Current visual biosensing methods, including colorimetric-based, fluorescence-based and chemiluminescence-based methods, are inappropriate for the hundreds of millions of people affected by color blindness and color weakness. Compared with these available methods, a droplet motion-based strategy might be a promising protocol for extension to a wider user base. Here we report a protocol for manipulating the hydrophobicity of DNA, which offers a droplet motion-based biosensing platform for the visual detection of small molecules (ATP), nucleic acids (microRNA) and proteins (thrombin). The protocol starts with target-triggered rolling-circle amplification that can readily generate short single-stranded DNA (ssDNA) fragments or long ssDNA. By exploiting macroscopic wetting behavior and molecular interaction, one can tailor the conformation of ssDNA on the water–oil interface to control the relevant DNA hydrophobicity. The wettability of DNA can be translated into visual signals via reading the sliding speed or the critical sliding angle. The time range for the entire protocol is ∼1 d, and the detection process takes ∼1 min.

当前的视觉生物传感方法，包括基于比色、基于荧光和基于化学发光的方法，不适用于数亿受色盲和色弱影响的人。与这些可用的方法相比，基于液滴运动的策略可能是一种有前途的协议，可以扩展到更广泛的用户群。在这里，我们报告了一种操纵 DNA 疏水性的协议，它提供了一个基于液滴运动的生物传感平台，用于小分子 (ATP)、核酸 (microRNA) 和蛋白质 (凝血酶) 的视觉检测。该协议从目标触发的滚环扩增开始，可以很容易地生成短的单链 DNA (ssDNA) 片段或长的 ssDNA。通过利用宏观润湿行为和分子相互作用，人们可以在水-油界面上调整 ssDNA 的构象，以控制相关的 DNA 疏水性。通过读取滑动速度或临界滑动角，可以将 DNA 的润湿性转化为视觉信号。整个协议的时间范围是∼ 1 d，检测过程耗时∼ 1 min。