In vitro degradation of in situ crosslinkable poly(propylene fumarate-co-ethylene glycol)-based macroporous hydrogels

The effect of crosslinking density and porosity on the degradation of macroporous hydrogels (MPHs) was evaluated in this study. MPHs were synthesized from aqueous solutions of poly(propylene fumarate-co-ethylene glycol) (P(PF-co-EG)) and poly(ethylene glycol)-diacrylate (PEG-DA) with concurrent free-radical initiation and pore formation reactions involving ammonium persulfate (APS), L-ascorbic acid (AH), and sodium bicarbonate (SB). The crosslinking density was controlled by the ratio of P(PF-co-EG):PEG-DA to obtain molecular weights between crosslinks (M_c) of 1000±100 and 1880±320 g/mol. Porosity was controlled by sodium bicarbonate and ascorbic acid concentrations and ranged between 78±2 and 89±3%. In vitro degradation was carried out in phosphate buffer saline (PBS) at 37°C and a pH of 7.4. MPHs degradation was assessed at 0, 2, 4, 8, and 12-weeks by evaluating the mass loss, volume change, elastic modulus under confined compression, and porosity via μCT. Both Mc and porosity had a significant effect on the modulus at the initial time-point. The Mc had the greatest effect on the degradation of these MPHs with percent mass loss up to 62±8% after 12 weeks.