Microfluidic Enzyme-Linked Immunosorbent Assay of Escherichia coli O157:H7 in Surface Enhanced Poly(methyl methacrylate) Microchannels

Keywords:
Escherichia coli O157:H7, surface modification, poly(ethyleneimine), poly(methyl methacrylate), ELISA, microfluidic

Abstract:
A novel surface treatment method was developed to enhance microchannel based ELISA for E. coli O157:H7 detection. By applying an amine bearing polymer, poly(ethyleneimine) (PEI), onto poly(methyl methacrylate) (PMMA) surface at pH higher than 11, PEI molecules were covalently attached and their functional amine groups were introduced to PMMA surface, which greatly improved the microchannel-based ELISA for E. coli O157:H7 detection. Compared with untreated PMMA microchannel, ~45 times higher signal and 3 times higher signal/noise ratio were achieved with the PEI surface treatment. Zeta potential analysis and X-ray photoelectron spectroscopy (XPS) demonstrated that alkali condition is preferable for PEI attachment onto the PMMA surface. High pH increased the surface zeta potential of the treated PMMA surface and the ELISA signal, indicating that more PEI molecules on PMMA surface facilitated antibody binding and ELISA detection. E. coli O157:H7 adsorption kinetics showed that as short as 2 minutes incubation time was sufficient for cells to bind to the microchannel surface, 1/120 of that required in 96-well plates. Also, the detection limit by the ELISA improved to 8 cells per sample in the PEI modified microchannel from 30 and 15 cells in 96-well plates and 384-well plates, respectively.

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Nanotech 2006 Conference Program Abstract