Gitlin Leonid, Schulze Philipp, Ohla Stefan, Bongard Hans-Josef, Belder Detlev
Institut für Analytische Chemie, Universität Leipzig, Leipzig, Germany.
Electrophoresis. 2015 Feb;36(3):449-56. doi: 10.1002/elps.201400269. Epub 2014 Nov 7.
Herein, we present a straightforward surface modification technique for PDMS-based microfluidic devices. The method takes advantage of the high reactivity of concentrated sulfuric acid to enhance the surface properties of PDMS bulk material. This results in alteration of the surface morphology and chemical composition that is in-depth characterized by ATR-FTIR, EDX, SEM, and XPS. In comparison to untreated PDMS, modified substrates exhibit a significantly reduced diffusive uptake of small organic molecules while retaining its low electroosmotic properties. This was demonstrated by exposing the channels of a microfluidic device to concentrated rhodamine B solution followed by fluorescence microscopy. The surface modification procedure was used to improve chip-based electrophoretic separations. Separation efficiencies of FITC-labeled amines/amino acids obtained in treated and untreated PDMS-devices as well as in glass chips were compared. We obtained higher efficiencies in H2 SO4 treated PDMS chips compared to untreated ones but lower efficiencies than those obtained in commercial microfluidic glass devices.
在此，我们展示了一种用于基于聚二甲基硅氧烷（PDMS）的微流控装置的简单表面改性技术。该方法利用浓硫酸的高反应活性来增强PDMS块状材料的表面性能。这导致了表面形态和化学成分的改变，通过衰减全反射傅里叶变换红外光谱（ATR-FTIR）、能量色散X射线光谱（EDX）、扫描电子显微镜（SEM）和X射线光电子能谱（XPS）对其进行了深入表征。与未处理的PDMS相比，改性后的基底对小分子有机化合物的扩散吸收显著降低，同时保留了其低电渗特性。通过将微流控装置的通道暴露于浓罗丹明B溶液中，然后进行荧光显微镜观察，证实了这一点。表面改性程序用于改善基于芯片的电泳分离。比较了在处理过和未处理的PDMS装置以及玻璃芯片中获得的异硫氰酸荧光素（FITC）标记的胺/氨基酸的分离效率。与未处理的芯片相比，我们在硫酸处理的PDMS芯片中获得了更高的效率，但比在商用微流控玻璃装置中获得的效率低。
