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Two tripodal amides obtained from nitrilotriacetic acid with

On the basis of the boron neutron capture therapy (BNCT) modality, we have designed and synthesized a zinc gallate (ZnGa

Protein–protein interaction in solution strongly depends on dissolved ions and solution pH. Interaction among globular protein (bovine serum albumin, BSA), above and below of its isoelectric point (pI ≈ 4.8), is studied in the presence of anions (Cl(–), Br(–), I(–), F(–), SO(4)(2–)) using small-angle neutron scattering (SANS) technique. The SANS study reveals that the short-range attraction among BSA molecules remains nearly unchanged in the presence of anions, whereas the intermediate-range repulsive interaction increases following the Hofmeister series of anions. Although the interaction strength modifies below and above the pI of BSA, it nearly follows the series.

The molecular mechanism of the heme protein, hemoglobin (Hb) interaction with sulfa molecule, sulfadiazine (SDZ) has been investigated through spectroscopic, neutron scattering and molecular modeling techniques. Absorption and emission spectroscopic studies showed that SDZ molecules were bound to Hb protein, non-cooperatively. The binding affinityof SDZ-Hb complex at standard experimental condition was evaluated to be around (4.2 ± 0.07) ×10

This study scrutinizes the self-association of ethylene oxide (EO)-propylene oxide (PO)-based star-shaped block copolymers as normal Tetronic® (T904) and reverse Tetronic® R (T90R4) with varying molecular characteristics and different hydrophilic-hydrophobic ratios in an aqueous solution environment. These thermo-responsive solutions appear clear, transparent or bluish up to 10%w/v, which anticipated the probable transition of unimers to spherical or ellipsoidal micelles which is complemented by scattering experiments. In a single-solution environment, 10%w/v T904 formed star-shaped micelles at ambient temperature and exhibited a micellar growth/transition with temperature ageing. While 10%w/v T90R4 exists as unimers or a Gaussian coil over a wide range of temperature. Very interestingly, close to the cloud point (CP) flower-shaped spherical and ellipsoidal micelles were formed. A similar proposed micellar scheme was also examined for mixed systems T904 : T90R4 in varying ratios (1 : 0, 3 : 1, 1 : 1, 1 : 3 and 0 : 1) giving an account to the solution behavior of the mixtures. An amalgamation of dynamic light scattering (DLS) and small-angle neutron scattering (SANS) techniques achieved the thorough extraction of the structural parameters of the micellar system. The hydrodynamic diameter (

Plant cell walls undergo multiple cycles of dehydration and rehydration during their life. Calcium crosslinked low methoxy pectin is a major constituent of plant cell walls. Understanding the dehydration-rehydration behavior of pectin gels may shed light on the water transport and mechanics of plant cells. In this work, we report the contributions of microstructure to the mechanics of pectin-Ca gels subjected to different extents of dehydration and subsequent rehydration. This is investigated using a pectin gel composition that forms ‘egg-box bundles’, a characteristic feature of the microstructure of low methoxy pectin-Ca gels. Large Amplitude Oscillatory Shear (LAOS) rheology along with Small Angle Neutron Scattering and Near Infrared (NIR) spectroscopy on pectin gels are used to elucidate the mechanical and microstructural changes during dehydration-rehydration cycles. As the extent of dehydration increase, the reswelling ability, strain-stiffening behavior and the yield strain decreases. These effects are more prominent at faster rates of dehydration and are not completely reversible upon rehydration to the initial undried state. Microstructural changes due to the aggregation of egg-box bundles and single chains and the associated changes in the water configurations lead to these irreversible changes.

Polymer-mediated interactions play an important role in the stability of colloids and are therefore paramount for both fundamental as well as scientific interests. The stability of colloids in the presence of neutral polymers depends on several parameters such as the adsorbing/non-adsorbing nature, molecular weight, concentration and temperature, and such systems are well studied. However, the stability behaviour of charged colloids in the presence of charged polyelectrolyte involves complex interaction mechanisms and hence needs attention. The present work reports the study of the stability behaviour of negatively charged silica colloids in the presence of cationic polyethylenimine (PEI) polyelectrolyte using small-angle neutron and X-ray scattering. The intriguing non-monotonic stability behaviour of silica colloids is observed with varying concentrations of PEI. In the low and intermediate PEI concentration regimes, electrosorption of PEI on the silica colloids causes partial screening of charges, leading to aggregation of colloids. The DLVO interaction potential at low and intermediate concentrations of PEI exhibit a reduced repulsion barrier which is responsible for aggregation. In the high concentration regime, the entropic interaction between the free PEI molecules and PEI decorated silica colloids leads to depletion re-stabilization. The combination of DLVO potential and adsorbed PEI mediated enhanced depletion repulsion in the presence of free PEI gives rise to an increased repulsion barrier responsible for the re-stabilization at high PEI concentrations.

The structures of the complexes of anionic silica nanoparticle (size ∼ 16 nm)-lysozyme (cationic) protein, tuned by the addition of the anionic surfactant sodium dodecyl sulfate (SDS), have been investigated by dynamic light scattering (DLS) and small-angle neutron scattering (SANS). The unique advantage of contrast variation SANS has been used to probe the role of individual components in binary and ternary systems. The cationic lysozyme protein (at pH ∼ 7) adsorbs on the anionic silica nanoparticles and forms mass fractal aggregates due to the strong attractive interaction, whereas similarly charged SDS does not interact physically with silica nanoparticles. The presence of SDS, however, remarkably affects the nanoparticle-protein interactions

Recently the applications of Poloxamers in drug development is promising as it facilitated the drug molecule for delivering to the correct place, at the correct time and in the correct amount. Poloxamers can form nanomicelles to encapsulate hydrophobic drugs in order to increase solubility, stability and facilitate delivery at target. In this context, the solubilization of anticonvulsant lamotrigine (LMN) drug in a chain of Poloxamers containing different polyethylene oxide and polypropylene oxide noieties were examined. The results showed better solubilization of LMN in Poloxamers contain low CMTs while poor with Poloxamers having high CMTs. Systematic investigation of two mixed Poloxamer nanomicelles (P407:P403 and P407:P105) for LMN bioavailability at body temperature (37 °C) were investigated. The solubility of LMN was enhanced in mixed P407:P403 nanomicelles with the amount of P403 and reduced in mixed P407:P105 nanomicelles with the amount of P105. LMN encapsulated mixed Poloxamer nanomicelles were found spherical in shape with ~25 nm Dh sizes. The In-Vitro release profiles of mixed Poloxamer nanomicelles demonstrated the biphasic model with initial burst release and then slowly release of LMN. Better biocompatibility of LMN in the mixed P407:P403 nanomicelles was confirmed with stability data. The results of this work were proven the mixed P407:P403 nanomicelles as efficient nanocarriers for LMN.

Quercetin (QCN) is a plant polyphenol with a variety of medicinal effects. Poor water solubility, on the other hand, restricts its therapeutic effectiveness. The purpose of this study was to develop mixed micellar systems using two biocompatible amphiphilic PEO-PPO-PEO triblock copolymers, Pluronic P123 (EO20-PO70-EO20) and Pluronic F88 (EO104-PO39-EO104), in order to enhance the aqueous solubility and oral bioavailability of QCN drug. The critical micelle concentrations (CMCs) of mixed P123/F88 micellar solutions were investigated using UV–visible spectroscopy with pyrene as a probe. Mixed P123/F88 micelles have low CMCs, indicating that they have a stable micelle structure even when diluted. The solubility of QCN in aqueous mixed P123/F88 micellar solutions at different temperatures was investigated to better understand drug entrapment. The QCN solubility increased with increasing temperature in the mixed P123/F88 micellar system. The QCN-incorporated mixed P123/F88 micelles were prepared using the thin-film hydration method and were well characterized in terms of size and morphology, compatibility, in vitro release and antioxidant profile. In addition, the cell proliferation activity of the mixed micelles was evaluated in the MCF-7 cell line. The QCN-incorporated mixed P123/F88 micelles had a small particle size (

Lipophile induced modulations of self-assembly characteristics in aqueous Pluronic systems merit attention because of wide-ranging uses of Pluronics as solubilizing agents of lipophilic substances. In this paper, we report unusual evolutions of structural and hydration properties in lavender essential oil (LO) solubilized Pluronic P85 aqueous micellar systems as a function of micellar volume fraction and temperature. Our DLS, SANS, and viscometry studies show that the spherical-to-wormlike micellar structural transition observed in 1% P85 solutions upon solubilization of LO quite unexpectedly gets suppressed with increased P85 concentration to ≥5%. Detailed SANS studies reveal that the core sizes of the oil solubilized micelles cannot attain the threshold value required for the onset of structural transition at higher copolymer concentrations due to their progressive shrinking with an increase in P85 concentration. Oil solubilized P85 solutions show two cloud points and very interestingly exhibit micellar growth upon cooling to their lower cloud points. Steady state fluorescence studies explain this based on increasing dehydration of micellar corona with a decrease in temperature, very much opposite to what is observed in pure aqueous Pluronic systems. The results give new insight into viscous flow properties and low temperature storage possibilities of oil solubilized aqueous Pluronic systems.

We report intermolecular gelation of deoxyribonucleic acid (DNA) and folic acid (FA, 1% (w/v) and DNA, 0.1–0.5% (w/v)) in Dimethyl Sulfoxide (DMSO)-water solution despite both having similar net ch...

Poly(ethylene oxide, EO)-poly(propylene oxide, PO)-poly(ethylene oxide, EO)-based triblock copolymers (BCPs) with 80% hydrophilicity stay molecularly dissolved as Gaussian chains at ambient temperature, even at fairly high concentrations (5 %w/v). This study presents the plausible micellization behaviour of such very-hydrophilic Pluronics® - F38, F68, F88, F98, and F108 - incited upon the addition of glucose at low concentrations and temperatures. The outcomes obtained from phase behaviour and scattering studies are described. At temperatures near to ambient temperature, these BCPs form micelles with a central core made of a PO block, surrounded by a corona of highly hydrated EO chains. The phase transitions in these hydrophilic Pluronics® in the presence of glucose are demonstrated

Nanofluids have gained recent attention because of their potential applications in diverse engineering fields like enhancing thermal transport, particle deposition, coating, surface patterning, etc. Stability of nanofluid is vital for their use in these industrial applications, although the pertinent database in the literature is often inadequate. Herein, we investigate the effect of surfactant concentration and particle solid volume fraction (φ) on stability of Ti- and Al-oxide nanoparticle suspensions that are stabilized with different surfactants. While TiO2-AA, TiO2-CTAB nanofluids are found to have appreciable stability, SDBS-stabilized Al2O3 nanofluid shows otherwise. TEM images provide the morphological characteristics of freshly prepared nanofluids, whereas the data of DLS and ZP are used to describe the nanofluid particle size distribution and stability, respectively. SANS data confirm the formation of the different sized particles for all the nanofluids. Surface tension (ST) and contact angle (CA) of the prepared nanofluids have also been reported. Results show that the sessile droplet CA of a surfacted-water solutions decreases as more and more nanoparticles are added in the suspension. ST measurements corroborate with the CA measurements, where the nanofluid ST is found to decrease with increase in solid volume fraction (φ) and temperature. Time-lapse images indicate that the settling behaviour of Al2O3-water nanofluids changes with φ and surfactant ratios, but the TiO2-water nanofluids show consistent stability for all φ and surfactant ratios. The reported trend of variation of the mean deposition fraction per unit time with φ for different surfactant ratios helps in making better choice of surfactant ratio for individual φ.

The mixture of the cationic surfactant, cetyltrimethylammonium bromide (CTAB), and anionic surface-active ionic liquid, 1-butyl-3-methylimidazoliumdodecyl sulfate (bmimDS), has been studied as a function of the mole fraction of CTAB, XCTAB, with the total surfactant concentration fixed at 50 mM using turbidity measurements, rheology, dynamic light scattering, differential scanning calorimetry, small-angle neutron scattering, and small-angle X-ray scattering techniques. The catanionic mixture has been found to exhibit phase transitions from vesicles to micelles as a function of temperature, with some mole fractions of CTAB showing dual transitions. Solutions of XCTAB = 0.2 to 0.5 exhibited a single transition from vesicles to cylindrical micelles at 45 °C. With an increase in the mole fraction of CTAB from 0.55 to 0.65, dual structural transitions at 30 and 45 °C were observed. The microstructural transition at 30 °C is ascribed to the vesicle aggregation process with smaller vesicles fusing into bigger ones, whereas the transition at 45 °C was evaluated to be the vesicle-to-cylindrical micelle transition. However, at higher mole fractions of CTAB, XCTAB from 0.65 to 0.90, a single transition from vesicles to small cylindrical/spherical micelles was observed in the solutions, at a lower temperature of 30 °C. To the best of our knowledge, such a microstructural transitions as a function of temperature in a single mixture of cationic and anionic surfactants without any additive has not been reported so far.

Graphene oxide (GO) nanosheet suspension is not stable in physiological ionic fluids. To improve stability, surfactants such as Pluronic 103 (P103) have been tested. Going further, this work investigated whether conferring positive surface charge to the surfactant may improve the adsorption ability of P103 micelles on GO sheets. Positive charge on the surfactant was induced by adding dodecyltrimethylammonium bromide (DTAB, a cationic surfactant) in P103 micelles. Subsequent changes in aggregation parameters were investigated through dynamic light scattering and small-angle neutron scattering studies. DTAB incorporation was accompanied by a steady increase in the ζ potential and mixed micelle formation. At high surface charge density, the interaction between adjacent head groups was distorted, which led to dissociation of mixed micelles. Structural developments during the adsorption of mixed micelles on the sheet surface (mass fractal formation) were monitored in terms of changes in the scattering features of aggregates. These fractals emerged as a result of electrostatic interactions. Our observations point toward the existence of small-sized building blocks at low DTAB concentration (≤4 mM). With a superior adsorption, mixed micelles are expected to occupy the intersheet space and maintain a hydration layer. However, at a higher DTAB concentration (≥10 mM), micelles dissociate to produce DTAB-rich unimers and P103-rich loose aggregates. At this point, sheets tend to aggregate in the solvent, regardless of fractal formation.

We elucidate the influences of hydration on the morphological heterogeneity of the class of hard-soft segmented copolymers by experimenting on three model members selected from this group. For influences on phase segmentation, we quantify the degree of phase separation, segment boundary diffusiveness and extent of interphase mixing. Qualitative variations induced by hydration in hydrogen bonding within the phases are also mapped. An inverse relationship between the degree of segmentation and inherent water miscibility of the polymer backbones is observed, that is, high miscibility reducing the degree of segmentation, whereas poor miscibility increasing it. We then quantify hydration induced variations in the size, volume fraction and interaction pair potentials of individual hard segments. The influences on hard segment assemblies are assessed by quantifying their size, volume fraction, interaction pair potential and intrasegment adhesion. This quantification reveals a complex interplay between the volume expansion of individual hard segments and simultaneous swelling and disassembly of their assemblies. Finally, we integrate the segmentation parameters with observed alterations in hydrogen bonding and the inherent polarizability of segments to present a mechanism that reasonably describes the hydrated state morphology. Besides revealing the influences of hydration on the morphological heterogeneity of this class of polymers, our insights give strategies for new synthesis methods for water contact applications and aids in predicting their hydration induced thermomechanical property alterations.

The interaction of a bovine serum albumin (BSA) protein with the mixture of anionic sodium dodecyl sulfate (SDS) and cationic dodecyltrimethylammonium bromide (DTAB) has been investigated by small-angle neutron scattering (SANS) and dynamic light scattering (DLS). Both SDS and DTAB as individuals interact electrostatically as well as hydrophobically with BSA and form connected protein-decorated micelle like complexes in the aqueous solution, in which the well-defined surfactant micelles are organized along the randomly distributed unfolded polypeptide chain of the protein. The protein-surfactant interaction has been tuned by adding different molar mixtures of SDS and DTAB in BSA aqueous solution. It is found that a lower molar fraction of either surfactant in the protein-mixed surfactant complexes results in the formation of a connected protein-decorated micelle structure similar to those of pure surfactants. As the molar fraction of one of the surfactants in the mixture approaches the equimolar fraction, the structure formed by the protein-mixed surfactant is very different from the connected protein-decorated micelle like structure. Different microstructures of BSA-mixed surfactant complexes are formed, mostly governed by the structure of mixed surfactants arising from the strong electrostatic interaction of oppositely charged components. In this case, unfolded proteins wrap the structures of mixed surfactants around their surface. Along with the connected protein-decorated micelle like structure, rod-like and bilayer vesicles of protein-surfactant complexes are formed at different molar fractions of mixed surfactants.

Chain collapse in synthetic polymers is an excellent approach for mimicking the natural self-folding process that imparts structural control, leading to attractive compartmental applications, e.g. drug delivery. In this regard, water-soluble and thermo-responsive polyacrylamide polymers CP1–2 with photodimerizable coumarin moieties grafted into the backbone are employed to design polymeric nanoparticles. The chain collapse can be efficiently controlled using dual response strategies involving photodimerization under UVB light (λmax = 320 nm) as well as host–guest interaction by the addition of a bis-β-CD host. The aggregation of the nanoparticles is controlled by the interplay of a lower critical solution temperatures (LCST) that can be tuned as a result of photodimerization and host–guest interaction. Further, sequential folding of the polymers is demonstrated by the addition of the host molecule followed by exposure to UVB irradiation. Such multi-stimuli-responsive compaction of size with synergistic control of non-covalent and dynamic covalent interaction and tuning of LCST render the system suitable for compartmental loading and sustainable/burst release of hydrophilic and hydrophobic cargos e.g. rhodamine B dye and the drug ibuprofen under homeostasis control.

Silk fibroin (SF) hydrogels find wide applications in tissue engineering. However, their scope has been limited due to the long gelation time in ambient conditions. This paper shows the reduction in gelation time of silk fibroin to minutes upon doping with a newly synthesized lauric acid sophorolipid (LASL). LASL comprises a fatty acid, lauric acid (with a 12-carbon aliphatic chain), that is derivatized by glucose molecules using a non-pathogenic yeast Candida bombicola. LASL was characterized using spectroscopic (Fourier transform infrared spectroscopy) and chromatographic (high-performance liquid chromatography, thin-layer chromatography, and high-resolution mass spectrometry) methods. This gelation of SF is comparable to the effect of an anionic surfactant, sodium dodecyl sulfate (SDS). The microstructure of SF-LASL hydrogels was investigated by small-angle neutron scattering (SANS) measurements and exhibited the beads-on-a-necklace model. The rheological properties of these hydrogels show similarity to SF-SDS hydrogels, therefore presenting a greener alternative for tissue engineering applications.

Deep eutectic solvents (DES) have revealed the ability to promote the aggregation of amphiphiles in solution. With a brief overview on the self-assembly of amphiphilic substances in protic/aprotic, polar/non-polar solvents, ionic liquids (ILs), and deep eutectic solvents, we herein report the aggregation behavior of a star block (4-arm) ethylene oxide (EO)-propylene oxide (PO) block copolymer (5 %w/v) tetronic T1304 in the presence of different DESs [ChCl: urea, ChCl: ethylene glycol (EG), ChCl: glycerol (Gly), ChCl: malonic acid (MA), ChCl: glutaric acid (GA), and ChCl: oxalic acid (OA)] in varying aqueous molar ratio solution. From high-sensitivity differential scanning calorimetry (HSDSC), surface tension (S.T.), small-angle neutron scattering (SANS), and dynamic light scattering (DLS), we present for the first time the self-aggregation and size distribution profile of amphiphilic tetronic T1304 in DES-water mixture system. The solubility of poorly water-soluble drug, quercetin (QN), was also checked in 5 %w/v copolymeric micelles and in presence of different DESs using UV-Visible spectroscopy. The presence of various DESs alter the micellization and micellar characteristics and such observed behavior are due to the favorable interactions that support the self-assembly in DES-water solvent mixture which is further elucidated by the molecular simulation study using the Gauss View 5.0.9.

Metacomposites are an interesting field of research. This research is regarding tunable magnetic metacomposite formed using graphene and polyethylene (PE). Dielectric measurements show that as the concentration of graphene was increased in PE–graphene nanocomposites, the separation between graphene sheets decreased and negative dielectric constant was observed at low frequencies while high dielectric constant was observed at high frequencies of the applied field. The switching frequency could be controlled by changing the graphene concentrations. Small angle neutron scattering (SANS) analysis showed that the graphene assembled as fractals in the nanocomposites. As more graphene was incorporated into the nanocomposites, the fractals gave rise to percolation. We propose that the fractals are the building blocks for percolation phenomenon in the PE–graphene nanocomposites. Also, we observed ferromagnetism in the PE–graphene nanocomposites till 30% graphene. At 40% graphene the nanocomposite becomes a diamagnet. We attribute this to the topological defects induced in graphene by PE. Theses PE–graphene magnetic meta composites can have potential applications in battery technology.

This research paper demonstrates the synthesis of zero-dimensional (0D) porous cupric oxide (CuO) nanoparticles by two different methods i.e. reflux and precipitation, followed by calcinations at different temperatures starting from 350 to 550 °C with an increment of 100 °C. The synthesized materials when calcined at different temperatures not only retain their structure, but also improve the crystalline nature. The maximum mean pore radius is found to be 4.15 nm for the sample calcined at 550 °C, synthesized by reflux technique, which is confirmed through SANS studies. The Cu (II)-O bond has been recorded in the range of 400 to 600 cm−1 and the peak of Cu-O has been observed at 603 cm−1 which is analyzed through FTIR spectra. The optical band gap of CuO is estimated to be 1.8 eV by diffused reflectance spectroscopic studies which indicate that the synthesized CuO nanoparticles are good photo-catalysts for phenol degradation within the wavelength range of visible-light. However, the polydispersity of the calcined materials gradually decreases with increase in temperature. It has been found from the Hall measurement that the synthesized CuO material is p-type in nature and I–V characteristics are linear in nature. As the Ohmic current mechanism is dominant, therefore the synthesized CuO material is an ideal candidate for sensor applications. The electrical conductivity of the CuO nanoparticles enhances when the measurement has been carried out in presence of phenol. It is seen that 450 °C calcined CuO shows highest degradation efficiency of phenol (98%) and phenol sensing.

A ubiquitous example of DNA and proteins inspires the scientific community to design synthetic systems that can construct various self-assembled complex nano-objects for high-end physiological functions. To gain insight into judiciously designed artificial amphiphilic structures that through self-assembling form various morphological architectures within a single system, herein, we have studied self-aggregation of amide-functionalized surface-active ionic liquids (AFSAILs) with different head groups in the DMSO/water mixed system. The AFSAIL forms stimuli-responsive reversible micelle and vesicle configurations that coexist with three-dimensional (3D) network structures, the organogel in the DMSO/water mixed system. The self-assembly driving forces, self-organization patterns, network morphologies, and mechanical properties of these network structures have been investigated. With the proven biodegradability and biocompatibility, one can envisage these AFSAILs as the molecules with a new dimension of versatility.

This work focuses on dielectric measurements and small-angle neutron scattering (SANS) analysis of polyurethane–graphene nanocomposite that is conducting and of low density. In this research graphene nanoplatelets were used. Polyurethane and graphene were mixed in appropriate weight proportions to make polyurethane–graphene (PU–graphene) nanocomposites. The porosity is decreased with an increase in graphene concentration. The dielectric characteristics such as dielectric constant, dielectric loss, loss tangent, and electric modulus were influenced by the graphene concentration. The conductivity (S/cm) increased rapidly by (~ 4 × 109 times) when the graphene concentration was increased to 30% and it indicates the formation of conducting pathways at high concentrations of graphene. SANS analysis showed that polyurethane has micellar structure and graphene assembles as fractals in the foams leading to conduction pathways in the nanocomposites. This research could benefit creation of lightweight materials for electronics.

The structure of core-shell micelles formed by nonionic surfactant Triton X-100 (TX-100) in a supercooled glucose-urea melt is investigated by contrast variation small-angle X-ray scattering (SAXS), small angle neutron scattering (SANS), and HR-TEM. Cooling a molten mixture of glucose-urea (weight ratio of 3:2) to room temperature yields a supercooled solvent without crystallization that can be used for trapping micelles of TX-100. By use of a combination of water and glucose-urea mixture at different proportions as solvent for micellization, the scattering length density (SLD) of the solvent can be tuned to match the shell contrast of the micelles. A systematic analysis of SAXS and SANS data with different SLD of solvent permits a quantitative evaluation of electron density profile of micelles in different matrices. The core of TX-100 micelles shows significant swelling in glucose-urea melt, as compared to that in water. The dimension and morphology of micelles were evaluated by scattering techniques and HR-TEM. Dynamic light scattering (DLS) studies suggest that, unlike micelles in water, the diffusion of micelles in supercooled glucose-urea melt decreased by several orders of magnitude.