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.