One-step synthesis of Fe-doped metal–organic framework nanozymes for colorimetric detection and removal of tetracycline antibiotics

In this work, ZIF-67/Fe nanozymes with specific binding sites toward tetracycline antibiotics (TCs) were synthesized via a one-step method, taking advantage of the strong interaction between Fe and oxygen-containing functional groups in TCs. Taking advantage of the specific enhancement effect of TCs on the peroxidase-like activity of ZIF-67/Fe, a high-performance colorimetric sensor array was constructed. This array could successfully discriminate four types of TCs, namely oxytetracycline, tetracycline, doxycycline, and doxycycline hydrochloride. It exhibited a linear detection range of 50–1000 μg L⁻¹ for all four antibiotics, with limits of detection (LOD) as low as 17.78, 19.71, 33.39, and 38.05 μg L⁻¹, respectively. Density functional theory (DFT) calculations revealed that Fe doping significantly enhanced the peroxidase-like activity of the nanozyme by facilitating electron transfer between the nanozyme and TCs. Furthermore, the ZIF-67/Fe nanozyme could effectively achieve TC removal after the detection process, and it still maintained the capability to accurately distinguish tetracycline antibiotics in real water samples. The one-step preparation strategy proposed in this study simplifies the synthesis process of MOF-based nanozymes. The constructed sensor array breaks through the technical bottleneck that traditional methods find it difficult to distinguish antibiotics of the same category. With the dual functions of high-sensitivity detection and pollutant removal, it provides a new idea for the accurate monitoring and control of TCs in aquatic environments.