A fast intraoperative PTH point-of-care assay on the Philips handheld magnotech system.

BACKGROUND: Intraoperative parathyroid hormone (ioPTH) is used during minimally invasive parathyroidectomy (MIP) to predict the success of surgery and should be accurate with a short turnaround time. MATERIAL AND METHOD: We developed an ioPTH point-of-care (POC) assay on Philips handheld magnotech system. Magnotech technology is based on magnetically controlled movement of superparamagnetic nanoparticles in stationary sample fluid. During first phase, intact-PTH is captured by magnetic particles coated with anti-N-terminal-PTH antibodies. Subsequently, magnetic particles are collected by magnetic forces at sensor surface coated with anti-C-terminal-PTH antibodies. Unbound/nonspecifically bound particles are pulled away from detection surface, using a second magnetic force. Amount of specifically bound particles is measured using a surface-sensitive optical imaging technique. RESULTS: ioPTH test could be performed with a turnaround time of less than 10 min and could detect low intact-PTH concentrations (picomolar). Integrated cartridge contains a blood separation filter and dry reagents for the assay. CONCLUSION: The next magnotech ioPTH assay will be the only POC test able to give accurate results in less than 10 min, using 25 µL of whole blood. Thanks to the ease-of-use, magnotech ioPTH could be performed in the operating theater by any member of surgical staff.

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.