Electrodeposition of gold–platinum alloy nanoparticles on carbon nanotubes as electrochemical sensing interface for sensitive detection of tumor marker

Electrodeposition of gold–platinum alloy (Au–PtNPs) on carbon nanotubes as electrochemical sensing interface and HRP as blocking agent for the fabrication of high sensitive immunosensor. [Display omitted] ► In this work, we proposed a novel electrochemical sensing surface. ► The sensing surface possessed larger electro-active areas and higher conductivity due to the introduction of MWCNTs. ► The signal could be amplified effectively by synergetic catalysis effect of Au–PtNPs and HRP towards the reduction of H 2O 2. ► Biomolecules could be immobilized on the surface of Au–PtNPs tightly with the bioactivity kept well. ► The simple fabrication method provided a new potential for the future development of practical devices for clinical diagnosis application. A novel electrochemical sensing interface, electrodeposition of gold–platinum alloy nanoparticles (Au–PtNPs) on carbon nanotubes, was proposed and used to fabricate a label-free amperometric immunosensor. On the one hand, the multiwalled carbon nanotubes (MWCNTs) could increase active area of the electrode and enhance the electron transfer ability between the electrode and redox probe; on the other hand, the Au–PtNPs not only could be used to assemble biomolecules with bioactivity kept well, but also could further facilitate the shuttle of electrons. In the meanwhile, horseradish peroxidase (HRP) instead of bovine serum albumin (BSA) was employed to block the possible remaining active sites and avoid the nonspecific adsorption. With the synergetic catalysis effect of Au–PtNPs and HRP towards the reduction of hydrogen peroxide (H 2O 2), the signal could be amplified and the sensitivity could be enhanced. Using alpha-fetoprotein (AFP) as model analyte, the fabricated immunosensor exhibited two wide linear ranges in the concentration ranges of 0.5–20 ng mL −1 and 20–200 ng mL −1 with a detection limit of 0.17 ng mL −1 at a signal-to-noise of 3. Moreover, the immunosensor exhibited good selectivity, stability and reproducibility. The developed protocol could be easily extended to other protein detection and provided a promising potential in clinical diagnosis application.