Tip-enhanced Raman Scattering (TERS) is a spectroscopic technique that combines the advantages of surface-enhanced Raman scattering (SERS) with a scanning probe microscopy like AFM. This method joins the chemical information given by Raman spectroscopy with a physical sample information with imaging at spatial resolution on the nanometer scale. This work studies for the first time TERS spectroscopy for surface analysis of the Bacillus subtilis spore, which is considered as a model system for spore-forming bacteria. Special tips with Au nanoparticles with a diameter around 14 nm are used for TERS analysis. These tips are provided by NEXT-TIP, obtaining high-performance, reliable and stable TERS tips. The spectra exhibit significant point-to-point variations at the nanoscale. Therefore, AFM and TERS imaging maps can be correlated and discriminate the relevant chemical distribution of this complex biological system not easily identifiable. These results are useful for bacterial surface-display systems and for drug delivery applications.

G. Rusciano, G. Zito, R. Isticato, T. Sirec, E. Ricca, E. Bailo, A. Sasso, ACS Nano, 8 (2014) 12300. DOI: 0.1021/nn504595k.