Label-free electrochemical immunosensor for insulin detection by high-efficiency synergy strategy of Pd NPs@3D MoSx towards H2O2.

Here, a novel H2O2-based electrochemical immunosensor utilizing Pd nanoparticles functionalized three-dimensional wrinkly amorphous MoSx composites (Pd NPs@3D MoSx) as the platform was developed for the determination of insulin. In this work, Pd NPs@3D MoSx prepared in the presence of CTAB possessed an excellent catalytic activity for the reduction of H2O2. Furthermore, Pd NPs@3D MoSx with favorable biological compatibility can conjugate a great many antibodies to capture insulin. Attributed to the excellent property, electrochemical signals could be greatly amplified, contributing to improving detection sensitivity. Especially, SEM, TEM, and XPS information further confirmed nanomaterial's surface morphology and amorphous structure. Under the optimal conditions, the proposed immunosensor exhibited a sensitively linear relation with logarithmic insulin concentrations from 0.01 to 100 ng/mL with a low detection limit of 3.0 pg/mL (S/N = 3). Characterized by good reproducibility, specificity, and stability, the fabricated immunosensor may blaze a path for insulin detection in a real sample.