Reusable photo-crosslinked acrylate networks incorporating coumarin and S-CQDs for trace-level picric acid detection

Translating liquid-based luminescent nanomaterials into functional solid-state systems remains a major hurdle in environmental analysis. To address this limitation, this work presents the development of a structurally durable, multi-component polymeric sensor specifically engineered for the trace-level recognition of picric acid (PA). The sensing platform was formulated by embedding heteroatom-modified carbon nanodots (S-CQDs) alongside a custom-synthesized acrylated coumarin precursor within a tightly cross-linked UV-cured acrylate matrix. By confining the active phase within this polymeric architecture, the water-dispersible quantum dots are retained within a solid support while preserving their luminescent behavior. Upon exposure to PA, the formulated composite film (F2) exhibits pronounced fluorescence attenuation. The observed quenching is interpreted as an association-assisted process with possible contributions from photoinduced electron transfer (PET) and spectral-overlap-related effects. Under the optimized conditions, the sensor exhibited a linear response over 9.70 × 10 −8 –4.05 × 10 −6 mol L −1 (R 2 = 0.9924), with a limit of detection of 2.25 × 10 −8 mol L −1 , a limit of quantification of 7.50 × 10 −8 mol L −1 , and a response time of approximately 20 s. The F2 film showed preferential fluorescence quenching toward PA compared with the investigated metal ions, aromatic species, and nitroaromatic compounds. The film retained approximately 95% of its baseline emission after 150 sensing/regeneration cycles and after two months of ambient storage. Practical applicability was demonstrated using real soil samples spiked with PA prior to extraction, yielding recoveries of 98.5–102.4% with RSD values of 1.4–2.1%. These results support the use of the S-CQD/acrylated-dicoumarin acrylate film as a reusable solid-state fluorescence platform for PA determination.