A fluorogenic heterogeneous immunoassay for cardiac muscle troponin cTnI on a digital microfluidic device

Tsaloglou, Maria-Nefeli, Jacobs, Adrian and Morgan, Hywel (2014) A fluorogenic heterogeneous immunoassay for cardiac muscle troponin cTnI on a digital microfluidic device. Analytical and Bioanalytical Chemistry, 406 (24), 5967-5976. (doi:10.1007/s00216-014-7997-z).

Abstract

We describe a fluorogenic two-site noncompetitive heterogeneous immunoassay with magnetic beads on a low-voltage digital microfluidic platform using closed electrowetting-on-dielectric (EWOD). All the steps of an enzyme-linked immunosorbent assay (ELISA) were performed on the device using 9H-(1, 3-dichloro-9, 9-dimethylacridin-2-one-7-yl) phosphate as the fluorogenic substrate for the enzyme alkaline phosphatase. The performance of the system was demonstrated with cardiac marker Troponin I (cTnI) as a model analyte in phosphate-buffered saline samples. cTnI was detected within the diagnostically relevant range with a limit of detection of 2.0 ng/mL (CV?=?6.47 %). Washing of magnetic beads was achieved by movement through a narrow region of buffer bridging one drop to another with minimal fluid transfer. More than 90 % of the unbound reagents were removed after five washes. Further experiments testing human blood serum on the same platform demonstrated a sample-to-answer time at ?18.5 min detecting 6.79 ng/mL cTnI.

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Contributors

Author: Hywel Morgan

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