Au-modified metal-organic framework photonic heterostructure as a SERS sensor for enrichment and detection of trace organic dyes and pesticides

Surface enhanced Raman scattering (SERS) sensors with excellent sensitivity, stability and repeatability are essential for the ultrasensitive analysis of trace targets. In this study, a SERS sensor was developed using a photonic heterostructure composed of Au nanoparticles (AuNPs) & Zeolitic Imidazolate Framework-8 photonic crystals (ZIF-8 PCs). The sensor aims to enrich and detect organic dyes and pesticides, with enhanced detection capabilities achieved through adjustments in AuNPs content and the band-edge effects of ZIF-8 PCs. The sensor exhibited excellent performances in detecting 4-mercaptobenzoic acid. The detection limit was 1 × 10^–12 mol·L⁻¹, with a relative standard deviation of 5.0 % and the enhancement factor of 1.439 × 10¹¹. Furthermore, the self-enrichment function of the sensor was verified through molecular dynamics simulations. This validation enabled the SERS sensor to be effectively utilized for the analysis of Rhodamine 6 G (R6G), methylene blue (MB), Thiabendazole (TBZ) and Parathion-methyl (PTM) without complex pretreatment. The detection limits achieved were 1 × 10^–12 for R6G and MB, and 1 × 10^–11 mol·L⁻¹ for TBZ and PTM, respectively. This study presented an effective strategy for constructing high-performance SERS sensors, elucidated the mechanism of analyte enrichment and achieved the detection of samples in natural lake water, which offers a new option for on-site monitoring of contaminants with a portable Raman spectroscopy.