New Mini-Magnet Test Helps to Diagnose TB in Just 30 Minutes

by VR Sreeraman on Aug 10 2009 4:57 PM

It is now possible to diagnose tuberculosis (TB) in just 30 minutes, thanks to magnetic nanoparticles that can identify Mycobacterium tuberculosis in sputum, even at very low concentrations.

Their developer Ralph Weissleder, from Harvard Medical School, points out that the diagnosis of TB generally takes about two weeks because the bacteria is first spotted in sputum under a microscope, and then the suspect samples are sent away for confirmation.

That leads to a delay in treatment, and risks continued spread of the disease, points out the researcher.

Weissleder says that the new test gives the answer in half an hour.

A paper describing this test, published in the journal Angewandte Chemie, says that doctors can simply add the sputum to a solution containing nanoparticles with an iron core encased in iron oxide.

The report further says that each nanoparticle is loaded with antibodies that encourage any TB-causing bacteria in the sputum to bind to it

According to New Scientist magazine, the solution is fed through a lab-on-a-chip which blocks and concentrates the nanoparticles that have bacteria attached to them but lets the other nanoparticles through.

A small magnetic scanner encircling the chip then registers the presence of bacteria-laden nanoparticles.