Foley Jennifer, Schmid Heinz, Stutz Richard, Delamarche Emmanuel
IBM Research GmbH, Zurich Research Laboratory, 8803 Rüschlikon, Switzerland.
Langmuir. 2005 Nov 22;21(24):11296-303. doi: 10.1021/la0518142.
Microfluidic devices are well suited for the miniaturization of biological assays, in particular when only small volumes of samples and reagents are available, short time to results is desirable, and multiple analytes are to be detected. Microfluidic networks (MFNs), which fill by means of capillary forces, have already been used to detect important biological analytes with high sensitivity and in a combinatorial fashion. These MFNs were coated with Au, onto which a hydrophilic, protein-repellent monolayer of thiolated poly(ethyleneglycol) (HS-PEG) was self-assembled, and the binding sites for analytes were present on a poly(dimethylsiloxane) (PDMS) sealing cover. We report here a set of simple methods to extend previous work on MFNs by integrating binding sites for analytes inside the microstructures of MFNs using microcontact printing (muCP). First, fluorescently labeled antibodies (Abs) were microcontact-printed from stamps onto planar model surfaces such as glass, Si, Si/SiO2, Au, and Au derivatized with HS-PEG to investigate how much candidate materials for MFNs would quench the fluorescence of printed, labeled Abs. Au coated with HS-PEG led to a fluorescence signal that was approximately 65% weaker than that of glass but provided a convenient surface for printing Abs and for rendering the microstructures of the MFNs wettable. Then, proteins were inked from solution onto the surface of PDMS (Sylgard 184) stamps having continuous or discontinuous micropatterns or locally inked onto planar stamps to investigate how the aspect ratio (depth:width) of microstructures and the printing conditions affected the transfer of protein and the accuracy of the resulting patterns. By applying a controlled pressure to the back of the stamp, Abs were accurately microcontact-printed into the recessed regions of MFNs if the aspect ratio of the MFN microstructures was lower than approximately 1:6. Finally, the realization of a simple assay between Abs (used as antigens) microcontact-printed in microchannels and Abs from solution suggests that this method could become useful to pattern proteins in microstructures for advanced bioanalytical purposes.
微流控装置非常适合生物分析的小型化，特别是当只有少量样品和试剂可用、需要短时间出结果且要检测多种分析物时。通过毛细作用力填充的微流控网络（MFN）已被用于以高灵敏度和组合方式检测重要的生物分析物。这些MFN涂有金，在金上自组装了一层亲水性、排斥蛋白质的硫醇化聚乙二醇（HS-PEG）单分子层，分析物的结合位点存在于聚二甲基硅氧烷（PDMS）密封盖上。我们在此报告了一组简单的方法，通过使用微接触印刷（μCP）将分析物的结合位点整合到MFN的微结构内部，从而扩展了先前关于MFN的工作。首先，将荧光标记的抗体（Ab）从印章微接触印刷到平面模型表面，如玻璃、硅、Si/SiO2、金以及用HS-PEG衍生化的金上，以研究MFN的候选材料对印刷的标记抗体荧光的淬灭程度。涂有HS-PEG的金产生的荧光信号比玻璃上的弱约65%，但为印刷抗体和使MFN的微结构具有可润湿性提供了便利的表面。然后，将蛋白质从溶液中印到具有连续或不连续微图案的PDMS（Sylgard 184）印章表面，或局部印到平面印章上，以研究微结构的纵横比（深度：宽度）和印刷条件如何影响蛋白质的转移以及所得图案的准确性。如果MFN微结构的纵横比低于约1:6，通过对印章背面施加可控压力，可将抗体准确地微接触印刷到MFN的凹陷区域。最后，在微通道中微接触印刷的抗体（用作抗原）与溶液中的抗体之间实现的简单分析表明，该方法对于在微结构中对蛋白质进行图案化以用于先进的生物分析目的可能会很有用。
