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 (H2O2) as a signal source. AuPtCu hexagonal metal nanoframes (AuPtCu HNFs) loaded onto molybdenum disulfide (MoS2) nanosheets (MoS2-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. MoS2 nanosheets with flower-like structures and large specific surface areas can effectively load AuPtCu HNFs. The combination of AuPtCu HNFs and MoS2 nanosheets enhanced the catalytic activity toward H2O2 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.