Cellulose nanofibers from lignocellulosic biomass of lemongrass using enzymatic hydrolysis: characterization and cytotoxicity assessment

The lemongrass (LG) leaves could be a useful source of cellulose after its oil extraction, which is still either dumped or burned, not considered as a cost-effective approach. The synthesis of cellulose nanofibers (CNF) from LG waste has emerged as a beneficial alternative in the value-added applications. The non-toxicity, biodegradability, and biocompatibility of CNF have raised the interest in its manufacturing. Method: In the present study, we have isolated and characterized CNFs using enzymatic hydrolysis. We also explored the cytotoxic properties of the final material. The obtained products were characterized using dynamic light scattering (DLS), fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), and thermogravimetric/differential thermal gravimetric analysis (TG/DTG). The cytotoxicity of CNF was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay against three different cancer cell lines NCIH460, PA1, and L132 cells.

Overall, the results concluded that LG waste-derived CNF is a potential sustainable material and could be employed as a favourable reinforcing agent or nanocarriers in diverse areas, mainly in food and drug delivery sectors. Graphical abstract Systematic representation of the synthesis of the cellulose nanofibers: The lignocellulosic waste of lemongrass (after oil extraction) was pretreated for the isolation of raw cellulose, followed by enzyme hydrolysis for the synthesis of pure cellulose nanofibers.

The FT-IR results showed that the resulting sample was of cellulose species, and CNF was found free from the non-cellulosic components like lignin and hemicellulose. The SEM micrographs of the cellulose showed a bundle like structure. The TEM micrographs of CNF showed diverse long fibers structure with 105.7 nm particle size analysed using DLS. The TGA analysis revealed that the thermal stability was slightly lower, compared to cellulose. Additionally, CNF did not show the cytotoxic effect at the tested concentrations (~10-1000 μg/ml) in any of the cell lines.