A Signal-Enhanced Regenerative Electrochemical Aptasensor for Amyloid-β Oligomers Based on Triple-Helix Aptamer Probe

Abstract

Amyloid-β oligomers (AβOs) play an important role in Alzheimer’s disease (AD), and have attracted wide attention as a significant and promising biomarker. Currently, triple-helix aptamer probe (TAP) has yet to fully capture people’s eyes. The previous studies in our group have proved that TAP is an effective alternative to traditional sandwiches or direct detection strategies. Nevertheless, these developed “signal off” sensors suffered from complex nanomaterial preparation procedures and possibility of false positives. Herein, we successfully constructed a signal-enhanced regenerative electrochemical aptasensor (EA) based on TAP strategy to realize reliable assay for AβOs, subtly keeping off false positive responses. In this work, ferrocene (Fc)-labeled complementary strand (CS) (Fc-CS) acted as a signal label, avoiding the need for complex nanomaterials. Fc-CS hybridized with label-free aptamer (Apt) to form TAP on Au electrode (AE). The formation and destruction of TAP structure could adjust the weak and strong DPV signal. Thus, sensitive electrochemical detection for AβOs was achieved with and a low detection limit of 0.47 fM. Moreover, the EA could exhibit outstanding selectivity, specificity, stability, reproducibility and regenerability. Meanwhile, it can be applied to the determination of artificial cerebrospinal fluid (A-CSF) samples, providing a convenient and low consumption platform for practical applications.