Polythionine and gold nanostar-based impedimetric aptasensor for label-free detection of α-synuclein oligomers

The neurotoxicity of alpha-synuclein oligomers (alpha-syno) could cause Parkinson's disease (PD) which is an irreversible neurodegenerative disease. In order to diagnose and treat PD patients at an early stage and reduce the damage of sampling to humans, a non-invasive measure is used to analyze ultra-trace levels of alpha-syno. In this work, a new impedimetric aptasensor based polythionine (pTH)/Au nanostars (AuNSs) platform was designed for label-free detection of alpha-syno. The pTH and AuNSs demonstrated excellent electrical conductivity, fast electron transfer capability, and the synergistic amplification effect, which could enhance the sensitivity and improve the limit of detection (LOD). The ssDNA aptamers recognized and bound to alpha-syno via specific bases. Therefore, the ultra-sensitive alpha-syno aptasensor based on pTH and AuNSs presented a LOD of 0.07 aM and a dynamic range from 0.10 aM to 10.00 fM. The aptasensor also displayed good response range, high sensitivity, and low LOD in diluted human plasma samples to provide new methods for early diagnosis of PD.