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Rapid, high sensitivity, point-of-care test for cardiac troponin based on optomagnetic biosensor


These file attachments have been under embargo and were made available to the public after the embargo was lifted on 12 April 2010.

Author: Dittmer, W.U. · Evers, T.H. · Hardeman, W.M. · Huijnen-Keur, W.M. · Kamps, R. · De Kievit, P. · Neijzen, J.H.M. · Sijbers, M.J.J. · Nieuwenhuis, J.H. · Hefti, M.H. (Future Diagnostics) · Dekkers, D. (Future Diagnostics Wijchen) · Martens, M. (Future Diagnostics Wychen)
Embargo lifted:2010-04-12
Publisher: Elsevier
Institution: Philips Research
Source:Clinica Chimica Acta; authors version
Identifier: MS 30.231
Keywords: magnetic biosensor · point of care · sandwich immunoassays · troponin i (tni)
Rights: (c) Elsevier


BACKGROUND: We present a handheld integrated device based on a novel magnetic-optical technology for the sensitive detection of cardiactroponin I, a biomarker for the positive diagnosis of myocardial infarct, in a finger-prick blood sample. The test can be performed with a turn-around time of 5 minutes and can detect concentrations in the picomolar range in a sample volume of less than 25 L. METHOD: The test was completed in a compact, injection molded plasticdisposable with a 0.5 L assay chamber containing integrateddry magnetic nanoparticles and reagents. We have developed a 1-stepassay in which all reaction processes were precisely controlled bythe 3 electromagnetic coils positioned above and below the disposable. In the on-sensor assay, troponin molecules were sandwiched between capture antibodies attached to the detection surface and 500 nm superparamagnetic particles functionalized with tracer anti-troponinantibodies. Nanoparticles bound to the sensor surface were sensitively detected using the optical technique of frustrated total internalreflection (f-TIR). RESULT: A calibration function measured in 100%human plasma using our integrated test demonstrates a limit of detection (mean of blank plus 3 SD) of 0.03 ng/mL (1 pM) cTnI for a turn-around time of approximately 5 minutes. A linear regression analysis of the region 0.03-6.5 ng/mL yields a slope of 37 ± 4, intercept of 0.22±0.01 and linear correlation coefficient of R2=0.98. The measuring range could be extended substantially, to 100 ng/mL, by simultaneously imaging a second spot with lower capture antibody concentration. CONCLUSION: The combination of magnetic particles and their actuation with electromagnets permits the sensitive detection of cTnIto be performed rapidly. Because of the speed, ease-of-use and highanalytical sensitivity of the test, it is well suited for demandingpoint-of-care medical diagnostic applications.

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