title: Rapid, high sensitivity, point-of-care test for cardiac troponin based on optomagnetic biosensor.
abstract: 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.
authors.affiliation: Philips Corporate Technologies, Eindhoven, The Netherlands. wendy.dittmer@philips.com
authors.forename: Wendy U
authors.initials: WU
authors.lastname: Dittmer
authors.forename: Toon H
authors.initials: TH
authors.lastname: Evers
authors.forename: Willie M
authors.initials: WM
authors.lastname: Hardeman
authors.forename: Willeke
authors.initials: W
authors.lastname: Huijnen
authors.forename: Rick
authors.initials: R
authors.lastname: Kamps
authors.forename: Peggy
authors.initials: P
authors.lastname: de Kievit
authors.forename: Jaap H M
authors.initials: JH
authors.lastname: Neijzen
authors.forename: Jeroen H
authors.initials: JH
authors.lastname: Nieuwenhuis
authors.forename: Mara J J
authors.initials: MJ
authors.lastname: Sijbers
authors.forename: Dave W C
authors.initials: DW
authors.lastname: Dekkers
authors.forename: Marco H
authors.initials: MH
authors.lastname: Hefti
authors.forename: Mike F W C
authors.initials: MF
authors.lastname: Martens
mesh_terms: 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*
chemical_list: D019210:Troponin I