Nitrogen-doped carbon dots a fluorescent probe for detection of <i>p</i>-hydroxybenzaldehyde and cell imaging

As one of the main ingredients in the traditional Chinese medicine Gastrodia elata, p-hydroxybenzaldehyde (PHBA) has many pharmacological effects. Therefore, the monitoring of PHBA level is of great significance to exact valuation of the pharmacokinetics and toxic effect of PHBA in body fluids. In order to achieve the sensitive detection of PHBA, nitrogen-doped carbon dots (NCDs) have been designed. NCDs were successfully prepared through a hydrothermal strategy with chrysanthemum as the precursor. The transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction pattern were used for the characterization of NCDs. The as-prepared NCDs showed bright fluorescence with excitation/emission maxima of 290/421 nm and exhibited a fluorescence quenching response to PHBA under the optimal conditions. A good linear response was constructed at the PHBA concentration, ranging 10.0–150.0 μM with a detection limit of 63 nM based on the mechanisms of static quenching and inner filter effect. The proposed probe has been successfully applied to the detection of PHBA in blood and urine samples. In addition, the as-prepared NCDs with good biocompatibility were utilized for cell imaging. These results suggested that NCDs were promising probes for biosensing and bioimaging.