Super-sensitive enzyme immunoassay for thyroid stimulating hormone using a new synergistic enhanced chemiluminescent endpoint.
The enhancers 1,1'-biphenyl-4-yl boronic acid and 4-iodophenol act synergistically in the horseradish peroxidase-catalysed oxidation of luminol. This concentration-dependent effect reduces background, increases signal and hence improves signal/background for detection of peroxidase. The same type of synergistic effect was found when 1,1'-biphenyl-4-yl boronic acid was added to a commercial enhanced chemiluminescence signal reagent (Amerlite Signal Reagent). This synergistic enhanced chemiluminescent endpoint (Amerlite Signal Reagent containing 1,1'-biphenyl-4-yl boronic acid) for a horseradish peroxidase label has been tested in the Amerlite TSH and the Amerlite TSH-30 Ultrasensitive assays. The detection limit (mean of 20 replicates of the zero standard+2SD) in the Amerlite TSH assay was 0.0029 mIU/L, and in the Amerlite TSH-30 Ultrasensitive assay the detection limit was 0.0005 mIU/L using the synergistic enhanced endpoint. Reassessment of the detection limit using a 1:40 dilution of the first standard (0.119 mIU/L) as the lowest assay standard gave a value of 0.0015 mIU/L for the Amerlite TSH-30 Ultrasensitive assay with the synergistic endpoint. A limited (n = 29) method comparison using samples from euthyroid, hyperthyroid and hypothyroid patients revealed excellent correlation between the conventional and synergistic TSH immunoassays.
Kricka
L J
LJ
Department of Pathology and Laboratory Medicine, University of Pennsylvania Medical Center, Philadelphia 19104, USA.
Ji
X
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D001897:Boronic Acids; D004357:Drug Synergism; D006735:Horseradish Peroxidase; D006801:Humans; D007124:Immunoenzyme Techniques; D007202:Indicators and Reagents; D007462:Iodobenzenes; D008163:Luminescent Measurements; D008165:Luminol; D010084:Oxidation-Reduction; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013972:Thyrotropin / Q000032:analysis*
D001897:Boronic Acids; D007202:Indicators and Reagents; D007462:Iodobenzenes; C103283:1,1'-biphenyl-4-yl-boronic acid; C050181:4-iodophenol; D008165:Luminol; D013972:Thyrotropin; D006735:Horseradish Peroxidase