Low background dual-ligand Cu-MOF nanoprobe for plant tissue imaging and fast screening as well as sensitive detection of glyphosate in environmental samples

Abstract

The monitoring of glyphosate residual in environmental samples is critically important due to its high environmental risk. Here, we reported a low background dual-ligand and fast response copper-based metal organic framework (Cu-MOF) nanoprobe for imaging glyphosate in plant tissue, rapid screening of glyphosate-contaminated samples, and sensitive detection of glyphosate in environmental samples. The Cu-MOF nanoprobe was prepared with 2-Aminoisophthalic Acid (AIA) and trimesic acid (H₃BTC) as ligands, and Cu²⁺ as a metal node. Thanking to both ligand-to-metal charge transfer (LMCT) and photoinduced electron transfer (PET) effects, the fluorescence of ligand AIA could be fully quenched in Cu-AIA/BTC probe. Upon the addition of glyphosate, it competed with the ligands in Cu-AIA/BTC probe, causing the collapse of MOF structure and the release of ligand AIA with obvious fluorescence recovery. This nanoprobe exhibited a desirable linear response for glyphosate in the concentration range of 0.1-80 μM, with a low detection limit of 33 nM, much lower than the maximum contaminant level (4.1 μM) set by the U.S. Environmental Protection Agency (EPA). Furthermore, it was also successfully applied for plant tissue imaging, fast screening of glyphosate-contaminated samples and monitoring of the degradation of glyphosate on tea leaves and in soil, indicating the broad application prospect of the nanoprobe.