Role of Triton X-100 in chemiluminescent enzyme immunoassays capable of diagnosing genetic disorders

The use of Triton X surfactants in developing 1,1'-oxalylimidazole chemiluminescent enzyme immunoassays (ODI CEIs) with extended linear response range for the quantification of unconjugated estriol (uE3), alpha-fetoprotein (AFP), and human chorionic gonadotropin (hCG) is reported for the first time. The wider linear dynamic range in ODI CLEIA results from Triton X series (e.g., Triton X-100, -114, -405, -705) acting as an inhibitor in the interaction between Amplex Red (hydrophobic substrate) and horseradish peroxidase (hydrophilic enzyme) to produce resorufin (hydrophobic fluorescent dye). Triton X-100 acts as the appropriate inhibitor in ODI CLEIA. The maximum concentrations of AFP and hCG quantified with sandwich ODI CLEIA in the presence of Triton X-100 were 8 times higher than when analyzed with the same system in the absence of Triton X-100. In addition, the lowest concentration of uE3 determined using competitive ODI CLEIA in the presence of Triton X-100 was 20 times lower than that measured with competitive ODI CLEIA in the absence of Triton X-100. These results indicate that rapid quantification of AFP, uE3, and hCG using cost effective and highly sensitive ODI CLEIAs in the presence of Triton X-100 can be applied as an accurate, precise, and reproducible method to diagnose genetic disorders (e.g., trisomy 18 and trisomy 21) in fetuses. (C) 2013 Elsevier B.V. All rights reserved.