A highly selective SERS chip for rapid detection of copper ions in aquatic system

Abnormal amount of Cu2+ intake from foods and environment would interfere with cellular homeostasis and even trigger oxidative damage, cardiovascular disorders, severe neurodegenerative disorders, and cancer. In this work, a rapid surface enhanced Raman scattering (SERS) assay for picomolar copper ions (Cu2+) is developed based on the click reaction of Cu+-catalyzed alkyne azide cycloaddition (CuAAC). ITO supported 1,4-diethynyl-benzene (DEB) modified silver-coated gold nanoparticles is prepared as a two-dimension SERS platform (designated as ITO-Ag-co-Au-DEB), and the other terminal alkyne (-C---C-) of DEB exposes to provide the CuAAC reactive site. The generated click reaction product (1-benzyl-4-(4-ethynylphenyl)-1 H-1,2,3-triazole) contrib-utes to "turn on" SERS response, showing high detection sensitivity and selectivity. Furthermore, density func-tional theory (DFT) simulation is used to deepen understanding of sensing mechanism. Under optimal conditions, a linear range of concentrations from 6.35 ng/L to 6.35 mg/L and a detection limit of 33.45 pg/L for Cu2+ can be achieved. The SERS method based on the ITO-Ag-co-Au-DEB-click reaction is free from interference from co-existing metal ions in the aquatic system sample. Such a SERS strategy paves a novel route for continuous assessment of water quality safety in onshore and offshore water treatment systems.