Ulvan structural modification enhances stability and cell compatibility of GelMa based bioinks for tissue engineering

The present study presents a novel structurally modified ulvan for gelatin methacryloyl (GelMa) based advanced biofabrication applications. Although ulvan and GelMa exhibit considerable potential as bio-inks for 3D printing, a solution stability issue within the composite formulation was identified in our previous work, which adversely affect both storage and printing process. To address this issue, an effective deproteinization method was initially developed to purify the ulvan extract and the purified ulvan was then modified with adipic dihydrazide (AD) and methacryloyl chloride to produce a photo cross-linkable macromer (UAMa). Methacrylated Ulvan (UMa) only was prepared as control. The ink solution formulated with UAMa and GelMa presented an enhanced solution stability and the photo cross-linked UAMa-based hydrogels (UAMaG) exhibited greater mechanical strength compared to the UMa-based hydrogels (UMaG). The composite was 3D printed to form scaffolds that demonstrated high cytocompatibility with primary human dermal fibroblasts. The enhanced performance highlighted the contribution of the hydrazine groups in modified ulvan. The results suggested that UAMa and its composite structures hold great potential as candidates for tissue engineering applications.