TbMOF@Au catalytic determination of trace malathion with aptamer SERS/RRS/Abs assay

Terbium metal-organic framework (TbMOF) was prepared by microwave method with 1,3,5-benzenetricarboxylic acid as ligand. With HAuCl₄ as precursor and NaBH₄ as reducing agent, TbMOF-loaded gold nanoparticles (AuNPs) catalyst (TbMOF@Au₁) was prepared rapidly and characterized by transmission electron microscope (TEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. It was found that TbMOF@Au₁ has a strong catalytic effect on the HAuCl₄-Cys nanoreaction, and the produced AuNPs have a strong resonant Rayleigh scattering (RRS) peak and surface plasmon resonance absorption (Abs) peak at 370 nm and 550 nm, respectively. With the addition of the molecular probe Victoria blue 4R (VB4r), AuNPs have a strong surface-enhanced Raman scattering (SERS) effect, the target analyte molecules are trapped in between the nanoparticles and a hot spot effect created in the process resulting in an extremely high SERS signal. A new SERS/RRS/Abs triple-mode analysis method for Malathion (MAL) was established by coupling this new TbMOF@Au₁ catalytic indicator reaction with MAL aptamer (Apt) reaction, and its SERS detection limit was 0.21 ng/mL. The SERS quantitative analysis method has been applied to the analysis of fruit samples with the recovery of 92.6-106.6 % and the precision of 2.72-8.16 %.