Fig. 1.

Schematic illustration for the quantitative evaluation of influenza A/H1N1 and SARS-CoV-2 using the dual-mode SERS aptasensor. (a) Two Raman reporters-labeled DNA aptamers are hybridized with capture DNAs on the Au nanopopcorn substrate. The internal standard 4-MBAs are immobilized along with aptamer DNAs on the Au nanopopcorn substrate. Recognition of target protein induces the aptamer’s conformational change, leading to decreased corresponding Raman signal intensities for (b) SARS-CoV-2, 0 PFU/mL (black) to 1000 PFU/mL (red) and (c) Influenza A/H1N1, 0 HAU/mL (black) to 403 HAU/mL(red).