A sandwich-type electrochemical immunosensor using rGO-TEPA-Thi-Au as sensitive platform and CMK-3@AuPtNPs as signal probe for AFP detection

Alpha-fetoprotein (AFP) plays an important role as a marker in the clinical diagnosis of cancer. However, the sensitive detection of AFP in clinical samples is still challenging. Therefore, we developed a highly sensitive electrochemical immunosensor for the effective detection of AFP. In this study, thionine (Thi) and gold nanoparticles (AuNPs) co-modified reduced graphene oxide-tetraethylene pentamine (rGO-TEPA-Thi-Au), which was used as the immunosensor platform to fix the primary antibody (Ab 1 ), leading to a large improvement in the sensitivity of the immunosensor. Furthermore, ordered mesoporous carbon (CMK-3) modified with AuPt binary nanoparticles ( [email protected] ) was used as the signal probe for further signal amplification because CMK-3 can provide a large specific surface area for in-situ reduction of AuPtNPs with good conductivity. Therefore, a dual signal amplification was observed in the amperometric i-t curve, and the detection limit of the proposed immunosensor was effectively enhanced. The constructed immunosensor showed a wide linear range of 0.005 to 100 ng mL −1 and a low detection limit of 0.0022 ng mL −1 at S/N = 3. Furthermore, the proposed immunosensor exhibited excellent stability and recovery, demonstrating its potential for clinical applications.