In general, P1 shows a lower tendency towards gelation compared to P2, due to the lack of the Fmoc moiety, which is known to enhance gelation via π-π stacking. At peptide concentrations of 1.9 wt% (19 mg mL -1 ) and pH ~7-7.4, only P2 (but not P1) hydrogels could be formed for both MQ and PBS solutions. With 0.5 equiv. of Zn(II), P1 hydrogels formed for MQ but not PBS solutions (Fig. , Table ). The presence of Zn(II) aids hydrogel formation via coordinative binding by the histidine moieties, but PBS may lower the effective Zn(II) concentration via phosphate binding, preventing hydrogel formation.