Food Biochemistry and Food Processing (2 edition)

(Steven Felgate) #1

BLBS102-c03 BLBS102-Simpson March 21, 2012 11:56 Trim: 276mm X 219mm Printer Name: Yet to Come


42 Part 1: Principles/Food Analysis

y y y


y y y y


y y y y


y y y y


y y


= Enzyme-labeled secondary antibody
= Enzyme-labeled analyte-specific
antibody
= Analyte-specific capture antibody

y


y


= Analyte

y


y


y= Analyte-specific antibodies


= Analyte

Direct sandwich assay Indirect sandwich assay

Figure 3.1.Sandwich ELISA with direct and indirect enzyme-labeled antibody detection.

Other techniques have been developed in recent years for
protein or allergen analysis, which utilize enzyme-labeled
antibodies for detection. These include lateral flow assays,
which are immunochromatographic tests involving movement
of immunoreactants along a test strip, and dipstick tests, which
involve immobilized capture antibodies on a test strip with an-
alyte detection by enzyme-labeled antibodies. Both techniques

are generally inexpensive, rapid, and portable, thus making them
ideal tools for online monitoring. For a detailed review of these
techniques and other methods for protein and allergen analysis,
the reader is referred to a recent review by Schubert-Ulrich et al.
(2009). The growing field of nanotechnology has opened up
other opportunities for development of enzyme-based biosen-
sors for protein analysis. A recent report captured the essence of

yy


y yyy


= Enzyme-labeled analyte

y


= Analyte-specific capture antibody

= Analyte

Direct competitive ELISA

y


y


y


y


y


y


y y


yy yy


y


y


= Analyte-specific
antibody

= Analyte

yy= Enzyme-labeled


secondary antibody

= Protein-bound
analyte

Indirect competitive ELISA

Figure 3.2.Competitive ELISA with direct and indirect enzyme-labeled antibody detection.
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