A novel fluorescence and naked eye sensor for iodide in urine based on the iodide induced oxidative etching and aggregation of Cu nanoclusters

We had developed a novel method for the detection of I− based on the polyethyleneimine (PEI) protected copper nanoclusters (Cu NCs) which was simple, fast, cheap, non-toxic, selective and sensitive. To the best of our knowledge, the Cu NCs for sensing I− had not been reported so far. The potential for naked eye detection for I− of the PEI-protected Cu NCs was also explored. Due to the unique reactions between PEI-protected Cu NCs and I−, a monolayer of CuI formed on the surface of PEI-protected Cu NCs, and then iodide-induced oxidative etching and aggregation produced the fluorescence quenching of PEI-protected Cu NCs which facilitated our sensing approach. Thus, this sensing system exhibited high selectivity toward I− over other of anions. The fluorescence intensity of PEI-protected Cu NCs was linearly proportional to I− over the concentration range from 0-10 μM with a correlation coefficient of 0.994, 10-100 μM with a correlation coefficient of 0.996, and 100-800 μM with a correlation coefficient of 0.995. The detection limit was 100 nM. This method was applied to the determination of I− in urine samples.