Eu-Coordinated semiconducting polymer nanoparticles as a novel nanoprobe with two detection method signals for determination of copper(II) ions

Abstract Eu-coordinated semiconducting polymer nanoparticles (SPNs-Eu) were developed for bimodal analysis of copper(II) ions (Cu2+) over a wide dynamic range (μM to pM). In this sensing system, the first readout mode is based on the fluorescence signal of SPNs-Eu. A significant quenching of the fluorophore is selective for the presence of Cu2+ due to the aggregation of SPNs-Eu. The aggregations are caused by chelation of Cu2+ with carboxylate groups on SPNs-Eu and the amount of aggregation can be quantified by the 153Eu signal of SPNs-Eu using single-particle inductively coupled plasma mass spectrometry (sp-ICPMS). This signal is the second readout mode of these nanoparticles, which can be calibrated for sub-pM determination of Cu2+. Compared with the monodisperse SPNs-Eu reagent, aggregation in the presence of Cu2+ significantly decreases the number of detected particles or particle clusters within a sampling period of the sp-ICPMS measurement. The fluorescence readout yields a facile and rapid detection method with a rather limited linear range from 2 μM to 50 μM and a limit of detection (LOD) of 0.29 μM. In contrast, the sp-ICPMS readout provides a far more sensitive analysis method with a linear range from 1 pM to 10 μM and a LOD of 0.42 pM.