A water-stable formamidinium lead bromide perovskite nanocrystals@molecularly imprinted polymers fluorescent sensor for ultrasensitive detection of sulfadiazine

The widespread use of sulfadiazine (SDZ) in veterinary medicine and its subsequent accumulation in environmental waters necessitate the development of sensitive and selective monitoring tools. This study presents a novel hierarchical core-shell fluorescent nanocomposite, FAPbBr 3 PNCs@SiO 2 @MIP, for the ultrasensitive and selective detection of SDZ. The sensor was constructed by encapsulating water-sensitive formamidinium lead bromide perovskite nanocrystals (FAPbBr 3 PNCs) with a protective silica shell, followed by the grafting of a molecularly imprinted polymer (MIP) layer. The silica coating markedly improved the aqueous stability of the PNCs, while the MIP layer provided specific recognition cavities for SDZ, enabling detection through a photoinduced electron transfer-mediated fluorescence quenching mechanism. Under optimal conditions, the sensor demonstrated a wide linear response from 0.1 to 200 ng/mL and a remarkably low detection limit of 0.03 ng/mL. It also exhibited excellent selectivity against structurally analogous sulfonamides and common interfering ions (Imprinting factor is 3.9), along with high reproducibility and stability in complex media (94.3–100.9 % for the same batch, 98.9–101.4 % and 99.2–104.2 % for different batches). The practical applicability was validated through the successful detection of SDZ in real water and pork samples (Recovery was 99.2–112.0 %, RSD was 2.3–8.9 %), yielding results in good agreement with those from the standard liquid chromatography coupled with mass spectrometry (LC-MS) method. This work establishes a robust and reliable sensing platform for trace-level SDZ monitoring in environmental and food safety applications.