Target-Responsive
DNA Hydrogel Mediated “Stop-Flow”
Microfluidic Paper-Based Analytic Device for Rapid, Portable and Visual
Detection of Multiple Targets
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Abstract
A versatile point-of-care assay platform
was developed for simultaneous
detection of multiple targets based on a microfluidic paper-based
analytic device (μPAD) 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 μPAD.
In the absence of a target, the hydrogel is formed in the flow channel,
stopping the flow in the μPAD 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 μPAD, 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 Pb<sup>2+</sup>, 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