Characterization and evaluation of the ability of graphene quantum dots to affect α-synuclein aggregation in...

Synucleinopathies, including Parkinson's disease and multiple system atrophy (MSA), are neurodegenerative disorders characterized by aggregation of α-synuclein (ASN). Nanomaterials capable of modulating protein misfolding represent a potential intervention strategy. Here, we synthesized graphene quantum dots (GQDs) and systematically evaluated their physicochemical properties and biological activity against ASN aggregation. The GQDs were characterized using spectroscopic, electron microscopy, and colloidal techniques to determine surface chemistry, charge, optical properties, and crystalline structure. Biological evaluation demonstrated cytocompatibility in human dermal fibroblasts (IC_{5 0} = 90 µg mL^-1 at 24 h) with assessments of DNA damage and inflammatory responses. Functionally, GQDs destabilized preformed ASN fibrils in a cell-free assay, as evidenced by reduced Thioflavin-T fluorescence. In primary murine dopaminergic neurons, GQDs decrease pS129-ASN inclusion formation without compromising neuronal viability. Most importantly, intranasal administration of GQDs in an MSA mouse model reduced ASN immunoreactivity in the brain. Collectively, our data indicate that the synthetized GQDs are bioactive and can modulate ASN aggregation across cell-free, neuronal, and in vivo models. Importantly, physicochemical properties govern nano - bio interactions, providing a rationale for further refinement of GQDs as a biomaterial platform for synucleinopathy-related applications.