# Diversity of Potential (Bio)Technological Applications of Amino Acid-Based Ionic Liquids
## 2 Bioapplications of AA ILs: An Overview
### AA-ILs with Application in the Processing of Biomaterials
#### 2.6.1 Cellulose Treatment and Processing
Interestingly, when using a 100% concentration of [Ch][AA], the delignification time for rice straw (with a biomass-to-ionic liquid ratio of 50:1) was longer compared to reactions in a medium containing the same diluted IL [105]. However, the glucose and xylose yields from the subsequent enzymatic hydrolysis of the residue were not improved [94]. [PERSON] et al. demonstrated a 65% increase in lignin extractability from mulberry stems pretreated with [Ch][Gly] or [Ch][Ala] comparedto non-IL-pretreated controls [106]. Furthermore, lignin was readily recovered from the IL-containing media, with [Ch][Gly] yielding lignin with over 92% purity. In addition, the pretreatment increased glucose yield by 52-60% and xylose yield by 22-30% [106]. Notably, the [Ch][AAs] were not toxic to the bacterial strain _Actinobacillus succinogenes_, which was used as a whole-cell catalyst for subsequent succinic acid production via biomass fermentation [106]. Interestingly, the tensile strength of artificially aged paper pretreated with an aqueous solution of [Ch][Gly] was shown to be maintained [107]. This effect is attributed to the hydroxyl cross-linking of cellulose polymers mediated by the hydroxyl groups of choline and the amino groups of the AA anion of ILs [107]. In addition, [Ch][Arg] has the highest solubilizing capacity for pine, dissolving up to 19% of its mass. In contrast, [Ch][Gly] achieves only 9% solubilization but facilitates decomposition at significantly lower temperatures [108]. Although not as extensively studied as Ch-based ILs, AA-ILs with cations other than Ch have also been tested as media for the pretreatment of lignocellulosic biomass. For example, a previous study demonstrated that among various [Emim][AAs], [Emim][Gly] serves as a highly effective solvent for the delignignification of bamboo biomass, resulting in a significant reduction of about 85.3% in total lignin content [109]. Similarly, [PERSON] et al. reported that [Bmim][Trp], [Emim][Ala], and other ILs containing ammonium, phosphonium, or pyridinium cations with most amino acid anions do not significantly dissolve or do not dissolve microcrystalline cellulose [99]. However, N,N-diethyl-N-(2-methoxylyl)-N-methylammonium tryptophan ([N\({}_{221\text{ME}}\)][Trp]) was able to dissolve cellulose (5 wt%) at 100 \({}^{\circ}\)C [110]. A 23% dissolution of cellulose was achieved by stirring for 2 h at room temperature in a mixture of dry dimethylsulfoxide (DMSO) and [N\({}_{221\text{ME}}\)][Ala], while mixtures with DMF or CH\({}_{3}\)CN were less effective [111]. In contrast, mixtures of the IL with other co-solvents such as water, methanol, acetone, ethanol, CHCl\({}_{3}\), THF, dioxane, toluene, dichloromethane, or ethyl acetate were unable to dissolve cellulose [112]. In addition, [PERSON] et al. reported significant progress in the separation of cellulose, hemicellulose, and lignin from wood biomass using a simple procedure with N-methyl-N-(2-methoxylyl)-pyrrolidinium-2,6-diaminohexanoate lysine ([P\({}_{\text{IME}}\)][Lys]) [112]. This method can be used to obtain 0.131 g lignin, 0.665 g cellulose (type I), and 0.093 g hemicellulose from 1 g Japanese cedar (_Cryptomeria japonica_) [112]. Similarly, [PERSON] et al. reported an 18% (w/w) yield and simplified extraction of cellulose from moso bamboo (_Phylostachys heterocyclia_) powder using a [P\({}_{\text{1 ME}}\)][Lys]:DMF (1:1) mixture [113]. Notably, ILs are used not only in the pretreatment of raw biomass but also in various cellulosic processing steps. For example, pretreatment of wastewaterpaper with [Cys][NO\({}_{3}\)] effectively removed hemicellulose and CaCO\({}_{3}\)[114]. The resulting material was then used to produce char characterized by a unique morphology and high specific surface area (approximately 1011.21 m\({}^{2}\)/g). Compared to charcoal from non-IL-pretreated wastewater, it exhibited more than 40% higher capacity to extract Cd\({}^{2+}\), antibiotics, and bisphenol A from wastewater [114].