Nanoelectrical characterization of individual exosomes secreted by Aβ₄₂-ingested cells using electrostatic force microscopy

Quantifying the physical properties of individual exosomes containing amyloid-β₄₂ (Aβ₄₂) is crucial for a better understanding of an underpinning mechanism of Alzheimer’s disease expression which is associated with the Aβ₄₂ transfer. Because of the lack of proper tools, however, there have been very few studies on how the amount of Aβ₄₂ affects the physical properties of exosomes. To answer the question, we investigated the physical properties of exosomes secreted by neuroblastoma by probing individual exosomes using electrostatic force microscopy. Interestingly, we observed that when the higher concentration of Aβ₄₂ oligomers was fed to cells, the higher surface charge of the exosomes appeared. This result indicates that the exosomes contain more Aβ₄₂ with the increase in Aβ₄₂ concentration in cell media, implying that they serve as transport vesicles for Aβ₄₂. Our approach could help to better understand how the neuronal exosomes are related to the propagation of neurodegenerative diseases and to seek how to make an early diagnosis of those diseases.