Selective probes for ferric ion: A highly fluorescent nitrogen-doped carbon quantum dots

Recently, carbon quantum dots (CQDs) is gaining more and more attention due to the possibility of its direct use in various fields of science and industry such as biomedical imaging, diagnostics and so on. In the paper, we successfully synthesized a nitrogen-doped carbon quantum dots (N-CQDs) with urea and o-phenylenediamine as raw materials by a facile and one-step hydrothermal method. The prepared N-CQDs was first used as fluorescent probe for the detection of iron(III) ion (Fe3+) and showed high selectivity and sensitivity. The detection mechanism of iron(III) ion (Fe3+) is further discussed. We assign the Fe3+ selectivity to the special coordinate interaction between Fe3+ and O,N of amide bond on the surface of N-CQDs. The detection limit was 39 nM. It showed excellent linear relationships in wide range from 8 × 10−7 to 2.6 × 10−6 M. The as-synthesized N-CQDs had been also successfully applied for cell imaging and detected Fe3+ in biosystem. It gave positive results when tested in both aqueous solution and living cells.