Wednesday 10 July 2013, Strathblane & Cromdale Halls, 16:30-18:30
Poster Session B - Bio-relevant LSS
P.044 Structure changes of casein micelle by microbial transglutaminase studied by SANS
A Len2, L Darnay1 and K Koncz1
1
Corvinus University of Budapest, Hungary, 2Wigner Research Center for Physics, Hungary
The enzyme known as microbial transglutaminase (EC: 2.3.2.12, short term: mTG) is widely used for dairy and meat
products, because it’s protein cross linking action. Casein is one of the main substrate of mTG, that’s why the
enzyme effectively sticks casein micelles together, which leads to even larger casein aggregates, than usual. The
result is a complex casein matrix, which improves the texture of yogurt and probably enhances the product stability
(less whey retention during storage). Although the functions and structure of casein micelles are well-known in the
dairy science the notions are not same and so researchers present different casein micelle models every year. Our
research aim was not only the mapping of the casein micelle structure but also following the effect of the microbial
transglutaminase under dairy fermentation processes.
P.045 Small-angle neutron scattering study of self-assembled sitosterol-oryzanol tubules
E Gilbert1, A Bot2, W Bouwman3, H Sawalha4, R den Adel2, V Garamus5, P Venema4, E van der Linden4 and E Flöter6
1
ANSTO, Australia, 2Unilever Research and Development, The Netherlands, 3Delft University of Technology, The
Netherlands, 4Wageningen University, The Netherlands, 5Helmholtz-Zentrum Geesthacht, Germany, 6Technical
University of Berlin, Germany
The firmness of oil-continuous food products, such as margarine or butter, is based on a network of small
crystallites of triglycerides. Few alternative routes to structure food grade oils are known that are not explained in
essence by fatty acid crystallisation behaviour. One exception is the mixture of gamma-oryzanol with beta-sitosterol,
which forms helical ribbons appearing as tubules through self-assembly. Small-angle neutron scattering was
applied to organogels and emulsion gels based on these plant sterol systems, to investigate the structure of the
sitosterol + oryzanol tubules in more detail. Special attention was given to contrast variation studies by using
various solvents in which the sterol mixture had previously been shown to form tubules. The present study shows
that the wall of the tubule can be considered to consist of two layers, of which the outer layer is composed of the
ferulic acid moieties in the oryzanol. Further refinements in the tubule model are desirable to move the current semiquantitative analysis to a quantitative one.
[1]
Bot et al., Faraday Discussions 158 (2012) 223-238
P.046 Structural modification of starch during enzyme digestion using in-situ small-angle neutron scattering
E Gilbert and J Blazek
ANSTO, Australia
Enzymatic digestion of six starches of different botanical origin was studied in real time by in-situ time-resolved
SANS and complemented by the analysis of native and digested material by X-ray diffraction, differential scanning
calorimetry, SAXS and SEM with the aim of following changes in starch granule nanostructure during enzymatic
digestion. This range of techniques enables coverage over five orders of length-scale as is necessary for this
hierarchically-structured material. Starches studied varied in their digestibility and displayed structural differences
in the course of enzymatic digestion. In the course of digestion, the lamellar peak intensity gradually decreased and
ICNS 2013 International Conference on Neutron Scattering
low-q scattering increased, with trends more substantial for A-type than for B-type starches. These observations
were explained by preferential digestion of the amorphous growth rings. Hydrolysis of the semi-crystalline growth
rings was interpreted on the basis of a liquid-crystalline model for starch considering differences between A-type
and B-type starches in the length and rigidity of amylopectin spacers and branches. As evidenced by differing
morphologies of enzymatic attack among varieties, the existence of granular pores and channels and physical
penetrability of the amorphous growth-ring affect the accessibility of the enzyme to the substrate. The combined
effects of the granule microstructure and the nanostructure of the growth-rings influence the opportunity of the
enzyme to access its substrate; as a consequence, these structures determine the enzymatic digestibility of granular
starches more than the absolute physical densities of the growth-rings.
[1]
Blazek and Gilbert, Carbohydrate Polymers 11 (2010) 3275-3289
P.047 Structural transitions during starch pasting using simultaneous Rapid Visco Analysis and Small-angle
Neutron Scattering
E Gilbert1, J Doutch1, M Bason2, F Franceschini1, K James2 and D Clowes1
1
ANSTO, Australia, 2Perten, Sweden
Rapid Visco Analysis (RVA) is an industry-wide method extensively used for determining the viscous properties of
starch slurries enabling information to be extracted on pasting properties; however little is known about structural
changes that occur during standard protocols. A commercial RVA instrument was modified to enable the passage of
a neutron beam through its heating block and paddle assembly to enable the simultaneous measurement of SANS
and RVA on a variety of commercial starches. SANS measurements were made at 1 minute intervals throughout a
standard 13 minute RVA process across a q range of 0.018 – 0.2 Å-1. In each of the starches, the well-known
lamellar structure was observed up to the point at which the viscosity began to increase markedly. At this stage, the
lamellar structure transformed instantaneously; the scattering patterns are indicative of the formation of a large
scale structure with no apparent semicrystalline properties and whose spatial arrangement may be analysed in
terms of a fractal-like gel. The basic building blocks of this gel, under the assumption that they are spheroidal,
appear to have dimensions of approximately 1 nm across all the starches tested. The sizes of the aggregates formed
are several times larger and were found to vary across the time course of the experiment.
[1]
Doutch et al, Carbohydrate Polymers, 88 (2012) 1061–1071
P.048 Reactions of surfactant protein B monolayers with gas-phase ozone at the air-water interface
J Hemming and K Thompson
Birkbeck College, UK
Lung surfactant is vital for lung function as it reduces the surface tension at the air-water interface to prevent
collapse of the alveoli. Exposure of lung surfactant to the air pollutant ozone is known to cause respiratory distress,
and has been linked to increased risk of death due to respiratory disease. However, little is known about the specific
mechanisms that cause damage to the surfactant. The surfactant is composed mainly of phospholipids, as well as 4
surfactant proteins. The small, hydrophobic surfactant protein B (SP-B) is a fundamental component of the lung
surfactant, as infants born with a deficiency in SP-B do not survive. The proposed function of the protein is to aid respreading of phospholipid monolayers during breathing. Monolayers of SP-B at the air-water interface have been
studied in real-time before, during and after exposure to ozone using a combination of techniques. Surface tension
measurements and fluorescence microscopy of the monolayers showed a very rapid reaction upon exposure to
ozone, leading to a monolayer of altered chemical structure. Neutron reflectivity revealed that the protein remains at
the interface after reaction, although changes in the organisation of the material are evident. Furthermore, neutron
reflectivity of ozone-oxidised SP-B and phospholipid mixtures has indicated that the protein is less able to aid re-
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spreading of the monolayers. It can be concluded that inhalation of ozone from the atmosphere could significantly
impede SP-B function in the lung.
P.049 Using neutron reflection to study the atmospheric oxidation mechanism of an organic monolayer by chlorine
atoms
S Jones1, M King2, A Ward3, A Rennie4, A Hughes5 and R Campbell6
1
Department of Earth Sciences, UK, 2Royal Holloway, University of London, UK, 3Lasers for Science Facility, Science
and Technology Facilities Council, UK, 4Uppsala University Sweden, 5ISIS,UK, 6ILL, France
Aerosols in the atmosphere are known to affect the climate of the Earth directly by scattering and absorbing solar
radiation and also indirectly by acting as cloud condensation nuclei (CCN) which influence cloud formation and
cloud radiative properties.The presence of monolayer organic films on the surface of atmospheric aerosol can affect
CCN formation. Gaseous and liquid phase oxidants are prevalent in the atmosphere and have the potential to
oxidise monolayer films, thus causing a change in aerosol chemical composition and a resultant change in aerosol
cloud formation potential.
The gas phase chlorine atom is important in the marine lower atmosphere. It has recently been shown (Liu et al.,
2011) not to equilibrate with surfaces before reaction unlike gas phase ozone. We have shown that the oxidation of
a monolayer of the lipid DSPC (1,2-distearoyl-sn-glycero-3-phosphocholine) at the air water interface by the gas
phase chlorine atom occurs in a stepwise degradation mechanism (A to B to C to…). DSPC is a realistic proxy of
organic detrital matter found in atmospheric aerosol.
Neutron reflection has been used to investigate the organic film as it is oxidised by gaseous chlorine atoms. Both
the surface coverage and film thickness were found to decrease as the reaction proceeds. However, the oxidation
reaction did not completely remove the film from the interface.
A stepwise degradation mechanism may present opportunities for the organic film to react further with other
atmospheric chemicals. In which case, organic films present on aerosols in the lower marine atmosphere may not
completely inhibit water uptake thus allowing aerosol growth and CCN formation.
P.050 Structures and probable interactions among proteins after heat treatment in presence of ions
S Kundu1, A J Chinchalikar2, K Das1 and V K Aswal2
1
Institute of Advanced Study in Science and Technology, India, 2Bhabha Atomic Research Centre, India
Protein molecules like bovine serum albumin (BSA) show gelation after het treatment and the gelation temperature
depends upon the pH, protein concentration, heating process etc [1]. After gradual heating below gelation
temperature, the protein structure and interactions are observed by varying the Fe+3 ion concentrations. It is
observed from the SANS analysis that fractal structure [2,3] is observed at a particular ion concentration which is
the probable condition of gel formation. Below and above that ion concentration the gelation is less favorable.
Nearly the same type of structure and interactions are observed from the proteins in presence of ions with and
without heat treatment.
[1]
[2]
[3]
W. S. Gosal, and S. B. Ross-Murphy,Curr. Opin. Colloid Interface Sci. 2000, 5, 188
P. Aymard, T. Nicolai, and D. Durand, Macromolecules 1999, 32, 2542
S. Chodankar, V. K. Aswal, J. Kohlbrecher, R. Vavrin, and A. G. Wagh, Phys. Rev.E 2009, 79, 021912
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P.051 Dental restorative materials: Hydration process and porosity seen by X-rays and neutron imaging
B Lehnhoff1, H Bordallo1, M Strobl2, A R Benetti1, N Kardjilov3 and A Hilger3
1
Copenhagen University, Denmark, 2European Spallation Source ESS AB, Sweden, 3Helmholtz-Zentrum Berlin,
Germany
Amongst the dental restorative materials, glass ionomer cements are suitable in caries-preventive therapies due to
their release of fluoride and consequent antimicrobial activity. The acid-base reaction rapidly results in the
hardening of the material, but the setting reaction carries on mainly during the first 24 hours and slowly continuing
for up to several months. In order to improve the analysis between different dental cements, and considering the
development of new materials to be used in dental treatments, insights on parameters such as the hydration
process and pore structure of the glass ionomer cements are very important.
In the present study, X-rays and neutron imaging were combined in order to investigate the hydration process and
pore size distribution of the glass ionomer cements in-situ. The two investigated cements consisted of powder-liquid
mixtures, being the powder a calcium aluminum silicate glass and the liquid pure water (Aqua) or a polyacrylic acid
solution (Poly). The experiments confirmed shrinkage of the overall structure during setting, which occurred earlier
and nearly-stabilized for the Poly cement. In a moist environment, the cements absorbed water, compensating for
the setting shrinkage. The pore structure of the dental cements is complex and the pore sizes are highly variable. A
power-law distribution of the pore sizes spanning over two decades was found, which, dependent on the
experimental conditions, gave rise to different slopes. X-rays and neutrons complimented each other nicely as
imaging techniques by having different contrast for the different investigated materials, and may be beneficial in
future research on dental cements.
P.052 Preparation and structural characterization of functionalized theranostic nanoparticles
A Luchini1, G Mangiapia1, G Vitiello1, G D'Errico1, A Radulescu2, M-S Appavou2, D Montesarchio1 and L Paduano1
1
University of Naples, Italy, 2Juelich Centre for Neutron Science, Germany
We present the preparation and structural properties characterization of novel functionalized iron oxide – gold
(Fe3O4@Au) nanoparticles with core-shell structure, as theranostic agents.
The remarkable magnetic properties of Fe3O4-based nanoparticles and their proved biocompatibily, made them
valid contrast agent for magnetic resonance imaging technique, and, because of the presence of the gold shell, also
efficient nanocarriers for drug delivery. The novelty of this work is represented by the functionalization of Fe 3O4@Au
nanoparticles with two layers of amphiphilic molecules, including different amphiphilic ruthenium complexes,
showing high antiproliferative activity. Since nanoparticle functionalization is based on hydrophobic interaction, the
antitumoral agent is reversibly bound on nanoparticle surface and thus it can be easily released in cancer cells to
explicate its activity.
The characterization of the structural properties of functionalized Fe3O4@Au nanoparticles included mostly small
angle neutron scattering, dynamic light scattering, electron paramagnetic resonance, and electron cryomicroscopy
measurements. In particular, the collected SANS data have revealed fundamental in order to define nanoparticle
core-shell structure and shape.
The developed functionalized Fe3O4@Au nanoparticles have already undergo previous in vitrobioscreenings over a
panel of cultured tumor and non-tumor cell lines, showing promising results for their application as theranostic
agents.
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P.053 Nano-porous structures of a compacted ceramic by small angle neutron scattering
R Raut Dessai1, E Desa1, D Sen2 and S Mazumder2
1
Goa University, India, 2Bhabha Atomic Research Centre, India
Porous ceramics have wide applications such as in: filtration of fluids ; removal of dust particles and bacteria ;
separation of large molecules in a liquid stream ; and high sensitivity biosensors. A ceramic powder obtained from
rice husksilica was compacted and sintered to yield a complex porous structure. Transport properties of a
compacted ceramic depend on pore sizes and their interconnections. The porosity of compacts is found to decrease
from 47 to 32% as the compaction pressure is increased. Porosity decreases with both compaction pressure and
sintering temperature though at different rates. Bulk densities and scanning electron micrographs show
densification of the porous ceramic with pressure and temperature together with increase in particle size. Small
Angle Neutron Scattering on the dry and D2O loaded compacts showed mesoscopic porous structures with two
distinct zones in the scattering profiles indicating the presence of pores with two widely different length scales viz.
162 and 32 nm. Pore sizes decreased with compaction pressure. The connectivity of pores at this nanometric length
scale was also established.The fractal dimension lies between 2.8 to 2.97.
[1]
D. Sen, A.K. Patra, S. Mazumder, S. Ramanathan, Journal of Alloys and Compounds 340, 236- 241(2002)
P.054 High time resolution neutron reflectometry for understanding atmospheric chemical reactions
F Sebastiani1,2, R A Campbell1and C Pfrang2
1
Institut Laue Langevin, France, 2University of Reading, UK
The understanding of the ageing of organic films on atmospheric aerosols is still incomplete leading to uncertainties
in models of global warming. We present a surface study of the oxidation kinetics of pure and mixed films of oleic
acid (OA) and stearic acid (SA) by nitrogen oxides. While bulk studies suggest that OA is more reactive than SA due
to the presence of unsaturation, its surface reaction scheme and related kinetic parameters to feed into
atmospheric models are missing. Films at the air-water interface of a Langmuir trough were exposed to the oxidant
and the loss material at the surface during the reaction is followed by neutron reflectometry. The FIGARO instrument
optimized for low-Q data acquisition results in a time resolution as fast as 1 s.
The lifetime of the OA surface layer was shown to be at least two orders of magnitude shorter than that of the SA
surface layer. The rate coefficients are used to refine the surface reaction schemes involved. Also, even at long
timescales ~10% coverage of OA remained. Oxidation of recompressed films is discussed to determine the nature
of the residual material (products vs reoriented reactant). Lastly, the oxidation by nitrous oxides of mixed OA/SA
films has been studied for the first time to measure the relative reaction rates of components in more realistic
models for atmospheric surfactants. The data are rationalised in relation to isotherms and complementary
measurements using ellipsometry and Brewster angle microscopy.
P.055 Structures of protein nanotube complex with cationic polymer
C Song1, Y Kim1, H Miller2, L Wilson2, C R Safinya2, M W Kim1 and M C Choi1
1
Korea Advanced Institute of Science and Technology, Korea, 2UCSB, USA
Microtubules (MTs) are hollow, cylindrical protein nanotubes with inner and outer diameters of ~15 and 25 nm,
respectively, involved in a variety of cellular functions, including cell division, intracellular trafficking, and cell
morphology. We show our recent findings on hierarchical assembly structures of MTs with cationic polymer from
nanoscale to mesoscopic scale by using transmission electron micrography (TEM) and small angle neutron/x-ray
scattering techniques. Supported by NRF 2011-0031931, 2011-0030923, 2012-R1A1A1011023, 2011-355C00037, KAIST N10110077, and G04100061.
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P.056 Lyophilised protein dynamics: More than just methyls?
M Telling1, V Garcia Sakai1, L Clifton1, S Howells1, B Frick2 and J Combet2
1
STFC, UK, 2ILL, France
Neutron spectroscopy has been used to probe picosecond to nanosecond dynamics in lyophilised apoferritin,
insulin, superoxide dismutase and green fluorescent protein. These proteins have markedly different secondary
structures yet similar CH3 compositions. Results suggest that while only CH3 activation is apparent in apoferritin, an
enhanced dynamic environment presents itself in Ins, SOD and GfP. Our results hint at a structure dependent
dynamic landscape.
P.057 Neutron reflectometry study of the interactions of PAMAM dendrimers with amphiphiles at liquid interfaces
M Yanez Arteta1, C Eriksson1, F Eltes1, D Berti2, P Baglioni2, R Campbell3 and T Nylander1
1
Lund University, Sweden, 2University of Florence, Italy, 3Institut Laue-Langevin, France
We have employed neutron reflectometry (NR) in combination with other techniques to reveal the interactions of
cationic poly(amidoamine) (PAMAM) dendrimers with the anionic surfactants sodium dodecyl sulfate (SDS) and
dilauroylphospholiponucleosides (DLPN) at the silica/water and air/water interface. PAMAM dendrimers are welldefined polymers with a hierarchical architecture which make them promising materials as nanocapsules and gene
vectors. DLPNs are based on adenosine or uridine with capacity for molecular recognition of DNA and RNA. At the
air/water interface, there is a synergistic enhancement of adsorbed surfactant in the presence of PAMAM
dendrimers. NR profiles of PAMAM generation 2 with SDS show a Bragg peak depending on the isotopic
composition indicating interfacial multilayers, while generation 4 and 8 do not show this behavior. At the
solid/liquid interface, PAMAM generation 4 and 8 adsorb irreversibly on silica and both SDS and DLPNs interact
with the pre adsorbed layer of dendrimers. Exposure to low SDS concentrations results in swelling of the adsorbed
layer, while the data recorded at high concentrations reveal surfactant aggregation around the polymer layer. For the
DLPNs the interfacial layers are independent of their concentration. The improved understanding of
PAMAM/surfactant interactions at interfaces outlined in this work broadens the fundamental knowledge towards
future dendrimer applications interacting with amphiphiles.
ICNS 2013 International Conference on Neutron Scattering