An enzyme-free electrochemiluminescence insulin probe based on the regular attachment of ZnO nanoparticles on a 3-D nickel foam and H2O2 as an efficient co-reactant

Abstract

In this study, a highly sensitive, fast, and enzyme-free electrochemiluminescence (ECL) probe based on the decoration of zinc oxide nanoparticles on nickel foam is proposed for insulin determination. A silica film was employed as a size adjusting agent for the modification of the nickel foam surface with ZnO nanoparticles (ZnO NPs). The ECL of the ZnO NP/Ni foam was investigated in a natural medium in the presence of hydrogen peroxide (H₂O₂) as an efficient co-reactant. With increasing insulin concentration, a remarkable improvement in ECL signal was observed, which proved the enhancing effect of insulin on the ECL emission. The characterization of the ZnO-NP/Ni-foam electrode was performed via electrochemical impedance spectroscopy, Brunauer–Emmett–Teller (BET) surface area measurement, X-ray diffraction, field emission scanning electron microscopy (FESEM), and energy-dispersive X-ray analysis techniques. The fabricated electrode was applied for the trace analysis of insulin using the ultrasensitive ECL method in a phosphate buffer solution. Under the optimal conditions, the results showed excellent performance during insulin determination with a wide linear range of 3.57 × 10⁻¹⁵ M to 2.94 × 10⁻⁹ M, a low detection limit of 1.00 × 10⁻¹⁶ M, and a relative standard deviation of 1.03%. The proposed ECL sensor with excellent reproducibility, long-term stability, and high selectivity was used for insulin determination in real serum samples with acceptable outcomes.