Table 3.

Toxicological evaluation of CNF-based materials.

Material	Preparation Method	Toxicological Experiment	Conclusion	Reference
Micro-fibrillated cellulose (MFC)	Fibrillating the fibres under high compression and shear forces.	Cytotoxicity evaluation with mouse macrophage and human monocyte	No evidence of cytotoxicity from the material nor the method.	[85]
Cotton cellulose nanofibres	Acid hydrolysis method	Cytotoxicity evaluation bovine fibroblast cells In-vitro effect on gene expression	Low cytotoxicity at low CNF concentration Reduction in cell viability and affection of expression of stress and apoptosis AMM at high concentration	[84]
Poly(vinyl alcohol)/cellulose nanofibril hybrid aerogel	Emulsification and freeze-drying processes	Cytotoxicity investigated with NIH 3T3 cells to explore their potential application as cell culture scaffolds.	Aerogel facilitates cell attachment, differentiation, and proliferation. Moreover, it was nontoxic and biocompatible	[90]
Cellulose nanofibril-based structures	Homogeniser without pre-treatment and with 2,2,6,6 tetramethylpiperidine-1-oxy radical	Cytotoxicity evaluation with 3T3 fibroblast cells	No toxic phenomena for pure CNF and slight toxicity for modified CNF	[86]
Cellulose nanofibres	Mechanical grinder preceded by mild chemical treatment	Cytotoxicity assays using a Vero cell lineage.	No cytotoxic behaviour of CNF or the method for direct and indirect assays	[87]
Cu/mesoporous bioactive glass/CNF membranes and aerogels	EISA method for MBGs, freeze-drying for membrane and solvent-exchange-freeze-drying for aerogel.	Cytotoxicity and biocompatibility evaluation in a 3T3 mouse fibroblast	Low cytotoxicity at low modified CNF concentration and no cell growth in high concentration	[88]
Cellulose nanofibres	Enzymatic hydrolysis method	The cytotoxicity of CNF assessed by MTT assay against three different cancer cell lines NCIH460, PA1, and L132 cells.	CNF did not show the cytotoxic effect at the tested concentrations in any of the cell lines.	[83]
Resveratrol-loaded cellulose aerogel	Freeze-drying method	Cytotoxicity to cartilage cells by the standard MTT assay	Low toxicity and good biocompatibility.	[91]