Ion-imprinted CDs-Pc nanohybrid sensor for ratiometric fluorescence and electrochemical detection of Pd(II)

We report here for the first time a novel dual-fluorescence emission and electrometric sensor based on palladium ion-imprinted organosiloxane nanoparticles (Pd-imp@CDs-Pc) grafted with both carbon dots (CDs) and phthalocyanine (Pc) dye for the determination of palladium ion, Pd(II) as a target. Nanoparticles showed two emission peaks at the double excitation wavelengths of 367 and 620 nm. These peaks were assigned to emissions induced by CDs (456 nm) and Pc (698 nm). The fluorescence of Pc embedded in nanoparticles is slightly quenched, whereas the emission from CDs is distinctly quenched by Pd(II). On the other hand, Glassy Carbon Electrode (GCE), which was modified by using Pd-imp@CDs-Pc nanoparticles, displayed a sensitive electrochemical signal upon interaction with Pd(II). The reduction in emission intensity and peak current increase are both more pronounced for Pd-imp@CDs-Pc than for N-imp@CDs-Pc, which was synthesized in the absence of Pd(II), revealing a selective recognition ability of the Pd-imp@CDs-Pc. The emission ratio of fluorescence obtained at two wavelengths (F₄₅₆/F₆₉₈) diminished and peak current increased with the increase in Pd(II) concentration in the range of 2.7–90.4 µM and 5.6–390 nM, respectively. The limits of detection (LOD) for determining Pd(II) based on ratiometric fluorescence and electrochemical measurements were found to be 0.19 µM and 2.76 nM, respectively. The nanohybrid sensor exhibited also good selectivity to Pd(II) over other interfering metal ions. Fluorescence and electrochemical experimental results confirmed that the sensor based on Pd-imp@CDs-Pc nanoparticles was distinctively responsive and selective for determining Pd(II) in tap water and artificial seawater samples.