Novel and facile synthesis of heparin sulfur quantum dots via oxygen acceleration for ratiometric sensing of uric acid in human serum

Abstract In this work, a novel kind of sulfur quantum dots (SQDs) is synthesized using heparin as passivator and stabilizer for the first time by simple treatment of sublimed sulfur and NaOH under a pure oxygen atmosphere. The obtained heparin SQDs (Hep-SQDs) show excitation-independent emission and have a high quantum yield (11.4%). Herein, we set up a ratiometric fluorescence probe based on the inner filter effect between Hep-SQDs and 2, 3-diaminophenazine, the oxidative product of o-phenylenediamine to detect uric acid (UA). The proposed probe is demonstrated to be highly selective and sensitive for UA assay with detection limit of 0.56 μM. Moreover, the established fluorescence probe is also successfully applied to the determination of UA in human serum. We hope this work can provide new opportunities for developing good performance fluorescent biosensors based on SQDs.