Ultrasensitive system of aptamer@β-CD-MOFs for the detection of Listeria monocytogenes by fluorescence method

This study introduces a rapid fluorescence-based detection method using a novel 5-FAM-labeled aptamer with high affinity for Listeria monocytogenes (L. monocytogenes), immobilized on β-cyclodextrin metal-organic frameworks (β-CD-MOFs). The system's specificity was tested against Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Salmonella typhimurium. Additionally, optimal performance was found at pH 7, with stable results maintained over 65 days. The 5-FAM-labeled aptamer binds to the β-CD-MOFs, generating fluorescence at 366 nm. Upon the presence of L. monocytogenes, the aptamer dissociates and binds to the bacteria, resulting in an increase in fluorescence at an excitation of 448 nm and an emission of 546 nm. The optimized system demonstrated a broad linear detection range from 4.6 to 4.6 × 10⁹ CFU/mL, with a limit of detection (LOD) of 3 CFU/mL. This system successfully detected L. monocytogenes in samples of tap water and red meat, underscoring its practical applicability for rapid bacterial detection.