Dissolution assay of FD and FD-RGD mixed peptide hydrogels. Both FD and FD-RGD were prepared as 5% w/v stock solutions from which mixtures were prepared. Peptide and calcium concentrations were measured post 72 hours of incubation (n = 5, see ESI Table 1).

Hydrogel type mol%	Mol% peptide in hydrogels	Mol% Ca2+ in hydrogels	Anionic residues in hydrogel/Ca2+ mol ratio
FD	97	105a	8.1
10% FD-RGD	97	103	8.3
15% FD-RGD	97	101	8.4
25% FD-RGD	97	100	7.9
40% FD-RGD	99	97	7.8
FD-RGD	99	85	7.6

^aThe concentration after incubation is higher than the initial since there is adsorption of Ca²⁺ ions from the medium.