Controllable droplet motion has attracted extensive attention but still faces the challenges of an uncontrollable sliding speed and a slow response rate. Here, controllable sliding speed and critical sliding angle (CSA) of a droplet on an oil-swollen organogel surface are achieved with a fast response rate via modulation of the DNA chain length. Comprehensive investigations ranging from macroscopic wetting behavior to molecular mechanism suggest that short single-stranded DNA (ssDNA) could act as a hydrotrope to interact with oil molecules via interfacial hydrophobic interactions while increasing the interfacial thickness and adhesion, thus hindering the movement of droplets. Conversely, long ssDNA generated from rolling-circle amplification tend toward a curled conformation, minimizing nucleobase exposure and leading to weak interfacial adhesion, allowing the droplets to slide easily. With a significant CSA gradient, biosensing applications for ATP, microRNA, and thrombin detection are demonstrated, indicating the potential for the detection of a broad range of targets.

可控的液滴运动引起了广泛的关注，但是仍然面临着无法控制的滑动速度和缓慢的响应速度的挑战。在这里，油溶胀的有机凝胶表面上的液滴的可控滑动速度和临界滑动角（CSA）通过DNA链长度的调节以快速响应速率实现。从宏观润湿行为到分子机理的全面研究表明，短的单链DNA（ssDNA）可以充当水溶助长剂，通过界面疏水相互作用与油分子相互作用，同时增加界面厚度和附着力，从而阻碍液滴的运动。相反，滚环扩增产生的长ssDNA趋向于卷曲的构象，从而使核碱基暴露最小化并导致较弱的界面黏附，使液滴易于滑动。借助显着的CSA梯度，证明了可用于ATP，microRNA和凝血酶检测的生物传感应用，这表明了检测多种靶标的潜力。