Modified paramagnetic beads in a microfluidic system for the determination of ethinylestradiol (EE2) in river water samples

NOELIA A. MARTÍNEZ; RUDOLF J. SCHNEIDER; GERMÁN A. MESSINA; JULIO RABA

BIOSENSORS & BIOELECTRONICS

ELSEVIER ADVANCED TECHNOLOGY

Año: 2010 vol. 25 p. 1376 - 1381

0956-5663

In this work, we have developed and characterized a novel microfluidic immunoassay methodology forrapid and sensitive quantification of ethinylestradiol (EE2) in river water samples. The detection of EE2was carried out using a competitive direct immunoassay method based on the use of anti-EE2 polyclonalantibodies immobilized on magnetic microspheres 3-aminopropyl-modified manipulated for an externalremovable magnet. The EE2 present in the water sample was allowed to compete with EE2-horseradishperoxidase (HPR) conjugated for the immobilized anti-EE2 antibody. The HPR, in the presence of hydrogenperoxide (H2O2) catalyzes the oxidation of catechol (Q) whose back electrochemical reduction wasdetected on gold electrode at 0.0 V. The response current obtained from the product of enzymatic reactionis inversely proportional to the amount of EE2 in the water sample. The electrochemical detection can bedone within 1 min and total assay time was 30 min. The calculated detection limits for electrochemicaldetection and the ELISA procedure are 0.09 and 0.32 ng L−1 respectively and the intra- and inter-assaycoefficients of variation were below 5.8%. Our electrochemical immunosensor showed higher sensitivityand lower time consumed than the standard spectrophotometric detection ELISA method, which showsthe potential for assessment of EE2 in river water samples.