Highly sensitive detection of thyroglobulin based on sandwich-type electrochemical immunoassay

As a dimeric protein, thyroglobulin (Tg) is an important biomarker for different thyroid cancer (DTC), so designing effective method to detect Tg is of great significance. In this work, by preparing β-cyclodextrin (CD) functionalized carbon nanotubes (CNTs) nanohybrid (CD-CNTs) as carrier to immobilize primary antibody (Ab₁) of Tg, assembling sulfydryl ferrocene (Fc) and secondary antibody (Ab₂) on the surface of nanogold (Au) as signaling amplifier (Ab₂-Au-Fc), a simple and sensitive sandwich-type electrochemical immunoassay (STEM) of Tg was designed herein for the first time. In brief, CNTs show large surface area and conductivity, while CD offers superior host-guest recognition capability that can bound with Ab₁; meanwhile, Fc probe can offer stable electrochemical signal that is proportionable to the concentration of Tg. Under the optimum conditions, the proposed STEM platform shows excellent sensing results for Tg detection: a considerable low analytical detection (0.5 ng mL^-1) and wide linearity (2 to 200 ng mL^-1), suggesting the designed STEM platform offers potential real applications for detect Tg.