Detection of ultra-trace levels of insulin by Fe3O4@MoS2/rGO-GCE as a sensor based on isoelectric points

A transition metal dichalcogenide (TMD) composite consisted of MoS2 coated magnetite nanoparticles, hybridized with reduced graphene oxide, loaded on the surface of a glassy carbon electrode (Fe3O4@MoS2/rGO-GCE) was applied for detection of trace amounts of in vitro insulin based on isoelectric points of the modifier and the insulin. The nanocomposite was characterized by X-ray diffraction (XRD), energy dispersive X-Ray analysis (EDX), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Differential pulse voltammetry (DPV) was applied for quantitative analysis of insulin and a wide linear range of insulin concentration (10-1800nM) was obtained along with good linearity (r(2)=0.992), significant limit of detection (5.4nM) and grate reproducibility (RSD%=2.03). Based on our knowledge, it is the first report for detection of insulin as a bio-macromolecule in partnership with a composite of transition metal dichalcogenides.