Comparative anti-amyloidogenic potential of pristine and nitrogen doped graphene quantum dots against amyloid beta...

This study investigates the effect of nitrogen doping of graphene quantum dots (GQDs) upon their ability to inhibit the fibrillation of amyloid beta fragments containing 1-42 amino acids (Aβ). Misfolded aggregates of Aβ have been implicated in the pathogenesis of Alzheimer's disease, the most prevalent form of dementia. We employed spectroscopic and microscopic techniques to characterize both quantum dots. Anti-amyloidogenic potential was assessed using circular dichroism spectroscopy and the thioflavin T binding. Atomic force microscopy was utilized to characterize the morphological and nanomechanical properties of Aβ fibrils following treatment with the quantum dots. We observed that nitrogen doping significantly alters the absorbance and fluorescence emission profiles, likely due to an increased surface charge density induced by the incorporation of nitrogen atoms. N-GQDs exhibited superior anti-amyloidogenic activity in comparison to pristine quantum dots. This effect varied in accordance to the dose. Using the data of MTT, trypan blue exclusion, differential staining and apoptosis assays on SH-SY5Y neuroblastoma cells, we infer that adsorption of Aβ on doped quantum dots was accompanied with reduction in the stiffness of fibrils and their toxicity to the cells.