Philips has developed new lab-on-chip technology, dubbed Magnotech, that utilizes magnetic nanoparticles that the company believes can lead to bedside immunoassay results as good as from the lab.
Integrated into a disposable biosensor cartridge that inserts into a hand-held analyzer, Magnotech uses magnetic nanoparticles to measure target molecules in very low (picomolar) concentrations in blood or saliva – in just a few minutes. The disposable cartridge automatically fills itself from a single drop of blood or saliva. Once filled, no other fluid movement is required. Currently, measuring very low concentrations of biomarkers for the diagnosis of disease (for example, cardiovascular disease) requires laboratory analysis, large sample volumes and a time-to-result delay of between 30 and 60 minutes.
The Philips’ Magnotech handheld technology has the potential to deliver:
Small sample volume (fingerpick drop of blood or saliva) Ease of use (potentially applicable for home testing) Multi-analyte (several analytes can be measured simultaneously, depending on the application) Lab-quality sensitivity Speed (measurement in 1-5 minutes depending on the application)
The underlying technology
The magnetic nanoparticles are preloaded into the cartridge during its manufacture and automatically disperse into the sample as the cartridge fills with saliva or blood. Coated with appropriate ligand molecules, the nanoparticles quickly bind to target molecules in the fluid sample.
An electromagnet situated under the cartridge brings the magnetic nanoparticles, including the captured target molecules, into contact with the active detection surface of the biosensor in order to achieve fast specific binding at this active surface. A second magnetic field then pulls any unbound magnetic nanoparticles away from the active surface, enabling measurement of the remaining target molecules. The measurement is done using an optical technique based on frustrated total internal reflection.
Philips has demonstrated proof-of-concept for its new biosensor technology in a variety of biological assays, including sandwich assays for the detection of cardiac Troponin I (cTnI) and parathyroid hormone (PTH), and inhibition assays to detect several drugs-of-abuse molecules (amongst others, morphine). Cardiac Troponin is a blood-borne protein that at elevated levels provides a useful biomarker for the diagnosis of myocardial infarction (heart attack). The morphine assay represents the first test of the technology in drugs-of-abuse testing.
During these proof-of-concept tests, Philips’ Magnotech technology was shown to speed up assays by a factor of more than 100 when compared to simply letting the nanoparticles diffuse to the sensor’s active surface. Furthermore, the technology improves ease of use by eliminating fluidic washing steps. With cTnI, the assay successfully detected minute (picomolar) concentrations in under five minutes.