A novel two-in-one Eu-MOFs integrates electrochemiluminescence and ratiometric fluorescence dual-mode sensor for tetracycline detection.

Accurate detection of tetracycline residues is crucial for food safety and public health. Herein, a dual-mode electrochemiluminescence (ECL) and fluorescence (FL) sensing platform is developed based on Eu-MOFs constructed by coordinating 3-hydroxy-2-naphthoic acid (HNA) to Eu3+ nodes. This architecture confines HNA molecules within the framework, effectively suppressing aggregation-caused quenching and thereby enhancing ECL output. Meanwhile, the distinct emission bands of Eu3+ and HNA enable ratiometric FL readout, achieving dual-mode sensing functionality. To further increase accessible active sites, a P123 soft template is introduced to regulate crystal growth and morphological evolution, yielding a flower-like Eu-HNA-P123 structure. Compared with Eu-HNA, this material exhibits more accessible active sites and improved electron transfer properties, resulting in a significantly enhanced ECL response. Further, a molecularly imprinted polymer (MIP) is deposited on the surface of Eu-HNA-P123 to construct the Eu-HNA-P123@MIP composite, endowing the system with specific recognition capability. Consequently, a dual-mode ECL/FL sensing platform based on two-in-one sensing probe enables efficient and reliable detection of tetracycline, with RGB analysis further demonstrating its potential for real-time and visual detection. Overall, this work integrates dual-mode sensing functionality into a single probe through independent signal response mechanisms, offering a feasible new strategy for food safety monitoring.