Dual-responsive ratiometric luminescent assay for visual recognition of tetracyclines based on in situ encapsulation of Eu(III) and carbon dots into metal-organic frameworks

Abstract An efficient method of in situ self-assembly was utilized to encapsulate Eu3+ and carbon dots (CDs) within ZIF-8, creating a Eu3+/CDs@ZIF-8 dual-emissive ratiometric luminescent assay specifically designed for the recognition of tetracyclines (TCs). As the concentration of TCs rises, blue luminescence from CDs diminishes while red luminescence from Eu3+ intensifies. This mechanism, balancing 2 emissions, allows high-sensitivity detection of TCs in water and milk. TCs quench blue emission via inner filter effect and coordinate with Eu3+ to enhance red emission, causing a visible color shift. Consequently, the luminescence color of Eu3+/CDs@ZIF-8 can be visually observed to shift from blue to red. Furthermore, the developed luminescent test strip offers a portable and convenient solution for TCs detection, making it suitable for on-site analysis. The dual-emission self-calibration detection platform introduces a novel approach for the identification of TCs in food samples, providing a robust and reliable method for monitoring and ensuring environmental and food safety.