Nanomaterial Enhances the Performance of Amyloid-beta Biosensing for Alzheimer's Disease Diagnosis

Background Highly sensitive, accurate, and low-cost detection systems are gaining interest for early intervention in the progression of Alzheimer's disease (AD). Amyloid-beta (A beta), a peptide highly involved in the progression of AD, is found in abundance in patients with severe AD.Objective This research focused on developing an A beta oligomer (A beta O) biosensor using a single-walled carbon nanotube-modified (SWCN) interdigitated electrode (IDE) sensor.Methods The SWCN was functionalized onto the sensor surface through an amine linker, followed by the attachment of an aptamer-gold nanoparticle (GNP) complex, which was used to capture the A beta O.Results The GNP-aptamer was saturated at 500 nM on the SWCN surface, and A beta O was detected using a sandwich consisting of aptamer-A beta O-antibody. The SWCN modification increased the number of aptamer attachment sites on the IDE, while the aptamer and antibody conjugation with GNP enhanced A beta O interaction. This sandwich assay detected A beta O at concentrations as low as 10 fM, with a linear regression coefficient (y = 2.9189x - 2.076; R2 = 0.9544). Furthermore, A beta O-spiked artificial CSF was detected without interference, as confirmed by the increased current responses. No significant changes were recorded with control proteins, including alpha-synuclein, IgG antibody, and a complementary aptamer, indicating specific A beta O detection.Conclusion This SWCN modified IDE-based sandwich detects A beta O at its lower level and contributes to the early diagnosis of AD.