Preliminary results of combined scanning near-field optical microscopy and atomic force microscopy applied to a model biological system: Clostridium tyrobutyricum spores

Innovative microscopies for the measurements of biological parameters can be helpful to reduce environmental impact, to prevent food contamination and poisoning and to assess the biocompatibility of nano-materials. In this frame, we applied scanning nearfield optical microscopy (SNOM) and atomic force microscopy (AFM) to a model system constituted by Clostridium tyrobutyricum dormant spores and their vegetative cells. SNOM was used to acquire the information about optical properties of C. tyrobutyricum spores with sub-wavelength resolution. Comparing reflection and transmission SNOM images revealed the presence of structures inside the spores. A detailed topographic study of the spore�s external layers was carried out with AFM. To obtain information about the morphology of spores and vegetative cells at the nanoscale level, we applied AFM in the lateral force mode, that allowed us to have a qualitative picture of the elastic and viscoelastic properties of the spore coat.