Fig. 3. cryo-TEM images of 5% w/v hydrogels of FD, 25 mol% FD-RGD and FD-RGD (equivalent to 30, 28 and 22 mM, respectively). Scale bar = 200 nm. Fibrils average thickness based on image analysis (see ESI† S3) are ∼8 nm for FD and 25 mol% FD-RGD and ∼6 nm for FD-RGD. ESI S4† shows TEM images of 0.1 mM (0.02% w/v) solutions, as measured by CD above, demonstrating lower extent of fibrils that do not generate hydrogels.