Biomimetic Inks Based on Cellulose Nanofibrils and Cross-Linkable Xylans for 3D Printing

Abstract

This paper presents a sustainable all-wood-based ink which can be used for 3D printing of constructs for a large variety of applications such as clothes, furniture, electronics, and health care products with a customized design and versatile gel properties. The 3D printing technologies where the material is dispensed in the form of liquids, so called inks, have proven suitable for 3D printing dispersions of cellulose nanofibrils (CNFs) because of their unique shear thinning properties. In this study, novel inks were developed with a biomimetic approach where the structural properties of cellulose and the cross-linking function of hemicelluloses that are found in the plant cell wall were utilized. The CNF was mixed with xylan, a hemicellulose extracted from spruce, to introduce cross-linking properties which are essential for the final stability of the printed ink. For xylan to be cross-linkable, it was functionalized with tyramine at different degrees. Evaluation of different ink compositions by rheology measurements and 3D printing tests showed that the degree of tyramine substitution and the ratio of CNFs to xylan-tyramine in the prepared inks influenced the printability and cross-linking density. Both two-layered gridded structures and more complex 3D constructs were printed. Similarly to conventional composites, the interactions between the components and their miscibility are important for the stability of the printed and cross-linked ink. Thus, the influence of tyramine on the adsorption of xylan to cellulose was studied with a quartz crystal microbalance to verify that the functionalization had little influence on xylan's adsorption to cellulose. Utilizing xylan-tyramine in the CNF dispersions resulted in all-wood-based inks which after 3D printing can be cross-linked to form freestanding gels while at the same time, the excellent printing properties of CNFs remain intact.

Three-Dimensional Printing of Wood-Derived Biopolymers: A Review Focused on Biomedical Applications

“… 129 , 130 This has inspired the utilization of hemicellulose derivatives as promoting agents in the 3D printing of nanocelluloses, which offer a cross-linking network by binding with the cellulose matrix in the woody bioink. As demonstrated by Markstedt et al, 95 tyramine-modified xylan acts as both a fiber surface modifier and a biodegradable cross-linker in the formulation of nanocellulose bioinks.…”

“…Similarly, xylan modified with tyramine groups was integrated with CNFs in the formulated bioink. 95 The cross-linking proceeded within seconds in the presence of both horseradish peroxidase and H 2 O 2 . Most importantly, the strong affinity between xylan and CNF is beneficial for the ink compatibility.…”

Stimuli-Responsive Polymer Systems—Recent Manufacturing Techniques and Applications

“…Helpful for improving cells viability [57] iii. Excellent shape fidelity [58] i. iii. Supports cell adhesion, migration, proliferation [59] i.…”

Progressive 3D Printing Technology and Its Application in Medical Materials

“…3D printing technology has been widely applied in a variety of industries including aviation (Wong, 2016), geoscience (Ishutov et al, 2018), education (Smith and Jones, 2018), clothing (Markstedt et al, 2017), medical (Mitsouras et al, 2015;Giannopoulos et al, 2016), and pharmaceuticals (Orsi et al, 2015;Norman et al, 2017;Trenfield et al, 2018). Among these medical and pharmaceutical industries, orthopedic and dental applications are favorable to embrace the 3D printing technology (MarketsandMarkets, 2019).…”