Fig. 1.

Schematic diagram of sample preparation, data collection, and Au NS elemental analysis. (A) Schematic diagram illustrating the PAH extraction from human placental tissue and the Au NS-based SERS-SEIRA substrate used for PAHs/PACs detection. (B) A HAADF microscopy image displays a core-shell structure consisting of a 120 nm silica core surrounded by an approximately 15 nm thick gold shell. Elemental mapping images showing the distribution of gold (yellow), silica (cyan), and oxygen (red), along with a composite image integrating all elements. (C) Darkfield image of the NS, with an Inset showing the size distribution, (D) elemental map distribution, and (E) EDX analysis.