Ultrasensitive sandwich-type prostate specific antigen immunosensor based on Ag overgrowth in Pd nano-octahedrons heterodimers decorated on amino functionalized multiwalled carbon nanotubes

Abstract

A novel and ultrasensitive sandwich-type electrochemical immunosensor was designed for quantitative detection of prostate specific antigen (PSA). The Ag overgrowth in Pd nano-octahedrons, developed Pd-Ag heterodimers (Pd-Ag HDs), loaded on amino functionalized multiwalled carbon nanotubes (MWCNTs-NH2) were employed as labels of secondary antibodies (Ab2). The synergistic effect of Pd-Ag HDs exhibited high electrocatalytic activity towards the reduction of H2O2. MWCNTs-NH2 with good dispersion, plentiful amino groups and large specific surface area, could load a large number of Pd-Ag HDs to enhance the sensitivity and amplify the signal of the immunosensor. Moreover, the electroplated gold nanoparticles (Au NPs) were employed for the immobilization of primary antibodies (Ab1). Au NPs with excellent conductivity could enhance the electron transport between substrate material and electrode surface, and improve the sensitivity of immunosensor. Under optimal conditions, the electrochemical immunosensor exhibited a wide linear range of 0.1pg/mL–30ng/mL towards PSA, and a low detection limit of 0.03pg/mL (S/N=3). The proposed immunosensor exhibited good sensitivity, reproducibility and stability for the quantitative detection of PSA, which hold a great potential in clinical and diagnostic applications.