Fluorescence Resonance Energy Transfer (FRET)-based ThT free sensing of beta-amyloid fibrillation by carbon dot-Ag composites

Abstract

Amyloid-beta proteins that form cytotoxic aggregates called amyloid-β derived diffusible ligands are responsible for various neurodegenerative diseases like Alzheimer’s and Parkinson’s disease. Novel methods for the early detection of such aggregates and inhibition of further fibrillation are highly important and need in the current situation. In this paper, we present a novel method based on fluorescence resonance energy transfer (FRET) between carbon dots and Ag nanoparticle for sensing various fibrillation stages of beta-amyloid proteins. The addition of Ag nanoparticles to carbon dot colloid is found to significantly enhance the inhibition of beta-amyloid fibrillation due to the modified hydrophobic and electrostatic interactions introduced by Ag nanoparticles and is monitored using thioflavin T (ThT) assay. Further, fluorescence quenching of carbon dots in the presence of Ag particles is found to get reduced with the increase in the incubation time of beta-amyloid fibrils. We could observe a linear trend in the variation of Stern–Volmer constants calculated based on FRET between carbon dots and Ag nanoparticles with the incubation time of beta-amyloid, indicating the potential of using the proposed FRET-based method for sensing beta-amyloid fibrillation.