Electroactive Fe₃O₄/α-Fe₂O₃@Au nanocomposites driven label-free electrochemical aptasensor with magnetic...

Alpha-fetoprotein (AFP) is a crucial biomarker for several cancers' diagnosis, especially hepatocellular carcinoma; therefore, early accurate detection of AFP is of vital significance. Herein, a label-free electrochemical aptasensor with magnetic self-assembly of heterogeneous Fe₃O₄/α-Fe₂O₃ nanosheets is presented for rapid and accurate detection of AFP. The sensor was mainly designed by loading Au nanoparticles (AuNPs) on the surface of Fe₃O₄/α-Fe₂O₃ nanosheets and further binding with aptamer probes through Au-S bonds, and the target could be captured by the high affinity and specificity with the aptamer. Furthermore, owing to the excellent superparamagnetization of Fe₃O₄/α-Fe₂O₃@Au nanocomposites, rapid magnetic separation and magnetic self-assembly could be realized, actualizing quantitative determination of AFP through current changes. Under optimal conditions, the aptasensor exhibited excellent quantitative determination performance in the 10 pg/mL to 1 μg/mL range, and the detection limit was 1.31 pg/mL. In addition, the aptasensor demonstrated favorable reproducibility, stability, selectivity, and achieved satisfactory recovery (97.34-104.60%) in human serum samples, providing a practical strategy for clinical detection of AFP.