A novel Scanning Microwave Microscope for Quantitative and Tomographic Characterization in Physiological Applications
Progetto Scanning Probe Microscopes (SPM) sense short-range interactions between a scanning probe and a sample surface, providing information with atomic resolution. Among interactions, electromagnetic fields can be used, and in particular, microwaves interacting in the near field. The latter choice gives origin to the Scanning Microwave Microscopy (SMM). SMM allows performing quantitative measurements detecting local dielectric constant and conductivity, by measuring extremely small lossy capacitance (attofarad or less) while being able to penetrate optically opaque surfaces. Note that attofarad capacitance detected by low voltages corresponds to the measurement of a few elementary electron charges. Its label-free nanometric resolution, tomographic capabilities, and low invasiveness would candidate SMM as an ideal instrument for the functional characterization of cellular and subcellular structures. SMM could contribute to the understanding of pathophysiological processes, exploiting the relationship between spectroscopic electromagnetic properties and physiological processes. However, literature on biological application of SMM is extremely scarce -generally limited to dry (or just humid) and fixed samples-, and a significant amount of it has been produced by PI and his group. Scanning in a physiological environment is not easy for SPM in general, and extremely challenging for SMM. In this project, we propose to start from a new promising approach invented by the PI very recently (2019), the ‘inverted’ SMM (iSMM), potentially overcoming the limitations of existing SMMs. The aim of the proposed project is to develop, refine and verify the use of iSMM in biological applications including the analysis of the properties of cells and subcellular organelles in physiological conditions and the comparison of the results obtained from cells and organelles in different pathological and physiological state. This will require the development of iSMM for in-liquid operation, models of the interaction between microwaves and cells/sub-cellular structures in the physiological environment, introduction of new calibration techniques and investigation of pathophysiological processes. We will investigate living cells and subcellular structures (e.g. exosomes or mitochondria) looking at differences between samples from healthy control groups and from subjects with specific diseases (e.g. Chronic Fatigue Syndrome) or as a function of aging. In these conditions, we will focus on the analysis of human stem cells obtained by skeletal muscle, as well as their mitochondria and released exosomes.