Electrolyte-Gated Organic Field-Effect Transistor for Monitoring Amyloid Aggregation

Amyloid-β peptide aggregation is a crucial process in neurological disorders such as Alzheimer’s and Parkinson’s diseases. Amyloids tend to assemble first into oligomers and, subsequently, into larger fibrils. The oligomer species are regarded as the primary cause of neurological dysfunction, and hence, they are key biomarkers for diagnosis and therapy. However, this aggregation process is complex to study, typically requiring the use of a combination of techniques and labeling of the biomolecules. Here, we demonstrate that the electrolyte-gated organic field-effect transistor (EGOFET) device is a promising low-cost transducer that can be used to monitor amyloid aggregation using an electrical readout and without the need of labeling. For this purpose, the gold surface of the gate contact was modified with an amyloid-β 1–40 (Aβ1–40) oligomer-specific antibody using cysteine-protein G (cys-PG). The bioengineered Au electrode was implemented as a recognition element to monitor the aggregation kinetics of Aβ1–40, employing two complementary detection measurements: EGOFET and electrochemical impedance spectroscopy (EIS). The maximum amount of oligomer species was detected after 1 h of incubation. Additionally, dynamic light scattering (DLS) data corroborated these results. More broadly, this work shows the potential of EGOFETs as a label-free platform for studying in vitro protein aggregation, which could be appealing in the future for exploring systematically the experimental parameters affecting the aggregation process or for the development of medical treatments that target the reduction of such aggregation.