Target-Responsive DNA Hydrogel Mediated Stop-Flow Microfluidic Paper-Based Analytic Device for Rapid, Portable and Visual Detection of Multiple Targets

A versatile point-of-care assay platform was developed for simultaneous detection of multiple targets based on a microfluidic paper-based analytic device (mu PAD) using a target-responsive hydrogel to mediate fluidic flow and signal readout. An aptamer-cross-linked hydrogel was used as a target-responsive flow regulator in the mu PAD. In the absence of a target, the hydrogel is formed in the flow channel, stopping the flow in the mu PAD and preventing the colored indicator from traveling to the final observation spot, thus yielding a signal off readout. In contrast, in the presence of a target, no hydrogel is formed because of the preferential interaction of target and aptamer. This allows free fluidic flow in the mu PAD, carrying the indicator to the observation spot and producing a signal on readout. The device is inexpensive to fabricate, easy to use, and disposable after detection. Testing results can be obtained within 6 min by the naked eye via a simple loading operation without the need for any auxiliary equipment. Multiple targets, including cocaine, adenosine, and Pb2+, can be detected simultaneously, even in complex biological matrices such as urine. The reported method offers simple, low cost, rapid, user-friendly, point-of-care testing, which will be useful in many applications.