Department of Bioengineering and Dalton Cardiovascular Research Center, University of Missouri , Columbia, Missouri 65211, United States.
Department of Physics, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
ACS Nano. 2017 Feb 28;11(2):1204-1213. doi: 10.1021/acsnano.6b07570. Epub 2017 Jan 6.
The motion of polarizable particles in a nonuniform electric field (i.e., dielectrophoresis) has been extensively used for concentration, separation, sorting, and transport of biological particles from cancer cells and viruses to biomolecules such as DNAs and proteins. However, current approaches to dielectrophoretic manipulation are not sensitive enough to selectively target individual molecular species. Here, we describe the application of the dielectrophoretic principle for selective detection of DNA and RNA molecules using an engineered biological nanopore. The key element of our approach is a synthetic polycationic nanocarrier that selectively binds to the target biomolecules, dramatically increasing their dielectrophoretic response to the electric field gradient generated by the nanopore. The dielectrophoretic capture of the nanocarrier-target complexes is detected as a transient blockade of the nanopore ionic current, while any nontarget nucleic acids are repelled from the nanopore by electrophoresis and thus do not interfere with the signal produced by the target's capture. Strikingly, we show that even modestly charged nanocarriers can be used to capture DNA or RNA molecules of any length or secondary structure and simultaneously detect several molecular targets. Such selective, multiplex molecular detection technology would be highly desirable for real-time analysis of complex clinical samples.
在非均匀电场中（即介电泳），可极化粒子的运动已被广泛用于生物粒子（从癌细胞和病毒到生物分子如 DNA 和蛋白质）的浓缩、分离、分类和输送。然而，目前的介电泳操作方法不够灵敏，无法选择性地针对单个分子种类。在这里，我们描述了利用工程化生物纳米孔选择性检测 DNA 和 RNA 分子的介电泳原理。我们方法的关键要素是一种合成的聚阳离子纳米载体，它能选择性地与靶生物分子结合，显著提高它们对纳米孔产生的电场梯度的介电泳响应。纳米载体-靶复合物的介电泳捕获被检测为纳米孔离子电流的瞬时阻断，而任何非靶核酸则通过电泳被排斥出纳米孔，因此不会干扰靶捕获产生的信号。引人注目的是，我们表明，即使是带轻微电荷的纳米载体也可用于捕获任何长度或二级结构的 DNA 或 RNA 分子，同时检测多个分子靶标。这种选择性的、多重分子检测技术对于实时分析复杂的临床样本非常理想。
