsion between the negatively charged oligonucleotides and the AuNP surface. The packing of oligonucleotides at low pH decreased (single-stranded ≫ duplex > quadruplex) as the spatial footprint of secondary structure increased. As the pH increased, a decrease in the number of DNA strands grafted to the AuNPs was observed. Notably, the loading density depended on the flexibility and spatial organization of the secondary structures at all pH conditions. At the lowest pH tested, circular dichroism analysis revealed that G-quadruplex aptamers underwent a structural change (from parallel to antiparallel or vice versa), although the biological activity of the aptamer-loaded AuNPs was still maintained. We anticipate that pH-tuning can result in quantitative loading of oligonucleotides on various types of AuNPs with different shapes and surface capping layers.
本文描述了如何利用pH值来控制具有二级结构的寡核苷酸在金纳米颗粒（AuNP）上的共价连接。由于带负电荷的寡核苷酸与AuNP表面之间的排斥力降低，硫醇化核酸的最高负载量出现在低pH值（pH = 1.7）时。随着二级结构空间占用的增加，低pH值下寡核苷酸的堆积减少（单链≫双链>四链体）。随着pH值升高，观察到接枝到AuNP上的DNA链数量减少。值得注意的是，在所有pH条件下，负载密度都取决于二级结构的灵活性和空间组织。在测试的最低pH值下，圆二色性分析表明，G-四链体适体发生了结构变化（从平行到反平行或反之亦然），尽管负载了适体的AuNP的生物活性仍然得以维持。我们预计，pH调节可导致寡核苷酸在具有不同形状和表面封端层的各种类型AuNP上进行定量负载。
