Magnetic Control-Enhanced Lateral Flow Technique for Ultrasensitive Nucleic Acid Target Detection

In this work, a lateral flow (LF)-based detection strategy termed magnetic control-enhanced LFA (MCLF) was proposed to detect nucleic acid sequences at attomolar sensitivity. In the proposed MCLF method, magnetic controllers which are magnetic nanoparticles modified with antibodies against the labels on capture sequences were used to interact with the unreacted labeled capture sequence (CS-label) to improve the detection limit. By regulating the movement of magnetic probes (magnetic controllers) with a simple magnet under the lateral flow strip, the movement of magnetic probes bounded with unreacted CS-label in the sample flow could be reduced. Therefore, the target sequence-containing sandwich structures will arrive at the test zone prior, to interact with the recognition ligands, whereby the capture efficiency of the sandwich structures could be increased because the unreacted capture sequences at the test zone will be reduced. With the colorimetric signal from gold nanoparticle-based probes, the proposed MCLF technique could recognize as low as 100 aM of DNA target sequences by naked eyes, and the responding range of MCLF is from 100 aM to 10 pM.