Institute of Nano- and Biotechnologies, FH Aachen, Campus Jülich, 52428 Jülich, Germany; Institute of Pharmaceutical Chemistry, Philipps University Marburg, 35037 Marburg, Germany.
Institute of Nano- and Biotechnologies, FH Aachen, Campus Jülich, 52428 Jülich, Germany; Institute of Complex Systems Bioelectronics (ICS-8), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.
Biosens Bioelectron. 2019 Feb 1;126:510-517. doi: 10.1016/j.bios.2018.11.019. Epub 2018 Nov 15.
The reusability of capacitive field-effect electrolyte-insulator-semiconductor (EIS) sensors modified with a cationic weak polyelectrolyte (poly(allylamine hydrochloride) (PAH)) for the label-free electrical detection of single-stranded DNA (ssDNA), in-solution- and on-chip-hybridized double-stranded DNA (dsDNA) has been studied. It has been demonstrated that via simply regeneration of the gate surface of the EIS sensor by means of an electrostatic adsorption of a new PAH layer, the same biosensor can be reused for at least five DNA-detection measurements. Because of the reversal of the charge sign of the outermost layer after each surface modification with the cationic PAH or negatively charged DNA molecules, the EIS-biosensor signal exhibits a zigzag-like behavior. The amplitude of the signal changes has a tendency to decrease with increasing number of macromolecular layers. The direction of the EIS-signal shifts can serve as an indicator for a successful DNA-immobilization or -hybridization process. In addition, we observed that the EIS-signal changes induced by each surface-modification step (PAH adsorption, immobilization of ssDNA or dsDNA molecules and on-chip hybridization of complementary target cDNA) is decreased with increasing the ionic strength of the measurement solution, due to the more efficient macromolecular charge-screening by counter ions. The results of field-effect experiments were supported by fluorescence-intensity measurements of the PAH- or DNA-modified EIS surface using various fluorescence dyes.
已研究了带正电荷的弱聚电解质（聚烯丙基盐酸盐（PAH））修饰的电容场效应电解质-绝缘体-半导体（EIS）传感器的可重复使用性，用于无标记电检测单链 DNA（ssDNA），溶液中和芯片上杂交的双链 DNA（dsDNA）。已经证明，通过静电吸附新的 PAH 层来简单地再生 EIS 传感器的栅极表面，相同的生物传感器可以至少重复使用五次 DNA 检测测量。由于在每次用阳离子 PAH 或带负电荷的 DNA 分子进行表面修饰后，最外层的电荷符号都发生反转，因此 EIS-生物传感器信号呈现出锯齿状行为。信号变化的幅度随着大分子层数量的增加而有减小的趋势。EIS 信号的方向变化可以作为成功的 DNA 固定或杂交过程的指示。此外，我们观察到，由于测量溶液中的离子强度增加会导致抗衡离子更有效地屏蔽大分子电荷，因此每个表面修饰步骤（PAH 吸附、ssDNA 或 dsDNA 分子的固定以及互补靶 cDNA 的芯片杂交）引起的 EIS 信号变化都会减小。场效应实验的结果得到了使用各种荧光染料对 PAH 或 DNA 修饰的 EIS 表面进行荧光强度测量的支持。
