Figure 1.

(A) Schematic of the fluorescent-SERS dual-modal aptasensor for detection of MC-LR. MC-LR preferentially binds to aptamer of Cy3-cDNA/aptamer-GNS conjugates, leading to the dissociation of aptamer from and sticking of Cy3-cDNAs to the GNS surface. This enables fluorescence quenching and SERS enhancement of Cy3 dyes. Sequences of the MC-LR specific aptamers and Cy3-cDNA are also shown here. (B) (i) Calculated electric field (|E|²/|E₀|²) distribution of a single GNS excited at 785 nm; and (ii) the E-field enhancement as a function of the distance away from the GNS tip, marked with the green dot line in the panel (i).