Luo Yiqi, Huang Bo, Wu Hongkai, Zare Richard N
Department of Chemistry, Stanford University, Stanford, California 94305-5080, USA.
Anal Chem. 2006 Jul 1;78(13):4588-92. doi: 10.1021/ac052274g.
The electroosmotic flow (EOF) in a poly(dimethylsiloxane) (PDMS) separation channel can be altered and controlled by adding a carboxylic acid to the prepolymer prior to curing. When the prepolymer is doped with 0.5 wt % undecylenic acid (UDA), the electroosmotic mobility in a modified PDMS channel rises to (7.6 +/- 0.2) x 10(-4) cm(2) V(-1) s(-1) (in HEPES buffer at pH 8.5), which is nearly twice that in the native PDMS channel. Because this modification does not significantly change the hydrophobicity of the PDMS surface, it is possible to combine the modified PDMS with a dynamic coating of n-dodecyl beta-d-maltoside (DDM), which prevents protein sticking (see Huang, B.; Wu, H. K.; Kim, S.; Zare, R. N. Lab Chip 2005, 5, 1005-1007). The modified PDMS channel with a dynamic coating of DDM generates an electroosmotic mobility of (5.01 +/- 0.09) x 10(-4) cm(2) V(-1) s(-1), which shows excellent reproducibility both in successive runs and during storage in water. Combining this surface modification and the dynamic coating of DDM is an effective means for both providing stable EOF in the PDMS channels and preventing protein adsorption on the channel walls. To demonstrate these effects, we show that the electrophoretic separation of immunocomplexes in free solution can be readily accomplished in a microfluidic chip made of UDA-doped (0.5 wt %) PDMS with a dynamic coating of DDM.
在聚二甲基硅氧烷（PDMS）分离通道中的电渗流（EOF）可以通过在固化前向预聚物中添加羧酸来改变和控制。当预聚物掺杂0.5 wt%的十一烯酸（UDA）时，改性PDMS通道中的电渗迁移率升至(7.6±0.2)×10⁻⁴ cm² V⁻¹ s⁻¹（在pH 8.5的HEPES缓冲液中），这几乎是天然PDMS通道中电渗迁移率的两倍。由于这种改性不会显著改变PDMS表面的疏水性，因此可以将改性PDMS与正十二烷基-β-D-麦芽糖苷（DDM）的动态涂层相结合，从而防止蛋白质粘附（见Huang, B.; Wu, H. K.; Kim, S.; Zare, R. N. Lab Chip 2005, 5, 1005 - 1007）。具有DDM动态涂层的改性PDMS通道产生的电渗迁移率为(5.01±0.09)×10⁻⁴ cm² V⁻¹ s⁻¹，在连续运行和在水中储存期间均表现出出色的重现性。将这种表面改性与DDM的动态涂层相结合，是在PDMS通道中提供稳定EOF并防止蛋白质吸附在通道壁上的有效方法。为了证明这些效果，我们表明在由掺杂0.5 wt% UDA的PDMS制成并带有DDM动态涂层的微流控芯片中，可以很容易地实现游离溶液中免疫复合物的电泳分离。
