Geometry-induced electrostatic trapping of nanometric objects in a fluid
Geometry-induced electrostatic trapping of nanometric objects in a fluid
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DOI：
10.1038/nature09404
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发表时间：
2010-10-07
期刊：
影响因子：
64.8
通讯作者：
Sandoghdar, Vahid
中科院分区：
文献类型：
--
作者：
Krishnan, Madhavi;Mojarad, Nassiredin;Sandoghdar, Vahid
捕获物体的能力--无论是单个原子还是宏观实体--影响到各种领域，如量子光学(1)、软凝聚态物理、生物物理学和临床医学(2)。已经开发了许多复杂的方法来对抗溶液中布朗运动的随机化效应(3-10)，但稳定捕获纳米大小的对象仍然具有挑战性(8-10)。光镊子是广泛使用的陷阱，但需要足够可极化的物体，因此无法操纵小分子。单分子的限制是通过跟踪荧光标记引导的电动反馈实现的，但光物理约束限制了陷阱的刚性和寿命(8)。在这里，我们展示了具有适当定制的地形的流体狭缝具有空间调制的静电势，可以捕获和悬浮溶液中的带电物体长达几个小时。我们用直径几十纳米的金粒子、聚合物微珠和脂泡来说明这一原理，它们都是在没有外部干预的情况下被捕获的，与它们的质量和介电功能无关。我们的静电捕捉器的硬度和稳定性很容易通过调节系统几何结构和溶液的离子强度来调节，并且它有助于与其他操纵机制的集成。我们预计，这些功能将使其能够用于单个蛋白质和大分子的非接触限制，以及对纳米级物体或其组装成高密度阵列的分选和分级。
The ability to trap an object-whether a single atom or a macroscopic entity-affects fields as diverse as quantum optics(1), soft condensed-matter physics, biophysics and clinical medicine(2). Many sophisticated methodologies have been developed to counter the randomizing effect of Brownian motion in solution(3-10), but stable trapping of nanometre-sized objects remains challenging(8-10). Optical tweezers are widely used traps, but require sufficiently polarizable objects and thus are unable to manipulate small macromolecules. Confinement of single molecules has been achieved using electrokinetic feedback guided by tracking of a fluorescent label, but photophysical constraints limit the trap stiffness and lifetime(8). Here we show that a fluidic slit with appropriately tailored topography has a spatially modulated electrostatic potential that can trap and levitate charged objects in solution for up to several hours. We illustrate this principle with gold particles, polymer beads and lipid vesicles with diameters of tens of nanometres, which are all trapped without external intervention and independently of their mass and dielectric function. The stiffness and stability of our electrostatic trap is easily tuned by adjusting the system geometry and the ionic strength of the solution, and it lends itself to integration with other manipulation mechanisms. We anticipate that these features will allow its use for contact-free confinement of single proteins and macromolecules, and the sorting and fractionation of nanometre-sized objects or their assembly into high-density arrays.