磁等离子体纳米孔中粒子捕获的控制
Control of particle trapping in a magnetoplasmonic nanopore
摘要：
等离子体纳米孔作为单分子检测器被广泛研究。等离子体纳米孔技术的主要局限性是分子通过孔的过快移位速度和随之而来的非常短的分析时间，以及由于局部加热而可能的不稳定性。控制分子移位和实现更长采集时间的最有趣方法是有效捕获和调节可用于标记分子的纳米颗粒运动的能力。在这里，我们从理论上研究了磁等离子体纳米孔的性能，该纳米孔是用夹在两个金层之间的薄钴层制备的。然后将纳米孔与易位磁性纳米颗粒偶联。通过由外部磁场设置孔周围的钴层的磁性配置，可以产生纳米级磁性镊子以在特定点处捕获纳米颗粒。考虑到10 nm的磁铁矿纳米颗粒，我们计算的捕获力高达28 pN，一个数量级以上的力，可以获得与标准的光学或等离子体捕获方法。此外，磁力拉动纳米颗粒与等离子体纳米孔的壁紧密接触，从而使得能够形成包围深亚波长限制的电磁场的纳米腔，该电磁场在近红外波长处具有高达230的平均场强增强。所提出的混合磁等离子体系统指向一种策略，以改善基于纳米孔的生物传感器的单分子检测和潜在的各种生物分子的分析。
英文摘要：
Plasmonic nanopores are extensively investigated as single molecules detectors. The main limitations in plasmonic nanopore technology are the too fast translocation velocity of the molecule through the pore and the consequent very short analysis times, as well as the possible instabilities due to local heating. The most interesting approach to control the translocation of molecules and enable longer acquisition times is represented by the ability to efficiently trap and tune the motion of nanoparticles that can be used to tag molecules. Here, we theoretically investigate the performance of a magneto-plasmonic nanopore prepared with a thin layer of cobalt sandwiched between two gold layers. A nanopore is then coupled with a translocating magnetic nanoparticle. By setting the magnetic configuration of the cobalt layer around the pore by an external magnetic field, it is possible to generate a nanoscale magnetic tweezer to trap the nanoparticle at a specific point. Considering a 10 nm magnetite nanoparticle we calculate a trapping force up to 28 pN, an order of magnitude above the force that can be obtained with standard optical or plasmonic trapping approaches. Moreover, the magnetic force pulls the nanoparticle in close contact with the plasmonic nanopore's wall, thus enabling the formation of a nanocavity enclosing a deeply sub-wavelength confined electromagnetic field with an average field intensity enhancement up to 230 at near-infrared wavelengths. The presented hybrid magneto-plasmonic system points towards a strategy to improve nanopore-based biosensors for single-molecule detection and potentially for analysis of various biomolecules.
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