Facile preparation of highly thermosensitive N-doped carbon dots and their detection of temperature and 6-mercaotopurine

Carbon dots (CDs) have sparked immense interest because of their attractive optical properties in recent years, but the synthesis of multifunction CDs is still worth investigating. In this paper, a thermosensitive N-doped carbon dots (N-CDs) were prepared by facile hydrothermal method with sodium citrate and NH4Cl as raw materials. The N-CDs with a fluorescence quantum yield of 27.4% are excitation-independent, small size (1.34 nm), and good water-soluble. Importantly, the N-CDs display marvelous thermosensitive fluorescence response with good linear relationship, reversibility, and restorability in a range from 15 to 75 celcius, which can be applied to temperature sensing. Detailed characterization show that the thermosensitive fluorescence mechanism was the activation of nonradiative channels in higher temperatures. Besides, based on the inner filter effect (IFE), N-CDs could be served as a fluorescent probe for selective detection of 6-mercaptopurine (6-MP) without any modification or functionalization. The simple and efficient strategy for 6-MP sensing was quantified in a linear range of 1-90 mu M with a detection limit of 0.86 mu M and also can be applied to lake water and serum samples with satisfying recoveries.