High-Throughput Analysis of Bacterial Toxic Lipopolysaccharide in Water by Dual-Wavelength Monitoring Using a Ratiometric Fluorescent Chemosensor

Lipopolysaccharide (LPS) is a bacterial toxin that causesfeverin humans. Our small-molecule chemosensor named Zn-dpa-C2OPy shows rapid ratiometric fluorescence response to LPS in water witha detection limit of 11 pM, which is lower than that of our previouslyreported sensor. Spectroscopic measurements (fluorescence, absorbance, H-1 NMR, and fluorescence lifetime), dynamic light scatteringmeasurements, and transmission electron microscopy observations revealedthat the fluorescence response was induced by the changes in the aggregationstate via multi-point recognition of LPS through hydrophobic and electrostaticinteractions, in addition to the coordination between the zinc(II)-dipicolylaminemoiety of the chemosensor and the phosphate group of LPS. The proposed Zn-dpa-C2OPy chemosensor was applied to an original flow injectionanalysis (FIA) system with a self-developed dual-wavelength fluorophotometer,and a high throughput of 36 samples per hour was achieved. These resultsdemonstrate the feasibility of this unique methodology combining aratiometric fluorescent chemosensor and FIA for continuous onlinemonitoring of LPS in water.