Discovery of a fundamental class of solid matter with the atomic force microscope

O. Sahin
Columbia University,
United States

Keywords: atomic force, hydration, nanomechanics, biomaterial, water, spores


Atomic force microscopes (AFMs) are powerful tools to characterize the structure and properties of matter. Using a combination of AFM techniques including topographic imaging, nanomechanical cantilever sensors, force-distance curves, and frequency-dependent dynamic nanomechanical measurements, we investigated mechanical properties of the hygroscopic spores of a common soil bacterium. After encountering results that were difficult to rationalize with well-accepted mechanical models of solid matter, we developed a simple but radically different theory of matter based on the hydration force [1]. The theory not only provides explanation to several perplexing results, but also predicted highly unusual mechanical phenomena. Those predictions are also verified by AFM measurements. The findings indicate the existence of a fundamentally distinct class of matter that derives its mechanical properties from water [2] and there is a possibility that a large fraction of biological matter could belong to this class of matter that we named “hydration solids”. [1] Parsegian, V. A. & Zemb, T. Hydration forces: Observations, explanations, expectations, questions. Current Opinion in Colloid & Interface Science 16, 618-624 (2011). [2] Harrellson, S.G., DeLay, M.S., Chen, X. et al. Hydration solids. Nature 619, 500–505 (2023). doi: 10.1038/s41586-023-06144-y.