Creatine-based carbon dots with room-temperature phosphorescence employed for the dual-channel detection of warfarin

Herein, a strategy has been proposed to synthesis carbon dots (CDs@creatine) with blue fluorescence and green phosphorescence based on creatine and phosphoric acid. Subsequently, the dual-channel assaying platform was successfully established. To be specific, the fluorescence of CDs@creatine could be effectively quenched by warfarin through inner filter effect and static quenching effect. Meanwhile, the phosphorescence enhancement of CDs@creatine was attributed to intermolecular hydrogen bonds between CDs@creatine and warfarin. Moreover, the proposed strategy through the phosphorescence signal achieved an improved sensitivity than that with the fluorescence for assaying warfarin. • Dual-channel assay of detecting warfarin was successfully established. • Fluorescence quenching and phosphorescence enhancing mechanism was clarified. • Phosphorescence signal showed the higher sensitivity for assaying warfarin. Room-temperature phosphorescence (RTP) materials have harvested enormous attention owing to their advanced optical properties, providing their possibility of the wider applications. Here, we designed a facile strategy to synthesize phosphorus and nitrogen co-doped carbon dots, while creatine provided the carbon and nitrogen source (CDs@creatine). Meanwhile, the as-prepared CDs@creatine exhibited the bright blue fluorescence in aqueous suspension, and showed the green RTP while being fixed on the filter paper. Significantly, the fluorescence of CDs@creatine was quenched by the introduction of warfarin, whereas their RTP was simultaneously enhanced. Specifically, their fluorescence reduction was mainly ascribed to static quenching effect (SQE) and inner filter effect (IFE). In addition, the abundant hydroxyl groups on the surface of CDs@creatine interacted with the carbonyl groups of warfarin to form hydrogen bonds which rigidified the excited triplet against the non-radiative transition, and thus leading to their enhanced phosphorescence. Therefore, a dual-channel detecting strategy of warfarin has been successfully proposed with the fluorescent linear range from 8 × 10 −3 to 8 × 10 −7 M and phosphorescent linear range of 2 × 10 −5 to 1 × 10 −8 M, which established a new way of assaying warfarin. Besides, CDs@creatine served as both fluorescent and phosphorescent ink, and were applied for painting and information encryption.