Fig. 4.

Nanomechanical maps of the hydrogel and PDMS using Probe II in liquid. a–d PA Gel topography image, and the maps of indentation, contact stiffness and reduced elastic modulus. e Cross-section along the line shown in a. f–h Corresponding histograms obtained from b to d. i–l PDMS topography image, and the maps of indentation, contact stiffness and reduced elastic modulus. m Cross-section along the line shown in i. n–p Corresponding histograms obtained from j–l. The scale bars are 500 nm for the PA Gel and 1 μm for the PDMS sample