Affinity Capture of Uropathogenic Escherichia coli Using Pigeon Ovalbumin-Bound Fe3O4@Al2O3 Magnetic Nanoparticles

Escherichia coli and Staphylococcus saprophyticus are the most common causes of urinary tract infections, with 80% of these infections caused by uropathogenic E. coli. Because the P fimbriae of E. coli have specificity toward Gal(α1−4)Galβ units, pigeon ovalbumin (POA), whose structure contains terminal Gal(α1−4)Galβ moieties, was used as a probe for interaction with P fimbriated E. coli. The functional affinity probes for these bacteria by immobilizing POAa phosphoproteinonto the surface of magnetic iron oxide nanoparticles (NPs) coated with alumina (Fe3O4@Al2O3), using the phosphate units of POA as linking groups for the formation of phosphate−alumina complexes. The immobilization process occurred within 30 s when performing the reaction under microwave heating. The magnetic POA−Fe3O4@Al2O3 NPs generated using this facile approach exhibited specificity toward P fimbriated E. coli. The bacteria targeted by the affinity probes were characterized by matrix-assisted laser desorption/ionization mass spectrometry. The detection limit toward uropathogenic bacteria when using this approach was ∼9.60 × 104 cfu/mL (0.5 mL).