Signal-on and selective detection of anti-tumor adjunctive drug zoledronic acid using fluorescent sulfur quantum dots

As a representative of the third generation of bisphosphonate drugs, zoledronic acid (ZA) is clinically used to treat osteolytic bone metastases from malignant tumors and osteoporosis. Herein, a novel signal-on strategy for highly selective detection of ZA is proposed, employing Fe 3+ -mediated fluorescent sulfur quantum dots (SQDs) as a probe. Specifically, Fe 3+ can induce the aggregation of SQDs in aqueous solution and strongly quench their fluorescence, however, which recovers again in the presence of ZA owing to its emulative complexation with Fe 3+ . The complex ratio and binding mode between ZA and Fe 3+ are also theoretically simulated. This method exhibits the merits of rapidness, high selectivity, reliability, and with no need of derivatization for ZA detection, with a detectable range of 5–200 μM and a detection limit of 1.7 μM. It has also been successfully applied to determine ZA in real samples including human serum, urine, and drugs.