Colorimetric aptasensor for Listeria monocytogenes detection using dual functional Fe3O4@MIL-100(Fe) with magnetic separation and oxidase-like activities in food samples

A novel colorimetric aptasensor assay based on the excellent magnetic responsiveness and oxidase-like activity of Fe 3 O 4 @MIL-100(Fe) was developed. Fe 3 O 4 @MIL-100(Fe) absorbed with aptamer and blocked by BSA served as capture probe for selective isolation and enrichment of Listeria monocytogenes  one of the most common and dangerous foodborne pathogenic bacteria. The aptamer absorbed on Fe 3 O 4 @MIL-100(Fe) was further used as signal probe that specifically binds with target bacteria conjugation of capture probe for colorimetric detection of Listeria monocytogenes , taking advantages of its oxidase-like activity. The linear range of the detection of Listeria monocytogenes was from 10 2 to 10 7  CFU mL −1 , with the limit of detection as low as 14 CFU mL −1 . The approach also showed good feasibility for detection of Listeria monocytogenes in milk and meat samples. The spiked recoveries were in the range 81–114% with relative standard deviations ranging from 1.28 to 5.19%. Thus, this work provides an efficient, convenient, and practical tool for selective isolation and colorimetric detection of Listeria monocytogenes in food. Graphical Abstract