Let it glow - Fluorescent sensing of PFOS in water using Spirulina-based phycocyanin-carbon quantum dots:...

Per- and polyfluoroalkyl substances (PFAS), commonly known as "forever chemicals" due to their exceptional environmental persistence, are an emerging class of contaminants that pose significant risks to water quality and human health. In this study, we developed a direct luminescence-based sensing approach for the detection of perfluorooctane sulfonate (PFOS) in water using commercial phycocyanin (CCPC), extracted C-phycocyanin (ECPC), and carbon quantum dots (CQDs) synthesized from ECPC. All three sensor materials exhibited strong luminescent profiles, which were efficiently quenched through an aggregation-induced quenching mechanism upon exposure to PFOS. Quenching efficiencies of 82.61, 82.49, and 65.59% were obtained for CCPC, ECPC, and CQDs, respectively. Correspondingly, ECPC and CQDs demonstrated high sensitivity toward PFOS, achieving limits of detection of 1.48 nM and 1.73 nM, respectively. The method's accuracy and precision were validated through spiked tap water and bottled drinking water samples, yielding recovery values of 102.63% for ECPC and 106.03% for CQDs. Additionally, theoretical calculations were conducted to elucidate the composition, binding interactions, and complex formation between the prepared sensors and PFOS, supporting the experimental observations. Overall, this study presents a rapid, sensitive, cost-effective, and environmentally friendly sensing platform with strong potential for real-time, on-site monitoring of PFOS in aquatic environments.