Sutter Eli, Zhang Bo, Sutter Peter
Department of Mechanical & Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588, United States.
Department of Mechanical & Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588, United States.
J Colloid Interface Sci. 2021 Mar 15;586:847-854. doi: 10.1016/j.jcis.2020.11.009. Epub 2020 Nov 5.
Directed self-assembly uses different stimuli to initiate and control the interaction between nanocrystals. Protonation at reduced pH represents a convenient stimulus for initiating self-assembly. Prior work has focused on protonation-induced hydrogen bonding between peptide or amino acid functionalized nanocrystals for reversible cycling between dispersed and aggregated states. Here, we discuss a fundamentally different approach, in which changes in pH modify the nonspecific interparticle interaction between Au nanorods conjugated with single-stranded (ss) DNA. While electrostatic repulsion stabilizes dispersed suspensions at neutral pH, protonation in acidic solution modifies the DNA corona, turning the interaction between the rods attractive and triggering their self-assembly. Analysis of in-situ electron microscopy of ssDNA-Au nanorods in solution is consistent with a van der Waals attraction of charge-neutral monomers at acidic pH. The results demonstrate ssDNA-conjugated anisotropic nanostructures as versatile building blocks with stimuli-programmable interactions for on-demand self-assembly.
定向自组装利用不同的刺激来引发和控制纳米晶体之间的相互作用。在较低pH值下的质子化是引发自组装的一种便利刺激。先前的工作主要集中在质子化诱导的肽或氨基酸功能化纳米晶体之间的氢键作用，以实现分散态和聚集态之间的可逆循环。在此，我们讨论一种根本不同的方法，其中pH值的变化改变了与单链（ss）DNA共轭的金纳米棒之间的非特异性颗粒间相互作用。虽然静电排斥在中性pH值下稳定分散的悬浮液，但酸性溶液中的质子化会改变DNA晕圈，使棒之间的相互作用具有吸引力并引发它们的自组装。对溶液中ssDNA-金纳米棒的原位电子显微镜分析与酸性pH值下电荷中性单体的范德华吸引力一致。结果表明，ssDNA共轭的各向异性纳米结构是具有刺激可编程相互作用的通用构建块，可用于按需自组装。
