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Browsing by Author "Mata, JP"

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3D printed graphene aerogels using conductive nanofibrillar network formulation
(Elsevier, 2023-06) Tran, TS; Balu, R; Mata, JP; Dutta, NK; Choudhury, NR
Despite recent progress in 3D printing of graphene, formulation of aqueous 3D printable graphene inks with desired rheological properties for direct ink writing (DIW) of multifunctional graphene macrostructures remains a major challenge. In this work, we develop a novel 3D printable pristine graphene ink in aqueous phase using conductive nanofibrillar network formulation by controlling the interfacial interactions between graphene and PEDOT:PSS nanofibrils. The formulated inks, tailored for energy applications, provide excellent 3D printability for fabricating multilayer 3D structures (up to 30 layers) with spanning features and high aspect ratio. The 3D printed aerogels, comprising interconnected networks of graphene flakes and PEDOT:PSS nanofibrils, exhibit excellent electrical conductivity as high as ∼630 S m − 1 and can be converted into conductive hydrogels via swelling in water/electrolyte. The formulated graphene inks were used for fabricating 3D printed supercapacitor electrodes (power density of 11.3 kW kg−1 and energy density of 7.3 Wh kg−1) with excellent performance and durability. © 2023 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license.
Application of small angle scattering (SAS) in structural characterisation of casein and casein-based products during digestion
(Elsevier, 2023-07) Bayrak, M; Mata, JP; Conn, CE; Floury, J; Logan, A
In recent years, small and ultra-small angle scattering techniques, collectively known as small angle scattering (SAS) have been used to study various food structures during the digestion process. These techniques play an important role in structural characterisation due to the non-destructive nature (especially when using neutrons), various in situ capabilities and a large length scale (of 1 nm to ∼20 μm) they cover. The application of these techniques in the structural characterisation of dairy products has expanded significantly in recent years. Casein, a major dairy protein, forms the basis of a wide range of gel structures at different length scales. These gel structures have been extensively researched utilising scattering techniques to obtain structural information at the nano and micron scale that complements electron and confocal microscopy. Especially, neutrons have provided opportunity to study these gels in their natural environment by using various in situ options. One such example is understanding changes in casein gel structures during digestion in the gastrointestinal tract, which is essential for designing personalised food structures for a wide range of food-related diseases and improve health outcomes. In this review, we present an overview of casein gels investigated using small angle and ultra-small angle scattering techniques. We also reviewed their digestion using newly built setups recently employed in various research. To gain a greater understanding of micro and nano-scale structural changes during digestion, such as the effect of digestive juices and mechanical breakdown on structure, new setups for semi-solid food materials are needed to be optimised. © 2023 Elsevier Ltd
Application of time-resolved small angle neutron scattering to non-equilibrium kinetic studies
(Springer Nature, 2011-11-15) Mata, JP; Hamilton, WA; Gilbert, EP
Small-angle neutron scattering (SANS) provides structural information on the length scale from one to several hundred nanometres. Time-resolved SANS measurements (TR-SANS) therefore yield kinetic information on the evolution from one quasi-static structure to another. The technique offers complementary information to neutron spectroscopic methods where the focus is dynamics. Approaches for maximising time resolution in SANS are described, along with the particular advantages of neutrons, and some recent examples are discussed. © 2023 Springer Nature
Chemomechanical influences during replacement of limestones by siderite
(Goldschmidt, 2022-07-15) Weber, J; Starchenko, V; Zhang, R; Ilavsky, J; Debeer-Schmidt, L; Mata, JP; Littrell, K; He, L; Chen, WR; Allard, LF; Stack, AG; Anovitz, L
A fundamental and predictive understanding of mineral-fluid interactions is important for a wide range of energy topics including carbon sequestration, nuclear waste management and legacy contamination clean up. The properties of aqueous solution are altered by confinement, which can be present within natural geomaterials, e.g., in grain boundaries and nanopores. Mineral replacement reactions have been reported to proceed via grain boundaries possibly due to higher diffusion rates than in solids. In addition to confinement effects, chemomechanical effects such as crystallization pressure induced fracturing can also alter mineral-fluid interactions. To test the effects of porosity and grain boundaries on replacement in single component and impurity-containing systems we experimentally investigated the model system of limestone replacement by siderite by batch reactor experiments at 200°C from 2 to 120 days with FeCl2. Variation in initial microstructure and solid impurities were used to identify reaction controls. Changes in porosity were spatially resolved analyzed using inverse scattering techniques ((ultra) small angle neutron/X-ray scattering), and these were combined with imaging by scanning (SEM) and transmission electron microscopy (TEM). In high-porosity limestones replacement is rapid (complete replacement within 2 days), and transport controlled, whereas in low-porosity limestones elevated porosity throughout the whole rock volume was observed that was independent of the reaction rim. Image analysis showed widening of selected grain boundaries with increasing reaction time. This led to increased grain boundary width distributions that were observed as higher porosity by scattering methods. SEM imaging showed that nucleation of siderite crystals either at dolomite impurities within the limestone or other defects lead to exertion of crystallization pressure, widening grain boundaries, which led to formation of preferential transport pathways that limited replacement of solid impurity-containing limestone rocks. This highlights how chemomechanical effects can alter reaction pathways.
Clouding behaviour of PEO-PPO based triblock copolymers in aqueous ionic surfactant solutions: a new approach for cloud point measurements
(Elsevier, 2010-05-15) Patel, T; Bahadur, P; Mata, JP
The cloud points (CP) of 1 g/dl solutions of polyethylene oxide–polypropylene oxide (PEO–PPO) based triblock copolymers (Pluronics® P84, L64, L44 and Reverse Pluronics® 10R5, 25R4, 17R4) were measured as a function of their molecular weight and added ionic surfactant. For identical PEO/PPO ratios, copolymers with lower molecular weight show a larger increase in the cloud point in the presence of surfactants than polymers with higher molecular weight. The opposite trend has been observed for reverse Pluronics. The cloud points of polymers with different PEO/PPO ratios have also been reported. An increase in the size of the middle PEO block in reverse Pluronics has a more significant effect on cloud points than molecular weight increment. Ionic surfactants produced marked increases in the cloud points of copolymer solutions. The effect was much larger for surfactants with higher hydrophobicity. Cationic surfactants with different chain lengths were used to examine the surfactant–polymer interaction. A novel approach for normalising the cloud points to their relative values has been carried out to see the clear effect of ionic surfactants. Tri component systems, comprising polymers, cetyltrimethylammonium bromide (C16TABr) surfactant and salt (NaBr), have also been studied to see the effect of salt on the phase separation behaviour of solutions within the framework of our new cloud point approach. © 2010, Elsevier Ltd.
Clustering of charged colloidal particles in the microgravity environment of space
(Springer Nature, 2023-04-29) Miki,.H.; Ishigami, T; Yamanaka, J; Okuzono, T; Toyotama, A; Mata, JP; Komazawa, H; Takeda, Y; Minami, M; Fujita, M; Doi, M; Higuchi, T; Takase, H; Adachi, S; Sakashita, T; Shimaoka, T; Nagai, M; Watanabe, Y; Fukuyama, S
We conducted a charge–charge clustering experiment of positively and negatively charged colloidal particles in aqueous media under a microgravity environment at the International Space Station. A special setup was used to mix the colloid particles in microgravity and then these structures were immobilized in gel cured using ultraviolet (UV) light. The samples returned to the ground were observed by optical microscopy. The space sample of polystyrene particles with a specific gravity ρ (=1.05) close to the medium had an average association number of ~50% larger than the ground control and better structural symmetry. The effect of electrostatic interactions on the clustering was also confirmed for titania particles (ρ ~ 3), whose association structures were only possible in the microgravity environment without any sedimentation they generally suffer on the ground. This study suggests that even slight sedimentation and convection on the ground significantly affect the structure formation of colloids. Knowledge from this study will help us to develop a model which will be used to design photonic materials and better drugs. © 2023 The Authors, Open Access under a Creative Commons Attribution 4.0 International License. Published in cooperation with the Biodesign Institute at Arizona State University, with the support of NASA.
Combined pressure and temperature denaturation of ribonuclease A produces alternate denatured states
(Elsevier, 2016-05-13) Ryan, TM; Xun, Y; Cowieson, NP; Mata, JP; Jackson, AJ; Pauw, BR; Smith, AJ; Kirby, N; McGillivray, DJ
Protein folding, unfolding and misfolding have become critically important to a range of health and industry applications. Increasing high temperature and high pressure are used to control and speed up reactions. A number of studies have indicated that these parameters can have a large effect on protein structure and function. Here we describe the additive effects of these parameters on the small angle scattering behaviour of ribonuclease A. We find that alternate unfolded structures can be obtained with combined high pressure and temperature treatment of the protein. © 2016 Elsevier Inc.
Corrigendum to “Application of chelating weak base resin Dowex M4195 to the recovery of uranium from mixed sulfate/chloride media” [Chem. Eng. J., 317 (2017) 80–89]
(Elsevier, 2017-09-15) Ogden, MD; Moon, EM; Wilson. A; Griffith, CS; Mata, JP; Soldenhoff, KH; Pepper, SE
The authors regret that the historical contributions from collaborators at ANSTO were not sufficiently acknowledged in this paper. The authors would like to add the following contributors, with the affiliations shown above. The acknowledgements should also state the following; “The authors would like to acknowledge the members of the Separations and Nuclear Chemical Engineering Research (SNUCER) group at the University of Sheffield who all assisted with this work in some capacity. Thank you to Prof. Neil Hyatt and Dr. Claire Corkhill in MIDAS, University of Sheffield for use of analytical equipment. Thank you to Dr. Gabriella Kakonyi at the Kroto Research Institute at the University of Sheffield for ICP-MS analysis. Funding was provided by the Department of Chemical and Biological Engineering at The University of Sheffield, as part of their start-up scheme. This work is published with the permission of the Australian Nuclear Science & Technology Organisation, where most of the work was conducted.” The authors would like to apologise for any inconvenience caused. © 2017 Elsevier B.V
Deuterium effects in human serum albumin with nanoparticle silica kinetics
(Australian Institute of Nuclear Science and Engineering, 2016-11-29) White, JW; Raynes, JK; Mata, JP; Gilbert, EP; Knott, RB; de Campo, L
Light scattering shows three stages of the interaction of 80Å radius silica nanoparticles with human serum albumin in buffered solutions. The structures formed in the fast stage, twenty minutes after mixing, have been identified in a “stopped flow” neutron small angle scattering experiment. Good scattering functions were obtained at two-minute time resolution for this phase of the interaction in D2O and H2O. pH dependent changes in structure are analysed using standard fitting programs with a minimum number of parameters. This experiment was aimed to find the structural signature of nanoparticle-protein interaction, possibly the “protein corona” supposed to be formed as a means to promote entry of nanoparticles into cells. Here we use small “engineered” nanoparticles where the indications of toxicity are strong. We show with nanometric resolution that for our system, the association is largely a form of protein-induced aggregation distinct from the protein corona hypothesis. The corona might well be the mode of interaction for small proteins and nanoparticles 10-100 times larger than we have studied, but measurements on widely used commercial products may be more relevant.
Direct in situ determination of the surface area and structure of deposited metallic lithium within lithium metal batteries using ultra small and small angle neutron scattering
(Wiley, 2023-10-10) Didier, C; Gilbert, EP; Mata, JP; Peterson, VK
Despite being the major cause of safety and performance issues in lithium metal batteries, experimental difficulties in quantifying directly the morphology of lithium deposited at electrode surfaces have meant that the mechanism of metallic lithium growth within batteries remains elusive. This study demonstrates that quantitative detail about the morphology of metallic lithium within batteries can be derived non-destructively and directly using in situ ultra-small and small-angle neutron scattering. This information is obtained over a large electrode area in cells where lithium deposition processes are typical of real-world applications. Complex variations of surface area and interfacial distances 1–10 µm and 100–300 nm are revealed in size that are influenced by current density and cell cycling history, providing valuable insight into the growth of metallic lithium features detrimental to battery performance. Such quantitative insight into the process of lithium growth is required for the development of safer high-performance lithium metal batteries. © 2023 Commonwealth of Australia. Advanced Energy Materials published by Wiley-VCH GmbH. This is an open access article under the terms of the Creative Commons Attribution License.
Divergent Fe and S mineralization pathways during the oxidative transformation of greigite, Fe3S4
(Elsevier, 2017-09-30) Moon, EM; Bush, RT; Gibbs, DHM; Mata, JP
The iron sulfide mineral greigite, Fe3S4, has previously been identified in the surface layers of the intertidal zone of a partially remediated acid sulfate soil wetland, representing an end-member in an iron sulfide mineralization pathway distinct from that of pyrite. The persistence of greigite is important for the stability of the remediated landscape, but the response of greigite to periods of oxygenation (for example, during a neap tide) is poorly understood. In this study, we employ X-ray absorption spectroscopy to identify the Fe and S speciation and mineralogy resulting from the oxidative disintegration of synthetic greigite under physiochemical solution conditions consistent with a partially remediated acid sulfate soil wetland. Results indicate divergent Fe and S mineralization pathways culminating in elemental sulfur and iron (hyr)oxide minerals. No sulfate-containing minerals were identified, and under all conditions tested, residual greigite remains. The oxidation products, and the presence of sulfur reducing bacteria, provide the right chemical environment for the reformation of greigite during the sub-oxic conditions of the rest of the tidal cycle. This likely explains the persistence of greigite in the intertidal zone, and implies that the oxidation of greigite is not detrimental to the long term stability of the acid sulfate soil remediation process. © 2017 Elsevier B.V.
Effect of 1-alkanols/salt on the cationic surfactant micellar aqueous solutions-A dynamic light scattering study
(Elsevier, 2011-05-05) Kuperkar, KC; Mata, JP; Bahadur, P
The effect of 1-alkanols viz., ethanol, 1-butanol and 1-hexanol on five quaternary salts based cationic surfactants in water and in presence of 0.1 M salts has been systematically investigated by viscosity and dynamic light scattering (DLS) technique. The concentration for surfactant varying in non-polar tail, polar head and counterion was kept constant (similar to 50 mM) throughout. The viscosity data are less detailed, but confirm the general trend of micellar growth and transitions. Influence of 1-butanol on critical micelle concentration (CMC) and degree of counterion dissociation (alpha) was also investigated conductometrically. These measurements were done to supplement the role of counterions in exploring the binding phenomenon due to the effect of salt and alcohol during micellization. The effect of 1-alkanols upon the viscosity and micelle hydrodynamic diameter (D-h) of micelles in the presence of salt at varying concentration and temperature was also examined in detail to explain the hydrophobic interactions and electrostatic effects. (C) 2011 Elsevier B.V.
Effect of temperature on the conformation and functionality of poly(N-isopropylacrylamide) (PNIPAM)-grafted nanocellulose hydrogels
(Elsevier, 2023-12-15) Raghuwanshi, VS; Mendoza, DJ; Browne, C; Ayurini, M; Gervinskas, G; Hooper, JF; Mata, JP; Wu, CM; Simon, GP; Garnier, G
Hypothesis Poly(N-isopropylacrylamide) [PNIPAM]-grafted cellulose nanofibers (CNFs) are new thermo-responsive hydrogels which can be used for a wide range of applications. Currently, there is no clear understanding of the precise mechanism by which CNFs and PNIPAM interact together. Here, we hypothesize that the physical crosslinking of grafted PNIPAM on CNF inhibits the free movement of individual CNF, which increases the gel strength while sustaining its thermo-responsive properties. Experiments The thermo-responsive behaviour of PNIPAM-grafted CNFs (PNIPAM-g-CNFs), synthesized via silver-catalyzed decarboxylative radical polymerization, and PNIPAM-blended CNFs (PNIPAM-b-CNFs) was studied. Small angle neutron scattering (SANS) combined with Ultra-SANS (USANS) revealed the nano to microscale conformation changes of these polymer hybrids as a function of temperature. The effect of temperature on the optical and viscoelastic properties of hydrogels was also investigated. Findings Grafting PNIPAM from CNFs shifted the lower critical solution temperature (LCST) from 32 °C to 36 °C. Below LCST, the PNIPAM chains in PNIPAM-g-CNF sustain an open conformation and poor interaction with CNF, and exhibit water-like behaviour. At and above LCST, the PNIPAM chains change conformation to entangle and aggregate nearby CNFs. Large voids are formed in solution between the aggregated PNIPAM-CNF walls. In comparison, PNIPAM-b-CNF sustains liquid-like behaviour below LCST. At and above LCST, the blended PNIPAM phase separates from CNF to form large aggregates which do not affect CNF network and thus PNIPAM-b-CNF demonstrates low viscosity. Understanding of temperature-dependent conformation of PNIPAM-g-CNFs engineer thermo-responsive hydrogels for biomedical and functional applications. © 2023 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license.
The effects of Bi addition on the mechanical properties of eutectic Sn-Ag-Cu lead-free solder alloy
(Australian Institute of Nuclear Science and Engineering (AINSE), 2020-11-11) Olofinjana, A; Shewchenko, L; Mata, JP; Haque, R
Sn-Ag-Cu (SAC) solders are gaining momentum as the choice of Pb free electrical interconnect materials because of the legislative restrictions on the use of hazardous materials in electronic devices. However, SAC has high melting temperatures around 217oC. The role of Bi substitution to lowering solder joint processing temperatures are widely considered because of the low-temperature Sn-Bi eutectic. However, the embrittling effects of Bi addition require clarification on the maximum limits of substitution. In this work, the mechanical properties of eutectic SAC with gradual Bi substitution up to 10wt.% Bi was followed. It is shown that fracture strength (σ_f) increases from 50MPa plateauing at 60MPa between 1.4 and 1.8%Bi representing the limits of solid solution strengthening. Over this substitution range, strain at fracture (ε_f) dropped from 30% to 10% and reduction in area (RA) dropped from 80% to less than 5%. The σ_f was nearly 80MPa for 2%Bi and this increases gradually with %Bi concentration peaking at 93MPa for 7%Bi. Results of thermal analysis suggested that solidification went off eutectic after Bi concentration exceeded 2%. Using neutron diffraction techniques, the lattice parameter measurements suggest that the solubility limit of Bi in β Sn (in the multicomponent Sn-Ag-Cu) is about 2wt. %. The existence of Bi rich clusters was responsible for observed brittleness after 2wt.% Bi substitution. With the aid small angle neutron Scattering (SANS) and ultra-small angle neutron scattering (USANS), it was found that the intensity changes with respect to scattering factor (Q) especially for high Q region when the precipitations sizes are below 12.5 nm after concentration exceeded 2%Bi that confirms the existence of primary nanosized Bi precipitates that starts to grow into well-defined Bi phases for higher Bi content.
The effects of Bi substitution for Sn on mechanical properties of Sn-based lead-free solders
(Springer Nature, 2021-08-02) Raza, M; Shewchenko, L; Olofinjana, A; Kent, D; Mata, JP; Haque, R
Pb-free solders are gaining ground as the optimum choice for electrical interconnect materials, however, their higher melting temperature around 217 °C is still an issue that restricts wider adoption. The potential to employ Bi substitution for Sn to lower solder joint processing temperatures has been widely considered. In this work, the mechanical properties of eutectic SAC with gradually increasing Bi substitution up to 10 wt% Bi was studied. It is shown that fracture strength (σf) increases with Bi additions from 50 MPa plateauing at 60 MPa between 1.4 and 1.8% Bi which represents the limits of solid solution strengthening. Over this substitutional range, strain at fracture (εf) dropped from 30 to 10% which was also evidenced by smaller percentage reduction in area (%RA). The σf was nearly 80 MPa for 2% Bi increasing gradually with increasing Bi concentrations and peaking at 93 MPa for 7% Bi whilst maintaining 10% elongation at fracture. X-ray diffraction and DSC thermal studies suggests that the solubility limit of Bi in β-Sn (in the multicomponent SAC) is less than 2 wt% Bi. With the aid of small-angle neutron Scattering (SANS) and ultra-small-angle neutron scattering (USANS), it was found that the scattering intensity changes for alloys with Bi content in the range 0.8 – 1.5wt% compared to ternary SAC with less than 0.8% Bi at low scattering factors (Q > 10 - 2Å - 1) signifying microstructural differences at length scales of the order of 10–100 nm. There were no differences observed in scattering for alloy samples with more than 2 wt% Bi. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
Effects of crowding and environment on the evolution of conformational ensembles of the multi-stimuli-responsive intrinsically disordered protein, Rec1-resilin: a small-angle scattering investigation
(American Chemical Society, 2016-06-09) Balu, R; Mata, JP; Knott, RB; Elvin, CM; Hill, AJ; Choudhury, NR; Dutta, NK
In this study, we explore the overall structural ensembles and transitions of a biomimetic, multi-stimuli-responsive, intrinsically disordered protein (IDP), Rec1-resilin. The structural transition of Rec1-resilin with change in molecular crowding and environment is evaluated using small-angle neutron scattering and small-angle X-ray scattering. The quantitative analyses of the experimental scattering data using a combination of computational models allowed comprehensive description of the structural evolution, organization, and conformational ensembles of Rec1-resilin in response to the changes in concentration, pH, and temperature. Rec1-resilin in uncrowded solutions demonstrates the equilibrium intrinsic structure quality of an IDP with radius of gyration Rg ∼ 5 nm, and a scattering function for the triaxial ellipsoidal model best fit the experimental dataset. On crowding (increase in concentration >10 wt %), Rec1-resilin molecules exert intermolecular repulsive force of interaction, the Rg value reduces with a progressive increase in concentration, and molecular chains transform from a Gaussian coil to a fully swollen coil. It is also revealed that the structural organization of Rec1-resilin dynamically transforms from a rod (pH 2) to coil (pH 4.8) and to globular (pH 12) as a function of pH. The findings further support the temperature-triggered dual-phase-transition behavior of Rec1-resilin, exhibiting rod-shaped structural organization below the upper critical solution temperature (∼4 °C) and a large but compact structure above the lower critical solution temperature (∼75 °C). This work attempted to correlate unusual responsiveness of Rec1-resilin to the evolution of conformational ensembles. © 2016 American Chemical Society
Effects of surfactant transport on high internal phase emulsions under shear: a combined rheological and structural study
(American Institute of Chemical Engineers, 2021-10-19) Yaron, PN; Reynolds, PJ; Mata, JP; White, JW
We report the change in rheological behavior of high-internal phase emulsions (HIPEs) under shear of a polyisobutylene-based (PIBSA) oil-soluble surfactant and with and without the addition of a water-soluble polyacrylamide (PAM) co-surfactant. We used a series of contrast-matched small-angle and ultra-small angle neutron scattering (SANS and USANS) coupled with in situ rheological measurements to track the locations of the surfactant and co-surfactant as a function of shear. This work follows a series of papers analyzing the structural variation and stability of emulsions stabilized with PIBSA and various mixtures of PIBSA/PAM under static and shear conditions. The emulsions’ sensitivity to aqueous/oil phase ratios, surfactant concentration, surfactant molecular weight, and polydispersity has been defined. The emulsions consist of almost spherical micron scale, highly polydisperse, aqueous droplets dispersed in a continuous oil phase with aqueous/oil phase ratios of about 9:1. The emulsions are rheologically unexceptional and follow previously established predictions and theory. The emulsions show refinement to higher viscosity after high shear, and shear thinning. The structural basis for its rheological behavior however does not follow theory. Shear dependent changes observed in the SANS data were tracked by SANS model parameters using a convolution of two well-established models. Shear thinning is explained by SANS observed shear disruption of inter-droplet bilayer links, causing deflocculation to more spherical, less linked, aqueous droplets. Refinement to higher viscosity is accompanied by droplet size reduction and loss of surfactant from the oil continuous phase. Refinement occurs because of shear-induced droplet anisotropy, which we have also observed in the SANS experiment. The observed anisotropy and emulsion refinement cannot be reproduced by either isolated molecule or mean-field models and require a more detailed consideration of interdroplet forces in the sheared fluid. Even at concentrations by the stability limit, a large percentage of surfactant(s) is dissolved as small n-mers or as larger reverse micelles that play an important part in stabilization of the emulsion under shear. Steady shear on PIBSA/PAM emulsions reduces the number of reverse surfactant micelles present in the both the continuous oil phase to provide the surfactant needed to cover the newly formed surface area as the emulsion refines to smaller droplet sizes. Surfactant adsorption to droplet interfaces is accomplished by two processes. The first draws soluble surfactant from the oil phase to the interface and lowers the concentration of dissolved n-meric surfactant. In parallel, oil-soluble reverse micelles begin to break up, allowing a shear rate dependent steady state to establish between the surfactant reservoirs and aqueous droplets. The application of low-shear rate recovery intervals allowed the recovery dynamics of the surfactant distribution to be observed. The results showed little reduction of the emulsion interfacial area upon return to its quiescent state, but a large recovery of the reverse micelle volume fraction that indicates the continuous phase acts as the reservoir of surfactant when the emulsion is under shear. Drastic changes in the rheological behavior of emulsions with PAM co-surfactant indicate different kinetics dictate surfactant and co-surfactant droplet adsorption. We report the effect of altering the chain length and concentration of PAM based co-surfactants (C12-PAM, C14-PAM, and C16-PAM) on the properties of the high-internal phase PIBSA emulsions under shear.
Extended Q-range small angle neutron scattering from inverse micellar solutions of PIBSA—Micelle and molecular scattering
(Elsevier Science BV, 2013-02-15) Mata, JP; Reynolds, PA; Gilbert, EP; White, JW
Inverse micelles play an important role in the stability of high internal phase water in oil (W/O) emulsions. The influence of both solvent and temperature has been investigated on the structure of inverse micelles prepared from the polyisobutylene-based surfactant, PIBSA, using small-angle neutron scattering (SANS). By collecting data over an extended range of scattering vector (Q), combined with the use of solvent deuteration, SANS has highlighted an additional contribution to the anticipated micellar scattering, namely a signal characteristic of rod-like scattering that is consistent with single dissolved molecules of the PIBSA surfactant and its primarily hydrogenated (mainly alkane oil) solvent (both MW ca. 1000 Da). The solvency effect of three different solvents (hexadecane, cyclohexane and toluene) on micellar–monomer (rod) equilibrium has also been evaluated. The volume fractions of rods and micelles in solution are found to agree with the sample compositions, as does the intensity of the observed incoherent background. This consistency across fit parameters not only highlights the sensitivity of the model but also the value of extended Q range, enhanced signal-to-noise studies in such soft matter systems. The data show the extent to which quantitative measurements can be carried at the molecular level using small angle scattering.© 2013, Elsevier Ltd.
Hierarchcial structure of solid lipid nanoparticles
(Australian Institute of Nuclear Science and Engineering (AINSE), 2018-11-19) Shah, R; Mata, JP; Bryan, G; Ife, A; Karpe, A; Jadhav, S; Eldridge, D; Palombo, E; Harding, I; de Campo, L
Suspensions of solid lipid nanoparticles (SLNs) stabilized with emulsifiers have been extensively investigated as drug carriers since the 1990s, although details of their ultrastructure are poorly de fined. Previously, our group reported a novel microwave-assisted microemulsion-based technique Page 22 ANBUG-AINSE Neutron Scattering Symposium, AANSS 2018 / Book of Abstracts to prepare SLNs. Ultrastructure generally relates to interior of the particle and can relate to internal partitioning through, for example, a core-shell structure. It can also relate to the formulation itself, including the particle itself, but can also include structures such as micelles, which may be simultaneously present. Our previous investigations revealed that SLNs were prepared by the novel microemulsion technique have size of 200-300 nm. Preliminary multi-angle SLS/DLS studies indicated core-shell type of SLNs. To understand the detailed ultrastructure of these SLNs, ultra-small angle neutron scattering (USANS) and small angle neutron scattering (SANS) experiments were conducted on suspensions of hydrogenated stearic acid SLNs stabilized with hydrogenated Tween 20 surfactant in D2O. Together, SANS and USANS gave a combined Q range of 4.7 × 10^-5 to 6 × 10^-1 Å^−1 (corresponding to a size range of ~ 1 nm - 15 µm). This extended Q range allows a comprehensive understanding of the hierarchical structure of SLNs. The SANS/USANS data are consistent with the multi-length scale structure of SLNs having polydispersed large particles at the microscale level, intermediate between spheres to rod, with roughened surfaces. At the nanoscale level, the results are consistent with the SLNs solution having an ellipsoidal shape intermediate between spheres and rods, with a crossover from mass fractals to surface fractals. The elucidation of this structure is particularly important given that the structure influences the stability and drug release properties of the nanoparticles. These results will assist in the development of systems with desired shape and properties. © The Authors.
Hierarchical assembly of tryptophan zipper peptides into stress-relaxing bioactive hydrogels
(Springer Nature, 2023-10-23) Nguyen, AK; Molley, TG; Kardia, E; Ganda, S; Chakraborty, S; Wong, SL; Ruan, JF; Yee, BE; Mata, JP; Vijayan, A; Kumar, N; Tilley, RD; Waters, SA; Kilian, KA
Soft materials in nature are formed through reversible supramolecular assembly of biological polymers into dynamic hierarchical networks. Rational design has led to self-assembling peptides with structural similarities to natural materials. However, recreating the dynamic functional properties inherent to natural systems remains challenging. Here we report the discovery of a short peptide based on the tryptophan zipper (trpzip) motif, that shows multiscale hierarchical ordering that leads to emergent dynamic properties. Trpzip hydrogels are antimicrobial and self-healing, with tunable viscoelasticity and unique yield-stress properties that allow immediate harvest of embedded cells through a flick of the wrist. This characteristic makes Trpzip hydrogels amenable to syringe extrusion, which we demonstrate with examples of cell delivery and bioprinting. Trpzip hydrogels display innate bioactivity, allowing propagation of human intestinal organoids with apical-basal polarization. Considering these extensive attributes, we anticipate the Trpzip motif will prove a versatile building block for supramolecular assembly of soft materials for biotechnology and medicine. © 2023 Springer Nature Limited. Open Access. This article is licensed under a Creative Commons Attribution 4.0 International License.

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