Orange carbon dots for methylene blue detection in actual water samples, live cells and enoki mushroom

The prompt and accurate detection of methylene blue (MB), a harmful cationic dye, is crucial for environmental monitoring. This research involved the creation of orange fluorescent carbon dots (CDs), specifically tailored for MB identification. Utilizing fluorescence resonance energy transfer (FRET), the presence of MB significantly quenches the fluorescence intensity of CDs. Thus, CDs can detect MB with high selectivity, rapid response and enhanced sensitivity, achieving a low detection limit of 0.30 μM. Consequently, CDs proved to be effective tools for MB analysis in authentic aquatic environments and cellular contexts. We also developed a simple, portable detection system using a smartphone equipped with an RGB application, achieving a limit of detection (LOD) of 0.23 μM. Additionally, CDs have demonstrated effectiveness in detecting MB in enoki mushrooms. These findings highlight the future role of CDs as glorious optical sensing platform for pollutant detection and bioimaging.