Food Biochemistry and Food Processing (2 edition)

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.