Figure 4.

Preparation of Fmoc-FF hydrogel using three variants of the classic pH-switch method employing HCl: (A) decrease in pH induced by the slow hydrolysis (≈18 h) of the glucono-δ-lactone (GdL) to gluconic acid; (B) the colloid method in which the hydrogel is obtained by a progressive colloid-to-hydrogel transition triggered by adding of Na₂CO₃ to the colloid solution; (C) decrease in pH allowed by the decomposition of the K₂S₂O₈ in oxygen gas and protons.