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United States Department of Agriculture

Agricultural Research Service


item Tu, Shu I
item Uknalis, Joseph
item Gore, Mitchell
item Irwin, Peter

Submitted to: American Chemical Society National Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 5/20/2004
Publication Date: 8/26/2004
Citation: Tu, S., Uknalis, J., Gore, M., Irwin, P.L. 2004. Dynamic factors controlling the pathogen capture by immuno magnetic beads. American Chemical Society National Meeting.

Interpretive Summary:

Technical Abstract: Biotinylated anti E. coli O157 antibodies were linked to streptavidin coated magnetic and polystyrene beads of different sizes and densities. These beads were then used to capture E. coli O157:H7. The captured bacteria were then further labeled by fluorescein-conjugated anti E. coli O157 antibodies. The complexes were then linked to urease-conjugated anti fluorescein antibodies further labeled bead-captured bacteria. The extent of the bacterial capture was related to the signal intensity of a light addressable potentiometric sensor (LAPS) that measured the pH changes associated with urease- catalyzed hydrolysis of urea. Under the conditions of applying the same amounts of biotinylated anti E. coli O157 antibody to beads, analyses of the capture kinetics indicated that heavier beads exhibited a better efficiency in capturing the target bacteria than that associated with the lighter beads of the same size. Furthermore, with the same density, larger beads diameters were more effective in capturing the bacteria. Since sedimentation volumes for the heavier and larger beads are greater than those of the lighter and smaller beads, more interactions with the target by the heavier and larger beads are expected. The observation is in agreement with a kinetic model that predicts the bacterial capture is controlled by the hydrodynamic motion of the beads.

Last Modified: 07/25/2017
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