Metal-Free Perylene-Based Polyimide Frameworks for Oxygen Reduction-Enhanced Electrochemiluminescence Biosensing

We report a metal-free perylene-based polyimide framework (PDI-PB) as an efficient electrocatalyst for oxygen reduction reaction (ORR)-enhanced cathodic electrochemiluminescence (ECL). PDI-PB enhances reactive oxygen species (ROS) generation via oxygen reduction that significantly amplify the luminol–dissolved oxygen ECL signal. The resulting biosensor enables ultrasensitive detection of dopamine (DA) over a wide linear range (5 × 10 -5 to 100 μM) with a record-low detection limit of 9.76 pM (S/N = 3). The sensor exhibits excellent selectivity, stability, and reproducibility, and was successfully applied to detect DA in human sweat, serum, and urine, yielding recoveries of 97.0–101.1%. Density functional theory (DFT) calculations reveal that PDI-PB’s superior electronic structure facilitates efficient charge transfer and oxygen activation. This work presents a new strategy for metal-free organic electrocatalyst design, combining mechanistic insight with high-performance ECL biosensing for non-invasive health monitoring and clinical diagnostics.