Do Ionic Liquids Exhibit the Required Characteristics to Dissolve, Extract, Stabilize, and Purify Proteins? Past-Present-Future Assessment.

Proteins are highly labile molecules, thus requiring the presence of appropriate solvents and excipients in their liquid milieu to keep their stability and biological activity. In this field, ionic liquids (ILs) have gained momentum in the past years, with a relevant number of works reporting their successful use to dissolve, stabilize, extract, and purify proteins. Different approaches in protein-IL systems have been reported, namely, proteins dissolved in (i) neat ILs, (ii) ILs as co-solvents, (iii) ILs as adjuvants, (iv) ILs as surfactants, (v) ILs as phase-forming components of aqueous biphasic systems, and (vi) IL-polymer-protein/peptide conjugates. Herein, we critically analyze the works published to date and provide a comprehensive understanding of the IL-protein interactions affecting the stability, conformational alteration, unfolding, misfolding, and refolding of proteins while providing directions for future studies in view of imminent applications. Overall, it has been found that the stability or purification of proteins by ILs is bispecific and depends on the structure of both the IL and the protein. The most promising IL-protein systems are identified, which is valuable when foreseeing market applications of ILs, e.g., in "protein packaging" and "detergent applications". Future directions and other possibilities of IL-protein systems in light-harvesting and biotechnology/biomedical applications are discussed.

Mixed Aggregates of Surface-Active Ionic Liquids and 14-2-14 Gemini Surfactants in an Aqueous Medium as Fluid Scaffolds for Enzymology of Cytochrome-c.

The aggregation behavior of the surface-active ionic liquid (SAIL), 3-(2-(hexadecyloxy)-2-oxoethyl)-1-methyl-1H-imidazol-3-ium chloride, [C16Emim][Cl], and a gemini surfactant (GS) (14-2-14) in the whole mole fraction range has been investigated in an aqueous medium employing various techniques. Experimentally obtained values of critical aggregation concentration (cac) are in good agreement with the theoretical cac values obtained using Clint's equation. Rubingh's model has been employed to evaluate the extent of synergistic interactions between two components, which has been found to be dependent upon the composition of a mixture of surfactants. The polarity index, hydrodynamic diameter (Dh), zeta potential (ζ-Pot.), and morphology of the aggregates have been found to be dependent upon the extent of hydrophobic as well as dipolar interactions and the degree of counterion binding governed by the content of the GS in mixed aggregates. Thermodynamic parameters evaluated employing isothermal titration calorimetry have revealed the aggregation as an entropy-driven process. Density functional theory calculations provide a detailed account of the SAIL-GS interactions at the molecular level. The reduced density gradient (RDG) along with the calculated isosurfaces asserts that the dominant interactions are noncovalent interactions. Furthermore, the enzymology of cytochrome-c in the aqueous SAIL-GS aggregated systems has been investigated and a two-fold increase in the enzyme activity has been observed in the aggregates formed by the GS as compared to that in buffer.

Water Induced Alterations in Self-Assembly of a Bio-Surfactant in Deep Eutectic Solvent for Enhanced Enzyme Activity.

Deep eutectic solvents (DESs) meet important requirements for green solvent technology, including non-toxicity, biodegradability, sustainability, and affordability. Despite possessing low cohesive energy density than water, DESs have been found to support the self-assembly of amphiphiles. It is very much pertinent to examine the effect of water on self-assembly of surfactants in DESs as the presence of water alters the inherent structure of DES, which is expected to affect the characteristic properties of self-assembly. Following this, we have investigated the self-assembly of amino-acid based surfactant, Sodium N-lauroyl sarcosinate (SLS), in DES-water mixtures (10, 30 and 50 w/w% of water) and explored the catalytic activity of Cytochrome-c (Cyt-c) in the formed colloidal systems. Investigations using surface tension, fluorescence, dynamic light scattering (DLS), and isothermal titration calorimetry (ITC) have shown that DES-water mixtures promote the aggregation of SLS, resulting in the lower critical aggregation concentration (cac ∼1.5-6-fold) of the surfactant as compared to water. The nanoclustering of DES at low water content and it's complete de-structuring at high water content affects the self-assembly in a contrasting manner governed by different set of interactions. Further, Cyt-c dispersed in DES-water colloidal solutions demonstrated 5-fold higher peroxidase activity than that observed in phosphate buffer.

Water-pluronic-ionic liquid based microemulsions: Preparation, characterization and application as micro-reactor for enhanced catalytic activity of Cytochrome-c.

Microemulsions (µEs), comprising water as polar component, pluronic (normal, L35 and reverse, 10R5) as surfactant and a hydrophobic ionic liquid (HIL) as non-polar component have been prepared and characterized. Owing to higher surface activity, pluronics have promoted the formation of µEs without the use of co-surfactant. Thus prepared µEs have been utilized as nano-reactors for the oxidation of guaiacol in the presence of Cytochrome-c (Cyt-c) at 15, 20, and 25 °C. A 3.2- and 1.3-fold increase in the rate of formation of product of enzymatic catalysis in direct µE (HIL-in-water) with reverse pluronic (10R5) is observed at 15 and 20 °C as compared to that in buffer. However, negligible enzymatic activity is observed in the direct µE formed by normal pluronic (L35). The catalytic activity of Cyt-c decreases in reverse µEs (water-in-HIL) as compared to direct µEs irrespective of the nature of pluronic used. The contrasting nature of nano-interfaces formed by pluronics in µEs and the extent of hydration of these nano-interfaces controlled by temperature exerts varying influence on the catalytic activity of Cyt-c. It is expected that the present work would result in providing a versatile platform for the creation of new IL and pluronic-based µEs for bio-catalytic applications, which have never been reported.

Spontaneous Fibrillation of Bovine Serum Albumin at Physiological Temperatures Promoted by Hydrolysis-Prone Ionic Liquids.

This study highlights the role of time-dependent hydrolysis of ionic liquid anion, [BF4]-, of ionic liquid (IL), 1-ethyl-3-methylimidazolium tetrafluoroborate, [C2mim][BF4], which results in ever-changing pH conditions. Such pH changes along with the ionic interactions bring conformational changes in bovine serum albumin (BSA), leading to the formation of amyloid fibers at 37 °C without external control of pH or addition of electrolyte. The fibrillation of BSA occurs spontaneously with the addition of IL; however, the highest growth rate has been observed in aqueous solution of 10% IL (v/v %) among investigated systems. Thioflavin T (ThT) fluorescence emission has been employed to monitor the growth and development of ß-sheet content in amyloid fibrils. The structural alterations in BSA have also been investigated using intrinsic fluorescence measurements. Circular dichroism (CD) measurements confirmed the formation of amyloid fibrils. Transmission electron microscopy (TEM) has been explored to establish the morphologies of BSA fibrils at different intervals of time, whereas atomic force microscopy (AFM) has established the helically twisted nature of grown amyloid fibrils. The docking studies have been utilized to understand the insertion of IL ions in different domains of BSA, which along with decreased pH cause the unfolding and growth of BSA into amyloid fibrils. It is expected that the results obtained from this study would help to understand the impact of IL containing [BF4]- anion on protein stability and aggregation along with providing a new platform to control the formation of amyloid fibrils and other biomaterials driven via ionic interactions and alterations in pH.

Polymeric Precipitation Inhibitor Based Supersaturable Self-microemulsifying Drug Delivery System of Canagliflozin: Optimization and Evaluation.

BACKGROUND: The present investigation attempts to optimize Supersaturable lipid based formulation (SS SMEDDS) of Biopharmaceutical Classification System (BCS) class IV drug canagliflozin (CFZ) and evaluating the oral bioavailability of the formulation. METHODS: Preliminary screening revealed Poloxamer 188 to most effectively inhibit precipitation of CFZ after dispersion during in vitro supersaturation studies. Box Behnken Design was employed for designing different formulations, and various statistical analyses were done to select an appropriate mathematical model. The optimized formulation (OSS 1) was evaluated for in vitro drug release and ex vivo permeation studies to evaluate drug release and permeation rate. Pharmacokinetic studies have been carried out according to standard methodologies. RESULTS: The optimized formulation (OSS 1) containing 781.1 mg SS SMEDDS and 2.24% w/w Poloxamer 188 was developed at a temperature of 60°C, which revealed nano-globule size with negligible aggregation. Isothermal titration calorimetry revealed the thermodynamic state of formed microemulsion with negative ΔG. The optimized formulation was observed to possess physical stability under different stress conditions and acceptable drug content. In vitro dissolution of optimized SS SMEDDS revealed a higher dissolution rate of CFZ as compared to native forms of CFZ. The permeability of CFZ from optimized SS SMEDDS across various excised segments of rat intestine was observed to be multifold higher as manifested by 2.05-fold higher Cmax and 5.64- fold higher AUC0-36h following oral administration to Wistar rats. CONCLUSION: The results could be attributed to substantial lymphatic uptake and P-glycoprotein substrate affinity of CFZ in SS SMEDDS investigated through chylomicron and P-glycoprotein inhibition approach, respectively.

Biamphiphilic ionic liquid based aqueous microemulsions as an efficient catalytic medium for cytochrome c.

Considering the remarkable applicability of ionic liquids (ILs) in bio-catalysis involving enzymes, herein, we report new IL based aqueous microemulsions as a catalytic reactor for cytochrome c (Cyt-c). Microemulsions (µEs), comprising water as the polar component, imidazolium (cation) and dioctylsulfosuccinate (AOT) (anion) based biamphiphilic ionic liquid (BAIL) as the surfactant and a hydrophobic ionic liquid (HIL) as the non-polar component have been prepared and characterized. The use of BAIL has promoted the formation of µEs without any co-surfactant, owing to its higher surface activity. The effect of ester- or amide-functionalization of the alkyl chain of the imidazolium cation of BAILs on the phase behavior of µEs has been investigated. The prepared µEs have been characterized via conductivity, dynamic light scattering (DLS), UV-vis absorption and steady-state fluorescence (using external polarity probes) techniques. The prepared µEs have been employed as nano-reactors for exploring the catalytic activity of Cyt-c. The formed BAIL-water nano-interfaces in reverse µEs have exerted a positive effect on the catalytic activity of Cyt-c stored in a water pool of reverse µEs. A five-fold higher rate constant in µEs as compared to buffer establishes µEs as a better catalytic medium. Furthermore, the differing nature of nano-interfaces created by BAILs and water in reverse µEs, depending on the functionalization of the alkyl chain of the cationic part of BAIL, has exerted varying influence on the catalytic activity of Cyt-c. It is expected that the present work will result in providing a versatile platform for the creation of new IL and water based µEs for bio-catalytic applications.

Antimicrobial Colloidal Complexes of Lysozyme with Bio-Based Surface Active Ionic Liquids in Aqueous Medium.

Bio-based surface-active ionic liquids (SAILs) have been synthesized and investigated for their complexation with lysozyme (LYZ) in an aqueous medium to develop antimicrobial SAIL-LYZ colloidal complexes. The synthesized SAILs, [Cho][Sar] and [Cho][Doc], are comprised of choline ([Cho]+) and lauryl sarcosinate ([Sar]-) or deoxycholate ([Doc]-). The constituent anions of the investigated SAILs are structurally dissimilar and thus resulted in contrasting complexation behavior toward LYZ, as suggested by the results obtained from different techniques. The interfacial behavior is monitored using tensiometry. Zeta-potential, turbidity, and dynamic light scattering results provide insights into the complexation phenomenon in bulk. The observations made from fluorescence and circular dichroism (CD) spectroscopy give information about the alterations in the inherent structure of LYZ. The thermodynamics of the binding of SAILs with LYZ is monitored using isothermal titration calorimetry (ITC). Computer simulations have been utilized to determine the preferential binding site of SAILs on LYZ, which supports the results obtained from different techniques. Interestingly, LYZ complexed with the investigated SAILs, which are non-antimicrobial, is found to exhibit enhanced antimicrobial activity depending upon the concentration regime of the used SAIL. In this way, we have developed new antimicrobial colloidal complexes of SAILs and LYZ. The present study provides useful insights to synthesize new bio-based SAILs to be utilized for creating colloidal formulations applicable in enzyme/protein stabilization, storage, and other biomedical applications.

Aqueous colloidal systems of bovine serum albumin and functionalized surface active ionic liquids for material transport.

Detailed physicochemical and computational investigation are made to explore different aspects of complexation between bovine serum albumin (BSA) and three structurally different surface active ionic liquids (SAILs), 1-dodecyl-3-methylimidazolium chloride, [C12mim][Cl]; 3-(2-(dodecylamino)-2-oxoethyl)-1-methyl-1H-imidazol-3-ium chloride, [C12Amim][Cl] and 3-methyl-1-dodecyloxy carbonyl methylimidazolium chloride, [C12Emim][Cl]. The interfacial and bulk complexation behavior has been monitored using tensiometry, conductivity, steady-state fluorescence and turbidity measurements. Thermodynamic insights about complexation have been obtained using isothermal titration calorimetry (ITC) measurements whereas molecular docking studies were used to predict the possible binding sites of SAILs on BSA. The information obtained from these studies helped in establishing the formed BSA-SAIL complex as a pH dependent colloidal transport system for controlled transport of a lipophilic dye, Rhodamine 6G (R6G), in aqueous phase, which is supported by confocal laser scanning microscopy (CLSM). In the present work, the effect of functionalization over the alkyl chain of SAILs, modulating the colloidal properties of SAIL-BSA systems, has been explored along with the utilization of these complexes as a pH dependent reversible carrier of lipophilic molecules. It is expected that besides providing basic understanding of colloidal complexes of BSA with SAILs, the present work is expected to be helpful in extending the applications of such colloidal systems for material transport.

One-pot sustainable preparation of sunlight active ZnS@graphene nano-composites using a Zn containing surface active ionic liquid.

Herein we report a facile and sustainable method for the preparation of ZnS@graphene nano-composites (NCs). An appreciable amount of graphene is obtained by liquid-phase exfoliation using a zinc-containing surface active ionic liquid (SAIL). It is followed by in situ preparation of ZnS quantum dot (QD) decorated graphene sheets at room temperature for the first time. The employed method is distinct from all previous reports, as we have employed graphene instead of graphene oxide (GO) or reduced graphene oxide (rGO) and used relatively fewer chemicals. Further, a SAIL is employed as a precursor of Zn2+ as well as a template for the preparation of ZnS QDs onto graphene. The prepared ZnS@graphene NCs show enhanced photocatalytic performance for the degradation of Rhodamine B dye under sunlight and ciprofloxacin antibiotic under visible light as compared to bare ZnS QDs. The better photocatalytic activity of the NCs under visible light compared to that reported in the literature along with the ease of preparation is advantageous for scaling-up the process.

Aqueous systems of a surface active ionic liquid having an aromatic anion: phase behavior, exfoliation of graphene flakes and its hydrogelation.

Surface active ionic liquid (SAIL) induced hydrogelation, in the absence of additives, is important considering the properties of soft-hydrogels that can be utilized in different applications. The present study is concerned with the phase behavior and hydrogelation of a SAIL, 1-hexadecyl-3-methylimidazolium p-toluenesulfonate, [C16mim][PTS]. The obtained information about the phase behavior along with the surfactant like behavior of the SAIL was exploited for effective exfoliation of graphene-flakes from graphite in aqueous medium that remain stable for at least one month. Thus the obtained dispersion of graphene-flakes was subsequently hydrogelated exploiting the observations made from the phase behavior of the SAIL, via entanglement of long worm-like micelles of the SAIL formed at higher concentration. The obtained graphene-flake based hydrogels were found to be equally stable as compared to the blank hydrogel as well as against centrifugation. The low melting point of hydrogel facilitates the extraction of graphene-flakes from the hydrogel matrix by heating and diluting the gel and there is no sign of agglomeration in the extracted graphene-flakes even if the extraction is carried out after a period of three months. The present work is an exemplary study on exfoliation, hydrogelation and extraction of graphene-flakes from a hydrogel, when required, using a SAIL and is expected to provide a new platform for utilization of SAILs for efficient graphene exfoliation and subsequent preparation of functional materials.

Effect of the Alkyl Chain Length of Amphiphilic Ionic Liquids on the Structure and Dynamics of Model Lipid Membranes.

We compare the biophysical and structural aspects of the interaction of amphiphilic ionic liquids containing 1-alkyl-3-methylimidazolium cation ([CnMIM]+, n = 8, 12, or 16) with membranes composed of zwitterionic 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) or anionic 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-rac-glycerol (POPG). Liposome affinity and permeabilization were determined using ζ-potential and fluorescence studies, correlated with the cytoxicity of [CnMIM]+Br- toward HeLa cell lines. Membrane affinity is strongest in the case of [C16MIM]+Br- followed by [C12MIM]+Br- and [C8MIM]+Br- for both membranes, and trends remained the same in the case of membrane permeability and cytotoxicity. Solid-state NMR spectroscopy was used to localize [CnMIM]+ inside the lipid bilayers and to study their impact on the head group and acyl chain structures and dynamics of the lipid molecules. The charged ring moiety of the [CnMIM]+ is localized in the lipid-water interface of the membranes irrespective of the chain length and membrane surface charge. While [C8MIM]+ binds the membrane most weakly, it induces the largest disorder in the lipid chain region. A lack of fast flip-flop motions of the amphiphiles in the case of long chain [C16MIM]+ is suggested to render the membrane unstable, which increases its permeability. Between the lipid molecules, the POPC membrane incurs larger disorder in lipid chain packing upon insertion of [CnMIM]+ molecules. The study provides structural details of the impact of increasing chain lengths in [CnMIM]+ on the structural properties of lipid bilayers.

Liquid crystalline microspheres of azobenzene amphiphiles formed by thermally induced pH changes in binary water-hydrolytic ionic liquid media.

Anionic azobenzene-containing bilayered membranes dispersed in binary water-ionic liquid (IL) media undergo proton-responsive transformation into liquid crystalline microspheres (LCMs). This transformation was induced by protons released by the heat-induced hydrolysis of tetrafluoroborate ions in the ILs. This work demonstrates the first beneficial use of hydrolysis-susceptible ILs in chemistry.

Complexation Behavior of ß-Lactoglobulin with Surface Active Ionic Liquids in Aqueous Solutions: An Experimental and Computational Approach.

The nature of functionalization of alkyl chains of imidazolium-based surface active ionic liquids (SAILs) with amide or ester moiety led to contrasting complexation behavior toward the globular protein, bovine serum albumin. This prompted us to further investigate the SAIL-dependent colloidal behavior of another globular protein, ß-lactoglobulin (ßLG), to probe the origin of varying structural transformations in globular proteins induced by SAILs. Herein, we investigated the colloidal systems of ßLG, rich in ß-sheet structure, in the presence of four structurally different SAILs using a multitechnique approach. The complexation behavior, both at the air-solution interface and in bulk, is supplemented by different techniques. Docking studies have complemented the obtained experimental results. The specificity of structure, H-bonding ability of SAILs, and inherent structure of protein are found to govern their complexation behavior in terms of size, shape, and polarity of protein-SAIL complexes along with varying degrees of structural alterations in globular proteins. The present work is expected to be very useful in establishing a deep understanding of the structure-property relationship between the nature of proteins and SAILs for their complexation and colloidal behavior for various biomedical applications.

Thermally Stable Ionic Liquid-Based Microemulsions for High-Temperature Stabilization of Lysozyme at Nanointerfaces.

The development of new strategies for thermal stability and storage of enzymes is very important, considering the nonretention of catalytic activity by enzymes under harsh conditions of temperature. Following this, herein, a new approach based on the interfacial adsorption of lysozyme (LYZ) at nanointerfaces of ionic liquid (IL)-based microemulsions, for enhanced thermal stability of LYZ, is reported. Microemulsions (MEs) composed of dialkyl imidazolium-based surface active ILs (SAILs) as surfactants, ILs as the nonpolar phase, and ethylene glycol (EG) as the polar phase, without any cosurfactants, have been prepared and characterized in detail. Various regions corresponding to polar-in-IL, bicontinuous, and IL-in-polar phases have been characterized using conductivity measurements. Dynamic light scattering (DLS) measurements have provided insights into the size distribution of microdroplets, whereas temperature-dependent DLS measurements established the thermal stability of the MEs. Nanointerfaces formed by SAILs with EG in thermally stable reverse MEs act as fluid scaffolds to adsorb and provide thermal stability, up to 120 °C, to LYZ. Thermally treated LYZ upon extraction into a buffer shows enzyme activity owing to negligible change in the active site of LYZ, as marked by retention of microenvironment of Trp residues present in the active site of LYZ. The present work is expected to establish a new platform for the development of novel nanointerfaces utilizing biobased components for other biomedical applications.

Inner membrane complex 1l protein of Plasmodium falciparum links membrane lipids with cytoskeletal element 'actin' and its associated motor 'myosin'.

The inner membrane complex (IMC) is a defining feature of apicomplexans comprising of lipid and protein components involved in gliding motility and host cell invasion. Motility of Plasmodium parasites is accomplished by an actin and myosin based glideosome machinery situated between the parasite plasma membrane (PPM) and IMC. Here, we have studied in vivo expression and localization of a Plasmodium falciparum (Pf) IMC protein 'PfIMC1l' and characterized it functionally by using biochemical assays. We have identified cytoskeletal protein 'actin' and motor protein 'myosin' as novel binding partners of PfIMC1l, alongside its interaction with the lipids 'cholesterol' and 'phosphatidyl-inositol 4, 5 bisphosphate' (PIP2). While actin and myosin compete for interaction with PfIMC1l, actin and either of the lipids (cholesterol or PIP2) simultaneously bind PfIMC1l. Interestingly, PfIMC1l showed enhanced binding with actin in the presence of calcium ions, and displayed direct binding with calcium. Based on our in silico analysis and experimental data showing PfIMC1l-actin/myosin and PfIMC1l-lipid interactions, we propose that this protein may anchor the IMC membrane with the parasite gliding apparatus. Considering its binding with key proteins involved in motility viz. myosin and actin (with calcium dependence), we suggest that PfIMC1l may have a role in the locomotion of Plasmodium.

Sustainable preparation of sunlight active α-Fe2O3 nanoparticles using iron containing ionic liquids for photocatalytic applications.

Inspired by the nano-segregation of ionic liquids (ILs) into bi-continuous structures constituting of arrays of ionic and non-ionic components, herein, a new and sustainable strategy for preparation of mesh-like nano-sheet α-Fe2O3 nanoparticles and their photo-catalytic activity under sunlight, is presented. For the purpose, metal (iron) containing ionic liquids (MILs), 1-alkyl-3-methylimidazolium tetrachloroferrates, [C n mim][FeCl4], (n = 4, 8 and 16), which not only act as precursors and solvents but also as structure directing agents have been used. Thus prepared NPs show MIL dependent structural, photophysical and magnetic properties. The catalytic efficiency of NPs has been tested for the photo-degradation of organic dyes (Rhodamine B) in aqueous solution under sunlight. The NPs are found to exhibit comparable catalytic efficiency under sunlight as compared to that observed under high intensity visible lamplight, without showing a decline in their catalytic efficiency even after 4 catalytic cycles. It is anticipated that the present work will provide a new platform for preparation of sunlight active nanomaterials for photo-catalytic applications with control over the structural and physical properties via varying the molecular structure of MILs.

Hydrophobically Driven Morphologically Diverse Self-Assembled Architectures of Deoxycholate and Imidazolium-Based Biamphiphilic Ionic Liquids in Aqueous Medium.

Biamphiphilic ionic liquids (BAILs) having amphiphilic cation and anion are thought to exhibit improved surface activity and colloidal stability to be utilized in different applications. For their effective use, a control over synergetic hydrophobic and electrostatic interactions between oppositely charged ions along with the possibility of tuning of hydrophobicity of the core of aggregates is required. Focusing on this, new BAILs comprising a bile salt anion, deoxycholate, [DC]-, and 1-alkyl-3-methylimidazolium cations, [C nmim]+ ( n = 2, 4, 6, 8, and 12), were synthesized and characterized for their behavior at air-solution interface as well as in bulk. The synthesized BAILs exhibit high surface activity and self-assemble in the form of different architectures ranging from nanosheets (NSs), nanorods, and vesicles with varying hydrophobicities of the formed core of aggregates, depending on the length of alkyl chain of [C nmim]+. Analysis of various parameters obtained from investigated techniques suggested the changing role of [C nmim]+ from a counterion ( n = 2 and 4) to a cosurfactant ( n = 8 and 12) via a borderline case of [C6mim]+. This changeover in the nature of counterion controlled by hydrophobicity of alkyl chain resulted in morphological diversification in self-assembled architectures via varying set of interactions. It is believed that the present work would offer new perspectives in the self-assembly phenomenon of surfactants in general and surface active ionic liquids in particular to devise new strategies for inducing morphology-dependent functionality in self-assembled structures of BAILs.

Colloidal systems of surface active ionic liquids and sodium carboxymethyl cellulose: physicochemical investigations and preparation of magnetic nano-composites.

The complexation of three surface active ionic liquids (SAILs): 1-methyl-3-dodecylimidazolium chloride, [C12mim][Cl], and its amide, 3-(2-(dodecylamino)-2-oxoethyl)-1-methyl-1H-imidazol-3-ium chloride, [C12Amim][Cl], and ester, 3-methyl-1-dodecyloxycarbonylmethylimidazolium chloride, [C12Emim][Cl], functionalized counterparts with sodium carboxymethylcellulose (NaCMC), has been investigated. The behaviour of colloidal systems comprising SAILs and NaCMC at the air-solution interface has been investigated using tensiometry. The formed colloids in the bulk have been characterized for their mobility, surface charge, shape, size and morphology along with their relative hydrophobicity/hydrophilicity and other thermodynamic parameters of interest in different concentration regimes of the SAILs. For this, various techniques such as conductivity, turbidity, dynamic light scattering, ζ-potential, scanning electron microscopy (SEM) and fluorescence measurements have been employed. H-bonding prone SAILs, i.e. [C12Amim][Cl] and [C12Emim][Cl], are found to interact with NaCMC in a contrasting manner as compared to their non-functionalized counterpart. The formed complexes of SAILs and NaCMC have been explored for the one pot preparation of magnetic nano-composites by doping colloids of SAILs and NaCMC with zinc ferrite (ZnFe3O4) nano-particles. The prepared magnetic nano-composites are characterised using X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). It is expected that the present work would offer a new colloidal route for the preparation of SAILs and biopolymer assisted nano-composites along with providing physical insights into the complexation phenomenon.

Unprecedented self-assembled architectures of surface-active ionic liquids in aqueous medium.

The formation of ultra-thin 2D crystalline nano-sheets, -spindles and -ribbons by self-assembly of benzimidazolium-based single-tailed surface active ionic liquids (SAILs) is observed for the first time. The nature of formed bilayer architectures is governed by the functionalization of alkyl chains of SAILs via an amide or ester moiety.