Wangngae S.Thisan S.Kumphune S.Vettavong T.Thepmongkorn W.Chaiwat W.Sutthasupa S.Mahidol University2025-11-222025-11-222025-11-14ACS Applied Polymer Materials Vol.7 No.21 (2025) , 14711-14729https://repository.li.mahidol.ac.th/handle/123456789/113169We report fluorescent, amino acid–based polymeric chemosensors, Poly-Cou-Cys, which were synthesized via ROMP using coumarin (Cou)-cysteine (Cys)-functionalized norbornene monomers. The resulting materials exhibit a selective Cd²⁺turn-off-turn-on response and subsequent anion recognition. Spectroscopic measurements were performed in DMSO solution (excitation = 350 nm, emission = 411 nm). The Cd²⁺turn-off mechanism relies on the Cd²⁺ion preferentially coordinating with the polymer’s soft sulfur donor atoms, along with other heteroatoms of coumarin and cysteine, leading to structural rigidification and fluorescence quenching. This mechanism was supported by¹H NMR and ultraviolet–visible (UV–vis) spectroscopy. The limit of detection (LOD) for Cd²⁺was 55.10 nM (Polymer) and 41.94 nM (MWCNTs composite). The signal was restored (turn-on response) by biologically relevant anions: ATP, HS^–, and H<inf>2</inf>PO<inf>4</inf>^–. This anion recognition mechanism operates by displacing the bound Cd²⁺ion. The most effective anions showed LOD values of 12.26 nM for ATP, 18.16 nM for HS^–, and 13.41 nM for H<inf>2</inf>PO<inf>4</inf>^–. The probes demonstrated clear on–off-on fluorescence cycles in solution and on test strips. The systems also enabled Cd²⁺detection in artificial saliva. These results highlight the potential of this sensor for environmental Cd²⁺monitoring and for detecting clinically relevant anion biomarkers.Materials ScienceChemical EngineeringChemical EngineeringChemistryArticleSCOPUS10.1021/acsapm.5c030372-s2.0-10502188116326376105