An ultrasensitive aptasensor for the analysis of Aβ oligomers in serum

It is one of the great challenges to improve the sensitivity for early detection of biomarker in Alzheimer's disease (AD). In this work, an electrochemical aptasensor was prepared based on thionine (Th) - functionalized three - dimensional carbon nanomaterials (reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNTs) immobilized aptamer for the analysis of Aβ oligomers (AβO), one of the AD biomarkers. Th, the positively charged planar aromatic molecule, could form a large number of π - conjugated structures with rGO and MWCNTs, thereby bringing extra stability to the conjugated macromolecules and improve the structural stability and capacitive properties of Th-rGO-MWCNTs nanocomposites. Under the optimal conditions, DPV response decreased with the increase of AβO concentration. The aptasensor has a good linear range of 0.0443 pM to 443.00 pM with a LOD of 0.01 pM. It also has excellent stability and selectivity for AβO detection. This aptasensor thus has a great potential for early diagnosis of AD.