A Rapid, Sensitive, and Specific Detection of Aggregated α-Synuclein by a Liposome-Immobilized Cantilever Sensor

Parkinson’s disease (PD) is characterized by dopaminergic cell loss and the formation of Lewy bodies, of which the main component is aggregated and fibrillized$\alpha $-synuclein (aSyn). Recent studies suggested that ultratrace amounts of aSyn aggregates are also present in biofluid specimens, and they can serve as a biomarker for PD. Because aSyn has been shown to possess a prion-like property, we attempted to enhance the sensitivity and specificity of a cantilever microsensor to detect aSyn aggregates by exploiting the properties of self-templating assembly and lipid interaction on the surface of liposome-immobilized cantilever sensor. We found that the liposome-immobilized cantilever sensor was able to successfully detect aSyn fibrils at a very low concentration (100 pg/mL), and the addition of aSyn monomers, which were converted into fibrils in the presence of aSyn aggregates and further acted as a template for fibrillization, lowered the detection limit to 10 pg/mL. The sensitivity of this cantilever sensor was comparable to or slightly superior to that of enzyme-linked immunosorbent assay (ELISA). Moreover, the lag time for the detection of aSyn fibrils has been significantly reduced to 100–120 min, compared to the tens of hours needed in conventional ELISA, real-time quaking-induced conversion (RT-QuIC), and protein misfolding cyclic amplification (PMCA) assays. Finally, preliminary measurements of aSyn aggregates showed the possibilities of discriminating serum from PD and non-PD patients. The liposome-immobilized cantilever sensor could serve as a promising tool for the early or preclinical diagnosis of PD.