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

• A simple, fast and cheap process for Phosphorylated α-synuclein detection.. • The biosensor is based on a nanostructured laser induced graphene electrode. • Electrochemical properties were amplified by electroplating gold nanoparticles. • AuNPs/LIG immunosensor was verified by measuring blood samples from 8 people. • Feasible and low-cost immunosensor for the diagnosis of Parkinson’s disease. Parkinson’s disease (PD) can be diagnosed by measuring α-synuclein (α-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 α-Syn using electrochemical impedance spectroscopy (EIS), an electrochemical measurement method. Specifically, phosphorylated α-Syn was detected using an antibody that specifically binds to phosphorylated α-Syn. Detection was performed for α-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 (R 2 ) of 0.980. Finally, the fabricated sensor was applied to blood samples from actual patients. The change in charge transfer resistance (R ct ) was measured using EIS in the blood of patients diagnosed with PD and normal controls (NC). the R ct value change was confirmed to be 6.892 % greater in the Parkinson’s disease patient samples. The phosphorylated α-Syn measurement was performed on blood samples from 4 PD patients and 4 NC patients, respectively. As a result, the average R ct change value of EIS in NC was 1.488 %, and the average R ct change value of EIS in PD patients was 8.38 %. It was confirmed that the concentration of phosphorylated α-Syn in the patient’s blood was much higher.