Creatine-based carbon dots with room-temperature phosphorescence employed for the dual-channel detection of 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 nonradiative 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 x 10-3 to 8 x 10-7 M and phosphorescent linear range of 2 x 10-5 to 1 x 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.

Automated summary

A strategy to synthesize phosphorus and nitrogen co-doped carbon dots using creatine as the carbon and nitrogen source was designed and implemented. The resultant carbon dots exhibited bright blue fluorescence in water and green RTP on filter paper. Introduction of warfarin quenched the fluorescence of CDs@creatine and enhanced their RTP, leading to a proposed dual-channel detecting strategy for warfarin.