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

Amyloid-beta oligomers (A beta O) 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 A beta O 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 A beta O. 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 A beta species, this label-free sensor was used to monitor the process of A beta protein aggregation, which was validated by atomic force microscope analysis. In addition, the aptasensor can be used to detect A beta O in artificial CSF with satisfying accuracy. To our knowledge, it is first label-free aptasensor for an A beta O assay based on EIS that works in artificial CSF and can be used for monitoring A beta 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 A beta plaques degradation.