Pathogenic bacteria can lead to food poisoning and serious infectious diseases, and place a large burden on human health. A method for rapid capture and removal of the harmful bacteria from the contaminated source is essential and important. In this study, two types of amine group functionalized magnetic nanoparticles were successfully fabricated for effective capture of bacterial pathogens. These magnetic nanoparticles with a positive-charge surface strongly interacted with the negative-charge bacterial cell wall via electrostatic attractions to exhibit efficient adsorptive ability of a broad spectrum of bacterial pathogens. Owing to more cationic amine groups, the bacterial capture capacity of Fe3O4@sSiO2-PEI nanoparticles (PEI-MNPs) for E. coli BL21 was three times that of Fe3O4@sSiO2-NH2 nanoparticles (NH-MNPs), making them promising for practical applications. More importantly, the PEI-MNPs also showed excellent bacterial capture efficiency at a low concentration due to the multivalency effect that appeared in our system.
A novel magnetic solid-phase extraction (MSPE) method based on metal organic framework-801 (MOF-801) modified magnetic nanoparticles (noted as PEI-MNPs@MOF-801) was successfully prepared for the extraction of preterm labor treatment drugs (including indometacin, acemetacin and sulindac) from human plasma sample. MOF-801, a new kind of porous coordination polymer composed of Zr 4+ and fumaric acid, was modified on the surface of synthesized polyethyleneimine magnetic nanoparticles (PEI-MNPs) through amidation reaction. The obtained PEI-MNPs@MOF-801 was characterized with Fourier-transformed infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction and transmission electron microscopy. A MSPE-HPLC-UV method was developed by coupling PEI-MNPs@MOF-801 with HPLC system. Several parameters that affect the extraction efficiency including acetonitrile content, NaCl content, extraction time and sample volume were investigated. Under optimum conditions, the proposed MSPE-HPLC-UV method showed high extraction efficiency (enrichment factors between 96–118), good linearity with R ≥ 0.9987, excellent reproducibility (RSD ≤ 4.30 %) and low limits of detection in the range of 0.03−0.05 ng/mL. This method was also successfully applied to the extraction of indometacin, acemetacin and sulindac in human plasma samples and good recoveries were obtained.
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