This review is focused on the fabrication, properties, and applications of hydrogels prepared from two of the most abundant biopolymers on earth, cellulose and chitin. The review emphasizes the latest developments in hydrogel preparation (including solvent systems, cross-linker types, and preparation methods, which determine the “greenness” of the process) using these biocompatible and biodegradable biopolymers. The preparation of both physical (without covalent cross-links) and chemical (with covalent cross-links) hydrogels via dissolution/gelation is discussed. Additionally, formation of injectable thermoset and/or pH sensitive hydrogels from aqueous solutions of derivatives (chitosan, methyl cellulose, and hydroxypropylmethyl cellulose) with or without a cross-linker are discussed. This review also compares the design parameters for different applications of various pure and composite hydrogels based on cellulose, chitin, or chitosan, including applications as controlled and targeted drug delivery systems, improved tissue engineering scaffolds, wound dressings, water purification sorbents, and others.

Biomass pretreatment using certain ionic liquids (ILs) is very efficient, generally producing a substrate that is amenable to saccharification with fermentable sugar yields approaching theoretical limits. Although promising, several challenges must be addressed before an IL pretreatment technology can become commercially viable. One of the most significant challenges is the affordable and scalable recovery and recycle of the IL itself. Pervaporation (PV) is a highly selective and scalable membrane separation process for quantitatively recovering volatile solutes or solvents directly from non-volatile solvents that could prove more versatile for IL dehydration. We evaluated a commercially available PV system for IL dehydration and recycling as part of an integrated IL pretreatment process using 1-ethyl-3-methylimidazolium acetate ([C2C1Im][OAc]) that has been proven to be very effective as a biomass pretreatment solvent. Separation factors as high as 1500 were observed. We demonstrate that >99.9 wt% [C2C1Im][OAc] can be recovered from aqueous solution (≤20 wt% IL) and recycled five times. A preliminary technoeconomic analysis validated the promising role of PV in improving overall biorefinery process economics, especially in the case where other IL recovery technologies might lead to significant losses. These findings establish the foundation for further development of PV as an effective method of recovering and recycling ILs using a commercially viable process technology.

Tuning the bioavailability of lidocaine was explored by its incorporation into the ionic liquid lidocainium docusate ([Lid][Doc]) and the deep eutectic Lidocaine·Ibuprofen (Lid·Ibu) and comparing the transdermal absorption of these with the crystalline salt lidocainium chloride ([Lid]Cl). Each form of lidocaine was dissolved in a vehicle cream and topically applied to Sprague–Dawley rats. The concentrations of the active pharmaceutical ingredients (APIs) in blood plasma were monitored over time as an indication of systemic absorption. The concentration of lidocaine in plasma varied between applied API-based creams, with faster and higher systemic absorption of the hydrogen bonded deep eutectic Lid·Ibu than the absorption of the salts [Lid]Cl or [Lid][Doc]. Interestingly, a differential transdermal absorption was observed between lidocaine and ibuprofen when Lid·Ibu was applied, possibly indicating different interactions with the tissue components.