Fabrication of nitrogen-enriched carbon dots with green fluorescence for enzyme-free detection of uric acid

Abstract

Nitrogen-enriched carbon dots (NCDs) with green fluorescence were prepared with an average diameter of 4.8 nm by a room temperature self-polymerization method using catechol and ethylenediamine as precursors. It was found that the green fluorescence of NCDs can be quenched directly by uric acid (UA). A facile and fast fluorescent enzyme-free sensor has been developed for the detection of UA in the linear concentration range of 0–30 μM, with a limit of detection of 0.22 μM. High sensitivity, stability and selectivity can also be achieved for the detection of UA. In addition, the mechanism of fluorescence quenching of NCDs induced by UA was the dynamic quenching type according to the linearity of the Stern–Volmer equation and the change of the lifetime of NCDs after adding UA. Furthermore, UA in saliva samples was successfully detected using this established fluorimetric method, showing the feasible detection of UA in complicated body fluid samples. This NCD-based fluorimetric non-invasive method can be used for the highly selective determination of UA in the clinical laboratory.