Selective Partition of Lipopeptides from Fermentation Broth: A Green and Sustainable Approach.

Lipopeptide (LP) biosurfactants from microbes have the potential to gradually replace chemical synthetic surfactants and fit the contemporary green and sustainable industrial production concept. However, their active participation is comparatively low in the global market pertaining to their low yield in microbial broth and costly downstream processes arising due to tedious isolation and purification methods. Herein, an efficient extraction method is developed that utilizes an aqueous biphasic system (ABS) comprising ionic liquids and polypropylene glycol 400 (PPG) to selectively extract a mixture of cyclic lipopeptides, namely, surfactin and fengycin from the culture broth of Bacillus amyloliquefaciens 5NPA-1, isolated from the halophyte Salicornia brachiata Roxb. Out of four different ABSs, the ABS composed of 2-hydroxyethyl ammonium formate and PPG displayed a maximum extraction efficiency of 82.30%. PPG-rich phase containing lipopeptides exhibited excellent antimicrobial and mosquito larvicidal properties with no toxic effect on plants. The developed method is simple, novel and accelerates the application of cyclic lipopeptides produced by the microbial source.

Recent Developments on Ionic Liquids and Deep Eutectic Solvents for Drug Delivery Applications.

The field of Ionic liquids (ILs) and deep eutectic solvents (DESs) is continuously expanding due to their exceptional unique properties and highly tunable nature, which finds applications in broad areas of modern science. Considering numerous possible IL and DES combinations prepared with active pharmaceutical ingredients (APIs), they find applications in pharmaceutical sciences. They can also serve as potential components of drug formulations and hence they have drawn the attention of formulation scientists. Herein, the concept of pharmaceutical ILs and DESs are discussed briefly. The possible applications of these solvent systems for slow drug delivery including nanoscale drug delivery are discussed citing various examples from the published literature. Although the ILs and DESs are found to be suitable for various drug delivery applications but still none of the slow drug delivery vehicles based on these solvents is in practical use. The data relating to long-term toxicity upon administration in the human body followed by various safety evaluations, clinical trials, etc. are pending for such new drug delivery systems. However, proof of concept studies done on the retention of biological activities in the ionic form is quite encouraging and such studies indicate the possibility of application of such new systems in the development of biomedical research and related industries in near future.

Preparation of seaweed polysaccharide based hydrophobic composite membranes for the separation of oil/water emulsion and protein.

Agarose is a seaweed-based polysaccharide and is widely used for the separation of nucleic acids in molecular biology. Cross-linked agarose beads are also used as solid-phase matrices in size exclusion chromatography for the separation of proteins. To find the application of agarose for the separation of oil/water emulsion and protein, herein hydrophobic derivative of the seaweed biopolymer [MW (1.27 ± 0.17) × 10 5 g/mol; sulphate content (0.29 ± 0.09) %, gel strength (2242 ± 21) g/cm2] is prepared by reacting the biopolymer with stearic acid and was used to prepare a composite membrane on polyester fabric. The oil and BSA rejection performance of the composite membrane was greater than 98%. The rejection rate increased with the increase in polymer content in the respective membranes for both oil/water and protein separation. The composite membrane showed a stable oil/water emulsion and protein separation performance over a period of six hours. Due to the biodegradable nature of the major components of the membrane, it has the potential for industrial applications.

Optimization of the spontaneous adsorption of food colors from aqueous medium using functionalized Chitosan/Cinnamaldehyde hydrogel.

Hydrogels are considered as practical and proficient materials in adsorption and removal of soluble lethal molecules from aqueous system. They are also rapid-decomposable and economical materials besides their diverse preventive claims. In current study, Cinnamaldehyde (C), a natural defensive compound and Chitosan (Ch), natural occurring bio-macromolecule are considered to develop bio-inspired hydrogel (ChC). The structural and surface characteristics of ChC (13C solid state NMR, FT-IR, UV-Vis and SEM) are investigated to confirm the successful grafting. The origami of gelation in ChC performs an excellent adsorption activity towards food dyes, Carmoisine (CA) and Tartrazine (TA), which are contaminated by the accumulation during excess release from catering and chemical industries in aqueous system. The adsorption performance is thoroughly screened by varying the pH, ChC dosage, dye concentration, contact time and temperature in aqueous system. Thermodynamic and Kinetics study suggest the natural tendency of adsorption with a good reusability up to 3 cycles. The main mechanism for spontaneous adsorption is initiated by capturing of TA/CA in porous surface followed by the ionic interactions and formation of H-bondings. ChC based adsorption is an excellent and potential approach to control the toxicants for the water-pollution and water-preservation.

Seaweed Polysaccharide Based Products and Materials: An Assessment on Their Production from a Sustainability Point of View.

Among the various natural polymers, polysaccharides are one of the oldest biopolymers present on the Earth. They play a very crucial role in the survival of both animals and plants. Due to the presence of hydroxyl functional groups in most of the polysaccharides, it is easy to prepare their chemical derivatives. Several polysaccharide derivatives are widely used in a number of industrial applications. The polysaccharides such as cellulose, starch, chitosan, etc., have several applications but due to some distinguished characteristic properties, seaweed polysaccharides are preferred in a number of applications. This review covers published literature on the seaweed polysaccharides, their origin, and extraction from seaweeds, application, and chemical modification. Derivatization of the polysaccharides to impart new functionalities by chemical modification such as esterification, amidation, amination, C-N bond formation, sulphation, acetylation, phosphorylation, and graft copolymerization is discussed. The suitability of extraction of seaweed polysaccharides such as agar, carrageenan, and alginate using ionic solvent systems from a sustainability point of view and future prospects for efficient extraction and functionalization of seaweed polysaccharides is also included in this review article.

Synthesis, Colloidal Characterization and Targetability of Phenylboronic Acid Functionalized α-Tocopheryl Polyethylene Glycol Succinate in Cancer Cells.

This study reports targetable micelles developed after covalent functionalization of α-tocopheryl polyethylene glycol succinate (TPGS) with amino phenylboronic acid (APBA). Nuclear magnetic resonance (NMR) and infrared (IR) spectroscopic results showed successful attachment of APBA to the hydrophilic segment of TPGS. Dynamic light scattering and small-angle neutron scattering studies revealed that the conjugate self-assembled in water to produce spherical core-shell micelles (14-20 nm) which remained stable against temperature (ca. 25-45 °C) and pH changes. The micelles could solubilize a high payload of paclitaxel (PLX) without exhibiting changes in the average size. However, at the saturation solubility, drug molecules migrated from the core to the shell region and engaged with APBA groups via π-π stacking interaction. Confocal microscopy and cell sorting analyses verified the effective translocation ability of TPGS-APBA micelles in sialic acid (SA) expressing MDA-MB-453 cells. At equivalent PLX dose, TPGS-APBA micelles showed about a twofold improvement in apoptotic death among the cells exposed for 2 h. Our findings indicate that the attachment of APBA can be a potential strategy for improving the intra-cellular localization of carriers among cancer cells expressing SA residues.

Simultaneous morphological transformation of metal salt and conformations of DNA in a bio-based ionic liquid.

The extraordinary left handed conformation of DNA known as Z-DNA has attracted the attention of structural biologists due to its characteristic features such as its possible role in regulation of gene expression and genetic instability. There are number of physical parameters which can induce the conformational transformation of double helical B-DNA to Z-DNA. Among the various physical conditions, right-handed B-DNA can be transformed into left-handed Z-DNA in vitro at high salt concentrations or in vivo under physiological conditions. Herein DNA solubilized in a choline based ionic liquid namely choline formate was found to reduce Ag(I) salt into silver nanoparticles (AgNPs) with the size distribution of 10-20 nm. During the process, the interaction of DNA with the ionic liquid induces alteration in secondary structure of DNA (B-Z transition). The formation of the NPs was confirmed by UV-Vis spectrophotometer and Transmission Electron Microscopic (TEM) measurements, while the formation of Z-DNA was confirmed by circular dichroism (CD) spectroscopic measurements. Upon molecular docking studies, choline-formate was found to present different binding sites for its cation and anion and they promote torsions on DNA structure leading to possible changes in DNA three dimensional structures (B-Z transition).

High concentration solubility and stability of ɛ-poly-l-lysine in an ammonium-based ionic liquid: A suitable media for polypeptide packaging and biomaterial preparation.

Packaging of structurally sensitive biomolecules such as proteins, peptides and DNA in non-aqueous media at ambient conditions with chemical and structural stability is important to explore the potential of such biomacromolecules as substrate for functional biomaterial design and for biotechnological applications. In this perspective, solubility, chemical and structural stability of ɛ-poly-l-lysine (ɛ-PL), a homopolypeptide produced by Streptomyces albulus in different ionic liquids (ILs) namely 2-hydroxyethyl ammonium formate (2-HEAF), 2-hydroxyethyl ammonium acetate (2-HEAA), choline formate (Ch-Formate) and choline acetate (Ch-Acetate) was studied. Maximum solubility (15% w/v) of the homopolypeptide was observed in 2-HEAF and lowest was found in Ch-Formate (2% w/v). After regeneration of the dissolved polypeptide in the IL, the IL could be recycled and reused in the dissolution process. Unlike in other ILs, 3-15% w/v of ɛ-PL in 2-HEAF gave formation of a thixotropic thermoreversible soft gel. Molecular docking studies established favourable interactions of [2-HEA]+ cation over [Ch]+ with ɛ-PL indicating [2-HEA]+ as the most promising cation for the dissolution process. However, the role of the anions was also found to be important, which could lead to improvement in polypeptide solubility when combined to the selected cation. The findings demonstrate suitability of the ionic liquids for functionalization of polypeptides for biomaterial preparation.

Stimuli responsive ion gels based on polysaccharides and other polymers prepared using ionic liquids and deep eutectic solvents.

Ion gels and self-healing gels prepared using ionic liquids (ILs) and deep eutectic solvents (DESs) have been largely investigated in the past years due to their remarkable applications in different research areas. Herewith we provide an overview on the ILs and DESs used for the preparation of ion gels, highlight the preparation and physicochemical characteristics of stimuli responsive gel materials based on co-polymers and biopolymers, with special emphasis on polysaccharides and discuss their applications. Overall, this review summarizes the fundamentals and advances in ion gels with switchable properties prepared using ILs or DESs, as well as their potential applications in electrochemistry, in sensing devices and as drug delivery vehicles.

Agarose based large molecular systems: Synthesis of fluorescent aromatic agarose amino acid nano-conjugates - their pH-stimulated structural variations and interactions with BSA.

Two new nano-sized fluorescent 6-amino agarose naphthalic acid half ester derivatives were synthesized (ca.60% yields) employing 1,8- and 2,3-naphthalic acid anhydrides (1,8-AANE, and 2,3-AANE respectively). These large nano molecular frameworks (DLS 3 & 100 nm, and 3 & 152 nm respectively) contains amino, naphthalate half-ester carboxyl groups at the C-6 positions of the 1,3-ß-D-galactopyranose moieties of the agarose backbone (overall DS 0.94). Structures were characterized (FT-IR, and 13C &1H NMR spectrometries). These materials mimicked a large protein conjugate (GPC 123, and 108 kDa) exhibiting pH-responsive conformational variations (optical rotatory dispersion), offering a mixed solubility pattern like a soluble random coil (pH 4-10), and precipitate (pH 2) formation. With bovine serum albumin 1,8- and 2,3-AANE showed complexation, and decomplexation at pH 5.2, and 6.8 respectively. However, they showed decomplexation, and complexation respectively at pH 10 (circular dichroism). These fluorogenic systems may be of prospective utility as chiral sensors and in the realms demanding the virtues of preferential protein bindings.

Agarose functionalization: Synthesis of PEG-agarose amino acid nano-conjugate - its structural ramifications and interactions with BSA in a varying pH regime.

In a rapid one-step method protein-mimicking large agarose amino acid framework (AAE; GPC 156.7kDa) was conjugated with polyethylene glycol (PEG 9kDa) affording nano-sized PEGylated amphoteric agarose (PEG-AAE; <10nm; DLS) containing amino, carboxyl and ester groups [overall degree of substitution (DS) 0.91]. The PEG groups were at the residual free carboxylic acid groups of succinate half-ester moiety at C-6 positions of the 1, 3 ß-d-galactopyranose moieties of AAE. This new nano-sized PEG-AAE performed like a giant protein conjugate (GPC 331.2kDa) and exhibited pH-responsive interconversion between the triple helix and single-stranded random structures (optical rotatory dispersion) presenting a mixed solubility pattern like random coil (soluble), helical (soluble) and aggregate (precipitation) formations. Circular dichroism studies showed its pH-dependent complexation and decomplexation with bovine serum albumin (BSA). Such pH-responsive PEG-conjugate may be of pronounced therapeutic potential in the area of pharmacology as well as in sensing applications.

Biomass derived solvents for the scalable production of single layered graphene from graphite.

Among four different biomass derived green and sustainable solvents namely levulinic acid (LA), ethyl lactate (EL), γ-valerolactone (GVL) and formic acid (FA) only LA was found to exfoliate graphite to single and few layered graphene sheets. During exfoliation, the formation of LA crystals embedded with single layered graphene sheets was observed. The process is scalable and the solvent can be recovered and reused in five subsequent cycles of exfoliation for the large scale production of graphene sheets.

Deep eutectic solvents as efficient solvent system for the extraction of κ-carrageenan from Kappaphycus alvarezii.

Three different deep eutectic solvents (DESs) prepared by the complexation of choline chloride with urea, ethylene glycol and glycerol along with their hydrated counterparts were used for the selective extraction of κ-carrageenan from Kappaphycus alvarezii. Upon comparison of the quality of the polysaccharide with the one obtained using water as extraction media as well as the one extracted using widely practiced conventional method, it was found that, the physicochemical as well as rheological properties of κ-carrageenan obtained using DESs as solvents was at par to the one obtained using conventional method and was superior in quality when compared to κ-carrageenan obtained using water as solvent. Considering the tedious nature of the extraction method employed in conventional extraction process, the DESs can be considered as suitable alternative solvents for the facile extraction of the polysaccharide directly from the seaweed. However, among the hydrated and non-hydrated DESs, the hydrated ones were found to be more effective in comparison to their non-hydrated counterparts.

Suitability of bio-based ionic liquids for the extraction and purification of IgG antibodies.

In the past decade, remarkable advances in the production and use of antibodies as therapeutic drugs and in research/diagnostic fields have led to their recognition as value-added proteins. These biopharmaceuticals have become increasingly important, reinforcing the current demand for the development of more benign, scalable and cost-effective techniques for their purification. Typical polymer-polymer and polymer-salt aqueous biphasic systems (ABS) have been studied for such a goal; yet, the limited polarity range of the coexisting phases and their low selective nature still are their major drawbacks. To overcome this limitation, in this work, ABS formed by bio-based ionic liquids (ILs) and biocompatible polymers were investigated. Bio-based ILs composed of ions derived from natural sources, namely composed of the cholinium cation and anions derived from plants natural acids, have been designed, synthesized, characterized and used for the creation of ABS with polypropyleneglycol (PPG 400). The respective ternary phase diagrams were initially determined at 25 °C to infer on mixture compositions required to form aqueous systems of two phases, further applied in the extraction of pure immunoglobulin G (IgG) to identify the most promising bio-based ILs, and finally employed in the purification of IgG from complex and real matrices of rabbit serum. Remarkably, the complete extraction of IgG to the IL-rich phase was achieved in a single-step. With pure IgG a recovery yield of 100% was obtained, while with rabbit serum this value slightly decreased to ca. 85%. Nevertheless, a 58% enhancement in the IgG purity was achieved when compared with its purity in serum samples. The stability of IgG before and after extraction was also evaluated by size exclusion high-performance liquid chromatography (SE-HPLC), sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and Fourier transform infrared spectroscopy (FTIR). In most ABS formed by bio-based ILs, IgG retained its native structure, without degradation or denaturation effects, supporting thus their potential as remarkable platforms for the purification of high-cost biopharmaceuticals.

Preparation of bio-deep eutectic solvent triggered cephalopod shaped silver chloride-DNA hybrid material having antibacterial and bactericidal activity.

2.5% w/w DNA (Salmon testes) was solubilized in a bio-deep eutectic solvent [(bio-DES), obtained by the complexation of choline chloride and ethylene glycol at 1:2 molar ratio] containing 1% w/w of silver chloride (AgCl) to yield a AgCl decorated DNA based hybrid material. Concentration dependent formation of AgCl crystals in the DES was observed and upon interaction with DNA it gave formation of a cephalopod shaped hybrid material. DNA was found to maintain its chemical and structural stability in the material. Further, AgCl microstructures were found to have orderly self assembled on the DNA helices indicating the electrostatic interaction between Ag(+) and phosphate side chain of DNA as a driving force for the formation of the material with ordered microstructural distribution of AgCl. Furthermore, the functionalized material exhibited excellent antibacterial and bactericidal activity against both Gram negative and Gram positive pathogenic bacteria.

Fundamental studies on the feasibility of deep eutectic solvents for the selective partition of glaucarubinone present in the roots of Simarouba glauca.

Several deep eutectic solvents prepared by the complexation of choline chloride as the hydrogen bond acceptor and hydrogen bond donors such as urea, thiourea, ethylene glycol, and glycerol were employed to partition glaucarubinone, an antimalarial compound present in roots of the plant, Simarouba glauca. Among all the solvents, the deep eutectic solvent consisting of the mixture of choline chloride and urea the most suitable to partition the antimalarial compound from the extract selectively. Analytical tools such as high-performance liquid chromatography and electrospray ionization mass spectrometry were used for characterizations, and glaucarubinone extracted from the roots of the plant by conventional solvent extraction method was used as a reference for comparison. The hydrogen and noncovalent bonds formed between glaucarubinone and the deep eutectic solvents could be responsible for the selective partition of the drug molecule.

Agarose based multifunctional materials: evaluation of thixotropy, self-healability and stretchability.

This paper reports a microwave assisted one pot facile synthesis of ester derivatives of agarose (Agr-GAEst) through chemical reaction of agarose (Agr) with gallic acid (GA), an organic acid found in many plants employing carbodiimide chemistry. Agr-GAEst was characterised by FT-IR, (13)C NMR spectroscopy, thermogravimetric analysis (TGA), DMA measurements, scanning electron microscopy (SEM), UV-vis spectrophotometry and rheometry. The native agarose was insoluble in ethylene glycol, but Agr-GAEst (obtained at an optimized molar ratio of 1: 0.5) formed good quality gel (tanδ ∼ 0.1) at 4% (w/v) concentration. The gel thus obtained exhibited substantial degree of thixotropy (hysteresis loop area=38.73%), rapid self-healing ability (12 min) upon complete cleavage of the gel and excellent stretching ability (>20 times of its original length). These types of multifunctional gels would find applications in food and personal health care industries.

A facile approach to prepare a dual functionalized DNA based material in a bio-deep eutectic solvent.

DNA (Salmon testes) was functionalized by Fe3O4 nanoparticles and protonated layered dititanate sheets (H2·Ti2O5·H2O) in a mixture of choline chloride and ethylene glycol (a deep eutectic solvent) to yield a hybrid material having magnetic and antibacterial properties. Ti sheets were found to interact with the phosphate moieties, while Fe interacted with the base pair of DNA in the hybrid material.

Choline chloride-thiourea, a deep eutectic solvent for the production of chitin nanofibers.

Deep eutectic solvents (DESs) consisting of the mixtures of choline halide (chloride/bromide)-urea and choline chloride-thiourea were used as solvents to prepare α-chitin nanofibers (CNFs). CNFs of diameter 20-30 nm could be obtained using the DESs comprising of the mixture of choline chloride and thiourea (CCT 1:2); however, NFs could not be obtained using the DESs having urea (CCU 1:2) as hydrogen bond donor. The physicochemical properties of thus obtained NFs were compared with those obtained using a couple of imidazolium based ionic liquids namely, 1-butyl-3-methylimidazolium hydrogen sulphate [(Bmim)HSO4] and 1-methylimidazolium hydrogen sulphate [(Hmim)HSO4] as well as choline based bio-ILs namely, choline hydrogen sulphate [(Chol)HSO4] and choline acrylate. The CNFs obtained using the DES as a solvent were used to prepare calcium alginate bio-nanocomposite gel beads having enhanced elasticity in comparison to Ca-alginate beads. The bio-nanocomposite gel beads thus obtained were used to study slow release of 5-fluorouracil, an anticancer drug.

Preparation of tamarind gum based soft ion gels having thixotropic properties.

Tamarind gum was used to prepare ion gels using both synthetic ionic liquids (ILs) namely 1-butyl-3-methylimidazolium chloride and 1-butyl-3-methylimidazolium bromide and bio-based ionic liquids (Bio-ILs) namely choline acrylate, choline caproate and choline caprylate by heating cooling process. The gels were found to have good thermal stability and exhibited thixotropic behaviour. Upon relaxation after applied breaking strain, the recovery of gel structures after ten consecutive cycles was observed. The hydrogel of the gum prepared using ethanol aqueous solution had much inferior quality in terms of viscosity, viscoelasticity, thermal stability and thixotropicity when compared with the ion gels. The ion gels also showed very good adherence to human finger muscles and skin. The ion gels thus prepared may find application in electrochemistry, sensors, actuators and the gels prepared with Bio-ILs could even be useful in biomedical applications.