Chitosan‐enhanced sensitivity of mercaptoundecanoic acid (MUA)‐ capped gold nanorod based localized surface plasmon resonance (LSPR) biosensor for detection of alpha‐synuclein oligomer biomarker in parkinson’s disease.

Alpha‐synuclein oligomers play a crucial role in the early diagnosis of Parkinson's disease (PD). In this study, a mercaptoundecanoic acid (MUA)‐capped gold nanorod (GNR)‐coated and chitosan (CH)‐immobilized fiber optic probe has shown considerable sensitivity of its detection. The proposed U‐shaped fiber optic biosensor based on localized surface plasmon resonance (LSPR) was applied to detect α‐syn oligomer (OA) biomarker. By analyzing OA concentrations, the biosensor achieved a limit of detection of (LOD) 11 pM within the concentration range of 10–100 pM and the sensitivity value was found as 502.69 Δλ/RIU. Upon analysis of the CV% (coefficient of variation) and accuracy/recovery values, it is revealed that the sensor successfully fulfilled the criteria for success, displaying accuracy/recovery values within the range of 80%–120% and CV% values below 20%. This sensor presents significant advantages, including high sensitivity, specificity, and ability to detect very low concentrations of OA. In conclusion, the suggested U‐shaped fiber optic biosensor has the potential to be valuable in the early detection of PD from a clinical perspective. [ABSTRACT FROM AUTHOR]