TABLE 1.

Tuning the vmIPN moduli to those of neural tissue

Weight % AAm	Weight % BIS	Swelling ratio	Measured elastic modulus (Pa) of swollen pAAm network (± SD) (n = 3)
10.0	0.300	1.11	9580 ± 767
10.0	0.150	1.18	5460 ± 290
5.00	0.200	1.10	902 ± 71
4.00	0.200	1.15	431 ± 26
3.00	0.100	1.25	97.8 ± 8
3.00	0.025	1.80	13.5 ± 1

By manipulating the concentration of monomers acrylamide (AAm) and bisacrylamide (BIS), poly(acrylamide) (pAAm) gels were synthesized to range in modulus from ∼10 to 10,000 Pa. These formulations were chosen to minimize the swelling ratio of these gels (Fig. 1 B). Polymerizations were conducted in 10-mL batches. The 10 weight % AAm formulations utilized 20 μL TEMED and 100 μL of 10 weight % AP, whereas all other formulations used 6 μL TEMED and 50 μL AP. Swelling ratio was calculated as the ratio of the diameter of the AAm network after >12 h of swelling in ultrapure water versus the diameter of the initial in situ polymerized diameter. Elastic modulus was determined through rheology (see Materials and Methods).