Ultrasensitive SERS detection of trace polycyclic aromatic hydrocarbons in seawater using 1-propanethiol modified Fe3O4/Ag@inositol hexaphosphate nanocomposite

Polycyclic aromatic hydrocarbons (PAHs) in seawater even at trace level could continuously cause serious threats via food chain. Herein, we fabricate 1-propanethiol (C3)-modified Ag@inositol hexaphosphate (IP6)-decorated Fe3O4 composite nanomaterials, namely Fe3O4/Ag@IP6-C3. The magnetic and hydrophobic of Fe3O4/Ag@IP6-C3 could greatly enrich PAHs molecules and has giant surface enhanced Raman scattering (SERS) effect due to magnetic inducing increase of SERS “hot spots”. The optimized SERS effect of Fe3O4/Ag@IP6-C3 triggered by the spatial distributions of electromagnetic field were validated by using finite difference time domain (FDTD) calculations, and the enhancement factor (EF) of 1.26 × 107 for 4-mercaptopyridine (4-MPy) as Raman probe. Interestingly, Fe3O4/Ag@IP6-C3-based SERS protocol shows specific response to pyrene owing to the great partitioning to pyrene in the presence of C3, which is also proofed by the simulation of binding energies between PAH molecules and Ag@IP6-C3 by using DFT method. The quantitative linear range for the detection of pyrene is from 1 μg/L to 10 mg/L (R2 =0.989) and the limit of detection (LOD) of 24 ng/L (24 ppt) is reached, which meets the limitation amount (1 ppb) of PAHs in water set by USEPA and WHO. Clearly, as-proposed SERS sensing strategy paves a path to realize seashore monitoring of marine environmental and early warning for PAHs pollution based on the pyrene as an indicator.