Electrochemical biosensor based on gold nanoparticles/laser induced graphene for diagnosis of Parkinson's disease by detecting phosphorylated α-synuclein in human blood

Parkinson's disease (PD) can be diagnosed by measuring alpha-synuclein (alpha-Syn), a protein expressed in Parkinson's disease patients, through antigen-antibody reaction. In this study, we fabricated a sensor based on laser-induced graphene (LIG) electroplated with gold nanoparticles and detected alpha-Syn using electrochemical impedance spectroscopy (EIS), an electrochemical measurement method. Specifically, phosphorylated alpha-Syn was detected using an antibody that specifically binds to phosphorylated alpha-Syn. Detection was performed for alpha-Syn concentrations ranging from 0.01 to 100 ng/mL. The measurement results indicated a limit of detection of 0.237 pg/mL and a linear correlation coefficient (R2) of 0.980. Finally, the fabricated sensor was applied to blood samples from actual patients. The change in charge transfer resistance (Rct) was measured using EIS in the blood of patients diagnosed with PD and normal controls (NC). the Rctvalue change was confirmed to be 6.892 % greater in the Parkinson's disease patient samples. The phosphorylated alpha-Syn measurement was performed on blood samples from 4 PD patients and 4 NC patients, respectively. As a result, the average Rctchange value of EIS in NC was 1.488 %, and the average Rctchange value of EIS in PD patients was 8.38 %. It was confirmed that the concentration of phosphorylated alpha-Syn in the patient's blood was much higher.