MIT chemical engineers have developed a novel way to generate nanoparticles that can recognize specific molecules, opening up a new approach to building durable sensors for many different compounds, among other applications.
The new polymer-based sensors offer a synthetic design approach to the production of molecular recognition sites—enabling, among other applications, the detection of a potentially infinite library of targets.
To create these "synthetic antibodies," the researchers used carbon nanotubes—hollow, nanometer-thick cylinders made of carbon that naturally fluoresce when exposed to laser light. In the past, researchers have exploited this phenomenon to create sensors by coating the nanotubes with molecules, such as natural antibodies, that bind to a particular target. When the target is encountered, the carbon nanotube's fluorescence brightens or dims.
The MIT team found that they could create novel sensors by coating the nanotubes with specifically designed amphiphilic polymers—polymers that are drawn to both oil and water, like soap. This approach offers a huge array of recognition sites specific to different targets, and could be used to create sensors to monitor diseases such as cancer, inflammation, or diabetes in living systems.
"This new technique gives us an unprecedented ability to recognize any target molecule by screening nanotube-polymer complexes to create synthetic analogs to antibody function," says Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT and senior author of the study, which appears in the Nov. 24, 2013 edition of Nature Nanotechnology.
Moreover, this approach can provide a more durable alternative to coating sensors such as carbon nanotubes with actual antibodies, which can break down inside living cells and tissues. Another family of commonly used recognition molecules are DNA aptamers, which are short pieces of DNA that interact with specific targets, depending on the aptamer sequence. However, there are not aptamers specific to many of molecules that one might want to detect, Strano says.