Yu Xiaoling, Xiao Junzhu, Dang Fuquan
Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province, School of Chemistry and Chemical Engineering, Shaanxi Normal University, 620 West Chang'an Street, Xi'an 710119, China.
Langmuir. 2015 Jun 2;31(21):5891-8. doi: 10.1021/acs.langmuir.5b01085. Epub 2015 May 20.
Poly(dimethylsiloxane) (PDMS) has become a widely used material for microfluidic and biological applications. However, PDMS has unacceptably high levels of nonspecific protein adsorption, which significantly lowers the performance of PDMS-based microfluidic chips. Most existing methods to reduce protein fouling of PDMS are to make the surface more hydrophilic by surface oxidization, polymer grafting, and physisorbed coatings. These methods suffer from the relatively short-term stability, the multistep complex treatment procedure, or the insufficient adsorption reduction. Herein, we developed a novel and facile modification method based on self-assembled peptides with well-tailored amino acid composition and sequence, which can also interact strongly with the PDMS surface in the same way as proteins, for suppressing the nonspecific protein fouling and improving the biocompatibility of PDMS-based microfluidic chips. We first demonstrated that an ionic complementary peptide, EAR16-II with a sequence of [(Ala-Glu-Ala-Glu-Ala-Arg-Ala-Arg)2], can readily self-assemble into an amphipathic film predominantly composed of tightly packed β-sheets on the native hydrophobic and plasma-oxidized hydrophilic PDMS surfaces upon low concentrations of carbohydrates. The self-assembled EAR16-II amphipathic film exposed its hydrophobic side to the solution and thus rendered the PDMS surface hydrophobic with water contact angles (WCAs) of around 110.0°. However, the self-assembled EAR16-II amphipathic film exhibited excellent protein-repelling and blood compatibility properties comparable to or better than those obtained with previously reported methods. A schematic model has been proposed to explain the interactions of EAR16-II with the PDMS surface and the antifouling capability of EAR16-II coatings at a molecular level. The current work will pave the way to the development of novel coating materials to address the nonspecific protein adsorption on PDMS, thereby broadening the potential uses of PDMS-based microfluidic chips in complex biological analysis.
聚二甲基硅氧烷（PDMS）已成为微流控和生物应用中广泛使用的材料。然而，PDMS存在不可接受的高水平非特异性蛋白质吸附，这显著降低了基于PDMS的微流控芯片的性能。大多数现有的减少PDMS蛋白质污染的方法是通过表面氧化、聚合物接枝和物理吸附涂层使表面更具亲水性。这些方法存在稳定性相对较短、多步复杂处理程序或吸附减少不足的问题。在此，我们基于具有精心设计的氨基酸组成和序列的自组装肽开发了一种新颖且简便的修饰方法，该方法还能以与蛋白质相同的方式与PDMS表面强烈相互作用，用于抑制非特异性蛋白质污染并提高基于PDMS的微流控芯片的生物相容性。我们首先证明，一种离子互补肽EAR16-II，其序列为[(Ala-Glu-Ala-Glu-Ala-Arg-Ala-Arg)2]，在低浓度碳水化合物存在下，能在天然疏水和等离子体氧化的亲水性PDMS表面上轻松自组装成主要由紧密堆积的β-折叠组成的两亲性薄膜。自组装的EAR16-II两亲性薄膜将其疏水侧暴露于溶液中，从而使PDMS表面具有约110.0°的水接触角（WCA），呈现疏水性。然而，自组装的EAR16-II两亲性薄膜表现出优异的蛋白质排斥和血液相容性，与先前报道的方法相当或更好。已提出一个示意图模型来解释EAR16-II与PDMS表面的相互作用以及EAR16-II涂层在分子水平上的防污能力。当前的工作将为开发新型涂层材料以解决PDMS上的非特异性蛋白质吸附铺平道路，从而拓宽基于PDMS的微流控芯片在复杂生物分析中的潜在用途。
