Label-free electrochemical monitoring of oxidative-induced aggregation of cofilin-1.

Oxidation of human cofilin-1 (CFL-1) protein has been linked to dysregulation and may promote aggregation into amyloid-like structures implicated in neurodegenerative disorders. Herein, CFL-1 was intentionally oxidized upon incubation with N-chlorotaurine to monitor aggregation through direct electrochemistry. Solution-phase characterization by size-exclusion chromatography (SEC), dynamic light scattering (DLS), fluorescence, and circular dichroism spectroscopy confirmed successful oxidation and showed dimers to high-molecular-weight aggregates exclusively under oxidizing conditions. The electroactive amino acid employed to assess the oxidative-induced aggregation was tyrosine (Tyr), as identified by the hydrophobicity plot of CFl-1. During the first 5 h, CFL-1 adsorbed onto screen-printed carbon electrodes showed a peak potential shift from 0.78 (native state) to 0.64 V, with a concomitant current increase consistent with hydrophobic exposure and closer Tyr proximity to the electrode surface. Beyond 5 h, the progressive current decrease indicated aggregate formation, likely hiding the Tyr residues and suppressing the electrode reaction. SEC and DLS data corroborated these findings, showing coexistence of monomers, dimers, tetramers, and hexamers, with monomers predominating initially and dimers and hexamers after 5 h. Overall, the proposed label-free electrochemical approach effectively detected early-stage CFL-1 aggregation and may help build cost-effective and user-friendly early detection strategies.