Biomimetic inks based on hemicellulose and nanocellulose for 3D printing

Three-dimensional (3D) printingsupplies a facile bottom-up approach allowing the patterning of biocompatiblehydrogels into 3D tissue-mimicking scaffolds towards biomedical application.Cellulose nanofibrils (CNFs) in the form of hydrogel with the outstandingproperties such as biocompatibility, in vitro biodegradability, flexibility,and excellent mechanical properties show a promising potential in mimicking thenative extracellular matrices (ECM). Thus, CNFs as an emerging platformmaterial in the ink formulation for 3D printing have attracted increasinginterest worldwide. In our study, we developed a surface-engineered biomimeticink formulation with CNFs and cross-linkable hemicellulose derivatives forUV-aided extrusion printing, being inspired by the intrinsic affinity ofhemicellulose to cellulose. A facile aqueous-based approach was firstlyestablished for the synthesis of a series of UV cross-linkablegalactoglucomanan methacrylates (GGMMAs) with tunable substitution degrees. Thechemical structures of GGMMAs were thoroughly characterized by NMR and sizeexclusion chromatography. The influence of methacrylation on the adsorption ofGGM to cellulose was studied with a quartz crystal microbalance to assess theadsorption level. The formulated inks showed a rapid gelation time windowverified by photo-rheology, which facilities the utilization of thesewood-based biopolymers as the feeding ink for the extrusion-based 3D printing.More significantly, a wide and tunable spectrum of different hydrogels withdifferent mechanical properties could be achieved by varying the substitutiondegree in GGMMA and the compositional ratio between GGMMA and CNF. Thesematerials show an excellent potential as a versatile culturing platform fordifferent cell lines.