Francesco Simone Ruggeri, University of Camebridge, UK

Biological processes rely on a wide class of biomolecular and macromolecular machines whose function emerges from their chemical and structural properties and have characteristic nanoscale physical dimensions. In order to shed light on the rules of life, on dynamic biomolecular processes, on the biophysical properties of individual biomolecules and living organisms, it is crucial to access chemical and structural information at the nanoscale under relevant physiological conditions. Several imaging techniques working beyond the diffraction limit of light have been developed to visualize biological samples at the nanoscale, such as atomic force microscopy (AFM) and electron microscopy. However, imaging microscopies are to the most part chemically blind. Mapping a single property at the time, such as morphology or stiffness, is not sufficient when studying inhomogeneous and complex biological systems, such as biomolecules, cells and living organisms.

Here, we show the application of infrared nanospectroscopy (AFM-IR) as a real breakthrough for the analysis of heterogeneous biological samples at the nanoscale. AFM-IR is a versatile technique to study biomolecular processes with nanoscale chemical resolution bridging multiple biological scales. The technique is capable to provide simultaneously information on the morphology, mechanical, chemical and structural properties of single proteins, their interaction and self-assembly. It is possible to scale up our approach to study the methylation state of liquid-liquid phase separate protein condensates and single chromosomes. As well as, we demonstrate to expand the in vitro approach to characterize the structural properties of protein in living organisms, such as bacteria and archaea, single neurons and C. Elegans worm models of neurodegeneration. Finally, as a major advance in the field, we prove that infrared nanospectroscopy can successfully unravel the chemical properties of biological samples at the nanoscale not only in air, but also in native liquid environment that is of fundamental importance to study biomolecular processes and organisms.