Ultrasensitive Infrared Absorption Spectroscopy
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Ultrasensitive Infrared Absorption Spectroscopy

August 2, 2010
Engineered rod-shaped, gold nanoparticle arrays localize infrared light at the particle tips and dramatically enhance molecular specific absorption signals of protein molecules.

More about this Image By exploiting recent advances in nanophotonics and nanotechnology, a National Science Foundation-supported team of researchers, led by Hatice Altug of Boston University, has demonstrated an ultra-sensitive infrared (IR) absorption spectroscopy technique that can analyze minute amounts of proteins and other molecules. The technique may profoundly change the methodology of biomolecular studies and chart a new path to effective diagnostics and early treatment of complex diseases.

IR absorption spectroscopy uses infrared light to excite the bonds that connect atoms within molecules, causing the molecules to vibrate at a specific resonant frequency. By examining what frequencies of light are absorbed by the molecules, scientists can determine what type of bonds hold them together, and thus identify the molecule.

Because absorption signals are often weak, conventional IR spectroscopy requires large samples of target molecules in many layers. To overcome this limitation, the research team used arrays of tiny gold nanoparticles as highly efficient nano-antennas and amplified the signals of individual protein molecules more than 100,000 times. The team obtained vibrational signatures from bio-samples as thin as a single layer of protein. This advancement is fundamentally important for biochemistry, because it allows the sensitive study of molecular structures and biological functions of extremely small quantities of proteins. [Research supported by National Science Foundation grants SGER 08-49603 and CAREER 09-54790.] (Date of Image: May 2009)

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