Figure 5.

Schematic illustration of dual AuNP-assisted signal amplification for detection of exosomes. First, the Au film was functionalized with capture DNA and the target exosomes were detected by direct measurement. Next, aptamer/T₃₀-linked AuNPs were added, and target exosomes were detected by a single AuNP-amplified SPR aptasensor. Finally, A₃₀-coated AuNPs could be captured on the aptamer/T₃₀-linked AuNPs through the hybridization of two complementary sequences of T₃₀ and A₃₀. The target exosomes were detected by dual AuNP-amplified SPR aptasensor (adapted from Wang et al.).⁵⁵