Integrating AFM, raman, TERS, and complementary techniques for multiscale physical-chemical characterization in materials and life sciences

To understand the structural complexities in materials science and life sciences, such as structural, mechanical and chemical properties, it is essential to study their relationships on a nanometric scale to advance the applications of materials and the study of biological processes. This thesis presents a multi-analytical and multi-scale approach that integrates atomic force microscopy (AFM), Raman spectroscopy, tip-enhanced Raman spectroscopy (TERS) and related scanning electron microscopy (SEM) techniques, transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques in order to obtain a chemical-physical characterization of biological samples and materials. The first part of the work provides a detailed theoretical framework on how the techniques work, highlighting their operating principles, synergy and potential for integration. Subsequently, two representative case studies are discussed in two thematic sections. The first case addresses the chemical-physical characterization on a nanometric scale of extracellular vesicles derived from milk (mEVs), demonstrating how TERS allows, for the first time, the study of molecular heterogeneities present on a single vesicle, highlighting the different distributions of chemical bonds. The second case focuses on the multiscale characterization of laser-induced defects in the production of silicon heterojunction photovoltaic cells, showing how the integration of different techniques allows the morphological, mechanical and structural alterations caused by the laser itself to be highlighted. The results demonstrate that the use of a combined approach based on different techniques allows for a more in-depth understanding of the structure and optimization of its properties for future applications.