Highly catalysis amplification of MOFNd-loaded nanogold combined with specific aptamer SERS/RRS assay of trace glyphosate

Abstract

A neodymium metal–organic framework (MOF_Nd) was prepared using 1H-pyrazole-3,5-dicarboxylic acid (H₃pdc) and 2-pyrazinecarboxylic acid as ligands. Through the addition of HAuCl₄ as a precursor and NaBH₄ as a reducing agent, a new MOF_Nd-loaded nanogold (AuNPs) (Au@MOF_Nd) nanosol with good stability and high catalytic activity was conveniently prepared via a solvothermal-reduction method and characterized. It was found that the indicator reaction of reducing HAuCl₄ by Na₂SO₃ to generate AuNPs was slow. Au@MOF_Nd strongly catalyzes this nanoreaction, and the produced AuNPs exhibit a strong resonance Rayleigh scattering (RRS) peak at 370 nm, and a strong surface-enhanced Raman scattering (SERS) peak at 1617 cm⁻¹ with the addition of the molecular probe Victoria blue 4R (VB4r). A novel SERS/RRS di-mode quantitative analysis method for glyphosate (GLY) was established by coupling this new Au@MOF_Nd catalytic indicator reaction with the aptamer (Apt) reaction of GLY, with SERS and RRS detection limits of 0.02 nM and 0.3 nM, respectively. It has been applied to the analysis of soil samples with a recovery rate of 93.0%–106.5% and precision of 2.2%–4.1%, and the results were satisfactory.