Fabrication of large-scale gold nanoplate films as highly active SERS substrates for label-free DNA detection

We introduce a simple but robust label-free method to detect DNA based on large-scale gold nanoplate (GNP) films with tunable localized surface plasmon resonance (LSPR) and highly surface-enhanced Raman scattering (SERS) activity. The common probe molecule, Neil Blue A sulfate (NBA) is used for testing the SERS activity of the GNP films at very low concentrations. It is found that the SERS properties are highly dependent on the edge lengths of gold nanoplate and gold nanoplate density in the films. Multiple-layer GNP films which are constructed by gold nanoplate with an edge length of 134±6 nm have the density of 916±40 GNPsGNPs/spot. It shows the highest signal intensity with SERS enhancement factor (EF) as high as 5.4×107 and also has excellent stability, reproducibility and repeatability. The optimized SERS-active substrate with the largest enhancement ability could be used to detect double-strand DNA without a dye label, and the detection limit is down to 10−6 mg/mL.

► We developed a simple, fast, and low-cost method to fabricate large-scale gold nanoplate films with tunable localized surface plasmon resonance (LSPR) and surface-enhanced Raman scattering (SERS) activity.
► Controlling the edge lengths of gold nanoplate and gold nanoplate density in the films could result in an optimized substrate with the greatest Raman enhancement.
► The multiple-layer GNP film constructed by gold nanoplates with edge length of 134 ± 6 nm show the highest signal intensity with SERS enhancement factor (EF) as high as 5.4×107.
► The optimized SERS-active substrate with the largest enhancement ability could be used to detect double-strand DNA without a dye label, and the detection limit is down to 10-6 mg/mL.