In the case of the two neutrally charged peptides, P11-2 (Q,0) and P11-7 (S,0), the lowest c* values were observed (14 μM and 110 μM, respectively) (Figure ). Notably, the reduction in attractive hydrogen bonding interactions between serine residues increases the c* for self-assembly. Despite the low c* values, neither system formed self-supporting hydrogels. This is consistent with our interpretation that long-range charge repulsion is required for gelation of these peptides.