A Low-Field Magnetic Resonance Imaging Aptasensor for the Rapid and Visual Sensing of Pseudomonas aeruginosa in Food, Juice, and Water
2021
Jia, Fei | Bai, Xingjian | Zhang, Xiaowei | Fu, Yingchun | Li, Yanbin | Li, Xingmin | Kokini, Jozef L.
In this work, we present a low-field magnetic resonance imaging (LF-MRI) aptasensor based on the difference in magnetic behavior of two magnetic nanoparticles with diameters of 10 (MN₁₀) and 400 nm (MN₄₀₀) for the rapid detection of Pseudomonas aeruginosa (P. aeruginosa). First, specific anti-P. aeruginosa aptamers were covalently immobilized onto magnetic nanoparticles via 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide chemistry for the capture of the target bacteria. In the presence of P. aeruginosa, an MN₁₀–bacteria–MN₄₀₀ (MBM) complex was formed after binding between the aptamers on magnetic nanoparticles and P. aeruginosa cells. When a magnetic field was applied, the MBM complex and free MN₄₀₀ were rapidly magnetically separated, and free MN₁₀ left in the solution worked as a T₂ (transverse relaxation time) single readout in MRI measurement. Under optimum conditions, the LF-MRI platform provides both image analysis and quantitative detection of P. aeruginosa, with a detection limit of 100 cfu/mL. The feasibility and specificity of the aptasensor were demonstrated in detecting real food, orange juice, and drinking water samples and validated using plate counting methods.
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