Department of Chemistry & Biochemistry, 1245 Lincoln Dr, Southern Illinois University at Carbondale, IL 62901, USA.
Department of Chemistry, University of Illinois at Urbana-Champaign, IL 61801, USA.
J Mater Chem B. 2020 Jun 24;8(24):5225-5233. doi: 10.1039/d0tb00507j.
Trinucleotide repeat (TNR) sequences widely exist in nature and their overgrowth is associated with two dozen neurodegenerative diseases in humans. These sequences have a unique helical flexibility, which affects their biophysical properties. A number of biophysical properties of these sequences have been studied in the past except their surface-tethered monolayers. To address the effect of sequence context and the associated helical flexibility on TNR monolayers, disease-relevant TNRs from three flexibility groups were surface-assembled on gold surfaces. The properties of the TNR films were studied, including charge transfer resistance (Rct) by electrochemical impedance spectroscopy (EIS), surface density by chronocoulometry (CC), surface topography by atomic force microscopy (AFM), and electrical conductivity by conducting atomic force microscopy (C-AFM). We found that the TNR film properties are characteristically sequence dependent rather than being dependent on their flexibility rank reported in the literature. The characteristic properties of TNR films studied here may be used for engineering label-free biosensors to detect neurological disorders and build DNA bioelectronics.
三核苷酸重复（TNR）序列广泛存在于自然界中，其过度生长与人类的二十几种神经退行性疾病有关。这些序列具有独特的螺旋灵活性，这影响了它们的物理性质。过去已经研究了这些序列的许多物理性质，除了它们的表面束缚单层。为了解决序列上下文和相关螺旋灵活性对 TNR 单层的影响，将来自三个灵活性组的与疾病相关的 TNR 序列通过表面组装在金表面上。研究了 TNR 薄膜的性质，包括电化学阻抗谱（EIS）的电荷转移电阻（Rct）、计时库仑法（CC）的表面密度、原子力显微镜（AFM）的表面形貌和导电原子力显微镜（C-AFM）的电导率。我们发现，TNR 薄膜的性质是特征性地依赖于序列，而不是依赖于文献中报道的它们的灵活性等级。这里研究的 TNR 薄膜的特征性质可用于工程无标记生物传感器来检测神经紊乱并构建 DNA 生物电子学。
