Fluorescence ‘off–on’ probe for lead (II) detection based on Atractylodes III CQDs and bioimaging

In this work, a type of carbon quantum dots (CQDs) with bright blue emission was readily fabricated through one‐step hydrothermal treatment from Atractylodes III. We explored the surface morphology and optical properties of the CQDs using transmission electron microscopy, X‐ray diffraction patterns, X‐ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and ultraviolet–visible light spectrophotometry. The obtained CQDs possessed good photoluminescence properties, water solubility, and biocompatibility. The fluorescence quantum yield of these was 3.72%. It was found that the fluorescence intensity of CQDs was quenched by picric acid. After adding lead (II), the fluorescence could be effectively recovered. Therefore, an ‘off–on’ fluorescence probe was designed to detect lead (II) in the range 0–580 μM and the limit of detection was 0.068 μM. In addition, the experiments showed that the CQDs could be successfully used in bioimaging and as a hidden fluorescent ink. The surface morphology and optical properties of the obtained Atractylodes Ⅲ carbon quantum dots (CQDs) were investigated and the consequences revealed that they were spherical structure, accompanied by bright blue fluorescence and had good water solubility. In the range of 0‐410 μM, picric acid (PA) can effectively quench the fluorescence of the CQDs, after adding Lead (Ⅱ), the fluorescence can be effectively recovered and in the range of 0‐580 μM, the detection limit is 68 nM. The CQDs had been successfully applied to the determination of Lead (Ⅱ) in real water samples, bioimaging, and as fluorescence ink to hide and reveal information.