Dendritic Pt@Au nanowires as nanocarriers and signal enhancers for sensitive electrochemical detection of carcinoembryonic antigen

Abstract

Highly sensitive detection of carcinoembryonic antigen (CEA) is very important in clinical diagnosis and treatment assessment of cancers. In this work, we proposed a sensitive and selective electrochemical aptasensor for CEA detection using dendritic Pt@Au nanowires (Pt@AuNWs) as nanocarriers and electrocatalysts. With many advantages such as large specific surface area, good conductivity, excellent electrocatalytic activity and high stability, dendritic Pt@AuNWs were first employed as nanocarriers for immobilizing abundant thiol-terminated CEA aptamer 2 (CEAapt2) and redox-active toluidine blue (Tb), resulting in the formation of AuNWs–CEAapt2–Tb bioconjugate. In the presence of CEA, the proposed bioconjugate was captured onto the electrode surface through “sandwich” tactics. The electrochemical response was then triggered and further enhanced due to the favorable catalysis capacity of dendritic Pt@AuNWs with peroxidase mimic activity for the reduction of H₂O₂ added into the electrolytic cell, from which an improved sensitivity benefited and was successfully achieved. Under the optimal experimental conditions, the proposed aptasensor exhibited a linear response to CEA in the range of 0.001 ng mL⁻¹ to 80 ng mL⁻¹ and the limit of detection (LOD) is 0.31 pg mL⁻¹. Moreover, the aptasensor exhibited good selectivity, stability and reproducibility, which indicated its potential applications in clinical diagnostics.