The toxicity of some promising biomass-dissolving amidinium-, imidazolium-, and phosphonium-based ionic liquids (ILs), toward two different cell lines, human corneal epithelial cells and Escherichia coli bacterial cells, was investigated. In addition, dynamic light scattering (DLS) and ζ potential measurements were used to study the effect of the ILs on the size and surface charge of some model liposomes. Capillary electrophoresis (CE) was used for determination of the electrophoretic mobilities of the liposomes and for determination of the critical micelle concentration (cmc) of the ILs. The toxicity of the phosphonium ILs was highly dependent on the longest linear chain of the IL, due to increasing hydrophobicity, with the long-chain phosphonium ILs being toxic while the shorter-chain versions were significantly less toxic or not toxic at all. Amidinium and imidazolium ILs showed no significant effect on the cells, within the concentration range used. Moreover, the more hydrophobic ILs were found to have a major effect on the surface charges and size distributions of the model liposomes, which can lead to disruption of the lipid bilayer. This indicates that the cytotoxicity is at least to some extent dependent on direct interactions between ILs and the biomembrane.

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The adsorption of anionic phospholipids on silica was investigated by the dissipative quartz crystal microbalance (QCM) technique. Liposomes composed of 1 mM 80:20 mol % of 1-palmitoyl-2-oleyl-sn-glycero-3-phosphatidylcholine (POPC)/phosphatidic acid, POPC/phosphatidylglycerol, or POPC/phosphatidylserine in N-(2-hydroxyethyl)piperazine-N'-(2-ethanesulfonic acid) buffer at pH 7.4 (with or without 3 mM of CaCl2) were examined. We have previously demonstrated that similar phospholipid coatings can be used in capillary electrochromatography as a stationary phase for the separation of analytes. In this work, we focus on the formation of the coatings and on the type of lipid structure formed on silica. The QCM investigation comprised qualitative results based on changes in frequency and resistance, and quantitative modeling of the obtained results. The latter was performed using the dissipative QCM, which measures the quartz crystal impedance, combined with equivalent circuit analysis. A previously developed coating and cleaning procedure for phospholipid-coated fused silica capillaries was adopted in this study, and the same silica-coated crystal was used throughout the QCM study. We will demonstrate in this work that the type of lipid structure formed on silica, that is, a rather rigid supported lipid bilayer or a viscoelastic supported vesicle layer (SVL), is highly dependent on the lipid and solvent composition. We also show for the first time that the modeling of the dissipative QCM data can be used to extract a more quantitative picture of an adsorbed SVL, because, so far, published studies have merely used the QCM data in a qualitative sense.

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Coating of colloidal lignin particles (CLPs), or lignin nanoparticles (LNPs), with proteins was investigated in order to establish a safe, self-assembly-mediated modification technique to tune their surface chemistry. Gelatin and poly-L-lysine formed the most pronounced protein corona on the CLP surface, as determined by dynamic light scattering (DLS) and zeta potential measurements. Spherical morphology of individual protein coated CLPs was confirmed by transmission electron (TEM) and atomic force (AFM) microscopy. A mechanistic adsorption study with several random coiled and globular model proteins was carried out using quartz crystal microbalance with dissipation monitoring (QCM-D). The three-dimensional (3D) protein fold structure and certain amino acid interactions were highly dependent on the protein adsorption on the lignin surface. The main driving forces of protein-lignin affinity were electrostatic, hydrophobic, and Van der Waals interactions, and hydrogen bonding. The relative contributions of these interactions were highly dependent on the ionic strength of the surrounding medium. Capillary electrophoresis (CE) and Fourier transform infrared spectroscopy (FTIR) provided further evidence about the adsorption-enhancing role of specific amino acid residues such as serine and proline. These results have high impact on the utilization of lignin as colloidal particles in 2 biomedicine and biodegradable materials, as the protein corona enables tailoring of the CLP surface chemistry for intended applications.

The effect of 11 common amidinium, imidazolium, and phosphonium based ionic liquids (ILs) on zebrafish (Danio rerio) and Chinese hamster ovary cells (CHO) was investigated with specific emphasis on the effect of anion and cation chain length and aggregation of phosphonium based ILs. Viability and behavioral alteration in the locomotor activity and place preference, after IL treatment of 5 days postfertilization larvae, was recorded. Behavior and histological damage evaluation was performed for adult fish in order to get insight into the long-term effects of two potential biomass-dissolving ILs, [DBNH][OAc] and [P4441][OAc]. To get an understanding of how IL aggregation is linked to the toxicity of ILs, median effective concentrations (EC50) and critical micelle concentrations (CMC) were determined. The long-chain ILs were significantly more toxic than the short-chain ones, and the anion chain length was shown to be less significant than the cation chain length when assessing the impact of ILs on the viability of the organisms. Furthermore, most of the ILs were as monomers when the EC50 was reached. In addition, the ILs used in the long-term tests showed no significant effect on the zebrafish behavior, breeding, or histology, within the used concentration range.

Ioncell® is a Lyocell-based technology for production of man-made cellulose fibres. This technology exploits the intrinsic dissolution power of superbase-based ionic liquids (ILs) towards cellulose. The regenerated fibres are produced via a dry-jet wet spinning process, in which the cellulose filaments are stretched in an air gap before regenerating in an aqueous coagulation medium. In order to commercialize this process, it is essential to prove the techno-economic feasibility of this technology. That said, many important criteria are to be met, among them selecting a solvent with high cellulose dissolution power, proving a stable spinning process and yielding fibres of good mechanical properties. Most of all, it is critical to demonstrate the recovery of the solvent from the coagulation bath without impairing its solvation power. This study reports on the spinnability and recyclability of the IL 7-methyl-1,5,7-triazabicyclo[4.4.0] dec-5-enium acetate ([mTBDH][OAc]) over five cycles in comparison to 1,5-diaza-bicyclo[4.3.0]non-5-enium acetate ([DBNH][OAc]). The ILs were recovered from the coagulation bath by consecutive thermal treatments under reduced pressure. Accordingly, the recovered ILs were utilized to dissolve 13 wt.% cellulose in each cycle, without the addition of make-up IL, to form a homogeneous solution suitable for the dry-jet wet spinning. Using [mTBDH] [OAc], cellulose could be fully dissolved in all five cycles. In contrast, cellulose dissolution was only possible with fresh [DBNH][OAc] as the ability to dissolve cellulose was lost after the first recovery. This study focuses on the composition of the recovered ILs and the extent of side-products generation. Additionally, we present the rheological properties of the solutions as well as the macromolecular and mechanical properties of th e regenerated fibres. Also, the toxicity of both solvents was investigated using Vibrio fischeri bacteria. Finally, the spun fibres from al l [mTBDH][OAc] spinning trials were combined to produce a demonstration dress (Paju), designed and sewn by Marimekko Design House in Finland.

The tear fluid protects the corneal epithelium from drying out as well as from invasion by pathogens. It also provides cell nutrients. Similarly to lung surfactant, it is composed of an aqueous phase covered by a lipid layer. Here we describe the molecular organization of the anterior lipid layer of the tear film. Artificial tear fluid lipid layers (ATFLLs) composed of egg yolk phosphatidylcholine (60 mol %), free fatty acids (20 mol %), cholesteryl oleate (10 mol %), and triglycerides (10 mol %) were deposited on the air-water interface and their physico-chemical behavior was compared to egg-yolk phosphatidylcholine monolayers by using Langmuir-film balance techniques, x-ray diffraction, and imaging techniques as well as in silico molecular level simulations. At low surface pressures, ATFLLs were organized at the air-water interface as heterogeneous monomolecular films. Upon compression the ATFLLs collapsed toward the air phase and formed hemispherelike lipid aggregates. This transition was reversible upon relaxation. These results were confirmed by molecular-level simulations of ATFLL, which further provided molecular-scale insight into the molecular distributions inside and dynamics of the tear film. Similar type of behavior is observed in lung surfactant but the folding takes place toward the aqueous phase. The results provide novel information of the function of lipids in the tear fluid.