Rapid, high sensitivity, point-of-care test for cardiac troponin based on optomagnetic biosensor.
BACKGROUND
We present a prototype handheld device based on a newly developed optomagnetic technology for the sensitive detection of cardiac troponin I (cTnI) in a finger-prick blood sample with a turnaround time of 5 min.


METHODS
The test was completed in a compact plastic disposable with on-board dry reagents and superparamagnetic nanoparticles. In our one-step assay, all reaction processes were precisely controlled using electromagnets positioned above and below the disposable. Nanoparticle labels (500 nm) bound to the sensor surface via a sandwich immunoassay were detected using the optical technique of frustrated total internal reflection.


RESULTS
A calibration function measured in plasma demonstrates a limit of detection (mean of blank plus 3-fold the standard deviation) of 0.03 ng/mL cTnI. A linear regression analysis of the region 0.03-6.5 ng/mL yields a slope of 37+/-4, and a 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 a lower antibody concentration.


CONCLUSIONS
The combination of magnetic particles and their fine actuation with electromagnets permits the rapid and sensitive detection of cTnI. Because of the potential high analytical performance and ease-of-use of the test, it is well suited for demanding point-of-care diagnostic applications.
Dittmer
Wendy U
WU
Philips Corporate Technologies, Eindhoven, The Netherlands. wendy.dittmer@philips.com
Evers
Toon H
TH
Hardeman
Willie M
WM
Huijnen
Willeke
W
Kamps
Rick
R
de Kievit
Peggy
P
Neijzen
Jaap H M
JH
Nieuwenhuis
Jeroen H
JH
Sijbers
Mara J J
MJ
Dekkers
Dave W C
DW
Hefti
Marco H
MH
Martens
Mike F W C
MF
D015374:Biosensing Techniques / Q000379:methods / Q000592:standards*; D006801:Humans; D008280:Magnetics; D019095:Point-of-Care Systems / Q000592:standards*; D012680:Sensitivity and Specificity; D013997:Time Factors; D019210:Troponin I / Q000032:analysis / Q000097:blood*
D019210:Troponin I