Nuclear Fast Red-Stabilized Gold Nanoclusters and Their Application to the Detection of Chlortetracycline

As a high-efficiency antibiotic, chlortetracycline hydrochloride (CTC) is widely used, and its environmental residues pose a threat to human health. Therefore, the detection of CTC is of great significance. In this study, gold nanoclusters (AuNCs) were synthesized under certain conditions with Nuclear Fast Red as a stabilizer, chloroauric acid as the raw material, and sodium borohydride as the reducing agent. The synthesized AuNCs exhibited an optimal excitation wavelength of 376 nm and an optimal emission wavelength of 513 nm. It was observed that CTC could effectively enhance the fluorescence of the synthesized AuNCs at an emission wavelength of 424 nm when excited at 352 nm. The fluorescence intensity of the AuNCs system in the absence (F₀) and presence (F) of CTC was measured. A good linear relationship was observed between the fluorescence intensity enhancement value (ΔF = F–F₀) and the concentration of CTC in the range of 10.0–90.0 μM. The linear equation was ΔF = 8.67c + 123.5, with a limit of detection of 2.0 μM (3σ/k). Thus, AuNCs could be used as fluorescent probes for the detection of CTC concentration. The applicability of the method was validated using a spiked recovery test with river water samples. The recovery rates ranged from 94.0 to 103.4%, demonstrating the potential of this method for detecting CTC concentrations in river water samples.