Alzheimer’s disease (AD) is a progressive neurodegenerative disorder affecting millions worldwide,
with cases expected to rise sharply due to aging populations. Early diagnosis is essential
for improving patient outcomes, yet conventional diagnostic methods, such as neuroimaging and
cognitive assessments, often fail to detect AD until significant neuronal damage has occurred.
Biosensors offer a promising alternative by enabling real-time, non-invasive detection of disease
biomarkers. Recent advancements in two-dimensional monolayer materials have enhanced biosensor
sensitivity and specificity, making them viable candidates for AD diagnostics. In this study,
we investigate the adsorption behavior of three novel AD biomarkers—Glycine, L-Diphenylalanine
(FF), and D-Serine—on pristine, B-, Ti-, and Ca-doped graphene using density functional theory
(DFT) calculations. Our findings indicate that Glycine, FF, and D-Serine are weakly adsorbed
on pristine graphene with adsorption energies of -0.197, -0,075, and -0.219 eV while they were
strongly adsorbed onto B-, Ti-, and Ca- doped graphene with the highest adsorption energies
of each molecule being -0.293, -6.16, and -1.63 eV respectively. The electronic properties of B-,
Ti-, and Ca- doped graphene also changed significantly compared to pristine graphene following
biomarker adsorption. For example, the calculated recovery times of FF on B-, Ti-, and Ca-doped
graphene were 3.21 × 10⁻¹⁰, 2.32 × 10⁸⁹, and 0.17 seconds, respectively, suggesting that Ca-doped
graphene is the most suitable of the three candidates for biosensing applications. Further exploration
of the charge transfer between the biomarkers and doped graphene confirms the potential
of Ca-doped graphene over the others. Overall, our findings suggest that Ca-doped graphene is
a better candidate for Glycine, FF, and D-Serine detection compared to B-doped and Ti-doped
graphene.

Xuan Luo

Appearances