Browsing by Author "Kirby, N"

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    The ANSTO contribution to a project to provide experimental standards for SAS profile prediction
    (Australian Institure of Nuclear Sicence and Engineering (AINSE), 2020-11-11) Duff, AP; Kirby, N; Ryan, T; Trewhella, J; Whitten, AE; Wood, K
    The program CRYSOL1, was the first method developed to rapidly calculate small-angle scattering (SAS) profiles from atomic coordinates of biomolecules. It was a major breakthrough, providing the missing link between high-resolution structures and solution SAS data. The importance of this breakthrough is evident in the fact that decades later, alternate methods continue to be published with various claims of improvement. To date, each of the alternate methods published have been validated using different data sets and models. A consensus set of high quality data would be of considerable value in benchmarking the different approaches. In order to evaluate different approaches to including the hydration layer contribution to the SAS profile, it is desirable to have data obtained using X-rays (SAXS) and neutrons (SANS), the latter in H2O and D2O, as the hydration layer contribution differs significantly for each of these measurements. To develop a consensus set of high quality data, an international project involving the efforts of 37 researchers from 11 different X-ray and 3 different neutron scattering facilities across Asia, Europe and North Ⓒ The Authors.
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    Characterisation of embedded nano-precipitates by x-ray diffraction imaging and small-angle x-ray scattering
    (InderScience Publishers, 2014) Pelliccia, D; Andrei, YN; Kirby, N; Hester, JR
    We report on the characterisation of embedded Al2Cu nanoparticles in Al matrix by X-ray diffraction imaging and small-angle X-ray scattering. We employed direct retrieval of the average morphological characteristics of the nanoparticles from their diffraction pattern. Data suggest the possibility of acquiring truly 3D information with X-ray diffraction imaging. Validation of the results obtained with small-angle X-ray scattering is reported. © 2020 Inderscience Enterprises Ltd.
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    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.
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    Conceptual design of the small angle scattering beamline at the Australian Synchrotron
    (American Institute of Physics, 2009-01-19) Kirby, N; Boldeman, JW; Gentle, IR; Cookson, DJ
    A high performance small angle and wide angle x‐ray scattering (SAXS/WAXS) beamline is one of the initial suite of beamlines to be built at the 3 GeV Australian Synchrotron. This beamline will be ready for use in 2008, for structural analysis across a wide range of research applications over length scales of ∼ 1 to greater than 5000 Å. The instrument is intended for advanced analysis capabilities only possible using synchrotron radiation, such as time, space and energy resolved analysis, and for weak scattering systems. Photon energies will be readily variable between 5.2 and 20 keV. © 2007 American Institute of Physics.
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    Controlling the nanostructure of gold nanorod-lyotropic liquid-crystalline hybrid materials using near-infrared laser irradiation
    (American Chemical Society, 2012-10-09) Fong, WK; Hanley, TL; Thierry, B; Kirby, N; Waddington, LJ; Boyd, BJ
    Lipid-based liquid-crystalline matrixes provide a unique prospect for stimuli-responsive nanomaterials, attributed to the ability to effect self-assembly of the lipids at the molecular level. Differences in liquid crystal nanostructure have previously been shown to change drug diffusion and hence release, with research progressing toward the use of in situ changes to nanostructure to control drug release. Toward this goal, we have previously communicated the ability to switch between nonlamellar structures using gold nanorod (GNR)-phytantriol-based liquid-crystalline hybrid nanomaterials as near-infrared light responsive systems (Fong et al. Langmuir 2010, 26, 6136-6139). In this study, the effect of laser activation on matrix nanostructure with changes in a number of system variables including lipid composition, GNR aspect ratio, GNR concentration, and laser pulse time were investigated. The nanostructure of the matrix was followed using small-angle X-ray scattering, while both cryoFESEM and cryoTEM were used to visualize the effect of GNR incorporation into the liquid crystal nanostructure. The system response was found to be dependent on all variables, thus demonstrating the potential of these nanocomposite materials as reversible "on-demand" drug delivery applications. © 2012, American Chemical Society.
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    Guanidine hydrochloride denaturation of dopamine-induced α-synuclein oligomers: a small-angle x-ray scattering study
    (Wiley Online Library, 2013-06-4) Pham, CLL; Kirby, N; Wood, K; Ryan, T; Roberts, B; Sokolova, AV; Barnham, KJ; Masters, CL; Knott, RB; Cappai, R; Curtain, CC; Rekas, A
    Alpha-synuclein (α-syn) forms the amyloid-containing Lewy bodies found in the brain in Parkinson's disease. The neurotransmitter dopamine (DA) reacts with α-syn to form SDS-resistant soluble, non-amyloid, and melanin-containing oligomers. Their toxicity is debated, as is the nature of their structure and their relation to amyloid-forming conformers of α-syn. The small-angle X-ray scattering technique in combination with modeling by the ensemble optimization method showed that the un-reacted native protein populated three broad classes of conformer, while reaction with DA gave a restricted ensemble range suggesting that the rigid melanin molecule played an important part in their structure. We found that 6 M guanidine hydrochloride did not dissociate α-syn DA-reacted dimers and trimers, suggesting covalent linkages. The pathological significance of covalent association is that if they are non-toxic, the oligomers would act as a sink for toxic excess DA and α-syn; if toxic, their stability could enhance their toxicity. We argue it is essential, therefore, to resolve the question of whether they are toxic or not. © 2013,Wiley Periodicals, Inc.
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    In situ SAXS studies of the formation of sodium jarosite
    (Wiley-Blackwell, 2013-07-01) Brand, HEA; Scarlett, NVY; Grey, IE; Knott, RB; Kirby, N
    This paper reports the results of time-resolved synchrotron small-angle scattering and powder diffraction experiments where natrojarosites were synthesized in situ in order to observe the species produced at the earliest stages of nucleation. The sample temperatures were 333, 353 and 368 K. These compounds were synthesized by co-precipitation from solution on the Small and Wide Angle Scattering and Powder Diffraction beamlines at the Australian Synchrotron. Scattering data were collected continuously throughout the syntheses. The results presented here show that the first particles to form in solution appear to be amorphous and nucleate on the walls of the reaction vessel. Crucially, there is a single nucleation event which forms particles with an elliptical disc morphology which then grow uniformly before natrojarosite crystallization is observed in complementary powder diffraction data. This nucleation event may represent the key to controlling the growth of jarosites in industrial and environmental settings. © 2013, Wiley-Blackwell.
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    Liquid crystals with hierarchical ordering
    (International Conference on Neutron Scattering, 2017-07-12) de Campo, L; Moghaddam, M; Sokolova, AV; Rehm, C; Mittelbach, R; Varslot, T; Castle, T; Garvey, CJ; Kirby, N; Hyde, ST
    We present liquid crystal geometries experimentally found for star-polyphilic molecules as the basic building block. Star-polyphiles are small molecules, bearing three mutually immiscible chains attached to a common center [1,2,3]. Like conventional lipids or surfactants (that usually have two immisciblechains), such molecules self-assemble to form lamellar, hexagonal, micellar cubic and bicontinuous cubic structures. However, the presence of the third immiscible chain significantly increases structural complexity and hierarchical ordering can occur.
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    Neutron and synchrotron characterisation techniques for hydrogen fuel cell materials
    (Australian Nuclear Science and Technology Organisation, 2021-11-24) Lamb, K; Kirby, N; Bartlett, JR; Peterson, VK; Appadoo, D; Jiang, SP; De Marco, R
    Hydrogen fuel cells and other renewable energy technologies have specific materials and functional needs which can be more fully understood using neutron and synchrotron characterisation techniques. In this presentation, a materials which has applications in proton exchange membranes is studied with a variety to techniques to develop a comprehensive understanding of the functional-structural relationship. The materials used here is phosphotungstic acid (HPWA) stabilised in an ‘inert’ mesoporous silica host material. This aim of this research is to develop an understanding of the interaction between the HPWA and the silica and whether different structures or surface chemistries have advantageous or detrimental effects. Two silica symmetries used were Ia3 ̅d (face centred cubic bi-continuous) and P6mm (2D hexagonal with cylindrical pores) which were vacuum impregnated with solutions of HPWA in a range of concentrations. The resulting powder samples were then analysed using small angle x-ray scattering (SAXS), inductively coupled plasma emissions spectroscopy (ICP-OES), nitrogen gas adsorption/desorption, near edge X-ray absorption fine structure (NEXAFS/X-ray absorption near edge structure/XANES) of the O and Si k-edges, Fourier transform infra-red spectroscopy (FTIR), Raman spectroscopy, and then formed into a disk using polyethylene as the binder for electrical impedance spectroscopy (EIS). The insights gained from this systematic study indicate that the surface chemistry of the silica host has a significant effect on the performance, uptake and interactions with the HPWA anions, where lower concentrations of HPWA result in stronger host:HPWA interactions but lower conductivity. © The Authors
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    Novel spiropyran amphiphiles and their application as light-responsive liquid crystalline components
    (American Chemical Society, 2013-09-05) Tangso, KJ; Fong, WK; Darwish, TA; Kirby, N; Boyd, BJ; Hanley, TL
    Light-responsive materials formed by liquid crystalline lipids in water have potential application to drug delivery through inclusion of photochromic additives such as spiropyran. A series of novel analogues of spiropyran (SP) have been synthesized with an SP headgroup that possess a C8 (SP-OC), C12 (SP-L), and C16 (SP-P) tail to probe the influence of the length of the hydrophobic tail on their physicochemical properties and effect on behavior in liquid crystal matrices with a view to application as stimulus-responsive elements on ultraviolet irradiation. In addition, compounds possessing an oleyl (SP-OL) and phytanyl (SP-PHYT) tail, to mimic those of the ?parent? reverse bicontinuous cubic (V2) phase forming lipids, glyceryl monooleate (GMO) and phytantriol, were also prepared. The photochromic compounds were characterized by their melting points and photophysical behavior in solution using techniques including hot stage microscopy (HSM), differential scanning calorimetry (DSC), and UV?visible spectroscopy. Their effect on the equilibrium nanostructure of bulk V2 phases and phase-switching kinetics after exposure to UV light was assessed using small-angle X-ray scattering (SAXS). The melting point of the SP derivatives decreased linearly with increasing chain length, which suggests that interactions between the head groups governed their melting point, rather than the van der Waals interactions between the tails. Changing the R group did not influence the equilibrium rate constants for the isomerization of SP. Phase transition temperatures of liquid crystalline (LC) matrices were influenced significantly by incorporation of the SP derivatives and were greatest when the photochromic compound possessed an intermediate tail length substituent compared to the short alkyl or bulkier moieties. The level of disruption of lipid packing, and hence phase structure, were dependent on the duration of UV exposure. © 2013, American Chemical Society.
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    pH-responsive micelles based on caprylic acid
    (ACS Publications, 2014-06-06) Salentinig, S; Phan, S; Darwish, TA; Kirby, N; Boyd, BJ; Gilbert, EP
    Free fatty acids play a vital role as fuel for cells and in lipid metabolism. During lipid digestion in the gastrointestinal tract, triglycerides are hydrolyzed, resulting in free fatty acid and monoglyceride amphiphilic products. These components, together with bile salts, are responsible for the transport of lipids and poorly water-soluble nutrients and xenobiotics from the intestine into the circulatory system of the body. In this study, we show that the self-assembly of digestion products from medium-chain triglycerides (tricaprylin) in combination with bile salt and phospholipid is highly pH-responsive. Individual building blocks of caprylic acid within the mixed colloidal structures are mapped using a combination of small-angle X-ray and neutron scattering combined with both solvent contrast variation and selective deuteration. Modeling of the scattering data shows transitions in the size and shape of the micelles in combination with a transfer of the caprylic acid from the core of the micelles to the shell or into the bulk water upon increasing pH. The results help to understand the process of lipid digestion with a focus on colloidal structure formation and transformation for the delivery of triglyceride lipids and other hydrophobic functional molecules. © 2014, American Chemical Society.
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    Plasmonic nanorods provide reversible control over nanostructure of self-assembled drug delivery materials
    (American Chemical Society, 2010-05-04) Fong, WK; Hanley, TL; Thierry, B; Kirby, N; Boyd, BJ
    The nanostructure of mesophase liquid crystals prepared from amphiphilic lipids controls the rate of release of incorporated agents from the material, such as drug molecules, and reversible transition between different nanostructures essentially provides an “on−off” switch for release (Fong, W.-K.; Hanley, T.; Boyd, B. J. J. Controlled Release 2009, 135, 218−226). In this study, the incorporation of plasmonic hydrophobized gold nanorods (GNRs) permits reversible manipulation of nanostructure on-demand, by irradiation of the matrix using a near-infrared laser. Synchrotron small-angle X-ray scattering was used to probe the kinetics of the response of nanostructure to laser irradiation, and the specificity of the approach is shown by the lack of response in the absence of nanorods, or for GNR whose dimensions are not matched to the specific wavelength of the incident light. © 2010, American Chemical Society
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    Pretreatment control of carbon nanotube array growth for gas separation: alignment and growth studied using microscopy and small-angle x-ray scattering
    (Americal Chemical Society, 2013-04-24) Yang, XS; Yuan, LX; Peterson, VK; Minett, AI; Zhao, MW; Kirby, N; Mudie, ST; Harris, AT
    Aligned multiwalled carbon nanotube (CNT) arrays were prepared using chemical vapor deposition of C2H4 on Fe catalyst at 750 degrees C. CNT array height and alignment depends strongly on the duration of H-2 pretreatment, with optimal height and alignment achieved using 10-15 min pretreatment. Small-angle X-ray scattering (SAXS) was used to quantify the alignment, distribution, and size of the CNTs in arrays produced from varying pretreatment times and the results correlated with microscopy measurements. SAXS analysis revealed that the higher section of the CNT arrays exhibited better alignment than the lower section. Combining these insights with transmission electron microscopy measurements of the CNT defects within each array enable a mechanism for the CNT growth to be proposed, where the loss of alignment arises from deformation of the CNTs during their growth. Gas permeation test across densified CNT arrays indicated that the alignment of the CNT array plays an important role in the gas transport, and that the gas diffusion across the well-aligned CNT arrays was enhanced by a factor of 45, which is much more than that across the poorly aligned CNT arrays, with an enhancement factor of similar to 8. © 2013, American Chemical Society.
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    A round‐robin approach provides a detailed assessment of biomolecular small‐angle scattering data reproducibility and yields consensus curves for benchmarking
    (International Union of Crystallography (IUCr), 2022-11) Trewhella, J; Vachette, P; Bierma, J; Blanchet, Cl; Brookes, E; Chakravarthy, S; Chatzimagas, L; Cleveland, TE; Cowieson, NP; Crossett, B; Duff, AP; Franke, D; Gabel, F; Gillilan, RE; Graewert, MA; Grishaev, A; Guss, JM; Hammel, M; Hopkins, JB; Huang, Q; Hub, JS; Hura, GL; Irving, TC; Jeffries, CM; Jeong, C; Kirby, N; Krueger, S; Martel, A; Matsui, T; Li, N; Pérez, J; Porcar, L; Prangé, T; Rajkovic, I; Rocco, M; Rosenberg, DJ; Ryan, TM; Seifert, S; Sekiguchi, H; Svergun, D; Teixeira, S; Thureau, A; Weiss, TM; Whitten, AE; Wood, K; Zuo, X
    Through an expansive international effort that involved data collection on 12 small-angle X-ray scattering (SAXS) and four small-angle neutron scattering (SANS) instruments, 171 SAXS and 76 SANS measurements for five proteins (ribonuclease A, lysozyme, xylanase, urate oxidase and xylose isomerase) were acquired. From these data, the solvent-subtracted protein scattering profiles were shown to be reproducible, with the caveat that an additive constant adjustment was required to account for small errors in solvent subtraction. Further, the major features of the obtained consensus SAXS data over the q measurement range 0–1 Å−1 are consistent with theoretical prediction. The inherently lower statistical precision for SANS limited the reliably measured q-range to <0.5 Å−1, but within the limits of experimental uncertainties the major features of the consensus SANS data were also consistent with prediction for all five proteins measured in H2O and in D2O. Thus, a foundation set of consensus SAS profiles has been obtained for benchmarking scattering-profile prediction from atomic coordinates. Additionally, two sets of SAXS data measured at different facilities to q > 2.2 Å−1 showed good mutual agreement, affirming that this region has interpretable features for structural modelling. SAS measurements with inline size-exclusion chromatography (SEC) proved to be generally superior for eliminating sample heterogeneity, but with unavoidable sample dilution during column elution, while batch SAS data collected at higher concentrations and for longer times provided superior statistical precision. Careful merging of data measured using inline SEC and batch modes, or low- and high-concentration data from batch measurements, was successful in eliminating small amounts of aggregate or interparticle interference from the scattering while providing improved statistical precision overall for the benchmarking data set. © The Authors published by International Union of Crystallography. Open Access CC-By licence 4.0.
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    Simultaneous reconstruction and structural fitting of the complex atomic fine structure of copper and iron
    (Australian Institute of Physics, 2022-12-11) Di Pasquale, P; Tran, CQ; Chantler, CT; Barnea, Z; Kirk, T; Dao, MN; Balaur, E; van Riessen, GA; Hinsley, GN; Jallandhra, A; Ceddia, J; Rogers, J; Kewish, CM; Paterson, DJ; Reinhardt, J; Kirby, N; Mudie, ST
    A novel technique for determining complex atomic fine structure will be described. Exciting applications of the technique such as a phase analogue to x-ray absorption fine structure applications will also be discussed.
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    Transfer of lipid between triglyceride dispersions and lyotropic liquid crystal nanostructured particles using time-resolved SAXS
    (Royal Society of Chemistry., 2012-04-16) Tilley, AJ; Dong, YD; Chong, JYT; Hanley, TL; Kirby, N; Drummond, CJ; Boyd, BJ
    Lipid-based lyotropic liquid crystalline nanostructured phases, such as the reverse bicontinuous cubic phase (V-2) and the reverse hexagonal phase (H-2), can be dispersed into submicron sized particles with often preserved internal nanostructure, termed cubosomes and hexosomes respectively. The internal nanostructure of the particles imparts desirable characteristics such as the ability to provide sustained release of active ingredients but is susceptible to change upon the incorporation of other lipids used as an active ingredient delivery system. These are complex systems in which the direction of lipid transfer, role of the stabiliser and formation of different phase structures, such as the frustrated H-2 phase are all likely to play a role but are not yet completely understood. Consequently, we have investigated the interparticle transfer of lipids between cubosomes/hexosomes and other dispersed lipids, namely triglycerides and vitamin E acetate emulsions. Time-resolved synchrotron small angle X-ray scattering was used to follow changes to nanostructure, attributed to the transfer of lipids into or out of the cubosomes. It was found that transfer of lipid occurred due to compositional ripening via a micelle-mediated mechanism, evident from the rate of lipid transfer increasing with Pluronic concentration. The rate of transfer of alkanes between liquid crystalline particles and emulsions has been shown previously to depend inversely on chain length. However in the triglyceride systems in the current study, the rate of lipid transfer (trilaurin > tricaprylin > supercooled trimyristin >> crystallised trimyristin and tristearin) did not decrease with increase in the chain length of triglyceride as might be anticipated. The equilibrium phase diagrams of triglyceride + phytantriol in excess water were determined. These diagrams showed that the transfer of phytantriol away from cubosomes to the emulsions, which increases the local triglyceride to phytantriol concentration in the cubosomes, would require formation of H-2 phase more readily for tricaprylin than for trilaurin. Therefore, the lack of correlation of transfer rate with chain length of the triglyceride was attributed to the system seeking to avoid the unfavourable formation of the H-2 phase, competing with the driving force from the entropy of mixing, and was therefore attributed as the reason for the greater rate of transfer of trilaurin compared to the less lipophilic tricaprylin. © 2012 Royal Society of Chemistry