Blue Fluorescent Carbon Dots Synthesized From PBAT and PET Waste Plastics and Their Detection of Gefitinib

Blue fluorescent carbon dots (CDs) were synthesized in this study from poly (butylene adipate co ‐terephthalate) (PBAT) and poly (ethylene terephthalate) (PET) waste through a sequential carbonization and hydrothermal treatment. The nanoparticles exhibited a spherical morphology with a narrow size distribution of 1.3–2.5 nm, abundant hydrophilic surface groups, and excellent dispersibility in aqueous solution. The CDs exhibited strong blue fluorescence with a quantum yield (QY) of 7.4% and remarkable stability. The fluorescence was selectively quenched by gefitinib primarily via a Förster resonance energy transfer (FRET) mechanism. The developed sensor showed a linear detection range of 0–30 μM, a low detection limit of 0.8433 μM, and outstanding anti‐interference capability against common biomolecules and structurally similar drugs. The spiked recovery rates in real samples ranged from 96.7% to 103.0%, with the relative standard deviations (RSDs) less than 3.0%, demonstrating the probe's capability for detecting gefitinib in complex practical matrices. The proposed sensor shows great potential for applications in therapeutic drug monitoring and clinical diagnostics, offering a promising solution for both environmental sustainability and analytical science.