Non-Invasive Nanometer Resolution Assessment of Cell-Soft Hydrogel System Mechanical Properties by Scanning Ion Conductance Microscopy.

Biomimetic hydrogels have garnered increased interest due to their considerable potential for use in various fields, such as tissue engineering, 3D cell cultivation, and drug delivery. The primary challenge for applying hydrogels in tissue engineering is accurately evaluating their mechanical characteristics. In this context, we propose a method using scanning ion conductance microscopy (SICM) to determine the rigidity of living human breast cancer cells MCF-7 cells grown on a soft, self-assembled Fmoc-FF peptide hydrogel. Moreover, it is demonstrated that the map of Young's modulus distribution obtained by the SICM method allows for determining the core location. The Young's modules for MCF-7 cells decrease with the substrate stiffening, with values of 1050 Pa, 835 Pa, and 600 Pa measured on a Petri dish, Fmoc-FF hydrogel, and Fmoc-FF/chitosan hydrogel, respectively. A comparative analysis of the SICM results and the data obtained by atomic force microscopy was in good agreement, allowing for the use of a composite cell-substrate model (CoCS) to evaluate the 'soft substrate effect'. Using the CoCS model allowed us to conclude that the MCF-7 softening was due to the cells' mechanical properties variations due to cytoskeletal changes. This research provides immediate insights into changes in cell mechanical properties resulting from different soft scaffold substrates.