A startup called T2 Biosystems is developing a test that uses magnetic nanoparticles to detect blood-borne infections in hours—compared to the days it now takes using conventional lab methods. The company's first device—about the size of a printer—will target Candida, a fungus that is the third-most-common cause of hospital-acquired infections. The detection system can identify Candida in human blood samples in about two hours. Clinical trials involving samples from actual patients are in the works.
The sooner a hospital lab can identify the cause of a patient's infection, the faster that patient can be put on the right antibiotics. Today, microbiologists often try to grow the infectious agent in the lab and run various tests to identify it. This can take a few days, and some organisms, including Candida, grow more slowly than others. Tests based on amplifying genetic material are considerably faster, but require complicated processing equipment. Tests that use fluorescent labels to light up a target are also faster, but samples like blood are too cloudy for the light to pass through.
T2 Biosystems's technology is based on work carried out by researchers at MIT, Harvard, and Massachusetts General Hospital on tailoring iron-oxide nanoparticles to bind to specific biomarkers, and then using a miniature magnetic system to detect the binding. The detector is essentially a tiny, simplified version of a nuclear magnetic resonance imaging system. Such systems usually require very large, expensive magnets, whereas T2 Biosystems's device uses a magnetic detector about the size of a penny.
Company founder and MIT materials science professor Michael Cima says there are two main advantages to the magnetic particle approach: magnetic fields can travel through blood and other media that light can't penetrate, and the magnetic detection system is very sensitive—so it can tell clinicians precisely how much of a particular pathogen is present.