AVS 50th International Symposium
    Biomaterial Interfaces Tuesday Sessions
       Session BI-TuP

Paper BI-TuP21
Detection of E. Coli O157:H7 with Surface Plasmon Resonance Biosensor in Complex Matrices

Tuesday, November 4, 2003, 5:30 pm, Room Hall A-C

Session: Poster Session
Presenter: A. Taylor, University of Washington
Authors: A. Taylor, University of Washington
Q. Yu, University of Washington
S. Jiang, University of Washington
Correspondent: Click to Email
There is an urgent need for fast, sensitive, and reliable methods for detecting biological warfare agents and food contaminants. Large analytes (i.e. Escherichia coli, Salmonella enteritidis, or Listeria monocytogenes) are difficult to detect and quantify at low concentrations without time-consuming amplifications (i.e. culturing and PCR). E. coli O157:H7, an important food contaminant, was detected with a surface plasmon resonance (SPR) biosensor. However, with amplification, the detection limit was 5x10@super 7@ cfu/ml. In this work, we detect E. coli in both buffer and complex matrices using a home-built SPR. Antibody specific to the O antigen protein expressed on the membrane of the E. coli cell was immobilized on sensing surface via self-assembled monolayers. Atomic force microscopy (AFM) is combined with SPR to optimize surface chemistries and antibody immobilization at the molecular level. Transport of large charged bacteria to the antibody functionalized surface is one important factor limiting the ability to detect low concentrations. Thus, we study the effects of flow rate and pattern on detection. The biosensor was proven to differentiate between E. coli strains O157:H7 and K12 based on the antibody chosen. Furthermore, immunomagnetic separation methods using antibody functionalized magnetic particles were used to separate analytes from complex matrices (i.e. ground beef). The objectives of this work are to improve low detection limit and to minimize non-specific binding for SPR detection of larger-sized analytes in complex matrices.