Gold-silver core-shell nanoparticle-based impedimetric immunosensor for detection of iron homeostasis biomarker hepcidin.

An impedimetric immunosensor based on gold-silver core-shell nanoparticles for hepcidin detection is reported. The core-shell nanoparticles were prepared by seed-mediated method and characterized by dynamic light scattering, UV-Vis, XRD, field emission-scanning electron micrograph imaging, energy dispersive spectroscopy, and atomic force microscopy. The immunosensor was fabricated with core-shell nanoparticles and cysteamine employing covalent chemistry (amide bond formation) strategy for ensuring proper orientation of anti-hepcidin antibody on to the amine-functionalized nanomaterial decorated electrodes. The hepcidin detection principle was based on the variation of charge transfer resistance (ΔR) relative to the Fe(CN) electrochemical probe in the presence of the biomarker. The frequency range was 10 to 10 Hz at the scan rate of 10 mV sand a potential of 0.1 V. Based on the antigen-antibody interaction in 40 min at pH 7.0, a linear relationship between ΔR and hepcidin concentration was obtained in the range 0.01 to 100 ng/mL with a detection limit of 0.857 pg/mL. Furthermore, the designed immunosensor had acceptable reproducibility, stability, selectivity, and reusability. It was successfully applied to the detection of hepcidin in spiked human serum samples and acceptable recovery (90-95.9%) was obtained. Graphical abstract Gold-silver core-shell nanoparticle-based impedimetric immunosensor for detection of iron homeostasis biomarker hepcidin. The study focuses on the detection of iron regulatory protein hepcidin using gold-silver core-shell nanoparticles. This immunosensor was fabricated with core-shell nanoparticles and cysteamine employing covalent chemistry (amide bond formation) strategy. The sensor was sensitive in the range from 0.01 to 100 ng/mL, with a detection limit of 0.857 pg/mL.