Biomicrofluidics. 2011 Jun;5(2):24116. doi: 10.1063/1.3604395. Epub 2011 Jun 28.
The manipulation of ribosomal RNA (rRNA) extracted from E. coli cells by dielectrophoresis (DEP) has been demonstrated over the range of 3 kHz-50 MHz using interdigitated microelectrodes. Quantitative measurement using total internal reflection fluorescence microscopy of the time dependent collection indicated a positive DEP response characterized by a plateau between 3 kHz and 1 MHz followed by a decrease in response at higher frequencies. Negative DEP was observed above 9 MHz. The positive DEP response below 1 MHz is described by the Clausius-Mossotti model and corresponds to an induced dipole moment of 3300 D with a polarizability of 7.8×10(-32) F m(2). The negative DEP response above 9 MHz indicates that the rRNA molecules exhibit a net moment of -250 D, to give an effective permittivity value of 78.5 ε(0), close to that of the aqueous suspending medium, and a relatively small surface conductance value of ∼0.1 nS. This suggests that our rRNA samples have a fairly open structure accessible to the surrounding water molecules, with counterions strongly bound to the charged phosphate groups in the rRNA backbone. These results are the first demonstration of DEP for fast capture and release of rRNA units, opening new opportunities for rRNA-based biosensing devices.
利用叉指微电极在 3 kHz-50 MHz 范围内对从大肠杆菌细胞中提取的核糖体 RNA(rRNA)进行介电泳(DEP)的操纵已经得到了证明。使用全内反射荧光显微镜对时间相关收集的定量测量表明，在 3 kHz 和 1 MHz 之间存在正 DEP 响应，随后在更高频率下响应下降。在 9 MHz 以上观察到负 DEP。1 MHz 以下的正 DEP 响应由 Clausius-Mossotti 模型描述，对应于 3300 D 的诱导偶极矩和 7.8×10(-32) F m(2)的极化率。9 MHz 以上的负 DEP 响应表明，rRNA 分子表现出-250 D 的净力矩，从而给出 78.5 ε(0)的有效介电常数值，接近水悬浮介质的值，以及相对较小的表面电导率值∼0.1 nS。这表明我们的 rRNA 样品具有相当开放的结构，可被周围的水分子进入，反离子与 rRNA 骨架中的带电荷的磷酸基团紧密结合。这些结果首次证明了 DEP 可用于快速捕获和释放 rRNA 单元，为基于 rRNA 的生物传感设备开辟了新的机会。
