An ultrasensitive immunoassay for prostate-specific antigen based on conventional colorimetric detection
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Published on: January 12, 2017
M J Khosravi1, A Papanastasiou-Diamandi, J Mistry
1Diagnostic Systems Laboratories (Canada) Inc., Toronto, Ontario.
Objective:
Development of an ultrasensitive immunoassay for serum PSA involving conventional detection probes.
Design And Methods:
The assay involves a polyclonal antibody immobilized in microtitration wells and a monoclonal antibody labeled with horseradish peroxidase. In a one-step assay, the enzymatic activity of the bound detection antibody is monitored by the addition of hydrogen peroxide/tetramethylbenzidine substrate reagent followed by spectrophotometric quantification of the conversion product.
Results:
The assay has a lower detection limit of 0.003 micrograms/L, biological detection limit of 0.009 micrograms/L, and intra- and interassay CVs of 8.2% and 10.5% at PSA concentrations of 0.022 and 0.065 micrograms/L, respectively. The recovery of the assay averaged 104% and it demonstrated a dilution linearity down to at least 0.01 micrograms of PSA/L. Results of comparison data correlated well with those obtained by a well established enzyme immunoassay. The serum PSA concentrations were < 0.012 micrograms/L in the majority of patients (53.8%) who had undergone radical prostatectomy.
Conclusions:
This assay is well suited for post-surgical monitoring of PSA in patients with prostate cancer.
