Highly efficient WS2 QD-based non-enzymatic fluorescent biosensor for ofloxacin and ciprofloxacin monitoring in aquatic media†

Quantum dot-based biosensors have gained prominence in recent times for the detection of biological and chemical hazards present in aquatic media which essentially contribute to the degradation of the environment and human health. Within this work, we demonstrate a WS₂ QD-induced turn-on fluorescent probe for specific monitoring of ofloxacin (OFL) and ciprofloxacin (CIP) residues in water. An efficient one-pot hydrothermal approach is applied for fluorescent water-soluble WS₂ QD preparation. The WS₂ QDs possess excellent photostability and monodispersity along with a superior shelf life. The WS₂ QDs interacting with FQns (OFL and CIP) showed a systematically enhanced fluorescence in varying FQn concentrations from 0 μM to 3 μM. Also, all the measurements showed excellent results for sensitivity along with superior specificity as well as anti-interference ability over other interfering substances like various metal ions and antibiotic derivatives. The proposed sensor allows the quantification of FQns in the range of 0–3 μM with the lowest detectable amount (LOD) of 0.08 μM and 0.06 μM and the minimal limit of quantification (LOQ) of 0.26 μM and 0.21 μM for both OFL and CIP, respectively, at natural pH. It achieved higher sensitivity than many established techniques and materials making up the gap of other existing systems in this range. We observed excellent results for the rapid in situ detection of FQns by implementing WS₂ QDs. The findings show potential for future use in real-time applications for FQns.