Fig 2: Representative phase contrast images of DRGs cultured in CS hydrogels containing 100:1 EKR:NGF in the final culture study (scalebar = 0.25 mm). Arcs denotes the approximate neurite length in each image (A) CS, 100:1 EKR:NGF, 1 d; (B) CS, 100:1 EKR:NGF, 2 d; (C) CS, 100:1 EKR:NGF, 3 d; (D) CS, 100:1 EKR:NGF, 4 d.

Fig 3: Effect of C6S and NGF on cortical neuron outgrowth. Neurons were cultured on gels with and without C6S and/or NGF for 48 h. The average neurite length (A), maximum neurite length (B), and number of neurites (C) were determined for each gel composition. Mean ± SE, *p < 0.05 relative to PEG-BP, #p < 0.05 relative to PEG-BP-C6S, +p < 0.05 relative to PEG-BP-NGF.

Fig 4: Affinity-based NGF delivery from PEG-co-peptide CS system. Eight-arm PEG (black lines) are modified with bi-functional cross-linking peptides (dark gray dumbbells) on 6 arms and CS-binding peptides (light gray hexagons) on 2 arms. CS (striped stars) interacts with CS-binding peptides and NGF (spotted triangles).

Fig 5: HA gel DRG culture analysis. No statistical differences were observed; n = 14 for 100:1 EKR:NGF, and 16 for all other treatments. (A) Measured neurite length over time in 2% HA gels. (B) Growth rates of neurites, calculated by subtracting the neurite length of the previous day from the length of the current day.