A ratiometric fluorescent probe based on water-soluble CsPbX₃ (Br/I) perovskite nanocrystals for sensitive detection of tetracycline

A dual supersaturation recrystallization method was employed to synthesize water-stable, highly sensitive cesium-lead halide perovskite nanocrystals (CsPbBr₃ PNCs). The PNCs exhibited excellent water stability, a significant photoluminescence quantum efficiency of 83.03%, along with a narrow full width at half maximum (FWHM) of 20 nm. Following iodide ion treatment, the fluorescence emission peak of CsPbBr₃ PNCs can be tuned from 520 to 681 nm, causing a color transition from green to red. Within the 0–300 μM range, the red shift showed a linear correlation with I⁻ concentration, achieving a detection limit as low as 0.40 μM. It is worth noting that excessive iodide ions could have allowed PNCs to exhibit dual emission with maximum wavelengths of 520 and 681 nm. A ratiometric perovskite nanoprobe was constructed with the green emission peak as an internal standard and the red emission peak as the response signal. The probe demonstrated a strong linear correlation with tetracycline concentrations ranging from 0 to 8 μM, with a detection limit of 88.60 nM (S/N = 3). This research offers valuable insights into the design and development of ratiometric perovskite sensors capable of detecting in aqueous solutions, while also emphasizing the importance of rapidly establishing hydrogen-bonding networks when analyzing such detection systems.