Ratiometric fluorescence platform based on lanthanide-functionalized hybrid organic framework for sensitive detection of Salmonella enteritidis

The fluorescent hybrid, Ln-MOF/HOF, was prepared. • A rapid and sensitive strategy for Salmonella enteritidis detection was developed. • A wide linear range (10–10 8  CFU/mL) and low limit of detection (6 CFU/mL) were obtained. • The platform can be used in real food samples. The development of rapid and accurate methods of identifying foodborne pathogens is essential for ensuring food safety and protecting public health. We rationally constructed a lanthanide-functionalized organic framework heterostructure through an Ln 3+ -induced in situ partial transformation of a hydrogen-bonded organic framework (HOF) in which metal-organic framework (MOF) nanodomains were generated while preserving the original HOF skeleton. The resulting Ln-MOF/HOF composite integrates the structural stability and high surface accessibility of HOFs with the unique luminescent properties of lanthanide centers, enabling efficient fluorescence regulation and signal transduction. Based on this hybrid architecture, a ratiometric fluorescent aptasensor was developed to quantitatively identify Salmonella enterica via an aptamer-triggered competitive displacement strategy. Ligand-centered emission acted as the responsive signal, whereas Tb 3+ emission served as an internal reference, producing a self-calibrated “ON–OFF–ON” fluorescence response. Mechanistic investigations revealed that the sensing behavior was dominated by static quenching accompanied by dynamic aptamer redistribution between the material surface and target bacteria. A satisfactory linear relationship was obtained within the concentration interval of 10–10 8  CFU/mL, whereas the minimum detectable concentration reached 6 CFU/mL, with excellent selectivity, reproducibility, and environmental stability. Furthermore, satisfactory recoveries ranging from 93.0% to 103% were achieved in real food samples, demonstrating good practical applicability. Thus, the present study demonstrates an effective route for fabricating lanthanide-functionalized MOF/HOF heterostructures through partial framework conversion and establishes a self-referencing fluorescent sensing system for dependable pathogen analysis in complex food samples. Download: Download high-res image (126KB) Download: Download full-size image