Capillarity-driven Enrichment and Hydrodynamic Trapping of Trace Nucleic Acids by Plasmonic Cavity Membrane for Rapid and Sensitive Detections.

Small reactor-based Polymerase chain reaction (PCR) has attracted considerable attention. A significant number of tiny reactors must be prepared in parallel to capture, amplify and accurately quantify few target genes in clinically relevant large volume, which, however, requires sophisticated microfabrication and longer sample-to-answer time. Here we report single plasmonic cavity membrane that not only enriches and captures few nucleic acids by taking advantage of both capillarity and hydrodynamic trapping but also quickly amplifies them for sensitive plasmonic detection. We fabricate the plasmonic cavity membrane with few nanoliters in a void volume by self-assembling gold nanorods with SiO2 tips. Simulations reveal that hydrodynamic stagnation between the SiO2 tips is mainly responsible for the trapping of the nucleic acid in the membrane. Finally, we show that our plasmonic cavity membrane is capable of enriching SARS-CoV-2 genes up to 20000-fold within 1 min, amplifying within 3 min, and detecting the trace genes as low as a single copy per microliter. We anticipate that our work not only expands the utility of PCR but also provide an innovative way of the enrichment and detection of trace biomolecules in a variety of point-of-care testing applications. This article is protected by copyright. All rights reserved.