A highly stable, rapid and sensitive fluorescent probe for ciprofloxacin based on Al3+-enhanced fluorescence of gold nanoclusters

Fluoroquinolone antibiotics, especially ciprofloxacin (CIP), are commonly used in clinical practice as the antibacterial drugs. It is necessary to analyze CIP in biological media for studying its pharmacokinetics, further guiding correct medication. This paper reported Al3+ and gold nanoclusters (AuNCs) templated with glutathione for quantifying CIP with ratio-fluorescence analysis. Al3+ caused the aggregation of AuNCs that had the property of aggregation-induced emission, so the orange fluorescence of AuNCs was observed to sharply increase with Al3+ exposure. With adding CIP to coordinate with Al3+, AuNCs displayed decreased orange fluorescence due to the disaggregation, and the instinct blue fluorescence of CIP was also observed. The probe exhibited outstanding detection stability because of the ratiometric response, and could avoid the analyte-independent interference. It also displayed rapid response and excellent sensitivity during the detection of CIP. The response allowed to be completed within 1 min, and CIP even as low as 1.4 nM could be detected. Moreover, the application in urine revealed that the spiked recoveries of the probe were between 91.2 % and 103.6 %. Overall, this paper exploits a fluorescent probe for highly stable, rapid and sensitive determination of CIP through Al3+-enhanced fluorescence of AuNCs.