DNAzyme-driven tripedal DNA walker mediated signal-on and label-free for electrochemical detection of α-synuclein oligomers

In the case of Parkinson's disease (PD), the soluble alpha-synuclein (alpha-syn) oligomer is considered to be a reliable molecular biomarker. Developing easy-to-prepare, cheap, sensitive, and reliable techniques for the detection of alpha-synuclein oligomers is therefore a vital task. In this work, based on Mg2+-dependent DNAzyme (MNAzyme)-driven tripedal DNA walker tactics, we designed an innovative label-free and signal-on electrochemical apta-sensor for alpha-syn oligomer quantification. alpha-syn oligomer-triggered tripedal DNA walkers outperformed common DNA walkers with the larger area of walking and accelerated walking kinetics, and facilitated greater amplifi-cation efficiency. With the assistance of MNAzyme, free-running tripedal DNA walkers could rapidly and continually scissor DNA hairpins (HPs), thereby unlocking numerous active G-quadruplex-forming sequences. Afterwards, G-quadruplex/hemin complexes could be formed by hemin further recognizing these G-quadruplexes and generated an enhanced current signal. Benefiting from tripedal DNA walker and MNAzyme dual signal amplification, we achieved a superior detection limit of 0.46 fM as well as a broad linear range of 1 fM to 10 pM. After being applied to alpha-syn oligomer detection in human serum samples, this novel electrochemical aptasensor demonstrated a high degree of sensitivity, anti-interference, and reproducibility, indicating its great potential for bioanalysis in complex biological environments.

Automated summary

In Parkinson's disease, the soluble alpha-synuclein oligomer is a reliable molecular biomarker. This study presents an innovative label-free and signal-on electrochemical apta-sensor for the quantification of alpha-syn oligomers. The tripedal DNA walkers triggered by alpha-syn oligomers outperformed common DNA walkers, leading to greater amplification efficiency. With the assistance of Mg2+-dependent DNAzyme, the tripedal DNA walkers could scissor DNA hairpins, generating enhanced current signals. The developed aptasensor demonstrated high sensitivity, anti-interference, and reproducibility, making it a promising tool for bioanalysis in complex biological environments.