Fig. 3.

a–e Histogram of elastic modulus and distribution functions for five chitosan hydrogels, varying their concentration C_p, DA and route of gelation assessed by AFM on their lateral surface (measurements performed at a depth between 0.5 and 2 mm from the surface). The red curve represents the nonparametric probability density function (NPPDF) using a kernel density estimation to smooth the histograms. f Comparison of the normalized elastic modulus occurrence corresponding to these five hydrogels