Towards the 3D printing of innovative hydrogel scaffolds through vat polymerization techniques using methacrylated carboxymethylcellulose aqueous formulations

Two vat polymerization techniques were evaluated to print innovative hydrogel scaffolds for tissue engineering, from aqueous photo-crosslinkable formulations based on methacrylated carboxymethylcellulose (mCMC). A first formulation containing 2 wt% mCMC with a methacrylation degree (DM) of 34% and lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) as photoinitiator was specifically developed for digital light processing (DLP). Considering their viscoelastic properties measured by shear rheology, the DLP-printed hydrogels were proposed for soft-tissue repair. Interestingly, the swelling ratio and shape of the printed hydrogels were found to be preserved when immersed in a physiological environment. While DLP-printed hydrogels demonstrated impressive X- and Y-resolutions (85 µm), they were limited in producing hollow objects in the Z-direction. To address this limitation, the 3D printing of complex mCMC hydrogels through two-photon polymerization (TPP) was investigated for the first time, using a second formulation composed of 4 wt% mCMC (DM = 50%). 3D scaffolds with cavities of 30 µm were successfully printed with a resolution of 10 µm, paving the way for the design of scaffolds with controlled and precise structures, for soft-tissue engineering.