Folding-based electrochemical sensors employing electrode-immobilized, structure-switching aptamers represent a promising platform for rapid and selective detection of a variety of target analytes. Sensitivity of this class of sensors usually needs, however, to be improved through re-engineering the parent aptamer probes to undergo large conformation change upon target binding. Here, we report the development of a sensitive folding-based electrochemical sensor for tobramycin by re-engineering a DNA hairpin aptamer based on the concept of intrinsic disorder. Through incorporating disordered poly-thymine base spacers of various lengths into the loop of the parent hairpin aptamer, structure-switching aptamers exhibiting large target binding-induced conformation change for high signal sensitivity were re-engineered and an optimal hairpin aptamer containing a disordered spacer of 24 thymine bases (probe T) was obtained. Folding-based electrochemical sensor modified with the probe T is sensitive for tobramycin with a maximum percent signal change of 767.1% for signal-saturating target concentration compared to 54.7% obtained using the parent aptamer. This sensor is also selective enough and applicable to detection of tobramycin in real samples with satisfactory results. We believe that the intrinsic disorder-based concept for re-engineering of structure-switching aptamers will help guide further design and application of highly sensitive aptamer folding-based electrochemical sensors.

中文翻译：

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利用内在无序机制合理设计发夹适体以提高基于适体折叠的妥布霉素电化学传感器的灵敏度


采用电极固定、结构转换适体的基于折叠的电化学传感器代表了快速、选择性检测各种目标分析物的有前景的平台。然而，此类传感器的灵敏度通常需要通过重新设计亲本适体探针以在靶标结合时经历较大的构象变化来提高。在这里，我们报告了通过基于内在无序概念重新设计 DNA 发夹适体，开发了一种敏感的基于折叠的妥布霉素电化学传感器。通过将不同长度的无序多聚胸腺嘧啶碱基间隔区合并到亲本发夹适体的环中，重新设计了具有大靶点结合诱导构象变化以实现高信号灵敏度的结构转换适体，并获得了包含无序间隔区的最佳发夹适体获得24个胸腺嘧啶碱基（探针T）。用探针 T 修饰的基于折叠的电化学传感器对妥布霉素敏感，信号饱和目标浓度的最大信号变化百分比为 767.1%，而使用亲本适体获得的信号变化百分比为 54.7%。该传感器也具有足够的选择性，适用于实际样品中妥布霉素的检测，结果令人满意。我们相信，基于内在无序的结构转换适体再设计概念将有助于指导高灵敏度适体折叠电化学传感器的进一步设计和应用。