Tip-Enhanced Raman Spectroscopy (TERS) for nanoscale imaging of biological membranes

Tip-enhanced Raman spectroscopy (TERS) is a label-free imaging technique that combines scanning probe microscopy with Raman spectroscopy to obtain local chemical information, well below the optical diffraction limit. Discovered in the early 2000s, it has now become the tool-of-choice for the nanoscale investigation of carbon-based materials and 2D polymers. The perspective of imaging biological samples is attractive, but it is largely hampered by their low Raman cross-section and by their tendency to degrade quickly under the TERS tip. In this work, we propose to overcome these obstacles using stable tips as well as an effective sample deposition method to achieve nanoscale spatial and chemical characterization of protein/lipid membranes. As model samples, biomimetic membranes and bacteriorhodopsin (BR) membrane (from Halobacterium Salinarum) are tested.