Terahertz metal-graphene hybrid metamaterial for monitoring aggregation of Aβ_16–22 peptides

The aggregation of amyloid-beta (Aβ) protein into amyloid fibrils represents a major hallmark of Alzheimer's disease. Detection of Aβ aggregation has great significance for early diagnosis of the disease. Here, we propose one novel Terahertz metal-graphene hybrid metamaterial to monitor the fibrillization of Aβ_16–22 peptides. We demonstrate the formation of Rabi splitting modes with two distinctive spectral transmission peaks on the hybrid metamaterial sensor. Graphene electron doping and Fermi energy level vary in different phases of Aβ_16–22 peptides aggregation formation. As change on graphene Fermi level leads to the shifting of the Rabi splitting peaks, by monitoring the position of Rabi splitting peaks, we can very sensitively monitor the Aβ_16–22 peptides aggregation process. Moreover, our molecular dynamics simulations at the atomic level reveal that the variation of graphene electron doping is caused by the reduction of π-π stacking between graphene and Aβ_16–22 peptides in aggregation process. By successfully linking the Fermi level shift to the shifting Rabi splitting peaks, the demonstrated novel sensor paves the way for a new type of simple, label-free, and highly sensitive hybrid graphene metamaterial sensing scheme for Alzheimer's detection and broader applications.