Nitrogen-doped quantum dots as high-efficiency nanoprobes for vanillin detection in complex samples and cell imaging applications

A new type of fluorescent nitrogen-doped carbon dots (N-CDs) were obtained by an economical, green, and feasible hydrothermal treatment using l-arginine and citric acid as carbon sources. The maximum value of the N-CDs fluorescence excitation/emission wavelength was 320/400 nm, showing an ultrahigh fluorescence quantum yield (51.7%). The fluorescence of N-CDs was effectively enhanced via vanillin, due to the combination of internal filtration effect and static polymerization. A fluorometric method was perfectly established for determining trace vanillin in serum, urine, biscuits, and vanillin tablet samples with a wide linear range of 0.0152–15.2 μg/mL, accompanied by the limit of detection is 4.56 ng/mL. Satisfactory recoveries were found to be range from 90.4% to 117%, with a relative standard deviation in the range of 1.5–7.9%. The prepared N-CDs were successfully used for A549 cell imaging. These results indicate that the newly developed and high-efficient nanoprobes N-CDs have great application potential in vanillin detection and cell imaging.