One of the big ideas behind biomarker development is not only to diagnose disease earlier and less invasively, but also to make it easier and cheaper for anybody to do. In the words of Boston University's Hatice Altug, diagnoses should be, ideally, "as cheap and easy as a pregnancy test," she tells nanotechweb.org. So, along the way to that goal, Altug and colleagues have developed a diagnostic test that enables cancer biomarkers to be seen with the naked eye.
Altug and her team built a prototype detector consisting of a light source and a nanostructured surface that detects presence of specific antibodies. They fabricated a plasmonic--or light-confining--surface patterned with segmented arrays of nanoscale holes. Then they coated each segment with a layer of proteins known to bind to specific antibodies. They engineered the arrays on the biosensor surface to produce "Fano" resonances, which would appear in a spectrometer as an upside-down, asymmetric script "V." When the right antibodies bind to the array, the resonance goes through a shift and the light drops. To the naked eye, the sensor turns dark, meaning the sought-after biomarker has been detected.
"When the biomolecules are captured by the proteins that recognize them, we can see with the naked eye antibody accumulation on the surface by looking at the intensity of the transmitted light," Altug said in a release. "This enables us to detect biomolecules without any labeling."
Altug published her research in the Proceedings of the National Academy of Sciences and is continuing to work on a device that seamlessly combines all elements. "It is really exciting to see a fundamental physical phenomenon such as Fano resonance behavior being directly applied to a real-world problem that can impact lives," said Ahmet Ali Yanik, the first author of the paper. "We now have a very strong foundation upon which increasingly more complicated, lab-on-chip systems can be constructed."