Li Michelle W, Martin R Scott
Department of Chemistry, Saint Louis University, St. Louis, MO 63103, USA.
Electrophoresis. 2007 Jul;28(14):2478-88. doi: 10.1002/elps.200600713.
Here we describe a reversibly sealed microchip device that incorporates poly(dimethylsiloxane) (PDMS)-based valves for the rapid injection of analytes from a continuously flowing stream into a channel network for analysis with microchip electrophoresis. The microchip was reversibly sealed to a PDMS-coated glass substrate and microbore tubing was used for the introduction of gas and fluids to the microchip device. Two pneumatic valves were incorporated into the design and actuated on the order of hundreds of milliseconds, allowing analyte from a continuously flowing sampling stream to be injected into an electrophoresis separation channel. The device was characterized in terms of the valve actuation time and pushback voltage. It was also found that the addition of sodium dodecyl sulfate (SDS) to the buffer system greatly increased the reproducibility of the injection scheme and enabled the analysis of amino acids derivatized with naphthalene-2,3-dicarboxaldehyde/cyanide. Results from continuous injections of a 0.39 nL fluorescein plug into the optimized system showed that the injection process was reproducible (RSD of 0.7%, n = 10). Studies also showed that the device was capable of monitoring off-chip changes in concentration with a device lag time of 90 s. Finally, the ability of the device to rapidly monitor on-chip concentration changes was demonstrated by continually sampling from an analyte plug that was derivatized upstream from the electrophoresis/continuous flow interface. A reversibly sealed device of this type will be useful for the continuous monitoring and analysis of processes that occur either off-chip (such as microdialysis sampling) or on-chip from other integrated functions.
在此，我们描述了一种可逆密封的微芯片装置，该装置集成了基于聚二甲基硅氧烷（PDMS）的阀门，用于将连续流动的样品流中的分析物快速注入通道网络，以便通过微芯片电泳进行分析。该微芯片可逆地密封在涂有PDMS的玻璃基板上，微孔管用于向微芯片装置引入气体和流体。设计中集成了两个气动阀，其响应时间约为数百毫秒，可将连续流动的采样流中的分析物注入电泳分离通道。该装置通过阀门响应时间和回推电压进行表征。还发现，在缓冲系统中添加十二烷基硫酸钠（SDS）可大大提高进样方案的重现性，并能够分析用萘-2,3-二甲醛/氰化物衍生化的氨基酸。向优化系统中连续注入0.39 nL荧光素塞的结果表明，进样过程具有可重复性（相对标准偏差为0.7%，n = 10）。研究还表明，该装置能够以90 s的装置滞后时间监测芯片外浓度变化。最后，通过从电泳/连续流界面上游衍生化的分析物塞中持续采样，证明了该装置快速监测芯片上浓度变化的能力。这种类型的可逆密封装置将有助于对芯片外（如微透析采样）或来自其他集成功能的芯片上发生的过程进行连续监测和分析。
