Sawdust-derived cellulose nanofibrils with high biosafety for potential bioprinting

Abstract

Cellulose is a sustainable biopolymer with potential to reduce the adverse environmental impact of non-biodegradable plastics and promote a circular economy. Nanocellulose, a representative biobased nanomaterial, is considered as a promising material in biomedical applications due to its outstanding biocompatibility and low toxicity. However, the presence of some leachable immunogenic contaminants, such as endotoxin and (1,3)-β-D-glucan, in nanocellulose will often pose a potential risk in biomedical applications, particularly to the human body in 3D printing. In line with this challenge, a novel nanocellulose fabricating method was innovatively developed from the source of sawdust biomass to minimize the possible immunogenic contaminants presented in the cellulose nanofibrils (CNFs), which will ensure its biocompatibility of the material in applications. The resulting CNFs exhibited a very low level of leachable contaminants, recorded with endotoxin at 1.39 EU/g and (1,3)-β-D-glucan at 2.82 μg/g, respectively, which fall within the acceptable levels of Pharmacopoeia. In the following evaluation with the fabricated CNFs, the printability of the CNF hydrogel scaffolds was further optimized with hydrogel concentration at 5 %, printing pressure at 37 kPa, nozzle size setting up at 25 G, and crosslinker concentration at 200 mM, respectively. As an important property of 3D printed hydrogel scaffold, its biocompatibility was further evaluated and observed through cell culture in vitro, where the extract of hydrogel scaffold demonstrated a 36 % higher cell viability in promoting cell growth and proliferation when compared with that in pure culture medium. This exploration would suggest a possible application in the biomedical field that may not only secure a sound biocompatibility of CNFs produced from sawdust biomass, but also ensure the following 3D-printed scaffold with a viable cell growth and proliferation.