Preparation of Ag-MOF based high-performance SERS substrate for the rapid detection of paraquat in plasma

Paraquat (PQ) is the herbicide that has been proven to be harmful to humans and poses significant risks. Rapid and accurate determination of PQ in clinical practice would aid in the correct diagnosis and timely treatment of patients with PQ poisoning. This study aims to utilize surface-enhanced Raman spectroscopy (SERS) for the rapid and accurate detection of PQ in human plasma. Ag nanoparticles modified metal-organic framework (Ag-MOF) was prepared by sodium citrate reduction method as SERS substrate. The octahedral NH₂-MIL-88B(Fe) was selected as the MOF matrix due to its porous structure and excellent adsorption capacity, which enabled the adsorbed PQ to be brought closer to the "hot spots" generated by the local surface plasmon resonance (LSPR) of Ag. Consequently, the Ag-MOF exhibited good PQ detection performance, with limits of detection (LOD) as low as 3.36 × 10^-9 M (0.86 μg/L) and 4.98 × 10^-9 M (1.28 μg/L) for aqueous solutions and human plasma samples, respectively. Furthermore, the prepared Ag-MOF SERS substrate demonstrated good selectivity, reproducibility, and stability, providing a simple, rapid, and sensitive method for detecting PQ in human plasma. It is expected to be applied in clinical PQ detection.