Gold nanoparticles assisted sensitivity improvement of interdigitated microelectrodes biosensor for amyloid-β detection in plasma sample

Amyloid-β (Aβ) is a peptide that is produced in the brain and carried across the blood brain barrier to the blood. It is an important biomarker for the blood-based diagnosis of early stage Alzheimer's disease (AD). However, the challenges of using blood Aβ are that there are several isoforms of the peptide and that the difference in concentration of the peptide in the blood between AD patient and normal individual is extremely low. Here, we developed interdigitated microelectrodes (IMEs) as an impedance biosensor for the blood-based Aβ detection using gold nanoparticles (AuNPs) sandwich assay. It provided logarithmically linear sensitivity and enhancements in the detection limits of approximately 2.87-fold and 74.84 %, respectively. We prepared mouse plasma sample from the blood of double-mutated APP/PS1 transgenic (TG) and wild-type (WT) mouse group, and AD diagnostic ability was tested by Aβ detection in the plasma samples. Our results showed that AuNPs sandwich assay assisted Aβ detection successfully discriminated TG and WT mouse groups. Thus, with this sensing system, we detected Aβ with high sensitivity and selectivity. This Aβ sensing system with AuNPs sandwich assay could lead to a significant advance in human blood sample based clinical diagnosis.