Electrochemical Biosensing Platform based on Dual Detection of α-Synuclein and Quinolinic Acid as Neurological Diseases Biomarkers: Probe-less Point-of-Care Diagnostics of Early-Stage Parkinson's Disease

Neurological disorders like Parkinson disease (PD) present significant diagnostic challenges due to the lack of cost-effective and reliable biomarkers. This study aimed to develop an advanced electrochemical biosensing platform for detecting PD-associated biomarkers, alpha-synuclein and quinolinic acid, using multi-walled carbon nanotube (MWCNT)-modified screen-printed carbon electrodes (SPCEs). The objective was to create a probe-less, environmentally sustainable electrochemical sensor with high sensitivity and reproducibility for early PD diagnosis. MWCNTs were dispersed in a 1% sodium dodecyl sulfate solution and electrochemically deposited onto SPCEs, with scanning electron microscopy confirming a uniform, mesh-like nanostructure. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were employed for biomarker detection in synthetic human serum. Quinolinic acid displayed a distinct oxidation peak at 0 V (12.54 microA), with DPV showing a linear response across 0.01 mM to 100 mM. Alpha-synuclein detection, enhanced by copper, revealed oxidative peaks at -0.26 V and -0.07 V, and reductive peaks at -0.52 V and -0.32 V, with DPV demonstrating concentration-dependent responses. The developed electrochemical sensors enable rapid, point-of-care (POC) testing for PD, requiring minimal sample volumes and offering portability for use in resource-limited settings. These sensors are crucial for early PD detection, facilitating timely intervention and monitoring disease progression. In conclusion, this probe-less electrochemical platform provides a cost-effective, sustainable tool for PD diagnostics, with significant potential to improve clinical outcomes through accessible and efficient POC applications.