Scheme 1. (A) Schematic illustration of the dynamic SERS platform Au@4-Mpy@AgNPs for quantitative analysis. (B and E) The 3D hotspot matrix SERS platform was constructed in water ((a) the water-dispersed drying film system) or in water with the assistance of 2.5% v/v glycerol ((b) the glycerol-assisted liquid film protection system). (C and F) Schematic of the dynamic evolutions of signal intensity of IS and target molecules from (a) or (b) process, respectively, with the signal intensity plotted as a function of the evaporation time of the droplet.^30,31 (D and G) Typical SERS spectra of IS and target molecules from (a) or (b) process, respectively. CV was chosen as the model target molecule.