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Ionic liquids (ILs) have been gaining widespread attention due to their plethora of applications. In particular, increasing studies are being carried out to enhance the biological applications of ILs. In this work, a newly synthesized peptide amphiphile comprised of tert-butyl (6-amino-1-((6-aminohexyl) amino)-1-oxohexan-2-yl) carbamate (TAOC) was conjugated with the peptide segment derived from laminin, YIGSR, and self-assembled to form nanofibers. The formed nanofibers were then blended with two separate ionic liquids, betainium bis(trifluoromethylsulfonyl)imide [Hbet][NTf2] and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C4mim][NTf2] to form nanohybrids. To the nanohybrids, collagen (Type IV) was incorporated to further enhance biocompatibility. Our results indicated that the imidazolium-based nanohybrids formed globular assemblies and displayed higher thermal stability and mechanical strength compared to [Hbet][NTf2]-based nanocomposites. The binding interactions with the ionic liquids were probed by FTIR spectroscopy, DSC, TGA as well as predictive COSMO-RS studies, which indicated the key role of hydrogen bonding and hydrophobic interactions. Cell studies with neural cortical cells revealed that in both cases, the nanohybrids reduced cytotoxicity compared to the neat ionic liquids. Furthermore, axonal growths were observed. Such ionic liquid infused peptide nanohybrids, particularly the imidazolium-based nanohybrid gels may have potential for biological applications.

Over the years, ionic liquids (ILs) have gained tremendous importance because of their unique properties and plethora of applications. In this work, we have developed a new nanoscale hybrid gel consisting of 1-ethyl-3-methylimidazolium dimethyl phosphate, [C2mim][dmp], and self-assembled peptide nanoassemblies. The peptide nanoassemblies were formed by self-assembly of a newly synthesized peptide bolaamphiphile bis(N-α-amido-threonine) 1,7 heptane dicarboxylate (ThrC7). Upon mild heating and sonication of the IL and ThrC7 nanoassemblies, ThrC7-IL nanocomposites were formed. We explored the formation of nanohybrids by varying the ratio of IL to ThrC7 assemblies. While at lower IL ratios, a gelatinous matrix was formed, at higher IL ratios, highly ordered multilayered structures were observed by atomic force microscopy (AFM) imaging. The interactions between the ThrC7 nanofibers and [C2mim][dmp] IL were probed by Fourier transform infrared spectroscopy, transmission electron microscopy, and AFM imaging. Differential scanning calorimetry and thermogravimetric analysis showed that the nanohybrids illustrated distinct thermal phase changes due to changes in hydrogen bonding interactions and unfolding of the nanoassemblies. The viscoelastic behavior of the nanohybrids indicated that the materials displayed higher storage modulus upon incorporation of the ThrC7 nanoassemblies when compared to the IL. Furthermore, the nanohybrids were found to adhere to and promote proliferation of human dermal fibroblasts, while cytotoxicity was observed toward MCF-7 breast cancer cells. Thus, for the first time, we have developed peptide-based nanohybrids with an imidazolium-based IL with unique structural properties that may open new avenues for exploring potential biological applications.

The photochemistry of the charge transfer (CT) band of the room temperature ionic liquid (RTIL) 1-hexyl-3-methylimidazolium bromide (HMIm + /Br − ) is investigated using near-IR to vis ultrafast transient absorption (TA) and steady-state UV absorption spectroscopies. Continuous irradiation of the CT band at 266 nm results in the formation of photo-products that absorb strongly at 266 nm. It is shown that these photo-products, which are apparently very stable, adversely affect ultrafast TA measurements. Elimination of these effects reveals at least two transient species that exist within the TA detection window of 100 fs to 3 ns and 500–1250 nm. One of the components is a short-lived (

We report the synthesis, characterization and cellulose dissolution properties of a series of ionic liquids bearing alkyl and hydroxyl-functionalized imidazolium and pyrrolidinium cations, and dial...

Ionic liquids are organic salts that have melting points below 100 °C and they may serve as environmentally friendlier alternatives to the toxic and/or corrosive chemicals usually used to p...

A few classes of ionic liquids were synthesized and investigated for their physical properties as a function of structural variation. Bis(oxalato)borate (BOB) and bis(trifluoromethylsulfonyl)imide (NTf2) ionic liquids (ILs) containing pyridinium, 4-dimethylaminopyridinium (DMAP) and pyrrolidinium cations bearing alkyl, benzyl, hydroxyalkyl and alkoxy substituents, were prepared from the corresponding halide salts. The physical properties of the DMAP based ionic liquids including viscosity, conductivity and thermal profiles were compared to those of their unsubstituted pyridinium analogues. The properties of the BOB and NTf2 salts bearing similar cations were also compared. It was found that the DMAP salts were easier to synthesize and purify and have higher thermal decomposition points compared to their pyridinium and pyrrolidinium analogues. The BOB salts were found to be higher melting and more viscous than the NTf2 salts. The synthesis and physical properties of the various ILs will be discussed.

Previously unreported bis(oxalato)borate (BOB) ionic liquids (ILs) containing imidazolium, pyridinium, and pyrrolidinium cations were prepared from the corresponding halide salts by reaction with sodium bis(oxalato)borate (NaBOB), and their properties are reported. Pulse radiolysis experiments revealed that the BOB anion scavenges solvated electrons with rate constants of ∼3×10 8 M −1 s −1 in the ionic liquid C 4 mpyrr NTf 2 and 2.8×10 7 M −1 s −1 in water. This reactivity indicates that BOB ILs may be too sensitive to be used as neat solvents for nuclear separations processes in high radiation fields but may still be useful for preventing criticality while processing relatively “cold” fissile actinides.

Herein is reported the preparation of several series of symmetrical polyammonium salts that serve as cationic lipids or precursors thereof, and are structurally based on several series of parent diamines where dimethylazonia functionalities are present, separated by a central structural unit, and pendant terminal chains. The resultant materials are of significant interest for a variety of purposes, such as serving as antihydrophobic species and as transfectins, the details of which are provided in separate reports. Attempts to effect selective alkylation to provide the corresponding unsymmetrical cationic lipids were without success, always leading to relatively useless mixtures of products.

A series of stereoisomeric ammonium salts containing the 1,2-dihydroxypropyl unit were prepared. Of particular interest to us are those salts that were found to be ionic liquids, although some are solids at room temperature. The thermochemical properties of these new materials are reported.

Preparations are reported for an extensive series of phosphate salts of polyammonium species from the corresponding halide salts. The phosphate salts, as anhydrous materials, are liquid at or near room temperature. Three approaches for the preparation of these materials are noted, including treatment with aqueous hexafluorophosphoric acid, classical ion exchange methods, and treatment with 85% phosphoric acid. The last of these provides the most desirable results. Several monocationic phosphate salts have also been prepared for comparison with other types of ionic liquids.

The activity of four metagenomic enzymes and an enzyme cloned from the straw mushroom, Volvariella volvacea were studied in the following ionic liquids, 1,3-dimethylimidazolium dimethyl phosphate, [mmim][dmp], 1-ethyl-3-methylimidazolium dimethyl phosphate, [emim][dmp], 1-ethyl-3-methylimidazolium diethyl phosphate, [emim][dep] and 1-ethyl-3-methylimidazolium acetate, [emim][OAc]. Activity was determined by analyzing the hydrolysis of para-nitrobenzene carbohydrate derivatives. In general, the enzymes were most active in the dimethyl phosphate ionic liquids, followed by acetate. Generally speaking, activity decreased sharply for concentrations of [emim][dep] above 10% v/v, while the other ionic liquids showed less impact on activity up to 20% v/v.

A new solid-phase microextraction (SPME) procedure using an ionic liquid (IL) has been developed. Reusable IL-based SPME fiber was prepared for the first time by fixing IL through cross-linkage of IL impregnated silicone elastomer on the surface of a fused silica fiber. 1-Ethoxyethyl-3-methylimidazloium bis(trifluoromethane) sulfonylimide ([EeMim][NTf(2)]) ionic liquid was employed as a demonstration and the prepared fiber was applied to the forensic headspace determination of methamphetamine (MAP) and amphetamine (AP) in human urine samples. Important extraction parameters including the concentration of salt and base in sample matrix, extraction temperature and extraction time were investigated and optimized. Combined with gas chromatography/mass spectrometry (GC/MS) working in selected ion monitoring (SIM) mode, the new method showed good linearity in the range of 20-1500 microg L(-1), good repeatability (RSD7.5% for MAP, and11.5% for AP, n=6), and low detection limits (0.1 microg L(-1) for MAP and 0.5 microg L(-1) for AP). Feasibility of the method was evaluated by analyzing human urine samples. Although IL-based SPME is still at the beginning of its development stage, the results obtained by this work showed that it is a promising simple, fast and sensitive sample preparation method.

In our continuing investigation of polycationic salts for purposes of antimicrobial action, ion-channel blocking, and construction of ionic liquids, we have prepared several series of polycationic salts derived from carbohydrate precursors. These salts are currently being investigated for optimal efficacy as antibacterials and antifungals, as well as for other applications. The syntheses of such series of salts are described here along with preliminary antibacterial testing results and a discussion of their properties indicating their potential utility for several purposes.

Herein is reported the preparation of several series of polyammonium salts that serve as cationic lipids or precursors thereof, and are structurally based on the parent diamine 1,4-diazabicyclo[2.2.2]octane (dabco). Through selective alkylation of dabco a variety of di- and tetracationic lipid species and precursors thereof have been prepared. The resultant materials are of significant interest for a variety of purposes, including serving as antimicrobial agents and antihydrophobic species, the details of which are provided in separate reports.