Facile synthesis of carbon dots from wheat straw for colorimetric and fluorescent detection of fluoride and cellular imaging

Colorimetric and fluorescent detection of F− have attracted enormous interest owing to their simplicity, low-cost and high selectivity. However, traditional colorimetric and fluorescent sensors mainly based on the insoluble and toxic organic molecules, which is not favorable for sensing F− in water media and living cells. In this work, we designed fluorescent carbon dots (CDs) with excellent water solubility and good biocompatibility as a colorimetric and fluorescent dual-model probe for the detection of F−. The CDs were prepared by a green, one-step hydrothermal strategy from wheat straw without any additives and surface passivation. The obtained CDs exhibited a bright blue fluorescence, special response to F− and low cytotoxicity. More interestingly, a significant color change from light yellow to red can be observed by the naked eye upon addition of F− ions to the CDs solution probably due to the formation of hydrogen bonding between CDs and F−. Besides, the fluorescence of CDs also can be selectively quenched by F− with the detection limit of about 49 μM. Additionally, the CDs are also applied to intracellular imaging and sensing of F− in living cells. This strategy may provide a new method for the detection of F− in water media and biological systems.