Integrated Graphene Oxide Purification-Lateral Flow Test Strips (iGOP-LFTS) for Direct Detection of PCR Products with Enhanced Sensitivity and Specificity
Abstract
An integrated graphene oxide purification-lateral flow test strip (iGOP-LFTS) was developed for on-strip purifying and visually detecting polymerase chain reaction (PCR) products with an improved sensitivity as well as a more stringent specificity. PCR products amplified with a pair of biotin- and digoxin-labeled primers were directly pipetted onto GO pads, on which graphene oxide selectively adsorbed residual primers and primer-dimers with the aid of a running buffer containing MgCl2 and Tween 20. By stacking up three GO pads to increase the surface area for adsorption, 83.4% of double-stranded DNA with a length of 30 bp and 98.6% of 20-nt primers could be removed from a 10-μL DNA mixture. Since no primers interfered with detection, the increase of the sample loading volume from 5 to 20 μL could improve the signal-to-noise ratio of the test line 1.6 fold using the iGOP-LFTS while no changes were observed using the conventional LFTS. The limit of detection of the iGOP-LFTS was determined to be 30 copies of bacteriophage λ-DNA with naked eyes and this limit could be further decreased to 3 copies by loading 20 μL of the sample, which corresponded to a 1000-fold improvement compared to that of the LFTS detected by naked eyes. When...Continue Reading
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