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.
J Mater Chem B. 2019 Apr 14;7(14):2242-2246. doi: 10.1039/c9tb00084d. Epub 2019 Feb 28.
The existence of nonspecific protein adsorption often results in significant challenges for microfluidic devices and laboratory cultureware used in biological experiments. Developing antifouling surfaces is thus increasingly desired by microfluidics engineers and biologists. Our previous studies have demonstrated that ionic hydrogen bonding between free ε-NH groups of the alkaline amino acids in proteins and surface negatively charged groups plays a critical role in strong adsorption of proteins onto the solid surfaces. Thus, the current work presents a facile and universal surface modification method based on self-assembly of oligopeptides with a sequence of Ala-Lys-Ala-Lys-Ala-Lys-Ala-Lys (AK-VIII) on poly(dimethylsiloxane) (PDMS) and polystyrene (PS) surfaces under physiological pH conditions. The results show that AK-VIII can self-organize into a compact amphipathic β-sheet-rich coating layer on the PDMS and PS surfaces with similar coverage, which largely minimizes nonspecific adsorption of proteins. In addition, we compared the performances of BSA and AK-VIII used as blocking reagents to evaluate their inhibitory effect on nonspecific adsorption of the antigen and detection antibody in carcinoembryonic antigen (CEA) enzyme-linked immunosorbent assay (ELISA). The results showed that AK-VIII exhibits better performance than BSA for diminishing nonspecific adsorption of the antigen and detection antibody, thus providing lower background noise, a lower detection limit, and a wider linear range in CEA assays. This study provides a novel and versatile alternative for developing antifouling coatings to address nonspecific protein adsorption on both PDMS-based engineering and PS-based biological materials.
非特异性蛋白质吸附的存在常常给微流控器件和生物实验用的实验室培养器皿带来重大挑战。因此，微流控工程师和生物学家越来越希望开发出具有抗污染表面的器件和器皿。我们之前的研究表明，蛋白质中碱性氨基酸的游离 ε-NH 基团与表面带负电荷基团之间的离子氢键在蛋白质强烈吸附到固体表面中起着关键作用。因此，目前的工作提出了一种基于在生理 pH 条件下自组装具有 Ala-Lys-Ala-Lys-Ala-Lys-Ala-Lys-Ala (AK-VIII) 序列的短肽的简便且通用的表面修饰方法，用于聚二甲基硅氧烷 (PDMS) 和聚苯乙烯 (PS) 表面。结果表明，AK-VIII 可以在 PDMS 和 PS 表面上自组织成具有相似覆盖率的紧密的两亲性 β-折叠丰富的涂层，这极大地最小化了蛋白质的非特异性吸附。此外，我们比较了 BSA 和 AK-VIII 作为封闭试剂的性能，以评估它们对癌胚抗原 (CEA) 酶联免疫吸附测定 (ELISA) 中抗原和检测抗体的非特异性吸附的抑制作用。结果表明，AK-VIII 比 BSA 更能减少抗原和检测抗体的非特异性吸附，从而在 CEA 测定中提供更低的背景噪声、更低的检测限和更宽的线性范围。这项研究为开发抗污染涂层提供了一种新颖而通用的替代方法，以解决 PDMS 基工程和 PS 基生物材料上的非特异性蛋白质吸附问题。
