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. Author manuscript; available in PMC: 2018 Feb 1.
Published in final edited form as: Ann Biomed Eng. 2016 Apr 22;45(2):360–377. doi: 10.1007/s10439-016-1619-1

FIGURE 2.

FIGURE 2

Compression modulus (E5to15) and swelling ratio of photocrosslinked hydrogels. Error bars are standard error of the mean, and p<0.05 non-matching letters. (A)Stress verses strain for hydrogels loaded with uniaxial compression. (B–E) Compressive modulus of crosslinked hydrogels made with variable photoinitiator type, concentration and light source during crosslinking. These conditions were photocrosslinked under either a lamp or high powered LED array (HLED) for 5 minutes (2 or 136 mW/cm2). (B) E5to15 of hydrogels formed from precursor solutions prepared with three different concentrations of VA086 photoinitiator and crosslinked under a lamp for 5 minutes. One-way ANOVA with post-hoc Tukey-Kramer HSD (honest significant difference) test showed no significant between photoinitiator concentrations. (C) E5to15 of hydrogels formed from precursor solutions prepared with four different concentrations of Irgacure photoinitiator and crosslinked under a lamp for 5 minutes. One-way ANOVA with post-hoc Tukey-Kramer HSD test showed no significant between photoinitiator concentrations. (D) E5to15 of hydrogels formed from precursor solutions prepared with 0.1%w/v of Irgacure and crosslinked under a lamp or HLED for 5 minutes. One-way ANOVA with post-hoc Tukey-Kramer HSD test, p=0.0021 between lamp and HLED crosslinked conditions. (E) E5to15 of hydrogels formed from precursor solutions prepared with 1.0%w/v of VA086 and crosslinked under a lamp or HLED for 5 minutes. One-way ANOVA with post-hoc Tukey-Kramer HSD test, p<0.0001 between lamp and HLED crosslinked conditions. (B–E) Compressive modulus averages for the data shown are listed in Table S2. (F) Weight based swelling ratio (swollen weight divided by dry weight) of crosslinked hydrogels made with variable VA086 concentration and crosslinking light source. A two-way ANOVA showed no statistically significant interaction between the effect of VA086 concentration and the effect of light source on hydrogel swelling ratio (F=0.4151 p=0.4151), but both photoinitiator concentration and light source independently affect the swelling ratio. Results of Tukey HSD post-hoc test p<0.05 shown with non-matching letters. Average swelling ratios are listed in Table S3 and two-way ANOVA results are in Table S6. (G) Weight based swelling ratio of crosslinked hydrogels made with variable Irgacure concentration and light source during crosslinking. A two-way ANOVA showed no statistically significant interaction between the effect of Irgacure concentration and the effect of light source on hydrogel swelling ratio (F=0.1101 p=0.7428), but both photoinitiator concentration and light source independently affect the swelling ratio (two-way ANOVA results are in Table S7). Results of Tukey HSD post-hoc test p<0.05 shown with non-matching letters. (H) Compressive modulus versus swelling ratio of hydrogels.