RESUMO
A conventional colorimetric peroxidase end-point (ortho-phenylenediamine substrate), used in an enzyme immunoassay for carcinoembryonic antigen, employing plastic beads as solid support, has been replaced by a much faster (30 seconds versus 30 minutes) enhanced chemiluminescent assay for the peroxidase label. Para-iodophenol was used to enhance the light emission from the peroxidase catalysed chemiluminescent reaction between luminol and hydrogen peroxide. Values for precision and carcinoembryonic antigen concentration obtained with the chemiluminescent and colorimetric versions of the immunoassay on 62 serum specimens were in good agreement.
Assuntos
Antígeno Carcinoembrionário/análise , Técnicas Imunoenzimáticas , Medições Luminescentes , Antígeno Carcinoembrionário/normas , Estudos de Avaliação como Assunto , HumanosRESUMO
Certain phenol derivatives, including p-iodophenol and p-phenylphenol, enhance light emission from the horseradish peroxidase-catalyzed oxidation of cyclic diacyl hydrazides such as luminol. The light emission decays slowly (glowing for several minutes) and its intensity may be greater than 1000-fold that of the unenhanced reaction. The enhanced system enables rapid, sensitive assay of peroxidase conjugates. We describe its application in immunoassays for human choriogonadotropin, digoxin, and factor VIII-related antigen. Luminescent quantification of peroxidase labels has been directly incorporated into immunoassays based on beads, tubes, or microtiter plates, used in conjunction with photodetectors such as photomultiplier tubes or instant photographic film. Enhancement with phenol derivatives exceeds that achieved with 6-hydroxybenzothiazole derivatives and depends on pH and enhancer concentration. Emission spectra of phenol-enhanced and unenhanced reactions are remarkably similar, suggesting that the enhancers do not act as more efficient emitters but exert their action earlier in the complex reaction between peroxidase, oxidant, and luminol.
