N, S, I co-doped carbon dots for folic acid and temperature sensing and applied to cellular imaging.

The application of fluorescent carbon dots in bio-imaging has huge positive significance in the field of biomedicine. By taking this advantage, herein we prepared nitrogen, sulfur and iodine doped carbon dots (N,S,I-CDs) by a facile hydrothermal reaction using CNS, potassium iodate (KIO) and ethylenediamine (EDA), and the obtained N,S,I-CDs show bright blue fluorescence with a high fluorescence quantum yield of about 32.4%. The prepared N, S, I-CDs could interact with the folic acid (FA) with high selectivity, lead to development of a high sensitive method for the FA detection from 0.1 to 175 μM wide linear range with a detection limit of 84 nM (S/N = 3) and also applied them in U-2 OS cells imaging. Moreover, this sensor possessed a good sensitivity, linearity and reversibility in the temperature range of 10-80 °C, and successfully applied for the temperature sensing in cell HT-29 samples. This investigation illustrates that as-prepared N, S, I-CDs probe may have great potential as a high-performance platform for the accurate recognition of temperature in cells and could provide a new tool for the detection of FA in cells.