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Escherichia coli with autodisplayed Z-domain of protein A for signal amplification of SPR biosensor.

Abstract
Generally, an immunoaffinity SPR biosensor detects a target analyte in a sample through highly selective adsorption by using the antigen-antibody interaction. For improving the sensitivity, various kinds of particles have been added to the already bound analytes on the SPR biosensor (sandwich assay). In this work, signal amplification was demonstrated by the expression of the IgG-binding Z-domain of protein A on the outer membrane of Escherichia coli via "Autodisplay". The amount of Z-domain of protein A expressed on the outer membrane was calculated to be 280,000 molecules per cell. In addition, the IgG-binding ability of the expressed protein was characterized using FACS analysis. The signal amplification of the SPR biosensor was performed in the sandwich assay format using a model of horseradish peroxidase (HRP); the limit of detection was determined to be significantly improved from 1 microg/ml to 1 ng/ml. Finally, myoglobin analysis was demonstrated for the medical diagnosis of cardiac diseases. The detection limit was estimated to be improved from 10 ng/ml to <1 ng/ml. These results show that Z-domain-displaying E. coli can be successfully used for the signal amplification of immunoaffinity biosensors, thereby improving the sensitivity and the limit of detection.
AuthorsJoachim Jose, Ji-Won Chung, Byoung-Jin Jeon, Ruth Maria Maas, Chang-Hoon Nam, Jae-Chul Pyun
JournalBiosensors & bioelectronics (Biosens Bioelectron) Vol. 24 Issue 5 Pg. 1324-9 (Jan 01 2009) ISSN: 1873-4235 [Electronic] England
PMID19036573 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
Chemical References
  • Immunoglobulin G
  • Staphylococcal Protein A
Topics
  • Biological Assay (instrumentation)
  • Biosensing Techniques (instrumentation, methods)
  • Equipment Design
  • Equipment Failure Analysis
  • Escherichia coli (drug effects, genetics, metabolism)
  • Immunoassay (instrumentation)
  • Immunoglobulin G (analysis, metabolism)
  • Protein Engineering (methods)
  • Protein Structure, Tertiary
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Staphylococcal Protein A (genetics, metabolism)
  • Surface Plasmon Resonance (instrumentation)

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