Department of Chemistry and Biochemistry, Southern Illinois University, Carbondale, Illinois 62901, United States.
Department of Physics, Southern Illinois University, Carbondale, Illinois 62901, United States.
ACS Appl Mater Interfaces. 2020 Nov 18;12(46):52156-52165. doi: 10.1021/acsami.0c14912. Epub 2020 Nov 5.
Flexible and ultrasensitive biosensing platforms capable of detecting a large number of trinucleotide repeats (TNRs) are crucial for future technology development needed to combat a variety of genetic disorders. For example, trinucleotide CGG repeat expansions in the gene can cause Fragile X syndrome (FXS) and Fragile X-associated tremor/ataxia syndrome (FXTAS). Current state-of-the-art technologies to detect repeat sequences are expensive, while relying on complicated procedures, and prone to false negatives. We reasoned that two-dimensional (2D) molybdenum sulfide (MoS) surfaces may be useful for label-free electrochemical detection of CGG repeats due to its high affinity for guanine bases. Here, we developed a low-cost and sensitive wax-on-plastic electrochemical sensor using 2D MoS ink for the detection of CGG repeats. The ink containing few-layered MoS nanosheets was prepared and characterized using optical, electrical, electrochemical, and electron microscopic methods. The devices were characterized by electron microscopic and electrochemical methods. Repetitive CGG DNA was adsorbed on a MoS surface in a high cationic strength environment and the electrocatalytic current of the CGG/MoS interface was recorded using a soluble Fe(CN) redox probe by differential pulse voltammetry (DPV). The dynamic range for the detection of prehybridized duplexes ranged from 1 aM to 100 nM with a 3.0 aM limit of detection. A detection range of 100 fM to 1 nM was recorded for surface hybridization events. Using this method, we were able to observe selectivity of MoS for CGG repeats and distinguish nonpathogenic from disease-associated repeat lengths. The detection of CGG repeat sequences on inkjet printable 2D MoS surfaces is a forward step toward developing chip-based rapid and label-free sensors for the detection of repeat expansion sequences.
能够检测大量三核苷酸重复（TNR）的灵活和超灵敏生物传感平台对于未来对抗各种遗传疾病所需的技术发展至关重要。例如，基因中的三核苷酸 CGG 重复扩展会导致脆性 X 综合征（FXS）和脆性 X 相关震颤/共济失调综合征（FXTAS）。目前用于检测重复序列的最先进技术既昂贵，又依赖于复杂的程序，且容易出现假阴性。我们认为，二维（2D）硫化钼（MoS）表面由于其对鸟嘌呤碱基的高亲和力，可能有助于对 CGG 重复进行无标记电化学检测。在这里，我们使用 2D MoS 油墨开发了一种低成本且灵敏的蜡上塑料电化学传感器，用于检测 CGG 重复。油墨中含有几层 MoS 纳米片，使用光学、电学、电化学和电子显微镜方法进行了制备和表征。使用电子显微镜和电化学方法对器件进行了表征。在高阳离子强度环境中，重复的 CGG DNA 被吸附在 MoS 表面上，通过差分脉冲伏安法（DPV）使用可溶性 Fe(CN) 氧化还原探针记录 CGG/MoS 界面的电催化电流。预杂交双链体检测的动态范围从 1 aM 到 100 nM，检测限为 3.0 aM。表面杂交事件的检测范围记录为 100 fM 至 1 nM。使用该方法，我们能够观察到 MoS 对 CGG 重复的选择性，并区分非致病性和与疾病相关的重复长度。在喷墨可打印 2D MoS 表面上检测 CGG 重复序列是朝着开发基于芯片的快速和无标记传感器以检测重复扩展序列迈出的重要一步。
