Carbon Nanodot-Sensitized Modulation of Alzheimer's β-Amyloid Self-Assembly, Disassembly, and Toxicity.

The self-assembly of amyloidogenic peptides into β-sheet-rich aggregates is a general feature of many neurodegenerative diseases, including Alzheimer's disease, which signifies the need for the effective attenuation of amyloid aggregation toward alleviating amyloid-associated neurotoxicity. This study reports that photoluminescent carbon nanodots (CDs) can effectively suppress Alzheimer's β-amyloid (Aβ) self-assembly and function as a β-sheet breaker disintegrating preformed Aβ aggregates. This study synthesizes CDs using ammonium citrate through one-pot hydrothermal treatment and passivates their surface with branched polyethylenimine (bPEI). The bPEI-coated CDs (bPEI@CDs) exhibit hydrophilic and cationic surface characteristics, which interact with the negatively charged residues of Aβ peptides, suppressing the aggregation of Aβ peptides. Under light illumination, bPEI@CDs display a more pronounced effect on Aβ aggregation and on the dissociation of β-sheet-rich assemblies through the generation of reactive oxygen species from photoactivated bPEI@CDs. The light-triggered attenuation effect of Aβ aggregation using a series of experiments, including photochemical and microscopic analysis, is verified. Furthermore, the cell viability test confirms the ability of photoactivated bPEI@CDs for the suppression of Aβ-mediated cytotoxicity, indicating bPEI@CDs' potency as an effective anti-Aβ neurotoxin agent.