"There's a lot of human-to-human variation regarding what counts as infected red blood cells versus some dust particles stuck on the plate. It really takes a lot of practice," he says.
The new SMART system detects a parasitic waste product called hemozoin. When the parasites infect red blood cells, they feed on the nutrient-rich hemoglobin carried by the cells. As hemoglobin breaks down, it releases iron, which can be toxic, so the parasite converts the iron into hemozoin a weakly paramagnetic crystallite.
Those crystals interfere with the normal magnetic spins of hydrogen atoms. When exposed to a powerful magnetic field, hydrogen atoms align their spins in the same direction. When a second, smaller field perturbs the atoms, they should all change their spins in synchrony but if another magnetic particle, such as hemozoin, is present, this synchrony is disrupted through a process called relaxation. The more magnetic particles are present, the more quickly the synchrony is disrupted.
"What we are trying to really measure is how the hydrogen's nuclear magnetic resonance is affected by the proximity of other magnetic particles," Han says.
For this study, the researchers used a 0.5-tesla magnet, much less expensive and powerful than the 2- or 3-tesla magnets typically required for MRI diagnostic imaging, which can cost up to $2 million. The current device prototype is small enough to sit on a table or lab bench, but the team is also working on a portable version that is about the size of a small electronic tablet.
After taking a blood sample and spinning it down to concentrate the red blood cells, the sample analysis takes less than a minute. Only about 10 microliters of blood is required, which can be obtained with a finger prick, making the procedure minimally invasive and much easier for health care workers than drawing blood intravenously.
"This system can be bu
|Contact: Sarah McDonnell|
Massachusetts Institute of Technology