Spectroscopic methods have greatly expanded our understanding of how biomolecules function and interact, as well as their structures. Vibrational spectroscopy is an analytical tool that can identify the composition and structure of biomolecules. When it comes to studying complex biological systems, however, bulk spectroscopy methods are hard to use because of how they retrieve information. For this reason, there is a need to be able to understand the chemical and structural properties of different molecular species, down to the scale of just a single molecule.
Current nanoscale spectroscopy is incredibly sensitive but still has been met with challenges when trying to quantify structural properties. A group of researchers used a combination of low power, short pulse and off-resonance nano spectroscopy (ORS-nanoIR) in order to detect the thermomechanical expansion and IR absorption of samples at the single protein molecule level
The scientists applied the ORS-nanoIR technique to get IR absorption spectra from individual protein molecules. Then they placed a probe on top of a single thyroglobulin molecule to find the acquisition of IR absorption spectra corresponding to amide bands I, II, and III. The amide I band is the one most commonly used to obtain the secondary structure of a protein.
In conclusion, the ORS-nanoIR methodology allows for the direct acquisition of absorption infrared spectra and can map a single protein molecule. This method expands the ability to observe and understand the chemical and structural properties of a single biomolecule. Developing this technique further and improving its sensitivity could yield several biomedical solutions.
The study is published in the journal, Nature Communications.