Enhanced broadband fluorescence detection of nucleic acids using multipolar gap-plasmons on biomimetic Au metasurfaces. Issue 29 (29th May 2019)

• Record Type: Journal Article
• Authors: Narasimhan, Vinayak; Siddique, Radwanul Hasan; Hoffmann, Magnus; Kumar, Shailabh; Choo, Hyuck
• Is Part Of: Nanoscale. Volume 11:Issue 29(2019)
• Page Start: 13750
• Page End: 13757
• Publication Date: 2019-05-29
• Subjects: Nanoscience -- Periodicals; Nanotechnology -- Periodicals; 620.505
• DOI: 10.1039/c9nr03178b
• Languages: English
• ISSNs: 2040-3364

Abstract

Abstract : Metasurfaces fabricated through a simple and scalable biomimetic technique are used to detect nucleic acids through gap-plasmon-enhanced broadband fluorescence. Abstract : Recent studies on metal–insulator–metal-based plasmonic antennas have shown that emitters could couple with higher-order gap-plasmon modes in sub-10-nm gaps to overcome quenching. However, these gaps are often physically inaccessible for functionalization and are not scalably manufacturable. Here, using a simple biomimetic batch-fabrication, a plasmonic metasurface is created consisting of closely-coupled nanodisks and nanoholes in a metal–insulator–metal arrangement. The quadrupolar mode of this system exhibits strong broadband resonance in the visible-near-infrared regime with minimal absorptive losses and effectively supresses quenching, making it highly suitable for broadband plasmon-enhanced fluorescence. Functionalizing the accessible insulator nanogap, analytes are selectively immobilized onto the plasmonic hotspot enabling highly-localized detection. Sensing the streptavidin–biotin complex, a 91-, 288-, 403- and 501-fold fluorescence enhancement is observed for Alexa Fluor 555, 647, 750 and 790, respectively. Finally, the detection of single-stranded DNA ( gag, CD4 and CCR5 ) analogues of genes studied in the pathogenesis of HIV-1 between 10 pM–10 μM concentrations and then CD4 mRNA in the lysate of transiently-transfected cells with a 5.4-fold increase in fluorescence intensity relative to an untransfected control is demonstrated. This outcome promises the use of biomimetic Au metasurfaces as platforms for robust detection of low-abundance nucleic acids.