A sandwich-type electrochemical immunosensor prepared with graphyne-Au triangular nanoprisms and MoS2-AuPtCu hexagonal nanoframes for the detection of human growth/differentiation factor 15

Growth differentiation factor 15 (GDF-15) is an important biomarker for the early diagnosis and prognostic evaluation of cardiovascular disease (CVD). Monitoring the expression level of GDF-15 in serum can enable early diagnosis evaluation of CVDs. Therefore, the realization of high-sensitivity GDF-15 detection platforms is clinically significant. To detect GDF-15, we developed a sandwich-type electrochemical immunosensor based on hydrogen peroxide (H 2 O 2 ) as a signal source. AuPtCu hexagonal metal nanoframes (AuPtCu HNFs) loaded onto molybdenum disulfide (MoS 2 ) nanosheets (MoS 2 -AuPtCu HNF) as secondary antibody labels provided signal amplification. The hollow three-dimensional hexagonal-shaped structure of the AuPtCu nanoframe exposed abundant active sites and exhibited excellent catalytic properties. MoS 2 nanosheets with flower-like structures and large specific surface areas can effectively load AuPtCu HNFs. The combination of AuPtCu HNFs and MoS 2 nanosheets enhanced the catalytic activity toward H 2 O 2 reduction and realized signal amplification. For the substrate material, two-dimensional Au triangular nanoprisms (Au TNPs) with two large surface planes were hybridized with graphyne (GDY) nanosheets. The obtained GDY-Au TNPs exhibited low catalytic activity and excellent electrical conductivity; therefore, they were used to load primary antibodies to effectively enhance the sensitivity. Under optimal conditions, the constructed immunosensor exhibited a wide detection range of 500 fg/mL to 50 ng/mL and low detection limit of 0.212 pg/mL. Moreover, the GDF-15 content in human serum was tested with satisfactory results. Therefore, the constructed immunosensor can sensitively and accurately detect GDF-15 for the early diagnosis of CVD.