Materials scientist Deborah Charych, chemist Jon Nagy, and colleagues at the Center for Advanced Materials who last year developed a thin film of molecules that changes from blue to red in the presence of influenza virus have succeeded in getting their molecules to form liposomes. Because the liposomes are much more stable than the thin films, they represent an important step towards the production of a simple diagnostic test that can be used at home.
In a report that first appeared in the Journal of the American Chemical Society and was described last week in the magazine Science, Charych and Nagy announced that they have been able to entice their molecules to self-assemble and link together to form liposomes, which are highly stabilized spherical particles. The thin-film that Charych and Nagy first produced was not practical because it quickly degraded.
The liposomes act as a single-step diagnostic because they are made up of two-part molecules. The first part, sialic acid, binds to receptors on the virus, changing the shape of the links that interconnect the second part, which consists of long hydrocarbon chains. The shape change alters the color of light reflected off the liposome from blue to red.
While the liposome assay is faster than current laboratory culture techniques, the LBL researchers acknowledge that it has a long way to go before it can be marketed. The sialic acid will bind to some bacteria in addition to flu virus, which means that it can yield false positive readings. Charych and Nagy want to replace the sialic acid with molecules such as antibodies that are more target specific. However, they are not yet at the stage where they can incorporate such large proteins into their liposomes.
Other researchers were quoted in Science as believing that the LBL team is headed in the right direction and that the process can be generalized to other types of home tests. Charych and Nagy are now investigating the design of similar tests for diagnosing sexually transmitted diseases.