Fig. 2

Highly tunable morphology of P-GERTs. a Representative TEM images of P-GERTs as a function of incubation time (0.5, 2, 5, 10, 20, 30, 60, and 960 min, respectively) of Au core and Raman reporter 4-NBT. Red arrows indicate the internal nanogaps of P-GERTs. Presumed growth process of the Au shell on b low-density and c high-density 4-NBT decorated Au cores, with corresponding time-lapse TEM examinations. All scale bars are 20 nm. d Comparison of mean SERS intensity before and after 4-NBT molecules decoration on the external surface of P-GERTs with various morphologies excited by 785 nm (black) and 638 nm (red) laser. Error bars are standard deviations from three independent measurements. Source data are provided as a Source Data file