Physicochemical characterization of the SF hydrogel after incubation in PBS at 37°C for 3, 7 and 14 days.

<p>(a) XRD patterns of the SF hydrogels. (b) ATR-FTIR spectra of the SF hydrogels. (c) Schematic illustration of nanoscale IR spectroscopy using AFM-IR: IR pulses are emitted in the sample increasing the local absorption on SF nanofibrils acquired by the AFM cantilever tip, corresponding to the absorption spectroscopic peaks. (d) Tapping-mode AFM nano-images (10 μm x 10 μm), and (e) IR nano-spectra of the SF hydrogels obtained by measuring the samples at different points selected by the AFM tip, corresponding to the absorption spectroscopic signatures and indicated as green, blue and red points.