Significant changes are also necessary for the modelling part 30. In terms of set-up, one needs to apply frequencies above the dielectric relaxation frequency of the electrolyte. As compared to the standard SDM in air, operation in liquid environment requires several modifications. In-liquid SDM is based on measuring the electrostatic force acting on a nanometric probe under application of a modulated voltage between the tip and a conductive substrate, on top of which the sample is sitting. The implementation of in-liquid Scanning Dielectric Microscopy (SDM) paved the way to the accurate dielectricĬharacterization of biomembranes at the nanoscale, in their physiological environment and in a label-free way 28, 29. Initially, these techniques were implemented to be operated in air environment, but lately they were also extended to liquid environment 28, 29. In recent years, the Nanoscale Bioelectric Characterization group at IBEC, as well as other groups, have developed some Scanning Probe Microscopies (SPMs) based techniques to attempt the dielectrical characterization at the nanoscale 12, 13, 14, 15, 16 andĪpplied them to biomembranes 17, 18, 19, 20, 21 and other biosystems 22, 12, 23, 24, 25, 26, 27. In other cases, they make use of exogenous labels, as in the case of spin paramagnetic resonance 5, 6 and fluorescence microscopy 7, 8, 9, 10, 11. Yet, most of the available techniques have addressed the dielectric membrane properties in bulk solutions and at the level of single cells (micrometers), thus lacking spatial resolution. However, biomembranes' dielectric properties are also of central interest in bioelectric phenomena, and a powerful reporter of membranes' composition, which can be exploited to develop label-free mapping methods. Most often, attention is paid to biomembranes' conduction properties, and the role played in them by ionic channels. Yet, there is still limited knowledge of biomembranes, which show a heterogeneous structure at the nanoscale that is naturally present in cells, and determines many of the phenomena occurring through them at the molecular level 3, 4.ĭue to their prominent role in Electrophysiology, electrical properties are among the more relevant physical properties of biomembranes. For this reason, biomembranes have been the subject of intensive research. The structure and physicochemical properties of biomembranes are fundamental for the functioning of cells, and many pathologies have been associated with their alteration (cancer, neurodegenerations, obesity, etc.) 1, 2.
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