Self-Calibrating Dual-Emission Eu-MOF for Visual Detection of Dexamethasone Without Encapsulation or Functionalization

Abstract

Designing metal-organic frameworks (MOFs) with dual-state dual-emission properties is both rare and technically demanding. Despite this challenge, such materials hold immense potential for real-time sensing applications, offer exceptional stability, and provide intrinsic self-referencing mechanisms that effectively minimize background interference and enhance detection reliability. In this study, a novel Eu-based (Eu-MOF) is synthesized, demonstrating both liquid-phase and solid-state fluorescence. The as-prepared Eu-MOF exhibits a nano-spherical morphology and displays distinct dual emissions, blue (425 nm) and red (617 nm), under 250 nm excitation. A ratiometric sensing platform is established, leveraging the selective quenching of red fluorescence by Dexamethasone (DEX) while the blue emission remains nearly unaffected. This method enables a linear detection range of 8.0–222 µM with an impressive limit of detection of 0.34 µM. Furthermore, a smartphone-assisted visual detection approach is developed using RGB analysis via the Color Grab App, facilitating portable and on-site quantification. This intrinsic dual-emitting MOF eliminates the need for additional encapsulation or surface modifications, making it a highly stable, recyclable, and selective sensor with broad potential for real-world applications.