Effects of nanocellulose on alginate/gelatin bio-inks for extrusion-based 3D printing

Abstract

Cellulose nanofibers (NFC) have attracted special attention in the field of extrusion-based three-dimensional (3D) bioprinting due to their good biocompatibility, excellent mechanical properties, and outstanding shear-thinning property. In this study, by mixing cellulose nanofibers suspension with sodium alginate (SA) and gelatin (GEL) solution, five groups of composite bio-inks with different NFC concentrations were prepared. The effects of NFC on the performance of the SA/GEL matrix hydrogels were analyzed by morphological observation, rheological property testing, mechanical property testing, swelling property testing, and printability analysis. The rheological results showed that the addition of NFC noticeably increased the viscosity of biological inks with low shear rates; therefore, the printed scaffolds maintained their structure better during the 3D printing process. After crosslinking with calcium chloride (CaCl2), the fidelity of the NFC/SA/GEL composite hydrogel structure was better than that of the SA/GEL hydrogel. Moreover, the structural properties were strengthened, and the mechanical stabilities of the composite hydrogels improved when NFC was added. Therefore, this study provided an easy way to improve the printability of extrusion-based 3D printing and the potential use of nanocellulose.

Preparation and Characterisation of Cellulose Nanocrystal/Alginate/Polyethylene Glycol Diacrylate (CNC/Alg/PEGDA) Hydrogel Using Double Network Crosslinking Technique for Bioprinting Application

“…This consistency suggests that the gelled formulations are able to retain their shapes with good shape fidelity post extrusion [37,38 It is important to note that bioinks with good shape fidelity will contribute to hig accuracy and resolution of a printed scaffold. This finding also corroborated that th addition of CNC has a positive effect on the shape fidelity of the gelled formulations probably due to the increased interactions between the hydrogel networks [16,18].…”

“…It is important to note that bioinks with good shape fidelity will contribute to high accuracy and resolution of a printed scaffold. This finding also corroborated that the addition of CNC has a positive effect on the shape fidelity of the gelled formulations, probably due to the increased interactions between the hydrogel networks [16,18]. Upon manual extrusion and double crosslinking treatment using ionic (Ca 2+ ) and UV irradiation at 365 nm, the physical characteristics of the CNC/Alg/PEGDA formulations were observed.…”

“…It is important to note that bioinks with good shape fidelity will contribute to high accuracy and resolution of a printed scaffold. This finding also corroborated that the addition of CNC has a positive effect on the shape fidelity of the gelled formulations, probably due to the increased interactions between the hydrogel networks [16,18]. On the other hand, the flow curve for F7 [4% Alg: 40% PEGDA] displayed shearthinning property even without the addition of CNCs.…”

“…In 3D bioprinting applications, CNCs are often used as rheological modifiers and reinforcing agents for hydrogels due to their high crystallinity [14]. Several studies report that the addition of nanocellulose greatly improved the printability of alginate-based hydrogels [16][17][18]. During the extrusion process, it was also reported that the printed structures not only retained their shape with minimal spreading but also had improved geometries [19,20].…”

Emerging Biofabrication Techniques: A Review on Natural Polymers for Biomedical Applications

“…Nanocellulose is derived principally from bacteria [163], and its use, combined with other bioinks, integrates the common properties of the cellulose: high stiffness, modulus, hydrophilicity, and thermal stability. For example, Han et al studied the effect of nanocellulose on alginate/gelatin bioinks [164]. Their result showed that the incorporation of a small amount of nanocellulose improved the printability, stability, and fidelity of the structure, but high amounts of nanocellulose promoted a negative impact on the elongation and compression yield.…”