Applications of biomass-derived solvents in biomass pretreatment - Strategies, challenges, and prospects.

Biomass pretreatment is considered a key step in the 2nd generation biofuel production from lignocellulosic biomass. Research on conventional biomass pretreatment solvents has mainly been focused on carbohydrate conversion efficiency, while their hazardousness and/or carbon intensity were not comprehensively considered. Recent sustainability issues request further consideration for eco-friendly and sustainable alternatives like biomass-derived solvents. Carbohydrate and lignin-derived solvents have been proposed and investigated as green alternatives in many biomass processes. In this review, the applications of different types of biomass pretreatment solvents, including organic, ionic liquid, and deep eutectic solvents, are thoroughly discussed. The role of water as a co-solvent in these pretreatment processes is also reviewed. Finally, current research challenges and prospects of utilizing biomass-derived pretreatment solvents for pretreatment are discussed. Given bioethanol's market potential and increasing public awareness about environmental concerns, it will be a priority adopting sustainable and green biomass pretreatment solvents in biorefinery.

In Vitro Evaluation of Lignin-Containing Nanocellulose.

The increasing importance of environmental sustainability has led to the development of new materials that are environmentally friendly, functional, and cost-effective. Lignin-containing cellulose nanomaterials are a common example of these. The advantages of lignocelluloses include their renewability, sustainability, and functionality combined with molecular rigidity and enhanced hydrophobicity. In order to valorize these beneficial traits from lignin-containing nanocellulose, various approaches have been examined in industrial applications. However, the safety of these materials has not been tested or validated in humans. In this study, we tested 21 wt% lignin-containing nanocellulose (L-MFC) in vitro using the human lung and kidney cell lines, H460 and HEK293 cells, respectively. The cytotoxicity of cellulose, L-MFC, and lignin was compared using the water-soluble tetrazolium salt assays. In addition, the gene expressions of HSP70 and HSP90 as cellular stress markers treated with cellulose, L-MFC, and lignin were quantified using real-time polymerase chain reaction (PCR) and Western blotting. Our data indicated little cytotoxicity for cellulose and significant cytotoxicity for lignin and a relatively low level of cytotoxicity for L-MFC, providing the lethal median concentration (LC50) values of L-MFC and lignin. The gene expression of HSP70 and HSP90 was little affected by moderate concentrations of L-MFC. Interestingly, the lignin contained in L-MFC influenced the cell viability and the gene expression of HSP70 and HSP90 less than the same amount of lignin alone. These results indicate that L-MFC displays cell-type-dependent sensitivity and suggest that L-MFC could serve as a new eco-friendly material that is relatively safe for humans.