CRP was identified from patients with acute pneumococcal pneumonia at the Rockefeller Institute for Medical Research (Tillett and Francis, 1930), a name that reflects its reaction with the C-polysaccharide of Pneumococcus. This pentameric protein with MW 118 kDa has five non-covalently bonded and non-glycosylated identical subunits of 206 amino acids each to form a disk-shaped pentagon (Fig. 1). CRP has been proven as an early indicator of infectious or inflammatory conditions as well as a universal biomarker for a wide range of diseases and disorders. As such diseases often commence at very low CRP levels, nM or even pM, analytical methods must be highly sensitive, selective, fast and reliable using minimum sample volume. Therefore, sensitive
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Capture anti-CRP Ab can be polyclonal from goat, sheep, rabbit, etc., and commercial sandwich ELISA kits comprise of capture anti-CRP Ab-bound microtiter plate (MTP) or Ab-bound 96-well plate strips for coating the MTP, apart from CRP standards, biotinylated anti-CRP detection Ab, and horseradish peroxidase (HRP) conjugated to streptavidin (SA-HRP). The commercial TMB (3,3 ',5,5 '-tetramethylbenzidine) substrate kit and the stop solution (strong acids) are also available. In brief, the enzymatic reaction of HRP with its TMB substrate to generate a resulting blue solution with absorbency measured at 450 nm vs 540 nm or 650 nm as reference. Most of the commercial kits are formulated for diluted human serum or plasma samples and tested for a numerous possible interferences from cytokines and other proteins.
Commercial benchtop or standalone analyzers are designed for low-, medium- and large-scale testing (Supplementary Information, Table S2). The medium-scale analyzers perform 90 samples in one run, based on the principle of turbidimetric IA (TIA) with only a few on sandwich IA, nephelometric and other IA formats. Such fully-automated analyzers process hundreds of CRP and others tests per hour and provide the result in about 30 min using serum or
Capture anti-CRP Ab can be polyclonal from goat, sheep, rabbit, etc., and commercial sandwich ELISA kits comprise of capture anti-CRP Ab-bound microtiter plate (MTP) or Ab-bound 96-well plate strips for coating the MTP, apart from CRP standards, biotinylated anti-CRP detection Ab, and horseradish peroxidase (HRP) conjugated to streptavidin (SA-HRP). The commercial TMB (3,3 ',5,5 '-tetramethylbenzidine) substrate kit and the stop solution (strong acids) are also available. In brief, the enzymatic reaction of HRP with its TMB substrate to generate a resulting blue solution with absorbency measured at 450 nm vs 540 nm or 650 nm as reference. Most of the commercial kits are formulated for diluted human serum or plasma samples and tested for a numerous possible interferences from cytokines and other proteins.
Commercial benchtop or standalone analyzers are designed for low-, medium- and large-scale testing (Supplementary Information, Table S2). The medium-scale analyzers perform 90 samples in one run, based on the principle of turbidimetric IA (TIA) with only a few on sandwich IA, nephelometric and other IA formats. Such fully-automated analyzers process hundreds of CRP and others tests per hour and provide the result in about 30 min using serum or