Sandwich-type electrochemical immunosensor for ultrasensitive detection of prostate-specific antigen using palladium-doped cuprous oxide nanoparticles

Abstract

A new and facile sandwich-type electrochemical immunosensor is proposed for the ultrasensitive detection of prostate-specific antigen (PSA) based on Au nanoparticles (Au NPs) and palladium-doped cuprous oxide nanoparticles (Pd@Cu₂O NPs). In this study, Au NPs were used as a substrate material to immobilize primary antibodies (Ab₁) and to accelerate electron transfer. The Pd@Cu₂O NPs were obtained through the prepared cuprous oxide nanoparticles (Cu₂O NPs) by the in situ reduction of palladium chloride (PdCl₂). The immunosensor was employed as a label for secondary antibodies (Ab₂), presenting efficient electrocatalytic activity toward the reduction of hydrogen peroxide (H₂O₂). Under optimal conditions, the proposed immunosensor exhibited a wide linear response range from 10⁻⁵ to 100 ng mL⁻¹ with a low detection limit of 2 fg mL⁻¹. We thus established and demonstrated a simple, fast, and sensitive strategy for the ultrasensitive detection of PSA, which could find promising application in clinical diagnoses and other fields.