Department of Mechanical Engineering, Northwestern University, Evanston, IL, USA.
Nanoscale. 2012 Aug 21;4(16):5189-94. doi: 10.1039/c2nr31279d. Epub 2012 Jul 18.
The concentration and detection of molecular biomarkers remain as a challenge to develop point-of-care diagnostic devices. An electric field induced concentration has been studied for such purposes but with limited success due to limited efficacy. This paper presents a computational study for investigating the molecular concentration and retention efficacy of single nanowire (SNW) and dendritic nanotip (DNT) sensors. Our computational results indicate that compared to a DNT, the SNW sensor produces higher dielectrophoretic (DEP) forces in the vicinity of the terminal end of the tip. Furthermore, the magnitude of the DEP force increases exponentially as the diameter of the SNW is decreased, resulting in a further improved retention efficacy of NPs. However, the SNW sensor's concentration efficacy was not much improved for NPs smaller than 10 nm diameter when the nanowire diameter was reduced from 500 to 50 nm. Compared to the SNW, the DNT sensor showed improved concentration efficacy due to multiple points of electric field concentrations, which retard the exponential decay of the DEP force resulting in a greater widespread region where the DEP force dominates the Brownian motion forces. When oligonucleotides are used as a target particle, the DEP force can be used to elongate oligonucleotides to further enhance the concentration and retention efficacy.
在开发即时诊断设备时，分子生物标志物的浓度和检测仍然是一个挑战。已经研究了电场诱导浓缩以达到此目的，但由于效果有限，因此效果有限。本文提出了一种计算研究，用于研究单纳米线（SNW）和树枝状纳尖端（DNT）传感器的分子浓缩和保留效率。我们的计算结果表明，与 DNT 相比，SNW 传感器在尖端末端附近产生更高的介电泳（DEP）力。此外，随着 SNW 直径的减小，DEP 力的大小呈指数增长，从而进一步提高了 NPs 的保留效率。但是，当纳米线直径从 500nm 减小到 50nm 时，对于直径小于 10nm 的 NPs，SNW 传感器的浓度效率并没有得到很大提高。与 SNW 相比，由于电场的多个集中点，DNT 传感器显示出了改进的浓缩效果，这减缓了 DEP 力的指数衰减，从而使 DEP 力主导布朗运动力的广泛区域更大。当使用寡核苷酸作为靶粒子时，可以使用 DEP 力来延长寡核苷酸以进一步增强浓缩和保留效率。
