A fluorescent probe for selective detection of Fe3+ by using a self-assembled nitrogen-doped carbon quantum dots-3,4,9,10-perylenetetracarboxylic acid composite

We have synthesized nitrogen-doped carbon quantum dots (N-CQDs) via one-step hydrothermal method by using citric acid and urea as carbon sources, In order to solve the agglomeration effect of carbon quantum dots and increase its recognition sites, and then combined the N-CQDs with 3,4,9,10-perylenetetracarboxylic acid (PTCA) to synthesize an self-assembled carbon quantum dots-3,4,9,10-perylenetetracarboxylic acid (N-CQDs/PTCA) composite, which has strong fluorescent properties. The fluorescence spectrum showed that the prepared self-assembled composite (N-CQDs/PTCA) has strong yellow-green light emission near 510 nm. The characterizations such as ultraviolet–visible absorption, X-ray electron spectroscopy, Fourier infrared spectroscopy, and transmission electron microscopy have confirmed that the N-CQDs and PTCA were combined together successfully. And the prepared self-assembled N-CQDs/PTCA was independent of excitation. It has stable and strong fluorescence properties and can be used as a fluorescent probe. The study also found that in the presence of Fe 3+ ions, the fluorescence of self-assembled carbon quantum dots N-CQDs/PTCA will be quenched, and the quenching efficiency had a good linear relationship with the concentration of Fe 3+ ions. Therefore, we proposed to use the self-assembled carbon quantum dots N-CQDs/PTCA as a fluorescent probe to detect Fe 3+ selectively. The results showed that the method was fast, reliable, obvious detection signal, selective, and not affected by incubation time. The detection limit is 0.041 μM, which provides a new idea for the detection of Fe 3+ ions by using self-assembled method and has broad application prospects. Graphical abstract