Computational Biophysics Group, Research School of Biology, Australian National University, Acton, ACT 0200, Australia.
Sensors (Basel). 2012 Oct 12;12(10):13720-35. doi: 10.3390/s121013720.
Carbon nanotubes offer exciting opportunities for devising highly-sensitive detectors of specific molecules in biology and the environment. Detection limits as low as 10(-11) M have already been achieved using nanotube-based sensors. We propose the design of a biosensor comprised of functionalized carbon nanotube pores embedded in a silicon-nitride or other membrane, fluorofullerene-Fragment antigen-binding (Fab fragment) conjugates, and polymer beads with complementary Fab fragments. We show by using molecular and stochastic dynamics that conduction through the (9, 9) exohydrogenated carbon nanotubes is 20 times larger than through the Ion Channel Switch ICS(TM) biosensor, and fluorofullerenes block the nanotube entrance with a dissociation constant as low as 37 pM. Under normal operating conditions and in the absence of analyte, fluorofullerenes block the nanotube pores and the polymer beads float around in the reservoir. When analyte is injected into the reservoir the Fab fragments attached to the fluorofullerene and polymer bead crosslink to the analyte. The drag of the much larger polymer bead then acts to pull the fluorofullerene from the nanotube entrance, thereby allowing the flow of monovalent cations across the membrane. Assuming a tight seal is formed between the two reservoirs, such a biosensor would be able to detect one channel opening and thus one molecule of analyte making it a highly sensitive detection design.
碳纳米管为设计生物和环境中特定分子的高灵敏度探测器提供了令人兴奋的机会。使用基于纳米管的传感器已经实现了低至 10(-11) M 的检测极限。我们提出了一种生物传感器的设计，该传感器由嵌入在氮化硅或其他膜中的功能化碳纳米管孔、氟富勒烯-Fragment 抗原结合 (Fab 片段) 缀合物以及具有互补 Fab 片段的聚合物珠组成。我们通过使用分子和随机动力学表明，(9,9)外氢化碳纳米管的传导比 Ion Channel Switch ICS(TM) 生物传感器大 20 倍，而氟富勒烯的解离常数低至 37 pM 就可以阻止纳米管入口。在正常工作条件下且不存在分析物时，氟富勒烯会阻止纳米管孔，聚合物珠在储液器中漂浮。当分析物注入储液器时，与氟富勒烯和聚合物珠相连的 Fab 片段会与分析物交联。然后，聚合物珠的较大阻力会将氟富勒烯从纳米管入口中拉出，从而允许单价阳离子穿过膜流动。假设两个储液器之间形成了紧密的密封，这样的生物传感器将能够检测到一个通道的开启，从而检测到一个分析物分子，使其成为一种高灵敏度的检测设计。
