Dual-responsive electrochemical immunosensor for detection of insulin based on dual-functional zinc silicate spheres-palladium nanoparticles

In this study, described an electrochemical immunoassay for insulin that is based on the use of zinc silicate spheres loaded with palladium nanoparticles (Zn 2 SiO 4 -PdNPs) that act as dual-function labels. The Zn 2 SiO 4 -PdNPs display high electrocatalytic activity towards the reduction of H 2 O 2 and high sensitivity in chronoamperometry . The Zn 2 SiO 4 -PdNPs decrease the electron transfer rate between the electrolyte and the surface of the electrode, which can increase the changed current and enhance the sensitivity of the immunosensor as detected by square wave voltammetry (SWV). Electrodeposited gold is used as the matrix material. The icosahedral gold nanocrystals are coated with the primary antibodies formed a 3D mode to against abundant of insulin. Under optimal conditions, the assay has a linear response in the 0.1   pg   mL −1 to 50   ng   mL −1 insulin concentration range, and the limit of detection of the SWV and CA methods are 0.25 fg mL −1 and 80 fg mL −1 , respectively. Moreover, the immunosensor holds an outstanding analytical performance for the insulin detection and has promising potential in clinical diagnosis.