Zhou Ronghui, Wang Ping, Chang Hsueh-Chia
Department of Chemical and Biomolecular Engineering, Center for Micro-fluidics and Medical Diagnostics, University of Notre Dame, Notre Dame, IN 46556, USA.
Electrophoresis. 2006 Apr;27(7):1376-85. doi: 10.1002/elps.200500329.
The high polarizability and dielectrophoretic mobility of single-walled carbon nanotubes (SWNT) are utilized to capture and detect low numbers of bacteria and submicron particles in milliliter-sized samples. Concentrated SWNT solutions are mixed with the sample and a high-frequency (>100 kHz) alternating current (AC) field is applied by a microelectrode array to enhance bulk absorption of the particles (bacteria and nanoparticle substitutes) by the SWNTs via dipole-dipole interaction. The same AC field then drives the SWNT-bacteria aggregates to the microelectrode array by positive-AC dielectrophoresis (DEP), with enhanced and reversed bacteria DEP mobility due to the attached SWNTs. Since the field frequency exceeds the inverse RC time of the electrode double layer, the AC field penetrates deeply into the bulk and across the electrode gap. Consequently, the SWNTs and absorbed bacteria assemble rapidly (<5 min) into conducting linear aggregates between the electrodes. Measured AC impedance spectra by the same trapping electrodes and fields show a detection threshold of 10(4) bacteria/mL with this pathogen trapping and concentration technique.
单壁碳纳米管（SWNT）的高极化率和介电泳迁移率被用于捕获和检测毫升级样品中少量的细菌和亚微米颗粒。将浓缩的SWNT溶液与样品混合，并通过微电极阵列施加高频（>100 kHz）交流电（AC）场，以通过偶极-偶极相互作用增强SWNT对颗粒（细菌和纳米颗粒替代物）的整体吸收。然后，相同的交流电场通过正交流电介电泳（DEP）将SWNT-细菌聚集体驱动到微电极阵列，由于附着的SWNT，细菌的DEP迁移率增强且方向相反。由于场频率超过电极双层的反向RC时间，交流电场可深入穿透到主体中并穿过电极间隙。因此，SWNT和被吸收的细菌在电极之间迅速（<5分钟）组装成导电线性聚集体。使用相同的捕获电极和电场测量的交流阻抗谱表明，这种病原体捕获和浓缩技术的检测阈值为10⁴个细菌/毫升。
