Monitoring amyloid-β proteins aggregation based on label-free aptasensor

Amyloid-β oligomers (AβO) are important diagnostic markers for Alzheimer's disease (AD) and potential therapeutic targets for treating it. Herein, a simple and label-free electrochemical biosensor is presented for the specific recognition of AβO based on the binding of these biomarkers to ssDNA aptamer receptors. The ssDNA aptamer self-assembles to gold rod electrodes through Au-S interactions and binds specifically to AβO. The novel aptasensor shows a wide linear concentration range from 0.1 to 500 nM with a low detection limit of 0.03 nM as derived from electrochemical impedance spectroscopy invesastigations. Furthermore, owing to the high selectivity among Aβ species, this label-free sensor was used to monitor the process of Aβ protein aggregation, which was validated by atomic force microscope analysis. In addition, the aptasensor can be used to detect AβO in artificial CSF with satisfying accuracy. To our knowledge, it is first label-free aptasensor for an AβO assay based on EIS that works in artificial CSF and can be used for monitoring Aβ protein aggregation. These features, together with its easy fabrication, operation convenience, and effective regeneration, make our new aptasensor a promising tool for the early detection of AD and drug development by monitoring Aβ plaques degradation.