A novel electrochemical biosensor with molecularly imprinted polymers and aptamer-based sandwich assay for determining amyloid-β oligomer

Amyloid-beta oligomers (A beta Os) are highly toxic species involved in Alzheimer's disease (AD). Hence, a reliable detection method for A beta Os, which are promising potential therapeutic targets and biomarkers for AD, is of great significance for improving the diagnosis of AD. Herein, a novel sandwich assay electrochemical biosensor was developed for highly sensitive and selective detection of A beta O, usingmolecularly imprinted polymers (MIPs) and aptamer as the recognition element. Instead of using an antibody to recognize the A beta O target molecules, the A beta O in the samples were captured by the film of MIPs and the A beta O-specific aptamer, forming a MIPs/target/aptamer sandwich assay for the highly selective detection of A beta O. The A beta O-specific aptamer was immobilized on the surface of core-shell nanoparticles that combined silver nanoparticles with silica nanoparticles (SiO2@Ag NPs). The highly sensitive electrochemical signal from the sandwich assay was generated by using a small amount of A beta O to trigger a large number of electrochemically active Ag NPs. Under the optimized conditions, the developed biosensor showed good linearity in the concentration range of 5 pg mL(-1) to 10 ng mL(-1) with a limit of detection of 1.22 pg mL(-1). The biosensor also showed excellent specificity, reproducibility and stability. In addition, the feasibility of detecting A beta O in human serum was successfully verified, demonstrating the promising potential of this approach for clinical research and the early diagnosis of AD. (c) 2020 Elsevier B.V. All rights reserved.