Graphene quantum dots (GQDs) have been successfully used as a highly sensitive probe for the sensing of formaldehyde (HCHO) in an aqueous solution. Through static quenching, the probe utilizes the interaction between HCHO and GQDs to trigger the “turn off” fluorescence response, and has good selectivity. The probe can detect HCHO in a pure aqueous solution, and it also can still detect HCHO in a complex environment with a pH range from 4 to 10. The concentration of HCHO and the fluorescence intensity of GQDs show a good linear relationship within the range of HCHO of 0–1 μg/mL, which was much more sensitive than previous reports. The limit of HCHO detection by GQDs is about 0.0515 μg/mL. In addition, we successfully applied it to the actual food inspection. It is proved to be a selective, sensitive and visualized method to check whether the concentration of HCHO in the foods exceeds the regulatory limit, which presents a potential application in food safety testing.
Ultrasonic-assisted recycling of Nile tilapia fish scale biowaste into low-cost nano-hydroxyapatite: Ultrasonic-assisted adsorption for Hg2+ removal from aqueous solution followed by “turn-off” fluorescent sensor based on Hg2+-graphene quantum dots