Sensor for fisetin based on gold nanoparticles in ionic liquid and binuclear nickel complex immobilized in silica

Abstract

Gold nanoparticles dispersed in an ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (Au-BMI.PF₆) and a binuclear nickel(II) complex ([Ni₂(HBPPAMFF)μ-(OAc)₂(H₂O)]BPh₄) immobilized on functionalized silica were successfully applied in the construction of a novel sensor for the determination of fisetin by square-wave voltammetry. Under optimized conditions, the analytical curve showed two linear ranges for fisetin concentrations from 0.28 to 1.39 μM and 2.77 to 19.50 μM with a detection limit of 0.05 μM. This sensor demonstrated suitable stability (ca. 150 days; at least 500 determinations) and good repeatability and reproducibility, with relative standard deviations of 2.91 and 5.11%, respectively. The recovery study of fisetin in apple juice samples gave values from 96.4 to 106.4%. The efficient analytical performance of the proposed sensor can be attributed to the effective immobilization of the Ni^IINi^II complex on silica and the Au-BMI.PF₆ contribution to the electrode response.