Figure 2.

Raman spectra acquired on untreated substrates and aptamer-functionalized nanopillars. When nonspecific adsorption of vasopressin on the substrate surface occurs (no aptamers), signal is only obtained at very high concentrations (e.g., 10 μM TVP, green trace). At low concentrations (e.g., 10 nM TVP, yellow trace), the signal enhancement is very low, indicating that very few molecules actually reside close to a hotspot. On the other hand, when the pillars are functionalized with selective aptamers, the signal intensity greatly increases. Five possible diagnostic peaks with two of the most dominant Raman peaks (1370 and 1510 cm⁻¹) of TAMRA were observed during experiments with different analyte concentrations.