Application of three-dimensional flower-like nanomaterials in the fabrication of sandwich-type electrochemical immunosensors

A novel and ultrasensitive sandwich-type electrochemical immunosensor was developed for the quantitative detection of carcinoembryonic antigen (CEA) in this work. Three-dimensional (3D) ZnO nanoflowers (NFs) were 3-aminopropyl-functionalized as the matrix to immobilize the primary antibodies (Ab(1)). The unique 3D flower-like nanostructure of ZnO provided a higher surface area for the capture of proteins. 3D AuPd NFs were employed as the label to immobilize the secondary antibodies (Ab(2)). The unique 3D flower-like nanostructure of AuPd produced a better electrocatalytic performance towards the reduction of hydrogen peroxide (H2O2). Due to the special electrochemical performance of 3D flower-like nanomaterials, the facile and sensitive fabrication of the designed immunosensor was achieved. Under optimal conditions, the designed immunosensor exhibited a wide linear range from 10(-5) ng mL(-1) to 10(2) ng mL(-1) with a low detection limit of 3.2 fg mL(-1) for CEA. It also displayed an electrochemical performance with good reproducibility, selectivity and stability, which would provide potential applications in the clinical diagnosis of other tumor markers.